WorldWideScience

Sample records for activity exacerbates insulin

  1. Myeloid Cell-specific Disruption of Period1 and Period2 Exacerbates Diet-induced Inflammation and Insulin Resistance*

    Science.gov (United States)

    Xu, Hang; Li, Honggui; Woo, Shih-Lung; Kim, Sam-Moon; Shende, Vikram R.; Neuendorff, Nichole; Guo, Xin; Guo, Ting; Qi, Ting; Pei, Ya; Zhao, Yan; Hu, Xiang; Zhao, Jiajia; Chen, Lili; Chen, Lulu; Ji, Jun-Yuan; Alaniz, Robert C.; Earnest, David J.; Wu, Chaodong

    2014-01-01

    The circadian clockworks gate macrophage inflammatory responses. Given the association between clock dysregulation and metabolic disorders, we conducted experiments to determine the extent to which over-nutrition modulates macrophage clock function and whether macrophage circadian dysregulation is a key factor linking over-nutrition to macrophage proinflammatory activation, adipose tissue inflammation, and systemic insulin resistance. Our results demonstrate that 1) macrophages from high fat diet-fed mice are marked by dysregulation of the molecular clockworks in conjunction with increased proinflammatory activation, 2) global disruption of the clock genes Period1 (Per1) and Per2 recapitulates this amplified macrophage proinflammatory activation, 3) adoptive transfer of Per1/2-disrupted bone marrow cells into wild-type mice potentiates high fat diet-induced adipose and liver tissue inflammation and systemic insulin resistance, and 4) Per1/2-disrupted macrophages similarly exacerbate inflammatory responses and decrease insulin sensitivity in co-cultured adipocytes in vitro. Furthermore, PPARγ levels are decreased in Per1/2-disrupted macrophages and PPARγ2 overexpression ameliorates Per1/2 disruption-associated macrophage proinflammatory activation, suggesting that this transcription factor may link the molecular clockworks to signaling pathways regulating macrophage polarization. Thus, macrophage circadian clock dysregulation is a key process in the physiological cascade by which diet-induced obesity triggers macrophage proinflammatory activation, adipose tissue inflammation, and insulin resistance. PMID:24770415

  2. Myeloid cell-specific disruption of Period1 and Period2 exacerbates diet-induced inflammation and insulin resistance.

    Science.gov (United States)

    Xu, Hang; Li, Honggui; Woo, Shih-Lung; Kim, Sam-Moon; Shende, Vikram R; Neuendorff, Nichole; Guo, Xin; Guo, Ting; Qi, Ting; Pei, Ya; Zhao, Yan; Hu, Xiang; Zhao, Jiajia; Chen, Lili; Chen, Lulu; Ji, Jun-Yuan; Alaniz, Robert C; Earnest, David J; Wu, Chaodong

    2014-06-06

    The circadian clockworks gate macrophage inflammatory responses. Given the association between clock dysregulation and metabolic disorders, we conducted experiments to determine the extent to which over-nutrition modulates macrophage clock function and whether macrophage circadian dysregulation is a key factor linking over-nutrition to macrophage proinflammatory activation, adipose tissue inflammation, and systemic insulin resistance. Our results demonstrate that 1) macrophages from high fat diet-fed mice are marked by dysregulation of the molecular clockworks in conjunction with increased proinflammatory activation, 2) global disruption of the clock genes Period1 (Per1) and Per2 recapitulates this amplified macrophage proinflammatory activation, 3) adoptive transfer of Per1/2-disrupted bone marrow cells into wild-type mice potentiates high fat diet-induced adipose and liver tissue inflammation and systemic insulin resistance, and 4) Per1/2-disrupted macrophages similarly exacerbate inflammatory responses and decrease insulin sensitivity in co-cultured adipocytes in vitro. Furthermore, PPARγ levels are decreased in Per1/2-disrupted macrophages and PPARγ2 overexpression ameliorates Per1/2 disruption-associated macrophage proinflammatory activation, suggesting that this transcription factor may link the molecular clockworks to signaling pathways regulating macrophage polarization. Thus, macrophage circadian clock dysregulation is a key process in the physiological cascade by which diet-induced obesity triggers macrophage proinflammatory activation, adipose tissue inflammation, and insulin resistance.

  3. Endothelin-1 exacerbates development of hypertension and atherosclerosis in modest insulin resistant syndrome.

    Science.gov (United States)

    Lin, Yan-Jie; Juan, Chi-Chang; Kwok, Ching-Fai; Hsu, Yung-Pei; Shih, Kuang-Chung; Chen, Chin-Chang; Ho, Low-Tone

    2015-05-08

    activation, whereas remained insulin-induced ERK activation. ET-1 and insulin synergistically potentiated migration and proliferation mainly through ETAR/ERK dependent pathway, which is dominant in VSMCs during modest insulin resistance syndrome. Therefore, ET-1 and ETAR are potential targets responsible for the observed synergism effect in the hypertensive atherosclerotic process through enhancement of ET-1 binding, ET-1 binding, ETAR expression, and ET-1-induced mitogenic actions in aortic VSMCs.

  4. Suppression of Ghrelin Exacerbates HFCS-Induced Adiposity and Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Xiaojun Ma

    2017-06-01

    Full Text Available High fructose corn syrup (HFCS is widely used as sweetener in processed foods and soft drinks in the United States, largely substituting sucrose (SUC. The orexigenic hormone ghrelin promotes obesity and insulin resistance; ghrelin responds differently to HFCS and SUC ingestion. Here we investigated the roles of ghrelin in HFCS- and SUC-induced adiposity and insulin resistance. To mimic soft drinks, 10-week-old male wild-type (WT and ghrelin knockout (Ghrelin−/− mice were subjected to ad lib. regular chow diet supplemented with either water (RD, 8% HFCS (HFCS, or 10% sucrose (SUC. We found that SUC-feeding induced more robust increases in body weight and body fat than HFCS-feeding. Comparing to SUC-fed mice, HFCS-fed mice showed lower body weight but higher circulating glucose and insulin levels. Interestingly, we also found that ghrelin deletion exacerbates HFCS-induced adiposity and inflammation in adipose tissues, as well as whole-body insulin resistance. Our findings suggest that HFCS and SUC have differential effects on lipid metabolism: while sucrose promotes obesogenesis, HFCS primarily enhances inflammation and insulin resistance, and ghrelin confers protective effects for these metabolic dysfunctions.

  5. Endothelin-1 exacerbates development of hypertension and atherosclerosis in modest insulin resistant syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yan-Jie [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China); Juan, Chi-Chang [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Kwok, Ching-Fai [Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Hsu, Yung-Pei [Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China); Shih, Kuang-Chung [Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Chen, Chin-Chang [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Ho, Low-Tone, E-mail: ltho@vghtpe.gov.tw [Institute of Physiology, National Yang-Ming University, Taipei, Taiwan (China); Division of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (China); Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan (China); Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan (China)

    2015-05-08

    suppressed insulin-induced AKT activation, whereas remained insulin-induced ERK activation. ET-1 and insulin synergistically potentiated migration and proliferation mainly through ET{sub A}R/ERK dependent pathway, which is dominant in VSMCs during modest insulin resistance syndrome. Therefore, ET-1 and ET{sub A}R are potential targets responsible for the observed synergism effect in the hypertensive atherosclerotic process through enhancement of ET-1 binding, ET-1 binding, ET{sub A}R expression, and ET-1-induced mitogenic actions in aortic VSMCs. - Highlights: • ET-1/ET{sub A}R signaling and insulin-induced pERK were high in modest insulin resistance. • ET-1 via ET{sub A}R suppressed insulin-induced pAKT but remained intact pERK in VSMCs. • Insulin potentiated ET-1-induced VSMC mitogenic action was ET{sub A}R/ERK dependent.

  6. High Protein Intake Improves Insulin Sensitivity but Exacerbates Bone Resorption in Immobility (WISE Study)

    Science.gov (United States)

    Heer, Martina; Smith, Scott M.; Frings-Meuthen, Petra; Zwart, Sara R.; Baecker, Natalie

    2012-01-01

    Inactivity, like bed rest (BR), causes insulin resistance (IR) and bone loss even in healthy subjects. High protein intake seems to mitigate this IR but might exacerbate bone loss. We hypothesized that high protein intake (animal:vegetable protein ratio: 60:40), isocaloric, compared to the control group plus high potassium intake would prevent IR without affecting bone turnover. After a 20-day ambulatory adaptation to controlled confinement and diet, 16 women participated in a 60-day, 6 deg head-down-tilt BR and were assigned randomly to one of the two groups. Control subjects (CON, n=8) received 1g/kg body mass/d dietary protein. Nutrition subjects (NUT, n=8) received 1.45g/kg body mass/d dietary protein plus 7.2g branched chain amino acids per day during BR. All subjects received 1670 kcal/d. Bed rest decreased glucose disposal by 35% (pprotein intake prevented insulin resistance, but exacerbated bed rest induced increase in bone resorption markers C-telopeptide (> 30%) and Ntelopeptide (>20%) (both: pprotein intake. We conclude from these results that high protein intake might positively affect glucose tolerance, but might also foster bone loss. Further long-duration studies are mandatory before high protein intake for diabetic patients, who have an increased fracture risk, might be recommended.

  7. Insulin deficiency exacerbates cerebral amyloidosis and behavioral deficits in an Alzheimer transgenic mouse model

    Directory of Open Access Journals (Sweden)

    Teng Wei-Ping

    2010-11-01

    Full Text Available Abstract Background Although increasing evidence has indicated that brain insulin dysfunction is a risk factor for Alzheimer disease (AD, the underlying mechanisms by which insulin deficiency may impact the development of AD are still obscure. Using a streptozotocin (STZ-induced insulin deficient diabetic AD transgenic mouse model, we evaluated the effect of insulin deficiency on AD-like behavior and neuropathology. Results Our data showed that administration of STZ increased the level of blood glucose and reduced the level of serum insulin, and further decreased the phosphorylation levels of insulin receptors, and increased the activities of glycogen synthase kinase-3α/β and c-Jun N-terminal kinase in the APP/PS1 mouse brain. We further showed that STZ treatment promoted the processing of amyloid-β (Aβ precursor protein resulting in increased Aβ generation, neuritic plaque formation, and spatial memory deficits in transgenic mice. Conclusions Our present data indicate that there is a close link between insulin deficient diabetes and cerebral amyloidosis in the pathogenesis of AD.

  8. Macrophage activation in acute exacerbation of idiopathic pulmonary fibrosis.

    Directory of Open Access Journals (Sweden)

    Jonas Christian Schupp

    Full Text Available Acute exacerbation (AE of idiopathic pulmonary fibrosis (IPF is a common cause of disease acceleration in IPF and has a major impact on mortality. The role of macrophage activation in AE of IPF has never been addressed before.We evaluated BAL cell cytokine profiles and BAL differential cell counts in 71 IPF patients w/wo AE and in 20 healthy volunteers. Twelve patients suffered from AE at initial diagnosis while sixteen patients developed AE in the 24 months of follow-up. The levels of IL-1ra, CCL2, CCL17, CCL18, CCL22, TNF-α, IL-1β, CXCL1 and IL-8 spontaneously produced by BAL-cells were analysed by ELISA.In patients with AE, the percentage of BAL neutrophils was significantly increased compared to stable patients. We found an increase in the production rate of the pro-inflammatory cytokines CXCL1 and IL-8 combined with an increase in all tested M2 cytokines by BAL-cells. An increase in CCL18 levels and neutrophil counts during AE was observed in BAL cells from patients from whom serial lavages were obtained. Furthermore, high baseline levels of CCL18 production by BAL cells were significantly predictive for the development of future AE.BAL cell cytokine production levels at acute exacerbation show up-regulation of pro-inflammatory as well as anti-inflammatory/ M2 cytokines. Our data suggest that AE in IPF is not an incidental event but rather driven by cellular mechanisms including M2 macrophage activation.

  9. Daily activity during stability and exacerbation of chronic obstructive pulmonary disease.

    Science.gov (United States)

    Alahmari, Ayedh D; Patel, Anant R C; Kowlessar, Beverly S; Mackay, Alex J; Singh, Richa; Wedzicha, Jadwiga A; Donaldson, Gavin C

    2014-06-02

    During most COPD exacerbations, patients continue to live in the community but there is little information on changes in activity during exacerbations due to the difficulties of obtaining recent, prospective baseline data. Patients recorded on daily diary cards any worsening in respiratory symptoms, peak expiratory flow (PEF) and the number of steps taken per day measured with a Yamax Digi-walker pedometer. Exacerbations were defined by increased respiratory symptoms and the number of exacerbations experienced in the 12 months preceding the recording of daily step count used to divide patients into frequent (> = 2/year) or infrequent exacerbators. The 73 COPD patients (88% male) had a mean (±SD) age 71(±8) years and FEV1 53(±16)% predicted. They recorded pedometer data on a median 198 days (IQR 134-353). At exacerbation onset, symptom count rose by 1.9(±1.3) and PEF fell by 7(±13) l/min. Mean daily step count fell from 4154(±2586) steps/day during a preceding baseline week to 3673(±2258) step/day during the initial 7 days of exacerbation (p = 0.045). Patients with larger falls in activity at exacerbation took longer to recover to stable level (rho = -0.56; p < 0.001). Recovery in daily step count was faster (median 3.5 days) than for exacerbation symptoms (median 11 days; p < 0.001). Recovery in step count was also faster in untreated compared to treated exacerbation (p = 0.030).Daily step count fell faster over time in the 40 frequent exacerbators, by 708 steps/year, compared to 338 steps/year in 33 infrequent exacerbators (p = 0.002). COPD exacerbations reduced physical activity and frequent exacerbations accelerate decline in activity over time.

  10. Diclofenac derivatives with insulin-sensitizing activity

    Institute of Scientific and Technical Information of China (English)

    Jian Ta Wang; Ying Wang; Ji Quan Zhang; Xing Cui; Yi Zhang; Gao Feng Zhu; Lei Tang

    2011-01-01

    A series of diclofenac derivatives were synthesized. The insulin-sensitizing activity of 28 new compounds was evaluated in 3T3-L1 cells. The compounds 10a and 10f exhibited similar insulin-sensitizing activity with positive drag rosiglitazone.

  11. Activity-Related Symptom Exacerbations After Pediatric Concussion.

    Science.gov (United States)

    Silverberg, Noah D; Iverson, Grant L; McCrea, Michael; Apps, Jennifer N; Hammeke, Thomas A; Thomas, Danny G

    2016-10-01

    Recovery from concussion generally follows a trajectory of gradual improvement, but symptoms can abruptly worsen with exertion. This phenomenon is poorly understood. To characterize the incidence, course, and clinical significance of symptom exacerbations (spikes) in children after concussion. This secondary analysis of clinical trial data analyzes 63 eligible participants prospectively recruited from an emergency department who were asked to complete a postconcussion symptom scale and record their activities in a structured diary for the next 10 days. They completed standardized assessments of symptoms (postconcussion symptom scale), cognition (Immediate Post-Concussion Assessment and Cognitive Testing), and balance (Balance Error Scoring System) 10 days following the injury. Eligible participants were aged 11 to 18 years and sustained a concussion (according to the Centers for Disease Control and Prevention criteria) that did not result in an abnormal computed tomography scan or require hospital admission. The trial was conducted from May 2010 to December 2012, and the analysis was conducted from November 2015 to February 2016. The occurrence of symptom spikes, defined as an increase of 10 or more points on the postconcussion symptom scale over consecutive days. Of the 63 participants, there were 41 boys (65.1%) and 22 girls (34.9%), and the mean (SD) age was 13.8 (1.8) years. Symptom spikes occurred in one-third of the sample (20 participants [31.7%]). Symptom spikes tended to partially resolve within 24 hours. An abrupt increase in mental activity (ie, returning to school and extracurricular activities) from one day to the next increased the risk of a symptom spike (relative risk, 0.81; 95% CI, 0.21-3.21), but most symptom spikes were not preceded by a documented increase in physical or mental activity. Patients with symptom spikes were initially more symptomatic in the emergency department and throughout the observation period but did not differ from the group

  12. Lack of Adipocyte AMPK Exacerbates Insulin Resistance and Hepatic Steatosis through Brown and Beige Adipose Tissue Function

    DEFF Research Database (Denmark)

    Mottillo, Emilio P; Desjardins, Eric M; Crane, Justin D

    2016-01-01

    Brown (BAT) and white (WAT) adipose tissues play distinct roles in maintaining whole-body energy homeostasis, and their dysfunction can contribute to non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes. The AMP-activated protein kinase (AMPK) is a cellular energy sensor, but its role...... in mitochondrial structure, function, and markers of mitophagy. In response to a high-fat diet, iβ1β2AKO mice more rapidly developed liver steatosis as well as glucose and insulin intolerance. Thus, AMPK in adipocytes is vital for maintaining mitochondrial integrity, responding to pharmacological agents...... and thermal stress, and protecting against nutrient-overload-induced NAFLD and insulin resistance....

  13. Intermittent fasting reduces body fat but exacerbates hepatic insulin resistance in young rats regardless of high protein and fat diets.

    Science.gov (United States)

    Park, Sunmin; Yoo, Kyung Min; Hyun, Joo Suk; Kang, Suna

    2017-02-01

    Intermittent fasting (IMF) is a relatively new dietary approach to weight management, although the efficacy and adverse effects have not been full elucidated and the optimal diets for IMF are unknown. We tested the hypothesis that a one-meal-per-day intermittent fasting with high fat (HF) or protein (HP) diets can modify energy, lipid, and glucose metabolism in normal young male Sprague-Dawley rats with diet-induced obesity or overweight. Male rats aged 5 weeks received either HF (40% fat) or HP (26% protein) diets ad libitum (AL) or for 3 h at the beginning of the dark cycle (IMF) for 5 weeks. Epidydimal fat pads and fat deposits in the leg and abdomen were lower with HP and IMF. Energy expenditure at the beginning of the dark cycle, especially from fat oxidation, was higher with IMF than AL, possibly due to greater activity levels. Brown fat content was higher with IMF. Serum ghrelin levels were higher in HP-IMF than other groups, and accordingly, cumulative food intake was also higher in HP-IMF than HF-IMF. HF-IMF exhibited higher area under the curve (AUC) of serum glucose at the first part (0-40 min) during oral glucose tolerance test, whereas AUC of serum insulin levels in both parts were higher in IMF and HF. During intraperitoneal insulin tolerance test, serum glucose levels were higher with IMF than AL. Consistently, hepatic insulin signaling (GLUT2, pAkt) was attenuated and PEPCK expression was higher with IMF and HF than other groups, and HOMA-IR revealed significantly impaired attenuated insulin sensitivity in the IMF groups. However, surprisingly, hepatic and skeletal muscle glycogen storage was higher in IMF groups than AL. The higher glycogen storage in the IMF groups was associated with the lower expression of glycogen phosphorylase than the AL groups. In conclusion, IMF especially with HF increased insulin resistance, possibly by attenuating hepatic insulin signaling, and lowered glycogen phosphorylase expression despite decreased fat mass in young

  14. Combination of alcohol and fructose exacerbates metabolic imbalance in terms of hepatic damage, dyslipidemia, and insulin resistance in rats.

    Science.gov (United States)

    Alwahsh, Salamah Mohammad; Xu, Min; Schultze, Frank Christian; Wilting, Jörg; Mihm, Sabine; Raddatz, Dirk; Ramadori, Giuliano

    2014-01-01

    Although both alcohol and fructose are particularly steatogenic, their long-term effect in the development of a metabolic syndrome has not been studied in vivo. Consumption of fructose generally leads to obesity, whereas ethanol can induce liver damage in the absence of overweight. Here, Sprague-Dawley rats were fed ad libitum for 28 days on five diets: chow (control), liquid Lieber-DeCarli (LDC) diet, LDC +30%J of ethanol (L-Et) or fructose (L-Fr), and LDC combined with 30%J ethanol and 30%J fructose (L-EF). Body weight (BW) and liver weight (LW) were measured. Blood and liver samples were harvested and subjected to biochemical tests, histopathological examinations, and RT-PCR. Alcohol-containing diets substantially reduced the food intake and BW (≤3rd week), whereas fructose-fed animals had higher LW than controls (Pfructose-administered rats. Compared to the chow and LDC diets, the L-EF diet significantly elevated blood glucose, insulin, and total-cholesterol levels (also vs. the L-Et group). The albumin and Quick-test levels were the lowest, whereas ALT activity was the highest in the L-EF group. Moreover, the L-EF diet aggravated plasma triglyceride and reduced HDL-cholesterol levels more than 2.7-fold compared to the sum of the effects of the L-Et and L-Fr diets. The decreased hepatic insulin clearance in the L-EF group vs. control and LDC groups was reflected by a significantly decreased C-peptide:insulin ratio. All diets except the control caused hepatosteatosis, as evidenced by Nile red and H&E staining. Hepatic transcription of insulin receptor substrate-1/2 was mainly suppressed by the L-Fr and L-EF diets. The L-EF diet did not enhance the mitochondrial β-oxidation of fatty acids (Cpt1α and Ppar-α expressions) compared to the L-Et or L-Fr diet. Together, our data provide evidence for the coaction of ethanol and fructose with a high-fat-diet on dyslipidemia and insulin resistance-accompanied liver damage.

  15. Combination of alcohol and fructose exacerbates metabolic imbalance in terms of hepatic damage, dyslipidemia, and insulin resistance in rats.

    Directory of Open Access Journals (Sweden)

    Salamah Mohammad Alwahsh

    Full Text Available Although both alcohol and fructose are particularly steatogenic, their long-term effect in the development of a metabolic syndrome has not been studied in vivo. Consumption of fructose generally leads to obesity, whereas ethanol can induce liver damage in the absence of overweight. Here, Sprague-Dawley rats were fed ad libitum for 28 days on five diets: chow (control, liquid Lieber-DeCarli (LDC diet, LDC +30%J of ethanol (L-Et or fructose (L-Fr, and LDC combined with 30%J ethanol and 30%J fructose (L-EF. Body weight (BW and liver weight (LW were measured. Blood and liver samples were harvested and subjected to biochemical tests, histopathological examinations, and RT-PCR. Alcohol-containing diets substantially reduced the food intake and BW (≤3rd week, whereas fructose-fed animals had higher LW than controls (P<0.05. Additionally, leukocytes, plasma AST and leptin levels were the highest in the fructose-administered rats. Compared to the chow and LDC diets, the L-EF diet significantly elevated blood glucose, insulin, and total-cholesterol levels (also vs. the L-Et group. The albumin and Quick-test levels were the lowest, whereas ALT activity was the highest in the L-EF group. Moreover, the L-EF diet aggravated plasma triglyceride and reduced HDL-cholesterol levels more than 2.7-fold compared to the sum of the effects of the L-Et and L-Fr diets. The decreased hepatic insulin clearance in the L-EF group vs. control and LDC groups was reflected by a significantly decreased C-peptide:insulin ratio. All diets except the control caused hepatosteatosis, as evidenced by Nile red and H&E staining. Hepatic transcription of insulin receptor substrate-1/2 was mainly suppressed by the L-Fr and L-EF diets. The L-EF diet did not enhance the mitochondrial β-oxidation of fatty acids (Cpt1α and Ppar-α expressions compared to the L-Et or L-Fr diet. Together, our data provide evidence for the coaction of ethanol and fructose with a high-fat-diet on

  16. Effect of insulin and glucose on the activity of insulin-degrading enzymes in rat liver.

    Science.gov (United States)

    Jurcovicová, J; Németh, S; Vigas, M

    1977-09-01

    The degradation of insulin by insulin protease and glutathion-insulin transhydrogenase (glutathioneproteindisulphide oxidoreductase--EC 1.8.4.2, GIT) was measured in rat liver either after replacing food and water by 15% glucose solution, or after daily insulin administration 8 U daily for 3 days or after fasting. The breakdown of radioiodinated insulin was followed by measuring the increase of TCA soluble radioactivity during incubation of cell fractions with 125I insulin at 37 degrees C. The highest GIT activity was observed in liver microsomes of rats after glucose feeding and after insulin administration, whereas enzyme activity of fasted animals did not essentially differ from corresponding values of normally fed controls. The insulin protease in cytosol of liver cells remained unchanged after these procedures. The important role of GIT in insulin degradation seems to be conclusively demonstrated.

  17. Insulin-Dependent Activation of MCH Neurons Impairs Locomotor Activity and Insulin Sensitivity in Obesity.

    Science.gov (United States)

    Hausen, A Christine; Ruud, Johan; Jiang, Hong; Hess, Simon; Varbanov, Hristo; Kloppenburg, Peter; Brüning, Jens C

    2016-12-06

    Melanin-concentrating-hormone (MCH)-expressing neurons (MCH neurons) in the lateral hypothalamus (LH) are critical regulators of energy and glucose homeostasis. Here, we demonstrate that insulin increases the excitability of these neurons in control mice. In vivo, insulin promotes phosphatidylinositol 3-kinase (PI3K) signaling in MCH neurons, and cell-type-specific deletion of the insulin receptor (IR) abrogates this response. While lean mice lacking the IR in MCH neurons (IR(ΔMCH)) exhibit no detectable metabolic phenotype under normal diet feeding, they present with improved locomotor activity and insulin sensitivity under high-fat-diet-fed, obese conditions. Similarly, obesity promotes PI3 kinase signaling in these neurons, and this response is abrogated in IR(ΔMCH) mice. In turn, acute chemogenetic activation of MCH neurons impairs locomotor activity but not insulin sensitivity. Collectively, our experiments reveal an insulin-dependent activation of MCH neurons in obesity, which contributes via distinct mechanisms to the manifestation of impaired locomotor activity and insulin resistance.

  18. Activated gammadelta T cells promote the activation of uveitogenic T cells and exacerbate EAU development.

    Science.gov (United States)

    Nian, Hong; Shao, Hui; O'Brien, Rebecca L; Born, Willi K; Kaplan, Henry J; Sun, Deming

    2011-07-29

    To determine how the activation of γδ T cells affects the generation of uveitogenic αβ T cells and the development of experimental autoimmune uveitis (EAU). γδ T cells were isolated from B6 mice immunized with the uveitogenic peptide IRBP(1-20) and αβ T cells from immunized TCR-δ(-/-) mice. Resting γδ T cells were prepared by culture of separated γδ T cells in cytokine-free medium for 3 to 5 days, when they showed downregulation of CD69 expression. Activated γδ T cells were prepared by incubating resting γδ T cells with anti-γδ TCR (GL3) for 2 days. Responder αβ T cells were cocultured with immunizing antigen and antigen-presenting cells. The numbers of antigen-specific T cells expressing IL-17 or IFN-γ were determined by intracellular staining followed by FACS analysis after stimulation, with or without the addition of purified γδ T cells. The cytokines in the culture medium were measured by ELISA. Highly enriched γδ T cells exert widely different effects on autoreactive αβ T cells in EAU, depending on the activation status of the γδ T cells. Whereas nonactivated γδ T cells had little effect on the activation of interphotoreceptor retinoid-binding protein-specific αβ T cells in vitro and in vivo, activated γδ T cells promoted the generation of uveitogenic T cells and exacerbated the development of EAU. The functional ability of γδ T cells is greatly influenced by their activation status. Activated γδ T cells exacerbate EAU through increased activation of uveitogenic T cells.

  19. Evidence that adiponectin receptor 1 activation exacerbates ischemic neuronal death

    Directory of Open Access Journals (Sweden)

    Thundyil John

    2010-08-01

    Full Text Available Abstract Background- Adiponectin is a hormone produced in and released from adipose cells, which has been shown to have anti-diabetic and anti-inflammatory actions in peripheral cells. Two cell surface adiponectin receptors (ADRs mediate the majority of the known biological actions of adiponectin. Thus far, ADR expression in the brain has been demonstrated in the arcuate and the paraventricular nucleus of hypothalamus, where its activation affects food intake. Recent findings suggest that levels of circulating adiponectin increase after an ischemic stroke, but the role of adiponectin receptor activation in stroke pathogenesis and its functional outcome is unclear. Methods- Ischemic stroke was induced in C57BL/6 mice by middle cerebral artery occlusion (MCAO for 1 h, followed by reperfusion. Primary cortical neuronal cultures were established from individual embryonic neocortex. For glucose deprivation (GD, cultured neurons were incubated in glucose-free Locke's medium for 6, 12 or 24 h. For combined oxygen and glucose deprivation (OGD, neurons were incubated in glucose-free Locke's medium in an oxygen-free chamber with 95% N2/5% CO2 atmosphere for either 3, 6, 9, 12 or 24 h. Primary neurons and brain tissues were analysed for Adiponectin and ADRs using reverse transcriptase polymerase chain reaction (RT-PCR, immunoblot and immunochemistry methods. Results- Cortical neurons express ADR1 and ADR2, and that the levels of ADR1 are increased in neurons in response to in vitro or in vivo ischemic conditions. Neurons treated with either globular or trimeric adiponectin exhibited increased vulnerability to oxygen and glucose deprivation which was associated with increased activation of a pro-apoptotic signaling cascade involving p38 mitogen-activated protein kinase (p38MAPK and AMP-activated protein kinase (AMPK. Conclusions- This study reveals a novel pathogenic role for adiponectin and adiponectin receptor activation in ischemic stroke. We show that

  20. Induction of miR-96 by Dietary Saturated Fatty Acids Exacerbates Hepatic Insulin Resistance through the Suppression of INSR and IRS-1.

    Science.gov (United States)

    Yang, Won-Mo; Min, Kyung-Ho; Lee, Wan

    2016-01-01

    Obesity is defined as the excessive accumulation of body fat that ultimately leads to chronic metabolic diseases. Diets rich in saturated fatty acids (SFA) exacerbate obesity and hepatic steatosis, which increase the risk of hepatic insulin resistance and type 2 diabetes (T2DM). Although microRNAs (miRNAs) play an important role in a range of biological processes, the implications of SFA-induced miRNAs in metabolic dysregulation, particularly in the pathogenesis of hepatic insulin resistance, are not well understood. This study investigated the implications of miR-96, which is induced strongly by SFA, in the development of hepatic insulin resistance. The liver of HFD mice and the palmitate-treated hepatocytes exhibited an impairment of insulin signaling due to the significant decrease in INSR and IRS-1 expression. According to expression profiling and qRT-PCR analysis of the miRNAs, the expression level of miR-96 was higher in hepatocytes treated with palmitate. Moreover, miR-96 was also upregulated in the liver of HFD mice. Interestingly, miR-96 targeted the 3'UTRs of INSR and IRS-1 directly, and repressed the expression of INSR and IRS-1 at the post-transcriptional level. Accordingly, the overexpression of miR-96 was found to cause a significant decrease in INSR and IRS-1 expression, thereby leading to an impairment of insulin signaling and glycogen synthesis in hepatocytes. These results reveal a novel mechanism whereby miR-96 promotes the pathogenesis of hepatic insulin resistance resulted from SFA or obesity.

  1. Overexpression of protein kinase STK25 in mice exacerbates ectopic lipid accumulation, mitochondrial dysfunction and insulin resistance in skeletal muscle

    DEFF Research Database (Denmark)

    Chursa, Urszula; Nuñez-Durán, Esther; Cansby, Emmelie

    2017-01-01

    AIMS/HYPOTHESIS: Understanding the molecular networks controlling ectopic lipid deposition and insulin responsiveness in skeletal muscle is essential for developing new strategies to treat type 2 diabetes. We recently identified serine/threonine protein kinase 25 (STK25) as a critical regulator...... of liver steatosis, hepatic lipid metabolism and whole body glucose and insulin homeostasis. Here, we assessed the role of STK25 in control of ectopic fat storage and insulin responsiveness in skeletal muscle. METHODS: Skeletal muscle morphology was studied by histological examination, exercise performance...

  2. Isoorientin reverts TNF-α-induced insulin resistance in adipocytes activating the insulin signaling pathway.

    Science.gov (United States)

    Alonso-Castro, Angel Josabad; Zapata-Bustos, Rocio; Gómez-Espinoza, Guadalupe; Salazar-Olivo, Luis A

    2012-11-01

    Isoorientin (ISO) is a plant C-glycosylflavonoid with purported antidiabetic effects but unexplored mechanisms of action. To gain insight into its antidiabetic mechanisms, we assayed nontoxic ISO concentrations on the 2-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino)-2-deoxy-d-glucose (2-NBDG) uptake by murine 3T3-F442A and human sc adipocytes. In insulin-sensitive adipocytes, ISO stimulated the 2-NBDG uptake by 210% (murine) and 67% (human), compared with insulin treatment. Notably, ISO also induced 2-NBDG uptake in murine (139%) and human (60%) adipocytes made resistant to insulin by treatment with TNF-α, compared with the incorporation induced in these cells by rosiglitazone. ISO induction of glucose uptake in adipocytes was abolished by inhibitors of the insulin signaling pathway. These inhibitors also blocked the proper phosphorylation of insulin signaling pathway components induced by ISO in both insulin-sensitive and insulin-resistant adipocytes. Additionally, ISO stimulated the transcription of genes encoding components of insulin signaling pathway in murine insulin-sensitive and insulin-resistant adipocytes. In summary, we show here that ISO exerts its antidiabetic effects by activating the insulin signaling pathway in adipocytes, reverts the insulin resistance caused in these cells by TNF-α by stimulating the proper phosphorylation of proteins in this signaling pathway, and induces the expression of genes encoding these proteins.

  3. Severe Maternal Hyperglycemia Exacerbates the Development of Insulin Resistance and Fatty Liver in the Offspring on High Fat Diet

    Directory of Open Access Journals (Sweden)

    Yong Song

    2012-01-01

    Full Text Available Background. Adverse maternal environments may predispose the offspring to metabolic syndrome in adulthoods, but the underlying mechanism has not been fully understood. Methods. Maternal hyperglycemia was induced by streptozotocin (STZ injection while control (CON rats received citrate buffer. Litters were adjusted to eight pups per dam and then weaned to standard diet. Since 13 weeks old, a subset of offspring from STZ and CON dams were switched to high fat diet (HFD for another 13 weeks. Glucose and insulin tolerance tests (GTT and ITT and insulin secretion assay were performed; serum levels of lipids and leptin were measured. Hepatic fat accumulation and islet area were evaluated through haematoxylin and eosin staining. Results. STZ offspring exhibited lower survival rate, lower birth weights, and growth inhibition which persisted throughout the study. STZ offspring on HFD showed more severe impairment in GTT and ITT, and more profound hepatic steatosis and more severe hyperlipidemia compared with CON-HFD rats. Conclusions. Offspring from diabetic dams would be prone to exhibit low birth weight and postnatal growth inhibition, but could maintain normal glucose tolerance and insulin sensitivity. HFD accelerates development of insulin resistance in the offspring of diabetic dams mainly via a compensatory response of islets.

  4. CCR2 knockout exacerbates cerulein-induced chronic pancreatitis with hyperglycemia via decreased GLP-1 receptor expression and insulin secretion.

    Science.gov (United States)

    Nakamura, Yuji; Kanai, Takanori; Saeki, Keita; Takabe, Miho; Irie, Junichiro; Miyoshi, Jun; Mikami, Yohei; Teratani, Toshiaki; Suzuki, Takahiro; Miyata, Naoteru; Hisamatsu, Tadakazu; Nakamoto, Nobuhiro; Yamagishi, Yoshiyuki; Higuchi, Hajime; Ebinuma, Hirotoshi; Hozawa, Shigenari; Saito, Hidetsugu; Itoh, Hiroshi; Hibi, Toshifumi

    2013-04-15

    Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b(+)Gr-1(low) macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b(+)/Gr-1(-) and CD11b(+)/Gr-1(high) cells, but not CD11b(+)/Gr-1(low) cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b(+)-cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.

  5. Stiffness-activated GEF-H1 expression exacerbates LPS-induced lung inflammation.

    Directory of Open Access Journals (Sweden)

    Isa Mambetsariev

    Full Text Available Acute lung injury (ALI is accompanied by decreased lung compliance. However, a role of tissue mechanics in modulation of inflammation remains unclear. We hypothesized that bacterial lipopolysacharide (LPS stimulates extracellular matrix (ECM production and vascular stiffening leading to stiffness-dependent exacerbation of endothelial cell (EC inflammatory activation and lung barrier dysfunction. Expression of GEF-H1, ICAM-1, VCAM-1, ECM proteins fibronectin and collagen, lysyl oxidase (LOX activity, interleukin-8 and activation of Rho signaling were analyzed in lung samples and pulmonary EC grown on soft (1.5 or 2.8 kPa and stiff (40 kPa substrates. LPS induced EC inflammatory activation accompanied by expression of ECM proteins, increase in LOX activity, and activation of Rho signaling. These effects were augmented in EC grown on stiff substrate. Stiffness-dependent enhancement of inflammation was associated with increased expression of Rho activator, GEF-H1. Inhibition of ECM crosslinking and stiffening by LOX suppression reduced EC inflammatory activation and GEF-H1 expression in response to LPS. In vivo, LOX inhibition attenuated LPS-induced expression of GEF-H1 and lung dysfunction. These findings present a novel mechanism of stiffness-dependent exacerbation of vascular inflammation and escalation of ALI via stimulation of GEF-H1-Rho pathway. This pathway represents a fundamental mechanism of positive feedback regulation of inflammation.

  6. Transgenic silkworms expressing human insulin receptors for evaluation of therapeutically active insulin receptor agonists.

    Science.gov (United States)

    Matsumoto, Yasuhiko; Ishii, Masaki; Ishii, Kenichi; Miyaguchi, Wataru; Horie, Ryo; Inagaki, Yoshinori; Hamamoto, Hiroshi; Tatematsu, Ken-ichiro; Uchino, Keiro; Tamura, Toshiki; Sezutsu, Hideki; Sekimizu, Kazuhisa

    2014-12-12

    We established a transgenic silkworm strain expressing the human insulin receptor (hIR) using the GAL4/UAS system. Administration of human insulin to transgenic silkworms expressing hIR decreased hemolymph sugar levels and facilitated Akt phosphorylation in the fat body. The decrease in hemolymph sugar levels induced by injection of human insulin in the transgenic silkworms expressing hIR was blocked by co-injection of wortmannin, a phosphoinositide 3-kinase inhibitor. Administration of bovine insulin, an hIR ligand, also effectively decreased sugar levels in the transgenic silkworms. These findings indicate that functional hIRs that respond to human insulin were successfully induced in the transgenic silkworms. We propose that the humanized silkworm expressing hIR is useful for in vivo evaluation of the therapeutic activities of insulin receptor agonists. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Sarcopenia exacerbates obesity-associated insulin resistance and dysglycemia: findings from the National Health and Nutrition Examination Survey III.

    Directory of Open Access Journals (Sweden)

    Preethi Srikanthan

    2010-05-01

    Full Text Available BACKGROUND: Sarcopenia often co-exists with obesity, and may have additive effects on insulin resistance. Sarcopenic obese individuals could be at increased risk for type 2 diabetes. We performed a study to determine whether sarcopenia is associated with impairment in insulin sensitivity and glucose homeostasis in obese and non-obese individuals. METHODOLOGY: We performed a cross-sectional analysis of National Health and Nutrition Examination Survey III data utilizing subjects of 20 years or older, non-pregnant (N = 14,528. Sarcopenia was identified from bioelectrical impedance measurement of muscle mass. Obesity was identified from body mass index. Outcomes were homeostasis model assessment of insulin resistance (HOMA IR, glycosylated hemoglobin level (HbA1C, and prevalence of pre-diabetes (6.0≤ HbA1C<6.5 and not on medication and type 2 diabetes. Covariates in multiple regression were age, educational level, ethnicity and sex. PRINCIPAL FINDINGS: Sarcopenia was associated with insulin resistance in non-obese (HOMA IR ratio 1.39, 95% confidence interval (CI 1.26 to 1.52 and obese individuals (HOMA-IR ratio 1.16, 95% CI 1.12 to 1.18. Sarcopenia was associated with dysglycemia in obese individuals (HbA1C ratio 1.021, 95% CI 1.011 to 1.043 but not in non-obese individuals. Associations were stronger in those under 60 years of age. We acknowledge that the cross-sectional study design limits our ability to draw causal inferences. CONCLUSIONS: Sarcopenia, independent of obesity, is associated with adverse glucose metabolism, and the association is strongest in individuals under 60 years of age, which suggests that low muscle mass may be an early predictor of diabetes susceptibility. Given the increasing prevalence of obesity, further research is urgently needed to develop interventions to prevent sarcopenic obesity and its metabolic consequences.

  8. Determinants of change in physical activity during moderate-to-severe COPD exacerbation

    Directory of Open Access Journals (Sweden)

    Esteban C

    2016-02-01

    Full Text Available Cristóbal Esteban,1,2 José M Quintana,2,3 Susana Garcia-Gutierrez,2,3 Ane Anton-Ladislao,3 Nerea Gonzalez,2,3 Marisa Baré,2,4 Nerea Fernández de Larrea,2,5 Francisco Rivas-Ruiz2,6 For the IRYSS-COPD group 1Respiratory Department, Hospital Galdakao-Usansolo, Bizkaia; 2Red de Investigación en Servicios Sanitarios y Enfermedades Crónicas (REDISSEC, Galdakao; 3Research Unit, Hospital Galdakao-Usansolo, Bizkaia; 4Unit of Clinical Epidemiology, Corporacio Parc Tauli, Barcelona; 5Health Department, Madrid; 6Research Unit, Hospital Costa del Sol, Mabella, Málaga, Spain Background: Data are scarce on patient physical activity (PA level during exacerbations of chronic obstructive pulmonary disease (eCOPD. The objective of the study was to evaluate the level and determinants of change in PA during an eCOPD. Materials and methods: We conducted a prospective cohort study with recruitment from emergency departments (EDs of 16 participating hospitals from June 2008 to September 2010. Data were recorded on socioeconomic characteristics, dyspnea, forced expiratory volume in 1 second (FEV1%, comorbidities, health-related quality of life, factors related to exacerbation, and PA in a stable clinical condition and during the eCOPD episode. Results: We evaluated 2,487 patients. Common factors related to the change in PA during hospital admission or 7 days after discharge to home from the ED were lower PA at baseline and during the first 24 hours after the index evaluation. Age, quality of life, living alone, length of hospital stay, and use of anticholinergic or systemic corticosteroids in treating the exacerbation were associated with the change in PA among hospitalized patients. Predictors of change among patients not admitted to hospital were baseline FEV1% and dyspnea at rest on ED arrival. Conclusion: Among the patients evaluated in an ED for an eCOPD, the level and change in PA was markedly variable. Factors associated with exacerbation (PA 24 hours

  9. Berberine inhibits PTP1B activity and mimics insulin action.

    Science.gov (United States)

    Chen, Chunhua; Zhang, Yuebo; Huang, Cheng

    2010-07-02

    Type 2 diabetes patients show defects in insulin signal transduction that include lack of insulin receptor, decrease in insulin stimulated receptor tyrosine kinase activity and receptor-mediated phosphorylation of insulin receptor substrates (IRSs). A small molecule that could target insulin signaling would be of significant advantage in the treatment of diabetes. Berberine (BBR) has recently been shown to lower blood glucose levels and to improve insulin resistance in db/db mice partly through the activation of AMP-activated protein kinase (AMPK) signaling and induction of phosphorylation of insulin receptor (IR). However, the underlying mechanism remains largely unknown. Here we report that BBR mimics insulin action by increasing glucose uptake ability by 3T3-L1 adipocytes and L6 myocytes in an insulin-independent manner, inhibiting phosphatase activity of protein tyrosine phosphatase 1B (PTP1B), and increasing phosphorylation of IR, IRS1 and Akt in 3T3-L1 adipocytes. In diabetic mice, BBR lowers hyperglycemia and improves impaired glucose tolerance, but does not increase insulin release and synthesis. The results suggest that BBR represents a different class of anti-hyperglycemic agents.

  10. Phenobarbital and Insulin Reciprocate Activation of the Nuclear Receptor Constitutive Androstane Receptor through the Insulin Receptor.

    Science.gov (United States)

    Yasujima, Tomoya; Saito, Kosuke; Moore, Rick; Negishi, Masahiko

    2016-05-01

    Phenobarbital (PB) antagonized insulin to inactivate the insulin receptor and attenuated the insulin receptor downstream protein kinase B (AKT)-forkhead box protein O1 and extracellular signal-regulated kinase 1/2 signals in mouse primary hepatocytes and HepG2 cells. Hepatic AKT began dephosphorylation in an early stage of PB treatment, and blood glucose levels transiently increased in both wild-type and constitutive androstane receptor (CAR) knockout (KO) mice. On the other hand, blood glucose levels increased in wild-type mice, but not KO mice, in later stages of PB treatment. As a result, PB, acting as an insulin receptor antagonist, elicited CAR-independent increases and CAR-dependent decreases of blood glucose levels at these different stages of treatment, respectively. Reciprocally, insulin activation of the insulin receptor repressed CAR activation and induction of its target CYP2B6 gene in HepG2 cells. Thus, PB and insulin cross-talk through the insulin receptor to regulate glucose and drug metabolism reciprocally.

  11. Physical exercise exacerbates memory deficits induced by intracerebroventricular STZ but improves insulin regulation of H₂O₂ production in mice synaptosomes.

    Science.gov (United States)

    Muller, Alexandre P; Zimmer, Eduardo Rigon; Kalinine, Eduardo; Haas, Clarissa B; Oses, Jean Pierre; Martimbianco de Assis, Adriano; Galina, Antonio; Souza, Diogo O; Portela, Luis Valmor

    2012-01-01

    Insulin brain resistant state is associated with cognitive deficits and Alzheimer's disease by mechanisms that may involve mitochondrial damage and oxidative stress. Conversely, physical exercise improves cognitive function and brain insulin signaling. The intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) in rodents is an established model of insulin-resistant brain state. This study evaluates the effects of physical exercise on memory performance of i.c.v., STZ-treated mice(1 and 3 mg/kg) and whether insulin (50 and 100 ng/ml) modulates mitochondrial H₂O₂ generation in synaptosomes. S100B levels and SOD and CAT activities were assessed as markers of brain damage caused by STZ. Sedentary and exercise vehicle-treated mice demonstrated similar performance in object recognition memory task. In the water maze test, exercise vehicle-treated mice showed improvement performance in the acquisition and retrieval phases. The administration of STZ (1 mg/kg) before thirty days of voluntary physical exercise protocol impaired recognition and spatial memory only in exercised mice, whereas STZ (3 mg/kg) impaired the performance of sedentary and exercise groups. Moreover, STZ (3 mg/kg) increased hippocampal S100B levels in both groups and SOD/CAT ratio in the sedentary animals. Insulin decreased synaptosomal H₂O₂ production in exercised compared to sedentary mice; however, both STZ doses abolished this effect. Normal brain insulin signaling is mechanistically involved in the improvement of cognitive function induced by exercise through the regulation of mitochondrial H₂O₂ production. However, a prior blockade of brain insulin signaling with STZ abolished the benefits of exercise on memory performance and mitochondrial H₂O₂ regulation.

  12. Activation of proteinase 3 contributes to Non-alcoholic Fatty Liver Disease (NAFLD) and insulin resistance.

    Science.gov (United States)

    Toonen, Erik J M; Mirea, Andreea-Manuela; Tack, Cees J; Stienstra, Rinke; Ballak, Dov B; van Diepen, Janna A; Hijmans, Anneke; Chavakis, Triantafyllos; Dokter, Wim H; Pham, Christine T N; Netea, Mihai G; Dinarello, Charles A; Joosten, Leo A B

    2016-05-24

    Activation of inflammatory pathways is known to accompany development of obesity-induced non-alcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes. In addition to caspase-1, the neutrophil serine proteases proteinase 3, neutrophil elastase and cathepsin G are able to process the inactive pro-inflammatory mediators IL-1β and IL-18 to their bioactive forms, thereby regulating inflammatory responses. In the present study, we investigated whether proteinase 3 is involved in obesity-induced development of insulin resistance and NAFLD. We investigated the development of NAFLD and insulin resistance in mice deficient for neutrophil elastase/proteinase 3 and neutrophil elastase/cathepsin G and in wild-type mice treated with the neutrophil serine proteinase inhibitor human alpha-1 antitrypsin. Expression profiling of metabolically relevant tissues obtained from insulin resistant mice showed that expression of proteinase 3 was specifically upregulated in the liver, whereas neutrophil elastase, cathepsin G and caspase-1 were not. Neutrophil elastase/proteinase 3 deficient mice showed strongly reduced levels of lipids in the liver after fed a high fat diet. Moreover, these mice were resistant to high fat diet-induced weight gain, inflammation and insulin resistance. Injection of proteinase 3 exacerbated insulin resistance in caspase-1(-/-) mice, indicating that proteinase 3 acts independently of caspase-1. Treatment with alpha-1 antitrypsin during the last 10 days of a 16 week high fat diet reduced hepatic lipid content and decreased fasting glucose levels. We conclude that proteinase 3 is involved in NAFLD and insulin resistance and that inhibition of proteinase 3 may have therapeutic potential.

  13. Chronic Toxoplasma gondii in Nurr1-null heterozygous mice exacerbates elevated open field activity.

    Directory of Open Access Journals (Sweden)

    Jeffrey B Eells

    Full Text Available Latent infection with Toxoplasma gondii is common in humans (approximately 30% of the global population and is a significant risk factor for schizophrenia. Since prevalence of T. gondii infection is far greater than prevalence of schizophrenia (0.5-1%, genetic risk factors are likely also necessary to contribute to schizophrenia. To test this concept in an animal model, Nurr1-null heterozygous (+/- mice and wild-type (+/+ mice were evaluate using an emergence test, activity in an open field and with a novel object, response to bobcat urine and prepulse inhibition of the acoustic startle response (PPI prior to and 6 weeks after infection with T. gondii. In the emergence test, T. gondii infection significantly decreased the amount of time spent in the cylinder. Toxoplasma gondii infection significantly elevated open field activity in both +/+ and +/- mice but this increase was significantly exacerbated in +/- mice. T. gondii infection reduced PPI in male +/- mice but this was not statistically significant. Aversion to bobcat urine was abolished by T. gondii infection in +/+ mice. In female +/- mice, aversion to bobcat urine remained after T. gondii infection while the male +/- mice showed no aversion to bobcat urine. Antibody titers of infected mice were a critical variable associated with changes in open field activity, such that an inverted U shaped relationship existed between antibody titers and the percent change in open field activity with a significant increase in activity at low and medium antibody titers but no effect at high antibody titers. These data demonstrate that the Nurr1 +/- genotype predisposes mice to T. gondii-induced alterations in behaviors that involve dopamine neurotransmission and are associated with symptoms of schizophrenia. We propose that these alterations in murine behavior were due to further exacerbation of the altered dopamine neurotransmission in Nurr1 +/- mice.

  14. Antihyperglycemic and insulin secretagogue activities of Abrus precatorius leaf extract

    Directory of Open Access Journals (Sweden)

    Balekari Umamahesh

    2016-01-01

    Full Text Available Aim: Abrus precatorius leaves methanolic extract (APME was evaluated for in vivo antihyperglycemic activity and in vitro insulinotropic effect. Materials and Methods: In vivo antihyperglycemic and insulin secretagogue activities were assessed in streptozotocin-induced diabetic rats by oral administration of APME (200 mg/kg body weight [bw] for 28 days. In vitro insulin secretion mechanisms were studied using mouse insulinoma beta cells (MIN6-β. In vivo body weight and blood glucose and in vivo and in vitro insulin levels were estimated. Results: In diabetic rats, APME treatment significantly restored body weight (26.39%, blood glucose (32.39%, and insulin levels (73.95% in comparison to diabetic control rats. In MIN6-β cells, APME potentiated insulin secretion in a dependent manner of glucose (3–16.7 mM and extract (5–500 μg/mL concentration. Insulin secretagogue effect was demonstrated in the presence of 3-isobutyl-1-methyl xanthine, glibenclamide, elevated extracellular calcium, and K+ depolarized media. Insulin release was reduced in the presence of nifedipine, ethylene glycol tetra acetic acid (calcium blocking agents, and diazoxide (potassium channel opener. Conclusion: The study suggests that APME antihyperglycemic activity might involve the insulin secretagogue effect by pancreatic beta cells physiological pathways via K+-ATP channel dependent and independently, along with an effect on Ca2+ channels.

  15. Curcumin improves high glucose-induced INS-1 cell insulin resistance via activation of insulin signaling.

    Science.gov (United States)

    Song, Zhenfeng; Wang, Huan; Zhu, Lin; Han, Mingbao; Gao, Yuan; Du, Yu; Wen, Ying

    2015-02-01

    Curcumin is a yellow pigment isolated from Corcuma longan. This research investigates the improvement of curcumin on INS-1 cells with insulin resistance induced by high glucose. INS-1 cells were treated with high glucose (30 mmol L(-1)) for 48 h. Subsequently, the medium was replaced with curcumin for 24 h. Curcumin effectively increased insulin gene expression and glucose stimulated insulin secretion (GSIS) in a dose-dependent manner. Furthermore, the molecular mechanism of curcumin-induced insulin expression and secretion in high glucose-induced INS-1 cells was investigated in this study. Curcumin increased the expression of glucose transporter 2 (GLUT2) and phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS1), phosphatidylinositol-3-kinase (PI3K) and AKT in the INS-1 cells. Moreover, curcumin stimulation increased the expression of PDX-1 and GCK. This investigation suggests that curcumin prevented high glucose-reduced insulin expression and secretion through activation of the PI3K/Akt/GLUT2 pathway in INS-1 cells.

  16. Thiazide diuretics exacerbate fructose-induced metabolic syndrome.

    Science.gov (United States)

    Reungjui, Sirirat; Roncal, Carlos A; Mu, Wei; Srinivas, Titte R; Sirivongs, Dhavee; Johnson, Richard J; Nakagawa, Takahiko

    2007-10-01

    Fructose is a commonly used sweetener associated with diets that increase the prevalence of metabolic syndrome. Thiazide diuretics are frequently used in these patients for treatment of hypertension, but they also exacerbate metabolic syndrome. Rats on high-fructose diets that are given thiazides exhibit potassium depletion and hyperuricemia. Potassium supplementation improves their insulin resistance and hypertension, whereas allopurinol reduces serum levels of uric acid and ameliorates hypertension, hypertriglyceridemia, hyperglycemia, and insulin resistance. Both potassium supplementation and treatment with allopurinol also increase urinary nitric oxide excretion. We suggest that potassium depletion and hyperuricemia in rats exacerbates endothelial dysfunction and lowers the bioavailability of nitric oxide, which blocks insulin activity and causes insulin resistance during thiazide usage. Addition of potassium supplements and allopurinol with thiazides might be helpful in the management of metabolic syndrome.

  17. Validation of Algorithms for Basal Insulin Rate Reductions in Type 1 Diabetic Patients Practising Physical Activity

    Science.gov (United States)

    2013-04-19

    Type 1 Diabetes With a Subcutaneous Insulin Pump; Adjustment of the Recommended Basal Insulin Flow Rate in the Event of Physical Activity; Adjustment of the Recommended Prandial Insulin in the Event of Physical Activity

  18. Antihyperglycemic and Insulin Secretagogue Activities of Abrus precatorius Leaf Extract

    Science.gov (United States)

    Umamahesh, Balekari; Veeresham, Ciddi

    2016-01-01

    Aim: Abrus precatorius leaves methanolic extract (APME) was evaluated for in vivo antihyperglycemic activity and in vitro insulinotropic effect. Materials and Methods: In vivo antihyperglycemic and insulin secretagogue activities were assessed in streptozotocin-induced diabetic rats by oral administration of APME (200 mg/kg body weight [bw]) for 28 days. In vitro insulin secretion mechanisms were studied using mouse insulinoma beta cells (MIN6-β). In vivo body weight and blood glucose and in vivo and in vitro insulin levels were estimated. Results: In diabetic rats, APME treatment significantly restored body weight (26.39%), blood glucose (32.39%), and insulin levels (73.95%) in comparison to diabetic control rats. In MIN6-β cells, APME potentiated insulin secretion in a dependent manner of glucose (3–16.7 mM) and extract (5–500 μg/mL) concentration. Insulin secretagogue effect was demonstrated in the presence of 3-isobutyl-1-methyl xanthine, glibenclamide, elevated extracellular calcium, and K+ depolarized media. Insulin release was reduced in the presence of nifedipine, ethylene glycol tetra acetic acid (calcium blocking agents), and diazoxide (potassium channel opener). Conclusion: The study suggests that APME antihyperglycemic activity might involve the insulin secretagogue effect by pancreatic beta cells physiological pathways via K+-ATP channel dependent and independently, along with an effect on Ca2+ channels. SUMMARY Abrus precatorius leaves methanolic extract (APME) showed a significant anti hyperglycemic and insulin secretagogue activities in streptozotocin induced diabetic rats. Also demonstrated a potent In vitro insulin secretagogue effect in mouse insulinoma beta cells (MIN6-β)APME treatment significantly restored body weight (26.39%), reduced blood glucose (32.39%) and enhanced circulatory insulin levels (73.95%) in diabetic ratsAPME demonstrated glucose and extract dose dependent insulin secretionInsulin secretagogue effect was demonstrated

  19. Saturated lipids decrease mitofusin 2 leading to endoplasmic reticulum stress activation and insulin resistance in hypothalamic cells.

    Science.gov (United States)

    Diaz, Brenda; Fuentes-Mera, Lizeth; Tovar, Armando; Montiel, Teresa; Massieu, Lourdes; Martínez-Rodríguez, Herminia Guadalupe; Camacho, Alberto

    2015-11-19

    Endoplasmic reticulum (ER) and mitochondria dysfunction contribute to insulin resistance generation during obesity and diabetes. ER and mitochondria interact through Mitofusin 2 (MTF2), which anchors in the outer mitochondrial and ER membranes regulating energy metabolism. Ablation of MTF2 leads to ER stress activation and insulin resistance. Here we determine whether lipotoxic insult induced by saturated lipids decreases MTF2 expression leading to ER stress response in hypothalamus and its effects on insulin sensitivity using in vitro and in vivo models. We found that lipotoxic stimulation induced by palmitic acid, but not the monounsaturated palmitoleic acid, decreases MTF2 protein levels in hypothalamic mHypoA-CLU192 cells. Also, palmitic acid incubation activates ER stress response evidenced by increase in the protein levels of GRP78/BIP marker at later stage than MTF2 downregulation. Additionally, we found that MTF2 alterations induced by palmitic, but not palmitoleic, stimulation exacerbate insulin resistance in hypothalamic cells. Insulin resistance induced by palmitic acid is prevented by pre-incubation of the anti-inflammatory and the ER stress release reagents, sodium salicylate and 4 phenylbutirate, respectively. Finally, we demonstrated that lipotoxic insult induced by high fat feeding to mice decreases MTF2 proteins levels in arcuate nucleus of hypothalamus. Our data indicate that saturated lipids modulate MTF2 expression in hypothalamus coordinating the ER stress response and the susceptibility to insulin resistance.

  20. Neutrophil extracellular traps that are not degraded in systemic lupus erythematosus activate complement exacerbating the disease.

    Science.gov (United States)

    Leffler, Jonatan; Martin, Myriam; Gullstrand, Birgitta; Tydén, Helena; Lood, Christian; Truedsson, Lennart; Bengtsson, Anders A; Blom, Anna M

    2012-04-01

    Ongoing inflammation including activation of the complement system is a hallmark of systemic lupus erythematosus (SLE). Antimicrobial neutrophil extracellular traps (NETs) are composed of secreted chromatin that may act as a source of autoantigens typical for SLE. In this study, we investigated how complement interacts with NETs and how NET degradation is affected by complement in SLE patients. We found that sera from a subset of patients with active SLE had a reduced ability to degrade in vitro-generated NETs, which was mostly restored when these patients were in remission. Patients that failed to degrade NETs had a more active disease and they also displayed lower levels of complement proteins C4 and C3 in blood. We discovered that NETs activated complement in vitro and that deposited C1q inhibited NET degradation including a direct inhibition of DNase-I by C1q. Complement deposition on NETs may facilitate autoantibody production, and indeed, Abs against NETs and NET epitopes were more pronounced in patients with impaired ability to degrade NETs. NET-bound autoantibodies inhibited degradation but also further increased C1q deposition, potentially exacerbating the disease. Thus, NETs are a potent complement activator, and this interaction may play an important role in SLE. Targeting complement with inhibitors or by removing complement activators such as NETs could be beneficial for patients with SLE.

  1. Mechanisms of macrophage activation in obesity-induced insulin resistance

    OpenAIRE

    Odegaard, Justin I.; Chawla, Ajay

    2008-01-01

    Chronic inflammation is now recognized as a key step in the pathogenesis of obesity-induced insulin resistance and type 2 diabetes mellitus. This low-grade inflammation is mediated by the inflammatory (classical) activation of recruited and resident macrophages that populate metabolic tissues, including adipose tissue and liver. These findings have led to the concept that infiltration and activation of adipose tissue macrophages is causally linked to obesity-induced insulin resistance. Studie...

  2. Peptidyl arginine deiminase-4 activation exacerbates kidney ischemia-reperfusion injury.

    Science.gov (United States)

    Ham, Ahrom; Rabadi, May; Kim, Mihwa; Brown, Kevin M; Ma, Zhe; D'Agati, Vivette; Lee, H Thomas

    2014-11-01

    Peptidyl arginine deiminase (PAD)4 is a nuclear enzyme that catalyzes the posttranslational conversion of arginine residues to citrulline. Posttranslational protein citrullination has been implicated in several inflammatory autoimmune diseases, including rheumatoid arthritis, colitis, and multiple sclerosis. Here, we tested the hypothesis that PAD4 contributes to ischemic acute kidney injury (AKI) by exacerbating the inflammatory response after renal ischemia-reperfusion (I/R). Renal I/R injury in mice increased PAD4 activity as well as PAD4 expression in the mouse kidney. After 30 min of renal I/R, vehicle-treated mice developed severe AKI with large increases in plasma creatinine. In contrast, mice pretreated with PAD4 inhibitors (2-chloroamidine or streptonigrin) had significantly reduced renal I/R injury. Further supporting a critical role for PAD4 in generating ischemic AKI, mice pretreated with recombinant human PAD4 (rPAD4) protein and subjected to mild (20 min) renal I/R developed exacerbated ischemic AKI. Consistent with the hypothesis that PAD4 regulates renal tubular inflammation after I/R, mice treated with a PAD4 inhibitor had significantly reduced renal neutrophil chemotactic cytokine (macrophage inflammatory protein-2 and keratinocyte-derived cytokine) expression and had decreased neutrophil infiltration. Furthermore, mice treated with rPAD4 had significantly increased renal tubular macrophage inflammatory protein-2 and keratinocyte-derived cytokine expression as well as increased neutrophil infiltration and necrosis. Finally, cultured mouse kidney proximal tubules treated with rPAD4 had significantly increased proinflammatory chemokine expression compared with vehicle-treated cells. Taken together, our results suggest that PAD4 plays a critical role in renal I/R injury by increasing renal tubular inflammatory responses and neutrophil infiltration after renal I/R.

  3. Designed Inhibitors of Insulin-Degrading Enzyme Regulate the Catabolism and Activity of Insulin

    Science.gov (United States)

    Leissring, Malcolm A.; Malito, Enrico; Hedouin, Sabrine; Reinstatler, Lael; Sahara, Tomoko; Abdul-Hay, Samer O.; Choudhry, Shakeel; Maharvi, Ghulam M.; Fauq, Abdul H.; Huzarska, Malwina; May, Philip S.; Choi, Sungwoon; Logan, Todd P.; Turk, Benjamin E.; Cantley, Lewis C.; Manolopoulou, Marika; Tang, Wei-Jen; Stein, Ross L.; Cuny, Gregory D.; Selkoe, Dennis J.

    2010-01-01

    Background Insulin is a vital peptide hormone that is a central regulator of glucose homeostasis, and impairments in insulin signaling cause diabetes mellitus. In principle, it should be possible to enhance the activity of insulin by inhibiting its catabolism, which is mediated primarily by insulin-degrading enzyme (IDE), a structurally and evolutionarily distinctive zinc-metalloprotease. Despite interest in pharmacological inhibition of IDE as an attractive anti-diabetic approach dating to the 1950s, potent and selective inhibitors of IDE have not yet emerged. Methodology/Principal Findings We used a rational design approach based on analysis of combinatorial peptide mixtures and focused compound libraries to develop novel peptide hydroxamic acid inhibitors of IDE. The resulting compounds are ∼106 times more potent than existing inhibitors, non-toxic, and surprisingly selective for IDE vis-à-vis conventional zinc-metalloproteases. Crystallographic analysis of an IDE-inhibitor complex reveals a novel mode of inhibition based on stabilization of IDE's “closed,” inactive conformation. We show further that pharmacological inhibition of IDE potentiates insulin signaling by a mechanism involving reduced catabolism of internalized insulin. Conclusions/Significance The inhibitors we describe are the first to potently and selectively inhibit IDE or indeed any member of this atypical zinc-metalloprotease superfamily. The distinctive structure of IDE's active site, and the mode of action of our inhibitors, suggests that it may be possible to develop inhibitors that cross-react minimally with conventional zinc-metalloproteases. Significantly, our results reveal that insulin signaling is normally regulated by IDE activity not only extracellularly but also within cells, supporting the longstanding view that IDE inhibitors could hold therapeutic value for the treatment of diabetes. PMID:20498699

  4. Designed Inhibitors of Insulin-Degrading Enzyme Regulate the Catabolism and Activity of Insulin

    Energy Technology Data Exchange (ETDEWEB)

    Leissring, Malcolm A.; Malito, Enrico; Hedouin, Sabrine; Reinstatler, Lael; Sahara, Tomoko; Abdul-Hay, Samer O.; Choudhry, Shakeel; Maharvi, Ghulam M.; Fauq, Abdul H.; Huzarska, Malwina; May, Philip S.; Choi, Sungwoon; Logan, Todd P.; Turk, Benjamin E.; Cantley, Lewis C.; Manolopoulou, Marika; Tang, Wei-Jen; Stein, Ross L.; Cuny, Gregory D.; Selkoe, Dennis J. (Harvard-Med); (BWH); (Yale-MED); (Scripps); (UC); (Mayo)

    2010-09-20

    Insulin is a vital peptide hormone that is a central regulator of glucose homeostasis, and impairments in insulin signaling cause diabetes mellitus. In principle, it should be possible to enhance the activity of insulin by inhibiting its catabolism, which is mediated primarily by insulin-degrading enzyme (IDE), a structurally and evolutionarily distinctive zinc-metalloprotease. Despite interest in pharmacological inhibition of IDE as an attractive anti-diabetic approach dating to the 1950s, potent and selective inhibitors of IDE have not yet emerged. We used a rational design approach based on analysis of combinatorial peptide mixtures and focused compound libraries to develop novel peptide hydroxamic acid inhibitors of IDE. The resulting compounds are {approx} 10{sup 6} times more potent than existing inhibitors, non-toxic, and surprisingly selective for IDE vis-a-vis conventional zinc-metalloproteases. Crystallographic analysis of an IDE-inhibitor complex reveals a novel mode of inhibition based on stabilization of IDE's 'closed,' inactive conformation. We show further that pharmacological inhibition of IDE potentiates insulin signaling by a mechanism involving reduced catabolism of internalized insulin. Conclusions/Significance: The inhibitors we describe are the first to potently and selectively inhibit IDE or indeed any member of this atypical zinc-metalloprotease superfamily. The distinctive structure of IDE's active site, and the mode of action of our inhibitors, suggests that it may be possible to develop inhibitors that cross-react minimally with conventional zinc-metalloproteases. Significantly, our results reveal that insulin signaling is normally regulated by IDE activity not only extracellularly but also within cells, supporting the longstanding view that IDE inhibitors could hold therapeutic value for the treatment of diabetes.

  5. Designed inhibitors of insulin-degrading enzyme regulate the catabolism and activity of insulin.

    Directory of Open Access Journals (Sweden)

    Malcolm A Leissring

    Full Text Available BACKGROUND: Insulin is a vital peptide hormone that is a central regulator of glucose homeostasis, and impairments in insulin signaling cause diabetes mellitus. In principle, it should be possible to enhance the activity of insulin by inhibiting its catabolism, which is mediated primarily by insulin-degrading enzyme (IDE, a structurally and evolutionarily distinctive zinc-metalloprotease. Despite interest in pharmacological inhibition of IDE as an attractive anti-diabetic approach dating to the 1950s, potent and selective inhibitors of IDE have not yet emerged. METHODOLOGY/PRINCIPAL FINDINGS: We used a rational design approach based on analysis of combinatorial peptide mixtures and focused compound libraries to develop novel peptide hydroxamic acid inhibitors of IDE. The resulting compounds are approximately 10(6 times more potent than existing inhibitors, non-toxic, and surprisingly selective for IDE vis-à-vis conventional zinc-metalloproteases. Crystallographic analysis of an IDE-inhibitor complex reveals a novel mode of inhibition based on stabilization of IDE's "closed," inactive conformation. We show further that pharmacological inhibition of IDE potentiates insulin signaling by a mechanism involving reduced catabolism of internalized insulin. CONCLUSIONS/SIGNIFICANCE: The inhibitors we describe are the first to potently and selectively inhibit IDE or indeed any member of this atypical zinc-metalloprotease superfamily. The distinctive structure of IDE's active site, and the mode of action of our inhibitors, suggests that it may be possible to develop inhibitors that cross-react minimally with conventional zinc-metalloproteases. Significantly, our results reveal that insulin signaling is normally regulated by IDE activity not only extracellularly but also within cells, supporting the longstanding view that IDE inhibitors could hold therapeutic value for the treatment of diabetes.

  6. Border Patrol Gone Awry: Lung NKT Cell Activation by Francisella tularensis Exacerbates Tularemia-Like Disease.

    Science.gov (United States)

    Hill, Timothy M; Gilchuk, Pavlo; Cicek, Basak B; Osina, Maria A; Boyd, Kelli L; Durrant, Douglas M; Metzger, Dennis W; Khanna, Kamal M; Joyce, Sebastian

    2015-06-01

    The respiratory mucosa is a major site for pathogen invasion and, hence, a site requiring constant immune surveillance. The type I, semi-invariant natural killer T (NKT) cells are enriched within the lung vasculature. Despite optimal positioning, the role of NKT cells in respiratory infectious diseases remains poorly understood. Hence, we assessed their function in a murine model of pulmonary tularemia--because tularemia is a sepsis-like proinflammatory disease and NKT cells are known to control the cellular and humoral responses underlying sepsis. Here we show for the first time that respiratory infection with Francisella tularensis live vaccine strain resulted in rapid accumulation of NKT cells within the lung interstitium. Activated NKT cells produced interferon-γ and promoted both local and systemic proinflammatory responses. Consistent with these results, NKT cell-deficient mice showed reduced inflammatory cytokine and chemokine response yet they survived the infection better than their wild type counterparts. Strikingly, NKT cell-deficient mice had increased lymphocytic infiltration in the lungs that organized into tertiary lymphoid structures resembling induced bronchus-associated lymphoid tissue (iBALT) at the peak of infection. Thus, NKT cell activation by F. tularensis infection hampers iBALT formation and promotes a systemic proinflammatory response, which exacerbates severe pulmonary tularemia-like disease in mice.

  7. Interleukin-33 Drives Activation of Alveolar Macrophages and Airway Inflammation in a Mouse Model of Acute Exacerbation of Chronic Asthma

    Directory of Open Access Journals (Sweden)

    Melissa M. Bunting

    2013-01-01

    Full Text Available We investigated the role of interleukin-33 (IL-33 in airway inflammation in an experimental model of an acute exacerbation of chronic asthma, which reproduces many of the features of the human disease. Systemically sensitized female BALB/c mice were challenged with a low mass concentration of aerosolized ovalbumin for 4 weeks to induce chronic asthmatic inflammation and then received a single moderate-level challenge to trigger acute airway inflammation simulating an asthmatic exacerbation. The inflammatory response and expression of cytokines and activation markers by alveolar macrophages (AM were assessed, as was the effect of pretreatment with a neutralizing antibody to IL-33. Compared to chronically challenged mice, AM from an acute exacerbation exhibited significantly enhanced expression of markers of alternative activation, together with enhanced expression of proinflammatory cytokines and of cell surface proteins associated with antigen presentation. In parallel, there was markedly increased expression of both mRNA and immunoreactivity for IL-33 in the airways. Neutralization of IL-33 significantly decreased both airway inflammation and the expression of proinflammatory cytokines by AM. Collectively, these data indicate that in this model of an acute exacerbation of chronic asthma, IL-33 drives activation of AM and has an important role in the pathogenesis of airway inflammation.

  8. Interleukin-33 drives activation of alveolar macrophages and airway inflammation in a mouse model of acute exacerbation of chronic asthma.

    Science.gov (United States)

    Bunting, Melissa M; Shadie, Alexander M; Flesher, Rylie P; Nikiforova, Valentina; Garthwaite, Linda; Tedla, Nicodemus; Herbert, Cristan; Kumar, Rakesh K

    2013-01-01

    We investigated the role of interleukin-33 (IL-33) in airway inflammation in an experimental model of an acute exacerbation of chronic asthma, which reproduces many of the features of the human disease. Systemically sensitized female BALB/c mice were challenged with a low mass concentration of aerosolized ovalbumin for 4 weeks to induce chronic asthmatic inflammation and then received a single moderate-level challenge to trigger acute airway inflammation simulating an asthmatic exacerbation. The inflammatory response and expression of cytokines and activation markers by alveolar macrophages (AM) were assessed, as was the effect of pretreatment with a neutralizing antibody to IL-33. Compared to chronically challenged mice, AM from an acute exacerbation exhibited significantly enhanced expression of markers of alternative activation, together with enhanced expression of proinflammatory cytokines and of cell surface proteins associated with antigen presentation. In parallel, there was markedly increased expression of both mRNA and immunoreactivity for IL-33 in the airways. Neutralization of IL-33 significantly decreased both airway inflammation and the expression of proinflammatory cytokines by AM. Collectively, these data indicate that in this model of an acute exacerbation of chronic asthma, IL-33 drives activation of AM and has an important role in the pathogenesis of airway inflammation.

  9. Rab5 activity regulates GLUT4 sorting into insulin-responsive and non-insulin-responsive endosomal compartments: a potential mechanism for development of insulin resistance.

    Science.gov (United States)

    Tessneer, Kandice L; Jackson, Robert M; Griesel, Beth A; Olson, Ann Louise

    2014-09-01

    Glucose transporter isoform 4 (GLUT4) is the insulin-responsive glucose transporter mediating glucose uptake in adipose and skeletal muscle. Reduced GLUT4 translocation from intracellular storage compartments to the plasma membrane is a cause of peripheral insulin resistance. Using a chronic hyperinsulinemia (CHI)-induced cell model of insulin resistance and Rab5 mutant overexpression, we determined these manipulations altered endosomal sorting of GLUT4, thus contributing to the development of insulin resistance. We found that CHI induced insulin resistance in 3T3-L1 adipocytes by retaining GLUT4 in a Rab5-activity-dependent compartment that is unable to equilibrate with the cell surface in response to insulin. Furthermore, CHI-mediated retention of GLUT4 in this non-insulin-responsive compartment impaired filling of the transferrin receptor (TfR)-positive and TfR-negative insulin-responsive storage compartments. Our data suggest that hyperinsulinemia may inhibit GLUT4 by chronically maintaining GLUT4 in the Rab5 activity-dependent endosomal pathway and impairing formation of the TfR-negative and TfR-positive insulin-responsive GLUT4 pools. This model suggests that an early event in the development of insulin-resistant glucose transport in adipose tissue is to alter the intracellular localization of GLUT4 to a compartment that does not efficiently equilibrate with the cell surface when insulin levels are elevated for prolonged periods of time.

  10. Exacerbation of Bloody Diarrhea as a Side Effect of Mesalamine Treatment of Active Ulcerative Colitis

    Directory of Open Access Journals (Sweden)

    Yuichi Shimodate

    2011-04-01

    Full Text Available Mesalamine has been used as the first-line therapy for the treatment of ulcerative colitis (UC because of its efficacy and fewer side effects. However, earlier study showed that mesalamine occasionally causes diarrhea. We are presenting a patient with active UC in whom bloody diarrhea accompanied by abdominal pain and fever occurred and the symptoms were aggravated after administration of mesalamine. In order to clarify the reason of symptoms aggravation, drug lymphocyte stimulation test and rechallenge trial with mesalamine were performed. The results indicated the possibility that aggravation was related to allergic reaction and was dose-dependent. Furthermore, we examined colonoscopic views but there was no remarkable change in before and after rechallenge trial. Based on the above result, the patient was diagnosed with mesalamine intolerance. In order to differentiate whether the exacerbation of bloody diarrhea is due to the side effects of the mesalamine or a true relapse of UC, taking careful history before and after increasing mesalamine dosage as well as being aware of side effects of mesalamine are required. Clinicians should be aware of diarrhea as a side effect of mesalamine particularly after onset of mesalamine formulation, change in mesalamine formulation, or change in mesalamine dose.

  11. Insulin Resistance in Alzheimer's Disease

    Science.gov (United States)

    Dineley, Kelly T; Jahrling, Jordan B; Denner, Larry

    2014-01-01

    Insulin is a key hormone regulating metabolism. Insulin binding to cell surface insulin receptors engages many signaling intermediates operating in parallel and in series to control glucose, energy, and lipids while also regulating mitogenesis and development. Perturbations in the function of any of these intermediates, which occur in a variety of diseases, cause reduced sensitivity to insulin and insulin resistance with consequent metabolic dysfunction. Chronic inflammation ensues which exacerbates compromised metabolic homeostasis. Since insulin has a key role in learning and memory as well as directly regulating ERK, a kinase required for the type of learning and memory compromised in early Alzheimer's disease (AD), insulin resistance has been identified as a major risk factor for the onset of AD. Animal models of AD or insulin resistance or both demonstrate that AD pathology and impaired insulin signaling form a reciprocal relationship. Of note are human and animal model studies geared toward improving insulin resistance that have led to the identification of the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) as an intervention tool for early AD. Strategic targeting of alternate nodes within the insulin signaling network has revealed disease-stage therapeutic windows in animal models that coalesce with previous and ongoing clinical trial approaches. Thus, exploiting the connection between insulin resistance and AD provides powerful opportunities to delineate therapeutic interventions that slow or block the pathogenesis of AD. PMID:25237037

  12. Insulin resistance in Alzheimer's disease.

    Science.gov (United States)

    Dineley, Kelly T; Jahrling, Jordan B; Denner, Larry

    2014-12-01

    Insulin is a key hormone regulating metabolism. Insulin binding to cell surface insulin receptors engages many signaling intermediates operating in parallel and in series to control glucose, energy, and lipids while also regulating mitogenesis and development. Perturbations in the function of any of these intermediates, which occur in a variety of diseases, cause reduced sensitivity to insulin and insulin resistance with consequent metabolic dysfunction. Chronic inflammation ensues which exacerbates compromised metabolic homeostasis. Since insulin has a key role in learning and memory as well as directly regulating ERK, a kinase required for the type of learning and memory compromised in early Alzheimer's disease (AD), insulin resistance has been identified as a major risk factor for the onset of AD. Animal models of AD or insulin resistance or both demonstrate that AD pathology and impaired insulin signaling form a reciprocal relationship. Of note are human and animal model studies geared toward improving insulin resistance that have led to the identification of the nuclear receptor and transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) as an intervention tool for early AD. Strategic targeting of alternate nodes within the insulin signaling network has revealed disease-stage therapeutic windows in animal models that coalesce with previous and ongoing clinical trial approaches. Thus, exploiting the connection between insulin resistance and AD provides powerful opportunities to delineate therapeutic interventions that slow or block the pathogenesis of AD. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Glucose inhibits the insulin-induced activation of the insulin-degrading enzyme in HepG2 cells.

    Science.gov (United States)

    Pivovarova, O; Gögebakan, O; Pfeiffer, A F H; Rudovich, N

    2009-08-01

    Hepatic insulin degradation decreases in type 2 diabetes. Insulin-degrading enzyme (IDE) plays a key role in insulin degradation and its gene is located in a diabetes-associated chromosomal region. We hypothesised that IDE may be regulated by insulin and/or glucose in a liver cell model. To validate the observed regulation of IDE in vivo, we analysed biopsies of human adipose tissue during different clamp experiments in men. Human hepatoma HepG2 cells were incubated in normal (1 g/l) or high (4.5 g/l) glucose medium and treated with insulin for 24 h. Catalytic activity, mRNA and protein levels of IDE were assessed. IDE mRNA levels were measured in biopsies of human subcutaneous adipose tissue before and at 240 min of hyperinsulinaemic, euglycaemic and hyperglycaemic clamps. In HepG2 cells, insulin increased IDE activity under normal glucose conditions with no change in IDE mRNA or protein levels. Under conditions of high glucose, insulin increased mRNA levels of IDE without changes in IDE activity. Both in normal and high glucose medium, insulin increased levels of the catalytically more active 15a IDE isoform compared with the 15b isoform. In subcutaneous adipose tissue, IDE mRNA levels were not significantly upregulated after euglycaemic or hyperglycaemic clamps. Insulin increases IDE activity in HepG2 cells in normal but not in high glucose conditions. This disturbance cannot be explained by corresponding alterations in IDE protein levels or IDE splicing. The loss of insulin-induced regulation of IDE activity under hyperglycaemia may contribute to the reduced insulin extraction and peripheral hyperinsulinaemia in type 2 diabetes.

  14. Complement activation, endothelial dysfunction, insulin resistance and chronic heart failure

    DEFF Research Database (Denmark)

    Bjerre, M.; Kistorp, C.; Hansen, T.K.

    2010-01-01

    CRP), endothelial activation (soluble E-selectin, sEsel)), endothelial damage/dysfunction (von Willebrand factor, vWf) and insulin resistance (IR) and prognosis in CHF remains unknown. Design. We investigated the association(s) between plasma sMAC, hsCRP, sEsel, vWf and IR (assessed by homeostatic model assessment...

  15. Ouabain exacerbates activation-induced cell death in human peripheral blood lymphocytes

    Directory of Open Access Journals (Sweden)

    Mabel B. Esteves

    2005-06-01

    Full Text Available Lymphocytes activated by mitogenic lectins display changes in transmembrane potential, an elevation in the cytoplasmic Ca2+ concentrations, proliferation and/or activation induced cell death. Low concentrations of ouabain (an inhibitor of Na+,K+-ATPase suppress mitogen-induced proliferation and increases cell death. To understand the mechanisms involved, a number of parameters were analyzed using fluorescent probes and flow cytometry. The addition of 100nM ouabain to cultures of peripheral blood lymphocytes activated with 5µg/ml phytohemagglutinin (PHA did not modify the increased expression of the Fas receptor or its ligand FasL induced by the mitogen. However, treatment with ouabain potentiated apoptosis induced by an anti-Fas agonist antibody. A synergy between ouabain and PHA was also observed with regard to plasma membrane depolarization. PHA per se did not induce dissipation of mitochondrial membrane potential but when cells were also exposed to ouabain a marked depolarization could be observed, and this was a late event. It is possible that the inhibitory effect of ouabain on activated peripheral blood lymphocytes involves the potentiation of some of the steps of the apoptotic process and reflects an exacerbation of the mechanism of activation-induced cell death.Quando linfócitos são ativados por lectinas mitogênicas apresentam mudanças do potencial de membrana, elevação das concentrações citoplasmáticas de cálcio, proliferação e/ou morte celular induzida por ativação (AICD. Concentrações baixas de ouabaína (um inibidor da Na,K-ATPase suprimem a proliferação induzida por mitógenos e aumentam a morte celular. Para entender os mecanismos envolvidos, uma série de parâmetros foram avaliados usando sondas fluorescentes e citometria de fluxo. A adição de 100nM de ouabaína para culturas de linfócitos de sangue periférico ativadas por fitohemaglutinina (PHA não modificou o aumento de expressão do receptor Fas ou de

  16. Role of Heme Oxygenase in Inflammation, Insulin-Signalling, Diabetes and Obesity

    National Research Council Canada - National Science Library

    Ndisang, Joseph Fomusi

    2010-01-01

    ... and resistin, which in turn activates the c-Jun-N-terminal kinase (JNK) and NF-κB pathways, creating a vicious cycle that exacerbates insulin resistance, type-2 diabetes and related complications...

  17. Adipocyte insulin receptor activity maintains adipose tissue mass and lifespan.

    Science.gov (United States)

    Friesen, Max; Hudak, Carolyn S; Warren, Curtis R; Xia, Fang; Cowan, Chad A

    2016-08-05

    Type 2 diabetes follows a well-defined progressive pathogenesis, beginning with insulin resistance in metabolic tissues such as the adipose. Intracellular signaling downstream of insulin receptor activation regulates critical metabolic functions of adipose tissue, including glucose uptake, lipogenesis, lipolysis and adipokine secretion. Previous studies have used the aP2 promoter to drive Cre recombinase expression in adipose tissue. Insulin receptor (IR) knockout mice created using this aP2-Cre strategy (FIRKO mice) were protected from obesity and glucose intolerance. Later studies demonstrated the promiscuity of the aP2 promoter, casting doubts upon the tissue specificity of aP2-Cre models. It is our goal to use the increased precision of the Adipoq promoter to investigate adipocyte-specific IR function. Towards this end we generated an adipocyte-specific IR knockout (AIRKO) mouse using an Adipoq-driven Cre recombinase. Here we report AIRKO mice are less insulin sensitive throughout life, and less glucose tolerant than wild-type (WT) littermates at the age of 16 weeks. In contrast to WT littermates, the insulin sensitivity of AIRKO mice is unaffected by age or dietary regimen. At any age, AIRKO mice are comparably insulin resistant to old or obese WT mice and have a significantly reduced lifespan. Similar results were obtained when these phenotypes were re-examined in FIRKO mice. We also found that the AIRKO mouse is protected from high-fat diet-induced weight gain, corresponding with a 90% reduction in tissue weight of major adipose depots compared to WT littermates. Adipose tissue mass reduction is accompanied by hepatomegaly and increased hepatic steatosis. These data indicate that adipocyte IR function is crucial to systemic energy metabolism and has profound effects on adiposity, hepatic homeostasis and lifespan. Copyright © 2016. Published by Elsevier Inc.

  18. A novel hydroxyfuroic acid compound as an insulin receptor activator – structure and activity relationship of a prenylindole moiety to insulin receptor activation

    Directory of Open Access Journals (Sweden)

    Tsai Henry J

    2009-07-01

    Full Text Available Abstract Background Diabetes Mellitus is a chronic disease and many patients of which require frequent subcutaneous insulin injection to maintain proper blood glucose levels. Due to the inconvenience of insulin administration, an orally active insulin replacement has long been a prime target for many pharmaceutical companies. Demethylasterriquinone (DMAQ B1, extracted from tropical fungus, Pseudomassaria sp., has been reported to be an orally effective agent at lowering circulating glucose levels in diabetic (db/db mice; however, the cytotoxicity associated with the quinone moiety has not been addressed thus far. Methods A series of hydroxyfuroic acid compounds were synthesized and tested for their efficacies at activating human insulin receptor. Cytotoxicity to Chinese hamster ovary cells, selectivities over insulin-like growth factor-1 (IGF-1, epidermal growth factor (EGF, and fibroblast growth factor (FGF receptors were examined in this study. Result and Conclusion This study reports a new non-quinone DMAQ B1 derivative, a hydroxyfuroic acid compound (D-410639, which is 128 fold less cytotoxic as DMAQ B1 and as potent as compound 2, a DMAQ B1 synthetic derivative from Merck, at activating human insulin receptor. D-410639 has little activation potential on IGF-1 receptor but is a moderate inhibitor to EGF receptor. Structure and activity relationship of the prenylindole moiety to insulin receptor activation is discussed.

  19. Macrophage CGI-58 Deficiency Activates ROS-Inflammasome Pathway to Promote Insulin Resistance in Mice

    Directory of Open Access Journals (Sweden)

    Hongming Miao

    2014-04-01

    Full Text Available Overnutrition activates a proinflammatory program in macrophages to induce insulin resistance (IR, but its molecular mechanisms remain incompletely understood. Here, we show that saturated fatty acid and lipopolysaccharide, two factors implicated in high-fat diet (HFD-induced IR, suppress macrophage CGI-58 expression. Macrophage-specific CGI-58 knockout (MaKO in mice aggravates HFD-induced glucose intolerance and IR, which is associated with augmented systemic/tissue inflammation and proinflammatory activation of adipose tissue macrophages. CGI-58-deficient macrophages exhibit mitochondrial dysfunction due to defective peroxisome proliferator-activated receptor (PPARγ signaling. Consequently, they overproduce reactive oxygen species (ROS to potentiate secretion of proinflammatory cytokines by activating NLRP3 inflammasome. Anti-ROS treatment or NLRP3 silencing prevents CGI-58-deficient macrophages from oversecreting proinflammatory cytokines and from inducing proinflammatory signaling and IR in the cocultured fat slices. Anti-ROS treatment also prevents exacerbation of inflammation and IR in HFD-fed MaKO mice. Our data thus establish CGI-58 as a suppressor of overnutrition-induced NLRP3 inflammasome activation in macrophages.

  20. Insulin enhances the peroxidase activity of heme by forming heme-insulin complex: Relevance to type 2 diabetes mellitus.

    Science.gov (United States)

    Huang, Yi; Yang, Zhen; Xu, Huan; Zhang, Pengfei; Gao, Zhonghong; Li, Hailing

    2017-09-01

    Evidences have implicated the involvement of heme in the type 2 diabetes mellitus (T2Dm) pathogenesis, but possible mediators linking between heme and diabetes are still poorly understood. Here, we explored a potential mechanism that linked heme, insulin and diabetes. Our results demonstrated the formation of heme-insulin complex by two classical methods, i.e. UV-vis and capillary electrophoresis-frontal analysis (CE-FA). UV-vis results implied heme binding insulin via bis-histidine sites, and CE-FA further revealed that, when insulin uses two sites binding with heme, this interaction occurs at high affinity (Kd=3.13×10(-6)M). Molecule docking supported that histidine-B5 of insulin binds with heme-Fe. In addition to that, tyrosine-B26, phenylalanine-B1 and valine-B2 are also contributed to binding heme. The binding amplified the peroxidase activity of heme itself. Under oxidative and nitrative stress, it affects pathogenesis of diabetes from two aspects: promoting insulin cross-linking that leads to permanent loss of insulin functionality on one hand, and enhancing protein tyrosine nitration that may result in inactivation of proteins associated with diabetes on the other hand. This study suggested that the enhanced peroxidase activity of heme through binding with insulin might be a previously unrecognized contributor to the pathogenesis of T2Dm in some heme-associated disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Orally active insulin mimics: where do we stand now?

    Indian Academy of Sciences (India)

    M Balasubramanyam; V Mohan

    2001-09-01

    The war against diabetes through the development of new drugs is an ongoing continuous process to counter the alarming global increase in the prevalence of diabetes and its complications, particularly in developing countries like India. Unfortunately, the speed with which our knowledge of diabetes and its effects is expanding is not matched by the availability of new drugs. Following the identification of the insulin receptor (IR), its intrinsic kinase activity and molecular cloning, many studies have looked at IR as an ideal drug target. This review summarizes in brief the latest advancements in this field with particular reference to the current situation in respect of the development of orally active insulin mimetics in the treatment of type 2 diabetes.

  2. Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

    Science.gov (United States)

    Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

    2009-01-01

    Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels.

  3. Extract of lotus leaf ( Nelumbo nucifera ) and its active constituent catechin with insulin secretagogue activity.

    Science.gov (United States)

    Huang, Chun Fa; Chen, Ya Wen; Yang, Ching Yao; Lin, Hui Yi; Way, Tzong Der; Chiang, Wenchang; Liu, Shing Hwa

    2011-02-23

    The effect of lotus leaf ( Nelumbo nucifera Gaertn.) on diabetes is unclear. We hypothesized that lotus leaf can regulate insulin secretion and blood glucose levels. The in vitro and in vivo effects of lotus leaf methanolic extract (NNE) on insulin secretion and hyperglycemia were investigated. NNE increased insulin secretion from β cells (HIT-T15) and human islets. NNE enhanced the intracellular calcium levels in β cells. NNE could also enhance phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2 and protein kinase C (PKC), which could be reversed by a PKC inhibitor. The in vivo studies showed that NNE possesses the ability to regulate blood glucose levels in fasted normal mice and high-fat-diet-induced diabetic mice. Furthermore, the in vitro and in vivo effects of the active constituents of NNE, quercetin, and catechin, on glucose-induced insulin secretion and blood glucose regulation were evaluated. Quercetin did not affect insulin secretion, but catechin significantly and dose-dependently enhanced insulin secretion. Orally administered catechin significantly reversed the glucose intolerance in high-fat-diet-induced diabetic mice. These findings suggest that NNE and its active constituent catechin are useful in the control of hyperglycemia in non-insulin-dependent diabetes mellitus through their action as insulin secretagogues.

  4. Glucose-responsive insulin activity by covalent modification with aliphatic phenylboronic acid conjugates.

    Science.gov (United States)

    Chou, Danny Hung-Chieh; Webber, Matthew J; Tang, Benjamin C; Lin, Amy B; Thapa, Lavanya S; Deng, David; Truong, Jonathan V; Cortinas, Abel B; Langer, Robert; Anderson, Daniel G

    2015-02-24

    Since its discovery and isolation, exogenous insulin has dramatically changed the outlook for patients with diabetes. However, even when patients strictly follow an insulin regimen, serious complications can result as patients experience both hyperglycemic and hypoglycemic states. Several chemically or genetically modified insulins have been developed that tune the pharmacokinetics of insulin activity for personalized therapy. Here, we demonstrate a strategy for the chemical modification of insulin intended to promote both long-lasting and glucose-responsive activity through the incorporation of an aliphatic domain to facilitate hydrophobic interactions, as well as a phenylboronic acid for glucose sensing. These synthetic insulin derivatives enable rapid reversal of blood glucose in a diabetic mouse model following glucose challenge, with some derivatives responding to repeated glucose challenges over a 13-h period. The best-performing insulin derivative provides glucose control that is superior to native insulin, with responsiveness to glucose challenge improved over a clinically used long-acting insulin derivative. Moreover, continuous glucose monitoring reveals responsiveness matching that of a healthy pancreas. This synthetic approach to insulin modification could afford both long-term and glucose-mediated insulin activity, thereby reducing the number of administrations and improving the fidelity of glycemic control for insulin therapy. The described work is to our knowledge the first demonstration of a glucose-binding modified insulin molecule with glucose-responsive activity verified in vivo.

  5. Minimum active structure of insulin-like peptide 5.

    Science.gov (United States)

    Belgi, Alessia; Bathgate, Ross A D; Kocan, Martina; Patil, Nitin; Zhang, Suode; Tregear, Geoffrey W; Wade, John D; Hossain, Mohammed Akhter

    2013-12-12

    Insulin-like peptide 5 (INSL5) is a complex two-chain peptide hormone constrained by three disulfide bonds in a pattern identical to insulin. High expression of INSL5 in the colon suggests roles in activation of colon motility and appetite control. A more recent study indicates it may have significant roles in the regulation of insulin secretion and β-cell homeostasis. This peptide thus has considerable potential for the treatment of eating disorders, obesity, and/or diabetes. However, the synthesis of INSL5 is extremely challenging either by chemical or recombinant means. The A-chain is very poorly soluble and the B-chain is highly aggregating in nature which, together, makes their postsynthesis handling and purification very difficult. Given these difficulties, we have developed a highly active INSL5 analogue that has a much simpler structure with two disulfide bonds and is thus easier to assemble compared to native INSL5. This minimized peptide represents an attractive new mimetic for investigating the functional role of INSL5.

  6. Modulation of insulin degrading enzyme activity and liver cell proliferation.

    Science.gov (United States)

    Pivovarova, Olga; von Loeffelholz, Christian; Ilkavets, Iryna; Sticht, Carsten; Zhuk, Sergei; Murahovschi, Veronica; Lukowski, Sonja; Döcke, Stephanie; Kriebel, Jennifer; de las Heras Gala, Tonia; Malashicheva, Anna; Kostareva, Anna; Lock, Johan F; Stockmann, Martin; Grallert, Harald; Gretz, Norbert; Dooley, Steven; Pfeiffer, Andreas F H; Rudovich, Natalia

    2015-01-01

    Diabetes mellitus type 2 (T2DM), insulin therapy, and hyperinsulinemia are independent risk factors of liver cancer. Recently, the use of a novel inhibitor of insulin degrading enzyme (IDE) was proposed as a new therapeutic strategy in T2DM. However, IDE inhibition might stimulate liver cell proliferation via increased intracellular insulin concentration. The aim of this study was to characterize effects of inhibition of IDE activity in HepG2 hepatoma cells and to analyze liver specific expression of IDE in subjects with T2DM. HepG2 cells were treated with 10 nM insulin for 24 h with or without inhibition of IDE activity using IDE RNAi, and cell transcriptome and proliferation rate were analyzed. Human liver samples (n = 22) were used for the gene expression profiling by microarrays. In HepG2 cells, IDE knockdown changed expression of genes involved in cell cycle and apoptosis pathways. Proliferation rate was lower in IDE knockdown cells than in controls. Microarray analysis revealed the decrease of hepatic IDE expression in subjects with T2DM accompanied by the downregulation of the p53-dependent genes FAS and CCNG2, but not by the upregulation of proliferation markers MKI67, MCM2 and PCNA. Similar results were found in the liver microarray dataset from GEO Profiles database. In conclusion, IDE expression is decreased in liver of subjects with T2DM which is accompanied by the dysregulation of p53 pathway. Prolonged use of IDE inhibitors for T2DM treatment should be carefully tested in animal studies regarding its potential effect on hepatic tumorigenesis.

  7. Disruption of inducible 6-phosphofructo-2-kinase ameliorates diet-induced adiposity but exacerbates systemic insulin resistance and adipose tissue inflammatory response.

    Science.gov (United States)

    Huo, Yuqing; Guo, Xin; Li, Honggui; Wang, Huan; Zhang, Weiyu; Wang, Ying; Zhou, Huaijun; Gao, Zhanguo; Telang, Sucheta; Chesney, Jason; Chen, Y Eugene; Ye, Jianping; Chapkin, Robert S; Wu, Chaodong

    2010-02-05

    Adiposity is commonly associated with adipose tissue dysfunction and many overnutrition-related metabolic diseases including type 2 diabetes. Much attention has been paid to reducing adiposity as a way to improve adipose tissue function and systemic insulin sensitivity. PFKFB3/iPFK2 is a master regulator of adipocyte nutrient metabolism. Using PFKFB3(+/-) mice, the present study investigated the role of PFKFB3/iPFK2 in regulating diet-induced adiposity and systemic insulin resistance. On a high-fat diet (HFD), PFKFB3(+/-) mice gained much less body weight than did wild-type littermates. This was attributed to a smaller increase in adiposity in PFKFB3(+/-) mice than in wild-type controls. However, HFD-induced systemic insulin resistance was more severe in PFKFB3(+/-) mice than in wild-type littermates. Compared with wild-type littermates, PFKFB3(+/-) mice exhibited increased severity of HFD-induced adipose tissue dysfunction, as evidenced by increased adipose tissue lipolysis, inappropriate adipokine expression, and decreased insulin signaling, as well as increased levels of proinflammatory cytokines in both isolated adipose tissue macrophages and adipocytes. In an in vitro system, knockdown of PFKFB3/iPFK2 in 3T3-L1 adipocytes caused a decrease in the rate of glucose incorporation into lipid but an increase in the production of reactive oxygen species. Furthermore, knockdown of PFKFB3/iPFK2 in 3T3-L1 adipocytes inappropriately altered the expression of adipokines, decreased insulin signaling, increased the phosphorylation states of JNK and NFkappaB p65, and enhanced the production of proinflammatory cytokines. Together, these data suggest that PFKFB3/iPFK2, although contributing to adiposity, protects against diet-induced insulin resistance and adipose tissue inflammatory response.

  8. Insulin and insulin-like growth factor I exert different effects on plasminogen activator production or cell growth in the ovine thyroid cell line OVNIS.

    Science.gov (United States)

    Degryse, B; Maisonobe, F; Hovsépian, S; Fayet, G

    1991-11-01

    Insulin and Insulin-like Growth Factor I (IGF-I) are evaluated for their capacity to affect cell proliferation and plasminogen activator (PA) activity production in an ovine thyroid cell line OVNIS. Insulin at physiological and supraphysiological doses induces cell proliferation and increases PA activity. IGF-I, which is also clearly mitogenic for these cells, surprisingly does not modulate PA activity. The results indicate that the growth promoting effect is mediated through the insulin and IGF-I receptors whereas PA activity is solely regulated via the insulin receptors.

  9. An Extended Polyanion Activation Surface in Insulin Degrading Enzyme.

    Directory of Open Access Journals (Sweden)

    Eun Suk Song

    Full Text Available Insulin degrading enzyme (IDE is believed to be the major enzyme that metabolizes insulin and has been implicated in the degradation of a number of other bioactive peptides, including amyloid beta peptide (Aβ, glucagon, amylin, and atrial natriuretic peptide. IDE is activated toward some substrates by both peptides and polyanions/anions, possibly representing an important control mechanism and a potential therapeutic target. A binding site for the polyanion ATP has previously been defined crystallographically, but mutagenesis studies suggest that other polyanion binding modes likely exist on the same extended surface that forms one wall of the substrate-binding chamber. Here we use a computational approach to define three potential ATP binding sites and mutagenesis and kinetic studies to confirm the relevance of these sites. Mutations were made at four positively charged residues (Arg 429, Arg 431, Arg 847, Lys 898 within the polyanion-binding region, converting them to polar or hydrophobic residues. We find that mutations in all three ATP binding sites strongly decrease the degree of activation by ATP and can lower basal activity and cooperativity. Computational analysis suggests conformational changes that result from polyanion binding as well as from mutating residues involved in polyanion binding. These findings indicate the presence of multiple polyanion binding modes and suggest the anion-binding surface plays an important conformational role in controlling IDE activity.

  10. Insulin enhances striatal dopamine release by activating cholinergic interneurons and thereby signals reward

    Science.gov (United States)

    Stouffer, Melissa A.; Woods, Catherine A.; Patel, Jyoti C.; Lee, Christian R.; Witkovsky, Paul; Bao, Li; Machold, Robert P.; Jones, Kymry T.; de Vaca, Soledad Cabeza; Reith, Maarten E. A.; Carr, Kenneth D.; Rice, Margaret E.

    2015-01-01

    Insulin activates insulin receptors (InsRs) in the hypothalamus to signal satiety after a meal. However, the rising incidence of obesity, which results in chronically elevated insulin levels, implies that insulin may also act in brain centres that regulate motivation and reward. We report here that insulin can amplify action potential-dependent dopamine (DA) release in the nucleus accumbens (NAc) and caudate–putamen through an indirect mechanism that involves striatal cholinergic interneurons that express InsRs. Furthermore, two different chronic diet manipulations in rats, food restriction (FR) and an obesogenic (OB) diet, oppositely alter the sensitivity of striatal DA release to insulin, with enhanced responsiveness in FR, but loss of responsiveness in OB. Behavioural studies show that intact insulin levels in the NAc shell are necessary for acquisition of preference for the flavour of a paired glucose solution. Together, these data imply that striatal insulin signalling enhances DA release to influence food choices. PMID:26503322

  11. Akt/PKB activation and insulin signaling: a novel insulin signaling pathway in the treatment of type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Mackenzie RWA

    2014-02-01

    Full Text Available Richard WA Mackenzie, Bradley T Elliott Department of Human and Health Sciences, Facility of Science and Technology, University of Westminster, London, UK Abstract: Type 2 diabetes is a metabolic disease categorized primarily by reduced insulin sensitivity, β-cell dysfunction, and elevated hepatic glucose production. Treatments reducing hyperglycemia and the secondary complications that result from these dysfunctions are being sought after. Two distinct pathways encourage glucose transport activity in skeletal muscle, ie, the contraction-stimulated pathway reliant on Ca2+/5′-monophosphate-activated protein kinase (AMPK-dependent mechanisms and an insulin-dependent pathway activated via upregulation of serine/threonine protein kinase Akt/PKB. Metformin is an established treatment for type 2 diabetes due to its ability to increase peripheral glucose uptake while reducing hepatic glucose production in an AMPK-dependent manner. Peripheral insulin action is reduced in type 2 diabetics whereas AMPK signaling remains largely intact. This paper firstly reviews AMPK and its role in glucose uptake and then focuses on a novel mechanism known to operate via an insulin-dependent pathway. Inositol hexakisphosphate (IP6 kinase 1 (IP6K1 produces a pyrophosphate group at the position of IP6 to generate a further inositol pyrophosphate, ie, diphosphoinositol pentakisphosphate (IP7. IP7 binds with Akt/PKB at its pleckstrin homology domain, preventing interaction with phosphatidylinositol 3,4,5-trisphosphate, and therefore reducing Akt/PKB membrane translocation and insulin-stimulated glucose uptake. Novel evidence suggesting a reduction in IP7 production via IP6K1 inhibition represents an exciting therapeutic avenue in the treatment of insulin resistance. Metformin-induced activation of AMPK is a key current intervention in the management of type 2 diabetes. However, this treatment does not seem to improve peripheral insulin resistance. In light of this

  12. Different cytokine profile and eosinophil activation are involved in rhinovirus- and RS virus-induced acute exacerbation of childhood wheezing.

    Science.gov (United States)

    Kato, Masahiko; Tsukagoshi, Hiroyuki; Yoshizumi, Masakazu; Saitoh, Mika; Kozawa, Kunihisa; Yamada, Yoshiyuki; Maruyama, Kenichi; Hayashi, Yasuhide; Kimura, Hirokazu

    2011-02-01

    Because little information is available on eosinophil activation and cytokine response in virus-induced wheezing, we attempted to detect respiratory viruses and measure eosinophil cationic protein (ECP), and 27 types of cytokines/chemokines in both serum and nasal secretions from children with wheezing. This study was an observational, case-control investigation of 267 subjects, who were visited and/or hospitalized with acute respiratory symptoms (with wheezing: men, 115; women, 59; mean/median age, 3.6/3.0 years) or who were visited for regular physical examination and treatment (non-symptomatic wheezing: men, 48; women, 31; mean/median, 5.0/4.7 years), and 14 control subjects (controls: men, 9; women, 5; mean/median, 3.6/3.7 years). We detected viruses in nasal secretions from 174 patients with acute exacerbations of wheezing using antigen detection kits or reverse transcription-polymerase chain reaction, followed by direct DNA sequencing analysis. We measured peripheral eosinophil counts, and serum concentrations of ECP and 27 cytokines/chemokines using a multiplex bead-based assay in patients with wheezing or non-symptomatic wheezing. We also examined nasal ECP and 27 cytokines/chemokines in patients with wheezing. Of 174 samples from wheezing exacerbations, rhinovirus was detected in 59; respiratory syncytial (RS) virus in 44; enterovirus in 17; other viruses in 19; and no viruses in 35. Serum concentrations of ECP, IL-5, IL-6, IL-1ra, and IP-10 were significantly elevated in rhinovirus-induced wheezing compared with non-symptomatic wheezing. Similarly, serum ECP, IL-5, and IP-10 were significantly higher in rhinovirus-induced wheezing than in controls. On the other hand, IL-1ra and IP-10, but not ECP and IL-5 were significantly higher in RS virus-induced wheezing than in controls. Furthermore, only IL-5 was significantly elevated in the rhinovirus group compared with the RS virus group in both serum and nasal secretions. Different cytokine profile and

  13. Mitochondrial Ca2+-dependent NLRP3 activation exacerbates the Pseudomonas aeruginosa-driven inflammatory response in cystic fibrosis.

    Science.gov (United States)

    Rimessi, Alessandro; Bezzerri, Valentino; Patergnani, Simone; Marchi, Saverio; Cabrini, Giulio; Pinton, Paolo

    2015-02-04

    The common pathological manifestation of cystic fibrosis (CF) is associated with an excessive lung inflammatory response characterized by interleukin-1β accumulation. CF airway epithelial cells show an exacerbated pro-inflammatory response to Pseudomonas aeruginosa; however, it is unclear whether this heightened inflammatory response is intrinsic to cells lacking CF transmembrane conductance regulator (CFTR). Here we demonstrate that the degree and quality of the inflammatory response in CF are supported by P. aeruginosa-dependent mitochondrial perturbation, in which flagellin is the inducer and mitochondrial Ca(2+) uniporter (MCU) is a signal-integrating organelle member for NLRP3 activation and IL-1β and IL-18 processing. Our work elucidates the regulation of the NLRP3 inflammasome by mitochondrial Ca(2+) in the P. aeruginosa-dependent inflammatory response and deepens our understanding of the significance of mitochondria in the Ca(2+)-dependent control of inflammation.

  14. Role of diacylglycerol activation of PKCθ in lipid-induced muscle insulin resistance in humans

    Science.gov (United States)

    Szendroedi, Julia; Yoshimura, Toru; Phielix, Esther; Koliaki, Chrysi; Marcucci, Mellissa; Zhang, Dongyan; Jelenik, Tomas; Müller, Janette; Herder, Christian; Nowotny, Peter; Shulman, Gerald I.; Roden, Michael

    2014-01-01

    Muscle insulin resistance is a key feature of obesity and type 2 diabetes and is strongly associated with increased intramyocellular lipid content and inflammation. However, the cellular and molecular mechanisms responsible for causing muscle insulin resistance in humans are still unclear. To address this question, we performed serial muscle biopsies in healthy, lean subjects before and during a lipid infusion to induce acute muscle insulin resistance and assessed lipid and inflammatory parameters that have been previously implicated in causing muscle insulin resistance. We found that acute induction of muscle insulin resistance was associated with a transient increase in total and cytosolic diacylglycerol (DAG) content that was temporally associated with protein kinase (PKC)θ activation, increased insulin receptor substrate (IRS)-1 serine 1101 phosphorylation, and inhibition of insulin-stimulated IRS-1 tyrosine phosphorylation and AKT2 phosphorylation. In contrast, there were no associations between insulin resistance and alterations in muscle ceramide, acylcarnitine content, or adipocytokines (interleukin-6, adiponectin, retinol-binding protein 4) or soluble intercellular adhesion molecule-1. Similar associations between muscle DAG content, PKCθ activation, and muscle insulin resistance were observed in healthy insulin-resistant obese subjects and obese type 2 diabetic subjects. Taken together, these data support a key role for DAG activation of PKCθ in the pathogenesis of lipid-induced muscle insulin resistance in obese and type 2 diabetic individuals. PMID:24979806

  15. Possible activation of auto-immune thyroiditis from continuous subcutaneous infusion of genapol-containing insulin.

    Science.gov (United States)

    Chantelau, E

    2000-09-01

    A case of a type 1 diabetic woman with auto-immune thyroiditis is reported, in whom repeated exposure to insulin containing Genapol(R) (polyethylen-polypropylenglycol) over 3 years reproducibly parallels with an increase of serum TSH (thyroid-stimulating hormone) above the normal limit. Previously, adverse effects of Genapol(R) insulin have been related to its intraperitoneal application, and thought to be restricted to anti-insulin-immunity; activating effects on thyroid auto-immunity have been repeatedly disputed. We suggest that Genapol(R) insulin should be replaced by other insulin preparations with a better safety record.

  16. Insulin

    Science.gov (United States)

    ... your diabetes medicines. Be active and get exercise. Dance, take a walk, or join an exercise class. Check with your doctor about safe ways to be more active. Monitor your overall mental and physical health. Work with your health care team to keep ...

  17. Cysteine 904 is required for maximal insulin degrading enzyme activity and polyanion activation.

    Directory of Open Access Journals (Sweden)

    Eun Suk Song

    Full Text Available Cysteine residues in insulin degrading enzyme have been reported as non-critical for its activity. We found that converting the twelve cysteine residues in rat insulin degrading enzyme (IDE to serines resulted in a cysteine-free form of the enzyme with reduced activity and decreased activation by polyanions. Mutation of each cysteine residue individually revealed cysteine 904 as the key residue required for maximal activity and polyanion activation, although other cysteines affect polyanion binding to a lesser extent. Based on the structure of IDE, Asn 575 was identified as a potential hydrogen bond partner for Cys904 and mutation of this residue also reduced activity and decreased polyanion activation. The oligomerization state of IDE did not correlate with its activity, with the dimer being the predominant form in all the samples examined. These data suggest that there are several conformational states of the dimer that affect activity and polyanion activation.

  18. Insulin analogues display atypical differentiative activities in skin keratinocytes.

    Science.gov (United States)

    Solomon Zemler, Ravid; Weingarten, Galina; Sarfstein, Rive; Laron, Zvi; Werner, Haim; Wertheimer, Efrat

    2015-02-01

    We have previously shown that both insulin and IGF1 lead to increased proliferation of keratinocytes. However, whereas insulin supports keratinocytes differentiation, IGF1 inhibits this process. The aim of the present study was to examine the proliferative and differentiative effects of insulin analogues (glargine, detemir, lispro and aspart) in primary keratinocytes in comparison with insulin and IGF1. Primary keratinocytes cultures were produced from newborn BALB/c mice skin. Proliferation rates were assessed by [(3)H]-thymidine incorporation and XTT assays and differentiation was evaluated by Western blots analysis. Insulin receptor and IGF1 receptor phosphorylation was assessed by immunoprecipitation assays. Treatment with glargine or detemir resulted in an insulin-like effect on the differentiation process whereas lispro and aspart treatment led to an IGF1-like effect. In addition, treatment of keratinocytes with aspart led to a rapid phosphorylation of the IGF1 receptor. Our study provides evidence that insulin analogues elicit atypical actions in the skin.

  19. A two-week reduction of ambulatory activity attenuates peripheral insulin sensitivity

    DEFF Research Database (Denmark)

    Krogh-Madsen, Rikke; Thyfault, John P; Broholm, Christa

    2009-01-01

    activity would influence peripheral insulin sensitivity. We aimed to explore if healthy, non-exercising subjects who went from a normal to a low level of ambulatory activity for two weeks would display metabolic alterations including reduced peripheral insulin sensitivity. -To do this, ten healthy young...... possible biological cause for the public health problem of type 2 diabetes has been identified. Reduced ambulatory activity for two weeks in healthy, non-exercising young men significantly reduced peripheral insulin sensitivity, cardiovascular fitness, and lean leg mass. Key words: Inactivity, Insulin...

  20. Primary defects in beta-cell function further exacerbated by worsening of insulin resistance mark the development of impaired glucose tolerance in obese adolescents.

    Science.gov (United States)

    Cali, Anna M G; Man, Chiara Dalla; Cobelli, Claudio; Dziura, James; Seyal, Aisha; Shaw, Melissa; Allen, Karin; Chen, Shu; Caprio, Sonia

    2009-03-01

    Impaired glucose tolerance (IGT) is a pre-diabetic state of increasing prevalence among obese adolescents. The purpose of this study was to determine the natural history of progression from normal glucose tolerance (NGT) to IGT in obese adolescents. We determined the evolution of beta-cell function, insulin sensitivity (S(I)), and glucose tolerance in a multiethnic group of 60 obese adolescents over the course of approximately 30 months. Each subject underwent three serial 3-h oral glucose tolerance tests. Dynamic, static, and total beta-cell responsivity (Phi(d), Phi(s), and Phi(tot), respectively) and S(i) were assessed by oral C-peptide and glucose minimal models. The disposition index (DI), which adjusts insulin secretion for S(i), was calculated. At baseline, all 60 subjects had NGT. Seventy-seven percent (46 subjects) maintained NGT over the three testing periods (nonprogressors), whereas 23% (14 subjects) developed IGT over time (progressors). At baseline, percent fat and BMI Z score were comparable between the groups. Fasting plasma glucose, 2-h glucose, glucose area under the curve at 180 min, and Phi(d) were significantly different between the two groups at baseline, whereas S(i) was comparable between the two groups. Over time, although S(i) remained unchanged in nonprogressors, it steadily worsened by approximately 45% (P > 0.04) in progressors. beta-Cell responsivity decreased by 20% in progressors, whereas it remained stable in nonprogressors. The DI showed a progressive decline in progressors compared with a modest improvement in nonprogressors (P = 0.02). Obese adolescents who progress to IGT may manifest primary defects in beta-cell function. In addition, progressive decline in S(i) further aggravates beta-cell function, contributing to the worsening of glucose intolerance.

  1. Primary Defects in β-Cell Function Further Exacerbated by Worsening of Insulin Resistance Mark the Development of Impaired Glucose Tolerance in Obese Adolescents

    Science.gov (United States)

    Cali, Anna M.G.; Man, Chiara Dalla; Cobelli, Claudio; Dziura, James; Seyal, Aisha; Shaw, Melissa; Allen, Karin; Chen, Shu; Caprio, Sonia

    2009-01-01

    OBJECTIVE—Impaired glucose tolerance (IGT) is a pre-diabetic state of increasing prevalence among obese adolescents. The purpose of this study was to determine the natural history of progression from normal glucose tolerance (NGT) to IGT in obese adolescents. RESEARCH DESIGN AND METHODS—We determined the evolution of β-cell function, insulin sensitivity (SI), and glucose tolerance in a multiethnic group of 60 obese adolescents over the course of approximately 30 months. Each subject underwent three serial 3-h oral glucose tolerance tests. Dynamic, static, and total β-cell responsivity (Φd, Φs, and Φtot, respectively) and Si were assessed by oral C-peptide and glucose minimal models. The disposition index (DI), which adjusts insulin secretion for Si, was calculated. RESULTS—At baseline, all 60 subjects had NGT. Seventy-seven percent (46 subjects) maintained NGT over the three testing periods (nonprogressors), whereas 23% (14 subjects) developed IGT over time (progressors). At baseline, percent fat and BMI Z score were comparable between the groups. Fasting plasma glucose, 2-h glucose, glucose area under the curve at 180 min, and Φd were significantly different between the two groups at baseline, whereas Si was comparable between the two groups. Over time, although Si remained unchanged in nonprogressors, it steadily worsened by ∼45% (P > 0.04) in progressors. β-Cell responsivity decreased by 20% in progressors, whereas it remained stable in nonprogressors. The DI showed a progressive decline in progressors compared with a modest improvement in nonprogressors (P = 0.02). CONCLUSIONS—Obese adolescents who progress to IGT may manifest primary defects in β-cell function. In addition, progressive decline in Si further aggravates β-cell function, contributing to the worsening of glucose intolerance. PMID:19106382

  2. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin.

    Science.gov (United States)

    Hjorth, Christian Fogt; Norrman, Mathias; Wahlund, Per-Olof; Benie, Andrew J; Petersen, Bent O; Jessen, Christian M; Pedersen, Thomas Å; Vestergaard, Kirsten; Steensgaard, Dorte B; Pedersen, Jan Skov; Naver, Helle; Hubálek, František; Poulsen, Christian; Otzen, Daniel

    2016-04-01

    A specific covalently linked dimeric species of insulin high molecular weight products (HMWPs), formed during prolonged incubation of a neutral pharmaceutical formulation of human insulin, were characterized in terms of tertiary structure, self-association, biological activity, and fibrillation properties. The dimer was formed by a covalent link between A21Asn and B29Lys. It was analyzed using static and dynamic light scattering and small-angle X-ray scattering to evaluate its self-association behavior. The tertiary structure was obtained using nuclear magnetic resonance and X-ray crystallography. The biological activity of HMWP was determined using 2 in vitro assays, and its influence on fibrillation was investigated using Thioflavin T assays. The dimer's tertiary structure was nearly identical to that of the noncovalent insulin dimer, and it was able to form hexamers in the presence of zinc. The dimer exhibited reduced propensity for self-association in the absence of zinc but significantly postponed the onset of fibrillation in insulin formulations. Consistent with its dimeric state, the tested species of HMWP showed little to no biological activity in the used assays. This study is the first detailed characterization of a specific type of human insulin HMWP formed during storage of a marketed pharmaceutical formulation. These results indicate that this specific type of HMWP is unlikely to antagonize the physical stability of the formulation, as HMWP retained a tertiary structure similar to the noncovalent dimer and participated in hexamer assembly in the presence of zinc. In addition, increasing amounts of HMWP reduce the rate of insulin fibrillation.

  3. Intraoral film containing insulin-phospholipid microemulsion: formulation and in vivo hypoglycemic activity study.

    Science.gov (United States)

    Rachmawati, Heni; Haryadi, Bernard Manuel; Anggadiredja, Kusnandar; Suendo, Veinardi

    2015-06-01

    Non-invasive administration of insulin is expected for better diabetes mellitus therapy. In this report, we developed intraoral preparation for insulin. Insulin was encapsulated into nanocarrier using self-assembly emulsification process. To increase lipophilicity of insulin, it was dispersed in phospholipid resulted in insulin-phospholipid solid dispersion. The microemulsion formula was established from our previous work which contained glyceryl monooleate (GMO), Tween 20, and polyethylene glycol (PEG 400) in a ratio of 1:8:1. To confirm the formation of insulin-phospholipid solid dispersion, PXRD, FTIR spectroscopy, and Raman spectroscopy were performed. Then, the microemulsion was evaluated for droplet size and distribution, zeta potential, entrapment efficiency, physical stability, and Raman spectroscopy. In addition, microemulsion with expected characteristic was evaluated for in vitro release, in vitro permeation, and in vivo activity. The droplets size of ∼100 nm with narrow distribution and positive charge of +0.56 mV were formed. The insulin encapsulated in the oil droplet was accounted of >90%. Water-soluble chitosan seems to be a promising film matrix polymer which also functioned as insulin release controller. Oral administration of insulin microemulsion to healthy Swiss-Webster mice showed hypoglycemic effect indicating the success of this protein against a harsh environment of the gastrointestinal tract. This effectiveness significantly increased by fourfold as compared to free insulin. Taken together, microemulsion seems to be a promising carrier for oral delivery of insulin.

  4. Inhibition of endocytosis exacerbates TNF-α-induced endothelial dysfunction via enhanced JNK and p38 activation.

    Science.gov (United States)

    Choi, Hyehun; Nguyen, Hong N; Lamb, Fred S

    2014-04-15

    Tumor necrosis factor-α (TNF-α) is a pro-inflammatory cytokine that causes endothelial dysfunction. Endocytosis of TNF-α receptors (TNFR) precedes endosomal reactive oxygen species (ROS) production, which is required for NF-κB activation in vascular smooth muscle cells. It is unknown how endocytosis of TNFRs impacts signaling in endothelial cells. We hypothesized that TNF-α-induced endothelial dysfunction is induced by both endosomal and cell surface events, including NF-κB and mitogen-activated protein kinases (MAPKs) activation, and endocytosis of the TNFR modifies signaling. Mesenteric artery segments from C57BL/6 mice were treated with TNF-α (10 ng/ml) for 22 h in tissue culture, with or without signaling inhibitors (dynasore for endocytosis, SP600125 for JNK, SB203580 for p38, U0126 for ERK), and vascular function was assessed. Endothelium-dependent relaxation to acetylcholine (ACh) was impaired by TNF-α, and dynasore exacerbated this, whereas JNK or p38 inhibition prevented these effects. In cultured endothelial cells from murine mesenteric arteries, dynasore potentiated JNK and p38 but not ERK phosphorylation and promoted cell death. NF-κB activation by TNF-α was decreased by dynasore. JNK inhibition dramatically increased both the magnitude and duration of TNF-α-induced NF-κB activation and potentiated intercellular adhesion molecule-1 (ICAM-1) activation. Dynasore still inhibited NF-κB activation in the presence of SP600125. Thus TNF-α-induced endothelial dysfunction is both JNK and p38 dependent. Endocytosis modulates the balance of NF-κB and MAPK signaling, and inhibition of NF-κB activation by JNK limits this pro-proliferative signal, which may contribute to endothelial cell death in response to TNF-α.

  5. Growth hormone-induced insulin resistance in human subjects involves reduced pyruvate dehydrogenase activity

    DEFF Research Database (Denmark)

    Nellemann, Birgitte; Vendelbo, Mikkel H; Nielsen, Thomas S

    2014-01-01

    Insulin resistance induced by growth hormone (GH) is linked to promotion of lipolysis by unknown mechanisms. We hypothesized that suppression of the activity of pyruvate dehydrogenase in the active form (PDHa) underlies GH-induced insulin resistance similar to what is observed during fasting....

  6. Bcl10 links saturated fat overnutrition with hepatocellular NF-kB activation and insulin resistance

    NARCIS (Netherlands)

    Beek, M.H. van; Oravecz-Wilson, K.I.; Delekta, P.C.; Gu, S.; Li, X.; Jin, X.; Apel, I.J.; Konkle, K.S.; Feng, Y.; Teitelbaum, D.H.; Ruland, J.; McAllister-Lucas, L.M.; Lucas, P.C.

    2012-01-01

    Excess serum free fatty acids (FFAs) are fundamental to the pathogenesis of insulin resistance. With high-fat feeding, FFAs activate NF-kB in target tissues, initiating negative crosstalk with insulin signaling. However, the mechanisms underlying FFA-dependent NF-kB activation remain unclear. Here,

  7. Body fat related to daily physical activity and insulin concentrations in non-diabetic children

    DEFF Research Database (Denmark)

    Dencker, Magnus; Thorsson, Ola; Karlsson, Magnus K

    2007-01-01

    This study explored the associations between body fat versus daily physical activity and insulin concentrations in non-diabetic young children in a cross-sectional study of 172 children (93 boys and 79 girls) aged 8-11 years. Blood samples were analysed for serum insulin and daily physical activity...

  8. Dark chocolate exacerbates acne.

    Science.gov (United States)

    Vongraviopap, Saivaree; Asawanonda, Pravit

    2016-05-01

    The effects of chocolate on acne exacerbations have recently been reevaluated. For so many years, it was thought that it had no role in worsening acne. To investigate whether 99% dark chocolate, when consumed in regular daily amounts, would cause acne to worsen in acne-prone male subjects, twenty-five acne prone male subjects were asked to consume 25 g of 99% dark chocolate daily for 4 weeks. Assessments which included Leeds revised acne scores as well as lesion counts took place weekly. Food frequency questionnaire was used, and daily activities were recorded. Statistically significant changes of acne scores and numbers of comedones and inflammatory papules were detected as early as 2 weeks into the study. At 4 weeks, the changes remained statistically significant compared to baseline. Dark chocolate when consumed in normal amounts for 4 weeks can exacerbate acne in male subjects with acne-prone skin. © 2015 The International Society of Dermatology.

  9. Ghrelin counteracts insulin-induced activation of vagal afferent neurons via growth hormone secretagogue receptor.

    Science.gov (United States)

    Iwasaki, Yusaku; Dezaki, Katsuya; Kumari, Parmila; Kakei, Masafumi; Yada, Toshihiko

    2015-08-01

    Vagal afferent nerves sense meal-related gastrointestinal and pancreatic hormones and convey their information to the brain, thereby regulating brain functions including feeding. We have recently demonstrated that postprandial insulin directly acts on the vagal afferent neurons. Plasma concentrations of orexigenic ghrelin and anorexigenic insulin show reciprocal dynamics before and after meals. The present study examined interactive effects of ghrelin and insulin on vagal afferent nerves. Cytosolic Ca(2+) concentration ([Ca(2+)]i) in isolated nodose ganglion (NG) neurons was measured to monitor their activity. Insulin at 10(-7)M increased [Ca(2+)]i in NG neurons, and the insulin-induced [Ca(2+)]i increase was inhibited by treatment with ghrelin at 10(-8)M. This inhibitory effect of ghrelin was attenuated by [D-Lys(3)]-GHRP-6, an antagonist of growth hormone-secretagogue receptor (GHSR). Des-acyl ghrelin had little effect on insulin-induced [Ca(2+)]i increases in NG neurons. Ghrelin did not affect [Ca(2+)]i increases in response to cholecystokinin (CCK), a hormone that inhibits feeding via vagal afferent neurons, indicating that ghrelin selectively counteracts the insulin action. These results demonstrate that ghrelin via GHSR suppresses insulin-induced activation of NG neurons. The action of ghrelin to counteract insulin effects on NG might serve to efficiently inform the brain of the systemic change between fasting-associated ghrelin-dominant and fed-associated insulin-dominant states for the homeostatic central regulation of feeding and metabolism.

  10. Interleukin 16 and CCL17/thymus and activation-regulated chemokine in patients with aspirin-exacerbated respiratory disease.

    Science.gov (United States)

    Teran, Luis Manuel; Ramirez-Jimenez, Fernando; Soid-Raggi, Gabriela; Velazquez, Juan Raymundo

    2017-02-01

    Interleukin (IL) 16 and thymus and activation-regulated cytokine (TARC) are chemoattractant cytokines for eosinophils and TH2 cells. Differential levels of these components in aspirin-exacerbated respiratory disease (AERD) and allergic rhinitis with asthma (ARwA) may be related to a different inflammatory response in both asthma phenotypes. To assess the nasal lavage immunoreactivity of IL-16 and TARC cytokines. We used multienzyme-linked immunosorbent assays to detect IL-5, IL-13, IL-16, IL-33, I-309/CCL1, TARC/CCL17, monocyte-derived chemokine/CCL22, periostin, and eosinophil cationic protein levels in nasal lavages from patients with AERD and patients with ARwA. The IL-13, IL-16, TARC, and periostin levels were significantly higher in patients with AERD compared with those of patients with ARwA. Correlation analysis of mediator levels in AERD revealed a possible role of IL-16 and TARC in eosinophil recruitment and activation. IL-16, TARC, and periostin distinguish between patients with AERD and those with ARwA. These mediators, taken together rather than individually, may comprise good specific nasal markers in patients with AERD. The effects of IL-16 and TARC on TH1, TH2, and T-regulatory cell functions in AERD cannot be disregarded. Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  11. Kv1.1 knock-in ataxic mice exhibit spontaneous myokymic activity exacerbated by fatigue, ischemia and low temperature

    Science.gov (United States)

    Brunetti, Orazio; Imbrici, Paola; Botti, Fabio Massimo; Pettorossi, Vito Enrico; D'Adamo, Maria Cristina; Valentino, Mario; Zammit, Christian; Mora, Marina; Gibertini, Sara; Di Giovanni, Giuseppe; Muscat, Richard; Pessia, Mauro

    2012-01-01

    Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder characterized by myokymia and attacks of ataxic gait often precipitated by stress. Several genetic mutations have been identified in the Shaker-like K+ channel Kv1.1 (KCNA1) of EA1 individuals, including V408A, which result in remarkable channel dysfunction. By inserting the heterozygous V408A, mutation in one Kv1.1 allele, a mouse model of EA1 has been generated (Kv1.1V408A/+). Here, we investigated the neuromuscular transmission of Kv1.1V408A/+ ataxic mice and their susceptibility to physiologically relevant stressors. By using in vivo preparations of lateral gastrocnemius (LG) nerve–muscle from Kv1.1+/+ and Kv1.1V408A/+ mice, we show that the mutant animals exhibit spontaneous myokymic discharges consisting of repeated singlets, duplets or multiplets, despite motor nerve axotomy. Two-photon laser scanning microscopy from the motor nerve, ex vivo, revealed spontaneous Ca2 + signals that occurred abnormally only in preparations dissected from Kv1.1V408A/+ mice. Spontaneous bursting activity, as well as that evoked by sciatic nerve stimulation, was exacerbated by muscle fatigue, ischemia and low temperatures. These stressors also increased the amplitude of compound muscle action potential. Such abnormal neuromuscular transmission did not alter fiber type composition, neuromuscular junction and vascularization of LG muscle, analyzed by light and electron microscopy. Taken together these findings provide direct evidence that identifies the motor nerve as an important generator of myokymic activity, that dysfunction of Kv1.1 channels alters Ca2 + homeostasis in motor axons, and also strongly suggest that muscle fatigue contributes more than PNS fatigue to exacerbate the myokymia/neuromyotonia phenotype. More broadly, this study points out that juxtaparanodal K+ channels composed of Kv1.1 subunits exert an important role in dampening the excitability of motor nerve axons during fatigue or

  12. Activity of histidine in peripheral blood erythrocytes of pregnant women during exacerbation of cytomegalovirus infection.

    Science.gov (United States)

    Lutsenko, M T; Andrievskaya, I A

    2014-10-01

    We studied the effect of active cytomegalovirus infection on histidine content in peripheral blood erythrocytes of pregnant women at gestation weeks 20-22 and its involvement into hemoglobin oxygenation. Using the histochemical technique developed by us, we studied the distribution of products of specific reaction for histidine in peripheral blood erythrocytes of pregnant women. The percentage of histidine-positive erythrocytes and their area were evaluated. The relationship between the distribution of the products of the reaction for histidine in peripheral blood erythrocytes of pregnant women and the titer of anti-cytomegalovirus IgG was revealed. The histidine content in peripheral blood erythrocytes of pregnant women with active cytomegalovirus infection was reduced, which impaired heme binding to globin and decreased the formation of oxyhemoglobin.

  13. Targeted activation of endothelin-1 exacerbates hypoxia-induced pulmonary hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Satwiko, Muhammad Gahan [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Ikeda, Koji [Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan); Nakayama, Kazuhiko [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Yagi, Keiko [Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan); Hocher, Berthold [Institute for Nutritional Science, University of Potsdam, Potsdam (Germany); Hirata, Ken-ichi [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Emoto, Noriaki, E-mail: emoto@med.kobe-u.ac.jp [Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe (Japan); Department of Clinical Pharmacy, Kobe Pharmaceutical University, Kobe (Japan)

    2015-09-25

    Pulmonary arterial hypertension (PAH) is a fatal disease that eventually results in right heart failure and death. Current pharmacologic therapies for PAH are limited, and there are no drugs that could completely cure PAH. Enhanced activity of endothelin system has been implicated in PAH severity and endothelin receptor antagonists have been used clinically to treat PAH. However, there is limited experimental evidence on the direct role of enhanced endothelin system activity in PAH. Here, we investigated the correlation between endothelin-1 (ET-1) and PAH using ET-1 transgenic (ETTG) mice. Exposure to chronic hypoxia increased right ventricular pressure and pulmonary arterial wall thickness in ETTG mice compared to those in wild type mice. Of note, ETTG mice exhibited modest but significant increase in right ventricular pressure and vessel wall thickness relative to wild type mice even under normoxic conditions. To induce severe PAH, we administered SU5416, a vascular endothelial growth factor receptor inhibitor, combined with exposure to chronic hypoxia. Treatment with SU5416 modestly aggravated hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial vessel wall thickening in ETTG mice in association with increased interleukin-6 expression in blood vessels. However, there was no sign of obliterative endothelial cell proliferation and plexiform lesion formation in the lungs. These results demonstrated that enhanced endothelin system activity could be a causative factor in the development of PAH and provided rationale for the inhibition of endothelin system to treat PAH. - Highlights: • Role of endothelin-1 in pulmonary arterial hypertension (PAH) was investigated. • The endothelin-1 transgenic (ETTG) and wild type (WT) mice were analyzed. • ETTG mice spontaneously developed PAH under normoxia conditions. • SU5416 further aggravated PAH in ETTG mice. • Enhanced endothelin system activity could be a causative factor in

  14. Exacerbation of Bloody Diarrhea as a Side Effect of Mesalamine Treatment of Active Ulcerative Colitis

    OpenAIRE

    Yuichi Shimodate; Kunihiro Takanashi; Eriko Waga; Tomoki Fujita; Shinichi Katsuki; Masafumi Nomura

    2011-01-01

    Mesalamine has been used as the first-line therapy for the treatment of ulcerative colitis (UC) because of its efficacy and fewer side effects. However, earlier study showed that mesalamine occasionally causes diarrhea. We are presenting a patient with active UC in whom bloody diarrhea accompanied by abdominal pain and fever occurred and the symptoms were aggravated after administration of mesalamine. In order to clarify the reason of symptoms aggravation, drug lymphocyte stimulation test and...

  15. Amoxicillin concentrations in relation to beta-lactamase activity in sputum during exacerbations of chronic obstructive pulmonary disease

    NARCIS (Netherlands)

    Brusse-Keizer, Marjolein; VanderValk, Paul; van der Zanden, Rogier W.; Nijdam, Lars; van der Palen, Job; Hendrix, Ron; Movig, Kris

    2015-01-01

    Background: Acute exacerbations of chronic obstructive pulmonary disease (COPD) are often treated with antibiotics. Theoretically, to be maximally effective, the antibiotic concentration at sites of infection should exceed the minimum inhibitory concentration at which 90% of the growth of potential

  16. A physiological increase in insulin suppresses gluconeogenic gene activation in fetal sheep with sustained hypoglycemia.

    Science.gov (United States)

    Thorn, Stephanie R; Sekar, Satya M; Lavezzi, Jinny R; O'Meara, Meghan C; Brown, Laura D; Hay, William W; Rozance, Paul J

    2012-10-15

    Reduced maternal glucose supply to the fetus and resulting fetal hypoglycemia and hypoinsulinemia activate fetal glucose production as a means to maintain cellular glucose uptake. However, this early activation of fetal glucose production may be accompanied by hepatic insulin resistance. We tested the capacity of a physiological increase in insulin to suppress fetal hepatic gluconeogenic gene activation following sustained hypoglycemia to determine whether hepatic insulin sensitivity is maintained. Control fetuses (CON), hypoglycemic fetuses induced by maternal insulin infusion for 8 wk (HG), and 8 wk HG fetuses that received an isoglycemic insulin infusion for the final 7 days (HG+INS) were studied. Glucose and insulin concentrations were 60% lower in HG compared with CON fetuses. Insulin was 50% higher in HG+INS compared with CON and four-fold higher compared with HG fetuses. Expression of the hepatic gluconeogenic genes, PCK1, G6PC, FBP1, GLUT2, and PGC1A was increased in the HG and reduced in the HG+INS liver. Expression of the insulin-regulated glycolytic and lipogenic genes, PFKL and FAS, was increased in the HG+INS liver. Total FOXO1 protein expression, a gluconeogenic activator, was 60% higher in the HG liver. Despite low glucose, insulin, and IGF1 concentrations, phosphorylation of AKT and ERK was higher in the HG liver. Thus, a physiological increase in fetal insulin is sufficient for suppression of gluconeogenic genes and activation of glycolytic and lipogenic genes in the HG fetal liver. These results demonstrate that fetuses exposed to sustained hypoglycemia have maintained hepatic insulin action in contrast to fetuses exposed to placental insufficiency.

  17. Structure, antihyperglycemic activity and cellular actions of a novel diglycated human insulin

    DEFF Research Database (Denmark)

    O'Harte, F P; Boyd, A C; McKillop, A M;

    2000-01-01

    Human insulin was glycated under hyperglycemic reducing conditions and a novel diglycated form (M(r) 6135.1 Da) was purified by RP-HPLC. Endoproteinase Glu-C digestion combined with mass spectrometry and automated Edman degradation localized glycation to Gly(1) and Phe(1) of the insulin A- and B......-chains, respectively. Intraperitoneal (i.p.) administration of diglycated insulin to mice alone or in combination with glucose (7 nmol/kg) resulted in a 43-61% and 11-34% reduction in glucose lowering activity, respectively, compared with native insulin. Consistent with these findings, diglycated insulin (10(-9) to 10......(-7) mol/liter) was 22-38% less effective (P insulin in stimulating glucose uptake, glucose oxidation and glycogen production in isolated mouse abdominal muscle....

  18. Elevation of serum insulin concentration during euglycemic hyperinsulinemic clamp studies leads to similar activation of insulin receptor kinase in skeletal muscle of subjects with and without NIDDM

    DEFF Research Database (Denmark)

    Klein, H H; Vestergaard, H; Kotzke, G;

    1995-01-01

    The role of skeletal muscle insulin receptor kinase in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) was investigated. Muscle biopsies from 13 patients with NIDDM and 10 control subjects at fasting serum insulin concentrations and approximately 1,000 pmol/l steady-state serum...... insulin during euglycemic hyperinsulinemic clamps were immediately frozen. The biopsies were then solubilized, and the receptors were immobilized to anti-insulin receptor antibody-coated microwells. Receptor kinase and binding activities were consecutively measured in these wells. The increase in serum...... insulin concentration (73 +/- 14 to 1,004 +/- 83 and 45 +/- 7 to 1,07 +/- 77 pmol/l in the NIDDM and control groups, respectively) had similar effects on receptor kinase activity in both study groups (12 +/- 1 to 42 +/- 5 and 12 +/- 2 to 47 +/- 5 amol P.fmol binding activity-1. min-1 in the NIDDM...

  19. Chronic stress enhances microglia activation and exacerbates death of nigral dopaminergic neurons under conditions of inflammation.

    Science.gov (United States)

    de Pablos, Rocío M; Herrera, Antonio J; Espinosa-Oliva, Ana M; Sarmiento, Manuel; Muñoz, Mario F; Machado, Alberto; Venero, José L

    2014-02-24

    Parkinson's disease is an irreversible neurodegenerative disease linked to progressive movement disorders and is accompanied by an inflammatory reaction that is believed to contribute to its pathogenesis. Since sensitivity to inflammation is not the same in all brain structures, the aim of this work was to test whether physiological conditions as stress could enhance susceptibility to inflammation in the substantia nigra, where death of dopaminergic neurons takes place in Parkinson's disease. To achieve our aim, we induced an inflammatory process in nonstressed and stressed rats (subject to a chronic variate stress) by a single intranigral injection of lipopolysaccharide, a potent proinflammogen. The effect of this treatment was evaluated on inflammatory markers as well as on neuronal and glial populations. Data showed a synergistic effect between inflammation and stress, thus resulting in higher microglial activation and expression of proinflammatory markers. More important, the higher inflammatory response seen in stressed animals was associated with a higher rate of death of dopaminergic neurons in the substantia nigra, the most characteristic feature seen in Parkinson's disease. This effect was dependent on glucocorticoids. Our data demonstrate that stress sensitises midbrain microglia to further inflammatory stimulus. This suggests that stress may be an important risk factor in the degenerative processes and symptoms of Parkinson's disease.

  20. Circulating insulin stimulates fatty acid retention in white adipose tissue via KATP channel activation in the central nervous system only in insulin-sensitive mice.

    Science.gov (United States)

    Coomans, Claudia P; Geerling, Janine J; Guigas, Bruno; van den Hoek, Anita M; Parlevliet, Edwin T; Ouwens, D Margriet; Pijl, Hanno; Voshol, Peter J; Rensen, Patrick C N; Havekes, Louis M; Romijn, Johannes A

    2011-09-01

    Insulin signaling in the central nervous system (CNS) is required for the inhibitory effect of insulin on glucose production. Our aim was to determine whether the CNS is also involved in the stimulatory effect of circulating insulin on the tissue-specific retention of fatty acid (FA) from plasma. In wild-type mice, hyperinsulinemic-euglycemic clamp conditions stimulated the retention of both plasma triglyceride-derived FA and plasma albumin-bound FA in the various white adipose tissues (WAT) but not in other tissues, including brown adipose tissue (BAT). Intracerebroventricular (ICV) administration of insulin induced a similar pattern of tissue-specific FA partitioning. This effect of ICV insulin administration was not associated with activation of the insulin signaling pathway in adipose tissue. ICV administration of tolbutamide, a K(ATP) channel blocker, considerably reduced (during hyperinsulinemic-euglycemic clamp conditions) and even completely blocked (during ICV administration of insulin) WAT-specific retention of FA from plasma. This central effect of insulin was absent in CD36-deficient mice, indicating that CD36 is the predominant FA transporter in insulin-stimulated FA retention by WAT. In diet-induced insulin-resistant mice, these stimulating effects of insulin (circulating or ICV administered) on FA retention in WAT were lost. In conclusion, in insulin-sensitive mice, circulating insulin stimulates tissue-specific partitioning of plasma-derived FA in WAT in part through activation of K(ATP) channels in the CNS. Apparently, circulating insulin stimulates fatty acid uptake in WAT but not in BAT, directly and indirectly through the CNS.

  1. Insulin resistance in Alzheimer's disease (AD) mouse intestinal macrophages is mediated by activation of JNK.

    Science.gov (United States)

    Zhou, Y-L; Du, Y-F; Du, H; Shao, P

    2017-04-01

    Alzheimer's disease (AD) has been considered as a metabolic disorder disease, which closely related to insulin signaling impairment. Therefore, identifying the potential mechanism of insulin resistance is important for AD treatment. An APP/PS1 double transgenic AD mouse model was introduced to study insulin resistance in gut. The expressions of AD markers and key elements of insulin signaling were detected in ileum and intestinal macrophages of AD mice by immunohistochemistry. Furthermore, mouse intestinal macrophage cell line RAW264.7 was treated by Aβ25-35 or Aβ25-35 + insulin to explore the mechanism of insulin resistance in vitro. The expression of IR-β and the activation of cell signaling related proteins (Insulin receptor substrate 1 (IRS1), protein kinase B (AKT) and c-Jun N-terminal kinase (JNK)) in Aβ25-35-stimulated macrophages were performed via Western blotting. The expressions of IRS1, Aβ and Tuj in AD mice ileum were significantly different from WT mice (pinsulin could reverse these changes (pinsulin addition. Activation of JNK pathway played an important role in insulin resistance of AD mice, suggesting that inhibition of JNK pathway might be a new strategy toward resolving insulin resistance related diseases, such as AD.

  2. Dietary fiber stabilizes blood glucose and insulin levels and reduces physical activity in sows (Sus scrofa)

    NARCIS (Netherlands)

    Leeuw, de J.A.; Jongbloed, A.W.; Verstegen, M.W.A.

    2004-01-01

    The aim of this study was to test whether a diet with a high level of fermentable dietary fiber can stabilize interprandial blood glucose and insulin levels, prevent declines below basal levels, and reduce physical activity in limited-fed breeding sows. Stable levels of glucose and insulin may preve

  3. Dietary fiber stabilizes blood glucose and insulin levels and reduces physical activity in sows (Sus scrofa)

    NARCIS (Netherlands)

    Leeuw, de J.A.; Jongbloed, A.W.; Verstegen, M.W.A.

    2004-01-01

    The aim of this study was to test whether a diet with a high level of fermentable dietary fiber can stabilize interprandial blood glucose and insulin levels, prevent declines below basal levels, and reduce physical activity in limited-fed breeding sows. Stable levels of glucose and insulin may preve

  4. Role of AMP-activated protein kinase for regulating post-exercise insulin sensitivity

    DEFF Research Database (Denmark)

    Kjøbsted, Rasmus; Wojtaszewski, Jørgen; Treebak, Jonas Thue

    2016-01-01

    Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people that are diagno......Skeletal muscle insulin resistance precedes development of type 2 diabetes (T2D). As skeletal muscle is a major sink for glucose disposal, understanding the molecular mechanisms involved in maintaining insulin sensitivity of this tissue could potentially benefit millions of people...... that are diagnosed with insulin resistance. Regular physical activity in both healthy and insulin-resistant individuals is recognized as the single most effective intervention to increase whole-body insulin sensitivity and thereby positively affect glucose homeostasis. A single bout of exercise has long been known...... to increase glucose disposal in skeletal muscle in response to physiological insulin concentrations. While this effect is identified to be restricted to the previously exercised muscle, the molecular basis for an apparent convergence between exercise- and insulin-induced signaling pathways is incompletely...

  5. Mutational Analysis of the Absolutely Conserved B8Gly: Consequence on Foldability and Activity of Insulin

    Institute of Scientific and Technical Information of China (English)

    Zhan-Yun GUO; Zhou ZHANG; Xiao-Yuan JIA; Yue-Hua TANG; You-Min FENG

    2005-01-01

    B8Gly is absolutely conserved in insulins during evolution. Moreover, its corresponding position is always occupied by a Gly residue in other members of insulin superfamily. Previous work showed that Ala replacement of B8Gly significantly decreased both the activity and the foldability of insulin. However,the effects of substitution are complicated, and different replacements sometimes cause significantly different results. To analyze the effects of B8 replacement by different amino acids, three new insulin/single-chain insulin mutants with B8Gly replaced by Ser, Thr or Leu were prepared by protein engineering, and both their foldability and activity were analyzed. In general, replacement of B8Gly by other amino acids causes significant detriment to the foldability of single-chain insulin: the conformations of the three B8 mutants are essentially different from that of wild-type molecules as revealed by circular dichroism; their disulfide stabilities in redox buffer are significantly decreased; their in vitro refolding efficiencies are decreased approximately two folds; the structural stabilities of the mutants with Ser or Thr substitution are decreased significantly,while Leu substitution has little effect as measured by equilibrium guanidine denaturation. As far as biological activity is concerned, Ser replacement of B8Gly has only a moderate effect: its insulin receptor-binding activity is 23% of native insulin. But Thr or Leu replacement produces significant detriment: the receptorbinding potencies of the two mutants are less than 0.2% of native insulin. The present results suggest that Gly is likely the only applicable natural amino acid for the B8 position of insulin where both foldability and activity are concerned.

  6. A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity

    DEFF Research Database (Denmark)

    Krogh-Madsen, Rikke; Thyfault, John P; Broholm, Christa

    2010-01-01

    if and how low ambulatory activity would influence peripheral insulin sensitivity. We aimed to explore if healthy, nonexercising subjects who went from a normal to a low level of ambulatory activity for 2 wk would display metabolic alterations including reduced peripheral insulin sensitivity. To do this, ten...... possible biological cause for the public health problem of Type 2 diabetes has been identified. Reduced ambulatory activity for 2 wk in healthy, nonexercising young men significantly reduced peripheral insulin sensitivity, cardiovascular fitness, and lean leg mass....

  7. Insulin Excites Anorexigenic Proopiomelanocortin Neurons via Activation of Canonical Transient Receptor Potential Channels

    Science.gov (United States)

    Qiu, Jian; Zhang, Chunguang; Borgquist, Amanda; Nestor, Casey C; Smith, Arik W.; Bosch, Martha A.; Ku, Stephen; Wagner, Edward J.; Rønnekleiv, Oline K.; Kelly, Martin J.

    2014-01-01

    SUMMARY Proopiomelanocortin (POMC) neurons within the hypothalamic arcuate nucleus are vital anorexigenic neurons. Although both the leptin receptor and insulin receptor are coupled to activation of phosphatidylinositide3-kinase (PI3K) in POMC neurons, they are thought to have disparate actions on POMC excitability. Using whole-cell recording and selective pharmacological tools, we have found that similar to leptin, purified insulin depolarized POMC, and adjacent kisspeptin neurons via activation of TRPC5 channels, which are highly expressed in these neurons. In contrast, insulin hyperpolarized and inhibited NPY/AgRP neurons via activation of KATP channels. Moreover, Zn2+, which is found in insulin formulations at nanomolar concentrations, inhibited POMC neurons via activation of KATP channels. Finally as predicted, insulin given intracerebroventrically robustly inhibited food intake and activated c-fos expression in arcuate POMC neurons. Our results show that purified insulin excites POMC neurons in the arcuate nucleus, which we propose is a major mechanism by which insulin regulates energy homeostasis. PMID:24703699

  8. Role of Peroxisome Proliferator-Activated Receptor Gamma in Glucose-induced Insulin Secretion

    Institute of Scientific and Technical Information of China (English)

    Ze-Kuan XU; Neng-Guin CHEN; Chang-Yan MA; Zhuo-Xian MENG; Yu-Jie SUN; Xiao HAN

    2006-01-01

    Peroxisome proliferator-activated receptor (PPAR) isoforms (α and γ) are known to be expressed in pancreatic islets as well as in insulin-producing cell lines. Ligands of PPAR have been shown to enhance glucose-induced insulin secretion in rat pancreatic islets. However, their effect on insulin secretion is still unclear. To understand the molecular mechanism by which PPARγ exerts its effect on glucoseinduced insulin secretion, we examined the endogenous activity of PPAR isoforms, and studied the PPARγfunction and its target gene expression in INS-1 cells. We found that: (1) endogenous PPARγ was activated in a ligand-dependent manner in INS-1 cells; (2) overexpression of PPARγ in the absence of PPARγ ligands enhanced glucose-induced insulin secretion, which indicates that the increased glucose-induced insulin secretion is a PPARγ-mediated event; (3) the addition of both PPARγ and retinoid X receptor (RXR) ligands showed a synergistic effect on the augmentation of reporter activity, suggesting that the hetero-dimerization of PPARγand RXR is required for the regulation of the target genes; (4) PPARs upregulated both the glucose transporter 2 (GLUT2) and Cbl-associated protein (CAP) genes in INS-1 cells. Our findings suggest an important mechanistic pathway in which PPARγ enhances glucose-induced insulin secretion by activating the expression of GLUT2 and CAP genes in a ligand-dependent manner.

  9. Relationship between insulinase activity of erythrocytes and insulin resistance in patients with type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    LI Chen-zhong; ZHANG Su-hua; QIU Hong-xin; WANG Ding-nian

    2001-01-01

    To investigate the relationship between insulinase activity of erythrocytes (EIA) and insulin resistance in patients with type 2 diabetes mellitus. Methods: EIA was determined with the method of radioassay of enzyme activity in 65 healthy subjects, and 109 patients with type 2 diabetes mellitus divided into 3 subgroups according to their therapy and plasma glucose control. Fasting plasma insulin (FINS) and other related indices were also measured in all the subjects. Moreover, insulin sensitive index (lSI) was calculated for estimation of insulin sensitivity. Results: EIA and FINS are increased in two subgroups of diabetic patients on hypoglycemics (subgroup A and subgroup B), and especially higher in the poor controlled subgroup of patients ( subgroup A). EIA and FINS are normal in subgroup of patients without medication (subgroup C). Moreover, ISI is decreased in all the subgroups of patients as compared with normal subjects. Correlation analysis show that EIA is inversely correlated with ISI in all subgroups of patients and normal subjects, and positively correlated with FINS in normal subjects. Conclusions:The rate of insulin degradation in erythrocytes is increased in patients with type 2 diabetes, and increased insulin degradation may result in their insulin- resistant state. Moreover, EIA may be used as one of the indices for estimation of insulin sensitivity.

  10. Kupffer cells ameliorate hepatic insulin resistance induced by high-fat diet rich in monounsaturated fatty acids: the evidence for the involvement of alternatively activated macrophages

    Directory of Open Access Journals (Sweden)

    Papackova Zuzana

    2012-03-01

    Full Text Available Abstract Background Resident macrophages (Kupffer cells, KCs in the liver can undergo both pro- or anti-inflammatory activation pathway and exert either beneficiary or detrimental effects on liver metabolism. Until now, their role in the metabolically dysfunctional state of steatosis remains enigmatic. Aim of our study was to characterize the role of KCs in relation to the onset of hepatic insulin resistance induced by a high-fat (HF diet rich in monounsaturated fatty acids. Methods Male Wistar rats were fed either standard (SD or high-fat (HF diet for 4 weeks. Half of the animals were subjected to the acute GdCl3 treatment 24 and 72 hrs prior to the end of the experiment in order to induce the reduction of KCs population. We determined the effect of HF diet on activation status of liver macrophages and on the changes in hepatic insulin sensitivity and triacylglycerol metabolism imposed by acute KCs depletion by GdCl3. Results We found that a HF diet rich in MUFA itself triggers an alternative but not the classical activation program in KCs. In a steatotic, but not in normal liver, a reduction of the KCs population was associated with a decrease of alternative activation and with a shift towards the expression of pro-inflammatory activation markers, with the increased autophagy, elevated lysosomal lipolysis, increased formation of DAG, PKCε activation and marked exacerbation of HF diet-induced hepatic insulin resistance. Conclusions We propose that in the presence of a high MUFA content the population of alternatively activated resident liver macrophages may mediate beneficial effects on liver insulin sensitivity and alleviate the metabolic disturbances imposed by HF diet feeding and steatosis. Our data indicate that macrophage polarization towards an alternative state might be a useful strategy for treating type 2 diabetes.

  11. Design of an Active Ultrastable Single-chain Insulin Analog

    Science.gov (United States)

    Hua, Qing-xin; Nakagawa, Satoe H.; Jia, Wenhua; Huang, Kun; Phillips, Nelson B.; Hu, Shi-quan; Weiss, Michael A.

    2008-01-01

    Single-chain insulin (SCI) analogs provide insight into the inter-relation of hormone structure, function, and dynamics. Although compatible with wild-type structure, short connecting segments (design, structure, and function of a single-chain insulin analog (SCI-57) containing a 6-residue linker (GGGPRR). Native receptor-binding affinity (130 ± 8% relative to the wild type) is achieved as hindrance by the linker is offset by favorable substitutions in the insulin moiety. The thermodynamic stability of SCI-57 is markedly increased (ΔΔGu = 0.7 ± 0.1 kcal/mol relative to the corresponding two-chain analog and 1.9 ± 0.1 kcal/mol relative to wild-type insulin). Analysis of inter-residue nuclear Overhauser effects demonstrates that a native-like fold is maintained in solution. Surprisingly, the glycine-rich connecting segment folds against the insulin moiety: its central Pro contacts ValA3 at the edge of the hydrophobic core, whereas the final Arg extends the A1-A8 α-helix. Comparison between SCI-57 and its parent two-chain analog reveals striking enhancement of multiple native-like nuclear Overhauser effects within the tethered protein. These contacts are consistent with wild-type crystal structures but are ordinarily attenuated in NMR spectra of two-chain analogs, presumably due to conformational fluctuations. Linker-specific damping of fluctuations provides evidence for the intrinsic flexibility of an insulin monomer. In addition to their biophysical interest, ultrastable SCIs may enhance the safety and efficacy of insulin replacement therapy in the developing world. PMID:18332129

  12. Hypochlorous acid via peroxynitrite activates protein kinase Cθ and insulin resistance in adipocytes.

    Science.gov (United States)

    Zhou, Jun; Wang, Qilong; Ding, Ye; Zou, Ming-Hui

    2015-02-01

    We recently reported that genetic deletion of myeloperoxidase (MPO) alleviates obesity-related insulin resistance in mice in vivo. How MPO impairs insulin sensitivity in adipocytes is poorly characterized. As hypochlorous acid (HOCl) is a principal oxidant product generated by MPO, we evaluated the effects of HOCl on insulin signaling in adipocytes differentiated from 3T3-L1 cells. Exposure of 3T3-L1 adipocytes to exogenous HOCl (200 μmol/l) attenuated insulin-stimulated 2-deoxyglucose uptake, GLUT4 translocation, and insulin signals, including tyrosine phosphorylation of insulin receptor substrate 1 (IRS1) and phosphorylation of Akt. Furthermore, treatment with HOCl induced phosphorylation of IRS1 at serine 307, inhibitor κB kinase (IKK), c-Jun NH2-terminal kinase (JNK), and phosphorylation of PKCθ (PKCθ). In addition, genetic and pharmacological inhibition of IKK and JNK abolished serine phosphorylation of IRS1 and impairment of insulin signaling by HOCl. Furthermore, knockdown of PKCθ using siRNA transfection suppressed phosphorylation of IKK and JNK and consequently attenuated the HOCl-impaired insulin signaling pathway. Moreover, activation of PKCθ by peroxynitrite was accompanied by increased phosphorylation of IKK, JNK, and IRS1-serine 307. In contrast, ONOO(-) inhibitors abolished HOCl-induced phosphorylation of PKCθ, IKK, JNK, and IRS1-serine 307, as well as insulin resistance. Finally, high-fat diet (HFD)-induced insulin resistance was associated with enhanced phosphorylation of PKCθ, IKK, JNK, and IRS1 at serine 307 in white adipose tissues from WT mice, all of which were not found in Mpo knockout mice fed HFDs. We conclude that HOCl impairs insulin signaling pathway by increasing ONOO(-) mediated phosphorylation of PKCθ, resulting in phosphorylation of IKK/JNK and consequent serine phosphorylation of IRS1 in adipocytes.

  13. AMP-activated protein kinase (AMPK) regulates the insulin-induced activation of the nitric oxide synthase in human platelets.

    Science.gov (United States)

    Fleming, Ingrid; Schulz, Christian; Fichtlscherer, Birgit; Kemp, Bruce E; Fisslthaler, Beate; Busse, Rudi

    2003-11-01

    Little is known about the signaling cascades that eventually regulate the activity of the endothelial nitric oxide synthase (eNOS) in platelets. Here, we investigated the effects of insulin on the phosphorylation and activation of eNOS in washed human platelets and in endothelial cells. Insulin activated the protein kinase Akt in cultured endothelial cells and increased the phosphorylation of eNOS on Ser(1177) but failed to increase endothelial cyclic GMP levels or to elicit the relaxation of endothelium-intact porcine coronary arteries. In platelets, insulin also elicited the activation of Akt as well as the phosphorylation of eNOS and initiated NO production which was associated with increased cyclic GMP levels and the inhibition of thrombin-induced aggregation. The insulin-induced inhibition of aggregation was accompanied by a decreased Ca(2+) response to thrombin and was also prevented by N(omega) nitro-L-arginine. In platelets, but not in endothelial cells, insulin induced the activation of the AMP-activated protein kinase (AMPK), a metabolic stress-sensing kinase which was sensitive to the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin and the AMPK inhibitor iodotubercidin. Moreover, the insulin-mediated inhibition of thrombin-induced aggregation was prevented by iodotubercidin. Insulin-independent activation of the AMPK using 5-aminoimidazole-4-carboxamide ribonucleoside, increased platelet eNOS phosphorylation, increased cyclic GMP levels and attenuated platelet aggregation. These results highlight the differences in the signal transduction cascade activated by insulin in endothelial cells and platelets, and demonstrate that insulin stimulates the formation of NO in human platelets, in the absence of an increase in Ca(2+), by acti-vating PI3-K and AMPK which phosphorylates eNOS on Ser(1177).

  14. [Relationship between vasosympathetic activity and insulin resistance in normotensive and mildly hypertensive obese patients].

    Science.gov (United States)

    Valensi, P; Dabire, H; Brahimi, M; Paries, J; Platon, P; Attali, J R

    2001-08-01

    Several studies have well demonstrated that obesity is associated with changes in cardiovascular vagosympathetic activity. The aim of the present work was to evaluate this activity in normotensive and in mildly hypertensive obese patients, and to correlate this activity with clinical and biological indexes of insulin resistance. Heart rate (HR) and systolic blood pressure (sBP) were examined by spectral analysis in 70 normotensive obese patients (group 1), 32 mildly hypertensive obese patients (group 2), and 21 controls. The high frequency peak of HR variations at a controlled breathing rate (vagal activity) was significantly reduced in both groups (p < 0.001). The mid frequency peak of sBP in the standing position (sympathetic activity) was similar in both groups and in the control group. In groups 1 and 2, the high frequency peak correlated negatively with age (p = 0.005 and 0.034 respectively). In group 1, the mid frequency peak correlated positively with fat mass, fasting plasma insulin and triglyceride levels, and insulin resistance index (p < or = 0.03). In group 2, the mid frequency peak correlated positively with fasting insulin and insulin resistance index (p = 0.006 and 0.007 respectively). This study shows that, in obese patients: 1. cardiac vagal activity is reduced in normotensive and mildly hypertensive subjects; 2. vascular sympathetic activity is unchanged in means but may be increased as a consequence of adiposity, hyperinsulinemia and insulin resistance, and this increase is likely to be involved in the increase of blood pressure.

  15. ANTIDIABETIC AND HYPOLIPIDEMIC ACTIVITY OF GYMNEMA SYLVESTRE IN DEXAMETHASONE INDUCED INSULIN RESISTANCE IN ALBINO RATS

    OpenAIRE

    Hemanth Kumar V, Nagendra Nayak IM , Shobha V Huilgol, Saeed M Yendigeri , Narendar K

    2015-01-01

    Background: Gymnema sylvestre plant was widely used for medicinal purpose. The plant leaves were traditionally used to treat diabetes. Aim: To determine the antidiabetic and hypolipidemic activity of Gymnema sylvestre in dexamethasone induced insulin resistance in Albino rats. Objectives: The present study was undertaken to evaluate antidiabetic and hypolipidemic activity of Gymnema sylvestre leaf aqueous extract against dexamethasone induced insulin resistance in Albino rats. Materials and M...

  16. Prevention of obesity and insulin resistance in mice lacking plasminogen activator inhibitor 1.

    Science.gov (United States)

    Ma, Li-Jun; Mao, Su-Li; Taylor, Kevin L; Kanjanabuch, Talerngsak; Guan, YouFei; Zhang, YaHua; Brown, Nancy J; Swift, Larry L; McGuinness, Owen P; Wasserman, David H; Vaughan, Douglas E; Fogo, Agnes B

    2004-02-01

    Increased plasminogen activator inhibitor 1 (PAI-1) has been linked to not only thrombosis and fibrosis but also to obesity and insulin resistance. Increased PAI-1 levels have been presumed to be consequent to obesity. We investigated the interrelationships of PAI-1, obesity, and insulin resistance in a high-fat/high-carbohydrate (HF) diet-induced obesity model in wild-type (WT) and PAI-1-deficient mice (PAI-1(-/-)). Obesity and insulin resistance developing in WT mice on an HF diet were completely prevented in mice lacking PAI-1. PAI-1(-/-) mice on an HF diet had increased resting metabolic rates and total energy expenditure compared with WT mice, along with a marked increase in uncoupling protein 3 mRNA expression in skeletal muscle, likely mechanisms contributing to the prevention of obesity. In addition, insulin sensitivity was enhanced significantly in PAI-1(-/-) mice on an HF diet, as shown by euglycemic-hyperinsulinemic clamp studies. Peroxisome proliferator-activated receptor (PPAR)-gamma and adiponectin mRNA, key control molecules in lipid metabolism and insulin sensitivity, were maintained in response to an HF diet in white adipose tissue in PAI-1(-/-) mice, contrasting with downregulation in WT mice. This maintenance of PPAR-gamma and adiponectin may also contribute to the observed maintenance of body weight and insulin sensitivity in PAI-1(-/-) mice. Treatment in WT mice on an HF diet with the angiotensin type 1 receptor antagonist to downregulate PAI-1 indeed inhibited PAI-1 increases and ameliorated diet-induced obesity, hyperglycemia, and hyperinsulinemia. PAI-1 deficiency also enhanced basal and insulin-stimulated glucose uptake in adipose cells in vitro. Our data suggest that PAI-1 may not merely increase in response to obesity and insulin resistance, but may have a direct causal role in obesity and insulin resistance. Inhibition of PAI-1 might provide a novel anti-obesity and anti-insulin resistance treatment.

  17. Effects of insulin and exercise on muscle lipoprotein lipase activity in man and its relation to insulin action

    DEFF Research Database (Denmark)

    Kiens, Bente; Lithell, H; Mikines, K J;

    1989-01-01

    -induced increase in leg glucose uptake (r = 0.93, P less than 0.05). In the control group (n = 6) in which saline was infused in place of insulin and glucose, m-LPLA in nonexercised muscle did not change with time. No change in m-LPLA was observed immediately after one-legged knee extension exercise, but 4 h after......The effects of exercise and a physiological increase in plasma insulin concentration on muscle lipoprotein lipase activity (mLPLA), leg exchange of glucose, and serum lipoprotein levels were investigated in healthy young men. During euglycemic hyperinsulinemia (n = 7) at 44 mU.liter-1, m......-LPLA in non-exercised muscle decreased from 30 +/- 7.4 mU.g-1 wet weight (w.w.) (mean +/- SE) to 19 +/- 3.3 (P less than 0.05). Furthermore, the decrease in m-LPLA correlated closely (r = 0.97, P less than 0.05) with the increase in leg glucose uptake. Moreover, basal m-LPLA correlated with the insulin...

  18. Hepatic Insulin Resistance Following Chronic Activation of the CREB Coactivator CRTC2

    DEFF Research Database (Denmark)

    Hogan, Meghan F; Ravnskjaer, Kim; Matsumura, Shigenobu

    2015-01-01

    and dephosphorylation of the cAMP regulated CREB coactivators CRTC2 and CRTC3. In parallel, decreases in circulating insulin also increase gluconeogenic gene expression via the de-phosphorylation and activation of the forkhead transcription factor FOXO1. Hepatic gluconeogenesis is increased in insulin resistance where...... accompanying decreases in FOXO1 activity, hepatic gluconeogenic gene expression remained elevated in CRTC2S171,275A mice demonstrating that chronic increases in CRTC2 activity in the liver are indeed sufficient to promote hepatic insulin resistance and to disrupt glucose homeostasis....... increased gluconeogenic gene expression under fasting as well as feeding conditions. Circulating glucose concentrations were constitutively elevated in CRTC2S171,275A expressing mice, leading to compensatory increases in circulating insulin concentrations that enhance FOXO1 phosphorylation. Despite...

  19. Effect of recreational physical activity on insulin levels in Mexican/Hispanic children.

    Science.gov (United States)

    Macias-Cervantes, Maciste H; Malacara, Juan M; Garay-Sevilla, Ma Eugenia; Díaz-Cisneros, Francisco J

    2009-10-01

    The effect of increased recreational physical activity in children on insulin levels has not yet been studied. We carried out a randomized controlled trial in 76 children 6-9 years old, 32 of them increased their physical activity and 30 maintained the same level. In the intervention group, after a week of baseline, recreational activity three times/week was programmed for 12 weeks. We compared insulin, homeostatic model assessment (HOMA) index, glucose, HDL-C, LDL-C, triglycerides, and body mass index in both groups. Thereafter, we compared groups of normal weight, overweight, and with obesity in the experimental group. The group of recreational activity increased their median daily steps (15,329 to 19,910) and decreased insulin (p < 0.001) and HOMA index (4.36 vs. 2.39, p < 0.001). The diminution of insulin levels was more significant in the overweight group (p < 0.007). In conclusion, in our group, children who increased physical activity during 12 weeks decrease insulin levels and insulin resistance without change in other metabolic and anthropometric variables.

  20. The AMP-activated protein kinase α2 catalytic subunit controls whole-body insulin sensitivity

    Science.gov (United States)

    Viollet, Benoit; Andreelli, Fabrizio; Jørgensen, Sebastian B.; Perrin, Christophe; Geloen, Alain; Flamez, Daisy; Mu, James; Lenzner, Claudia; Baud, Olivier; Bennoun, Myriam; Gomas, Emmanuel; Nicolas, Gaël; Wojtaszewski, Jørgen F.P.; Kahn, Axel; Carling, David; Schuit, Frans C.; Birnbaum, Morris J.; Richter, Erik A.; Burcelin, Rémy; Vaulont, Sophie

    2003-01-01

    AMP-activated protein kinase (AMPK) is viewed as a fuel sensor for glucose and lipid metabolism. To better understand the physiological role of AMPK, we generated a knockout mouse model in which the AMPKα2 catalytic subunit gene was inactivated. AMPKα2–/– mice presented high glucose levels in the fed period and during an oral glucose challenge associated with low insulin plasma levels. However, in isolated AMPKα2–/– pancreatic islets, glucose- and L-arginine–stimulated insulin secretion were not affected. AMPKα2–/– mice have reduced insulin-stimulated whole-body glucose utilization and muscle glycogen synthesis rates assessed in vivo by the hyperinsulinemic euglycemic clamp technique. Surprisingly, both parameters were not altered in mice expressing a dominant-negative mutant of AMPK in skeletal muscle. Furthermore, glucose transport was normal in incubated isolated AMPKα2–/– muscles. These data indicate that AMPKα2 in tissues other than skeletal muscles regulates insulin action. Concordantly, we found an increased daily urinary catecholamine excretion in AMPKα2–/– mice, suggesting altered function of the autonomic nervous system that could explain both the impaired insulin secretion and insulin sensitivity observed in vivo. Therefore, extramuscular AMPKα2 catalytic subunit is important for whole-body insulin action in vivo, probably through modulation of sympathetic nervous activity. PMID:12511592

  1. The AMP-activated protein kinase alpha2 catalytic subunit controls whole-body insulin sensitivity.

    Science.gov (United States)

    Viollet, Benoit; Andreelli, Fabrizio; Jørgensen, Sebastian B; Perrin, Christophe; Geloen, Alain; Flamez, Daisy; Mu, James; Lenzner, Claudia; Baud, Olivier; Bennoun, Myriam; Gomas, Emmanuel; Nicolas, Gaël; Wojtaszewski, Jørgen F P; Kahn, Axel; Carling, David; Schuit, Frans C; Birnbaum, Morris J; Richter, Erik A; Burcelin, Rémy; Vaulont, Sophie

    2003-01-01

    AMP-activated protein kinase (AMPK) is viewed as a fuel sensor for glucose and lipid metabolism. To better understand the physiological role of AMPK, we generated a knockout mouse model in which the AMPKalpha2 catalytic subunit gene was inactivated. AMPKalpha2(-/-) mice presented high glucose levels in the fed period and during an oral glucose challenge associated with low insulin plasma levels. However, in isolated AMPKalpha2(-/-) pancreatic islets, glucose- and L-arginine-stimulated insulin secretion were not affected. AMPKalpha2(-/-) mice have reduced insulin-stimulated whole-body glucose utilization and muscle glycogen synthesis rates assessed in vivo by the hyperinsulinemic euglycemic clamp technique. Surprisingly, both parameters were not altered in mice expressing a dominant-negative mutant of AMPK in skeletal muscle. Furthermore, glucose transport was normal in incubated isolated AMPKalpha2(-/-) muscles. These data indicate that AMPKalpha2 in tissues other than skeletal muscles regulates insulin action. Concordantly, we found an increased daily urinary catecholamine excretion in AMPKalpha2(-/-) mice, suggesting altered function of the autonomic nervous system that could explain both the impaired insulin secretion and insulin sensitivity observed in vivo. Therefore, extramuscular AMPKalpha2 catalytic subunit is important for whole-body insulin action in vivo, probably through modulation of sympathetic nervous activity.

  2. Reduced DPP4 activity improves insulin signaling in primary human adipocytes.

    Science.gov (United States)

    Röhrborn, Diana; Brückner, Julia; Sell, Henrike; Eckel, Jürgen

    2016-03-11

    DPP4 is a ubiquitously expressed cell surface protease which is also released to the circulation as soluble DPP4 (sDPP4). Recently, we identified DPP4 as a novel adipokine oversecreted in obesity and thus potentially linking obesity to the metabolic syndrome. Furthermore, sDPP4 impairs insulin signaling in an autocrine and paracrine fashion in different cell types. However, it is still unknown which functional role DPP4 might play in adipocytes. Therefore, primary human adipocytes were treated with a specific DPP4 siRNA. Adipocyte differentiation was not affected by DPP4 silencing. Interestingly, DPP4 reduction improved insulin responsiveness of adipocytes at the level of insulin receptor, proteinkinase B (Akt) and Akt substrate of 160 kDa. To investigate whether the observed effects could be attributed to the enzymatic activity of DPP4, human adipocytes were treated with the DPP4 inhibitors sitagliptin and saxagliptin. Our data show that insulin-stimulated activation of Akt is augmented by DPP4 inhibitor treatment. Based on our previous observation that sDPP4 induces insulin resistance in adipocytes, and that adipose DPP4 levels are higher in obese insulin-resistant patients, we now suggest that the abundance of DPP4 might be a regulator of adipocyte insulin signaling.

  3. Exacerbated cardiac fibrosis induced by β-adrenergic activation in old mice due to decreased AMPK activity.

    Science.gov (United States)

    Wang, Jingjing; Song, Yao; Li, Hao; Shen, Qiang; Shen, Jing; An, Xiangbo; Wu, Jimin; Zhang, Jianshu; Wu, Yunong; Xiao, Han; Zhang, Youyi

    2016-11-01

    Senescent hearts exhibit defective responses to β-adrenergic receptor (β-AR) over-activation upon stress, leading to more severe pathological cardiac remodelling. However, the underlying mechanisms remain unclear. Here, we investigated the role of adenosine monophosphate-activated protein kinase (AMPK) in protecting against ageing-associated cardiac remodelling in mice upon β-AR over-activation. 10-week-old (young) and 18-month-old (old) mice were subcutaneously injected with the β-AR agonist isoproterenol (ISO; 5 mg/kg). More extensive cardiac fibrosis was found in old mice upon ISO exposure than in young mice. Meanwhile, ISO treatment decreased AMPK activity and increased β-arrestin 1, but not β-arrestin 2, expression, and the effects of ISO on AMPK and β-arrestin 1 were greater in old mice than in young mice. Similarly, young AMPKα2-knockout (KO) mice showed more extensive cardiac fibrosis upon ISO exposure than that was observed in age-matched wild-type (WT) littermates. The extent of cardiac fibrosis in WT old mice was similar to that in young KO mice. Additionally, AMPK activities were decreased and β-arrestin 1 expression increased in KO mice. In contrast, the AMPK activator metformin decreased β-arrestin 1 expression and attenuated cardiac fibrosis in both young and old mice upon ISO exposure. In conclusion, more severe cardiac fibrosis is induced by ISO in old mice than in young mice. A decrease in AMPK activity, which further increases β-arrestin 1 expression, is the central mechanism underlying the ageing-related cardiac fibrosis induced by ISO. The AMPK activator metformin is a promising therapeutic agent for treating ageing-related cardiac remodelling upon β-AR over-activation.

  4. Elucidating the Activation Mechanism of the Insulin-Family Proteins with Molecular Dynamics Simulations.

    Science.gov (United States)

    Papaioannou, Anastasios; Kuyucak, Serdar; Kuncic, Zdenka

    2016-01-01

    The insulin-family proteins bind to their own receptors, but insulin-like growth factor II (IGF-II) can also bind to the A isoform of the insulin receptor (IR-A), activating unique and alternative signaling pathways from those of insulin. Although extensive studies of insulin have revealed that its activation is associated with the opening of the B chain-C terminal (BC-CT), the activation mechanism of the insulin-like growth factors (IGFs) still remains unknown. Here, we present the first comprehensive study of the insulin-family proteins comparing their activation process and mechanism using molecular dynamics simulations to reveal new insights into their specificity to the insulin receptor. We have found that all the proteins appear to exhibit similar stochastic dynamics in their conformational change to an active state. For the IGFs, our simulations show that activation involves two opening locations: the opening of the BC-CT section away from the core, similar to insulin; and the additional opening of the BC-CT section away from the C domain. Furthermore, we have found that these two openings occur simultaneously in IGF-I, but not in IGF-II, where they can occur independently. This suggests that the BC-CT section and the C domain behave as a unified domain in IGF-I, but as two independent domains in IGF-II during the activation process, implying that the IGFs undergo different activation mechanisms for receptor binding. The probabilities of the active and inactive states of the proteins suggest that IGF-II is hyperactive compared to IGF-I. The hinge residue and the hydrophobic interactions in the core are found to play a critical role in the stability and activity of IGFs. Overall, our simulations have elucidated the crucial differences and similarities in the activation mechanisms of the insulin-family proteins, providing new insights into the molecular mechanisms responsible for the observed differences between IGF-I and IGF-II in receptor binding.

  5. Elucidating the Activation Mechanism of the Insulin-Family Proteins with Molecular Dynamics Simulations

    Science.gov (United States)

    Papaioannou, Anastasios; Kuyucak, Serdar; Kuncic, Zdenka

    2016-01-01

    The insulin-family proteins bind to their own receptors, but insulin-like growth factor II (IGF-II) can also bind to the A isoform of the insulin receptor (IR-A), activating unique and alternative signaling pathways from those of insulin. Although extensive studies of insulin have revealed that its activation is associated with the opening of the B chain-C terminal (BC-CT), the activation mechanism of the insulin-like growth factors (IGFs) still remains unknown. Here, we present the first comprehensive study of the insulin-family proteins comparing their activation process and mechanism using molecular dynamics simulations to reveal new insights into their specificity to the insulin receptor. We have found that all the proteins appear to exhibit similar stochastic dynamics in their conformational change to an active state. For the IGFs, our simulations show that activation involves two opening locations: the opening of the BC-CT section away from the core, similar to insulin; and the additional opening of the BC-CT section away from the C domain. Furthermore, we have found that these two openings occur simultaneously in IGF-I, but not in IGF-II, where they can occur independently. This suggests that the BC-CT section and the C domain behave as a unified domain in IGF-I, but as two independent domains in IGF-II during the activation process, implying that the IGFs undergo different activation mechanisms for receptor binding. The probabilities of the active and inactive states of the proteins suggest that IGF-II is hyperactive compared to IGF-I. The hinge residue and the hydrophobic interactions in the core are found to play a critical role in the stability and activity of IGFs. Overall, our simulations have elucidated the crucial differences and similarities in the activation mechanisms of the insulin-family proteins, providing new insights into the molecular mechanisms responsible for the observed differences between IGF-I and IGF-II in receptor binding. PMID

  6. Anti-diabetic activity of insulin-degrading enzyme inhibitors mediated by multiple hormones.

    Science.gov (United States)

    Maianti, Juan Pablo; McFedries, Amanda; Foda, Zachariah H; Kleiner, Ralph E; Du, Xiu Quan; Leissring, Malcolm A; Tang, Wei-Jen; Charron, Maureen J; Seeliger, Markus A; Saghatelian, Alan; Liu, David R

    2014-07-03

    Despite decades of speculation that inhibiting endogenous insulin degradation might treat type-2 diabetes, and the identification of IDE (insulin-degrading enzyme) as a diabetes susceptibility gene, the relationship between the activity of the zinc metalloprotein IDE and glucose homeostasis remains unclear. Although Ide(-/-) mice have elevated insulin levels, they exhibit impaired, rather than improved, glucose tolerance that may arise from compensatory insulin signalling dysfunction. IDE inhibitors that are active in vivo are therefore needed to elucidate IDE's physiological roles and to determine its potential to serve as a target for the treatment of diabetes. Here we report the discovery of a physiologically active IDE inhibitor identified from a DNA-templated macrocycle library. An X-ray structure of the macrocycle bound to IDE reveals that it engages a binding pocket away from the catalytic site, which explains its remarkable selectivity. Treatment of lean and obese mice with this inhibitor shows that IDE regulates the abundance and signalling of glucagon and amylin, in addition to that of insulin. Under physiological conditions that augment insulin and amylin levels, such as oral glucose administration, acute IDE inhibition leads to substantially improved glucose tolerance and slower gastric emptying. These findings demonstrate the feasibility of modulating IDE activity as a new therapeutic strategy to treat type-2 diabetes and expand our understanding of the roles of IDE in glucose and hormone regulation.

  7. Role of signal transducer and activator of transcription 1 in murine allergen-induced airway remodeling and exacerbation by carbon nanotubes.

    Science.gov (United States)

    Thompson, Elizabeth A; Sayers, Brian C; Glista-Baker, Ellen E; Shipkowski, Kelly A; Ihrie, Mark D; Duke, Katherine S; Taylor, Alexia J; Bonner, James C

    2015-11-01

    Asthma is characterized by a T helper type 2 phenotype and by chronic allergen-induced airway inflammation (AAI). Environmental exposure to air pollution ultrafine particles (i.e., nanoparticles) exacerbates AAI, and a concern is possible exacerbation posed by engineered nanoparticles generated by emerging nanotechnologies. Signal transducer and activator of transcription (STAT) 1 is a transcription factor that maintains T helper type 1 cell development. However, the role of STAT1 in regulating AAI or exacerbation by nanoparticles has not been explored. In this study, mice with whole-body knockout of the Stat1 gene (Stat1(-/-)) or wild-type (WT) mice were sensitized to ovalbumin (OVA) allergen and then exposed to multiwalled carbon nanotubes (MWCNTs) by oropharygneal aspiration. In Stat1(-/-) and WT mice, OVA increased eosinophils in bronchoalveolar lavage fluid, whereas MWCNTs increased neutrophils. Interestingly, OVA sensitization prevented MWCNT-induced neutrophilia and caused only eosinophilic inflammation. Stat1(-/-) mice displayed increased IL-13 in bronchoalveolar lavage fluid at 1 day compared with WT mice after treatment with OVA or OVA and MWCNTs. At 21 days, the lungs of OVA-sensitized Stat1(-/-) mice displayed increased eosinophilia, goblet cell hyperplasia, airway fibrosis, and subepithelial apoptosis. MWCNTs further increased OVA-induced goblet cell hyperplasia, airway fibrosis, and apoptosis in Stat1(-/-) mice at 21 days. These changes corresponded to increased levels of profibrogenic mediators (transforming growth factor-β1, TNF-α, osteopontin) but decreased IL-10 in Stat1(-/-) mice. Finally, fibroblasts isolated from the lungs of Stat1(-/-) mice produced significantly more collagen mRNA and protein in response to transforming growth factor-β1 compared with WT lung fibroblasts. Our results support a protective role for STAT1 in chronic AAI and exacerbation of remodeling caused by MWCNTs.

  8. Erdosteine for COPD exacerbations.

    Science.gov (United States)

    2008-10-01

    The mucolytic drug erdosteine (Erdotin - Galen) is licensed in the UK as treatment for up to 10 days "for the symptomatic treatment of acute exacerbations of chronic bronchitis in adults". This indication differs from that for carbocisteine and mecysteine, two older mucolytic drugs that are licensed for adjunctive treatment in respiratory disorders characterised by viscous mucus, and typically used for longer to prevent exacerbations of chronic obstructive pulmonary disease (COPD). Does erdosteine have a role for people with COPD exacerbations?

  9. Identification of a small molecule activator of novel PKCs for promoting glucose-dependent insulin secretion

    Institute of Scientific and Technical Information of China (English)

    Shuai Han; Heling Pan; Jianhua Zhang; Li Tan; Dawei Ma; Junying Yuan; Jia-Rui Wu

    2011-01-01

    Using an image-based screen for small molecules that can affect Golgi morphology, we identify a small molecule,Sioc145, which can enlarge the Golgi compartments and promote protein secretion. More importantly, Siocl45 potentiates insulin secretion in a glucose-dependent manner. We show that Sioc145 selectively activates novel protein kinase Cs (nPKCs; δ and ε) but not conventional PKCs;cPKCs; a, βI and βll) in INS-1E insulinoma cells. In contrast, PMA, a non-selective activator of cPKCs and nPKCs, promotes insulin secretion independent of glucose concentrations. Furthermore, we demonstrate that Sioc145 and PMA show differential abilities in depolarizing the cell membrane, and suggest that Sioc145 promotes insulin secretion in the amplifying pathway downstream of K ATp channels. In pancreatic islets, the treatment with Sioc145 enhances the second phase of insulin secretion. Increased insulin granules close to the plasma membrane are observed after Sioc145 treatment. Finally, the administration of Sioc145 to diabetic GK rats increases their serum insulin levels and improves glucose tolerance. Collectively, our studies identify Sioc145 as a novel glucose-dependent insulinotropic compound via selectively activating nPKCs.

  10. Effects of breed and zeranol implantation on serum insulin, somatomedin-like activity and fibroblast proliferative activity.

    Science.gov (United States)

    Wangsness, P J; Olsen, R F; Martin, R J

    1981-01-01

    Twenty-eight Suffolk-sired (Sx) and 28 Finnsheep-sired (Fx) lambs were implanted with either 0 or 12 mg zeranol. Zeranol significantly increased average daily gain over that of controls. Serum taken at biweekly intervals for 6 weeks was assayed for insulin, somatomedin-like activity (Sm) and fibroblast proliferative activity (FPA). Insulin appeared to increase with time, but there were no consistent time changes for FPA or Sm. Serum insulin concentration was higher (P less than .05) in implanted lambs than in controls (33.4 vs 25.6 microU/ml). Unlike insulin, serum Sm and FPA were not affected by zeranol implantation, and, thus, these serum factors appeared not to be involved in zeranol-stimulated growth. Sm was higher in the faster growing Sx lambs than in the slower growing Fx lambs. Thus, serum Sm activity may be involved in normal regulation of growth.

  11. Immunization of allogeneic bone marrow transplant recipients with tumor cell vaccines enhances graft-versus-tumor activity without exacerbating graft-versus-host disease.

    Science.gov (United States)

    Anderson, L D; Savary, C A; Mullen, C A

    2000-04-01

    Allogeneic bone marrow transplantation (BMT) induces 2 closely associated immune responses: graft-versus-tumor (GVT) activity and graft-versus-host disease (GVHD). We have previously shown that pretransplant immunization of allogeneic BMT donors with a recipient-derived tumor cell vaccine increases both GVT activity and lethal GVHD because of the priming of donor T cells against putative minor histocompatibility antigens (mHAgs) on the tumor vaccine cells. The work reported here tested the hypothesis that tumor cell vaccination after BMT would produce an increase in GVT activity without exacerbating GVHD. C3H.SW donor bone marrow and splenocytes were transplanted into major histocompatibility complex-matched, mHAg-mismatched C57BL/6 recipients. One month after BMT, recipients were immunized against either a C57BL/6 myeloid leukemia (C1498) or fibrosarcoma (205). Immunized recipients had a significant increase in survival and protection against tumor growth in both tumor models, and significant tumor protection was seen even in recipients with preexisting micrometastatic cancer before immunization. Alloreactivity appeared to contribute to the in vitro anti-tumor cytolytic activity, but in vivo immunity was tumor specific, and no exacerbation of GVHD was observed. Although the immunodominant mHAg B6(dom1) was shown to be expressed by all B6 tumors tested and was largely responsible for the alloreactivity resulting from tumor immunization of donors, the in vitro alloreactivity of immune recipients was more restricted and was not mediated by recognition of B6(dom1). In conclusion, post-transplant tumor immunization of allogeneic BMT recipients against either a leukemia or a solid tumor can increase GVT activity and survival without exacerbating GVHD.

  12. Constitutively active heat shock factor 1 enhances glucose-driven insulin secretion.

    Science.gov (United States)

    Uchiyama, Tsuyoshi; Tomono, Shoichi; Utsugi, Toshihiro; Ohyama, Yoshio; Nakamura, Tetsuya; Tomura, Hideaki; Kawazu, Shoji; Okajima, Fumikazu; Kurabayashi, Masahiko

    2011-06-01

    Weak pancreatic β-cell function is a cause of type 2 diabetes mellitus. Glucokinase regulates insulin secretion via phosphorylation of glucose. The present study focused on a system for the self-protection of pancreatic cell by expressing heat shock factor (HSF) and heat shock protein (HSP) to improve insulin secretion without inducing hypoglycemia. We previously generated a constitutively active form of human HSF1 (CA-hHSF1). An adenovirus expressing CA-hHSF1 using the cytomegalovirus promoter was generated to infect mouse insulinoma cells (MIN6 cells). An adenovirus expressing CA-hHSF1 using a human insulin promoter (Ins-CA-hHSF1) was also generated to infect rats. We investigated whether CA-hHSF1 induces insulin secretion in MIN6 cells and whether Ins-CA-hHSF1 can improve blood glucose and serum insulin levels in healthy Wister rats and type 2 diabetes mellitus model rats. CA-hHSF1 expression increased insulin secretion 1.27-fold compared with the overexpression of wild-type hHSF1 in MIN6 cells via induction of HSP90 expression and subsequent activation of glucokinase. This mechanism is associated with activation of both glucokinase and neuronal nitric oxide synthase. Ins-CA-hHSF1 improved blood glucose levels in neonatal streptozotocin-induced diabetic rats. Furthermore, Ins-CA-hHSF1 reduced oral glucose tolerance testing results in healthy Wister rats because of an insulin spike at 15 minutes; however, it did not induce hypoglycemia. CA-hHSF1 induced insulin secretion both in vitro and in vivo. These findings suggest that gene therapy with Ins-CA-hHSF1 will be able to be used to treat patients with type 2 diabetes mellitus and impaired glucose tolerance without causing hypoglycemia at fasting. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. FGF19 as a postprandial, insulin-independent activator of hepatic protein and glycogen synthesis.

    Science.gov (United States)

    Kir, Serkan; Beddow, Sara A; Samuel, Varman T; Miller, Paul; Previs, Stephen F; Suino-Powell, Kelly; Xu, H Eric; Shulman, Gerald I; Kliewer, Steven A; Mangelsdorf, David J

    2011-03-25

    Fibroblast growth factor (FGF) 19 is an enterokine synthesized and released when bile acids are taken up into the ileum. We show that FGF19 stimulates hepatic protein and glycogen synthesis but does not induce lipogenesis. The effects of FGF19 are independent of the activity of either insulin or the protein kinase Akt and, instead, are mediated through a mitogen-activated protein kinase signaling pathway that activates components of the protein translation machinery and stimulates glycogen synthase activity. Mice lacking FGF15 (the mouse FGF19 ortholog) fail to properly maintain blood concentrations of glucose and normal postprandial amounts of liver glycogen. FGF19 treatment restored the loss of glycogen in diabetic animals lacking insulin. Thus, FGF19 activates a physiologically important, insulin-independent endocrine pathway that regulates hepatic protein and glycogen metabolism.

  14. Potential efficacy of Lactobacillus casei IBRC_M10711 on expression and activity of insulin degrading enzyme but not insulin degradation.

    Science.gov (United States)

    Neyazi, Nadia; Mohammadi Farsani, Taiebeh; Nouri, Zahra; Ghahremani, Mohammad Hossein; Khorramizadeh, Mohammad Reza; Tajerian, Roksana; Motevaseli, Elahe

    2017-01-01

    Type 2 diabetes (T2D) is a condition with insufficient insulin production or in the setting of insulin resistance with many origins including intestinal microbiota-related molecular mechanism. Insulin-degrading enzyme (IDE) is responsible for insulin breakdown in various tissues and is known as a potential drug target for T2D. Here, we assessed the effects of cell-free supernatant (CFS) and UV-killed Lactobacillus casei IBRC_M10711 on IDE expression, IDE activity, and insulin degradation in Caco-2 cell line. It was found that CFS and UV-killed L. casei IBRC_M10711 led to lower expression of IDE. UV-killed L. casei IBRC_M10711 significantly inhibited IDE activity but CFS did not. Insulin degradation was affected with none of them. In conclusion, L. casei IBRC_M10711 is effective on IDE expression and its activity, but not on insulin degradation. Future studies are recommended to explore the effect of this probiotic on other substrates of IDE.

  15. Insulin induces drug resistance in melanoma through activation of the PI3K/Akt pathway

    Directory of Open Access Journals (Sweden)

    Chi M

    2014-02-01

    Full Text Available Mengna Chi,1 Yan Ye,1 Xu Dong Zhang,1 Jiezhong Chen2,3 1School of Medicine and Public Health, The University of Newcastle, Newcastle, NSW, Australia; 2School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia; 3Faculty of Science, Medicine and Health, The University of Wollongong, Wollongong, NSW, Australia Introduction: There is currently no curative treatment for melanoma once the disease spreads beyond the original site. Although activation of the PI3K/Akt pathway resulting from genetic mutations and epigenetic deregulation of its major regulators is known to cause resistance of melanoma to therapeutic agents, including the conventional chemotherapeutic drug dacarbazine and the Food and Drug Administration-approved mutant BRAF inhibitors vemurafenib and dabrafenib, the role of extracellular stimuli of the pathway, such as insulin, in drug resistance of melanoma remains less understood. Objective: To investigate the effect of insulin on the response of melanoma cells to dacarbazine, and in particular, the effect of insulin on the response of melanoma cells carrying the BRAFV600E mutation to mutant BRAF inhibitors. An additional aim was to define the role of the PI3K/Akt pathway in the insulin-triggered drug resistance. Methods: The effect of insulin on cytotoxicity induced by dacarbazine or the mutant BRAF inhibitor PLX4720 was tested by pre-incubation of melanoma cells with insulin. Cytotoxicity was determined by the MTS assay. The role of the PI3K/Akt pathway in the insulin-triggered drug resistance was examined using the PI3K inhibitor LY294002 and the PI3K and mammalian target of rapamycin dual inhibitor BEZ-235. Activation of the PI3K/Akt pathway was monitored by Western blot analysis of phosphorylated levels of Akt. Results: Recombinant insulin attenuated dacarbazine-induced cytotoxicity in both wild-type BRAF and BRAFV600E melanoma cells, whereas it also reduced killing of BRAFV600E melanoma cells by PLX4720

  16. A telehealth program for self-management of COPD exacerbations and promotion of an active lifestyle: a pilot randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Tabak M

    2014-09-01

    Full Text Available Monique Tabak,1,2 Marjolein Brusse-Keizer,3 Paul van der Valk,3,4 Hermie Hermens,1,2 Miriam Vollenbroek-Hutten1,2 1Telemedicine Group, Roessingh Research and Development, 2Telemedicine Group, University of Twente, 3Department of Pulmonary Medicine, Medisch Spectrum Twente, 4Medical School Twente, Medisch Spectrum Twente, Enschede, the Netherlands Abstract: The objective of this pilot study was to investigate the use of and satisfaction with a chronic obstructive pulmonary disease (COPD telehealth program applied in both primary and secondary care. The program consisted of four modules: 1 activity coach for ambulant activity monitoring and real-time coaching of daily activity behavior, 2 web-based exercise program for home exercising, 3 self-management of COPD exacerbations via a triage diary on the web portal, including self-treatment of exacerbations, and 4 teleconsultation. Twenty-nine COPD patients were randomly assigned to either the intervention group (telehealth program for 9 months or the control group (usual care. Page hits on the web portal showed the use of the program, and the Client Satisfaction Questionnaire showed satisfaction with received care. The telehealth program with decision support showed good satisfaction (mean 26.4, maximum score 32. The program was accessed on 86% of the treatment days, especially the diary. Patient adherence with the exercise scheme was low (21%. Health care providers seem to play an important role in patients' adherence to telehealth in usual care. Future research should focus on full-scale implementation in daily care and investigating technological advances, like gaming, to increase adherence. Keywords: COPD, physical activity, exacerbations, telehealth, self-management

  17. Novel method demonstrates differential ligand activation and phosphatase-mediated deactivation of insulin receptor tyrosine-specific phosphorylation.

    Science.gov (United States)

    Cieniewicz, Anne M; Cooper, Philip R; McGehee, Jennifer; Lingham, Russell B; Kihm, Anthony J

    2016-08-01

    Insulin receptor signaling is a complex cascade leading to a multitude of intracellular functional responses. Three natural ligands, insulin, IGF1 and IGF2, are each capable of binding with different affinities to the insulin receptor, and result in variable biological responses. However, it is likely these affinity differences alone cannot completely explain the myriad of diverse cellular outcomes. Ligand binding initiates activation of a signaling cascade resulting in phosphorylation of the IR itself and other intracellular proteins. The direct catalytic activity along with the temporally coordinated assembly of signaling proteins is critical for insulin receptor signaling. We hypothesized that determining differential phosphorylation among individual tyrosine sites activated by ligand binding or dephosphorylation by phosphatases could provide valuable insight into insulin receptor signaling. Here, we present a sensitive, novel immunoassay adapted from Meso Scale Discovery technology to quantitatively measure changes in site-specific phosphorylation levels on endogenous insulin receptors from HuH7 cells. We identified insulin receptor phosphorylation patterns generated upon differential ligand activation and phosphatase-mediated deactivation. The data demonstrate that insulin, IGF1 and IGF2 elicit different insulin receptor phosphorylation kinetics and potencies that translate to downstream signaling. Furthermore, we show that insulin receptor deactivation, regulated by tyrosine phosphatases, occurs distinctively across specific tyrosine residues. In summary, we present a novel, quantitative and high-throughput assay that has uncovered differential ligand activation and site-specific deactivation of the insulin receptor. These results may help elucidate some of the insulin signaling mechanisms, discriminate ligand activity and contribute to a better understanding of insulin receptor signaling. We propose this methodology as a powerful approach to characterize

  18. Increased IL-1β activation, the culprit not only for defective insulin secretion but also for insulin resistance?

    Institute of Scientific and Technical Information of China (English)

    Marianne B(o)ni-Schnetzler; Marc Y Donath

    2011-01-01

    @@ Type 2 diabetes is a chronic progressive disease characterized by insufficient insulin secretion to compensate for insulin resistance.The onset of type 2 diabetes and its progression are mainly determined by the progressive failure of the pancreatic islet β-cells to produce sufficient levels of insulin.

  19. CYP24A1 exacerbated activity during diabetes contributes to kidney tubular apoptosis via caspase-3 increased expression and activation.

    Directory of Open Access Journals (Sweden)

    Alexandre Tourigny

    Full Text Available Decreases in circulating 25,hydroxyl-vitamin D3 (25 OH D3 and 1,25,dihydroxyl-vitamin D3 (1,25 (OH2 D3 have been extensively documented in patients with type 2 diabetes. Nevertheless, the molecular reasons behind this drop, and whether it is a cause or an effect of disease progression is still poorly understood. With the skin and the liver, the kidney is one of the most important sites for vitamin D metabolism. Previous studies have also shown that CYP24A1 (an enzyme implicated in vitamin D metabolism, might play an important role in furthering the progression of kidney lesions during diabetic nephropathy. In this study we show a link between CYP24A1 increase and senescence followed by apoptosis induction in the renal proximal tubules of diabetic kidneys. We show that CYP24A1 expression was increased during diabetic nephropathy progression. This increase derived from protein kinase C activation and increased H(2O(2 cellular production. CYP24A1 increase had a major impact on cellular phenotype, by pushing cells into senescence, and later into apoptosis. Our data suggest that control of CYP24A1 increase during diabetes has a beneficial effect on senescence induction and caspase-3 increased expression. We concluded that diabetes induces an increase in CYP24A1 expression, destabilizing vitamin D metabolism in the renal proximal tubules, leading to cellular instability and apoptosis, and thereby accelerating tubular injury progression during diabetic nephropathy.

  20. Insulin, macronutrient intake, and physical activity: are potential indicators of insulin resistance associated with mortality from breast cancer?

    Science.gov (United States)

    Borugian, Marilyn J; Sheps, Samuel B; Kim-Sing, Charmaine; Van Patten, Cheri; Potter, John D; Dunn, Bruce; Gallagher, Richard P; Hislop, T Gregory

    2004-07-01

    High levels of insulin have been associated with increased risk of breast cancer, and poorer survival after diagnosis. Data and sera were collected from 603 breast cancer patients, including information on diet and physical activity, medical history, family history, demographic, and reproductive risk factors. These data were analyzed to test the hypothesis that excess insulin and related factors are directly related to mortality after a diagnosis of breast cancer. The cohort was recruited from breast cancer patients treated at the British Columbia Cancer Agency between July 1991 and December 1992. Questionnaire and medical record data were collected at enrollment and outcomes were ascertained by linkage to the BC Cancer Registry after 10 years of follow-up. The primary outcome of interest was breast cancer-specific mortality (n = 112). Lifestyle data were analyzed using Cox proportional hazards regression models to relate risk factors to outcomes, controlling for potential confounders, such as age and stage at diagnosis. Data for biological variables were analyzed as a nested case-control study due to limited serum volumes, with at least one survivor from the same cohort as a control for each breast cancer death, matched on stage and length of follow-up. High levels of insulin were associated with poorer survival for postmenopausal women [odds ratio, 1.9; 95% confidence interval (CI), 0.7-6.6, comparing highest to lowest tertile, P trend = 0.10], while high dietary fat intake was associated with poorer survival for premenopausal women (relative risk, 4.8; 95% CI, 1.3-18.1, comparing highest to lowest quartile). Higher dietary protein intake was associated with better survival for all women (relative risk, 0.4; 95% CI, 0.2-0.8, comparing highest to lowest quartile).

  1. Sam68 Mediates the Activation of Insulin and Leptin Signalling in Breast Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Antonio Pérez-Pérez

    Full Text Available Obesity is a well-known risk factor for breast cancer development in postmenopausal women. High insulin and leptin levels seem to have a role modulating the growth of these tumours. Sam68 is an RNA-binding protein with signalling functions that has been found to be overexpressed in breast cancer. Moreover, Sam68 may be recruited to insulin and leptin signalling pathways, mediating its effects on survival, growth and proliferation in different cellular types. We aimed to study the expression of Sam68 and its phosphorylation level upon insulin and leptin stimulation, and the role of Sam68 in the proliferative effect and signalling pathways that are activated by insulin or leptin in human breast adenocarcinoma cells. In the human breast adenocarcinoma cell lines MCF7, MDA-MB-231 and BT-474, Sam68 protein quantity and gene expression were increased upon leptin or insulin stimulation, as it was checked by qPCR and immunoblot. Moreover, both insulin and leptin stimulation promoted an increase in Sam68 tyrosine phosphorylation and negatively regulated its RNA binding capacity. siRNA was used to downregulate Sam68 expression, which resulted in lower proliferative effects of both insulin and leptin, as well as a lower activation of MAPK and PI3K pathways promoted by both hormones. These effects may be partly explained by the decrease in IRS-1 expression by down-regulation of Sam68. These results suggest the participation of Sam68 in both leptin and insulin receptor signaling in human breast cancer cells, mediating the trophic effects of these hormones in proliferation and cellular growth.

  2. The Guanine Nucleotide Exchange Factor ARNO mediates the activation of ARF and phospholipase D by insulin

    Science.gov (United States)

    Li, Hai-Sheng; Shome, Kuntala; Rojas, Raúl; Rizzo, Mark A; Vasudevan, Chandrasekaran; Fluharty, Eric; Santy, Lorraine C; Casanova, James E; Romero, Guillermo

    2003-01-01

    Background Phospholipase D (PLD) is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF) family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs) of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin. Results Wild type ARNO transiently transfected in HIRcB cells was translocated to the plasma membrane in an insulin-dependent manner and promoted the translocation of ARF to the membranes. ARNO mutants: ΔCC-ARNO and CC-ARNO were partially translocated to the membranes while ΔPH-ARNO and PH-ARNO could not be translocated to the membranes. Sec7 domain mutants of ARNO did not facilitate the ARF translocation. Overexpression of wild type ARNO significantly increased insulin-stimulated PLD activity, and mutations in the Sec7 and PH domains, or deletion of the PH or CC domains inhibited the effects of insulin. Conclusions Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor. PMID:12969509

  3. The Guanine Nucleotide Exchange Factor ARNO mediates the activation of ARF and phospholipase D by insulin

    Directory of Open Access Journals (Sweden)

    Fluharty Eric

    2003-09-01

    Full Text Available Abstract Background Phospholipase D (PLD is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin. Results Wild type ARNO transiently transfected in HIRcB cells was translocated to the plasma membrane in an insulin-dependent manner and promoted the translocation of ARF to the membranes. ARNO mutants: ΔCC-ARNO and CC-ARNO were partially translocated to the membranes while ΔPH-ARNO and PH-ARNO could not be translocated to the membranes. Sec7 domain mutants of ARNO did not facilitate the ARF translocation. Overexpression of wild type ARNO significantly increased insulin-stimulated PLD activity, and mutations in the Sec7 and PH domains, or deletion of the PH or CC domains inhibited the effects of insulin. Conclusions Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor.

  4. Defective insulin secretion by chronic glucagon receptor activation in glucose intolerant mice.

    Science.gov (United States)

    Ahlkvist, Linda; Omar, Bilal; Valeur, Anders; Fosgerau, Keld; Ahrén, Bo

    2016-03-01

    Stimulation of insulin secretion by short-term glucagon receptor (GCGR) activation is well characterized; however, the effect of long-term GCGR activation on β-cell function is not known, but of interest, since hyperglucagonemia occurs early during development of type 2 diabetes. Therefore, we examined whether chronic GCGR activation affects insulin secretion in glucose intolerant mice. To induce chronic GCGR activation, high-fat diet fed mice were continuously (2 weeks) infused with the stable glucagon analog ZP-GA-1 and challenged with oral glucose and intravenous glucose±glucagon-like peptide 1 (GLP1). Islets were isolated to evaluate the insulin secretory response to glucose±GLP1 and their pancreas were collected for immunohistochemical analysis. Two weeks of ZP-GA-1 infusion reduced insulin secretion both after oral and intravenous glucose challenges in vivo and in isolated islets. These inhibitory effects were corrected for by GLP1. Also, we observed increased β-cell area and islet size. We conclude that induction of chronic ZP-GA-1 levels in glucose intolerant mice markedly reduces insulin secretion, and thus, we suggest that chronic activation of the GCGR may contribute to the failure of β-cell function during development of type 2 diabetes.

  5. Insulin resistance in non-obese subjects is associated with activation of the JNK pathway and impaired insulin signaling in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Umesh B Masharani

    Full Text Available BACKGROUND: The pathogenesis of insulin resistance in the absence of obesity is unknown. In obesity, multiple stress kinases have been identified that impair the insulin signaling pathway via serine phosphorylation of key second messenger proteins. These stress kinases are activated through various mechanisms related to lipid oversupply locally in insulin target tissues and in various adipose depots. METHODOLOGY/PRINCIPAL FINDINGS: To explore whether specific stress kinases that have been implicated in the insulin resistance of obesity are potentially contributing to insulin resistance in non-obese individuals, twenty healthy, non-obese, normoglycemic subjects identified as insulin sensitive or resistant were studied. Vastus lateralis muscle biopsies obtained during euglycemic, hyperinsulinemic clamp were evaluated for insulin signaling and for activation of stress kinase pathways. Total and regional adipose stores and intramyocellular lipids (IMCL were assessed by DXA, MRI and (1H-MRS. In muscle of resistant subjects, phosphorylation of JNK was increased (1.36±0.23 vs. 0.78±0.10 OD units, P<0.05, while there was no evidence for activation of p38 MAPK or IKKβ. IRS-1 serine phosphorylation was increased (1.30±0.09 vs. 0.22±0.03 OD units, P<0.005 while insulin-stimulated tyrosine phosphorylation decreased (10.97±0.95 vs. 0.89±0.50 OD units, P<0.005. IMCL levels were twice as high in insulin resistant subjects (3.26±0.48 vs. 1.58±0.35% H(2O peak, P<0.05, who also displayed increased total fat and abdominal fat when compared to insulin sensitive controls. CONCLUSIONS: This is the first report demonstrating that insulin resistance in non-obese, normoglycemic subjects is associated with activation of the JNK pathway related to increased IMCL and higher total body and abdominal adipose stores. While JNK activation is consistent with a primary impact of muscle lipid accumulation on metabolic stress, further work is necessary to determine the

  6. Central Insulin Action Activates Kupffer Cells by Suppressing Hepatic Vagal Activation via the Nicotinic Alpha 7 Acetylcholine Receptor

    Directory of Open Access Journals (Sweden)

    Kumi Kimura

    2016-03-01

    Full Text Available Central insulin action activates hepatic IL-6/STAT3 signaling, which suppresses the gene expression of hepatic gluconeogenic enzymes. The vagus nerve plays an important role in this centrally mediated hepatic response; however, the precise mechanism underlying this brain-liver interaction is unclear. Here, we present our findings that the vagus nerve suppresses hepatic IL-6/STAT3 signaling via α7-nicotinic acetylcholine receptors (α7-nAchR on Kupffer cells, and that central insulin action activates hepatic IL-6/STAT3 signaling by suppressing vagal activity. Indeed, central insulin-mediated hepatic IL-6/STAT3 activation and gluconeogenic gene suppression were impeded in mice with hepatic vagotomy, pharmacological cholinergic blockade, or α7-nAchR deficiency. In high-fat diet-induced obese and insulin-resistant mice, control of the vagus nerve by central insulin action was disturbed, inducing a persistent increase of inflammatory cytokines. These findings suggest that dysregulation of the α7-nAchR-mediated control of Kupffer cells by central insulin action may affect the pathogenesis of chronic hepatic inflammation in obesity.

  7. Potentiation of insulin release in response to amino acid methyl esters correlates to activation of islet glutamate dehydrogenase activity

    DEFF Research Database (Denmark)

    Kofod, Hans; Lernmark, A; Hedeskov, C J

    1986-01-01

    Column perifusion of mouse pancreatic islets was used to study the ability of amino acids and their methyl esters to influence insulin release and activate islet glutamate dehydrogenase activity. In the absence of L-glutamine, L-serine and the methyl ester of L-phenylalanine, but neither L...... glutamate dehydrogenase activity showed that only the two methyl esters of L-phenylalanine and L-serine activated the enzyme. It is concluded that the mechanism by which methyl esters of amino acids potentiate insulin release is most likely to be mediated by the activation of pancreatic beta-cell glutamate...

  8. Prevention of COPD exacerbations

    DEFF Research Database (Denmark)

    Vestbo, Jørgen; Lange, Peter

    2015-01-01

    Exacerbations have significant impact on the morbidity and mortality of patients with chronic obstructive pulmonary disease. Most guidelines emphasise prevention of exacerbations by treatment with long-acting bronchodilators and/or anti-inflammatory drugs. Whereas most of this treatment is evidence......-based, it is clear that patients differ regarding the nature of exacerbations and are likely to benefit differently from different types of treatment. In this short review, we wish to highlight this, suggest a first step in differentiating pharmacological exacerbation prevention and call for more studies...... in this area. Finally, we wish to highlight that there are perhaps easier ways of achieving similar success in exacerbation prevention using nonpharmacological tools....

  9. Regular exercise enhances insulin activation of IRS-1-associated PI3-kinase in human skeletal muscle.

    Science.gov (United States)

    Kirwan, J P; del Aguila, L F; Hernandez, J M; Williamson, D L; O'Gorman, D J; Lewis, R; Krishnan, R K

    2000-02-01

    Insulin action in skeletal muscle is enhanced by regular exercise. Whether insulin signaling in human skeletal muscle is affected by habitual exercise is not well understood. Phosphatidylinositol 3-kinase (PI3-kinase) activation is an important step in the insulin-signaling pathway and appears to regulate glucose metabolism via GLUT-4 translocation in skeletal muscle. To examine the effects of regular exercise on PI3-kinase activation, 2-h hyperinsulinemic (40 mU. m(-2). min(-1))-euglycemic (5.0 mM) clamps were performed on eight healthy exercise-trained [24 +/- 1 yr, 71.8 +/- 2.0 kg, maximal O(2) uptake (VO(2 max)) of 56.1 +/- 2.5 ml. kg(-1). min(-1)] and eight healthy sedentary men and women (24 +/- 1 yr, 64.7 +/- 4.4 kg, VO(2 max) of 44.4 +/- 2.7 ml. kg(-1). min(-1)). A [6, 6-(2)H]glucose tracer was used to measure hepatic glucose output. A muscle biopsy was obtained from the vastus lateralis muscle at basal and at 2 h of hyperinsulinemia to measure insulin receptor substrate-1(IRS-1)-associated PI3-kinase activation. Insulin concentrations during hyperinsulinemia were similar for both groups (293 +/- 22 and 311 +/- 22 pM for trained and sedentary, respectively). Insulin-mediated glucose disposal rates (GDR) were greater (P exercise-trained compared with the sedentary control group (9.22 +/- 0.95 vs. 6.36 +/- 0.57 mg. kg fat-free mass(-1). min(-1)). Insulin-stimulated PI3-kinase activation was also greater (P < 0.004) in the trained compared with the sedentary group (3.8 +/- 0.5- vs. 1.8 +/- 0.2-fold increase from basal). Endurance capacity (VO(2 max)) was positively correlated with PI3-kinase activation (r = 0.53, P < 0.04). There was no correlation between PI3-kinase and muscle morphology. However, increases in GDR were positively related to PI3-kinase activation (r = 0.60, P < 0.02). We conclude that regular exercise leads to greater insulin-stimulated IRS-1-associated PI3-kinase activation in human skeletal muscle, thus facilitating enhanced insulin

  10. The road to the first, fully active and more stable human insulin variant with an additional disulfide bond

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Kjeldsen, Thomas B.; Jensen, Knud Jørgen

    2015-01-01

    addressed the question whether a human insulin variant with four disulfide bonds could exist and be fully functional. In this review, we give an overview of the road to engineering four-disulfide bonded insulin analogs. During our journey, we discovered several active four disulfide bonded insulin analogs...... with markedly improved stability and gained insights into the instability of analogs with seven cysteine residues, importance of dimerization for stability, insulin fibril formation process, and the conformation of insulin binding to its receptor. Our results also open the way for new strategies...

  11. Adiponectin increases glucose-induced insulin secretion through the activation of lipid oxidation.

    Science.gov (United States)

    Patané, G; Caporarello, N; Marchetti, P; Parrino, C; Sudano, D; Marselli, L; Vigneri, R; Frittitta, L

    2013-12-01

    The expression of adiponectin receptors has been demonstrated in human and rat pancreatic beta cells, where globular (g) adiponectin rescues rat beta cells from cytokine and fatty acid-induced apoptosis. The aim of our study was to evaluate whether adiponectin has a direct effect on insulin secretion and the metabolic pathways involved. Purified human pancreatic islets and rat beta cells (INS-1E) were exposed (1 h) to g-adiponectin, and glucose-induced insulin secretion was measured. A significant increase in glucose-induced insulin secretion was observed in the presence of g-adiponectin (1 nmol/l) with respect to control cells in both human pancreatic islets (n = 5, p < 0.05) and INS-1E cells (n = 5, p < 0.001). The effect of globular adiponectin on insulin secretion was independent of AMP-dependent protein kinase (AMPK) activation or glucose oxidation. In contrast, g-adiponectin significantly increased oleate oxidation (n = 5, p < 0.05), and the effect of g-adiponectin (p < 0.001) on insulin secretion by INS-1E was significantly reduced in the presence of etomoxir (1 μmol/l), an inhibitor of fatty acid beta oxidation. g-Adiponectin potentiates glucose-induced insulin secretion in both human pancreatic islets and rat beta cells via an AMPK independent pathway. Increased fatty acid oxidation rather than augmented glucose oxidation is the mechanism responsible. Overall, our data indicate that, in addition to its anti-apoptotic action, g-adiponectin has another direct effect on beta cells by potentiating insulin secretion. Adiponectin, therefore, in addition to its well-known effect on insulin sensitivity, has important effects at the pancreatic level.

  12. Effects of insulin and actin on phosphofructokinase activity and cellular distribution in skeletal muscle

    Directory of Open Access Journals (Sweden)

    Silva Ana Paula P.

    2004-01-01

    Full Text Available In this work, we report evidences that the association of phosphofructokinase and F-actin can be affected by insulin stimulation in rabbit skeletal muscle homogenates and that this association can be a mechanism of phos-phofructokinase regulation. Through co-sedimentation techniques, we observed that on insulin-stimulated tissues, approximately 70% of phosphofructokinase activity is co-located in an actin-enriched fraction, against 28% in control. This phenomenon is accompanied by a 100% increase in specific phosphofructokinase activity in stimulated homogenates. Purified F-actin causes an increase of 230% in phosphofructokinase activity and alters its kinetic parameters. The presence of F-actin increases the affinity of phosphofructokinase for fructose 6-phosphate nevertheless, with no changes in maximum velocity (Vmax. Here we propose that the modulation of cellular distribution of phosphofructokinase may be one of the mechanisms of control of glycolytic flux in mammalian muscle by insulin.

  13. ANTIDIABETIC AND HYPOLIPIDEMIC ACTIVITY OF GYMNEMA SYLVESTRE IN DEXAMETHASONE INDUCED INSULIN RESISTANCE IN ALBINO RATS

    Directory of Open Access Journals (Sweden)

    Hemanth Kumar V, Nagendra Nayak IM , Shobha V Huilgol, Saeed M Yendigeri , Narendar K

    2015-07-01

    Full Text Available Background: Gymnema sylvestre plant was widely used for medicinal purpose. The plant leaves were traditionally used to treat diabetes. Aim: To determine the antidiabetic and hypolipidemic activity of Gymnema sylvestre in dexamethasone induced insulin resistance in Albino rats. Objectives: The present study was undertaken to evaluate antidiabetic and hypolipidemic activity of Gymnema sylvestre leaf aqueous extract against dexamethasone induced insulin resistance in Albino rats. Materials and Methods: Animals were divided into five groups. Normal control and diabetic control group received gum acacia (2% orally for 12days, and normal saline (i.p., dexamethasone (8mg/kg/i.p. from day 7- day12 respectively. Two test groups (Gymnema sylvestre leaf aqueous extract 2 and 4gm/kg/p.o./12days and standard control received metformin (2gm/kg/p.o./12 days. The two test groups, standard control group received dexamethasone (8mg/kg/i.p from day 7- day 12 respectively. The antidiabetic and hypolipidemic activity was estimated by measuring serum glucose, insulin, lipid levels and histopathological evaluation of liver tissue. Results were analyzed by using one way ANOVA followed by Scheffe’s multiple comparison test. Results: Treatment with aqueous extract of Gymnema sylvestre (2 and 4gm/kg/p.o significantly (p<0.01 altered the elevated glucose, lipid, insulin levels and also improved the histopathology of liver in dexamethasone induced insulin resistance rats. Conclusion: Treatment with aqueous extract of Gymnema sylvestre improved the altered glucose, insulin and lipid profile in insulin resistance rats.

  14. Interleukin-18 activates skeletal muscle AMPK and reduces weight gain and insulin resistance in mice

    DEFF Research Database (Denmark)

    Madsen, Birgitte Lindegaard; Matthews, Vance B; Brandt, Claus

    2013-01-01

    Circulating interleukin (IL)-18 is elevated in obesity, but paradoxically causes hypophagia. We hypothesized that IL-18 may attenuate high fat diet induced insulin resistance by activating AMP activated protein kinase (AMPK). We studied mice with a global deletion of the α isoform of the IL-18...

  15. Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

    Directory of Open Access Journals (Sweden)

    Cecilia Prata

    2017-01-01

    Full Text Available Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

  16. Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

    Science.gov (United States)

    Prata, Cecilia; Zambonin, Laura; Rizzo, Benedetta; Vieceli Dalla Sega, Francesco

    2017-01-01

    Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

  17. Insulin signaling regulates fatty acid catabolism at the level of CoA activation.

    Directory of Open Access Journals (Sweden)

    Xiaojun Xu

    2012-01-01

    Full Text Available The insulin/IGF signaling pathway is a highly conserved regulator of metabolism in flies and mammals, regulating multiple physiological functions including lipid metabolism. Although insulin signaling is known to regulate the activity of a number of enzymes in metabolic pathways, a comprehensive understanding of how the insulin signaling pathway regulates metabolic pathways is still lacking. Accepted knowledge suggests the key regulated step in triglyceride (TAG catabolism is the release of fatty acids from TAG via the action of lipases. We show here that an additional, important regulated step is the activation of fatty acids for beta-oxidation via Acyl Co-A synthetases (ACS. We identify pudgy as an ACS that is transcriptionally regulated by direct FOXO action in Drosophila. Increasing or reducing pudgy expression in vivo causes a decrease or increase in organismal TAG levels respectively, indicating that pudgy expression levels are important for proper lipid homeostasis. We show that multiple ACSs are also transcriptionally regulated by insulin signaling in mammalian cells. In sum, we identify fatty acid activation onto CoA as an important, regulated step in triglyceride catabolism, and we identify a mechanistic link through which insulin regulates lipid homeostasis.

  18. Complement activation capacity in plasma before and during high-dose prednisolone treatment and tapering in exacerbations of Crohn's disease and ulcerative colitis

    Directory of Open Access Journals (Sweden)

    Baatrup Gunnar

    2005-09-01

    Full Text Available Abstract Background Ulcerative colitis (UC and Crohn's disease (CD are characterized by intestinal inflammation mainly caused by a disturbance in the balance between cytokines and increased complement (C activation. Our aim was to evaluate possible associations between C activation capacity and prednisolone treatment. Methods Plasma from patients with exacerbations of UC (n = 18 or CD (n = 18 were collected before and during high dose prednisolone treatment (1 mg/kg body weight and tapering. Friedman's two way analysis of variance, Mann-Whitney U test and Wilcoxon signed-rank sum test were used Results Before treatment, plasma from CD patients showed significant elevations in all C-mediated analyses compared to the values obtained from 38 healthy controls (p Conclusion Our findings indicate that C activation capacity is up-regulated significantly in plasma from CD patients. The decreases observed after prednisolone treatment reflect a general down-regulation in immune activation.

  19. Calorie restriction minimizes activation of insulin signaling in response to glucose: potential involvement of the growth hormone-insulin-like growth factor 1 axis.

    Science.gov (United States)

    Hayashi, Hiroko; Yamaza, Haruyoshi; Komatsu, Toshimitsu; Park, Seongjoon; Chiba, Takuya; Higami, Yoshikazu; Nagayasu, Takeshi; Shimokawa, Isao

    2008-09-01

    Calorie restriction (CR) may modulate insulin signaling in response to energy intake through suppression of the growth hormone (GH)-IGF-1 axis. We investigated the glucose-stimulated serum insulin response and subsequent alterations in insulin receptor (IR), Akt, and FoxO1 in the rat liver and quadriceps femoris muscle (QFM). Nine-month-old wild-type (W) male Wistar rats fed ad libitum (AL) or a 30% CR diet initiated at 6 weeks of age and GH-suppressed transgenic (Tg) rats fed AL were killed 15 min after intraperitoneal injection of glucose or saline. In W-AL rats, the serum insulin concentration was elevated by glucose injection. Concomitantly, the phosphorylated (p)-IR and p-Akt levels were increased in both tissues. The active FoxO1 level was decreased in the liver, but not significantly in the QFM. In W-CR and Tg-AL rats, the serum insulin response was lower, and no significant changes were noted for the p-IR, p-Akt, or active FoxO1 levels in the liver. In the QFM, the p-Akt level was increased in W-CR and Tg-AL rats with an insignificant elevation of p-IR levels. The phenotypic similarity of W-CR and Tg-AL rats suggest that CR minimizes activation of insulin signaling in response to energy intake mostly through the GH-IGF-1 axis.

  20. Structural insights into ligand-induced activation of the insulin receptor

    Energy Technology Data Exchange (ETDEWEB)

    Ward, C.; Lawrence, M.; Streltsov, V.; Garrett, T.; McKern, N.; Lou, M.-Z.; Lovrecz, G.; Adams, T. (CSIRO); (WEHIMR)

    2008-04-29

    The current model for insulin binding to the insulin receptor proposes that there are two binding sites, referred to as sites 1 and 2, on each monomer in the receptor homodimer and two binding surfaces on insulin, one involving residues predominantly from the dimerization face of insulin (the classical binding surface) and the other residues from the hexamerization face. High-affinity binding involves one insulin molecule using its two surfaces to make bridging contacts with site 1 from one receptor monomer and site 2 from the other. Whilst the receptor dimer has two identical site 1-site 2 pairs, insulin molecules cannot bridge both pairs simultaneously. Our structures of the insulin receptor (IR) ectodomain dimer and the L1-CR-L2 fragments of IR and insulin-like growth factor receptor (IGF-1R) explain many of the features of ligand-receptor binding and allow the two binding sites on the receptor to be described. The IR dimer has an unexpected folded-over conformation which places the C-terminal surface of the first fibronectin-III domain in close juxtaposition to the known L1 domain ligand-binding surface suggesting that the C-terminal surface of FnIII-1 is the second binding site involved in high-affinity binding. This is very different from previous models based on three-dimensional reconstruction from scanning transmission electron micrographs. Our single-molecule images indicate that IGF-1R has a morphology similar to that of IR. In addition, the structures of the first three domains (L1-CR-L2) of the IR and IGF-1R show that there are major differences in the two regions governing ligand specificity. The implications of these findings for ligand-induced receptor activation will be discussed. This review summarizes the key findings regarding the discovery and characterization of the insulin receptor, the identification and arrangement of its structural domains in the sequence and the key features associated with ligand binding. The remainder of the review

  1. The Proton-Activated Receptor GPR4 Modulates Glucose Homeostasis by Increasing Insulin Sensitivity

    Directory of Open Access Journals (Sweden)

    Luca Giudici

    2013-11-01

    Full Text Available Background: The proton-activated G protein-coupled receptor GPR4 is expressed in many tissues including white adipose tissue. GPR4 is activated by extracellular protons in the physiological pH range (i.e. pH 7.7 - 6.8 and is coupled to the production of cAMP. Methods: We examined mice lacking GPR4 and examined glucose tolerance and insulin sensitivity in young and aged mice as well as in mice fed with a high fat diet. Expression profiles of pro- and anti-inflammatory cytokines in white adipose tissue, liver and skeletal muscle was assessed. Results: Here we show that mice lacking GPR4 have an improved intraperitoneal glucose tolerance test and increased insulin sensitivity. Insulin levels were comparable but leptin levels were increased in GPR4 KO mice. Gpr4-/- showed altered expression of PPARα, IL-6, IL-10, TNFα, and TGF-1β in skeletal muscle, white adipose tissue, and liver. High fat diet abolished the differences in glucose tolerance and insulin sensitivity between Gpr4+/+ and Gpr4-/- mice. In contrast, in aged mice (12 months old, the positive effect of GPR4 deficiency on glucose tolerance and insulin sensitivity was maintained. Liver and adipose tissue showed no major differences in the mRNA expression of pro- and anti-inflammatory factors between aged mice of both genotypes. Conclusion: Thus, GPR4 deficiency improves glucose tolerance and insulin sensitivity. The effect may involve an altered balance between pro- and anti-inflammatory factors in insulin target tissues.

  2. Insulin Activates RSK (p90 Ribosomal S6 Kinase) to Trigger a New Negative Feedback Loop That Regulates Insulin Signaling for Glucose Metabolism*

    Science.gov (United States)

    Smadja-Lamère, Nicolas; Shum, Michael; Déléris, Paul; Roux, Philippe P.; Abe, Jun-Ichi; Marette, André

    2013-01-01

    We previously demonstrated that the mTORC1/S6K1 pathway is activated by insulin and nutrient overload (e.g. amino acids (AA)), which leads to the inhibition of the PI3K/Akt pathway via the inhibitory serine phosphorylation of IRS-1, notably on serine 1101 (Ser-1101). However, even in the absence of AA, insulin can still promote IRS-1 Ser-1101 phosphorylation by other kinases that remain to be fully characterized. Here, we describe a new negative regulator of IRS-1, the p90 ribosomal S6 kinase (RSK). Computational analyses revealed that Ser-1101 within IRS-1 falls into the consensus motif of RSK. Moreover, recombinant RSK phosphorylated IRS-1 C-terminal fragment on Ser-1101, which was prevented by mutations of this site or when a kinase-inactive mutant of RSK was used. Using antibodies directed toward the phosphorylation sites located in the activation segment of RSK (Ser-221 or Ser-380), we found that insulin activates RSK in L6 myocytes in the absence of AA overload. Inhibition of RSK using either the pharmacological inhibitor BI-D1870 or after adenoviral expression of a dominant negative RSK1 mutant (RSK1-DN) showed that RSK selectively phosphorylates IRS-1 on Ser-1101. Accordingly, expression of the RSK1-DN mutant in L6 myocytes and FAO hepatic cells improved insulin action on glucose uptake and glucose production, respectively. Furthermore, RSK1 inhibition prevented insulin resistance in L6 myocytes chronically exposed to high glucose and high insulin. These results show that RSK is a novel regulator of insulin signaling and glucose metabolism and a potential mediator of insulin resistance, notably through the negative phosphorylation of IRS-1 on Ser-1101. PMID:24036112

  3. Dietary fat and insulin resistance: a connection through leptin and PPARγ activation

    Directory of Open Access Journals (Sweden)

    Doaa Nader Al-Jada

    2016-06-01

    Full Text Available Insulin resistance refers to reduced insulin action in peripheral tissues and impaired suppression of endogenous glucose production, a state which is critical for maintaining normal glucose homeostasis. Insulin resistance is partly explained by genetic factors and is strongly influenced by the individual's habitual lifestyle. Investigating factors that may influence the development of insulin resistance and their mechanisms of action is highly significant; one of these factors include dietary fat. Both quantitative and qualitative terms of dietary fat have been known to play an important role in the development of insulin resistance, although the mechanism underlying this effect is not fully understood. In this regard, the classical view has been that dietary fat quality mainly affects cell membrane fatty acid composition and consequently the membrane function. Recently, the relationship between dietary fat and insulin resistance has entered an advanced level due to the discovery that different fatty acids can regulate gene expression, transcriptional activity and adipocytokines secretion. In essence, this provides new mechanisms by which fatty acids exert their cellular effects. The present review critically assesses the effect of dietary fat quality on the development of insulin resistance in relation to the adipocytokine, leptin and the activation of the transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ. It is evident that fat quality influences the development of insulin resistance and has a more important role than quantity. Leptin and PPARγ prove to be potential candidates linking dietary fat with insulin resistance. However, the exact role or mechanism of action of various types of dietary fat in the development of insulin resistance is still uncertain. Further well-controlled studies in humans are necessary to establish better evidence-based dietary fat recommendations for diabetes prevention and its

  4. Human insulin production from a novel mini-proinsulin which has high receptor-binding activity.

    Science.gov (United States)

    Chang, S G; Kim, D Y; Choi, K D; Shin, J M; Shin, H C

    1998-02-01

    To increase the folding efficiency of the insulin precursor and the production yield of insulin, we have designed a mini-proinsulin (M2PI) having the central C-peptide region replaced with a sequence forming a reverse turn. The mini-proinsulin was fused at the N-terminus to a 21-residue fusion partner containing a His10 tag for affinity purification. The gene for the fusion protein was inserted downstream of the T7 promoter of the expression plasmid pET-3a, and the fusion proteins were produced as inclusion bodies in the Escherichia coli cytoplasm at levels up to 25% of the total cell protein. The protein was sulphonated, cleaved by CNBr and the M2PI mini-proinsulin was purified using ion-exchange chromatography. The refolding yield of M2PI was 20-40% better than that of proinsulin studied at the same molar concentrations, indicating that the short turn-forming sequence is more effective in the refolding process than the much longer C-peptide. Native human insulin was successfully generated by subsequent enzymic conversion of mini-proinsulin. The mini-proinsulin exhibited high receptor-binding activity, about 50% as potent as insulin, suggesting that this single-chained mini-proinsulin may provide a foundation in understanding the receptor-bound structure of insulin as well as the role of C-peptide in the folding and activity of proinsulin.

  5. Independent Benefits of Meeting the 2008 Physical Activity Guidelines to Insulin Resistance in Obese Latino Children

    Directory of Open Access Journals (Sweden)

    Nazrat Mirza

    2012-01-01

    Full Text Available We examined the independent association between moderate-to-vigorous physical activity (MVPA and insulin resistance (IR among obese Latino children (N=113; 7–15 years who were enrolled in a community-based obesity intervention. Baseline information on physical activity was gathered by self-report. Clinical assessments of body composition, resting energy expenditure (REE, as well as glucose and insulin responses to an oral glucose tolerance test (OGTT were performed after an overnight fast. Insulin resistance was defined as a 2 h insulin concentration >57 μU·mL-1. We observed that those obese children who met the 2008 Guidelines for MVPA (≥60 min/day experienced a significantly lower odds of IR compared with those not meeting the Guidelines (OR=0.29; 95% CI: (0.10–0.92 and these findings were independent of age, sex, pubertal stage, acculturation, fasting insulin, and 2 h glucose concentrations. Efforts to promote 60 min or more of daily MVPA among children from ethnic minority and high-risk communities should assume primary public health importance.

  6. AMPK activation restores the stimulation of glucose uptake in an in vitro model of insulin-resistant cardiomyocytes via the activation of protein kinase B.

    Science.gov (United States)

    Bertrand, Luc; Ginion, Audrey; Beauloye, Christophe; Hebert, Alexandre D; Guigas, Bruno; Hue, Louis; Vanoverschelde, Jean-Louis

    2006-07-01

    Diabetic hearts are known to be more susceptible to ischemic disease. Biguanides, like metformin, are known antidiabetic drugs that lower blood glucose concentrations by decreasing hepatic glucose production and increasing glucose disposal in muscle. Part of these metabolic effects is thought to be mediated by the activation of AMP-activated protein kinase (AMPK). In this work, we studied the relationship between AMPK activation and glucose uptake stimulation by biguanides and oligomycin, another AMPK activator, in both insulin-sensitive and insulin-resistant cardiomyocytes. In insulin-sensitive cardiomyocytes, insulin, biguanides and oligomycin were able to stimulate glucose uptake with the same efficiency. Stimulation of glucose uptake by insulin or biguanides was correlated to protein kinase B (PKB) or AMPK activation, respectively, and were additive. In insulin-resistant cardiomyocytes, where insulin stimulation of glucose uptake was greatly reduced, biguanides or oligomycin, in the absence of insulin, induced a higher stimulation of glucose uptake than that obtained in insulin-sensitive cells. This stimulation was correlated with the activation of both AMPK and PKB and was sensitive to the phosphatidylinositol-3-kinase/PKB pathway inhibitors. Finally, an adenoviral-mediated expression of a constitutively active form of AMPK increased both PKB phosphorylation and glucose uptake in insulin-resistant cardiomyocytes. We concluded that AMPK activators, like biguanides and oligomycin, are able to restore glucose uptake stimulation, in the absence of insulin, in insulin-resistant cardiomyocytes via the additive activation of AMPK and PKB. Our results suggest that AMPK activation could restore normal glucose metabolism in diabetic hearts and could be a potential therapeutic approach to treat insulin resistance.

  7. Hepatic Insulin Resistance Following Chronic Activation of the CREB Coactivator CRTC2*

    Science.gov (United States)

    Hogan, Meghan F.; Ravnskjaer, Kim; Matsumura, Shigenobu; Huising, Mark O.; Hull, Rebecca L.; Kahn, Steven E.; Montminy, Marc

    2015-01-01

    Under fasting conditions, increases in circulating concentrations of glucagon maintain glucose homeostasis via the induction of hepatic gluconeogenesis. Triggering of the cAMP pathway in hepatocytes stimulates the gluconeogenic program via the PKA-mediated phosphorylation of CREB and dephosphorylation of the cAMP-regulated CREB coactivators CRTC2 and CRTC3. In parallel, decreases in circulating insulin also increase gluconeogenic gene expression via the de-phosphorylation and activation of the forkhead transcription factor FOXO1. Hepatic gluconeogenesis is increased in insulin resistance where it contributes to the attendant hyperglycemia. Whether selective activation of the hepatic CREB/CRTC pathway is sufficient to trigger metabolic changes in other tissues is unclear, however. Modest hepatic expression of a phosphorylation-defective and therefore constitutively active CRTC2S171,275A protein increased gluconeogenic gene expression under fasting as well as feeding conditions. Circulating glucose concentrations were constitutively elevated in CRTC2S171,275A-expressing mice, leading to compensatory increases in circulating insulin concentrations that enhance FOXO1 phosphorylation. Despite accompanying decreases in FOXO1 activity, hepatic gluconeogenic gene expression remained elevated in CRTC2S171,275A mice, demonstrating that chronic increases in CRTC2 activity in the liver are indeed sufficient to promote hepatic insulin resistance and to disrupt glucose homeostasis. PMID:26342077

  8. Hepatic Insulin Resistance Following Chronic Activation of the CREB Coactivator CRTC2.

    Science.gov (United States)

    Hogan, Meghan F; Ravnskjaer, Kim; Matsumura, Shigenobu; Huising, Mark O; Hull, Rebecca L; Kahn, Steven E; Montminy, Marc

    2015-10-23

    Under fasting conditions, increases in circulating concentrations of glucagon maintain glucose homeostasis via the induction of hepatic gluconeogenesis. Triggering of the cAMP pathway in hepatocytes stimulates the gluconeogenic program via the PKA-mediated phosphorylation of CREB and dephosphorylation of the cAMP-regulated CREB coactivators CRTC2 and CRTC3. In parallel, decreases in circulating insulin also increase gluconeogenic gene expression via the de-phosphorylation and activation of the forkhead transcription factor FOXO1. Hepatic gluconeogenesis is increased in insulin resistance where it contributes to the attendant hyperglycemia. Whether selective activation of the hepatic CREB/CRTC pathway is sufficient to trigger metabolic changes in other tissues is unclear, however. Modest hepatic expression of a phosphorylation-defective and therefore constitutively active CRTC2S171,275A protein increased gluconeogenic gene expression under fasting as well as feeding conditions. Circulating glucose concentrations were constitutively elevated in CRTC2S171,275A-expressing mice, leading to compensatory increases in circulating insulin concentrations that enhance FOXO1 phosphorylation. Despite accompanying decreases in FOXO1 activity, hepatic gluconeogenic gene expression remained elevated in CRTC2S171,275A mice, demonstrating that chronic increases in CRTC2 activity in the liver are indeed sufficient to promote hepatic insulin resistance and to disrupt glucose homeostasis.

  9. Covalent glycoinositolphospholipid (GPI binding to hemoglobin is associated with insulin-activation of erythrocyte membrane protease

    Directory of Open Access Journals (Sweden)

    VESNA NIKETIC

    2004-05-01

    Full Text Available Recently, it was demonstrated that prolonged hyperinsulinism associated with hypoglycemia, both in vivo and in vitro, caused covalent glycoinositolphospholipid (GPI binding to the C termini of both hemoglobin b-chains, which resulted in the formation of a novel, hitherto unrecognized, minor hemoglobin fraction (GPI-Hb (Niketic et al., Biochem. Biophys. Res. Commun. 239 (1997 435. In this study it was demonstrated that exposure of erythrocyte membranes to insulin causes the activation of membrane protease as well as that the formation of GPI-Hb parallels its activity. It is suggested that the insulin-activated protease is able to catalyze, albeit slowly, the transpeptidation, i.e., the replacement of the carboxy-terminal amino acid(s residues of the Hb b-chains with GPI as an exogenous nucleophile. To our knowledge the present results show for the first time that insulin stimulates protease activity in erythrocyte membranes, as well as that insulin-activated protease may be involved in post-translational GPI binding to proteins.

  10. Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin.

    Science.gov (United States)

    Pruett, W; Yuan, Y; Rose, E; Batzer, A G; Harada, N; Skolnik, E Y

    1995-03-01

    Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context

  11. Acute exacerbation of COPD.

    Science.gov (United States)

    Ko, Fanny W; Chan, Ka Pang; Hui, David S; Goddard, John R; Shaw, Janet G; Reid, David W; Yang, Ian A

    2016-10-01

    The literature of acute exacerbation of chronic obstructive pulmonary disease (COPD) is fast expanding. This review focuses on several aspects of acute exacerbation of COPD (AECOPD) including epidemiology, diagnosis and management. COPD poses a major health and economic burden in the Asia-Pacific region, as it does worldwide. Triggering factors of AECOPD include infectious (bacteria and viruses) and environmental (air pollution and meteorological effect) factors. Disruption in the dynamic balance between the 'pathogens' (viral and bacterial) and the normal bacterial communities that constitute the lung microbiome likely contributes to the risk of exacerbations. The diagnostic approach to AECOPD varies based on the clinical setting and severity of the exacerbation. After history and examination, a number of investigations may be useful, including oximetry, sputum culture, chest X-ray and blood tests for inflammatory markers. Arterial blood gases should be considered in severe exacerbations, to characterize respiratory failure. Depending on the severity, the acute management of AECOPD involves use of bronchodilators, steroids, antibiotics, oxygen and noninvasive ventilation. Hospitalization may be required, for severe exacerbations. Nonpharmacological interventions including disease-specific self-management, pulmonary rehabilitation, early medical follow-up, home visits by respiratory health workers, integrated programmes and telehealth-assisted hospital at home have been studied during hospitalization and shortly after discharge in patients who have had a recent AECOPD. Pharmacological approaches to reducing risk of future exacerbations include long-acting bronchodilators, inhaled steroids, mucolytics, vaccinations and long-term macrolides. Further studies are needed to assess the cost-effectiveness of these interventions in preventing COPD exacerbations.

  12. The relationship between vitamin D status, physical activity and insulin resistance in overweight and obese subjects

    Directory of Open Access Journals (Sweden)

    Gülis Kavadar

    2015-05-01

    Full Text Available Type 2 diabetes mellitus (T2DM incidence has been increasing worldwide along with the rise of obesity and sedantery lifestyle. Decreased physical activity (PA and obesity have also been associated with the low vitamin D levels. We aimed to determine the association between PA, vitamin D status and insulin resistance in overweight and obese subjects. A total of 294 (186 female, 108 male overweight or obese subjects were included in this cross-sectional study. 25-hydroxy vitamin D (25(OHD, insulin, fasting plasma glucose (FPG and HbA1c levels were measured in blood samples. Body mass index (BMI, HOMA-index and total score of International Physical Activity Questionnaire-long form (IPAQ were calculated. Insulin resistant subjects were compared with the non-resistant group. The mean age of the participants was 45±12.25 and 41.39±10.32; 25(OHD levels were 8.91 ± 4.30 and 17.62 ± 10.47 ng/dL; BMIs were 31.29 ± 4.48  and 28.2 ± 3.16 kg/m², IPAQ total scores were 548.71±382.81 and 998±486.21 in the insulin resistant and nonresistant subjects, respectively. There was a statistically significant difference in terms of 25(OHD, FPG, insulin levels, IPAQ  total score and BMI between the two groups (p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.001.Significantly low 25(OHD levels, high BMI and low PA in insulin resistant subjects confirm the importance of active lifestyle and the maintenance of normal vitamin D levels in overweight and obese subjects in prevention of T2DM.

  13. Artemisia extracts activate PPARγ, promote adipogenesis, and enhance insulin sensitivity in adipose tissue of obese mice.

    Science.gov (United States)

    Richard, Allison J; Burris, Thomas P; Sanchez-Infantes, David; Wang, Yongjun; Ribnicky, David M; Stephens, Jacqueline M

    2014-01-01

    Studies have shown that the inability of adipose tissue to properly expand during the obese state or respond to insulin can lead to metabolic dysfunction. Artemisia is a diverse group of plants that has a history of medicinal use. The aim of this study was to examine the ability of ethanolic extracts of Artemisia scoparia (SCO) and Artemisia santolinifolia (SAN) to modulate adipocyte development in cultured adipocytes and white adipose tissue (WAT) function in vivo using a mouse model of diet-induced obesity. Adipogenesis was assessed using Oil Red O staining and immunoblotting. A nuclear receptor specificity assay was used to examine the specificity of SCO- and SAN-induced PPARγ activation. C57BL/6J mice, fed a high-fat diet, were gavaged with saline, SCO, or SAN for 2 wk. Whole-body insulin sensitivity was examined using insulin tolerance tests. WAT depots were assessed via immunoblotting for markers of insulin action and adipokine production. We established that SCO and SAN were highly specific activators of PPARγ and did not activate other nuclear receptors. After a 1-wk daily gavage, SCO- and SAN-treated mice had lower insulin-induced glucose disposal rates than control mice. At the end of the 2-wk treatment period, SCO- and SAN-treated mice had enhanced insulin-responsive Akt serine-473 phosphorylation and significantly decreased monocyte chemotactic protein-1 levels in visceral WAT compared with control mice; these differences were depot specific. Moreover, plasma adiponectin levels were increased following SCO treatment. Overall, these studies demonstrate that extracts from two Artemisia species can have metabolically favorable effects on adipocytes and WAT. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Activation of proteinase 3 contributes to nonalcoholic fatty liver disease and insulin resistance

    NARCIS (Netherlands)

    Toonen, Erik J.M.; Mirea, Andreea Manuela; Tack, Cees J.; Stienstra, Rinke; Ballak, Dov B.; Diepen, van Janna A.; Hijmans, Anneke; Chavakis, Triantafyllos; Dokter, Wim H.; Pham, Christine Tn; Netea, Mihai G.; Dinarello, Charles A.; Joosten, Leo A.B.

    2016-01-01

    Activation of inflammatory pathways is known to accompany development of obesity-induced nonalcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes. In addition to caspase-1, the neutrophil serine proteases proteinase 3, neutrophil elastase and cathepsin G are able to proces

  15. Structure based discovery of small molecules to regulate the activity of human insulin degrading enzyme.

    Directory of Open Access Journals (Sweden)

    Bilal Çakir

    Full Text Available BACKGROUND: Insulin-degrading enzyme (IDE is an allosteric Zn(+2 metalloprotease involved in the degradation of many peptides including amyloid-β, and insulin that play key roles in Alzheimer's disease (AD and type 2 diabetes mellitus (T2DM, respectively. Therefore, the use of therapeutic agents that regulate the activity of IDE would be a viable approach towards generating pharmaceutical treatments for these diseases. Crystal structure of IDE revealed that N-terminal has an exosite which is ∼30 Å away from the catalytic region and serves as a regulation site by orientation of the substrates of IDE to the catalytic site. It is possible to find small molecules that bind to the exosite of IDE and enhance its proteolytic activity towards different substrates. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we applied structure based drug design method combined with experimental methods to discover four novel molecules that enhance the activity of human IDE. The novel compounds, designated as D3, D4, D6, and D10 enhanced IDE mediated proteolysis of substrate V, insulin and amyloid-β, while enhanced degradation profiles were obtained towards substrate V and insulin in the presence of D10 only. CONCLUSION/SIGNIFICANCE: This paper describes the first examples of a computer-aided discovery of IDE regulators, showing that in vitro and in vivo activation of this important enzyme with small molecules is possible.

  16. Structure based discovery of small molecules to regulate the activity of human insulin degrading enzyme.

    Science.gov (United States)

    Çakir, Bilal; Dağliyan, Onur; Dağyildiz, Ezgi; Bariş, İbrahim; Kavakli, Ibrahim Halil; Kizilel, Seda; Türkay, Metin

    2012-01-01

    Insulin-degrading enzyme (IDE) is an allosteric Zn(+2) metalloprotease involved in the degradation of many peptides including amyloid-β, and insulin that play key roles in Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM), respectively. Therefore, the use of therapeutic agents that regulate the activity of IDE would be a viable approach towards generating pharmaceutical treatments for these diseases. Crystal structure of IDE revealed that N-terminal has an exosite which is ∼30 Å away from the catalytic region and serves as a regulation site by orientation of the substrates of IDE to the catalytic site. It is possible to find small molecules that bind to the exosite of IDE and enhance its proteolytic activity towards different substrates. In this study, we applied structure based drug design method combined with experimental methods to discover four novel molecules that enhance the activity of human IDE. The novel compounds, designated as D3, D4, D6, and D10 enhanced IDE mediated proteolysis of substrate V, insulin and amyloid-β, while enhanced degradation profiles were obtained towards substrate V and insulin in the presence of D10 only. This paper describes the first examples of a computer-aided discovery of IDE regulators, showing that in vitro and in vivo activation of this important enzyme with small molecules is possible.

  17. Dietary Fructose Activates Insulin Signaling and Inflammation in Adipose Tissue: Modulatory Role of Resveratrol.

    Science.gov (United States)

    Pektas, Mehmet Bilgehan; Koca, Halit Bugra; Sadi, Gokhan; Akar, Fatma

    2016-01-01

    The effects of high-fructose diet on adipose tissue insulin signaling and inflammatory process have been poorly documented. In this study, we examined the influences of long-term fructose intake and resveratrol supplementation on the expression of genes involved in insulin signaling and the levels of inflammatory cytokines and sex hormones in the white adipose tissues of male and female rats. Consumption of high-fructose diet for 24 weeks increased the expression of genes involved in insulin signaling including IR, IRS-1, IRS-2, Akt, PI3K, eNOS, mTOR, and PPARγ, despite induction of proinflammatory markers, iNOS, TNFα, IL-1β, IL-18, MDA, and ALT, as well as anti-inflammatory factors, IL-10 and Nrf2 in adipose tissues from males and females. Total and free testosterone concentrations of adipose tissues were impaired in males but increased in females, although there were no changes in their blood levels. Resveratrol supplementation markedly restored the levels of MDA, IL6, IL-10, and IL-18, as well as iNOS, Nrf2, and PI3K mRNA, in adipose tissues of both genders. Dietary fructose activates both insulin signaling and inflammatory pathway in the adipose tissues of male and female rats proposing no correlation between the tissue insulin signaling and inflammation. Resveratrol has partly modulatory effects on fructose-induced changes.

  18. Role of metabolically active hormones in the insulin resistance associated with short-term glucocorticoid treatment

    Directory of Open Access Journals (Sweden)

    Lip Gregory YH

    2006-09-01

    Full Text Available Abstract Background The mechanisms by which glucocorticoid therapy promotes obesity and insulin resistance are incompletely characterized. Modulations of the metabolically active hormones, tumour necrosis factor alpha (TNF alpha, ghrelin, leptin and adiponectin are all implicated in the development of these cardiovascular risk factors. Little is known about the effects of short-term glucocorticoid treatment on levels of these hormones. Research methods and procedures Using a blinded, placebo-controlled approach, we randomised 25 healthy men (mean (SD age: 24.2 (5.4 years to 5 days of treatment with either placebo or oral dexamethasone 3 mg twice daily. Fasting plasma TNFα, ghrelin, leptin and adiponectin were measured before and after treatment. Results Mean changes in all hormones were no different between treatment arms, despite dexamethasone-related increases in body weight, blood pressure, HDL cholesterol and insulin. Changes in calculated indices of insulin sensitivity (HOMA-S, insulin sensitivity index were strongly related to dexamethasone treatment (p Discussion Our data do not support a role for TNF alpha, ghrelin, leptin or adiponectin in the insulin resistance associated with short-term glucocorticoid treatment.

  19. Structure and dynamics of the insulin receptor: implications for receptor activation and drug discovery.

    Science.gov (United States)

    Ye, Libin; Maji, Suvrajit; Sanghera, Narinder; Gopalasingam, Piraveen; Gorbunov, Evgeniy; Tarasov, Sergey; Epstein, Oleg; Klein-Seetharaman, Judith

    2017-07-01

    Recently, major progress has been made in uncovering the mechanisms of how insulin engages its receptor and modulates downstream signal transduction. Here, we present in detail the current structural knowledge surrounding the individual components of the complex, binding sites, and dynamics during the activation process. A novel kinase triggering mechanism, the 'bow-arrow model', is proposed based on current knowledge and computational simulations of this system, in which insulin, after its initial interaction with binding site 1, engages with site 2 between the fibronectin type III (FnIII)-1 and -2 domains, which changes the conformation of FnIII-3 and eventually translates into structural changes across the membrane. This model provides a new perspective on the process of insulin binding to its receptor and, thus, could lead to future novel drug discovery efforts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Central Administration of Insulin and Leptin Together Enhance Renal Sympathetic Nerve Activity and Fos Production in the Arcuate Nucleus

    Science.gov (United States)

    Habeeballah, Hamza; Alsuhaymi, Naif; Stebbing, Martin J.; Jenkins, Trisha A.; Badoer, Emilio

    2017-01-01

    There is considerable interest in the central actions of insulin and leptin. Both induce sympatho-excitation. This study (i) investigated whether centrally administered leptin and insulin together elicits greater increases in renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP) and heart rate (HR) than when given alone, and (ii) quantified the number of activated neurons in brain regions influencing SNA, to identify potential central sites of interaction. In anesthetised (urethane 1.4–1.6 g/kg iv) male Sprague-Dawley rats, RSNA, MAP, and HR were recorded following intracerebroventricular (ICV) saline (control; n = 5), leptin (7 μg; n = 5), insulin (500 mU; n = 4) and the combination of leptin and insulin; (n = 4). Following leptin or insulin alone, RSNA was significantly increased (74 and 62% respectively). MAP responses were not significantly different between the groups. Insulin alone significantly increased HR. Leptin alone also increased HR but it was significantly less than following insulin alone (P < 0.005). When leptin and insulin were combined, the RSNA increase (124%) was significantly greater than the response to either alone. There were no differences between the groups in MAP responses, however, the increase in HR induced by insulin was attenuated by leptin. Of the brain regions examined, only in the arcuate nucleus did leptin and insulin together increase the number of Fos-positive cell nuclei significantly more than leptin or insulin alone. In the lamina terminalis and rostroventrolateral medulla, leptin and insulin together increased Fos, but the effect was not greater than leptin alone. The results suggest that when central leptin and insulin levels are elevated, the sympatho-excitatory response in RSNA will be greater. The arcuate nucleus may be a common site of cardiovascular integration. PMID:28119622

  1. Plasminogen activator inhibitor-1, free fatty acids, and insulin resistance in patients with myocardial infarction

    Directory of Open Access Journals (Sweden)

    Gruzdeva O

    2013-08-01

    Full Text Available Olga Gruzdeva, Evgenya Uchasova, Yulia Dyleva, Ekaterina Belik, Ekaterina Shurygina, Olga Barbarash Research Institute for Complex Issues of Cardiovascular Diseases under the Siberian Branch of the Russian Academy of Medical Sciences, Kemerovo, Russian Federation Background: Insulin resistance is known to be a common feature of type 2 diabetes mellitus and is regarded as an important mechanism in the pathogenesis of this disease. The key pathogenetic mechanisms of insulin resistance progression are free fatty acids metabolism impairment and enhanced activity of plasminogen activator inhibitor 1. Both free fatty acids and plasminogen activator inhibitor 1 are recognized as risk factors for coronary heart disease. Methods: The patients were divided into two groups: group 1 included 65 non-diabetic myocardial infarction patients and group 2 enrolled 60 diabetic myocardial infarction patients. The control group consisted of 30 sex- and age-matched volunteers. The concentration of serum free fatty acids, glucose, C-peptide, and insulin were measured on the 1st and 12th days of the study. All the patients had their postprandial glycemia, insulin, and C-peptide concentrations measured 2 hours after a standard carbohydrate breakfast containing 360 kcal (protein 20 g, carbohydrate 57 g, and fat 9 g. Results: Free fatty acids levels in group 1 and in group 2 exceeded the control group values by 7-fold and 11-fold, respectively. Plasminogen activator inhibitor 1 concentration was 2.5-fold higher in group 1 and 4.6-fold higher in group 2 compared to the control group on the 1st day from the myocardial infarction onset. In addition, plasminogen activator inhibitor 1 concentration was significantly reduced in both groups on the 12th day from the myocardial infarction onset; however, it did not achieve the control group values. Conclusion: Increased postprandial glucose level, insulinemia, and elevated levels of free fatty acids and plasminogen activator

  2. Strategies to enhance compliance to physical activity for patients with insulin resistance.

    Science.gov (United States)

    Kirk, Alison; De Feo, Pierpaolo

    2007-06-01

    The evidence that physical activity is an effective therapeutic tool in the management of insulin resistance and type 2 diabetes is well documented. Limited research has addressed how best to promote and maintain physical activity in these individuals. This paper explores strategies to enhance compliance to physical activity for patients with insulin resistance. Several evidence-based guidelines and reviews recommend that physical activity interventions are based on a valid theoretical framework. However, there is no evidence-based consensus on the best theory or the combination of theories to use. Motivational tools such as pedometers, wearable sensors measuring energy expenditure, and point of choice prompts appear to be effective at stimulating short-term substantial increases in physical activity, but further strategies to maintain physical activity behaviour change are required. Physical activity consultation has demonstrated effective physical activity promotion over periods of up to 2 years in people with type 2 diabetes. Future research should identify the longer term effects of this intervention and the effectiveness of different methods of delivery. Overall, there needs to be a lot more focus on this area of research. Without this, the abundance of research investigating the effects of physical activity on people with insulin resistance and type 2 diabetes is essentially redundant.

  3. Insulin receptor-overexpressing β-cells ameliorate hyperglycemia in diabetic rats through Wnt signaling activation.

    Directory of Open Access Journals (Sweden)

    Mi-Hyun Kim

    Full Text Available To investigate the therapeutic efficacy and mechanism of β-cells with insulin receptor (IR overexpression on diabetes mellitus (DM, rat insulinoma (INS-1 cells were engineered to stably express human insulin receptor (INS-IR cells, and subsequently transplanted into streptozotocin- induced diabetic rats. Compared with INS-1 cells, INS-IR cells showed improved β-cell function, including the increase in glucose utilization, calcium mobilization, and insulin secretion, and exhibited a higher rate of cell proliferation, and maintained lower levels of blood glucose in diabetic rats. These results were attributed to the increase of β-catenin/PPARγ complex bindings to peroxisome proliferator response elements in rat glucokinase (GK promoter and the prolongation of S-phase of cell cycle by cyclin D1. These events resulted from more rapid and higher phosphorylation levels of insulin-signaling intermediates, including insulin receptor substrate (IRS-1/IRS-2/phosphotylinositol 3 kinase/v-akt murine thymoma viral oncogene homolog (AKT 1, and the consequent enhancement of β-catenin nuclear translocation and Wnt responsive genes including GK and cyclin D1. Indeed, the higher functionality and proliferation shown in INS-IR cells were offset by β-catenin, cyclin D1, GK, AKT1, and IRS-2 gene depletion. In addition, the promotion of cell proliferation and insulin secretion by Wnt signaling activation was shown by 100 nM insulin treatment, and to a similar degree, was shown in INS-IR cells. In this regard, this study suggests that transferring INS-IR cells into diabetic animals is an effective and feasible DM treatment. Accordingly, the method might be a promising alternative strategy for treatment of DM given the adverse effects of insulin among patients, including the increased risk of modest weight gain and hypoglycemia. Additionally, this study demonstrates that the novel mechanism of cross-talk between insulin and Wnt signaling plays a primary role in

  4. Inhibition of M1 macrophage activation in adipose tissue by berberine improves insulin resistance.

    Science.gov (United States)

    Ye, Lifang; Liang, Shu; Guo, Chao; Yu, Xizhong; Zhao, Juan; Zhang, Hao; Shang, Wenbin

    2016-12-01

    Insulin resistance is associated with a chronic inflammation in adipose tissue which is propagated by a phenotypic switch in adipose tissue macrophage (ATM) polarization. This study aimed to investigate whether berberine, the major alkaloid of rhizoma coptidis, can improve insulin resistance through inhibiting ATM activation and inflammatory response in adipose tissue. High-fat-diet induced obese mice were administered oral with berberine (50mg/kg/day) for 14days. ATMs were analysed using FACS and insulin resistance was evaluated. Expressions of pro-inflammatory cytokines and activation of inflammatory pathways were detected. The chemotaxis of macrophages was measured. Glucose consumption and insulin signalling of adipocytes were examined. Berberine significantly decreased F4/80(+)/CD11c(+)/CD206(-) cells in the stromal vascular fraction from adipose tissue and improved glucose tolerance in obsess mice. In addition, berberine reduced the elevated levels of serum TNF-α, IL-6 and MCP-1 and the expressions of TNF-α, IL-6 and MCP-1 and attenuated the phosphorylation of JNK and IKKβ and the expression of NF-κB p65 in the obese adipose tissue, Raw264.7 macrophages and 3T3-L1 adipocytes, respectively. The phosphorylation of IRS-1 (Ser307) was inhibited by berberine in adipose tissue and cultured adipocytes. The phosphorylation of AKT (Ser473) was increased in berberine-treated adipose tissue. Conditioned medium from adipocytes treated with berberine reduced the number of infiltrated macrophages. Berberine partly restored the impaired glucose consumption and the activation of IRS-1 (Ser307) in adipocytes induced by the activation of macrophages. Our findings imply that berberine improves insulin resistance by inhibiting M1 macrophage activation in adipose tissue. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Essential role of PSM/SH2-B variants in insulin receptor catalytic activation and the resulting cellular responses.

    Science.gov (United States)

    Zhang, Manchao; Deng, Youping; Tandon, Ruchi; Bai, Cheng; Riedel, Heimo

    2008-01-01

    The positive regulatory role of PSM/SH2-B downstream of various mitogenic receptor tyrosine kinases or gene disruption experiments in mice support a role of PSM in the regulation of insulin action. Here, four alternative PSM splice variants and individual functional domains were compared for their role in the regulation of specific metabolic insulin responses. We found that individual PSM variants in 3T3-L1 adipocytes potentiated insulin-mediated glucose and amino acid transport, glycogenesis, lipogenesis, and key components in the metabolic insulin response including p70 S6 kinase, glycogen synthase, glycogen synthase kinase 3 (GSK3), Akt, Cbl, and IRS-1. Highest activity was consistently observed for PSM alpha, followed by beta, delta, and gamma with decreasing activity. In contrast, dominant-negative peptide mimetics of the PSM Pro-rich, pleckstrin homology (PH), or src homology 2 (SH2) domains inhibited any tested insulin response. Potentiation of the insulin response originated at the insulin receptor (IR) kinase level by PSM variant-specific regulation of the Km (ATP) whereas the Vmax remained unaffected. IR catalytic activation was inhibited by peptide mimetics of the PSM SH2 or dimerization domain (DD). Either peptide should disrupt the complex of a PSM dimer linked to IR via SH2 domains as proposed for PSM activation of tyrosine kinase JAK2. Either peptide abolished downstream insulin responses indistinguishable from PSM siRNA knockdown. Our results implicate an essential role of the PSM variants in the activation of the IR kinase and the resulting metabolic insulin response. PSM variants act as internal IR ligands that in addition to potentiating the insulin response stimulate IR catalytic activation even in the absence of insulin.

  6. A neglected modulator of insulin-degrading enzyme activity and conformation: The pH.

    Science.gov (United States)

    Grasso, Giuseppe; Satriano, Cristina; Milardi, Danilo

    2015-01-01

    Insulin-degrading enzyme (IDE), a ubiquitously expressed zinc metalloprotease, has multiple activities in addition to insulin degradation and its malfunction is believed to connect type 2 diabetes with Alzheimer's disease. IDE has been found in many different cellular compartments, where it may experience significant physio-pathological pH variations. However, the exact role of pH variations on the interplay between enzyme conformations, stability, oligomerization state and catalysis is not understood. Here, we use ESI mass spectrometry, atomic force microscopy, surface plasmon resonance and circular dichroism to investigate the structure-activity relationship of IDE at different pH values. We show that acidic pH affects the ability of the enzyme to bind the substrate and decrease the stability of the protein by inducing an α-helical bundle conformation with a concomitant dissociation of multi-subunit IDE assemblies into monomeric units and loss of activity. These effects suggest a major role played by electrostatic forces in regulating multi-subunit enzyme assembly and function. Our results clearly indicate a pH dependent coupling among enzyme conformation, assembly and stability and suggest that cellular acidosis can have a large effect on IDE oligomerization state, inducing an enzyme inactivation and an altered insulin degradation that could have an impact on insulin signaling.

  7. [Anaphylactic shock due to recombinant human insulin: follow-up of a desensitization protocol by basophil activation test].

    Science.gov (United States)

    Luyasu, S; Hougardy, N; Hasdenteufel, F; Jacquenet, S; Weber, E; Moneret-Vautrin, A; Kanny, G

    2011-01-01

    Despite the occurrence of a severe allergic reaction including an anaphylactic shock, a drug may remain essential and impossible to replace. This may be the case of insulin in a diabetic patient. We describe the case of an anaphylactic shock to human insulin in whom a desensitization protocol was successfully achieved. A 50-year-old type 2 diabetic man presented one year after initiation of the insulin therapy an anaphylactic shock following the subcutaneous administration of a human insulin containing protamine (Insulatard®). A desensitization protocol to human insulin was performed and allowed to use two human insulin analogues containing no protamine (asparte and glargine), with a two-year event-free follow-up. Positive skin tests with insulin and protamine, and the presence of insulin specific IgE were evidenced of an IgE-mediated mechanism. Desensitization was monitored by skin tests, Maunsell's test, measurement of specific IgE and IgG4, and the basophil activation test. The decrease of basophil sensitivity to insulin is an early marker for tolerance induction. The effectiveness of the desensitization to human insulin underlines the importance to define the modalities of such desensitization protocol and of the monitoring of the tolerance induction. Copyright © 2010 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.

  8. Activation of the insulin receptor (IR) by insulin and a synthetic peptide has different effects on gene expression in IR-transfected L6 myoblasts

    DEFF Research Database (Denmark)

    Jensen, M.; Palsgaard, J.; Borup, R.;

    2008-01-01

    differentially activates post-receptor signalling, we studied the gene expression profile in response to IR activation by either insulin or S597 using microarray technology. We found striking differences between the patterns induced by these two ligands. Most remarkable was that almost half of the genes...... differentially regulated by insulin and S597 were involved in cell proliferation and growth. Insulin either selectively regulated the expression of these genes or was a more potent regulator. Furthermore, we found that half of the differentially regulated genes interact with the genes involved with the MAPK...... differentially affect gene expression in cells, resulting in a different mitogenicity of the two ligands, a finding which has critical therapeutic implications Udgivelsesdato: 2008/6/15...

  9. Non-diabetic hyperglycemia exacerbates disease severity in Mycobacterium tuberculosis infected guinea pigs.

    Directory of Open Access Journals (Sweden)

    Brendan K Podell

    Full Text Available Hyperglycemia, the diagnostic feature of diabetes also occurs in non-diabetics associated with chronic inflammation and systemic insulin resistance. Since the increased risk of active TB in diabetics has been linked to the severity and duration of hyperglycemia, we investigated what effect diet-induced hyperglycemia had on the severity of Mycobacterium tuberculosis (Mtb infection in non-diabetic guinea pigs. Post-prandial hyperglycemia was induced in guinea pigs on normal chow by feeding a 40% sucrose solution daily or water as a carrier control. Sucrose feeding was initiated on the day of aerosol exposure to the H37Rv strain of Mtb and continued for 30 or 60 days of infection. Despite more severe hyperglycemia in sucrose-fed animals on day 30, there was no significant difference in lung bacterial or lesion burden until day 60. However the higher spleen and lymph node bacterial and lesion burden at day 30 indicated earlier and more severe extrapulmonary TB in sucrose-fed animals. In both sucrose- and water-fed animals, serum free fatty acids, important mediators of insulin resistance, were increased by day 30 and remained elevated until day 60 of infection. Hyperglycemia mediated by Mtb infection resulted in accumulation of advanced glycation end products (AGEs in lung granulomas, which was exacerbated by sucrose feeding. However, tissue and serum AGEs were elevated in both sucrose and water-fed guinea pigs by day 60. These data indicate that Mtb infection alone induces insulin resistance and chronic hyperglycemia, which is exacerbated by sucrose feeding. Moreover, Mtb infection alone resulted in the accumulation tissue and serum AGEs, which are also central to the pathogenesis of diabetes and diabetic complications. The exacerbation of insulin resistance and hyperglycemia by Mtb infection alone may explain why TB is more severe in diabetics with poorly controlled hyperglycemia compared to non-diabetics and patients with properly controlled

  10. Non-diabetic hyperglycemia exacerbates disease severity in Mycobacterium tuberculosis infected guinea pigs.

    Science.gov (United States)

    Podell, Brendan K; Ackart, David F; Kirk, Natalie M; Eck, Sarah P; Bell, Christopher; Basaraba, Randall J

    2012-01-01

    Hyperglycemia, the diagnostic feature of diabetes also occurs in non-diabetics associated with chronic inflammation and systemic insulin resistance. Since the increased risk of active TB in diabetics has been linked to the severity and duration of hyperglycemia, we investigated what effect diet-induced hyperglycemia had on the severity of Mycobacterium tuberculosis (Mtb) infection in non-diabetic guinea pigs. Post-prandial hyperglycemia was induced in guinea pigs on normal chow by feeding a 40% sucrose solution daily or water as a carrier control. Sucrose feeding was initiated on the day of aerosol exposure to the H37Rv strain of Mtb and continued for 30 or 60 days of infection. Despite more severe hyperglycemia in sucrose-fed animals on day 30, there was no significant difference in lung bacterial or lesion burden until day 60. However the higher spleen and lymph node bacterial and lesion burden at day 30 indicated earlier and more severe extrapulmonary TB in sucrose-fed animals. In both sucrose- and water-fed animals, serum free fatty acids, important mediators of insulin resistance, were increased by day 30 and remained elevated until day 60 of infection. Hyperglycemia mediated by Mtb infection resulted in accumulation of advanced glycation end products (AGEs) in lung granulomas, which was exacerbated by sucrose feeding. However, tissue and serum AGEs were elevated in both sucrose and water-fed guinea pigs by day 60. These data indicate that Mtb infection alone induces insulin resistance and chronic hyperglycemia, which is exacerbated by sucrose feeding. Moreover, Mtb infection alone resulted in the accumulation tissue and serum AGEs, which are also central to the pathogenesis of diabetes and diabetic complications. The exacerbation of insulin resistance and hyperglycemia by Mtb infection alone may explain why TB is more severe in diabetics with poorly controlled hyperglycemia compared to non-diabetics and patients with properly controlled blood glucose levels.

  11. Insulin acts in the arcuate nucleus to increase lumbar sympathetic nerve activity and baroreflex function in rats

    National Research Council Canada - National Science Library

    Cassaglia, Priscila A; Hermes, Sam M; Aicher, Sue A; Brooks, Virginia L

    2011-01-01

    Non‐technical summary  Though the pancreatic hormone insulin is known to act in the brain to increase sympathetic nerve activity and baroreflex control of sympathetic nerve activity, its specific site of action had yet to be identified...

  12. Maternal Physical Activity and Insulin Action in Pregnancy and Their Relationships With Infant Body Composition

    OpenAIRE

    Pomeroy, Jeremy; Renström, Frida; Gradmark, Anna M.; Mogren, Ingrid; Persson, Margareta; Bluck, Les; Wright, Antony; Kahn, Steven E; Domellöf, Magnus; Franks, Paul W.

    2013-01-01

    OBJECTIVE We sought to assess the association between maternal gestational physical activity and insulin action and body composition in early infancy. RESEARCH DESIGN AND METHODS At 28–32 weeks' gestation, pregnant women participating in an observational study in Sweden underwent assessments of height, weight, and body composition, an oral glucose tolerance test, and 10 days of objective physical activity assessment. Thirty mothers and infants returned at 11–19 weeks postpartum. Infants under...

  13. Activity restriction, impaired capillary function, and the development of insulin resistance in lean primates.

    Science.gov (United States)

    Chadderdon, Scott M; Belcik, J Todd; Smith, Elise; Pranger, Lindsay; Kievit, Paul; Grove, Kevin L; Lindner, Jonathan R

    2012-09-01

    Insulin produces capillary recruitment in skeletal muscle through a nitric oxide (NO)-dependent mechanism. Capillary recruitment is blunted in obese and diabetic subjects and contributes to impaired glucose uptake. This study's objective was to define whether inactivity, in the absence of obesity, leads to impaired capillary recruitment and contributes to insulin resistance (IR). A comprehensive metabolic and vascular assessment was performed on 19 adult male rhesus macaques (Macaca mulatta) after sedation with ketamine and during maintenance anesthesia with isoflurane. Thirteen normal-activity (NA) and six activity-restricted (AR) primates underwent contrast-enhanced ultrasound to determine skeletal muscle capillary blood volume (CBV) during an intravenous glucose tolerance test (IVGTT) and during contractile exercise. NO bioactivity was assessed by flow-mediated vasodilation. Although there were no differences in weight, basal glucose, basal insulin, or truncal fat, AR primates were insulin resistant compared with NA primates during an IVGTT (2,225 ± 734 vs. 5,171 ± 3,431 μg·ml⁻¹·min⁻¹, P obesity. Reduced NO bioactivity may be a pathological link between inactivity and impaired capillary function.

  14. [The role of peroxisome proliferator-activated receptors γ (PPARγ) in obesity and insulin resistance].

    Science.gov (United States)

    Chmielewska-Kassassir, Małgorzata; Woźniak, Lucyna A; Ogrodniczek, Paweł; Wójcik, Marzena

    2013-12-11

    Obesity, defined as abnormal or excessive fat accumulation, is currently believed to be a major public health problem worldwide. Over the past 20 years, the prevalence of obesity has increased rapidly in both industrialized and developing countries, resulting in a considerably increased risk of type 2 diabetes mellitus (T2DM) and metabolic syndrome. Although the exact pathophysiological mechanisms underlying these diseases remain unclear, clinical and epidemiological studies support the existence of a relationship between obesity-induced inflammation and insulin resistance linked with the development and progression of metabolic diseases. Adipokines, produced and released by adipose tissue, are considered as factors linking obesity-induced inflammation with insulin resistance, and their regulation through peroxisome proliferator-activated receptors γ (PPARγ also known as NR1C3) is essential in these processes. PPARγ are transcriptional factors belonging to the ligand-activated nuclear receptor superfamily which directly regulate the expression of a large number of genes involved in adipocyte differentiation, lipid and carbohydrate metabolism as well as adipokine synthesis; thereby they are implicated in various metabolic disorders, including obesity, insulin resistance, dyslipidemia, and hypertension. This review summarizes the current literature on a functional relationship of PPARγ with obesity and insulin resistance and, moreover, highlights the significance of synthetic ligands of these receptors in the mentioned metabolic disorders.

  15. Dealing with challenges in taking active part in care after hospitalization due to exacerbation in chronic obstructive pulmonary disease: experiences of patients and their relatives

    DEFF Research Database (Denmark)

    Andersen, Ingrid Charlotte; Thomsen, Thora Grothe; Poul, Bruun

    after discharge. A phenomenological-hermeneutical approach inspired by Ricoeurs’ theory of interpretation guided data analysis. Results: Preliminary results indicate that taking active part in COPD care implies managing periods with increased vulnerability created by the transition situation of hospital......Background: Living with severe chronic obstructive pulmonary disease (COPD) is often characterized by recurrent acute exacerbations (AECOPD) and increased need for hospitalization. After hospital discharge for AECOPD, many patients experience prolonged deterioration and difficulties in maintaining...... care within a year after hospitalization. Methods: An ethnographic inspired field study was conducted among fifteen COPD patients and twelve relatives. Data were collected by participant observation and informal interviews at hospital. This was supplemented by in-depth interviews six and twelve months...

  16. Bcl10 Links Saturated Fat Overnutrition with Hepatocellular NF-κB Activation and Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Matthew Van Beek

    2012-05-01

    Full Text Available Excess serum free fatty acids (FFAs are fundamental to the pathogenesis of insulin resistance. With high-fat feeding, FFAs activate NF-κB in target tissues, initiating negative crosstalk with insulin signaling. However, the mechanisms underlying FFA-dependent NF-κB activation remain unclear. Here, we demonstrate that the saturated FA, palmitate, requires Bcl10 for NF-κB activation in hepatocytes. Uptake of palmitate, metabolism to diacylglycerol, and subsequent activation of protein kinase C (PKC appear to mechanistically link palmitate with Bcl10, known as a central component of a signaling complex that, along with CARMA3 and MALT1, activates NF-κB downstream of selected cell surface receptors. Consequently, Bcl10-deficient mice are protected from hepatic NF-κB activation and insulin resistance following brief high-fat diet, suggesting that Bcl10 plays a major role in the metabolic consequences of acute overnutrition. Surprisingly, while CARMA3 also participates in the palmitate response, MALT1 is completely dispensable, thereby revealing an apparent nonclassical role for Bcl10 in NF-κB signaling.

  17. Direct Angiotensin II Type 2 Receptor Stimulation Ameliorates Insulin Resistance in Type 2 Diabetes Mice with PPARγ Activation

    DEFF Research Database (Denmark)

    Ohshima, Kousei; Mogi, Masaki; Jing, Fei

    2012-01-01

    The role of angiotensin II type 2 (AT(2)) receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT(2) receptor stimulation by compound 21 (C21) might contribute to possible insulin-sensitizing/anti-diabetic effects in ty...... 2 diabetes (T2DM) with PPARγ activation, mainly focusing on adipose tissue....

  18. Bavachin from Psoralea corylifolia Improves Insulin-Dependent Glucose Uptake through Insulin Signaling and AMPK Activation in 3T3-L1 Adipocytes

    Directory of Open Access Journals (Sweden)

    Hyejin Lee

    2016-04-01

    Full Text Available The fruit of Psoralea corylifolia L. (Fabaceae (PC, known as “Bo-Gol-Zhee” in Korea has been used as traditional medicine. Ethanol and aqueous extracts of PC have an anti-hyperglycemic effect by increasing plasma insulin levels and decreasing blood glucose and total plasma cholesterol levels in type 2 diabetic rats. In this study, we purified six compounds from PC and investigated their anti-diabetic effect. Among the purified compounds, bavachin most potently accumulated lipids during adipocyte differentiation. Intracellular lipid accumulation was measured by Oil Red-O (ORO cell staining to investigate the effect of compounds on adipogenesis. Consistently, bavachin activated gene expression of adipogenic transcriptional factors, proliferator-activated receptorγ (PPARγ and CCAAT/enhancer binding protein-α (C/EBPα. Bavachin also increased adiponectin expression and secretion in adipocytes. Moreover, bavachin increased insulin-induced glucose uptake by differentiated adipocytes and myoblasts. In differentiated adipocytes, we found that bavachin enhanced glucose uptake via glucose transporter 4 (GLUT4 translocation by activating the Akt and 5′AMP-activated protein kinase (AMPK pathway in the presence or absence of insulin. These results suggest that bavachin from Psoralea corylifolia might have therapeutic potential for type 2 diabetes by activating insulin signaling pathways.

  19. Programmed cell death-1 deficiency exacerbates T cell activation and atherogenesis despite expansion of regulatory T cells in atherosclerosis-prone mice.

    Directory of Open Access Journals (Sweden)

    Clément Cochain

    Full Text Available T cell activation represents a double-edged sword in atherogenesis, as it promotes both pro-inflammatory T cell activation and atheroprotective Foxp3(+ regulatory T cell (Treg responses. Here, we investigated the role of the co-inhibitory receptor programmed cell death-1 (PD-1 in T cell activation and CD4(+ T cell polarization towards pro-atherogenic or atheroprotective responses in mice. Mice deficient for both low density lipoprotein receptor and PD-1 (Ldlr(-/-Pd1(-/- displayed striking increases in systemic CD4(+ and CD8(+ T cell activation after 9 weeks of high fat diet feeding, associated with an expansion of both pro-atherogenic IFNγ-secreting T helper 1 cells and atheroprotective Foxp3+ Tregs. Importantly, PD-1 deficiency did not affect Treg suppressive function in vitro. Notably, PD-1 deficiency exacerbated atherosclerotic lesion growth and entailed a massive infiltration of T cells in atherosclerotic lesions. In addition, aggravated hypercholesterolemia was observed in Ldlr(-/-Pd1(-/- mice. In conclusion, we here demonstrate that although disruption of PD-1 signaling enhances both pro- and anti-atherogenic T cell responses in Ldlr(-/- mice, pro-inflammatory T cell activation prevails and enhances dyslipidemia, vascular inflammation and atherosclerosis.

  20. Associations of objective physical activity with insulin sensitivity and circulating adipokine profile: the Framingham Heart Study.

    Science.gov (United States)

    Spartano, N L; Stevenson, M D; Xanthakis, V; Larson, M G; Andersson, C; Murabito, J M; Vasan, R S

    2017-04-01

    The purpose of this study was to explore the relation of physical activity (PA) and sedentary time (SED) to insulin sensitivity and adipokines. We assessed PA and SED using Actical accelerometers and insulin resistance (HOMA-IR) in 2109 participants (free of type 1 and 2 diabetes mellitus) from Framingham Generation 3 and Omni 2 cohorts (mean age 46 years, 54% women). Systemic inflammation (C-reactive protein [CRP]) and circulating adipokines were measured 6 years earlier. Steps per day, moderate-to-vigorous PA (MVPA) and SED per wear time (%SED) were predictor variables in multivariable regression analyses, with HOMA-IR, CRP and circulating adipokines as outcome measures. We reported that higher MVPA and more steps per day were associated with lower HOMA-IR, adjusting for %SED (β = -0.036, P = 0.002; β = -0.041, P = 0.005). Steps were inversely associated with CRP, but were directly associated with insulin-like growth factor (IGF)-1 levels (β = -0.111, P = 0.002; β = 3.293, P = 0.007). %SED was positively associated with HOMA-IR (β = 0.033, P insulin resistance and inflammation, whereas SED influences FABPs.

  1. PTEN, a widely known negative regulator of insulin/PI3K signaling, positively regulates neuronal insulin resistance

    Science.gov (United States)

    Gupta, Amit; Dey, Chinmoy Sankar

    2012-01-01

    Lipid and protein tyrosine phosphatase, phosphatase and tension homologue (PTEN), is a widely known negative regulator of insulin/phosphoinositide 3-kinase signaling. Down-regulation of PTEN is thus widely documented to ameliorate insulin resistance in peripheral tissues such as skeletal muscle and adipose. However, not much is known about its exact role in neuronal insulin signaling and insulin resistance. Moreover, alterations of PTEN in neuronal systems have led to discovery of several unexpected outcomes, including in the neurodegenerative disorder Alzheimer's disease (AD), which is increasingly being recognized as a brain-specific form of diabetes. In addition, contrary to expectations, its neuron-specific deletion in mice resulted in development of diet-sensitive obesity. The present study shows that PTEN, paradoxically, positively regulates neuronal insulin signaling and glucose uptake. Its down-regulation exacerbates neuronal insulin resistance. The positive role of PTEN in neuronal insulin signaling is likely due to its protein phosphatase actions, which prevents the activation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK), the kinases critically involved in neuronal energy impairment and neurodegeneration. Results suggest that PTEN acting through FAK, the direct protein substrate of PTEN, prevents ERK activation. Our findings provide an explanation for unexpected outcomes reported earlier with PTEN alterations in neuronal systems and also suggest a novel molecular pathway linking neuronal insulin resistance and AD, the two pathophysiological states demonstrated to be closely linked. PMID:22875989

  2. Reduced insulin-mediated citrate synthase activity in cultured skeletal muscle cells from patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Mogensen, Martin; Petersen, Ingrid

    2005-01-01

    responded to high levels of insulin and/or palmitate. These results provide evidence for an intrinsic defect in CS activity, which may play a role in the pathogenesis of T2D. Moreover, the data suggest that insulin resistance at the CS level can be induced by exposure to high free fatty acid levels....... of these metabolic malfunctions, we studied mitochondrial respiration, uncoupled respiration and oxidative enzyme activities (citrate synthase (CS), 3-hydroxy-acyl-CoA-dehydrogenase activity (HAD)) before and after acute exposure to insulin and/or palmitate in myotubes established from healthy lean and obese...

  3. Insulin receptor binding and tyrosine kinase activity in skeletal muscle from normal pregnant women and women with gestational diabetes

    DEFF Research Database (Denmark)

    Damm, P; Handberg, A; Kühl, C

    1993-01-01

    OBJECTIVE: To ascertain whether the decreased glucose tolerance and insulin resistance found in normal and gestational diabetic pregnancy might be associated with changes in insulin receptor function. METHODS: Eight nonpregnant healthy women (nonpregnant controls), eight healthy pregnant women...... (pregnant controls), and eight women with gestational diabetes were investigated. All were non-obese. Muscle biopsies were obtained from the vastus lateralis muscle, and insulin binding and tyrosine kinase activities in partially purified skeletal muscle insulin receptors were studied. The pregnant controls...... with gestational diabetes compared to nonpregnant controls (P pregnant women did not differ from the other two groups. Postpartum, no differences in insulin binding were found between the groups. Basal and maximal tyrosine kinase activities toward the exogenous substrate poly(Glu4Tyr1) were...

  4. Genomic actions of 1,25-dihydroxyvitamin D3 on insulin receptor gene expression, insulin receptor number and insulin activity in the kidney, liver and adipose tissue of streptozotocin-induced diabetic rats

    Directory of Open Access Journals (Sweden)

    García-Arencibia Moisés

    2008-07-01

    Full Text Available Abstract Background this study set out to examine the effects of the treatment with 1,25-dihydroxyvitamin D3 (1,25D3 [150 IU/Kg (3.75 μg/Kg one a day, for 15 days] to non-diabetic rats and in rats rendered diabetic by a single injection of streptozotocin [65 mg/kg]. Results treatment with 1,25D3 to non-diabetic rats did not affect the biochemical parameters measured in the plasma and urine of these animals. Likewise, insulin receptor expression in the kidney, liver, or adipose tissue and insulin-stimulated glucose transport in adipocytes from these animals were not affected either. Treatment with 1,25D3 to streptozotocin-induced diabetic rats did not correct the hyperglycemia, hypoinsulinemia, glycosuria or ketonemia induced by the diabetes, although it partially reversed the over-expression of the insulin receptor gene in the liver and adipose tissue, without altering the normal expression of this gene in the kidney. These effects were accompanied by a normalization of the number of insulin receptors without altering receptor affinity but improving the insulin response to glucose transport in adipocytes from these diabetic animals. Moreover, a computer search in the rat insulin receptor promoter revealed the existence of two candidate vitamin D response element (VDRE sequences located at -256/-219 bp and -653/-620 bp, the first overlapped by three and the second by four AP-2-like sites. Conclusion these genomic actions of 1,25D3 could represent beneficial effects associated with the amelioration of diabetes via mechanisms that possibly involve direct transcriptional activation of the rat insulin receptor gene. The candidate VDREs identified may respond to 1,25D3 via activation of the vitamin D receptor, although this remains to be investigated.

  5. Soybean fermentation with Bacillus licheniformis increases insulin sensitizing and insulinotropic activity.

    Science.gov (United States)

    Yang, Hye Jeong; Kwon, Dae Young; Moon, Na Rang; Kim, Min Jung; Kang, Hee Joo; Jung, Do Yeon; Park, Sunmin

    2013-11-01

    Traditionally fermented soybeans (chungkookjang; TFC) may have potent anti-diabetic activity, depending on the ambient microorganisms and conditions. We hypothesized that one of the major Bacillus species in TFC contributes to the anti-diabetic activity and could be used to standardize a highly functional TFC. We tested the hypothesis by using cell-based studies to evaluate insulin sensitizing and insulinotropic action of chungkookjangs fermented with various Bacillus spp. and fermentation periods. The 70% methanol and water extracts of chungkookjang fermented with Bacillus licheniformis (BL) for 48 h contained similar profiles of isoflavonoids and peptides to methanol and water extracts of TFC with potent anti-diabetic activity. Water extracts (mainly containing peptides) of TFC and BL fermented for 48 h and 72 h had a better insulin sensitizing action via activating peroxisome proliferator-activated receptor-γ (PPAR-γ) and increased the expression of PPAR-γ in 3T3-L1 adipocytes better than unfermented cooked soybeans (CSB). The 70% methanol extracts (predominantly isoflavone aglycones) of BL fermented for 48 h and 72 h improved glucose-stimulated insulin secretion and protected β-cell viability better than CSB in insulinoma cells, and the improvement by BL was similar to TFC. In conclusion, the BL water extract fermented for 48 h exhibited equal insulin sensitization as TFC and BL methanol extract exerted similar insulinotropic actions to those of TFC. B. licheniformis may be one of the major microorganisms responsible for anti-diabetic actions of chungkookjang. It is important to make chungkookjang that retains the anti-diabetic properties of the most efficacious traditional chungkookjang using a standardized method.

  6. Early limited nitrosamine exposures exacerbate high fat diet-mediated type 2 diabetes and neurodegeneration

    Directory of Open Access Journals (Sweden)

    Longato Lisa

    2010-03-01

    Full Text Available Abstract Background Type 2 diabetes mellitus (T2DM and several types of neurodegeneration, including Alzheimer's, are linked to insulin-resistance, and chronic high dietary fat intake causes T2DM with mild neurodegeneration. Intra-cerebral Streptozotocin, a nitrosamine-related compound, causes neurodegeneration, whereas peripheral treatment causes DM. Hypothesis Limited early exposures to nitrosamines that are widely present in the environment, enhance the deleterious effects of high fat intake in promoting T2DM and neurodegeneration. Methods Long Evans rat pups were treated with N-nitrosodiethylamine (NDEA by i.p. injection, and upon weaning, they were fed with high fat (60%; HFD or low fat (5%; LFD chow for 8 weeks. Cerebella were harvested to assess gene expression, and insulin and insulin-like growth factor (IGF deficiency and resistance in the context of neurodegeneration. Results HFD ± NDEA caused T2DM, neurodegeneration with impairments in brain insulin, insulin receptor, IGF-2 receptor, or insulin receptor substrate gene expression, and reduced expression of tau and choline acetyltransferase (ChAT, which are regulated by insulin and IGF-1. In addition, increased levels of 4-hydroxynonenal and nitrotyrosine were measured in cerebella of HFD ± NDEA treated rats, and overall, NDEA+HFD treatment reduced brain levels of Tau, phospho-GSK-3β (reflecting increased GSK-3β activity, glial fibrillary acidic protein, and ChAT to greater degrees than either treatment alone. Finally, pro-ceramide genes, examined because ceramides cause insulin resistance, oxidative stress, and neurodegeneration, were significantly up-regulated by HFD and/or NDEA exposure, but the highest levels were generally present in brains of HFD+NDEA treated rats. Conclusions Early limited exposure to nitrosamines exacerbates the adverse effects of later chronic high dietary fat intake in promoting T2DM and neurodegeneration. The mechanism involves increased generation of

  7. [Does physical activity produce clinically significant changes during discontinuation of insulin pump in type 1 diabetic patients?].

    Science.gov (United States)

    Jankovec, Z; Cechurová, D; Cesák, V; Krčma, M; Zourek, M; Rušavý, Z

    2013-09-01

    Discontinuation of insulin pump treatment (CSII) before, during and after physical activity is a common practice among a number of patients. The aim of the study was to evaluate the course of insulinemia during a 3- hour insulin pump suspension and after consecutive insulin bolus administration, and additionally, to assess the effect of physical activity (mid intensity aerobic exercise). We enrolled 12 patients with diabetes mellitus type 1 in the study (men, mean age 33.4 ± 8.66 years, diabetes duration 16.3 ± 8.76 years, CSII treatment duration 6.9 ± 4.60 years, BMI 25.7 ± 3.75 mg/ m2, HbA1c 8.4 ± 0.95%, total insulin dose 50.3 ± 12.50 IU/ day). The tests were performed after night fasting at usual insulin doses, without serving breakfast and morning bolus dose. In the course of the test, insulin administration by a pump was suspended for 3 hours. Blood for assessment of blood glucose and insulinemia was taken in 30- minute intervals during the test. A test with or without physical exercise on bicycle ergometer was performed in each patient 2 weeks later. We did not prove any influence of physical exercise on insulinemia during suspended insulin deli-very by an insulin pump. Insulinemia of approximately 50% of the original value persisted for another 90 minutes following insulin pump suspension. A rapid increase in insulinemia occurred after bolus administration in the 180th minute of the test. However, the decrease in blood glucose level did not occur until after another 90 minutes. When modifying CSII treatment by reduction or suspension of insulin delivery it is essential to bear in mind the gradual decrease in insulinemia as well as the delay in insulin action following bolus administration.

  8. Corosolic acid inhibits adipose tissue inflammation and ameliorates insulin resistance via AMPK activation in high-fat fed mice.

    Science.gov (United States)

    Yang, Jie; Leng, Jing; Li, Jing-Jing; Tang, Jing-fu; Li, Yi; Liu, Bao-Lin; Wen, Xiao-Dong

    2016-02-15

    Adipose tissue inflammation is tightly associated with the development of insulin resistance. Corosolic acid (CRA), a natural triterpenoid, is well known as "phyto-insulin" due to its insulin-like activities. However, its underlying mechanism remains unknown. In this study, we investigated the mechanisms of CRA on improving insulin resistance both in vivo and in vitro. C57BL/6 mice were fed with normal diet, high-fat diet (HFD) or HFD with CRA, respectively. General biochemical parameters in blood and glucose intolerance in mice were assayed. Meanwhile, proinflammatory cytokines and macrophage infiltrations in adipose tissues were analyzed by real-time PCR and immunohistochemical staining. The effects of CRA on insulin signaling transduction and AMPK activity in adipose tissues were investigated by western blot. Furthermore, the effects of CRA on AMPK were confirmed on 3T3-L1 cells by using both AMPK inhibitor and AMPKα1/2-specific siRNA RESULTS: CRA attenuated hyperlipidemia, improved insulin sensitivity and glucose intolerance in mice. Meanwhile, it alleviated inflammation in adipose tissues, demonstrated by the suppression of IKKβ phosphorylation and down-regulation of gene expressions of proinflammatory cytokines. Histological analysis revealed that CRA attenuated macrophage infiltrations into adipose tissue. It also improved insulin signaling transduction by modification of Ser/Thr phosphorylation of IRS-1 and downstream Akt, thereby improved insulin sensitivity in HFD-fed mice. Furthermore, CRA regulated AMPK activation in a LKB1-dependent manner. AMPKα knockdown in adipocytes abolished the inhibitory effects of CRA on IKKβ and IRS-1 serine phosphorylation, indicating that CRA inhibited inflammation and ameliorated insulin resistance via AMPK activation. CRA inhibited inflammation with improvement in adipose tissue dysfunction and ameliorated insulin resistance in an AMPK-dependent manner. Copyright © 2016 Elsevier GmbH. All rights reserved.

  9. Hyperglycemia- and hyperinsulinemia-induced insulin resistance causes alterations in cellular bioenergetics and activation of inflammatory signaling in lymphatic muscle.

    Science.gov (United States)

    Lee, Yang; Fluckey, James D; Chakraborty, Sanjukta; Muthuchamy, Mariappan

    2017-07-01

    Insulin resistance is a well-known risk factor for obesity, metabolic syndrome (MetSyn) and associated cardiovascular diseases, but its mechanisms are undefined in the lymphatics. Mesenteric lymphatic vessels from MetSyn or LPS-injected rats exhibited impaired intrinsic contractile activity and associated inflammatory changes. Hence, we hypothesized that insulin resistance in lymphatic muscle cells (LMCs) affects cell bioenergetics and signaling pathways that consequently alter contractility. LMCs were treated with different concentrations of insulin or glucose or both at various time points to determine insulin resistance. Onset of insulin resistance significantly impaired glucose uptake, mitochondrial function, oxygen consumption rates, glycolysis, lactic acid, and ATP production in LMCs. Hyperglycemia and hyperinsulinemia also impaired the PI3K/Akt while enhancing the ERK/p38MAPK/JNK pathways in LMCs. Increased NF-κB nuclear translocation and macrophage chemoattractant protein-1 and VCAM-1 levels in insulin-resistant LMCs indicated activation of inflammatory mechanisms. In addition, increased phosphorylation of myosin light chain-20, a key regulator of lymphatic muscle contraction, was observed in insulin-resistant LMCs. Therefore, our data elucidate the mechanisms of insulin resistance in LMCs and provide the first evidence that hyperglycemia and hyperinsulinemia promote insulin resistance and impair lymphatic contractile status by reducing glucose uptake, altering cellular metabolic pathways, and activating inflammatory signaling cascades.-Lee, Y., Fluckey, J. D., Chakraborty, S., Muthuchamy, M. Hyperglycemia- and hyperinsulinemia-induced insulin resistance causes alterations in cellular bioenergetics and activation of inflammatory signaling in lymphatic muscle. © FASEB.

  10. Peroxisome proliferator-activated receptor γ decouples fatty acid uptake from lipid inhibition of insulin signaling in skeletal muscle.

    Science.gov (United States)

    Hu, Shanming; Yao, Jianrong; Howe, Alexander A; Menke, Brandon M; Sivitz, William I; Spector, Arthur A; Norris, Andrew W

    2012-06-01

    Peroxisome proliferator-activated receptor γ (PPARγ) is expressed at low levels in skeletal muscle, where it protects against adiposity and insulin resistance via unclear mechanisms. To test the hypothesis that PPARγ directly modulates skeletal muscle metabolism, we created two models that isolate direct PPARγ actions on skeletal myocytes. PPARγ was overexpressed in murine myotubes by adenotransfection and in mouse skeletal muscle by plasmid electroporation. In cultured myotubes, PPARγ action increased fatty acid uptake and incorporation into myocellular lipids, dependent upon a 154 ± 20-fold up-regulation of CD36 expression. PPARγ overexpression more than doubled insulin-stimulated thymoma viral proto-oncogene (AKT) phosphorylation during low lipid availability. Furthermore, in myotubes exposed to palmitate levels that inhibit insulin signaling, PPARγ overexpression increased insulin-stimulated AKT phosphorylation and glycogen synthesis over 3-fold despite simultaneously increasing myocellular palmitate uptake. The insulin signaling enhancement was associated with an increase in activating phosphorylation of phosphoinositide-dependent protein kinase 1 and a normalized expression of palmitate-induced genes that antagonize AKT phosphorylation. In vivo, PPARγ overexpression more than doubled insulin-dependent AKT phosphorylation in lipid-treated mice but did not augment insulin-stimulated glucose uptake. We conclude that direct PPARγ action promotes myocellular storage of energy by increasing fatty acid uptake and esterification while simultaneously enhancing insulin signaling and glycogen formation. However, direct PPARγ action in skeletal muscle is not sufficient to account for the hypoglycemic actions of PPARγ agonists during lipotoxicity.

  11. Dietary fibre consumption and insulin resistance - the role of body fat and physical activity.

    Science.gov (United States)

    Breneman, Charity B; Tucker, Larry

    2013-07-28

    The present study was conducted to determine the association between fibre intake and insulin resistance in 264 women using a cross-sectional design. Insulin resistance was indexed using homeostasis model assessment of insulin resistance (HOMA-IR) (US formula: fasting insulin (μU/ml) × fasting glucose (mg/dl)/405 international formula: fasting glucose (mmol/l) × fasting insulin (μU/l)/22.5). Fibre and energy consumption were assessed using 7 d weighed food records. Fibre was expressed as g/4184 kJ (1000 kcal). Body fat percentage (BF%) was measured using the BOD POD, and physical activity (PA) was ascertained using Actigraph accelerometers (Health One Technology) worn for seven consecutive days. Women with high total fibre intakes (F= 4·58, P= 0·0332) or high soluble fibre intakes (F= 7·97, P= 0·0051) had significantly less insulin resistance than their counterparts. Participants with high insoluble fibre intakes did not differ from their counterparts (F= 0·7, P= 0·6875). Adjusting for either PA or BF% weakened the relationships significantly. Controlling for BF% nullified the total fibre–HOMA-IR link (F= 1·96, P= 0·1631) and attenuated the association between soluble fibre and HOMA-IR by 32 % (F= 6·86, P= 0·0094). To create dichotomous variables, fibre intake and HOMA-IR were each divided into two categories using the median (low and high). In women who had high soluble fibre intake (upper 50 %), the OR of having an elevated HOMA-IR level was 0·58 (95 % CI 0·36, 0·94) times that of women with low soluble fibre intake (lower 50 %). After controlling for all of the potential confounding factors simultaneously, the OR was 0·52 (95 % CI 0·29, 0·93). High fibre intake, particularly soluble fibre, is significantly related to lower levels of insulin resistance in women. Part of this association is a function of differences in PA and BF%.

  12. Matrix Metalloproteinase-2 (MMP-2) Gene Deletion Enhances MMP-9 Activity, Impairs PARP-1 Degradation, and Exacerbates Hepatic Ischemia and Reperfusion Injury in Mice.

    Science.gov (United States)

    Kato, Hiroyuki; Duarte, Sergio; Liu, Daniel; Busuttil, Ronald W; Coito, Ana J

    2015-01-01

    Hepatic ischemia and reperfusion injury (IRI) is an inflammatory condition and a significant cause of morbidity and mortality after surgery. Matrix metalloproteinases (MMPs) have been widely implicated in the pathogenesis of inflammatory diseases. Among the different MMPs, gelatinases (MMP-2 and MMP-9) are within the most prominent MMPs detected during liver IRI. While the role of MMP-9 in liver damage has been fairly documented, direct evidence of the role for MMP-2 activity in hepatic IRI remains to be established. Due to the lack of suitable inhibitors to target individual MMPs in vivo, gene manipulation is as an essential tool to assess MMP direct contribution to liver injury. Hence, we used MMP-2-/- deficient mice and MMP-2+/+ wild-type littermates to examine the function of MMP-2 activity in hepatic IRI. MMP-2 expression was detected along the sinusoids of wild-type livers before and after surgery and in a small population of leukocytes post-IRI. Compared to MMP-2+/+ mice, MMP-2 null (MMP-2-/-) mice showed exacerbated liver damage at 6, 24, and 48 hours post-reperfusion, which was fatal in some cases. MMP-2 deficiency resulted in upregulation of MMP-9 activity, spontaneous leukocyte infiltration in naïve livers, and amplified MMP-9-dependent transmigration of leukocytes in vitro and after hepatic IRI. Moreover, complete loss of MMP-2 activity impaired the degradation of poly (ADP-ribose) polymerase (PARP-1) in extensively damaged livers post-reperfusion. However, the administration of a PARP-1 inhibitor to MMP-2 null mice restored liver preservation to almost comparable levels of MMP-2+/+ mice post-IRI. Deficient PARP-1 degradation in MMP-2-null sinusoidal endothelial cells correlated with their increased cytotoxicity, evaluated by the measurement of LDH efflux in the medium. In conclusion, our results show for the first time that MMP-2 gene deletion exacerbates liver IRI. Moreover, they offer new insights into the MMP-2 modulation of inflammatory responses

  13. Critical role of gap junction coupled KATP channel activity for regulated insulin secretion.

    Directory of Open Access Journals (Sweden)

    Jonathan V Rocheleau

    2006-02-01

    Full Text Available Pancreatic beta-cells secrete insulin in response to closure of ATP-sensitive K+ (KATP channels, which causes membrane depolarization and a concomitant rise in intracellular Ca2+ (Cai. In intact islets, beta-cells are coupled by gap junctions, which are proposed to synchronize electrical activity and Cai oscillations after exposure to stimulatory glucose (>7 mM. To determine the significance of this coupling in regulating insulin secretion, we examined islets and beta-cells from transgenic mice that express zero functional KATP channels in approximately 70% of their beta-cells, but normal KATP channel density in the remainder. We found that KATP channel activity from approximately 30% of the beta-cells is sufficient to maintain strong glucose dependence of metabolism, Cai, membrane potential, and insulin secretion from intact islets, but that glucose dependence is lost in isolated transgenic cells. Further, inhibition of gap junctions caused loss of glucose sensitivity specifically in transgenic islets. These data demonstrate a critical role of gap junctional coupling of KATP channel activity in control of membrane potential across the islet. Control via coupling lessens the effects of cell-cell variation and provides resistance to defects in excitability that would otherwise lead to a profound diabetic state, such as occurs in persistent neonatal diabetes mellitus.

  14. Critical role of gap junction coupled KATP channel activity for regulated insulin secretion.

    Science.gov (United States)

    Rocheleau, Jonathan V; Remedi, Maria S; Granada, Butch; Head, W Steven; Koster, Joseph C; Nichols, Colin G; Piston, David W

    2006-02-01

    Pancreatic beta-cells secrete insulin in response to closure of ATP-sensitive K+ (KATP) channels, which causes membrane depolarization and a concomitant rise in intracellular Ca2+ (Cai). In intact islets, beta-cells are coupled by gap junctions, which are proposed to synchronize electrical activity and Cai oscillations after exposure to stimulatory glucose (>7 mM). To determine the significance of this coupling in regulating insulin secretion, we examined islets and beta-cells from transgenic mice that express zero functional KATP channels in approximately 70% of their beta-cells, but normal KATP channel density in the remainder. We found that KATP channel activity from approximately 30% of the beta-cells is sufficient to maintain strong glucose dependence of metabolism, Cai, membrane potential, and insulin secretion from intact islets, but that glucose dependence is lost in isolated transgenic cells. Further, inhibition of gap junctions caused loss of glucose sensitivity specifically in transgenic islets. These data demonstrate a critical role of gap junctional coupling of KATP channel activity in control of membrane potential across the islet. Control via coupling lessens the effects of cell-cell variation and provides resistance to defects in excitability that would otherwise lead to a profound diabetic state, such as occurs in persistent neonatal diabetes mellitus.

  15. Total and free insulin-like growth factor I, insulin-like growth factor binding protein 3 and acid-labile subunit reflect clinical activity in acromegaly

    DEFF Research Database (Denmark)

    Sneppen, S B; Lange, Merete Wolder; Pedersen, L M

    2001-01-01

    the inactive and the active groups, we found that positive and negative predictive values (PV(pos), PV(neg)) for clinical disease activity of total and free insulin-like growth factor-I (IGF-I) were 0.59, 0.90 and 1.00, 0.82 respectively. Acid-labile subunit (ALS) showed diagnostic merit similar to insulin......-like growth factor binding protein-3 (IGFBP-3) with PV(pos) of 0.69 and 0.71 and PV(neg) of 0.91 and 0.92 respectively. We conclude that free IGF-I is more closely related than total IGF-I to perceived disease activity and is as such useful when evaluating previously treated acromegaly for disease activity...

  16. Interaction between physical activity and sleep duration in relation to insulin resistance among non-diabetic Chinese adults.

    Science.gov (United States)

    Zuo, Hui; Shi, Zumin; Yuan, Baojun; Dai, Yue; Hu, Gang; Wu, Gaolin; Hussain, Akhtar

    2012-03-28

    It is of a public health interest to explore the relationship between different types of physical activity, sleep duration and diabetes/insulin resistance. However, little is known about such relationship. This study examines the single and joint associations of different types of physical activity, and sleep duration on insulin resistance among non-diabetic Chinese adults. Data was collected from 1124 non-diabetic adults in Jiangsu Province from the China Health and Nutrition Survey (CHNS). Domestic, occupational, transportation and leisure physical activity were assessed in terms of metabolic equivalent (MET)-hours-per-week to account for both intensity and time spent. Sleep duration was categorized into three groups: ≤ 7 hours, 7-9 hours, and ≥ 9 hours. Insulin resistance was evaluated by the homeostasis model of assessment (HOMA) and defined as the highest quartile of HOMA. Total physical activity was mainly composed of occupational activity (75.1%), followed orderly by domestic, transportation and leisure time activity in both men and women. Total physical activity level was strongly negatively associated with fasting insulin and HOMA (p physical activity, occupational activity was significantly negatively associated with HOMA after full adjustment (p activity was also negatively associated with HOMA when adjusted for age and gender (p = 0.028). Moreover, the combination of low physical activity and short sleep duration was associated with the highest odds of insulin resistance (adjusted OR = 3.26, 95% CI: 1.57-6.78), compared to those with high physical activity and adequate sleep duration. Physical activity, mainly occupational physical activity, was negatively associated with insulin resistance in non-diabetic Chinese population, independently of potential confounders. There was a synergic effect of low physical activity and short sleep duration on insulin resistance.

  17. [EFFICIENCY OF COMBINATION OF ROFLUMILAST AND QUERCETIN FOR CORRECTION OXYGEN- INDEPENDENT MECHANISMS AND PHAGOCYTIC ACTIVITY OF MACROPHAGE CELLS OF PATIENTS WITH ACUTE EXACERBATION OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE WHEN COMBINED WITH CORONARY HEART DISEASE].

    Science.gov (United States)

    Gerych, P; Yatsyshyn, R

    2015-01-01

    Studied oxygen independent reaction and phagocytic activity of macrophage cells of patients with chronic obstructive pulmonary disease (COPD) II-III stage when combined with coronary heart disease (CHD). The increasing oxygen independent reactions monocytes and neutrophils and a decrease of the parameters that characterize the functional state of phagocytic cells, indicating a decrease in the functional capacity of macrophage phagocytic system (MPS) in patients with acute exacerbation of COPD, which runs as its own or in combination with stable coronary heart disease angina I-II. FC. Severity immunodeficiency state in terms of cellular component of nonspecific immunity in patients with acute exacerbation of COPD II-III stage in conjunction with the accompanying CHD increases with the progression of heart failure. Inclusion of basic therapy of COPD exacerbation and standard treatment of coronary artery disease and drug combinations Roflumilastand quercetin causes normalization of phagocytic indices MFS, indicating improved immune status and improves myocardial perfusion in terms of daily ECG monitoring.

  18. Lifelong Physical Activity Prevents Aging-Associated Insulin Resistance in Human Skeletal Muscle Myotubes via Increased Glucose Transporter Expression.

    Directory of Open Access Journals (Sweden)

    Tipwadee Bunprajun

    Full Text Available Both aging and physical inactivity are associated with increased development of insulin resistance whereas physical activity has been shown to promote increased insulin sensitivity. Here we investigated the effects of physical activity level on aging-associated insulin resistance in myotubes derived from human skeletal muscle satellite cells. Satellite cells were obtained from young (22 yrs normally active or middle-aged (56.6 yrs individuals who were either lifelong sedentary or lifelong active. Both middle-aged sedentary and middle-aged active myotubes had increased p21 and myosin heavy chain protein expression. Interestingly MHCIIa was increased only in myotubes from middle-aged active individuals. Middle-aged sedentary cells had intact insulin-stimulated Akt phosphorylation however, the same cell showed ablated insulin-stimulated glucose uptake and GLUT4 translocation to the plasma membrane. On the other hand, middle-aged active cells retained both insulin-stimulated increases in glucose uptake and GLUT4 translocation to the plasma membrane. Middle-aged active cells also had significantly higher mRNA expression of GLUT1 and GLUT4 compared to middle-aged sedentary cells, and significantly higher GLUT4 protein. It is likely that physical activity induces a number of stable adaptations, including increased GLUT4 expression that are retained in cells ex vivo and protect, or delay the onset of middle-aged-associated insulin resistance. Additionally, a sedentary lifestyle has an impact on the metabolism of human myotubes during aging and may contribute to aging-associated insulin resistance through impaired GLUT4 localization.

  19. Impaired insulin activation and dephosphorylation of glycogen synthase in skeletal muscle of women with polycystic ovary syndrome is reversed by pioglitazone treatment

    DEFF Research Database (Denmark)

    Glintborg, Dorte; Højlund, Kurt; Andersen, Nicoline Resen

    2008-01-01

    . No significant abnormalities in GSK-3alpha or -3beta were found in PCOS subjects. Pioglitazone treatment improved insulin-stimulated glucose metabolism and GS activity in PCOS (all P ... of GS including absent dephosphorylation at sites 2+2a contributes to insulin resistance in skeletal muscle in PCOS. The ability of pioglitazone to enhance insulin sensitivity, in part, involves improved insulin action on GS activity and dephosphorylation at NH2-terminal sites....

  20. Lifelong Physical Activity Prevents Aging-Associated Insulin Resistance in Human Skeletal Muscle Myotubes via Increased Glucose Transporter Expression

    DEFF Research Database (Denmark)

    Bunprajun, Tipwadee; Henriksen, Tora Ida; Scheele, Camilla

    2013-01-01

    chain protein expression. Interestingly MHCIIa was increased only in myotubes from middle-aged active individuals. Middle-aged sedentary cells had intact insulin-stimulated Akt phosphorylation however, the same cell showed ablated insulin-stimulated glucose uptake and GLUT4 translocation to the plasma...... membrane. On the other hand, middle-aged active cells retained both insulin-stimulated increases in glucose uptake and GLUT4 translocation to the plasma membrane. Middle-aged active cells also had significantly higher mRNA expression of GLUT1 and GLUT4 compared to middle-aged sedentary cells......, and significantly higher GLUT4 protein. It is likely that physical activity induces a number of stable adaptations, including increased GLUT4 expression that are retained in cells ex vivo and protect, or delay the onset of middle-aged-associated insulin resistance. Additionally, a sedentary lifestyle has an impact...

  1. Effects of soybean oligosaccharides on antioxidant enzyme activities and insulin resistance in pregnant women with gestational diabetes mellitus.

    Science.gov (United States)

    Fei, Bei-bei; Ling, Li; Hua, Chen; Ren, Shu-yan

    2014-09-01

    The effects of soybean oligosaccharides (SBOS) on antioxidant enzyme activities and insulin resistance in pregnant women with gestational diabetes mellitus (GDM) were investigated. Ninety-seven pregnant women with GDM were randomly divided into two groups, the control group (51 cases) and the SBOS group (46 cases). Before the group separation, the blood sugar level in patients was maintained stable by regular diet and insulin treatment. The control group was continued with the insulin treatment, while the SBOS group was treated with the combination of insulin and SBOS. Results showed that SBOS were able to reduce oxidative stress and alleviate insulin resistance in pregnant women with GDM, which indicates that SBOS may play an important role in the control of GDM complications.

  2. Leptin Regulated Insulin Secretion via Stimulating IRS2-associated Phosphoinositide 3-kinase Activity in the isolated Rat Pancreatic Islets

    Institute of Scientific and Technical Information of China (English)

    袁莉; 安汉祥; 李卓娅; 邓秀玲

    2003-01-01

    To investigate the molecular mechanism of leptin regulating insulin secretion through determining the regulation of insulin secretion and the insulin receptor substrate (IRS)-2-associated phosphoinositide 3-kinase (PI3K) activity by leptin in the isolated rat pancreatic islets, pancreatic islets were isolated from male SD rats by the collagenase method. The purified islets were incubated with leptin 2 nmol/L for 1 h in the presence of 5.6 mmol/L or 11.1 mmol/L glucose. Insulin release was measured using radioimmunoassay. IRS-2-associated activity of PI3K was determined by immunoprecipitate assay and Western blot. The results showed that in the presence of 5.6 mmol/L glucose, leptin had no significant effect on both insulin secretion and IRS-2-associated PI3K activity, but in the presence of 11.1 mmol/L glucose, insulin release was significantly inhibited after the islets were exposed to leptin for 1 h (P<0. 01). PI3K inhibitor wortmannin blocked the inhibitory regulation of leptin on insulin release (P<0. 05). Western Blot assay revealed that 2 nmol/L leptin could significantly increase the IRS-2-associated activity of PI3K by 51.5 % (P<0. 05) in the presence of 11.1 mmol/L glucose. It was concluded that Leptin could significantly inhibit insulin secretion in the presence of 11.1 mmol/L glucose by stimulating IRS-2-associated activity of PI3K, which might be the molecular mechanism of leptin regulating insulin secretion.

  3. Hydrogen peroxide induces activation of insulin signaling pathway via AMP-dependent kinase in podocytes

    Energy Technology Data Exchange (ETDEWEB)

    Piwkowska, Agnieszka, E-mail: apiwkowska@cmdik.pan.pl [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Rogacka, Dorota; Angielski, Stefan [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Jankowski, Maciej [Mossakowski Medical Research Centre, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdansk (Poland); Medical University of Gdansk, Department of Therapy Monitoring and Pharmacogenetics (Poland)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer H{sub 2}O{sub 2} activates the insulin signaling pathway and glucose uptake in podocytes. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} induces time-dependent changes in AMPK phosphorylation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} enhances insulin signaling pathways via AMPK activation. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} stimulation of glucose uptake is AMPK-dependent. -- Abstract: Podocytes are cells that form the glomerular filtration barrier in the kidney. Insulin signaling in podocytes is critical for normal kidney function. Insulin signaling is regulated by oxidative stress and intracellular energy levels. We cultured rat podocytes to investigate the effects of hydrogen peroxide (H{sub 2}O{sub 2}) on the phosphorylation of proximal and distal elements of insulin signaling. We also investigated H{sub 2}O{sub 2}-induced intracellular changes in the distribution of protein kinase B (Akt). Western blots showed that H{sub 2}O{sub 2} (100 {mu}M) induced rapid, transient phosphorylation of the insulin receptor (IR), the IR substrate-1 (IRS1), and Akt with peak activities at 5 min ({Delta} 183%, P < 0.05), 3 min ({Delta} 414%, P < 0.05), and 10 min ({Delta} 35%, P < 0.05), respectively. Immunostaining cells with an Akt-specific antibody showed increased intensity at the plasma membrane after treatment with H{sub 2}O{sub 2}>. Furthermore, H{sub 2}O{sub 2} inhibited phosphorylation of the phosphatase and tensin homologue (PTEN; peak activity at 10 min; {Delta} -32%, P < 0.05) and stimulated phosphorylation of the AMP-dependent kinase alpha subunit (AMPK{alpha}; 78% at 3 min and 244% at 10 min). The stimulation of AMPK was abolished with an AMPK inhibitor, Compound C (100 {mu}M, 2 h). Moreover, Compound C significantly reduced the effect of H{sub 2}O{sub 2} on IR phosphorylation by about 40% (from 2.07 {+-} 0.28 to 1.28 {+-} 0.12, P < 0.05). In addition, H{sub 2}O{sub 2} increased glucose uptake in podocytes

  4. TLR4 mutation reduces microglial activation, increases Aβ deposits and exacerbates cognitive deficits in a mouse model of Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Song Min

    2011-08-01

    Full Text Available Abstract Background Amyloid plaques, a pathological hallmark of Alzheimer's disease (AD, are accompanied by activated microglia. The role of activated microglia in the pathogenesis of AD remains controversial: either clearing Aβ deposits by phagocytosis or releasing proinflammatory cytokines and cytotoxic substances. Microglia can be activated via toll-like receptors (TLRs, a class of pattern-recognition receptors in the innate immune system. We previously demonstrated that an AD mouse model homozygous for a loss-of-function mutation of TLR4 had increases in Aβ deposits and buffer-soluble Aβ in the brain as compared with a TLR4 wild-type AD mouse model at 14-16 months of age. However, it is unknown if TLR4 signaling is involved in initiation of Aβ deposition as well as activation and recruitment of microglia at the early stage of AD. Here, we investigated the role of TLR4 signaling and microglial activation in early stages using 5-month-old AD mouse models when Aβ deposits start. Methods Microglial activation and amyloid deposition in the brain were determined by immunohistochemistry in the AD models. Levels of cerebral soluble Aβ were determined by ELISA. mRNA levels of cytokines and chemokines in the brain and Aβ-stimulated monocytes were quantified by real-time PCR. Cognitive functions were assessed by the Morris water maze. Results While no difference was found in cerebral Aβ load between AD mouse models at 5 months with and without TLR4 mutation, microglial activation in a TLR4 mutant AD model (TLR4M Tg was less than that in a TLR4 wild-type AD model (TLR4W Tg. At 9 months, TLR4M Tg mice had increased Aβ deposition and soluble Aβ42 in the brain, which were associated with decrements in cognitive functions and expression levels of IL-1β, CCL3, and CCL4 in the hippocampus compared to TLR4W Tg mice. TLR4 mutation diminished Aβ-induced IL-1β, CCL3, and CCL4 expression in monocytes. Conclusion This is the first demonstration of TLR4

  5. CHANGES IN LEVELS OF SOLUBLE T-CELL ACTIVATION MARKERS, SIL-2R, SCD4 AND SCD8, IN RELATION TO DISEASE EXACERBATIONS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS - A PROSPECTIVE-STUDY

    NARCIS (Netherlands)

    SPRONK, P.E.; TERBORG, E.J.; HUITEMA, M.G.; Limburg, Piet; Kallenberg, Cees

    1994-01-01

    Objectives-To assess serial activation of T-cell subsets in relation to auto-antibody production and the occurrence of disease exacerbations in patients with systemic lupus erythematosus (SLE). Methods-To study the possible role of T-cells in the pathophysiology of the disease, 16 consecutive exacer

  6. nitric oxide triggers the phosphatidylinositol 3-kinase/Akt survival pathway in insulin-producing RINm5F cells by arousing Src to activate insulin receptor substrate-1.

    Science.gov (United States)

    Tejedo, Juan R; Cahuana, Gladys M; Ramírez, Remedios; Esbert, Margarida; Jiménez, Juan; Sobrino, Francisco; Bedoya, Francisco J

    2004-05-01

    Mechanisms involved in the protective action of nitric oxide (NO) in insulin-producing cells are a matter of debate. We have previously shown that pharmacological inhibition of c-Src cancels the antiapoptotic action of low and sustained concentrations of exogenous NO. In this study, using insulin-producing RINm5F cells that overexpress Src either permanently active (v-Src) or dominant negative (dn-Src) forms, we determine that this tyrosine kinase is the principal mediator of the protective action of NO. We also show that Src-directed activation of insulin receptor substrate-1, phosphatidylinositol 3-kinase (PI3K), Akt, and Bad phosphorylation conform a substantial component of the survival route because pharmacological inhibition of PI3K and Akt canceled the antiapoptotic effects of NO. Studies performed with the protein kinase G (PKG) inhibitor KT-5823 revealed that NO-dependent activation of c-Src/ insulin receptor substrate-1 is not affected by PKG activation. By contrast, Akt and Bad activation are partially dependent on PKG activation. Endogenous production of NO after overexpression of endothelial nitric oxide synthase in RINm5F cells mimics the effects produced by generation of low amounts of NO from exogenous diethylenetriamine/NO. In addition, we found that NO produces c-Src/PI3K- and PKG-dependent activation of ERK 1/2. The MAPK kinase inhibitor PD 98059 suppresses NO-dependent protection from DNA fragmentation induced by serum deprivation. The protective action of low and sustained concentration of NO is also observed in staurosporine- and Taxol-induced apoptosis. Finally, NO also protects isolated rat islets from DNA fragmentation induced by serum deprivation. These data strengthen the notion that NO production at physiological levels plays a role in protection from apoptosis in pancreatic beta-cells.

  7. Fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhi-Qin [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China); College of Pharmaceutical Sciences, key laboratory of pharmaceutical quality control of Hebei province, Hebei University, Baoding 071002 (China); Liu, Ting; Chen, Chuan [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China); Li, Ming-Yan; Wang, Zi-Yu; Chen, Ruo-song; Wei, Gui-xiang; Wang, Xiao-yi [College of Pharmaceutical Sciences, key laboratory of pharmaceutical quality control of Hebei province, Hebei University, Baoding 071002 (China); Luo, Du-Qiang, E-mail: duqiangluo999@126.com [College of Life Sciences, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002 (China)

    2015-05-15

    Insulin resistance is a characteristic feature of type 2 diabetes mellitus (T2DM) and is characterized by defects in insulin signaling. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathways, and its increased activity and expression are implicated in the pathogenesis of insulin resistance. Therefore, the inhibition of PTP1B is anticipated to become a potential therapeutic strategy to treat T2DM. Fumosorinone (FU), a new natural product isolated from insect fungi Isaria fumosorosea, was found to inhibit PTP1B activity in our previous study. Herein, the effects of FU on insulin resistance and mechanism in vitro and in vivo were investigated. FU increased the insulin-provoked glucose uptake in insulin-resistant HepG2 cells, and also reduced blood glucose and lipid levels of type 2 diabetic KKAy mice. FU decreased the expression of PTP1B both in insulin-resistant HepG2 cells and in liver tissues of diabetic KKAy mice. Furthermore, FU increased the phosphorylation of IRβ, IRS-2, Akt, GSK3β and Erk1/2 in insulin-resistant HepG2 cells, as well as the phosphorylation of IRβ, IRS-2, Akt in liver tissues of diabetic KKAy mice. These results showed that FU increased glucose uptake and improved insulin resistance by down-regulating the expression of PTP1B and activating the insulin signaling pathway, suggesting that it may possess antidiabetic properties. - Highlights: • Fumosorinone is a new PTP1B inhibitor isolated from insect pathogenic fungi. • Fumosorinone attenuated the insulin resistance both in vitro and in vivo. • Fumosorinone decreased the expression of PTP1B both in vitro and in vivo. • Fumosorinone activated the insulin signaling pathway both in vitro and in vivo.

  8. Nandinine, a Derivative of Berberine, Inhibits Inflammation and Reduces Insulin Resistance in Adipocytes via Regulation of AMP-Kinase Activity.

    Science.gov (United States)

    Zhao, Wenwen; Ge, Haixia; Liu, Kang; Chen, Xiuping; Zhang, Jian; Liu, Baolin

    2017-02-01

    Nandinine is a derivative of berberine that has high efficacy for treating cardiovascular diseases. This study investigated the effects of berberine and nandinine on the regulation of insulin sensitivity in adipocytes. Through treatment with macrophage-derived conditioned medium in 3T3-L1 adipocytes, dysregulation of adipokine production and activation of the IκB kinase β/nuclear factor-kappa B pathway was induced. However, these phenomena were effectively reversed by berberine, nandinine, and salicylate pretreatments. Furthermore, both berberine and nandinine inhibited serine phosphorylation of insulin receptor substrate-1 induced by IκB kinase β and increased tyrosine phosphorylation of insulin receptor substrate-1 to activate the PI3K/Akt pathway, which finally led to insulin-mediated glucose uptake. In addition, berberine and nandinine significantly increased AMP-activated protein kinase activity, thereby contributing to their anti-inflammatory effect by inhibiting IκB kinase β activation. Finally, in vivo studies demonstrated that both berberine (100 or 200 mg/kg) and nandinine (100 or 200 mg/kg) effectively ameliorated glucose intolerance and induced the insulin sensitivity index in mice. In conclusion, berberine and nandinine attenuated insulin resistance in adipocytes by inhibiting inflammation in an AMP-activated protein kinase-dependent manner. Berberine and nandinine may be used as dietary supplements and nandinine is a new candidate for obesity treatment.

  9. Traumatic brain injury and obesity induce persistent central insulin resistance.

    Science.gov (United States)

    Karelina, Kate; Sarac, Benjamin; Freeman, Lindsey M; Gaier, Kristopher R; Weil, Zachary M

    2016-04-01

    Traumatic brain injury (TBI)-induced impairments in cerebral energy metabolism impede tissue repair and contribute to delayed functional recovery. Moreover, the transient alteration in brain glucose utilization corresponds to a period of increased vulnerability to the negative effects of a subsequent TBI. In order to better understand the factors contributing to TBI-induced central metabolic dysfunction, we examined the effect of single and repeated TBIs on brain insulin signalling. Here we show that TBI induced acute brain insulin resistance, which resolved within 7 days following a single injury but persisted until 28 days following repeated injuries. Obesity, which causes brain insulin resistance and neuroinflammation, exacerbated the consequences of TBI. Obese mice that underwent a TBI exhibited a prolonged reduction of Akt (also known as protein kinase B) signalling, exacerbated neuroinflammation (microglial activation), learning and memory deficits, and anxiety-like behaviours. Taken together, the transient changes in brain insulin sensitivity following TBI suggest a reduced capacity of the injured brain to respond to the neuroprotective and anti-inflammatory actions of insulin and Akt signalling, and thus may be a contributing factor for the damaging neuroinflammation and long-lasting deficits that occur following TBI. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  10. Serum soluble urokinase-type plasminogen activator receptor levels in male patients with acute exacerbation of schizophrenia.

    Science.gov (United States)

    Genc, Abdullah; Kalelioglu, Tevfik; Karamustafalioglu, Nesrin; Tasdemir, Akif; Genc, Esra Sena; Akkus, Mustafa; Emul, Murat

    2016-02-28

    Inflammatory abnormalities have been shown in the pathogenesis of schizophrenia. Soluble urokinase-type plasminogen activator receptor (suPAR) is a protein that is measurable in the circulating blood and reflects the inflammation in the body. We aimed to investigate serum suPAR levels in patients with schizophrenia who were in acute state and to compare with healthy controls. Forty five patients and 43 healthy controls were included in the study. We found no significant difference in suPAR levels between patients and controls, suggesting that suPAR as an inflammatory marker does not have a role in the inflammatory process of acute schizophrenia.

  11. Inositol phosphates and phosphoinositides activate insulin-degrading enzyme, while phosphoinositides also mediate binding to endosomes.

    Science.gov (United States)

    Song, Eun Suk; Jang, HyeIn; Guo, Hou-Fu; Juliano, Maria A; Juliano, Luiz; Morris, Andrew J; Galperin, Emilia; Rodgers, David W; Hersh, Louis B

    2017-04-04

    Insulin-degrading enzyme (IDE) hydrolyzes bioactive peptides, including insulin, amylin, and the amyloid β peptides. Polyanions activate IDE toward some substrates, yet an endogenous polyanion activator has not yet been identified. Here we report that inositol phosphates (InsPs) and phosphatdidylinositol phosphates (PtdInsPs) serve as activators of IDE. InsPs and PtdInsPs interact with the polyanion-binding site located on an inner chamber wall of the enzyme. InsPs activate IDE by up to ∼95-fold, affecting primarily Vmax The extent of activation and binding affinity correlate with the number of phosphate groups on the inositol ring, with phosphate positional effects observed. IDE binds PtdInsPs from solution, immobilized on membranes, or presented in liposomes. Interaction with PtdInsPs, likely PtdIns(3)P, plays a role in localizing IDE to endosomes, where the enzyme reportedly encounters physiological substrates. Thus, InsPs and PtdInsPs can serve as endogenous modulators of IDE activity, as well as regulators of its intracellular spatial distribution.

  12. Glucagon and Insulin Cooperatively Stimulate Fibroblast Growth Factor 21 Gene Transcription by Increasing the Expression of Activating Transcription Factor 4.

    Science.gov (United States)

    Alonge, Kimberly M; Meares, Gordon P; Hillgartner, F Bradley

    2017-03-31

    Previous studies have shown that glucagon cooperatively interacts with insulin to stimulate hepatic FGF21 gene expression. Here we investigated the mechanism by which glucagon and insulin increased FGF21 gene transcription in primary hepatocyte cultures. Transfection analyses demonstrated that glucagon plus insulin induction of FGF21 transcription was conferred by two activating transcription factor 4 (ATF4) binding sites in the FGF21 gene. Glucagon plus insulin stimulated a 5-fold increase in ATF4 protein abundance, and knockdown of ATF4 expression suppressed the ability of glucagon plus insulin to increase FGF21 expression. In hepatocytes incubated in the presence of insulin, treatment with a PKA-selective agonist mimicked the ability of glucagon to stimulate ATF4 and FGF21 expression. Inhibition of PKA, PI3K, Akt, and mammalian target of rapamycin complex 1 (mTORC1) suppressed the ability of glucagon plus insulin to stimulate ATF4 and FGF21 expression. Additional analyses demonstrated that chenodeoxycholic acid (CDCA) induced a 6-fold increase in ATF4 expression and that knockdown of ATF4 expression suppressed the ability of CDCA to increase FGF21 gene expression. CDCA increased the phosphorylation of eIF2α, and inhibition of eIF2α signaling activity suppressed CDCA regulation of ATF4 and FGF21 expression. These results demonstrate that glucagon plus insulin increases FGF21 transcription by stimulating ATF4 expression and that activation of cAMP/PKA and PI3K/Akt/mTORC1 mediates the effect of glucagon plus insulin on ATF4 expression. These results also demonstrate that CDCA regulation of FGF21 transcription is mediated at least partially by an eIF2α-dependent increase in ATF4 expression. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Activation of AMPK improves inflammation and insulin resistance in adipose tissue and skeletal muscle from pregnant women.

    Science.gov (United States)

    Liong, Stella; Lappas, Martha

    2015-12-01

    Gestational diabetes mellitus (GDM) is characterised by maternal peripheral insulin resistance and inflammation. Sterile inflammation and bacterial infection are key mediators of this enhanced inflammatory response. Adenosine monophosphate (AMP)-activated kinase (AMPK), which is decreased in insulin resistant states, possesses potent pro-inflammatory actions. There are, however, no studies on the role of AMPK in pregnancies complicated by GDM. Thus, the aims of this study were (i) to compare the expression of AMPK in adipose tissue and skeletal muscle from women with GDM and normal glucose-tolerant (NGT) pregnant women; and (ii) to investigate the effect of AMPK activation on inflammation and insulin resistance induced by the bacterial endotoxin lipopolysaccharide (LPS) and the pro-inflammatory cytokine IL-1β. When compared to NGT pregnant women, AMPKα activity was significantly lower in women with GDM as evidenced by a decrease in threonine phosphorylation of AMPKα. Activation of AMPK, using two pharmacologically distinct compounds, AICAR or phenformin, significantly suppressed LPS- or IL-1β-induced gene expression and secretion of pro-inflammatory cytokine IL-6, the chemokines IL-8 and MCP-1, and COX-2 and subsequent prostaglandin release from adipose tissue and skeletal muscle. In addition, activators of AMPK decreased skeletal muscle insulin resistance induced by LPS or IL-1β as evidenced by increased insulin-stimulated phosphorylation of IRS-1, GLUT-4 expression and glucose uptake. These findings suggest that AMPK may play an important role in inflammation and insulin resistance.

  14. Subthreshold α2-Adrenergic Activation Counteracts Glucagon-Like Peptide-1 Potentiation of Glucose-Stimulated Insulin Secretion

    Directory of Open Access Journals (Sweden)

    Minglin Pan

    2011-01-01

    Full Text Available The pancreatic β cell harbors α2-adrenergic and glucagon-like peptide-1 (GLP-1 receptors on its plasma membrane to sense the corresponding ligands adrenaline/noradrenaline and GLP-1 to govern glucose-stimulated insulin secretion. However, it is not known whether these two signaling systems interact to gain the adequate and timely control of insulin release in response to glucose. The present work shows that the α2-adrenergic agonist clonidine concentration-dependently depresses glucose-stimulated insulin secretion from INS-1 cells. On the contrary, GLP-1 concentration-dependently potentiates insulin secretory response to glucose. Importantly, the present work reveals that subthreshold α2-adrenergic activation with clonidine counteracts GLP-1 potentiation of glucose-induced insulin secretion. This counteractory process relies on pertussis toxin- (PTX- sensitive Gi proteins since it no longer occurs following PTX-mediated inactivation of Gi proteins. The counteraction of GLP-1 potentiation of glucose-stimulated insulin secretion by subthreshold α2-adrenergic activation is likely to serve as a molecular mechanism for the delicate regulation of insulin release.

  15. Physical activity energy expenditure may mediate the relationship between plasma leptin levels and worsening insulin resistance independently of adiposity.

    Science.gov (United States)

    Franks, P W; Loos, R J F; Brage, S; O'Rahilly, S; Wareham, N J; Ekelund, U

    2007-05-01

    Leptin regulates a constellation of neuroendocrine processes that control energy homeostasis. The infusion of leptin in rodents lacking endogenous leptin promotes physical activity energy expenditure (PAEE) and improves insulin signaling, whereas hyperleptinemia is associated with physical inactivity and insulin resistance (IR). We tested whether baseline leptin levels predict changes in PAEE and IR over time, independent of obesity. We also assessed whether the relationship between leptin and change in IR is mediated by PAEE. The population consisted of 288 nondiabetic UK Caucasian adults (mean age: 49.4 yr; SD: 0.7 yr), in whom leptin, insulin, glucose, PAEE (via heart rate monitoring with individual calibration by indirect calorimetry), and anthropometric characteristics had been measured at baseline and 5 yr later. In linear regression models, baseline leptin levels inversely predicted follow-up PAEE (P = 0.033). On average, individuals with low leptin levels (below sex-specific median) increased their daily activity 35% more during the 5-yr follow-up period than those with above-median leptin levels. Baseline leptin level also predicted worsening IR (fasting, 30-min, and 2-h insulins, and homeostasis model assessment-IR; all P independent of potential confounders, such as adiposity, age, and sex. Including baseline PAEE as a cofactor in the leptin-insulin models reduced the strength (1-4% reduction) and significance of the associations, suggesting that PAEE mediates the leptin-insulin relationships. Hyperleptinemia predicts a relative decline in PAEE and worsening insulin resistance, possibly via shared molecular pathways.

  16. The novel functions of high-molecular-mass complexes containing insulin receptor substrates in mediation and modulation of insulin-like activities: Emerging concept of diverse function by IRS-associated proteins

    Directory of Open Access Journals (Sweden)

    Fumihiko eHakuno

    2015-05-01

    Full Text Available Insulin-like peptides, such as insulin and insulin-like growth factors (IGFs, induce a variety of bioactivities, such as growth, differentiation, survival, increased anabolism and decreased catabolism in many cell types and in vivo. In general, insulin or IGFs bind to insulin receptor (IR or IGF-I receptor (IGF-IR, activating the receptor tyrosine kinase. Insulin receptor substrates (IRSs are known to be major substrates of receptor kinases, mediating IGF/insulin signals to direct bioactivities. Recently, we discovered that IRSs form high-molecular-mass complexes (referred to here as IRSomes even without IGF/insulin stimulation. These complexes contain proteins (referred to here as IRSAP; IRS-associated protein, which modulate tyrosine phosphorylation of IRSs by receptor kinases, control IRS stability and determine intracellular localization of IRSs. In addition, in these complexes we found not only proteins that are involved in RNA metabolism but also RNAs themselves. Thus IRSAPs possibly contribute to modulation of IGF/insulin bioactivities. Since it is established that disorder of modulation of insulin-like activities causes various age-related diseases including cancer we could propose that the IRSome is an important target for treatment of these diseases.

  17. Parameters of activity of local and systemic inflammation in patients with bronchial asthma women without exacerbation of the disease

    Directory of Open Access Journals (Sweden)

    A. V. Barkova

    2016-01-01

    Full Text Available The study was conducted to evaluate the activity parameters of local and systemic inflammation in women suffering from bronchial asthma (BA. 119 women with asthma were studied, and 48 with a regular menstrual cycle and 71 in menopause; 38,7% of BA was mild, 61,3% – moderate severity. All patients were examined in the remission phase of the disease. On the background of normal values of conventional indicators of inflammation it was showed a significant increase of IL 1 alpha and IL 8 more in the group of women with regular menstrual cycles and normal body weight, IL1 alpha amounted to 489±80 pg/ml and IL8 – 631±122 pg/ml (p<0.05, which emphasizes the role of hormonal status of patients, and also the necessity of using the basic anti-inflammatory therapy during remission of BA.

  18. Dairy consumption and insulin resistance: the role of body fat, physical activity, and energy intake.

    Science.gov (United States)

    Tucker, Larry A; Erickson, Andrea; LeCheminant, James D; Bailey, Bruce W

    2015-01-01

    The relationship between dairy consumption and insulin resistance was ascertained in 272 middle-aged, nondiabetic women using a cross-sectional design. Participants kept 7-day, weighed food records to report their diets, including dairy intake. Insulin resistance was assessed using the homeostatic model assessment (HOMA). The Bod Pod was used to measure body fat percentage, and accelerometry for 7 days was used to objectively index physical activity. Regression analysis was used to determine the extent to which mean HOMA levels differed across low, moderate, and high dairy intake categories. Results showed that women in the highest quartile of dairy consumption had significantly greater log-transformed HOMA values (0.41 ± 0.53) than those in the middle-two quartiles (0.22 ± 0.55) or the lowest quartile (0.19 ± 0.58) (F = 6.90, P = 0.0091). The association remained significant after controlling for each potential confounder individually and all covariates simultaneously. Adjusting for differences in energy intake weakened the relationship most, but the association remained significant. Of the 11 potential confounders, only protein intake differed significantly across the dairy categories, with those consuming high dairy also consuming more total protein than their counterparts. Apparently, high dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.

  19. Dairy Consumption and Insulin Resistance: The Role of Body Fat, Physical Activity, and Energy Intake

    Directory of Open Access Journals (Sweden)

    Larry A. Tucker

    2015-01-01

    Full Text Available The relationship between dairy consumption and insulin resistance was ascertained in 272 middle-aged, nondiabetic women using a cross-sectional design. Participants kept 7-day, weighed food records to report their diets, including dairy intake. Insulin resistance was assessed using the homeostatic model assessment (HOMA. The Bod Pod was used to measure body fat percentage, and accelerometry for 7 days was used to objectively index physical activity. Regression analysis was used to determine the extent to which mean HOMA levels differed across low, moderate, and high dairy intake categories. Results showed that women in the highest quartile of dairy consumption had significantly greater log-transformed HOMA values (0.41 ± 0.53 than those in the middle-two quartiles (0.22 ± 0.55 or the lowest quartile (0.19 ± 0.58 (F = 6.90, P = 0.0091. The association remained significant after controlling for each potential confounder individually and all covariates simultaneously. Adjusting for differences in energy intake weakened the relationship most, but the association remained significant. Of the 11 potential confounders, only protein intake differed significantly across the dairy categories, with those consuming high dairy also consuming more total protein than their counterparts. Apparently, high dairy intake is a significant predictor of insulin resistance in middle-aged, nondiabetic women.

  20. Plasma glucose, insulin and catecholamine responses to a Wingate test in physically active women and men.

    Science.gov (United States)

    Vincent, Sophie; Berthon, Phanélie; Zouhal, Hassane; Moussa, Elie; Catheline, Michel; Bentué-Ferrer, Danièle; Gratas-Delamarche, Arlette

    2004-01-01

    The influence of gender on the glucose response to exercise remains contradictory. Moreover, to our knowledge, the glucoregulatory responses to anaerobic sprint exercise have only been studied in male subjects. Hence, the aim of the present study was to compare glucoregulatory metabolic (glucose and lactate) and hormonal (insulin, catecholamines and estradiol only in women) responses to a 30-s Wingate test, in physically active students. Eight women [19.8 (0.7) years] and eight men [22.0 (0.6) years] participated in a 30-s Wingate test on a bicycle ergometer. Plasma glucose, insulin, and catecholamine concentrations were determined at rest, at the end of both the warm-up and the exercise period and during the recovery (5, 10, 20, and 30 min). Results showed that the plasma glucose increase in response to a 30-s Wingate test was significantly higher in women than in men [0.99 (0.15) versus 0.33 (0.20) mmol l(-1) respectively, Pwomen than in men [14.7 (2.9) versus 2.3 (1.9) pmol l(-1) respectively, P<0.05]. However, there was no gender difference concerning the catecholamine response. The study indicates a gender-related difference in post-exercise plasma glucose and insulin responses after a supramaximal exercise.

  1. Physical activity and weight loss are independent predictors of improved insulin sensitivity following energy restriction.

    Science.gov (United States)

    Camps, Stefan G J A; Verhoef, Sanne P M; Westerterp, Klaas R

    2016-02-01

    The role of physical activity and the joint effect with sleep duration on insulin sensitivity (IS) during energy restriction followed by weight maintenance were determined. One hundred and two subjects (28 males) (mean ± SD age: 40 ± 9 years; BMI: 31.9 ± 3.0 kg/m(2) ) followed a very-low-energy diet for 8 weeks, followed by a 44-week period of weight maintenance. Body composition (three-compartment model based on body weight, total body water, and body volume), physical activity (accelerometry), sleep (questionnaire, Epworth Sleepiness Scale), and fasting plasma insulin and glucose concentrations were assessed before the diet and at 8, 20, and 52 weeks after the start. Compared to baseline, IS was improved significantly after 8 weeks (P physical activity counts. Maintaining daily physical activity during energy restriction is as important as weight loss itself in the improvement of IS; there was no additional effect of change in sleep duration. During weight maintenance, improved IS is maintained better if physical activity returns to baseline or higher. © 2016 The Obesity Society.

  2. Comparison of In Vivo Effects of Insulin on SREBP-1c Activation and INSIG-1/2 in Rat Liver and Human and Rat Adipose Tissue

    OpenAIRE

    Boden, Guenther; Salehi, Sajad; Cheung, Peter; Homko, Carol; Song, Weiwei; Loveland-Jones, Catherine; Jayarajan, Senthil

    2013-01-01

    The stimulatory effects of insulin on de novo lipogenesis (DNL) in the liver, where it is an important contributor to non-alcoholic fatty liver disease (NAFLD), hepatic and systemic insulin resistance, is strong and well established. In contrast, insulin plays only a minor role in DNL in adipose tissue. The reason why insulin stimulates DNL more in liver than in fat is not known but may be due to differential regulation of the transcription and post-translational activation of sterol regulato...

  3. Ablation of TSC2 enhances insulin secretion by increasing the number of mitochondria through activation of mTORC1.

    Directory of Open Access Journals (Sweden)

    Maki Koyanagi

    Full Text Available AIM: We previously found that chronic tuberous sclerosis protein 2 (TSC2 deletion induces activation of mammalian target of rapamycin Complex 1 (mTORC1 and leads to hypertrophy of pancreatic beta cells from pancreatic beta cell-specific TSC2 knockout (βTSC2(-/- mice. The present study examines the effects of TSC2 ablation on insulin secretion from pancreatic beta cells. METHODS: Isolated islets from βTSC2(-/- mice and TSC2 knockdown insulin 1 (INS-1 insulinoma cells treated with small interfering ribonucleic acid were used to investigate insulin secretion, ATP content and the expression of mitochondrial genes. RESULTS: Activation of mTORC1 increased mitochondrial DNA expression, mitochondrial density and ATP production in pancreatic beta cells of βTSC2(-/- mice. In TSC2 knockdown INS-1 cells, mitochondrial DNA expression, mitochondrial density and ATP production were increased compared with those in control INS-1 cells, consistent with the phenotype of βTSC2(-/- mice. TSC2 knockdown INS-1 cells also exhibited augmented insulin secretory response to glucose. Rapamycin inhibited mitochondrial DNA expression and ATP production as well as insulin secretion in response to glucose. Thus, βTSC2(-/- mice exhibit hyperinsulinemia due to an increase in the number of mitochondria as well as enlargement of individual beta cells via activation of mTORC1. CONCLUSION: Activation of mTORC1 by TSC2 ablation increases mitochondrial biogenesis and enhances insulin secretion from pancreatic beta cells.

  4. Activation of PPARα ameliorates hepatic insulin resistance and steatosis in high fructose-fed mice despite increased endoplasmic reticulum stress.

    Science.gov (United States)

    Chan, Stanley M H; Sun, Ruo-Qiong; Zeng, Xiao-Yi; Choong, Zi-Heng; Wang, Hao; Watt, Matthew J; Ye, Ji-Ming

    2013-06-01

    Endoplasmic reticulum (ER) stress is suggested to cause hepatic insulin resistance by increasing de novo lipogenesis (DNL) and directly interfering with insulin signaling through the activation of the c-Jun N-terminal kinase (JNK) and IκB kinase (IKK) pathway. The current study interrogated these two proposed mechanisms in a mouse model of hepatic insulin resistance induced by a high fructose (HFru) diet with the treatment of fenofibrate (FB) 100 mg/kg/day, a peroxisome proliferator-activated receptor α (PPARα) agonist known to reduce lipid accumulation while maintaining elevated DNL in the liver. FB administration completely corrected HFru-induced glucose intolerance, hepatic steatosis, and the impaired hepatic insulin signaling (pAkt and pGSK3β). Of note, both the IRE1/XBP1 and PERK/eIF2α arms of unfolded protein response (UPR) signaling were activated. While retaining the elevated DNL (indicated by the upregulation of SREBP1c, ACC, FAS, and SCD1 and [3H]H2O incorporation into lipids), FB treatment markedly increased fatty acid oxidation (indicated by induction of ACOX1, p-ACC, β-HAD activity, and [14C]palmitate oxidation) and eliminated the accumulation of diacylglycerols (DAGs), which is known to have an impact on insulin signaling. Despite the marked activation of UPR signaling, neither JNK nor IKK appeared to be activated. These findings suggest that lipid accumulation (mainly DAGs), rather than the activation of JNK or IKK, is pivotal for ER stress to cause hepatic insulin resistance. Therefore, by reducing the accumulation of deleterious lipids, activation of PPARα can ameliorate hepatic insulin resistance against increased ER stress.

  5. Analysis of Phosphatidylinositol 3-kinase Activation in the Adipose Tissue of Gestational Diabetes Mellitus Patients and Insulin Resistance

    Institute of Scientific and Technical Information of China (English)

    初永丽; 刘文娟; 崔青; 冯桂姣; 王彦; 姜学强

    2010-01-01

    The P85 regulatory subunit protein and gene expression and P110 catalylic subunit activity of phosphatidylinositol 3-kinase (PI-3K) were investigated in adipose tissue of patients with gestational diabetes mellitus (GDM) in order to explore the molecular mechanisms of insulin resistance (IR) of GDM. Samples from patients with GDM (n=50), and controls (n=50) were collected. Fasting insulin (FIN) was determined by radioimmunoassay. Fasting plasma glucose (FPG) was measured by oxidase assay. Western blot techn...

  6. Insulin resistance predicts early cardiovascular morbidity in men without diabetes mellitus, with effect modification by physical activity.

    Science.gov (United States)

    Hellgren, Margareta I; Daka, Bledar; Jansson, Per-Anders; Lindblad, Ulf; Larsson, Charlotte A

    2015-07-01

    to assess how well insulin resistance predicts cardiovascular disease (CVD) in non-diabetic men and women and to explore the influence of physical activity. in this prospective study 2563 men and women without diabetes were examined with an oral glucose tolerance test, anthropometric measurements and blood pressure assessment. Questionnaires about lifestyle and physical activity were completed. Insulin resistance was estimated by fasting concentrations of plasma insulin and by HOMA index for insulin resistance. Participants were followed up for cardiovascular morbidity and mortality during an 8-year period, using information from the National Swedish Inpatient and Mortality registers. at follow-up, HOMAir predicted CVD morbidity in males (50 events) and females (28 events) combined (HRage/sex-adj 1.4, 95% CI 1.1-1.7); however, when stratified by gender HOMAir was predictive solely in men (HRage-adj 1.8, 95% CI 1.3-2.4), whereas no association was found in women (HRage-adj 1.1, 95% CI 0.8-1.5). When stratifying the data for high and low physical activity, the predictive value of insulin resistance became stronger in sedentary men (HRage-adj 2.3, 95% CI 1.5-3.4) but was abolished in men performing moderate to vigorous physical activity (HRage-adj 1.0, 95% CI 0.6-1.6). The results remained when step-wise adjusted also for BMI, ApoB/ApoA1 and hypertension, as well as for smoking, alcohol consumption and education. Outcome for fasting plasma insulin was similar to HOMAir. insulin resistance predicts CVD in the general population; however, men may be more vulnerable to increased insulin resistance than women, and physically inactive men seem to be at high risk. © The European Society of Cardiology 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  7. Role of endosomal trafficking dynamics on the regulation of hepatic insulin receptor activity: models for Fao cells.

    Science.gov (United States)

    Hori, Sharon S; Kurland, Irwin J; DiStefano, Joseph J

    2006-05-01

    Evidence indicates that endosomal insulin receptor (IR) trafficking plays a role in regulating insulin signal transduction. To evaluate its importance, we developed a series of biokinetic models for quantifying activated surface and endosomal IR dynamics from published experimental data. Starting with a published two-compartment Fao hepatoma model, a four-pool model was formulated that depicts IR autophosphorylation after receptor binding, IR endosomal internalization/trafficking, insulin dissociation from and dephosphorylation of internalized IR, and recycling of unliganded, dephosphorylated IR to the plasma membrane. Quantification required three additional data sets, two measured, but unmodeled by the same group. A five-pool model created to include endosomal trafficking of the nonphosphorylated insulin-IR complex was fitted using the same data sets, augmented with another published data set. Creation of a six-pool model added the physiologically relevant dissociation of insulin ligand from the activated endosomal IR. More importantly, all three models, validated against additional data not used in model fitting, predict that, mechanistically, internalization of activated IR is a rate-limiting step, at least under the receptor saturating conditions of the fitting data. This rate includes the transit time to a site where insulin dissociation from and/or dephosphorylation of the IR occurs by docking with protein-tyrosine phosphatases (PTPases), or where a sufficient conformational change occurs in the IR, perhaps due to insulin-IR dissociation, where associated PTPases may complete IR dephosphorylation. Our new models indicate that key events in endosomal IR trafficking have significance in mediating IR activity, possibly serving to regulate insulin signal transduction.

  8. Management and prevention of exacerbations of COPD.

    Science.gov (United States)

    Aaron, Shawn D

    2014-09-22

    Patients with chronic obstructive pulmonary disease (COPD) are prone to acute respiratory exacerbations, which can develop suddenly or subacutely over the course of several days. Exacerbations have a detrimental effect on patients' health status and increase the burden on the healthcare system. Initial treatment is unsuccessful in 24-27% of patients, who have a relapse or a second exacerbation within 30 days of the initial event. No obvious benefit has been seen in recent clinical trials of anti-tumour necrosis factor therapy, anti-leukotriene therapy, intensive chest physiotherapy, or early inpatient pulmonary rehabilitation for treatment of exacerbations. By contrast, clinical trials of prevention rather than acute treatment have shown promising results. Long acting β agonist (LABA) or long acting anti-muscarinic (LAMA) bronchodilators and inhaled corticosteroid-LABA combinations prevent exacerbations in patients at risk, with relative risk reductions averaging 14-27% for each of these drugs relative to placebo. Triple therapy with inhaled corticosteroid-LABA plus LAMA may provide additional benefit, although study results to date are heterogeneous and more studies are needed. Pneumonia is an important complication of treatment with inhaled corticosteroid-LABA products, and the risk of pneumonia seems to be doubled in patients with COPD who use fluticasone. The addition of azithromycin to usual COPD therapy prevents exacerbations, although it may prolong the Q-T interval and increase the risk of death from cardiovascular disease in patients prone to arrhythmia. New potential drugs--including mitogen activated protein kinase inhibitors, phosphodiesterase 3 inhibitors, and monoclonal antibodies to the interleukin 1 receptor--offer additional hope for treatments that may prevent exacerbations in the future.

  9. Six-year change in youth physical activity and effect on fasting insulin and HOMA-IR.

    Science.gov (United States)

    Jago, Russell; Wedderkopp, Niels; Kristensen, Peter L; Møller, Niels C; Andersen, Lars B; Cooper, Ashley R; Froberg, Karsten

    2008-12-01

    There is a shortage of longitudinal data analyzing associations between physical activity and indicators of insulin resistance among children and adolescents after accounting for adiposity change. To guide future prevention efforts, data were used from the Danish arm of the European Youth Heart Study to examine these issues. Participants were 384 students in Grade 9 (aged 15 years) from the municipality of Odense, Denmark, who participated in surveys in 1997 and 2003. Physical activity was monitored for at least 3 days by accelerometer, and mean counts per minute (CPM) and minutes >3000 CPM per day were obtained. Blood samples were collected, and levels of fasting insulin, fasting glucose, and homeostasis model of assessment of insulin resistance (HOMA-IR) were obtained. Data were analyzed in 2008. Physical activity declined from 45 minutes >3000 CPM in 1997 to 35 minutes >3000 CPM in 2003. Longitudinal regression analyses showed that a change in minutes >3000 CPM was negatively associated with fasting insulin levels (z=-2.47, p=0.014) and HOMA-IR (z=-2.31, p=0.021) in 2003. Similar findings were found when CPM was used as the physical activity variable. Results demonstrated that a 6-year decline in physical activity was associated with higher insulin and HOMA-IR levels. The 6-year change in the volume of physical activity engaged in by adolescents aged 15 years was negatively associated with fasting insulin and HOMA-IR. Preventing an age-related decline in physical activity may be an effective means of preventing youth insulin resistance.

  10. Insulin analog with additional disulfide bond has increased stability and preserved activity

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Ribel, Ulla;

    2013-01-01

    bond may enhance insulin structural stability which would be highly desirable in a pharmaceutical use. To address this hypothesis, we designed insulin with an additional interchain disulfide bond in positions A10/B4 based on Cα-Cα distances, solvent exposure, and side-chain orientation in human insulin...... (HI) structure. This insulin analog had increased affinity for the insulin receptor and apparently augmented glucodynamic potency in a normal rat model compared with HI. Addition of the disulfide bond also resulted in a 34.6°C increase in melting temperature and prevented insulin fibril formation...... the classical insulin structure. Furthermore, the additional disulfide bond prevented this insulin analog from adopting the R-state conformation and thus showing that the R-state conformation is not a prerequisite for binding to insulin receptor as previously suggested. In summary, this is the first example...

  11. Structure Based Discovery of Small Molecules to Regulate the Activity of Human Insulin Degrading Enzyme

    OpenAIRE

    Bilal Çakir; Onur Dağliyan; Ezgi Dağyildiz; İbrahim Bariş; Ibrahim Halil Kavakli; Seda Kizilel; Metin Türkay

    2012-01-01

    Structure Based Discovery of Small Molecules to Regulate the Activity of Human Insulin Degrading Enzyme Bilal C¸ akir1, Onur Dag˘ liyan1, Ezgi Dag˘ yildiz1, I˙brahim Baris¸1, Ibrahim Halil Kavakli1,2*, Seda Kizilel1*, Metin Tu¨ rkay3* 1 Department of Chemical and Biological Engineering, Koc¸ University, Sariyer, Istanbul, Turkey, 2 Department of Molecular Biology and Genetics, Koc¸ University, Sariyer, Istanbul, Turkey, 3 Department of Industrial Engineering, Koc¸ University...

  12. Interleukin-1beta exacerbates and interleukin-1 receptor antagonist attenuates neuronal injury and microglial activation after excitotoxic damage in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Hailer, Nils P; Vogt, Cornelia; Korf, Horst-Werner; Dehghani, Faramarz

    2005-05-01

    The effects of interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1ra) on neurons and microglial cells were investigated in organotypic hippocampal slice cultures (OHSCs). OHSCs obtained from rats were excitotoxically lesioned after 6 days in vitro by application of N-methyl-D-aspartate (NMDA) and treated with IL-1beta (6 ng/mL) or IL-1ra (40, 100 or 500 ng/mL) for up to 10 days. OHSCs were then analysed by bright field microscopy after hematoxylin staining and confocal laser scanning microscopy after labeling of damaged neurons with propidium iodide (PI) and fluorescent staining of microglial cells. The specificity of PI labeling of damaged neurons was validated by triple staining with neuronal and glial markers and it was observed that PI accumulated in damaged neurons only but not in microglial cells or astrocytes. Treatment of unlesioned OHSCs with IL-1beta did not induce neuronal damage but caused an increase in the number of microglial cells. NMDA lesioning alone resulted in a massive increase in the number of microglial cells and degenerating neurons. Treatment of NMDA-lesioned OHSCs with IL-1beta exacerbated neuronal cell death and further enhanced microglial cell numbers. Treatment of NMDA-lesioned cultures with IL-1ra significantly attenuated NMDA-induced neuronal damage and reduced the number of microglial cells, whereas application of IL-1ra in unlesioned OHSCs did not induce significant changes in either cell population. Our findings indicate that: (i) IL-1beta directly affects the central nervous system and acts independently of infiltrating hematogenous cells; (ii) IL-1beta induces microglial activation but is not neurotoxic per se; (iii) IL-1beta enhances excitotoxic neuronal damage and microglial activation and (iv) IL-1ra, even when applied for only 4 h, reduces neuronal cell death and the number of microglial cells after excitotoxic damage.

  13. Somatostatin modulates insulin-degrading-enzyme metabolism: implications for the regulation of microglia activity in AD.

    Directory of Open Access Journals (Sweden)

    Grazia Tundo

    Full Text Available The deposition of β-amyloid (Aβ into senile plaques and the impairment of somatostatin-mediated neurotransmission are key pathological events in the onset of Alzheimer's disease (AD. Insulin-degrading-enzyme (IDE is one of the main extracellular protease targeting Aβ, and thus it represents an interesting pharmacological target for AD therapy. We show that the active form of somatostatin-14 regulates IDE activity by affecting its expression and secretion in microglia cells. A similar effect can also be observed when adding octreotide. Following a previous observation where somatostatin directly interacts with IDE, here we demonstrate that somatostatin regulates Aβ catabolism by modulating IDE proteolytic activity in IDE gene-silencing experiments. As a whole, these data indicate the relevant role played by somatostatin and, potentially, by analogue octreotide, in preventing Aβ accumulation by partially restoring IDE activity.

  14. Inhibition of human insulin gene transcription and MafA transcriptional activity by the dual leucine zipper kinase.

    Science.gov (United States)

    Stahnke, Marie-Jeannette; Dickel, Corinna; Schröder, Sabine; Kaiser, Diana; Blume, Roland; Stein, Roland; Pouponnot, Celio; Oetjen, Elke

    2014-09-01

    Insulin biosynthesis is an essential β-cell function and inappropriate insulin secretion and biosynthesis contribute to the pathogenesis of diabetes mellitus type 2. Previous studies showed that the dual leucine zipper kinase (DLK) induces β-cell apoptosis. Since β-cell dysfunction precedes β-cell loss, in the present study the effect of DLK on insulin gene transcription was investigated in the HIT-T15 β-cell line. Downregulation of endogenous DLK increased whereas overexpression of DLK decreased human insulin gene transcription. 5'- and 3'-deletion human insulin promoter analyses resulted in the identification of a DLK responsive element that mapped to the DNA binding-site for the β-cell specific transcription factor MafA. Overexpression of DLK wild-type but not its kinase-dead mutant inhibited MafA transcriptional activity conferred by its transactivation domain. Furthermore, in the non-β-cell line JEG DLK inhibited MafA overexpression-induced human insulin promoter activity. Overexpression of MafA and DLK or its kinase-dead mutant into JEG cells revealed that DLK but not its mutant reduced MafA protein content. Inhibition of the down-stream DLK kinase c-Jun N-terminal kinase (JNK) by SP600125 attenuated DLK-induced MafA loss. Furthermore, mutation of the serine 65 to alanine, shown to confer MafA protein stability, increased MafA-dependent insulin gene transcription and prevented DLK-induced MafA loss in JEG cells. These data suggest that DLK by activating JNK triggers the phosphorylation and degradation of MafA thereby attenuating insulin gene transcription. Given the importance of MafA for β-cell function, the inhibition of DLK might preserve β-cell function and ultimately retard the development of diabetes mellitus type 2.

  15. Extract of Polygala tenuifolia Alleviates Stress-Exacerbated Atopy-Like Skin Dermatitis through the Modulation of Protein Kinase A and p38 Mitogen-Activated Protein Kinase Signaling Pathway

    Science.gov (United States)

    Sur, Bongjun; Lee, Bombi; Yoon, Ye Seul; Lim, Pooreum; Hong, Riwon; Yeom, Mijung; Lee, Hyang Sook; Park, Hijoon; Shim, Insop; Lee, Hyejung; Jang, Young Pyo; Hahm, Dae-Hyun

    2017-01-01

    Atopic dermatitis (AD) and stress create a vicious cycle: stress exacerbates atopic symptoms, and atopic disease elicits stress and anxiety. Targeting multiple pathways including stress and allergic inflammation is, therefore, important for treating AD. In this study, we investigated the remedial value of Polygala tenuifolia Willd. (PTW) for treating immobilization (IMO) stress-exacerbated atopy-like skin dermatitis and its underlying mechanism. Trimellitic anhydride (TMA) was applied to dorsal skin for sensitization and subsequently both ears for eliciting T-cell-dependent contact hypersensitivity in mice, which underwent 2 h-IMO stress and PTW administration for the latter 6 and 9 days in the ear exposure period of TMA, respectively. To elicit in vitro degranulation of human mast cell line-1 (HMC-1), 10 µM substance P (SP) and 200 nM corticotrophin-releasing factor (CRF) were sequentially added with 48 h-interval. PTW extract (500 µg/mL) was added 30 min before CRF treatment. IMO stress exacerbated TMA-induced scratching behavior by 252%, and increased their blood corticosterone levels by two-fold. Treatment with 250 mg/kg PTW significantly restored IMO stress-exacerbated scratching behavior and other indicators such as skin inflammation and water content, lymph node weights, and serum histamine and immunoglobulin E (lgE) levels. Furthermore, it also reversed TMA-stimulated expression of tumor necrosis factor (TNF)-α and interleukin (IL)-4 mRNAs in ear tissues. PTW significantly inhibited SP/CRF-stimulated degranulation of HMC-1 cells, subsequent tryptase secretion, and protein kinase A (PKA) activity. PTW also selectively inhibited p38 mitogen-activated protein kinase (MAPK) phosphorylation in SP/CRF-treated HMC-1 cells. PTW significantly inhibited HMC-1 cell degranulation and alleviated IMO stress-exacerbated atopic dermatitis symptoms by modulating the PKA/p38 MAPK signaling pathway. PMID:28106783

  16. Extract of Polygala tenuifolia Alleviates Stress-Exacerbated Atopy-Like Skin Dermatitis through the Modulation of Protein Kinase A and p38 Mitogen-Activated Protein Kinase Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Bongjun Sur

    2017-01-01

    Full Text Available Atopic dermatitis (AD and stress create a vicious cycle: stress exacerbates atopic symptoms, and atopic disease elicits stress and anxiety. Targeting multiple pathways including stress and allergic inflammation is, therefore, important for treating AD. In this study, we investigated the remedial value of Polygala tenuifolia Willd. (PTW for treating immobilization (IMO stress-exacerbated atopy-like skin dermatitis and its underlying mechanism. Trimellitic anhydride (TMA was applied to dorsal skin for sensitization and subsequently both ears for eliciting T-cell-dependent contact hypersensitivity in mice, which underwent 2 h-IMO stress and PTW administration for the latter 6 and 9 days in the ear exposure period of TMA, respectively. To elicit in vitro degranulation of human mast cell line-1 (HMC-1, 10 µM substance P (SP and 200 nM corticotrophin-releasing factor (CRF were sequentially added with 48 h-interval. PTW extract (500 µg/mL was added 30 min before CRF treatment. IMO stress exacerbated TMA-induced scratching behavior by 252%, and increased their blood corticosterone levels by two-fold. Treatment with 250 mg/kg PTW significantly restored IMO stress-exacerbated scratching behavior and other indicators such as skin inflammation and water content, lymph node weights, and serum histamine and immunoglobulin E (lgE levels. Furthermore, it also reversed TMA-stimulated expression of tumor necrosis factor (TNF-α and interleukin (IL-4 mRNAs in ear tissues. PTW significantly inhibited SP/CRF-stimulated degranulation of HMC-1 cells, subsequent tryptase secretion, and protein kinase A (PKA activity. PTW also selectively inhibited p38 mitogen-activated protein kinase (MAPK phosphorylation in SP/CRF-treated HMC-1 cells. PTW significantly inhibited HMC-1 cell degranulation and alleviated IMO stress-exacerbated atopic dermatitis symptoms by modulating the PKA/p38 MAPK signaling pathway.

  17. Insulin sensitizers prevent fine particulate matter-induced vascular insulin resistance and changes in endothelial progenitor cell homeostasis.

    Science.gov (United States)

    Haberzettl, Petra; McCracken, James P; Bhatnagar, Aruni; Conklin, Daniel J

    2016-06-01

    Exposure to fine particular matter (PM2.5) increases the risk of developing cardiovascular disease and Type 2 diabetes. Because blood vessels are sensitive targets of air pollutant exposure, we examined the effects of concentrated ambient PM2.5 (CAP) on vascular insulin sensitivity and circulating levels of endothelial progenitor cells (EPCs), which reflect cardiovascular health. We found that CAP exposure for 9 days decreased insulin-stimulated Akt phosphorylation in the aorta of mice maintained on control diet. This change was accompanied by the induction of IL-1β and increases in the abundance of cleaved IL-18 and p10 subunit of Casp-1, consistent with the activation of the inflammasome pathway. CAP exposure also suppressed circulating levels of EPCs (Flk-1(+)/Sca-1(+) cells), while enhancing the bone marrow abundance of these cells. Although similar changes in vascular insulin signaling and EPC levels were observed in mice fed high-fat diet, CAP exposure did not exacerbate diet-induced changes in vascular insulin resistance or EPC homeostasis. Treatment with an insulin sensitizer, metformin or rosiglitazone, prevented CAP-induced vascular insulin resistance and NF-κB and inflammasome activation and restored peripheral blood and bone marrow EPC levels. These findings suggest that PM2.5 exposure induces diet-independent vascular insulin resistance and inflammation and prevents EPC mobilization, and that this EPC mobilization defect could be mediated by vascular insulin resistance. Impaired vascular insulin sensitivity may be an important mechanism underlying PM2.5-induced vascular injury, and pharmacological sensitization to insulin action could potentially prevent deficits in vascular repair and mitigate vascular inflammation due to exposure to elevated levels of ambient air pollution. Copyright © 2016 the American Physiological Society.

  18. Obesity and insulin resistance are associated with reduced activity in core memory regions of the brain.

    Science.gov (United States)

    Cheke, Lucy G; Bonnici, Heidi M; Clayton, Nicola S; Simons, Jon S

    2017-02-01

    Increasing research in animals and humans suggests that obesity may be associated with learning and memory deficits, and in particular with reductions in episodic memory. Rodent models have implicated the hippocampus in obesity-related memory impairments, but the neural mechanisms underlying episodic memory deficits in obese humans remain undetermined. In the present study, lean and obese human participants were scanned using fMRI while completing a What-Where-When episodic memory test (the "Treasure-Hunt Task") that assessed the ability to remember integrated item, spatial, and temporal details of previously encoded complex events. In lean participants, the Treasure-Hunt task elicited significant activity in regions of the brain known to be important for recollecting episodic memories, such as the hippocampus, angular gyrus, and dorsolateral prefrontal cortex. Both obesity and insulin resistance were associated with significantly reduced functional activity throughout the core recollection network. These findings indicate that obesity is associated with reduced functional activity in core brain areas supporting episodic memory and that insulin resistance may be a key player in this association. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Insulin-degrading enzyme is activated by the C-terminus of α-synuclein.

    Science.gov (United States)

    Sharma, Sandeep K; Chorell, Erik; Wittung-Stafshede, Pernilla

    2015-10-16

    The insulin-degrading enzyme (IDE) plays a key role in type-2 diabetes and typically degrades small peptides such as insulin, amyloid β and islet amyloid polypeptide. We recently reported a novel non-proteolytical interaction in vitro between IDE and the Parkinson's disease 140-residue protein α-synuclein that resulted in dual effects: arrested α-synuclein oligomers and, simultaneously, increased IDE proteolysis activity. Here we demonstrate that these outcomes arise due to IDE interactions with the C-terminus of α-synuclein. Whereas a peptide containing the first 97 residues of α-synuclein did not improve IDE activity and its aggregation was not blocked by IDE, a peptide with the C-terminal 44 residues of α-synuclein increased IDE proteolysis to the same degree as full-length α-synuclein. Because the α-synuclein C-terminus is acidic, the interaction appears to involve electrostatic attraction with IDE's basic exosite, known to be involved in activation.

  20. [Effect of a two-week program of individually monitored physical activity on insulin resistance in obese non-insulin-dependent diabetics].

    Science.gov (United States)

    Cizmić, Milica; Zivotić-Vanović, Mirjana; Zivanić, Slobodan; Dragojević, Radosav

    2003-01-01

    It is well known that under the influence of regular, individually measured aerobic physical activity, it is possible to raise the biological efficiency of insulin by several mechanisms: by increasing the number of insulin receptors, their sensitivity and efficiency, as well as by increasing glucose transporters GLUT-4 on the level of cell membrane. The aim of this research was to examine whether decreased insulin resistance could be achieved under the influence of the program of individually measured aerobic physical activity in the 2-week period, in the obese type 2 diabetes patients with the increased aerobic capacity (VO2)max. In 10 type 2 diabetes patients 47.6 +/- 4.6 years of age (group E), in the 14-days period, program of aerobic training was applied (10 sessions--35 min session of walking on treadmill, intensity 60.8 +/- 5.7% (VO2)max, frequency 5 times a week), as well as 1,600 kcal diet. At the same time, other 10 type 2 diabetes patients 45.9 +/- 5.5 years of age (group C) were on 1,600 kcal diet. Before and after this period the following was measured in both groups: insulin sensitivity (M/I) by the method of hyperinsulin euglycemic clamp, and (VO2)max by Astrand test on ergocycle. In contrast to the group C, in the second testing of E group subjects a significant increase was obtained in M/I (1.23 +/- 0.78 vs. 2.42 +/- 0.95 mg/kg/min/mU p VO2)max (26.34 +/- 4.26 vs. 29.16 +/- 5.01 ml/kg/min p tested patients.

  1. Insulin secretion enhancing activity of roselle calyx extract in normal and streptozotocin-induced diabetic rats

    Directory of Open Access Journals (Sweden)

    Eamruthai Wisetmuen

    2013-01-01

    Full Text Available Background and Objective: Our recent study revealed the antihyperglycemic activity of an ethanolic extract of roselle calyxes (Hibiscus sabdariffa in diabetic rats. The present study had, therefore, an objective to investigate the mechanism underlying this activity. Materials and Methods: Male Sprague Dawley rats were induced to be diabetes by intraperitoneal injection of 45 mg/kg streptozotocin (STZ. Normal rats as well as diabetic rats were administered with the ethanolic extract of H. sabdariffa calyxes (HS-EE at 0.1 and 1.0 g/kg/day, respectively, for 6 weeks. Then, blood glucose and insulin levels, at basal and glucose-stimulated secretions, were measured. The pancreas was dissected to examine histologically. Results: HS-EE 1.0 g/kg/day significantly decreased the blood glucose level by 38 ± 12% in diabetic rats but not in normal rats. In normal rats, treatment with 1.0 g/kg HS-EE increased the basal insulin level significantly as compared with control normal rats (1.28 ± 0.25 and 0.55 ± 0.05 ng/ml, respectively. Interestingly, diabetic rats treated with 1.0 g/kg HS-EE also showed a significant increase in basal insulin level as compared with the control diabetic rats (0.30 ± 0.05 and 0.15 ± 0.01 ng/ml, respectively. Concerning microscopic histological examination, HS-EE 1.0 g/kg significantly increased the number of islets of Langerhans in both normal rats (1.2 ± 0.1 and 2.0 ± 0.1 islet number/10 low-power fields (LPF for control and HS-EE treated group, respectively and diabetic rats (1.0 ± 0.3 and 3.9 ± 0.6 islet number/10 LPF for control and HS-EE treated group, respectively. Conclusion: The antidiabetic activity of HS-EE may be partially mediated via the stimulating effect on insulin secretion.

  2. Substitution of isoleucine for methionine at position 1153 in the beta-subunit of the human insulin receptor. A mutation that impairs receptor tyrosine kinase activity, receptor endocytosis, and insulin action.

    Science.gov (United States)

    Cama, A; Quon, M J; de la Luz Sierra, M; Taylor, S I

    1992-04-25

    The intracellular domain of the insulin receptor possesses activity as a tyrosine-specific protein kinase. The receptor tyrosine kinase is stimulated by insulin binding to the extracellular domain of the receptor. Previously, we have identified a patient with a genetic form of insulin resistance who is heterozygous for a mutation substituting Ile for Met1153 in the tyrosine kinase domain of the receptor near the cluster of the three major autophosphorylation sites (Tyr1158, Tyr1162, and Tyr1163). In this investigation, the Ile1153 mutant receptor was expressed by transfection of mutant cDNA into NIH-3T3 cells. The mutation impairs receptor tyrosine kinase activity and also inhibits the ability of insulin to stimulate 2-deoxyglucose uptake and thymidine incorporation. These data support the hypothesis that the receptor tyrosine activity plays a necessary role in the ability of the receptor to mediate insulin action in vivo. Furthermore, expression of the Ile1153 mutant receptor exerted a dominant negative effect to inhibit the ability of endogenous murine receptors for insulin and insulin-like growth factor I to mediate their actions upon the cell. This observation is consistent with previous suggestions that mutant receptors dimerize with wild type receptors, thereby creating hybrid molecules which lack biological activity. The dominant negative effect of the mutant receptor may explain the dominant mode of inheritance of insulin resistance caused by the Ile1153 mutation. Finally, the mutation inhibits the ability of insulin to stimulate receptor endocytosis. This may explain the normal number of insulin receptors on the surface of the patient's cells in vivo. Despite the presence of markedly elevated levels of insulin in the patient's plasma, the receptors were resistant to down-regulation.

  3. Involvement of tristetraprolin in transcriptional activation of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase by insulin

    Energy Technology Data Exchange (ETDEWEB)

    Ness, Gene C., E-mail: gness@hsc.usf.edu [Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612 (United States); Edelman, Jeffrey L.; Brooks, Patricia A. [Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612 (United States)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer siRNAs to tristetraprolin blocks transcription of HMGR in vivo in rat liver. Black-Right-Pointing-Pointer siRNAs to tristetraprolin inhibits insulin activation of HMGR transcription. Black-Right-Pointing-Pointer Insulin acts to rapidly increase tristetraprolin in liver nuclear extracts. -- Abstract: Several AU-rich RNA binding element (ARE) proteins were investigated for their possible effects on transcription of hepatic 3-hydroxy-3-methyglutaryl coenzyme A reductase (HMGR) in normal rats. Using in vivo electroporation, four different siRNAs to each ARE protein were introduced together with HMGR promoter (-325 to +20) luciferase construct and compared to saline controls. All four siRNAs to tristetraprolin (TTP) completely eliminated transcription from the HMGR promoter construct. Since insulin acts to rapidly increase hepatic HMGR transcription, the effect of TTP siRNA on induction by insulin was tested. The 3-fold stimulation by insulin was eliminated by this treatment. In comparison, siRNA to AU RNA binding protein/enoyl coenzyme A hydratase (AUH) had no effect. These findings indicate a role for TTP in the insulin-mediated activation of hepatic HMGR transcription.

  4. Impact of exacerbations on COPD

    Directory of Open Access Journals (Sweden)

    A. Anzueto

    2010-06-01

    Full Text Available Exacerbations of chronic obstructive pulmonary disease (COPD determine disease-associated morbidity, mortality, resource burden and healthcare costs. Acute exacerbation care requirements range from unscheduled primary care visits to emergency room, inpatient or intensive care, generating significant costs in COPD. Even after an exacerbation resolves, respiratory, physical, social and emotional impairment may persist for prolonged time. Frequent exacerbations, mainly in patients with severe COPD, accelerate disease progression and mortality. Thus, patients with frequent exacerbations have a more rapid decline in lung function, worse quality of life and decreased exercise performance. Management of COPD directed to reduce incidence and severity of exacerbations improves long-term health status and conserves health care resources and costs.

  5. Insulin improves cardiomyocyte contractile function through enhancement of SERCA2a activity in simulated ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Jie YU; Hai-feng ZHANG; Feng WU; Qiu-xia LI; Heng MA; Wen-yi GUO; Hai-chang WANG; Feng GAO

    2006-01-01

    Aim: Insulin exerts anti-apoptotic effects in both cardiomyocytes and coronary endothelial cells following ischemia/reperfusion (I/R) via the Akt-endothelial nitric oxide synthase survival signal pathway. This important insulin signaling might further contribute to the improvement of cardiac function after reperfusion. In this study, we tested the hypothesis that sarcoplasmic reticulum calcium-AT-Pase (SERCA2a) is involved in the insulin-induced improvement of cardiac contractile function following I/R. Methods: Ventricular myocytes were enzymatically isolated from adult SD rats. Simulated I/R was induced by perfusing cells with chemical anoxic solution for 15 min followed by reperfusion with Tyrode's solution with or without insulin for 30 min. Myocyte shortening and intracellular calcium transients were assessed and underlying mechanisms were investigated. Results: Reperfusion with insulin (10-7 mol/L) significantly improved the recovery of contractile function (n=15-20 myocytes from 6-8 hearts, P<0.05), and increased calcium transients, as evidenced by the increased calcium (Ca2+) fluorescence ratio, shortened time to peak Ca2+ and time to 50% diastolic Ca2+, compared with those in cells reperfused with vehicle (P<0.05). In addition, Akt phosphorylation and SERCA2a activity were both increased in insulin-treated I/R cardiomyocytes, which were markedly inhibited by pretreatment of cells with a specific Akt inhibitor. Moreover, inhibition of Akt activity abolished insulin-induced positive contractile and calcium transients responses in I/R cardiomyocytes. Conclusion: These data demonstrated for the first time that insulin improves the recovery of contractile function in simulated I/R cardiomyocytes in an Akt-dependent and SERCA2a-mediated fashion.

  6. Implications of compound heterozygous insulin receptor mutations in congenital muscle fibre type disproportion myopathy for the receptor kinase activation

    DEFF Research Database (Denmark)

    Klein, H H; Müller, R; Vestergaard, H

    1999-01-01

    % of the receptors to become insulin-dependently activated. The mother carries a point mutation at the last base pair in exon 17 which, due to abnormal alternative splicing, could lead to normally transcribed receptor or truncated receptor lacking the kinase region. Kinase activation was normal in the mother......We studied insulin receptor kinase activation in two brothers with congenital muscle fibre type disproportion myopathy and compound heterozygous mutations of the insulin receptor gene, their parents, and their unaffected brother. In the father who has a heterozygote Arg1174-->Gln mutation, in situ......'s skeletal muscle, suggesting that virtually no truncated receptor was expressed. Receptor kinase activity was, however, reduced by 95 and 91% in the compound heterozygous brothers. This suggests that the mother's mutated allele contributes little to the generation of functional receptor protein...

  7. THE ROLE OF PHYSICAL ACTIVITY IN THE PRIMARY PREVENTION OF TYPE 2 DIABETES VIA THE AMELIORATION OF INSULIN RESISTANCE

    Directory of Open Access Journals (Sweden)

    Ash C. Routen

    2010-08-01

    Full Text Available Type 2 diabetes is the most common endocrine disease in our society, affecting around 5% of Western populations, whilst showing a steady rise in prevalence. The complications that arise from the disease are known to cause morbidity and mortality, and are associated with long-term damage, dysfunction, and failure of variousorgans. These complications include atherosclerosis in the micro and macro vasculature, kidney dysfunction, nerve problems, hypertension; and eye problems such as retinopathy. Epidemiological evidence suggests regular physical activity improves insulin sensitivity. This review presents the case for physical activity as a tool ofprimary prevention, in the population of non-diabetics and high risk individuals (IFG & IGT, in reference to obesity related insulin resistance. Cross-sectional, prospective cohort and randomised control trials clearly show that moderate-intensity physical activity can improve insulin sensitivity; this can be improved further byundertaking vigorous-intensity physical activity.

  8. Alteration in insulin action

    DEFF Research Database (Denmark)

    Tanti, J F; Gual, P; Grémeaux, T

    2004-01-01

    Insulin resistance, when combined with impaired insulin secretion, contributes to the development of type 2 diabetes. Insulin resistance is characterised by a decrease in insulin effect on glucose transport in muscle and adipose tIssue. Tyrosine phosphorylation of insulin receptor substrate 1 (IRS......-1) and its binding to phosphatidylinositol 3-kinase (PI 3-kinase) are critical events in the insulin signalling cascade leading to insulin-stimulated glucose transport. Modification of IRS-1 by serine phosphorylation could be one of the mechanisms leading to a decrease in IRS-1 tyrosine...... to phosphorylate these serine residues have been identified. These exciting results suggest that serine phosphorylation of IRS-1 is a possible hallmark of insulin resistance in biologically insulin responsive cells or tIssues. Identifying the pathways by which "diabetogenic" factors activate IRS-1 kinases...

  9. Peroxisome proliferator-activated receptor gamma agonists as insulin sensitizers: from the discovery to recent progress.

    Science.gov (United States)

    Cho, Nobuo; Momose, Yu

    2008-01-01

    An epidemic of metabolic diseases including type 2 diabetes and obesity is undermining the health of people living in industrialized societies. There is an urgent need to develop innovative therapeutics. The peroxisome proliferator-activated receptor gamma (PPARgamma) is one of the ligand-activated transcription factors in the nuclear hormone receptor superfamily and a pivotal regulator of glucose and lipid homeostasis. The discovery of PPARgamma as a target of multimodal insulin sensitizers, represented by thiazolidinediones (TZDs), has attracted remarkable scientific interest and had a great impact on the pharmaceutical industry. With the clinical success of the PPARgamma agonists, pioglitazone (Actos) and rosiglitazone (Avandia), development of novel and potent insulin-sensitizing agents with diverse clinical profiles has been accelerated. Currently, a number of PPARgamma agonists from different chemical classes and with varying pharmacological profiles are being developed. Despite quite a few obstacles to the development of PPAR-related drugs, PPARgamma-targeted agents still hold promise. There are new concepts and encouraging evidence emerging that suggest this class can yield improved anti-diabetic agents. This review covers the discovery of TZDs, provides an overview of PPARgamma including the significance of PPARgamma as a drug target, describes the current status of a wide variety of novel PPARgamma ligands including PPAR dual and pan agonists and selective PPARgamma modulators (SPPARgammaMs), and highlights new approaches for identifying agents targeting PPARgamma in the treatment of type 2 diabetes.

  10. Studies on the mechanism of insulin resistance in the liver from humans with noninsulin-dependent diabetes. Insulin action and binding in isolated hepatocytes, insulin receptor structure, and kinase activity.

    OpenAIRE

    Caro, J F; Ittoop, O; Pories, W J; Meelheim, D; Flickinger, E G; Thomas, F; Jenquin, M; Silverman, J F; Khazanie, P G; Sinha, M. K.

    1986-01-01

    We have developed a method to isolate insulin-responsive human hepatocytes from an intraoperative liver biopsy to study insulin action and resistance in man. Hepatocytes from obese patients with noninsulin-dependent diabetes were resistant to maximal insulin concentration, and those from obese controls to submaximal insulin concentration in comparison to nonobese controls. Insulin binding per cell number was similar in all groups. However, insulin binding per surface area was decreased in the...

  11. Insulin-increased L-arginine transport requires A(2A adenosine receptors activation in human umbilical vein endothelium.

    Directory of Open Access Journals (Sweden)

    Enrique Guzmán-Gutiérrez

    Full Text Available Adenosine causes vasodilation of human placenta vasculature by increasing the transport of arginine via cationic amino acid transporters 1 (hCAT-1. This process involves the activation of A(2A adenosine receptors (A(2AAR in human umbilical vein endothelial cells (HUVECs. Insulin increases hCAT-1 activity and expression in HUVECs, and A(2AAR stimulation increases insulin sensitivity in subjects with insulin resistance. However, whether A(2AAR plays a role in insulin-mediated increase in L-arginine transport in HUVECs is unknown. To determine this, we first assayed the kinetics of saturable L-arginine transport (1 minute, 37°C in the absence or presence of nitrobenzylthioinosine (NBTI, 10 µmol/L, adenosine transport inhibitor and/or adenosine receptors agonist/antagonists. We also determined hCAT-1 protein and mRNA expression levels (Western blots and quantitative PCR, and SLC7A1 (for hCAT-1 reporter promoter activity. Insulin and NBTI increased the extracellular adenosine concentration, the maximal velocity for L-arginine transport without altering the apparent K(m for L-arginine transport, hCAT-1 protein and mRNA expression levels, and SLC7A1 transcriptional activity. An A2AAR antagonist ZM-241385 blocked these effects. ZM241385 inhibited SLC7A1 reporter transcriptional activity to the same extent in cells transfected with pGL3-hCAT-1(-1606 or pGL3-hCAT-1(-650 constructs in the presence of NBTI + insulin. However, SLC7A1 reporter activity was increased by NBTI only in cells transfected with pGL3-hCAT-1(-1606, and the ZM-241385 sensitive fraction of the NBTI response was similar in the absence or in the presence of insulin. Thus, insulin modulation of hCAT-1 expression and activity requires functional A(2AAR in HUVECs, a mechanism that may be applicable to diseases associated with fetal insulin resistance, such as gestational diabetes.

  12. Bioluminescence imaging of β cells and intrahepatic insulin gene activity under normal and pathological conditions.

    Directory of Open Access Journals (Sweden)

    Tokio Katsumata

    Full Text Available In diabetes research, bioluminescence imaging (BLI has been applied in studies of β-cell impairment, development, and islet transplantation. To develop a mouse model that enables noninvasive imaging of β cells, we generated a bacterial artificial chromosome (BAC transgenic mouse in which a mouse 200-kbp genomic fragment comprising the insulin I gene drives luciferase expression (Ins1-luc BAC transgenic mouse. BLI of mice was performed using the IVIS Spectrum system after intraperitoneal injection of luciferin, and the bioluminescence signal from the pancreatic region analyzed. When compared with MIP-Luc-VU mice [FVB/N-Tg(Ins1-lucVUPwrs/J] expressing luciferase under the control of the 9.2-kbp mouse insulin I promoter (MIP, the bioluminescence emission from Ins1-luc BAC transgenic mice was enhanced approximately 4-fold. Streptozotocin-treated Ins1-luc BAC transgenic mice developed severe diabetes concomitant with a sharp decline in the BLI signal intensity in the pancreas. Conversely, mice fed a high-fat diet for 8 weeks showed an increase in the signal, reflecting a decrease or increase in the β-cell mass. Although the bioluminescence intensity of the islets correlated well with the number of isolated islets in vitro, the intensity obtained from a living mouse in vivo did not necessarily reflect an absolute quantification of the β-cell mass under pathological conditions. On the other hand, adenovirus-mediated gene transduction of β-cell-related transcription factors in Ins1-luc BAC transgenic mice generated luminescence from the hepatic region for more than 1 week. These results demonstrate that BLI in Ins1-luc BAC transgenic mice provides a noninvasive method of imaging islet β cells and extrapancreatic activity of the insulin gene in the liver under normal and pathological conditions.

  13. 25-hydroxyvitamin D deficiency, exacerbation frequency and human rhinovirus exacerbations in chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Quint Jennifer K

    2012-06-01

    Full Text Available Abstract Background 25-hydroxyvitamin D deficiency is associated with COPD and increased susceptibility to infection in the general population. Methods We investigated whether COPD patients deficient in 25-hydroxyvitamin D were more likely to be frequent exacerbators, had reduced outdoor activity and were more susceptible to human rhinovirus (HRV exacerbations than those with insufficient and normal levels. We also investigated whether the frequency of FokI, BsmI and TaqIα 25-hydroxyvitamin D receptor (VDR polymorphisms differed between frequent and infrequent exacerbators. Results There was no difference in 25-hydroxyvitamin D levels between frequent and infrequent exacerbators in the summer; medians 44.1nmol/L (29.1 – 68.0 and 39.4nmol/L (22.3 – 59.2 or winter; medians 24.9nmol/L (14.3 – 43.1 and 27.1nmol/L (19.9 – 37.6. Patients who spent less time outdoors in the 14 days prior to sampling had lower 25-hydroxyvitamin D levels (p = 0.02. Day length was independently associated with 25-hydroxyvitamin D levels (p = 0.02. There was no difference in 25-hydroxyvitamin D levels between baseline and exacerbation; medians 36.2nmol/L (IQR 22.4-59.4 and 33.3nmol/L (23.0-49.7; p = 0.43. HRV positive exacerbations were not associated with lower 25-hydroxyvitamin D levels at exacerbation than exacerbations that did not test positive for HRV; medians 30.0nmol/L (20.4 – 57.8 and 30.6nmol/L (19.4 – 48.7. There was no relationship between exacerbation frequency and any VDR polymorphisms (all p > 0.05. Conclusions Low 25-hydroxyvitamin D levels in COPD are not associated with frequent exacerbations and do not increase susceptibility to HRV exacerbations. Independent of day length, patients who spend less time outdoors have lower 25-hydroxyvitamin D concentration.

  14. The effects of two-week program of individually measured physical activity on insulin resistance in obese non-insulin-dependent diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Čizmić Milica

    2003-01-01

    Full Text Available It is well known that under the influence of regular, individually measured aerobic physical activity, it is possible to raise the biological efficiency of insulin by several mechanisms: by increasing the number of insulin receptors, their sensitivity and efficiency, as well as by increasing glucose transporters GLUT-4 on the level of cell membrane. The aim of this research was to examine whether decreased insulin resistance could be achieved under the influence of the program of individually measured aerobic physical activity in the 2-week period, in the obese type 2 diabetes patients with the increased aerobic capacity (VO2max. In 10 type 2 diabetes patients 47.6 ± 4.6 years of age (group E, in the 14-days period, program of aerobic training was applied (10 sessions - 35 min session of walking on treadmill, intensity 60.8 ± 5.7% (VO2max, frequency 5 times a week , as well as 1 600 kcal diet. At the same time, other 10 type 2 diabetes patients 45.9 ± 5.5 years of age (group C were on 1 600 kcal diet. Before and after this period the following was measured in both groups: insulin sensitivity (M/I by the method of hyperinsulin euglycemic clamp, and (VO2max by Astrand test on ergocycle. In contrast to the group C, in the second testing of E group subjects a significant increase was obtained in M/I (1.23 ± 0.78 vs. 2.42 ± 0.95 mg/kg/min/mU p<0.001, 96.75% as well as the increase of (VO2max (26.34 ± 4.26 vs. 29.16 ± 5.01 ml/kg/min p<0.05, 10.7%. The results had shown that 2-week program of aerobic training had had significant influence on the increased aerobic capacity and insulin sensitivity in the tested patients.

  15. Mechanisms linking brain insulin resistance to Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Maria Niures P.S. Matioli

    Full Text Available Several studies have indicated that Diabetes Mellitus (DM can increase the risk of developing Alzheimer's disease (AD. This review briefly describes current concepts in mechanisms linking DM and insulin resistance/deficiency to AD. Insulin/insulin-like growth factor (IGF resistance can contribute to neurodegeneration by several mechanisms which involve: energy and metabolism deficits, impairment of Glucose transporter-4 function, oxidative and endoplasmic reticulum stress, mitochondrial dysfunction, accumulation of AGEs, ROS and RNS with increased production of neuro-inflammation and activation of pro-apoptosis cascade. Impairment in insulin receptor function and increased expression and activation of insulin-degrading enzyme (IDE have also been described. These processes compromise neuronal and glial function, with a reduction in neurotransmitter homeostasis. Insulin/IGF resistance causes the accumulation of AβPP-Aβ oligomeric fibrils or insoluble larger aggregated fibrils in the form of plaques that are neurotoxic. Additionally, there is production and accumulation of hyper-phosphorylated insoluble fibrillar tau which can exacerbate cytoskeletal collapse and synaptic disconnection.

  16. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic {beta} cells

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Mirshahi, Faridoddin [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Grider, John R. [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Murthy, Karnam S., E-mail: skarnam@vcu.edu [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Sanyal, Arun J., E-mail: asanyal@mcvh-vcu.edu [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer G protein coupled receptor TGR5 is expressed in mouse and human islets. Black-Right-Pointing-Pointer TGR5 is coupled to activation of Gs and Ca{sup 2+} release via cAMP/Epac/PLC-{epsilon} pathway. Black-Right-Pointing-Pointer Activation of TGR5 by bile salts and selective ligands causes insulin secretion. Black-Right-Pointing-Pointer TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic {beta} cells. In the present study, we have identified the expression of TGR5 in pancreatic {beta} cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated G{alpha}{sub s} and caused an increase in intracellular cAMP and Ca{sup 2+}. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective G{alpha}{sub s} inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on G{sub s}/cAMP/Ca{sup 2+} pathway. 8-pCPT-2 Prime -O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic {beta} cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  17. Myocardial autophagy activation and suppressed survival signaling is associated with insulin resistance in fructose-fed mice.

    Science.gov (United States)

    Mellor, Kimberley M; Bell, James R; Young, Morag J; Ritchie, Rebecca H; Delbridge, Lea M D

    2011-06-01

    Fructose intake is linked with the increasing prevalence of insulin resistance and there is now evidence for a specific insulin-resistant cardiomyopathy. The aim of this study was to determine the cardiac-specific myocardial remodeling effects of high fructose dietary intake. Given the links between insulin signaling, reactive oxygen species generation and autophagy induction, we hypothesized that autophagy contributes to pathologic remodeling in the insulin-resistant heart, and in particular may be a feature of high fructose diet-induced cardiac phenotype. Male C57Bl/6 mice were fed a high fructose (60%) diet or nutrient-matched control diet for 12 weeks. Systemic and myocardial insulin-resistant status was characterized. Superoxide production (lucigenin) and cellular growth and death signaling pathways were examined in myocardial tissue. Myocardial structural remodeling was evaluated by measurement of heart weight indices and histological analysis of collagen deposition (picrosirius red). Fructose-fed mice exhibited hyperglycemia and glucose intolerance, but plasma insulin and blood pressure were unchanged. High fructose intake suppressed the myocardial Akt cell survival signaling coincident with increased cardiac superoxide generation (21% increase, pFructose feeding induced elevated autophagy (LC3B-II: LC3B-I ratio: 46% increase, pfructose-fed mice. We provide the first evidence that myocardial autophagy activation is associated with systemic insulin resistance, and that high level fructose intake inflicts direct cardiac damage. Upregulated autophagy is associated with elevated cardiac superoxide production, suppressed cell survival signaling and fibrotic infiltration in fructose-fed mice. The novel finding that autophagy contributes to cardiac pathology in insulin resistance identifies a new therapeutic target for diabetic cardiomyopathy.

  18. Proteasome Activity Is Affected by Fluctuations in Insulin-Degrading Enzyme Distribution.

    Science.gov (United States)

    Sbardella, Diego; Tundo, Grazia Raffaella; Sciandra, Francesca; Bozzi, Manuela; Gioia, Magda; Ciaccio, Chiara; Tarantino, Umberto; Brancaccio, Andrea; Coletta, Massimo; Marini, Stefano

    2015-01-01

    Insulin-Degrading-Enzyme (IDE) is a Zn2+-dependent peptidase highly conserved throughout evolution and ubiquitously distributed in mammalian tissues wherein it displays a prevalent cytosolic localization. We have recently demonstrated a novel Heat Shock Protein-like behaviour of IDE and its association with the 26S proteasome. In the present study, we examine the mechanistic and molecular features of IDE-26S proteasome interaction in a cell experimental model, extending the investigation also to the effect of IDE on the enzymatic activities of the 26S proteasome. Further, kinetic investigations indicate that the 26S proteasome activity undergoes a functional modulation by IDE through an extra-catalytic mechanism. The IDE-26S proteasome interaction was analyzed during the Heat Shock Response and we report novel findings on IDE intracellular distribution that might be of critical relevance for cell metabolism.

  19. Proteasome Activity Is Affected by Fluctuations in Insulin-Degrading Enzyme Distribution.

    Directory of Open Access Journals (Sweden)

    Diego Sbardella

    Full Text Available Insulin-Degrading-Enzyme (IDE is a Zn2+-dependent peptidase highly conserved throughout evolution and ubiquitously distributed in mammalian tissues wherein it displays a prevalent cytosolic localization. We have recently demonstrated a novel Heat Shock Protein-like behaviour of IDE and its association with the 26S proteasome. In the present study, we examine the mechanistic and molecular features of IDE-26S proteasome interaction in a cell experimental model, extending the investigation also to the effect of IDE on the enzymatic activities of the 26S proteasome. Further, kinetic investigations indicate that the 26S proteasome activity undergoes a functional modulation by IDE through an extra-catalytic mechanism. The IDE-26S proteasome interaction was analyzed during the Heat Shock Response and we report novel findings on IDE intracellular distribution that might be of critical relevance for cell metabolism.

  20. A sesquiterpene quinone, dysidine, from the sponge Dysidea villosa, activates the insulin pathway through inhibition of PTPases

    Institute of Scientific and Technical Information of China (English)

    Yu ZHANG; Yan LI; Yue-wei GUO; Hua-liang JIANG; Xu SHEN

    2009-01-01

    Aim: The sesquiterpene hydroquinones/quinones belong to one class of marine sponge metabolites, and they have Accepted considerable attention due to their varied biological activities, including anti-tumor, anti-HIV, and anti-inflammatory action. In order to probe the potential anti-diabetic effect of the sesquiterpene hydroquinones/quinones, the effect of dysi-dine on the insulin pathway was studied.Methods: The promotion of glucose uptake by dysidine was studied in differentiated 3T3-L1 cells. The increase in membrane-located GLUT4 by dysidine was studied in CHO-K1/GLUT4 and 3T3-L1 cells by immuno-staining. The activation of the insulin signaling pathway by dysidine was probed by Western blotting. The inhibition of PTPases by dysidine was detected in vitro.Results: Dysidine, found in the Hainan sponge Dysidea villosa in the Chinese South Sea, effectively activated the insulin signaling pathway, greatly promoted glucose uptake in 3T3-L1 ceils, and showed strong insulin-sensitizing activities. The potential targets of action for dysidine were probed, and the results indicated that dysidine exhibited its cellular effects through activation of the insulin pathway, possibly through the inhibition of protein tyrosine phosphatases, with more specific inhibition against protein tyrosine phosphatase 1B (PTPIB). Conclusion: Our findings are expected to expand understanding of the biological activities of sesquiterpene hydroquino-nes/quinones, and they show that dysidine could be a potential lead compound in the development of an alternative adju-vant in insulin therapy.

  1. Palmitoleic acid prevents palmitic acid-induced macrophage activation and consequent p38 MAPK-mediated skeletal muscle insulin resistance.

    Science.gov (United States)

    Talbot, Nicola A; Wheeler-Jones, Caroline P; Cleasby, Mark E

    2014-08-05

    Obesity and saturated fatty acid (SFA) treatment are both associated with skeletal muscle insulin resistance (IR) and increased macrophage infiltration. However, the relative effects of SFA and unsaturated fatty acid (UFA)-activated macrophages on muscle are unknown. Here, macrophages were treated with palmitic acid, palmitoleic acid or both and the effects of the conditioned medium (CM) on C2C12 myotubes investigated. CM from palmitic acid-treated J774s (palm-mac-CM) impaired insulin signalling and insulin-stimulated glycogen synthesis, reduced Inhibitor κBα and increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase in myotubes. p38 MAPK inhibition or siRNA partially ameliorated these defects, as did addition of tumour necrosis factor-α blocking antibody to the CM. Macrophages incubated with both FAs generated CM that did not induce IR, while palmitoleic acid-mac-CM alone was insulin sensitising. Thus UFAs may improve muscle insulin sensitivity and counteract SFA-mediated IR through an effect on macrophage activation.

  2. Regulation of liver glucokinase activity in rats with fructose-induced insulin resistance and impaired glucose and lipid metabolism.

    Science.gov (United States)

    Francini, Flavio; Castro, María C; Gagliardino, Juan J; Massa, María L

    2009-09-01

    We evaluated the relative role of different regulatory mechanisms, particularly 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFK2/FBPase-2), in liver glucokinase (GK) activity in intact animals with fructose-induced insulin resistance and impaired glucose and lipid metabolism. We measured blood glucose, triglyceride and insulin concentration, glucose tolerance, liver triglyceride content, GK activity, and GK and PFK2 protein and gene expression in fructose-rich diet (FRD) and control rats. After 3 weeks, FRD rats had significantly higher blood glucose, insulin and triglyceride levels, and liver triglyceride content, insulin resistance, and impaired glucose tolerance. FRD rats also had significantly higher GK activity in the cytosolic fraction (18.3 +/- 0.35 vs. 11.27 +/- 0.34 mU/mg protein). Differences in GK protein concentration (116% and 100%) were not significant, suggesting a potentially impaired GK translocation in FRD rats. Although GK transcription level was similar, PFK2 gene expression and protein concentration were 4- and 5-fold higher in the cytosolic fraction of FRD animals. PFK2 immunological blockage significantly decreased GK activity in control and FRD rats; in the latter, this blockage decreased GK activity to control levels. Results suggest that increased liver GK activity might participate in the adaptative response to fructose overload to maintain glucose/triglyceride homeostasis in intact animals. Under these conditions, PFK2 increase would be the main enhancer of GK activity.

  3. Time-dependent regulation of muscle caveolin activation and insulin signalling in response to high-fat diet.

    Science.gov (United States)

    Gómez-Ruiz, Ana; de Miguel, Carlos; Campión, Javier; Martínez, J Alfredo; Milagro, Fermín I

    2009-10-06

    We studied the effect of high-fat diet on the expression and activation of the three caveolins in rat skeletal muscle and their association with the insulin signalling cascade. Initial response was characterized by increased signalling through Cav-1 and Cav-3 phosphorylation, suggesting that both participate in an initial acute response to the calorie surplus. Afterwards, Cav-1 signalling was slightly reduced, whereas Cav-3 remained active. Late chronic phase signalling through both proteins was impaired inducing a prediabetic state. Summarizing, caveolins seem to mediate a time-dependent regulation of insulin cascade in response to high-fat diet in muscle.

  4. Small-molecule activators of insulin-degrading enzyme discovered through high-throughput compound screening.

    Directory of Open Access Journals (Sweden)

    Christelle Cabrol

    Full Text Available BACKGROUND: Hypocatabolism of the amyloid beta-protein (Abeta by insulin-degrading enzyme (IDE is implicated in the pathogenesis of Alzheimer disease (AD, making pharmacological activation of IDE an attractive therapeutic strategy. However, it has not been established whether the proteolytic activity of IDE can be enhanced by drug-like compounds. METHODOLOGY/PRINCIPAL FINDINGS: Based on the finding that ATP and other nucleotide polyphosphates modulate IDE activity at physiological concentrations, we conducted parallel high-throughput screening campaigns in the absence or presence of ATP and identified two compounds--designated Ia1 and Ia2--that significantly stimulate IDE proteolytic activity. Both compounds were found to interfere with the crosslinking of a photoaffinity ATP analogue to IDE, suggesting that they interact with a bona fide ATP-binding domain within IDE. Unexpectedly, we observed highly synergistic activation effects when the activity of Ia1 or Ia2 was tested in the presence of ATP, a finding that has implications for the mechanisms underlying ATP-mediated activation of IDE. Notably, Ia1 and Ia2 activated the degradation of Abeta by approximately 700% and approximately 400%, respectively, albeit only when Abeta was presented in a mixture also containing shorter substrates. CONCLUSIONS/SIGNIFICANCE: This study describes the first examples of synthetic small-molecule activators of IDE, showing that pharmacological activation of this important protease with drug-like compounds is achievable. These novel activators help to establish the putative ATP-binding domain as a key modulator of IDE proteolytic activity and offer new insights into the modulatory action of ATP. Several larger lessons abstracted from this screen will help inform the design of future screening campaigns and facilitate the eventual development of IDE activators with therapeutic utility.

  5. Insulin Secretagogues

    Science.gov (United States)

    ... Your Body in Balance › Insulin Secretagogues Fact Sheet Insulin Secretagogues March, 2012 Download PDFs English Espanol Editors ... medicines can help you stay healthy. What are insulin secretagogues? Insulin secretagogues (pronounced seh-KREET-ah-gogs) ...

  6. Luteolin reduces obesity-associated insulin resistance in mice by activating AMPKα1 signalling in adipose tissue macrophages.

    Science.gov (United States)

    Zhang, Lei; Han, Yi-Jing; Zhang, Xian; Wang, Xin; Bao, Bin; Qu, Wei; Liu, Jian

    2016-10-01

    Inflammatory polarisation of adipose tissue macrophages (ATMs) plays a critical role in the development of obesity-associated metabolic diseases such as insulin resistance and diabetes. Our previous study indicated that dietary luteolin (LU) could prevent the establishment of insulin resistance in mice fed a high-fat diet (HFD). Here, we further investigated the effects of LU, which is a natural flavonoid, on pre-established insulin resistance and obesity-associated ATM polarisation in mice. Five-week-old C57/BL6 mice were fed on a low-fat diet or HFD for 20 weeks, with some mice receiving supplementation with 0.01% LU from weeks 1 or 10 of the HFD to assess the actions of LU on insulin resistance and ATM polarisation. Furthermore, the role of LU in metabolic-dysfunction-associated macrophage phenotypes was investigated in vitro. Dietary LU supplementation, either for 20 weeks or from weeks 10 to 20 of an HFD, significantly improved insulin resistance in HFD-fed mice. In addition, inflammatory macrophage infiltration and polarisation were suppressed in mouse epididymal adipose tissues. Furthermore, LU treatment directly reversed lipopolysaccharide-stimulated and metabolism-regulated molecules, and induced inflammatory polarisation in mouse RAW264.7 cells and peritoneal cavity resident macrophages. Finally, using the selective AMP-activated protein kinase (AMPK) inhibitor compound C and Ampkα1 (also known as Prkaa1) silencing with siRNA, we found that LU activated AMPKα1 in macrophages to inhibit their inflammatory polarisation and enhanced insulin signals in adipocytes that were stimulated with macrophage-conditioned media. Dietary LU ameliorated insulin resistance in diet-induced obese mice by promoting AMPKα1 signalling in ATMs.

  7. Insulin relaxes bladder via PI3K/AKT/eNOS pathway activation in mucosa: unfolded protein response-dependent insulin resistance as a cause of obesity-associated overactive bladder

    Science.gov (United States)

    Leiria, Luiz O; Sollon, Carolina; Báu, Fernando R; Mónica, Fabíola Z; D’Ancona, Carlos L; De Nucci, Gilberto; Grant, Andrew D; Anhê, Gabriel F; Antunes, Edson

    2013-01-01

    We aimed to investigate the role of insulin in the bladder and its relevance for the development of overactive bladder (OAB) in insulin-resistant obese mice. Bladders from male individuals who were involved in multiple organ donations were used. C57BL6/J mice were fed with a high-fat diet for 10 weeks to induce insulin-resistant obesity. Concentration–response curves to insulin were performed in human and mouse isolated mucosa-intact and mucosa-denuded bladders. Cystometric study was performed in terminally anaesthetized mice. Western blot was performed in bladders to detect phosphorylated endothelial NO synthase (eNOS) (Ser1177) and the phosphorylated protein kinase AKT (Ser473), as well as the unfolded protein response (UPR) markers TRIB3, CHOP and ATF4. Insulin (1–100 nm) produced concentration-dependent mouse and human bladder relaxations that were markedly reduced by mucosal removal or inhibition of the PI3K/AKT/eNOS pathway. In mouse bladders, insulin produced a 3.0-fold increase in cGMP levels (P insulin-induced phosphorylation of AKT and eNOS in bladder mucosa. Obese mice showed greater voiding frequency and non-voiding contractions, indicating overactive detrusor smooth muscle. Insulin failed to relax the bladder or to increase cGMP in the obese group. Insulin-stimulated AKT and eNOS phosphorylation in mucosa was also impaired in obese mice. The UPR markers TRIB3, CHOP and ATF4 were increased in the mucosa of obese mice. The UPR inhibitor 4-phenyl butyric acid normalized all the functional and molecular parameters in obese mice. Our data show that insulin relaxes human and mouse bladder via activation of the PI3K/AKT/eNOS pathway in the bladder mucosa. Endoplasmic reticulum stress-dependent insulin resistance in bladder contributes to OAB in obese mice. PMID:23478138

  8. Association of leisure time physical activity and abdominal obesity with fasting serum insulin and 2-h postchallenge plasma glucose levels.

    Science.gov (United States)

    Borodulin, K; Tuomilehto, J; Peltonen, M; Lakka, T A; Sundvall, J; Jousilahti, P

    2006-09-01

    We investigated the joint associations of leisure time physical activity and abdominal obesity with fasting insulin and 2-h glucose levels and with the risk of impaired glucose tolerance (IGT) and Type 2 diabetes (Type 2 DM). A cross-sectional population-based random sample of 1812 Finnish adults 45-74 years of age without a history of cardiovascular disease or diabetes. Relative energy expenditure during the previous 12 months (METh/week), assessed by a questionnaire, was used as a measure of leisure time physical activity. Waist-hip ratio (WHR) was used as a measure of abdominal obesity. IGT and Type 2 DM were assessed by a 2-h oral glucose tolerance test and were defined according to the World Health Organization guidelines. While 2-h glucose and fasting insulin levels increased with increasing WHR (P physical activity (P = 0.015 and P fasting insulin levels were found among individuals who had most abdominal obesity and were least physically active. Physically inactive individuals had a higher prevalence of IGT and Type 2 DM in all WHR tertiles than physically active persons. Higher levels of leisure time physical activity are associated with lower 2-h glucose and fasting insulin levels and a reduced risk of having IGT and Type 2 DM, independent of the level of abdominal obesity.

  9. Hepatic glycogen supercompensation activates AMP-activated protein kinase, impairs insulin signaling, and reduces glycogen deposition in the liver.

    Science.gov (United States)

    Winnick, Jason J; An, Zhibo; Ramnanan, Christopher J; Smith, Marta; Irimia, Jose M; Neal, Doss W; Moore, Mary Courtney; Roach, Peter J; Cherrington, Alan D

    2011-02-01

    The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver's ability to take up and metabolize glucose. During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO(2)) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P vs. 100 ± 3 mg/g; P fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU.

  10. Activation of the adenosine A2A receptor exacerbates experimental autoimmune neuritis in Lewis rats in association with enhanced humoral immunity.

    Science.gov (United States)

    Zhang, Min; Li, Xiao-Li; Li, Heng; Wang, Shan; Wang, Cong-Cong; Yue, Long-Tao; Xu, Hua; Zhang, Peng; Chen, Hui; Yang, Bing; Duan, Rui-Sheng

    2016-04-15

    Accumulated evidence demonstrated that Adenosine A2A receptor (A2AR) is involved in the inflammatory diseases. In the present study, we showed that a selective A2AR agonist, CGS21680, exacerbated experimental autoimmune neuritis in Lewis rats induced with bovine peripheral myelin. The exacerbation was accompanied with reduced CD4(+)Foxp3(+) T cells, increased CD4(+)CXCR5(+) T cells, B cells, dendritic cells and antigen-specific autoantibodies, which is possibly due to the inhibition of IL-2 induced by CGS21680. Combined with previous studies, our data indicate that the effects of A2AR stimulation in vivo are variable in different diseases. Caution should be taken in the use of A2AR agonists.

  11. Insulin and Insulin Resistance

    OpenAIRE

    Wilcox, Gisela

    2005-01-01

    As obesity and diabetes reach epidemic proportions in the developed world, the role of insulin resistance and its consequences are gaining prominence. Understanding the role of insulin in wide-ranging physiological processes and the influences on its synthesis and secretion, alongside its actions from the molecular to the whole body level, has significant implications for much chronic disease seen in Westernised populations today. This review provides an overview of insulin, its history, stru...

  12. Glucose administration inhibits the hepatic activation of gluconeogenesis promoted by insulin-induced hypoglycemia

    Directory of Open Access Journals (Sweden)

    Sharize Betoni Galende

    2009-08-01

    Full Text Available The activation of hepatic gluconeogenesis in male Wistar adult 6 h fasted rats during insulin-induced hypoglycemia (IIH was previously demonstrated. In this study, the effects of intraperitoneal (ip glucose (100 mg/kg on the activation of liver gluconeogenesis during IIH was investigated. Thus, 6 h fasted rats that received ip regular insulin (1 U/kg and 30 min later ip saline (Control group or glucose (Experimental group were compared. All the experiments were executed 60 min after insulin injection. The glycemia of Control and Experimental groups were not different (P > 0.05. To investigate gluconeogenesis, liver perfusion experiments were performed. The results demonstrated that excepting glycerol, livers from rats which received ip glucose showed lower (P Em estudo recente empregando ratos Wistar com 6 h de privação alimentar demonstramos que ocorre ativação da neoglicogênese hepática durante a hipoglicemia induzida por insulina (HII. Neste estudo, os efeitos da administração intraperitoneal (ip de glicose (100 mg/kg sobre a ativação da neoglicogênese hepática durante a HII foi investigada. Assim, ratos com 6 h de privação alimentar que receberam insulina regular ip (1 U/kg e 30 min depois salina (Grupo Controle ou glicose ip (Grupo Experimental foram comparados. Os experimentos foram executados 60 min após a injeção de insulina. A glicemia dos grupos Controle e Experimental não foi diferente (P > 0.05. Para investigar a neoglicogênese, realizouse experimentos de perfusão de fígado. Os resultados demonstraram, exceto para o glicerol, que fígados de ratos que receberam glicose ip (Grupo Experimental, apresentaram menor taxa (P < 0.05 de neoglicogênese a partir de L-alanina, Lglutamina, L-lactato ou L-alanina + L-glutamina + L-lactato + glicerol. Portanto, a ausência de recuperação da glicemia após administração de glicose foi mediada por inibição da neoglicogênese hepática.

  13. Activation of PPARd and RXRa stimulates fatty acid oxidatin and insulin secretion inpancreatic beta-cells

    DEFF Research Database (Denmark)

    Børgesen, Michael; Ravnskjær, Kim; Frigerio, Francesca;

    ACTIVATION OF PPARd AND RXRa STIMULATES FATTY ACID OXIDATION AND INSULIN SECRETION IN PANCREATIC b-CELLS Michael Boergesen1, Kim Ravnskjaer2, Francesca Frigerio3, Allan E. Karlsen4, Pierre Maechler3 and Susanne Mandrup1 1 Department of Biochemistry and Molecular Biology, University of Southern...... oxidation and dissipation of lipids particularly in skeletal muscle. Here we show that PPARd at the RNA as well as protein level is the most abundant PPAR subtype in the rat pancreatic ß-cell line INS-1E and in isolated rat pancreatic islets. In keeping with that, a large number of PPAR target genes...... involved in fatty acid uptake and oxidation. This correlates with a 5-fold induction of 14C-Oleate ß-oxidation when INS-1E cells are exposed to PPARd and RXR agonists. Notably, culture of INS-1E cells with oleate and other unsaturated fatty acids in the presence of an RXR agonist induces the same subset...

  14. Chronic inhibition of 11 β -hydroxysteroid dehydrogenase type 1 activity decreases hypertension, insulin resistance, and hypertriglyceridemia in metabolic syndrome.

    Science.gov (United States)

    Schnackenberg, Christine G; Costell, Melissa H; Krosky, Daniel J; Cui, Jianqi; Wu, Charlene W; Hong, Victor S; Harpel, Mark R; Willette, Robert N; Yue, Tian-Li

    2013-01-01

    Metabolic syndrome is a constellation of risk factors including hypertension, dyslipidemia, insulin resistance, and obesity that promote the development of cardiovascular disease. Metabolic syndrome has been associated with changes in the secretion or metabolism of glucocorticoids, which have important functions in adipose, liver, kidney, and vasculature. Tissue concentrations of the active glucocorticoid cortisol are controlled by the conversion of cortisone to cortisol by 11 β -hydroxysteroid dehydrogenase type 1 (11 β -HSD1). Because of the various cardiovascular and metabolic activities of glucocorticoids, we tested the hypothesis that 11 β -HSD1 is a common mechanism in the hypertension, dyslipidemia, and insulin resistance in metabolic syndrome. In obese and lean SHR/NDmcr-cp (SHR-cp), cardiovascular, metabolic, and renal functions were measured before and during four weeks of administration of vehicle or compound 11 (10 mg/kg/d), a selective inhibitor of 11 β -HSD1. Compound 11 significantly decreased 11 β -HSD1 activity in adipose tissue and liver of SHR-cp. In obese SHR-cp, compound 11 significantly decreased mean arterial pressure, glucose intolerance, insulin resistance, hypertriglyceridemia, and plasma renin activity with no effect on heart rate, body weight gain, or microalbuminuria. These results suggest that 11 β -HSD1 activity in liver and adipose tissue is a common mediator of hypertension, hypertriglyceridemia, glucose intolerance, and insulin resistance in metabolic syndrome.

  15. Chronic Inhibition of 11β-Hydroxysteroid Dehydrogenase Type 1 Activity Decreases Hypertension, Insulin Resistance, and Hypertriglyceridemia in Metabolic Syndrome

    Directory of Open Access Journals (Sweden)

    Christine G. Schnackenberg

    2013-01-01

    Full Text Available Metabolic syndrome is a constellation of risk factors including hypertension, dyslipidemia, insulin resistance, and obesity that promote the development of cardiovascular disease. Metabolic syndrome has been associated with changes in the secretion or metabolism of glucocorticoids, which have important functions in adipose, liver, kidney, and vasculature. Tissue concentrations of the active glucocorticoid cortisol are controlled by the conversion of cortisone to cortisol by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1. Because of the various cardiovascular and metabolic activities of glucocorticoids, we tested the hypothesis that 11β-HSD1 is a common mechanism in the hypertension, dyslipidemia, and insulin resistance in metabolic syndrome. In obese and lean SHR/NDmcr-cp (SHR-cp, cardiovascular, metabolic, and renal functions were measured before and during four weeks of administration of vehicle or compound 11 (10 mg/kg/d, a selective inhibitor of 11β-HSD1. Compound 11 significantly decreased 11β-HSD1 activity in adipose tissue and liver of SHR-cp. In obese SHR-cp, compound 11 significantly decreased mean arterial pressure, glucose intolerance, insulin resistance, hypertriglyceridemia, and plasma renin activity with no effect on heart rate, body weight gain, or microalbuminuria. These results suggest that 11β-HSD1 activity in liver and adipose tissue is a common mediator of hypertension, hypertriglyceridemia, glucose intolerance, and insulin resistance in metabolic syndrome.

  16. Angiotensin II inhibits insulin-stimulated GLUT4 translocation and Akt activation through tyrosine nitration-dependent mechanisms.

    Directory of Open Access Journals (Sweden)

    Alfredo Csibi

    Full Text Available Angiotensin II (Ang II plays a major role in the pathogenesis of insulin resistance and diabetes by inhibiting insulin's metabolic and potentiating its trophic effects. Whereas the precise mechanisms involved remain ill-defined, they appear to be associated with and dependent upon increased oxidative stress. We found Ang II to block insulin-dependent GLUT4 translocation in L6 myotubes in an NO- and O(2(*--dependent fashion suggesting the involvement of peroxynitrite. This hypothesis was confirmed by the ability of Ang II to induce tyrosine nitration of the MAP kinases ERK1/2 and of protein kinase B/Akt (Akt. Tyrosine nitration of ERK1/2 was required for their phosphorylation on Thr and Tyr and their subsequent activation, whereas it completely inhibited Akt phosphorylation on Ser(473 and Thr(308 as well as its activity. The inhibitory effect of nitration on Akt activity was confirmed by the ability of SIN-1 to completely block GSK3alpha phosphorylation in vitro. Inhibition of nitric oxide synthase and NAD(PHoxidase and scavenging of free radicals with myricetin restored insulin-stimulated Akt phosphorylation and GLUT4 translocation in the presence of Ang II. Similar restoration was obtained by inhibiting the ERK activating kinase MEK, indicating that these kinases regulate Akt activation. We found a conserved nitration site of ERK1/2 to be located in their kinase domain on Tyr(156/139, close to their active site Asp(166/149, in agreement with a permissive function of nitration for their activation. Taken together, our data show that Ang II inhibits insulin-mediated GLUT4 translocation in this skeletal muscle model through at least two pathways: first through the transient activation of ERK1/2 which inhibit IRS-1/2 and second through a direct inhibitory nitration of Akt. These observations indicate that not only oxidative but also nitrative stress play a key role in the pathogenesis of insulin resistance. They underline the role of protein

  17. Physical activity energy expenditure is associated with 2-h insulin independently of obesity among Inuit in Greenland.

    Science.gov (United States)

    Dahl-Petersen, Inger Katrine; Bjerregaard, Peter; Brage, Søren; Jørgensen, Marit Eika

    2013-12-01

    Indigenous populations throughout the Arctic are experiencing a rapid increase in the prevalence of obesity and type 2 diabetes. The role of physical activity in relation to glucose metabolism in Arctic populations is not well studied. We examined the association between objectively measured physical activity energy expenditure (PAEE) and glucose metabolism in a population-based study of adult Inuit in Greenland. Cross-sectional data were collected by combined accelerometry and heart rate monitoring (ACC+HR) among Inuit (18+ years) in Greenland during 2005-2010 (n=1545). PAEE was calculated and the associations with fasting glucose, 2-h glucose, fasting insulin, 2-h insulin concentrations and body composition were analysed by linear regression. An inverse association between PAEE and fasting insulin, 2-h insulin, 2-h glucose, fat percentage, BMI and waist circumference (WC) was found after adjustments by age and sex. Only the association between PAEE and 2-h insulin remained significant after adjustment by WC (P=0.01), most pronounced at low levels of PAEE indicating a threshold around 35-40kJ/kg/day. No overall linear trend was found for fasting glucose and 2-h glucose. This population-based study showed that PAEE was associated with 2-h insulin independently of obesity in an inverse dose-response relation. Insufficient physical activity may contribute to impaired glucose tolerance through a pathway including alterations in obesity and fat distribution. Both obesity and low levels of PAEE may be important contributing risk factors for the increasing prevalence of type 2 diabetes mellitus among Inuit in Greenland, but additional risk factors should be examined in this indigenous population. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  18. Direct angiotensin II type 2 receptor stimulation ameliorates insulin resistance in type 2 diabetes mice with PPARγ activation.

    Directory of Open Access Journals (Sweden)

    Kousei Ohshima

    Full Text Available OBJECTIVES: The role of angiotensin II type 2 (AT(2 receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT(2 receptor stimulation by compound 21 (C21 might contribute to possible insulin-sensitizing/anti-diabetic effects in type 2 diabetes (T2DM with PPARγ activation, mainly focusing on adipose tissue. METHODS: T2DM mice, KK-Ay, were subjected to intraperitoneal injection of C21 and/or a PPARγ antagonist, GW9662 in drinking water for 2 weeks. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[(3H] deoxy-D-glucose in white adipose tissue. Morphological changes of adipose tissues as well as adipocyte differentiation and inflammatory response were examined. RESULTS: Treatment with C21 ameliorated insulin resistance in KK-Ay mice without influencing blood pressure, at least partially through effects on the PPARγ pathway. C21 treatment increased serum adiponectin concentration and decreased TNF-α concentration; however, these effects were attenuated by PPARγ blockade by co-treatment with GW9662. Moreover, we observed that administration of C21 enhanced adipocyte differentiation and PPARγ DNA-binding activity, with a decrease in inflammation in white adipose tissue, whereas these effects of C21 were attenuated by co-treatment with GW9662. We also observed that administration of C21 restored β cell damage in diabetic pancreatic tissue. CONCLUSION: The present study demonstrated that direct AT(2 receptor stimulation by C21 accompanied with PPARγ activation ameliorated insulin resistance in T2DM mice, at least partially due to improvement of adipocyte dysfunction and protection of pancreatic β cells.

  19. Electroacupuncture-Induced Cholinergic Nerve Activation Enhances the Hypoglycemic Effect of Exogenous Insulin in a Rat Model of Streptozotocin-Induced Diabetes

    Directory of Open Access Journals (Sweden)

    Yu-Chen Lee

    2011-01-01

    Full Text Available The aim of this study is to explore the mechanisms by which electroacupuncture (EA enhances the hypoglycemic effect of exogenous insulin in a streptozotocin- (STZ- diabetic rats. Animals in the EA group were anesthetized and subjected to the insulin challenge test (ICT and EA for 60 minutes. In the control group, rats were subjected to the same treatment with the exception of EA stimulation. Blood samples were drawn to measure changes in plasma glucose, free fatty acids (FFA, and insulin levels. Western blot was used to assay proteins involved in insulin signaling. Furthermore, atropine, hemicholinium-3 (HC-3, and Eserine were used to explore the relationship between EA and cholinergic nerve activation during ICT. EA augmented the blood glucose-lowering effects of EA by activating the cholinergic nerves in STZ rats that had been exposed to exogenous insulin. This phenomenon may be related to enhancement of insulin signaling rather than to changes in FFA concentration.

  20. Circulating insulin stimulates fatty acid retention in white adipose tissue via KATP channel activation in the central nervous System only in insulin-sensitive mice

    NARCIS (Netherlands)

    Coomans, C.P.; Geerling, J.J.; Guigas, B.; Hoek, A.M. van den; Parlevliet, E.T.; Ouwens, D.M.; Pijl, H.; Voshol, P.J.; Rensen, P.C.N.; Havekes, L.M.; Romijn, J.A.

    2011-01-01

    Insulin signaling in the central nervous system (CNS) is required for the inhibitory effect of insulin on glucose production. Our aim was to determine whether the CNS is also involved in the stimulatory effect of circulating insulin on the tissue-specific retention of fatty acid (FA) from plasma. In

  1. Circulating insulin stimulates fatty acid retention in white adipose tissue via KATP channel activation in the central nervous System only in insulin-sensitive mice

    NARCIS (Netherlands)

    Coomans, C.P.; Geerling, J.J.; Guigas, B.; Hoek, A.M. van den; Parlevliet, E.T.; Ouwens, D.M.; Pijl, H.; Voshol, P.J.; Rensen, P.C.N.; Havekes, L.M.; Romijn, J.A.

    2011-01-01

    Insulin signaling in the central nervous system (CNS) is required for the inhibitory effect of insulin on glucose production. Our aim was to determine whether the CNS is also involved in the stimulatory effect of circulating insulin on the tissue-specific retention of fatty acid (FA) from plasma. In

  2. Hypochlorous acid via peroxynitrite activates protein kinase Cθ and insulin resistance in adipocytes

    OpenAIRE

    Zhou, Jun; Wang, Qilong; Ding, Ye; Zou, Ming-hui

    2015-01-01

    We recently reported that genetic deletion of myeloperoxidase (MPO) alleviates obesity-related insulin resistance in mice in vivo. How MPO impairs insulin sensitivity in adipocytes is poorly characterized. As hypochlorous acid (HOCl) is a principal oxidant product generated by MPO, we evaluated the effects of HOCl on insulin signaling in adipocytes differentiated from 3T3-L1 cells. Exposure of 3T3-L1 adipocytes to exogenous HOCl (200 μmol/l) attenuated insulin-stimulated 2-deoxyglucose uptake...

  3. Insulin sensitive and resistant obesity in humans: AMPK activity, oxidative stress, and depot-specific changes in gene expression in adipose tissue[S

    Science.gov (United States)

    Xu, X. Julia; Gauthier, Marie-Soleil; Hess, Donald T.; Apovian, Caroline M.; Cacicedo, Jose M.; Gokce, Noyan; Farb, Melissa; Valentine, Rudy J.; Ruderman, Neil B.

    2012-01-01

    We previously reported that adenosine monophosphate-activated protein kinase (AMPK) activity is lower in adipose tissue of morbidly obese individuals who are insulin resistant than in comparably obese people who are insulin sensitive. However, the number of patients and parameters studied were small. Here, we compared abdominal subcutaneous, epiploic, and omental fat from 16 morbidly obese individuals classified as insulin sensitive or insulin resistant based on the homeostatic model assessment of insulin resistance. We confirmed that AMPK activity is diminished in the insulin resistant group. A custom PCR array revealed increases in mRNA levels of a wide variety of genes associated with inflammation and decreases in PGC-1α and Nampt in omental fat of the insulin resistant group. In contrast, subcutaneous abdominal fat of the same patients showed increases in PTP-1b, VEGFa, IFNγ, PAI-1, and NOS-2 not observed in omental fat. Only angiotensinogen and CD4+ mRNA levels were increased in both depots. Surprisingly, TNFα was only increased in epiploic fat, which otherwise showed very few changes. Protein carbonyl levels, a measure of oxidative stress, were increased in all depots. Thus, adipose tissues of markedly obese insulin resistant individuals uniformly show decreased AMPK activity and increased oxidative stress compared with insulin sensitive patients. However, most changes in gene expression appear to be depot-specific. PMID:22323564

  4. Plasma phospholipid transfer protein activity is independently determined by obesity and insulin resistance in non-diabetic subjects

    NARCIS (Netherlands)

    de Vries, Rindert; Kappelle, Paul J.W.H.; Dallinga-Thie, Geesje M.; Dullaart, Robin P. F.

    2011-01-01

    Background: Phospholipid transfer protein (PLTP) is an emerging cardio-metabolic risk factor which is intricately involved in lipoprotein metabolism. Elevated plasma PLTP activity levels are reported in obesity and diabetes mellitus, but the relative contributions of obesity and insulin resistance t

  5. Differential pathway coupling efficiency of the activated insulin receptor drives signaling selectivity by xmeta, an allosteric partial agonist antibody

    Science.gov (United States)

    XMetA, an anti-insulin receptor (IR) monoclonal antibody, is an allosteric partial agonist of the IR. We have previously reported that XMetA activates the “metabolic-biased” Akt kinase signaling pathway while having little or no effect on the “mitogenic” MAPK signaling pathwayof ERK 1/2. To inves...

  6. Intravenous tissue plasminogen activator in patients with stroke increases the bioavailability of insulin-like growth factor-1

    NARCIS (Netherlands)

    Wilczak, Nadine; Elting, Jan Willem; Chesik, Daniel; Kema, Ido P.; De Keyser, Jacques

    2006-01-01

    Background and Purpose-Insulin-like growth factor (IGF)-1 has potent neuroprotective properties. We investigated the effects of intravenous administration of tissue plasminogen activator (tPA) on serum levels of IGF-1 and IGF-binding protein (IGFBP)-3 in patients with acute ischemic stroke. Methods-

  7. Unacylated ghrelin rapidly modulates lipogenic and insulin signaling pathway gene expression in metabolically active tissues of GHSR deleted mice

    NARCIS (Netherlands)

    P.J.D. Delhanty (Patric); Y. Sun (Yuxiang); J.A. Visser (Jenny); A. Kerkwijk (Anke); M. Huisman (Martijn); W.F.J. van IJcken (Wilfred); S.M.A. Swagemakers (Sigrid)

    2010-01-01

    textabstractBackground: There is increasing evidence that unacylated ghrelin (UAG) improves insulin sensitivity and glucose homeostasis; however, the mechanism for this activity is not fully understood since a UAG receptor has not been discovered. Methodology/Principal Findings: To assess potential

  8. Plasma phospholipid transfer protein activity is independently determined by obesity and insulin resistance in non-diabetic subjects

    NARCIS (Netherlands)

    de Vries, Rindert; Kappelle, Paul J.W.H.; Dallinga-Thie, Geesje M.; Dullaart, Robin P. F.

    2011-01-01

    Background: Phospholipid transfer protein (PLTP) is an emerging cardio-metabolic risk factor which is intricately involved in lipoprotein metabolism. Elevated plasma PLTP activity levels are reported in obesity and diabetes mellitus, but the relative contributions of obesity and insulin resistance t

  9. Plasma phospholipid transfer protein activity is independently determined by obesity and insulin resistance in non-diabetic subjects

    NARCIS (Netherlands)

    de Vries, Rindert; Kappelle, Paul J.W.H.; Dallinga-Thie, Geesje M.; Dullaart, Robin P. F.

    Background: Phospholipid transfer protein (PLTP) is an emerging cardio-metabolic risk factor which is intricately involved in lipoprotein metabolism. Elevated plasma PLTP activity levels are reported in obesity and diabetes mellitus, but the relative contributions of obesity and insulin resistance

  10. Lifelong Physical Activity Prevents Aging-Associated Insulin Resistance in Human Skeletal Muscle Myotubes via Increased Glucose Transporter Expression

    DEFF Research Database (Denmark)

    Bunprajun, Tipwadee; Henriksen, Tora Ida; Scheele, Camilla

    2013-01-01

    , and significantly higher GLUT4 protein. It is likely that physical activity induces a number of stable adaptations, including increased GLUT4 expression that are retained in cells ex vivo and protect, or delay the onset of middle-aged-associated insulin resistance. Additionally, a sedentary lifestyle has an impact...

  11. Suppression of Adaptive Immune Cell Activation Does Not Alter Innate Immune Adipose Inflammation or Insulin Resistance in Obesity.

    Directory of Open Access Journals (Sweden)

    Manikandan Subramanian

    Full Text Available Obesity-induced inflammation in visceral adipose tissue (VAT is a major contributor to insulin resistance and type 2 diabetes. Whereas innate immune cells, notably macrophages, contribute to visceral adipose tissue (VAT inflammation and insulin resistance, the role of adaptive immunity is less well defined. To address this critical gap, we used a model in which endogenous activation of T cells was suppressed in obese mice by blocking MyD88-mediated maturation of CD11c+ antigen-presenting cells. VAT CD11c+ cells from Cd11cCre+Myd88fl/fl vs. control Myd88fl/fl mice were defective in activating T cells in vitro, and VAT T and B cell activation was markedly reduced in Cd11cCre+Myd88fl/fl obese mice. However, neither macrophage-mediated VAT inflammation nor systemic inflammation were altered in Cd11cCre+Myd88fl/fl mice, thereby enabling a focused analysis on adaptive immunity. Unexpectedly, fasting blood glucose, plasma insulin, and the glucose response to glucose and insulin were completely unaltered in Cd11cCre+Myd88fl/fl vs. control obese mice. Thus, CD11c+ cells activate VAT T and B cells in obese mice, but suppression of this process does not have a discernible effect on macrophage-mediated VAT inflammation or systemic glucose homeostasis.

  12. Mg2+-dependent ATPase activity in cardiac myofibrils from the insulin-resistant JCR:LA-cp rat.

    Science.gov (United States)

    Misra, T; Russell, J C; Clark, T A; Pierce, G N

    2001-01-01

    There is a great deal of information presently available documenting a cardiomyopathic condition in insulin-deficient models of diabetes. Less information is available documenting a similar status in non insulin-dependent models of diabetes. We have studied the functional integrity of the myofibrils isolated from hearts of JCR:LA rats. The JCR:LA rat is hyperinsulinemic, hyperlipidemic, glucose intolerant and obese. As such, it carries many of the characteristics found in humans with non insulin-dependent diabetes mellitus. These animals also have many indications of heart disease. However, it is not clear if the hearts suffer from vascular complications or are cardiomyopathic in nature. We examined Mg2+-dependent myofibrillar ATPase in hearts of JCR:LA-cp/cp rats and their corresponding control animals (+/?) and found no significant differences (P> 0.05). This is in striking contrast to the depression in this activity exhibited by cardiac myofibrils isolated from insulin-deficient models of diabetes. Our data demonstrate that myofibrillar functional integrity is normal in JCR:LA-cp rats and suggest that these hearts are not in a cardiomyopathic state. Insulin status may be critical in generating a cardiomyopathic condition in diabetes.

  13. Plasminogen Activator Inhibitor -1 (PAI-1) Predicts Negative Alterations in Whole Body Insulin Sensitivity in Chronic HIV Infection.

    Science.gov (United States)

    Wirunsawanya, Kamonkiat; Belyea, Loni; Shikuma, Cecilia; Watanabe, Richard; Kohorn, Lindsay; Shiramizu, Bruce; Mitchell, Brooks; Souza, Scott A; Keating, Sheila; Norris, Philip J; Ndhlovu, Lishomwa; Chow, Dominic

    2017-03-21

    Plasminogen activator inhibitor type 1 (PAI-1), a key negative regulator of fibrinolysis, has been investigated to be a potential predictor of the development of insulin resistance and diabetes mellitus. Because chronically stable HIV-infected individuals frequently develop abnormal glucose metabolism including insulin resistance and diabetes mellitus, we postulated PAI-1 could be one of multifactorial pathogenic roles in the development of insulin resistance among chronic HIV-infected individuals. From our longitudinal cohort study, we selectively recruited chronically stable HIV-infected individuals without diagnosis of diabetes mellitus at baseline (N = 62) to analyze the correlation of baseline inflammatory cytokines including PAI-1 and whole body insulin sensitivity with two-year follow-up, as measured by Matsuda Index. We found a negative correlation between baseline PAI-1 and Matsuda Index (r = -.435 , p = .001) and a negative correlation with PAI-1 at baseline and Matsuda Index at two years (r = -.377 , p = .005). In a linear regression model that included age, total body fat mass percentage, serum amyloid A and family history of diabetes mellitus, PAI-1 still remained significantly associated with Matsuda Index at two-year follow-up (β = -.397, p = .002). Our longitudinal study suggests PAI-1 is an independent predictor of insulin resistance among chronic HIV-infected individuals.

  14. Allosteric activation of protein phosphatase 2C by D-chiro-inositol-galactosamine, a putative mediator mimetic of insulin action.

    Science.gov (United States)

    Brautigan, D L; Brown, M; Grindrod, S; Chinigo, G; Kruszewski, A; Lukasik, S M; Bushweller, J H; Horal, M; Keller, S; Tamura, S; Heimark, D B; Price, J; Larner, A N; Larner, J

    2005-08-23

    Insulin-stimulated glucose disposal in skeletal muscle proceeds predominantly through a nonoxidative pathway with glycogen synthase as a rate-limiting enzyme, yet the mechanisms for insulin activation of glycogen synthase are not understood despite years of investigation. Isolation of putative insulin second messengers from beef liver yielded a pseudo-disaccharide consisting of pinitol (3-O-methyl-d-chiro-inositol) beta-1,4 linked to galactosamine chelated with Mn(2+) (called INS2). Here we show that chemically synthesized INS2 has biological activity that significantly enhances insulin reduction of hyperglycemia in streptozotocin diabetic rats. We used computer modeling to dock INS2 onto the known three-dimensional crystal structure of protein phosphatase 2C (PP2C). Modeling and FlexX/CScore energy minimization predicted a unique favorable site on PP2C for INS2 in a surface cleft adjacent to the catalytic center. Binding of INS2 is predicted to involve formation of multiple H-bonds, including one with residue Asp163. Wild-type PP2C activity assayed with a phosphopeptide substrate was potently stimulated in a dose-dependent manner by INS2. In contrast, the D163A mutant of PP2C was not activated by INS2. The D163A mutant and wild-type PP2C in the absence of INS2 had the same Mn(2+)-dependent phosphatase activity with p-nitrophenyl phosphate as a substrate, showing that this mutation did not disrupt the catalytic site. We propose that INS2 allosterically activates PP2C, fulfilling the role of a putative mediator mimetic of insulin signaling to promote protein dephosphorylation and metabolic responses.

  15. Data in support of fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice

    Directory of Open Access Journals (Sweden)

    Du-Qiang Luo

    2015-09-01

    Full Text Available This data article contains data related to the research article entitled “Fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice” in the Toxicology and Applied Pharmacology [1]. Fumosorinone (FU is a new inhibitor of protein phosphatase 1B inhibitor, which was isolated from insect pathogenic fungi Isaria fumosorosea. FU was found to inhibit PTP1B activity in our previous study [2]. PTP1B is the physiological antagonist of the insulin signalling pathway. Inhibition of PTP 1B may increase insulin sensitivity [3]. PTP1B has been considered promising as an insulin-sensitive drug target for the prevention and the treatment of insulin-based diseases [4]. We determined the effect of FU on the glucose consumption of IR HepG2 cells. FU caused significant enhancement in glucose consumption by insulin-resistant HepG2 cells compared with control cells.

  16. Data in support of fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice.

    Science.gov (United States)

    Luo, Du-Qiang; Liu, Zhi-Qin; Liu, Ting; Chen, Chuan; Li, Ming-Yan; Wang, Zi-Yu; Chen, Ruo-Song; Wei, Gui-Xiang; Wang, Xiao-Yi

    2015-09-01

    This data article contains data related to the research article entitled "Fumosorinone, a novel PTP1B inhibitor, activates insulin signaling in insulin-resistance HepG2 cells and shows anti-diabetic effect in diabetic KKAy mice" in the Toxicology and Applied Pharmacology [1]. Fumosorinone (FU) is a new inhibitor of protein phosphatase 1B inhibitor, which was isolated from insect pathogenic fungi Isaria fumosorosea. FU was found to inhibit PTP1B activity in our previous study [2]. PTP1B is the physiological antagonist of the insulin signalling pathway. Inhibition of PTP 1B may increase insulin sensitivity [3]. PTP1B has been considered promising as an insulin-sensitive drug target for the prevention and the treatment of insulin-based diseases [4]. We determined the effect of FU on the glucose consumption of IR HepG2 cells. FU caused significant enhancement in glucose consumption by insulin-resistant HepG2 cells compared with control cells.

  17. Exposure to static magnetic fields increases insulin secretion in rat INS-1 cells by activating the transcription of the insulin gene and up-regulating the expression of vesicle-secreted proteins.

    Science.gov (United States)

    Mao, Libin; Wang, Huiqin; Ma, Fenghui; Guo, Zhixia; He, Hongpeng; Zhou, Hao; Wang, Nan

    2017-08-01

    To evaluate the effect of static magnetic fields (SMFs) on insulin secretion and explore the mechanisms underlying exposure to SMF-induced insulin secretion in rat insulinoma INS-1 cells. INS-1 cells were exposed to a 400 mT SMF for 72 h, and the proliferation of INS-1 cells was detected by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The secretion of insulin was measured with an enzyme linked immunosorbent assays (ELISA), the expression of genes was detected by real-time PCR, and the expression of proteins was measured by Western blotting. Exposure to an SMF increased the expression and secretion of insulin by INS-1 cells but did not affect cell proliferation. Moreover, SMF exposure up-regulated the expression of several pancreas-specific transcriptional factors. Specifically, the activity of the rat insulin promoter was enhanced in INS-1 cells exposed to an SMF, and the expression levels of synaptosomal-associated protein 25 (SNAP-25) and syntaxin-1A were up-regulated after exposure to an SMF. SMF exposure can promote insulin secretion in rat INS-1 cells by activating the transcription of the insulin gene and up-regulating the expression of vesicle-secreted proteins.

  18. Activation of IGF-1 and insulin signaling pathways ameliorate mitochondrial function and energy metabolism in Huntington's Disease human lymphoblasts.

    Science.gov (United States)

    Naia, Luana; Ferreira, I Luísa; Cunha-Oliveira, Teresa; Duarte, Ana I; Ribeiro, Márcio; Rosenstock, Tatiana R; Laço, Mário N; Ribeiro, Maria J; Oliveira, Catarina R; Saudou, Frédéric; Humbert, Sandrine; Rego, A Cristina

    2015-02-01

    Huntington's disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine repeat expansion in the huntingtin protein. Mitochondrial dysfunction associated with energy failure plays an important role in this untreated pathology. In the present work, we used lymphoblasts obtained from HD patients or unaffected parentally related individuals to study the protective role of insulin-like growth factor 1 (IGF-1) versus insulin (at low nM) on signaling and metabolic and mitochondrial functions. Deregulation of intracellular signaling pathways linked to activation of insulin and IGF-1 receptors (IR,IGF-1R), Akt, and ERK was largely restored by IGF-1 and, at a less extent, by insulin in HD human lymphoblasts. Importantly, both neurotrophic factors stimulated huntingtin phosphorylation at Ser421 in HD cells. IGF-1 and insulin also rescued energy levels in HD peripheral cells, as evaluated by increased ATP and phosphocreatine, and decreased lactate levels. Moreover, IGF-1 effectively ameliorated O2 consumption and mitochondrial membrane potential (Δψm) in HD lymphoblasts, which occurred concomitantly with increased levels of cytochrome c. Indeed, constitutive phosphorylation of huntingtin was able to restore the Δψm in lymphoblasts expressing an abnormal expansion of polyglutamines. HD lymphoblasts further exhibited increased intracellular Ca(2+) levels before and after exposure to hydrogen peroxide (H2O2), and decreased mitochondrial Ca(2+) accumulation, being the later recovered by IGF-1 and insulin in HD lymphoblasts pre-exposed to H2O2. In summary, the data support an important role for IR/IGF-1R mediated activation of signaling pathways and improved mitochondrial and metabolic function in HD human lymphoblasts.

  19. Selective Activation of Estrogen Receptor α Activation Function-1 Is Sufficient to Prevent Obesity, Steatosis, and Insulin Resistance in Mouse.

    Science.gov (United States)

    Guillaume, Maeva; Handgraaf, Sandra; Fabre, Aurélie; Raymond-Letron, Isabelle; Riant, Elodie; Montagner, Alexandra; Vinel, Alexia; Buscato, Melissa; Smirnova, Natalia; Fontaine, Coralie; Guillou, Hervé; Arnal, Jean-François; Gourdy, Pierre

    2017-06-01

    Estrogen receptor α (ERα) regulates gene transcription through two activation functions (ERα-AF1 and ERα-AF2). We recently found that the protection conferred by 17β-estradiol against obesity and insulin resistance requires ERα-AF2 but not ERα-AF1. However, the interplay between the two ERα-AFs is poorly understood in vivo and the metabolic influence of a specific ERα-AF1 action remains to be explored. To this end, wild-type, ERα-deficient, or ERα-AF1-deficient ovariectomized female mice were fed a high-fat diet and concomitantly administered with vehicle or tamoxifen, a selective ER modulator that acts as a ERα-AF1 agonist/ERα-AF2 antagonist. In ovariectomized wild-type mice, tamoxifen significantly reduced food intake and totally prevented adiposity, insulin resistance, and steatosis. These effects were abolished in ERα-deficient and ERα-AF1-deficient mice, revealing the specific role of ERα-AF1 activation. Finally, hepatic gene expression changes elicited by tamoxifen in wild-type mice were abrogated in ERα-AF1-deficient mice. The combination of pharmacologic and transgenic approaches thus indicates that selective ERα-AF1 activation by tamoxifen is sufficient to elicit metabolic protection, contrasting with the specific requirement of ERα-AF2 in the metabolic actions of 17β-estradiol. This redundancy in the ability of the two ERα-AFs to separately mediate metabolic prevention strikingly contrasts with the contribution of both ERα-AFs in breast cancer proliferation, shedding new light on the therapeutic potential of selective ER modulation. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  20. In vivo activity of 11beta-hydroxysteroid dehydrogenase type 1 and free fatty acid-induced insulin resistance.

    Science.gov (United States)

    Mai, K; Kullmann, V; Bobbert, T; Maser-Gluth, C; Möhlig, M; Bähr, V; Pfeiffer, A F H; Spranger, J; Diederich, S

    2005-10-01

    Free fatty acids (FFAs) induce hepatic insulin resistance and enhance hepatic gluconeogenesis. Glucocorticoids (GCs) also stimulate hepatic gluconeogenesis. The aim of this study was to investigate whether the FFA-induced hepatic insulin resistance is mediated by increased activity of hepatic 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), accompanied by elevated hepatic cortisol levels. Following a 10-h overnight fast, six healthy male volunteers were investigated. A euglycaemic hyperinsulinaemic clamp was performed during lipid or saline infusion. To assess hepatic 11beta-HSD1 activity, plasma cortisol levels were measured after oral administration of cortisone acetate during lipid or saline infusion. In addition, 11beta-HSD activities were determined in vivo by calculating the urinary ratios of GC metabolites. Lipid infusion increased FFAs (5.41 +/- 1.00 vs. 0.48 +/- 0.20 mmol/l; P < 0.005) and significantly increased insulin resistance [glucose infusion rate (GIR) 6.02 +/- 2.60 vs. 4.08 +/- 2.15 mg/kg/min; P < 0.005]. After lipid and saline infusions no changes in 11beta-HSD1 activity were found, neither by changes in cortisone acetate to cortisol conversion nor by differences in urinary free cortisol (UFF) or cortisone (UFE), 5beta-tetrahydrocortisol (THF), 5alpha-THF, cortisone (THE), UFF/UFE and (5alpha-THF + THF)/THE ratios. We found no change in hepatic and whole-body 11beta-HSD1 activity during acute FFA-induced insulin resistance. Further studies are necessary to clarify whether 11beta-HSD1 in muscle and adipose tissue is influenced by FFAs and whether 11beta-HSD1 is involved in other conditions of insulin resistance.

  1. Enhanced insulin sensitivity mediated by adipose tissue browning perturbs islet morphology and hormone secretion in response to autonomic nervous activation in female mice.

    Science.gov (United States)

    Omar, Bilal A; Kvist-Reimer, Martina; Enerbäck, Sven; Ahrén, Bo

    2016-01-01

    Insulin resistance results in a compensatory increase in insulin secretion to maintain normoglycemia. Conversely, high insulin sensitivity results in reduced insulin secretion to prevent hypoglycemia. The mechanisms for this inverse adaptation are not well understood. We utilized highly insulin-sensitive mice, due to adipocyte-specific overexpression of the FOXC2 transcription factor, to study mechanisms of the reversed islet adaptation to increased insulin sensitivity. We found that Foxc2TG mice responded to mild hyperglycemia with insulin secretion significantly lower than that of wild-type mice; however, when severe hyperglycemia was induced, Foxc2TG mice demonstrated insulin secretion equal to or greater than that of wild-type mice. In response to autonomic nervous activation by 2-deoxyglucose, the acute suppression of insulin seen in wild-type mice was absent in Foxc2TG mice, suggesting impaired sympathetic signaling to the islet. Basal glucagon was increased in Foxc2TG mice, but they displayed severely impaired glucagon responses to cholinergic and autonomic nervous stimuli. These data suggest that the autonomic nerves contribute to the islet adaptation to high insulin sensitivity, which is compatible with a neuro-adipo regulation of islet function being instrumental for maintaining glucose regulation.

  2. Reciprocal regulation of insulin and plasma 5'-AMP in glucose homeostasis in mice.

    Science.gov (United States)

    Xia, Lin; Wang, Zhongqiu; Zhang, Ying; Yang, Xiao; Zhan, Yibei; Cheng, Rui; Wang, Shiming; Zhang, Jianfa

    2015-03-01

    A previous investigation has demonstrated that plasma 5'-AMP (pAMP) exacerbates and causes hyperglycemia in diabetic mice. However, the crosstalk between pAMP and insulin signaling to regulate glucose homeostasis has not been investigated in depth. In this study, we showed that the blood glucose level was more dependent on the ratio of insulin to pAMP than on the absolute level of these two factors. Administration of 5'-AMP significantly attenuated the insulin-stimulated insulin receptor (IR) autophosphorylation in the liver and muscle tissues, resulting in the inhibition of downstream AKT phosphorylation. A docking analysis indicated that adenosine was a potential inhibitor of IR tyrosine kinase. Moreover, the 5'-AMP treatment elevated the ATP level in the pancreas and in the isolated islets, stimulating insulin secretion and increasing the plasma level of insulin. The insulin administration decreased the 5'-AMP-induced hyper-adenosine level by the up-regulation of adenosine kinase activities. Our results indicate that blood glucose homeostasis is reciprocally regulated by pAMP and insulin.

  3. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons

    Science.gov (United States)

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We sho...

  4. Improved insulin sensitivity and islet function after PPARdelta activation in diabetic db/db mice.

    Science.gov (United States)

    Winzell, Maria Sörhede; Wulff, Erik Max; Olsen, Grith Skytte; Sauerberg, Per; Gotfredsen, Carsten F; Ahrén, Bo

    2010-01-25

    The peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily. Several reports have shown that PPARdelta is involved in lipid metabolism, increasing fat oxidation and depleting lipid accumulation. Whether PPARdelta is involved in the regulation of glucose metabolism is not completely understood. In this study, we examined effects of long-term PPARdelta activation on glycemic control, islet function and insulin sensitivity in diabetic db/db mice. Male db/db mice were administered orally once daily with a selective and partial PPARdelta agonist (NNC 61-5920, 30 mg/kg) for eight weeks; control mice received vehicle. Fasting and non-fasting plasma glucose were reduced, reflected in reduced hemoglobinA(1c) (3.6+/-1.6% vs. 5.4+/-1.8 in db/db controls, Pdiabetic db/db mice. This suggests that activation of PPARdelta improves glucose metabolism and may therefore potentially be target for treatment of type 2 diabetes.

  5. Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 Deficiency Reduces Insulin Sensitivity in High-Fat Diet-Fed Mice

    NARCIS (Netherlands)

    de Boer, Jan Freark; Dikkers, Arne; Jurdzinski, Angelika; von Felden, Johann; Gaestel, Matthias; Bavendiek, Udo; Tietge, Uwe J. F.

    2014-01-01

    Adipose tissue inflammation is considered an important contributor to insulin resistance. Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a major downstream target of p38 MAPK and enhances inflammatory processes. In line with the role of MK2 as contributor to inflammation,

  6. Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 Deficiency Reduces Insulin Sensitivity in High-Fat Diet-Fed Mice

    NARCIS (Netherlands)

    de Boer, Jan Freark; Dikkers, Arne; Jurdzinski, Angelika; von Felden, Johann; Gaestel, Matthias; Bavendiek, Udo; Tietge, Uwe J. F.

    2014-01-01

    Adipose tissue inflammation is considered an important contributor to insulin resistance. Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a major downstream target of p38 MAPK and enhances inflammatory processes. In line with the role of MK2 as contributor to inflammation, MK2(-

  7. Ethanolic extract of Allium cepa stimulates glucose transporter typ 4-mediated glucose uptake by the activation of insulin signaling.

    Science.gov (United States)

    Gautam, Sudeep; Pal, Savita; Maurya, Rakesh; Srivastava, Arvind K

    2015-02-01

    The present work was undertaken to investigate the effects and the molecular mechanism of the standardized ethanolic extract of Allium cepa (onion) on the glucose transport for controlling diabetes mellitus. A. cepa stimulates glucose uptake by the rat skeletal muscle cells (L6 myotubes) in both time- and dose-dependent manners. This effect was shown to be mediated by the increased translocation of glucose transporter typ 4 protein from the cytoplasm to the plasma membrane as well as the synthesis of glucose transporter typ 4 protein. The effect of A. cepa extract on glucose transport was stymied by wortmannin, genistein, and AI½. In vitro phosphorylation analysis revealed that, like insulin, A. cepa extract also enhances the tyrosine phosphorylation of the insulin receptor-β, insulin receptor substrate-1, and the serine phosphorylation of Akt under both basal and insulin-stimulated conditions without affecting the total amount of these proteins. Furthermore, it is also shown that the activation of Akt is indispensable for the A. cepa-induced glucose uptake in L6 myotubes. Taken together, these findings provide ample evidence that the ethanolic extract of A. cepa stimulates glucose transporter typ 4 translocation-mediated glucose uptake by the activation of the phosphatidylinositol-4,5-bisphosphate 3-kinase/Akt dependent pathway.

  8. Fibronectin and laminin promote differentiation of human mesenchymal stem cells into insulin producing cells through activating Akt and ERK

    Directory of Open Access Journals (Sweden)

    Chiou Shih-Hwa

    2010-07-01

    Full Text Available Abstract Background Islet transplantation provides a promising cure for Type 1 diabetes; however it is limited by a shortage of pancreas donors. Bone marrow-derived multipotent mesenchymal stem cells (MSCs offer renewable cells for generating insulin-producing cells (IPCs. Methods We used a four-stage differentiation protocol, containing neuronal differentiation and IPC-conversion stages, and combined with pellet suspension culture to induce IPC differentiation. Results Here, we report adding extracellular matrix proteins (ECM such as fibronectin (FN or laminin (LAM enhances pancreatic differentiation with increases in insulin and Glut2 gene expressions, proinsulin and insulin protein levels, and insulin release in response to elevated glucose concentration. Adding FN or LAM induced activation of Akt and ERK. Blocking Akt or ERK by adding LY294002 (PI3K specific inhibitor, PD98059 (MEK specific inhibitor or knocking down Akt or ERK failed to abrogate FN or LAM-induced enhancement of IPC differentiation. Only blocking both of Akt and ERK or knocking down Akt and ERK inhibited the enhancement of IPC differentiation by adding ECM. Conclusions These data prove IPC differentiation by MSCs can be modulated by adding ECM, and these stimulatory effects were mediated through activation of Akt and ERK pathways.

  9. Functional abolition of carotid body activity restores insulin action and glucose homeostasis in rats: key roles for visceral adipose tissue and the liver.

    Science.gov (United States)

    Sacramento, Joana F; Ribeiro, Maria J; Rodrigues, Tiago; Olea, Elena; Melo, Bernardete F; Guarino, Maria P; Fonseca-Pinto, Rui; Ferreira, Cristiana R; Coelho, Joana; Obeso, Ana; Seiça, Raquel; Matafome, Paulo; Conde, Sílvia V

    2017-01-01

    We recently described that carotid body (CB) over-activation is involved in the aetiology of insulin resistance and arterial hypertension in animal models of the metabolic syndrome. Additionally, we have demonstrated that CB activity is increased in animal models of insulin resistance, and that carotid sinus nerve (CSN) resection prevents the development of insulin resistance and arterial hypertension induced by high-energy diets. Here, we tested whether the functional abolition of CB by CSN transection would reverse pre-established insulin resistance, dyslipidaemia, obesity, autonomic dysfunction and hypertension in animal models of the metabolic syndrome. The effect of CSN resection on insulin signalling pathways and tissue-specific glucose uptake was evaluated in skeletal muscle, adipose tissue and liver. Experiments were performed in male Wistar rats submitted to two high-energy diets: a high-fat diet, representing a model of insulin resistance, hypertension and obesity, and a high-sucrose diet, representing a lean model of insulin resistance and hypertension. Half of each group was submitted to chronic bilateral resection of the CSN. Age-matched control rats were also used. CSN resection normalised systemic sympathetic nervous system activity and reversed weight gain induced by high-energy diets. It also normalised plasma glucose and insulin levels, insulin sensitivity lipid profile, arterial pressure and endothelial function by improving glucose uptake by the liver and perienteric adipose tissue. We concluded that functional abolition of CB activity restores insulin sensitivity and glucose homeostasis by positively affecting insulin signalling pathways in visceral adipose tissue and liver.

  10. Anti-hyperlipidemic and insulin sensitizing activities of fenofibrate reduces aortic lipid deposition in hyperlipidemic Golden Syrian hamster.

    Science.gov (United States)

    Srivastava, Rai Ajit K; He, Shirley

    2010-12-01

    Cholesterol ester transfer protein (CETP) and apolipoprotein (apo) E are important in peroxisome proliferation activated receptor-α (PPAR-α)-mediated regulation of lipoprotein metabolism. Therefore, popularly used apolipoprotein E knockout mice are not suitable to evaluate PPAR-α agonists. In this study, we aimed to: a) evaluate hamster as a model for insulin resistance, hyperlipidemia and atherosclerosis; and b) investigate the effect of a PPAR-α activator, fenofibrate, in this model. A high fat high cholesterol (HFHC) diet increased serum cholesterol and triglycerides, but inclusion of fenofibrate in the diet decreased cholesterol and proatherogenic lipoproteins, VLDL and LDL, in a time-dependent manner. Concomitantly, serum levels of triglycerides also decreased. These reductions were attributed, in part, to the down-regulation of lipogenic genes and upregulation of lipoprotein lipase. The HFHC diet caused body weight gain and mild insulin resistance, both of which were prevented following the treatments with fenofibrate. Insulin resistance was further investigated in high fructose-fed hamsters. Fenofibrate prevented both hyperinsulinemia and hypertriglyceridemia. The insulin sensitizing activity of fenofibrate appeared to occur via reductions in protein tyrosine phophatase-1B. To determine whether lowering of lipids by fenofibrate treatment contributed to the reduced risks of developing atherosclerosis in hyperlipidemic hamsters, we measured lipid deposition in the aorta. Our results showed that fenofibrate treatment reduced aortic lipid deposition by 70%. These findings suggest that hamster may be an adequate animal model to evaluate the efficacy of lipid lowering, insulin sensitizing and antiatherosclerotic agents. We also show that fenofibrate is an effective antiatherosclerotic agent in hyperlipidemic hamster model.

  11. Physical activity-induced improvements in markers of insulin resistance in overweight and obese children and adolescents.

    Science.gov (United States)

    Tompkins, Connie L; Moran, Kelsey; Preedom, Stephanie; Brock, David W

    2011-05-01

    Childhood obesity is a significant, worldwide, public health problem. Coinciding with the increasing prevalence of obesity in youth, Type 2 diabetes has emerged as a critical health condition in this population. In the U.S. alone, approximately 215,000 U.S. youth under the age of 20 were diagnosed with diabetes, with the majority of 10-19 years old diagnosed with Type 2 diabetes. Additionally, the exact number of youth that may have Type 2 diabetes yet remain undiagnosed is unknown. Increasing physical activity to encourage weight loss among youth may reduce the incidence of Type 2 diabetes in youth; however, several recent studies reported positive associations between physical activity and components of Type 2 diabetes without weight loss in youth. These findings support previous studies in adults which observed physical activity-induced improvements in insulin dynamics without changes in body fat. The purpose of this review was to identify studies which examined the effect of physical activity without dietary intervention on markers of insulin resistance in overweight and obese youth. These studies provide strong evidence that physical activity alone, without dietary intervention, can have a positive, significant impact on insulin resistance risk and potentially prevent the development of type 2 diabetes in overweight and obese youth. The studies reviewed provide support for future interventions to shift the focus from reducing obesity to increasing physical activity for the prevention of type 2 diabetes in obese youth.

  12. Diet-induced obesity exacerbates metabolic and behavioral effects of polycystic ovary syndrome in a rodent model.

    Science.gov (United States)

    Ressler, Ilana B; Grayson, Bernadette E; Ulrich-Lai, Yvonne M; Seeley, Randy J

    2015-06-15

    Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting women of reproductive age. Although a comorbidity of PCOS is obesity, many are lean. We hypothesized that increased saturated fat consumption and obesity would exacerbate metabolic and stress indices in a rodent model of PCOS. Female rats were implanted with the nonaromatizable androgen dihydrotestosterone (DHT) or placebo pellets prior to puberty. Half of each group was maintained ad libitum on either a high-fat diet (HFD; 40% butter fat calories) or nutrient-matched low-fat diet (LFD). Irrespective of diet, DHT-treated animals gained more body weight, had irregular cycles, and were glucose intolerant compared with controls on both diets. HFD/DHT animals had the highest levels of fat mass and insulin resistance. DHT animals demonstrated increased anxiety-related behavior in the elevated plus maze by decreased distance traveled and time in the open arms. HFD consumption increased immobility during the forced-swim test. DHT treatment suppressed diurnal corticosterone measurements in both diet groups. In parallel, DHT treatment significantly dampened stress responsivity to a mild stressor. Brains of DHT animals showed attenuated c-Fos activation in the ventromedial hypothalamus and arcuate nucleus; irrespective of DHT-treatment, however, all HFD animals had elevated hypothalamic paraventricular nucleus c-Fos activation. Whereas hyperandrogenism drives overall body weight gain, glucose intolerance, anxiety behaviors, and stress responsivity, HFD consumption exacerbates the effect of androgens on adiposity, insulin resistance, and depressive behaviors.

  13. Hepatic oxidative stress promotes insulin-STAT-5 signaling and obesity by inactivating protein tyrosine phosphatase N2

    Science.gov (United States)

    Gurzov, Esteban N.; Tran, Melanie; Fernandez-Rojo, Manuel A; Merry, Troy L; Zhang, Xinmei; Xu, Yang; Fukushima, Atsushi; Waters, Michael J; Watt, Matthew J; Andrikopoulos, Sofianos; Neel, Benjamin G; Tiganis, Tony

    2015-01-01

    Hepatic insulin resistance is a key contributor to the pathogenesis of obesity and type 2 diabetes (T2D). Paradoxically the development of insulin resistance in the liver is not universal, but pathway-selective, such that insulin fails to suppress gluconeogenesis but promotes lipogenesis, contributing to the hyperglycemia, steatosis and hypertriglyceridemia that underpin the deteriorating glucose control and microvascular complications in T2D. The molecular basis for the pathway-specific insulin resistance remains unknown. Here we report that oxidative stress accompanying obesity inactivates protein-tyrosine phosphatases (PTPs) in the liver, which activates select signaling pathways that exacerbate disease progression. In obese mice, hepatic PTPN2 (TCPTP) inactivation promoted lipogenesis and steatosis and insulin-STAT-5 signaling. The enhanced STAT-5 signaling increased hepatic IGF-1 production, which suppressed central growth hormone release and exacerbated the development of obesity and T2D. Our studies define a mechanism for the development of selective insulin resistance with wide-ranging implications for diseases characterised by oxidative stress. PMID:24954415

  14. Insulin Test

    Science.gov (United States)

    ... especially as a result of taking non-human (animal or synthetic) insulin, these can interfere with insulin testing. In this case, a C-peptide may be performed as an alternative way to evaluate insulin production. Note also that ...

  15. Insulin Secretagogues

    Science.gov (United States)

    ... Nondiabetic Hypoglycemia Featured Resource Find an Endocrinologist Search Insulin Secretagogues March 2012 Download PDFs English Espanol Editors ... Julio Rosenstock, MD Additional Resources FDA What are insulin secretagogues? Insulin secretagogues (pronounced seh-KREET-ah-gogs) ...

  16. Radiation-Induced Esophagitis Exacerbated by Everolimus

    Directory of Open Access Journals (Sweden)

    Yuji Miura

    2013-06-01

    Full Text Available Background: Everolimus, a potent mammalian target of rapamycin (mTOR inhibitor, has shown anticancer activity against various types of cancer, including renal cell carcinoma (RCC; however, little information is available on the efficacy and safety of the combination of everolimus and radiotherapy. We report a case of radiation-induced esophagitis that might have been exacerbated by the sequential administration of everolimus. Case Presentation: A 63-year-old Japanese man with RCC complained of back pain, and magnetic resonance imaging revealed vertebral metastases. He received radiotherapy (30 Gy/10 fractions to the T6-10 vertebrae. Everolimus was administered immediately after the completion of radiotherapy. One week later, he complained of dysphagia, nausea and vomiting. An endoscopic examination of the esophagus showed erosive esophagitis in the middle to lower portions of his thoracic esophagus, corresponding to the irradiation field. Conclusion: Clinicians should be aware that everolimus might lead to the unexpected exacerbation of radiation toxicities.

  17. Insulin action and insulin resistance in vascular endothelium.

    Science.gov (United States)

    Muniyappa, Ranganath; Quon, Michael J

    2007-07-01

    Vasodilator actions of insulin are mediated by phosphatidylinositol 3-kinase dependent insulin signaling pathways in endothelium, which stimulate production of nitric oxide. Insulin-stimulated nitric oxide mediates capillary recruitment, vasodilation, increased blood flow, and subsequent augmentation of glucose disposal in skeletal muscle. Distinct mitogen-activated protein kinase dependent insulin signaling pathways regulate secretion of the vasoconstrictor endothelin-1 from endothelium. These vascular actions of insulin contribute to the coupling of metabolic and hemodynamic homeostasis that occurs under healthy conditions. Insulin resistance is characterized by pathway-specific impairment in phosphatidylinositol 3-kinase dependent signaling in both metabolic and vascular insulin target tissues. Here we discuss consequences of pathway-specific insulin resistance in endothelium and therapeutic interventions targeting this selective impairment. Shared causal factors such as glucotoxicity, lipotoxicity, and inflammation selectively impair phosphatidylinositol 3-kinase dependent insulin signaling pathways, creating reciprocal relationships between insulin resistance and endothelial dysfunction. Diet, exercise, cardiovascular drugs, and insulin sensitizers simultaneously modulate phosphatidylinositol 3-kinase and mitogen-activated protein kinase dependent pathways, improving metabolic and vascular actions of insulin. Pathway-specific impairment in insulin action contributes to reciprocal relationships between endothelial dysfunction and insulin resistance, fostering clustering of metabolic and cardiovascular diseases in insulin-resistant states. Therapeutic interventions that target this selective impairment often simultaneously improve both metabolic and vascular function.

  18. Hmgcr in the corpus allatum controls sexual dimorphism of locomotor activity and body size via the insulin pathway in Drosophila.

    Directory of Open Access Journals (Sweden)

    Yesser Hadj Belgacem

    Full Text Available The insulin signaling pathway has been implicated in several physiological and developmental processes. In mammals, it controls expression of 3-Hydroxy-3-Methylglutaryl CoA Reductase (HMGCR, a key enzyme in cholesterol biosynthesis. In insects, which can not synthesize cholesterol de novo, the HMGCR is implicated in the biosynthesis of juvenile hormone (JH. However, the link between the insulin pathway and JH has not been established. In Drosophila, mutations in the insulin receptor (InR decrease the rate of JH synthesis. It is also known that both the insulin pathway and JH play a role in the control of sexual dimorphism in locomotor activity. In studies here, to demonstrate that the insulin pathway and HMGCR are functionally linked in Drosophila, we first show that hmgcr mutation also disrupts the sexual dimorphism. Similarly to the InR, HMGCR is expressed in the corpus allatum (ca, which is the gland where JH biosynthesis occurs. Two p[hmgcr-GAL4] lines were therefore generated where RNAi was targeted specifically against the HMGCR or the InR in the ca. We found that RNAi-HMGCR blocked HMGCR expression, while the RNAi-InR blocked both InR and HMGCR expression. Each RNAi caused disruption of sexual dimorphism and produced dwarf flies at specific rearing temperatures. These results provide evidence: (i that HMGCR expression is controlled by the InR and (ii that InR and HMGCR specifically in the ca, are involved in the control of body size and sexual dimorphism of locomotor activity.

  19. PPARalpha activation and increased dietary lipid oppose thyroid hormone signaling and rescue impaired glucose-stimulated insulin secretion in hyperthyroidism.

    Science.gov (United States)

    Holness, Mark J; Greenwood, Gemma K; Smith, Nicholas D; Sugden, Mary C

    2008-12-01

    The aim of the study was to investigate the impact of hyperthyroidism on the characteristics of the islet insulin secretory response to glucose, particularly the consequences of competition between thyroid hormone and peroxisome proliferator-activated receptor (PPAR)alpha in the regulation of islet adaptations to starvation and dietary lipid-induced insulin resistance. Rats maintained on standard (low-fat/high-carbohydrate) diet or high-fat/low-carbohydrate diet were rendered hyperthyroid (HT) by triiodothyronine (T(3)) administration (1 mg.kg body wt(-1).day(-1) sc, 3 days). The PPARalpha agonist WY14643 (50 mg/kg body wt ip) was administered 24 h before sampling. Glucose-stimulated insulin secretion (GSIS) was assessed during hyperglycemic clamps or after acute glucose bolus injection in vivo and with step-up and step-down islet perifusions. Hyperthyroidism decreased the glucose responsiveness of GSIS, precluding sufficient enhancement of insulin secretion for the degree of insulin resistance, in rats fed either standard diet or high-fat diet. Hyperthyroidism partially opposed the starvation-induced increase in the glucose threshold for GSIS and decrease in glucose responsiveness. WY14643 administration restored glucose tolerance by enhancing GSIS in fed HT rats and relieved the impact of hyperthyroidism to partially oppose islet starvation adaptations. Competition between thyroid hormone receptor (TR) and PPARalpha influences the characteristics of GSIS, such that hyperthyroidism impairs GSIS while PPARalpha activation (and increased dietary lipid) opposes TR signaling and restores GSIS in the fed hyperthyroid state. Increased islet PPARalpha signaling and decreased TR signaling during starvation facilitates appropriate modification of islet function.

  20. Exacerbation of symptoms in agricultural pesticide applicators with asthma.

    Science.gov (United States)

    Henneberger, Paul K; Liang, Xiaoming; London, Stephanie J; Umbach, David M; Sandler, Dale P; Hoppin, Jane A

    2014-05-01

    Exacerbation is a critical event in asthma management. We investigated whether exacerbation of symptoms is associated with farming exposures among agricultural pesticide applicators with asthma. Participants were pesticide applicators with active asthma (wheezing and breathing problems in past 12 months) who completed enrollment questionnaires for the Agricultural Health Study (AHS). Exacerbation of asthma was defined as having visited a hospital emergency room or doctor for an episode of wheezing or whistling in the past 12 months. Exposures of interest were using 36 specific pesticides in the past 12 months and conducting various agricultural activities. Adjusted odds ratios (ORs) were estimated by logistic regression while controlling for potential confounders. The 926 AHS adult pesticide applicators with active asthma included 202 (22%) with exacerbation. Inverse associations with exacerbation were observed for two herbicides [glyphosate, odds ratio (OR) = 0.5, 95% confidence interval (CI) 0.3, 0.8, and paraquat, OR = 0.3, 95% CI 0.1, 0.9] and several agricultural activities (repairing engines, grinding metal, driving diesel tractors, and performing veterinary procedures). Only asthma cases with allergies (i.e., doctor-diagnosed hay fever or eczema, 46%) had positive exacerbation-pesticide associations, with OR = 2.1 (95% CI 1.1, 4.1) for the herbicide pendimethalin and OR = 10.2 (95% CI 1.9, 55) for the insecticide aldicarb. The inverse associations with two pesticides and specific farm activities are consistent with the possibility that asthma cases prone to exacerbation may avoid exposures that trigger symptoms. Although limited by small sample size and a cross-sectional design, our study suggests that use of specific pesticides may contribute to exacerbation of asthma among individuals with allergies.

  1. Glutamine:fructose-6-phosphate amidotransferase activity in cultured human skeletal muscle cells: relationship to glucose disposal rate in control and non-insulin-dependent diabetes mellitus subjects and regulation by glucose and insulin.

    OpenAIRE

    1996-01-01

    We examined the activity of the rate-limiting enzyme for hexosamine biosynthesis, glutamine:fructose-6-phosphate amidotransferase (GFA) in human skeletal muscle cultures (HSMC), from 17 nondiabetic control and 13 subjects with non-insulin-dependent diabetes. GFA activity was assayed from HSMC treated with low (5 mM) or high (20 mM) glucose and low (22 pM) or high (30 microM) concentrations of insulin. In control subjects GFA activity decreased with increasing glucose disposal rate (r = -0.68,...

  2. Insulin activates single amiloride-blockable Na channels in a distal nephron cell line (A6).

    Science.gov (United States)

    Marunaka, Y; Hagiwara, N; Tohda, H

    1992-09-01

    Using the patch-clamp technique, we studied the effect of insulin on an amiloride-blockable Na channel in the apical membrane of a distal nephron cell line (A6) cultured on permeable collagen films for 10-14 days. NPo (N, number of channels per patch membrane; Po, average value of open probability of individual channels in the patch) under baseline conditions was 0.88 +/- 0.12 (SE)(n = 17). After making cell-attached patches on the apical membrane which contained Na channels, insulin (1 mU/ml) was applied to the serosal bath. While maintaining the cell-attached patch, NPo significantly increased to 1.48 +/- 0.19 (n = 17; P less than 0.001) after 5-10 min of insulin application. The open probability of Na channels was 0.39 +/- 0.01 (n = 38) under baseline condition, and increased to 0.66 +/- 0.03 (n = 38, P less than 0.001) after addition of insulin. The baseline single-channel conductance was 4pS, and neither the single-channel conductance nor the current-voltage relationship was significantly changed by insulin. These results indicate that insulin increases Na absorption in the distal nephron by increasing the open probability of the amiloride-blockable Na channel.

  3. Exacerbations of asthma during pregnancy

    DEFF Research Database (Denmark)

    Ali, Z; Hansen, A V; Ulrik, C S

    2016-01-01

    Asthma is common among pregnant women, and the incidence of asthma exacerbations during pregnancy is high. This literature review provides an overview of the impact of exacerbations of asthma during pregnancy on pregnancy-related complications. The majority of published retrospective studies reveal...... that asthma exacerbations during pregnancy increase the risk of pre-eclampsia, gestational diabetes, placental abruption and placenta praevia. Furthermore, these women also have higher risk for breech presentation, haemorrhage, pulmonary embolism, caesarean delivery, maternal admission to the intensive care...... unit and longer postpartum hospital stay. Asthma has been associated with increased risk of intrauterine growth retardation, small-for-gestational age, low birth weight, infant hypoglycaemia and preterm birth, but more recent prospective studies have not revealed significant associations with regard...

  4. Ablation of AMP-activated protein kinase alpha1 and alpha2 from mouse pancreatic beta cells and RIP2.Cre neurons suppresses insulin release in vivo.

    Science.gov (United States)

    Sun, G; Tarasov, A I; McGinty, J; McDonald, A; da Silva Xavier, G; Gorman, T; Marley, A; French, P M; Parker, H; Gribble, F; Reimann, F; Prendiville, O; Carzaniga, R; Viollet, B; Leclerc, I; Rutter, G A

    2010-05-01

    AMP-activated protein kinase (AMPK) is an evolutionarily conserved enzyme and a target of glucose-lowering agents, including metformin. However, the precise role or roles of the enzyme in controlling insulin secretion remain uncertain. The catalytic alpha1 and alpha2 subunits of AMPK were ablated selectively in mouse pancreatic beta cells and hypothalamic neurons by breeding Ampkalpha1 [also known as Prkaa1]-knockout mice, bearing floxed Ampkalpha2 [also known as Prkaa2] alleles (Ampkalpha1 ( -/- ),alpha2( fl/fl ),), with mice expressing Cre recombinase under the rat insulin promoter (RIP2). RIP2 was used to express constitutively activated AMPK selectively in beta cells in transgenic mice. Food intake, body weight and urinary catecholamines were measured using metabolic cages. Glucose and insulin tolerance were determined after intraperitoneal injection. Beta cell mass and morphology were analysed by optical projection tomography and confocal immunofluorescence microscopy, respectively. Granule docking, insulin secretion, membrane potential and intracellular free Ca(2+) were measured with standard techniques. Trigenic Ampkalpha1 ( -/- ),alpha2( fl/fl ) expressing Cre recombinase and lacking both AMPKalpha subunits in the beta cell, displayed normal body weight and increased insulin sensitivity, but were profoundly insulin-deficient. Secreted catecholamine levels were unchanged. Total beta cell mass was unaltered, while mean islet and beta cell volume were reduced. AMPK-deficient beta cells displayed normal glucose-induced changes in membrane potential and intracellular free Ca(2+), while granule docking and insulin secretion were enhanced. Conversely, betaAMPK transgenic mice were glucose-intolerant and displayed defective insulin secretion. Inhibition of AMPK activity within the beta cell is necessary, but not sufficient for stimulation of insulin secretion by glucose to occur. AMPK activation in extrapancreatic RIP2.Cre-expressing cells might also influence

  5. The inability of phosphatidylinositol 3-kinase activation to stimulate GLUT4 translocation indicates additional signaling pathways are required for insulin-stimulated glucose uptake.

    Science.gov (United States)

    Isakoff, S J; Taha, C; Rose, E; Marcusohn, J; Klip, A; Skolnik, E Y

    1995-10-24

    Recent experimental evidence has focused attention to the role of two molecules, insulin receptor substrate 1 (IRS-1) and phosphatidylinositol 3-kinase (PI3-kinase), in linking the insulin receptor to glucose uptake; IRS-1 knockout mice are insulin resistant, and pharmacological inhibitors of PI3-kinase block insulin-stimulated glucose uptake. To investigate the role of PI3-kinase and IRS-1 in insulin-stimulated glucose uptake we examined whether stimulation of insulin-sensitive cells with platelet-derived growth factor (PDGF) or with interleukin 4 (IL-4) stimulates glucose uptake; the activated PDGF receptor (PDGFR) directly binds and activates PI3-kinase, whereas the IL-4 receptor (IL-4R) activates PI3-kinase via IRS-1 or the IRS-1-related molecule 4PS. We found that stimulation of 3T3-L1 adipocytes with PDGF resulted in tyrosine phosphorylation of the PDGFR and activation of PI3-kinase in these cells. To examine whether IL-4 stimulates glucose uptake, L6 myoblasts were engineered to overexpress GLUT4 as well as both chains of the IL-4R (L6/IL-4R/GLUT4); when these L6/IL-4R/GLUT4 myoblasts were stimulated with IL-4, IRS-1 became tyrosine phosphorylated and associated with PI3-kinase. Although PDGF and IL-4 can activate PI3-kinase in the respective cell lines, they do not possess insulin's ability to stimulate glucose uptake and GLUT4 translocation to the plasma membrane. These findings indicate that activation of PI3-kinase is not sufficient to stimulate GLUT4 translocation to the plasma membrane. We postulate that activation of a second signaling pathway by insulin, distinct from PI3-kinase, is necessary for the stimulation of glucose uptake in insulin-sensitive cells.

  6. Rac1 Activation Caused by Membrane Translocation of a Guanine Nucleotide Exchange Factor in Akt2-Mediated Insulin Signaling in Mouse Skeletal Muscle.

    Directory of Open Access Journals (Sweden)

    Nobuyuki Takenaka

    Full Text Available Insulin-stimulated glucose uptake in skeletal muscle is mediated by the glucose transporter GLUT4, which is translocated to the plasma membrane following insulin stimulation. Several lines of evidence suggested that the protein kinase Akt2 plays a key role in this insulin action. The small GTPase Rac1 has also been implicated as a regulator of insulin-stimulated GLUT4 translocation, acting downstream of Akt2. However, the mechanisms whereby Akt2 regulates Rac1 activity remain obscure. The guanine nucleotide exchange factor FLJ00068 has been identified as a direct regulator of Rac1 in Akt2-mediated signaling, but its characterization was performed mostly in cultured myoblasts. Here, we provide in vivo evidence that FLJ00068 indeed acts downstream of Akt2 as a Rac1 regulator by using mouse skeletal muscle. Small interfering RNA knockdown of FLJ00068 markedly diminished GLUT4 translocation to the sarcolemma following insulin administration or ectopic expression of a constitutively activated mutant of either phosphoinositide 3-kinase or Akt2. Additionally, insulin and these constitutively activated mutants caused the activation of Rac1 as shown by immunofluorescent microscopy using a polypeptide probe specific to activated Rac1 in isolated gastrocnemius muscle fibers and frozen sections of gastrocnemius muscle. This Rac1 activation was also abrogated by FLJ00068 knockdown. Furthermore, we observed translocation of FLJ00068 to the cell periphery following insulin stimulation in cultured myoblasts. Localization of FLJ00068 in the plasma membrane in insulin-stimulated, but not unstimulated, myoblasts and mouse gastrocnemius muscle was further affirmed by subcellular fractionation and subsequent immunoblotting. Collectively, these results strongly support a critical role of FLJ00068 in Akt2-mediated Rac1 activation in mouse skeletal muscle insulin signaling.

  7. A high-fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice.

    Science.gov (United States)

    Wong, Chi Kin; Botta, Amy; Pither, Jason; Dai, Chuanbin; Gibson, William T; Ghosh, Sanjoy

    2015-04-01

    Over the last few decades, polyunsaturated fatty acid (PUFA), especially n-6 PUFA, and monounsaturated fatty acid content in 'Western diets' has increased manyfold. Such a dietary shift also parallels rising sedentary behavior and diabetes in the Western world. We queried if a shift in dietary fats could be linked to physical inactivity and insulin insensitivity in mice. Eight-week old female C57/Bl6 mice were fed either high-fat (HF) diets [40% energy corn oil (CO) or isocaloric olive oil (OO) diets] or chow (n=10/group) for 6 weeks, followed by estimation of spontaneous locomotor activity, body composition and in vivo metabolic outcomes. Although lean mass and resting energy expenditure stayed similar in both OO- and CO-fed mice, only CO-fed mice demonstrated reduced spontaneous locomotor activity. Such depressed activity in CO-fed mice was accompanied by a lower respiratory ratio, hyperinsulinemia and impaired glucose disposal following intraperitoneal glucose tolerance and insulin tolerance tests compared to OO-fed mice. Unlike the liver, where both HF diets increased expression of fat oxidation genes like PPARs, the skeletal muscle of CO-fed mice failed to up-regulate such genes, thereby supporting the metabolic insufficiencies observed in these mice. In summary, this study demonstrates a specific contribution of n-6 PUFA-rich oils like CO to the loss of spontaneous physical activity and insulin sensitivity in mice. If these data hold true for humans, this study could provide a novel link between recent increases in dietary n-6 PUFA to sedentary behavior and the development of insulin resistance in the Western world.

  8. Insulin and insulin signaling play a critical role in fat induction of insulin resistance in mouse

    Science.gov (United States)

    Ning, Jie; Hong, Tao; Yang, Xuefeng; Mei, Shuang; Liu, Zhenqi; Liu, Hui-Yu

    2011-01-01

    The primary player that induces insulin resistance has not been established. Here, we studied whether or not fat can cause insulin resistance in the presence of insulin deficiency. Our results showed that high-fat diet (HFD) induced insulin resistance in C57BL/6 (B6) mice. The HFD-induced insulin resistance was prevented largely by the streptozotocin (STZ)-induced moderate insulin deficiency. The STZ-induced insulin deficiency prevented the HFD-induced ectopic fat accumulation and oxidative stress in liver and gastrocnemius. The STZ-induced insulin deficiency prevented the HFD- or insulin-induced increase in hepatic expression of long-chain acyl-CoA synthetases (ACSL), which are necessary for fatty acid activation. HFD increased mitochondrial contents of long-chain acyl-CoAs, whereas it decreased mitochondrial ADP/ATP ratio, and these HFD-induced changes were prevented by the STZ-induced insulin deficiency. In cultured hepatocytes, we observed that expressions of ACSL1 and -5 were stimulated by insulin signaling. Results in cultured cells also showed that blunting insulin signaling by the PI3K inhibitor LY-294002 prevented fat accumulation, oxidative stress, and insulin resistance induced by the prolonged exposure to either insulin or oleate plus sera that normally contain insulin. Finally, knockdown of the insulin receptor prevented the oxidative stress and insulin resistance induced by the prolonged exposure to insulin or oleate plus sera. Together, our results show that insulin and insulin signaling are required for fat induction of insulin resistance in mice and cultured mouse hepatocytes. PMID:21586696

  9. Proliferator-activated receptor gamma Pro12Ala interacts with the insulin receptor substrate 1 Gly972Arg and increase the risk of insulin resistance and diabetes in the mixed ancestry population from South Africa.

    Science.gov (United States)

    Vergotine, Zelda; Yako, Yandiswa Y; Kengne, Andre P; Erasmus, Rajiv T; Matsha, Tandi E

    2014-01-21

    The peroxisome proliferator-activated receptor gamma (PPARG), Pro12Ala and the insulin receptor substrate (IRS1), Gly972Arg confer opposite effects on insulin resistance and type 2 diabetes mellitus (T2DM). We investigated the independent and joint effects of PPARG Pro12Ala and IRS1 Gly972Arg on markers of insulin resistance and T2DM in an African population with elevated risk of T2DM. In all 787 (176 men) mixed-ancestry adults from the Bellville-South community in Cape Town were genotyped for PPARG Pro12Ala and IRS1 Gly972Arg by two independent laboratories. Glucose tolerance status and insulin resistance/sensitivity were assessed. Genotype frequencies were 10.4% (PPARG Pro12Ala) and 7.7% (IRS1 Gly972Arg). Alone, none of the polymorphisms predicted prevalent T2DM, but in regression models containing both alleles and their interaction term, PPARG Pro12 conferred a 64% higher risk of T2DM. Furthermore PPARG Pro12 was positively associated in adjusted linear regressions with increased 2-hour post-load insulin in non-diabetic but not in diabetic participants. The PPARG Pro12 is associated with insulin resistance and this polymorphism interacts with IRS1 Gly972Arg, to increase the risk of T2DM in the mixed-ancestry population of South Africa. Our findings require replication in a larger study before any generalisation and possible application for risk stratification.

  10. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats

    DEFF Research Database (Denmark)

    Brandt, Nina; De Bock, Katrien; Richter, Erik

    2010-01-01

    Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptation are not known, and it is also not known whether exercise training can reverse it. Male Wistar rats were assigned...... was counteracted by training. In the perfused hindlimb, insulin-stimulated glucose transport in red gastrocnemius muscle was completely abolished in CAF and rescued by exercise training. Apart from a tendency toward an approximately 20% reduction in both basal and insulin-stimulated Akt Ser(473) phosphorylation (P......) among the groups. In conclusion, surplus energy intake of a palatable but low-fat cafeteria diet resulted in obesity and insulin resistance that was rescued by exercise training. Interestingly, insulin resistance was not accompanied by major defects in the insulin-signaling cascade or in altered AMPK...

  11. Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats.

    Science.gov (United States)

    Brandt, Nina; De Bock, Katrien; Richter, Erik A; Hespel, Peter

    2010-08-01

    Excess energy intake via a palatable low-fat diet (cafeteria diet) is known to induce obesity and glucose intolerance in rats. However, the molecular mechanisms behind this adaptation are not known, and it is also not known whether exercise training can reverse it. Male Wistar rats were assigned to 12-wk intervention groups: chow-fed controls (CON), cafeteria diet (CAF), and cafeteria diet plus swimming exercise during the last 4 wk (CAF(TR)). CAF feeding led to increased body weight (16%, P cafeteria diet resulted in obesity and insulin resistance that was rescued by exercise training. Interestingly, insulin resistance was not accompanied by major defects in the insulin-signaling cascade or in altered AMPK expression or phosphorylation. Thus, compared with previous studies of high-fat feeding, where insulin signaling is significantly impaired, the mechanism by which CAF diet induces insulin resistance seems different.

  12. Design of an active ultrastable single-chain insulin analog: synthesis, structure, and therapeutic implications.

    Science.gov (United States)

    Hua, Qing-xin; Nakagawa, Satoe H; Jia, Wenhua; Huang, Kun; Phillips, Nelson B; Hu, Shi-quan; Weiss, Michael A

    2008-05-23

    Single-chain insulin (SCI) analogs provide insight into the inter-relation of hormone structure, function, and dynamics. Although compatible with wild-type structure, short connecting segments (design, structure, and function of a single-chain insulin analog (SCI-57) containing a 6-residue linker (GGGPRR). Native receptor-binding affinity (130 +/- 8% relative to the wild type) is achieved as hindrance by the linker is offset by favorable substitutions in the insulin moiety. The thermodynamic stability of SCI-57 is markedly increased (DeltaDeltaG(u) = 0.7 +/- 0.1 kcal/mol relative to the corresponding two-chain analog and 1.9 +/- 0.1 kcal/mol relative to wild-type insulin). Analysis of inter-residue nuclear Overhauser effects demonstrates that a native-like fold is maintained in solution. Surprisingly, the glycine-rich connecting segment folds against the insulin moiety: its central Pro contacts Val(A3) at the edge of the hydrophobic core, whereas the final Arg extends the A1-A8 alpha-helix. Comparison between SCI-57 and its parent two-chain analog reveals striking enhancement of multiple native-like nuclear Overhauser effects within the tethered protein. These contacts are consistent with wild-type crystal structures but are ordinarily attenuated in NMR spectra of two-chain analogs, presumably due to conformational fluctuations. Linker-specific damping of fluctuations provides evidence for the intrinsic flexibility of an insulin monomer. In addition to their biophysical interest, ultrastable SCIs may enhance the safety and efficacy of insulin replacement therapy in the developing world.

  13. Comparison Between Individually and Group-Based Insulin Pump Initiation by Time-Driven Activity-Based Costing.

    Science.gov (United States)

    Ridderstråle, Martin

    2017-07-01

    Depending on available resources, competencies, and pedagogic preference, initiation of insulin pump therapy can be performed on either an individual or a group basis. Here we compared the two models with respect to resources used. Time-driven activity-based costing (TDABC) was used to compare initiating insulin pump treatment in groups (GT) to individual treatment (IT). Activities and cost drivers were identified, timed, or estimated at location. Medical quality and patient satisfaction were assumed to be noninferior and were not measured. GT was about 30% less time-consuming and 17% less cost driving per patient and activity compared to IT. As a batch driver (16 patients in one group) GT produced an upward jigsaw-shaped accumulative cost curve compared to the incremental increase incurred by IT. Taking the alternate cost for those not attending into account, and realizing the cost of opportunity gained, suggested that GT was cost neutral already when 5 of 16 patients attended, and that a second group could be initiated at no additional cost as the attendance rate reached 15:1. We found TDABC to be effective in comparing treatment alternatives, improving cost control and decision making. Everything else being equal, if the setup is available, our data suggest that initiating insulin pump treatment in groups is far more cost effective than on an individual basis and that TDABC may be used to find the balance point.

  14. Coordination of insulin and Notch pathway activities by microRNA miR-305 mediates adaptive homeostasis in the intestinal stem cells of the Drosophila gut.

    Science.gov (United States)

    Foronda, David; Weng, Ruifen; Verma, Pushpa; Chen, Ya-Wen; Cohen, Stephen M

    2014-11-01

    Homeostasis of the intestine is maintained by dynamic regulation of a pool of intestinal stem cells. The balance between stem cell self-renewal and differentiation is regulated by the Notch and insulin signaling pathways. Dependence on the insulin pathway places the stem cell pool under nutritional control, allowing gut homeostasis to adapt to environmental conditions. Here we present evidence that miR-305 is required for adaptive homeostasis of the gut. miR-305 regulates the Notch and insulin pathways in the intestinal stem cells. Notably, miR-305 expression in the stem cells is itself under nutritional control via the insulin pathway. This link places regulation of Notch pathway activity under nutritional control. These findings provide a mechanism through which the insulin pathway controls the balance between stem cell self-renewal and differentiation that is required for adaptive homeostasis in the gut in response to changing environmental conditions.

  15. COPD exacerbations, inflammation and treatment

    NARCIS (Netherlands)

    Bathoorn, Derk

    2007-01-01

    This thesis describes investigations into the inflammation in COPD, and its treatment. Inflammation in COPD is a central factor in the onset of the disease and its progression. During acute deteriorations of the disease, exacerbations, the inflammation is more severe, and depending on the cause of t

  16. The relation between platelet activation and hypercoagulability in elderly patients with chronic cor pulmonary exacerbation%血小板活性与老年慢性肺心病高凝状态的关系

    Institute of Scientific and Technical Information of China (English)

    邬伟明; 谭劼; 郭永谊; 黄瑾

    2009-01-01

    Objective:To investigate the relation among platelet activation marker(GPⅡb/Ⅲa,CD62p) and amounts of fibrinogen (FG) and of D-dimer (DD) in elderly patients with chronic cor pulmonale exacerbation.Methods:Subjects were divided into four groups (42 elderly patients with chronic cor pulmonale exacerbation,42 elderly patients with chronic cor pulmonale remission stage,30cases of healthy elderly controls and 30 cases of healthy non-elderly controls).Positive rates of GPⅡb/Ⅲa and CD62p were measured with tricolor flow cytometry.We also determined FG and DD in patients with chronic cor pulmonale and in normal controls.Results:Compared with those of chronic cor pulmonale remission stage group,healthy elderly group and healthy non-elderly group,the levels of GPⅡb/Ⅲa,CD62p,FG and DD increased significantly in elderly patients with chronic cor pulmonale exacerbation (all P<0.001).There was a positive correlation between the amount of GPⅡb/Ⅲa or CD62p and the amount of FG and DD in elderly patients with chronic cor pulmonale exacerbation.Conclusion:There is increased coagulation and platelet activity in elderly patients with chronic cor pulmonale exacerbation,and there is a significant correlation between platelet activity and hypercoagulability.%目的:探讨老年慢性肺心病急性加重期患者血小板膜糖蛋白GPⅡb/Ⅲa、CD62p的变化与纤维蛋白原(FG)、D-二聚体(DD)的关系.方法:用三色全血流式细胞术测定42例老年慢性肺心病急性加重期患者及42例缓解期患者外周血中血小板GPⅡb/Ⅲa、CD62p的表达水平,并检测患者FG、DD水平,与30例老年健康对照者及30例非老年健康对照者比较.结果:老年慢性肺心病急性加重期组GPⅡb/Ⅲa、CD62p、FG、DD均明显高于缓解期组、老年健康对照组及非老年健康对照组(均P<0.001).老年慢性肺心病急性加重期组GPⅡb/Ⅲa、CD62p与FG、DD均呈正相关.结论:老年慢性肺心病急性加重期患

  17. Fuel-Stimulated Insulin Secretion Depends upon Mitochondria Activation and the Integration of Mitochondrial and Cytosolic Substrate Cycles

    Directory of Open Access Journals (Sweden)

    Gary W. Cline

    2011-10-01

    Full Text Available The pancreatic islet β-cell is uniquely specialized to couple its metabolism and rates of insulin secretion with the levels of circulating nutrient fuels, with the mitochondrial playing a central regulatory role in this process. In the β-cell, mitochondrial activation generates an integrated signal reflecting rates of oxidativephosphorylation, Kreb's cycle flux, and anaplerosis that ultimately determines the rate of insulin exocytosis. Mitochondrial activation can be regulated by proton leak and mediated by UCP2, and by alkalinization to utilize the pH gradient to drive substrate and ion transport. Converging lines of evidence support the hypothesis that substrate cycles driven by rates of Kreb's cycle flux and by anaplerosis play an integral role in coupling responsive changes in mitochondrial metabolism with insulin secretion. The components and mechanisms that account for the integrated signal of ATP production, substrate cycling, the regulation of cellular redox state, and the production of other secondary signaling intermediates are operative in both rodent and human islet β-cells.

  18. Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways

    Directory of Open Access Journals (Sweden)

    Chae Eun Lee

    2012-01-01

    Full Text Available This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda H. Hara on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG, T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation.

  19. Hepatic histomorphological and biochemical changes following highly active antiretroviral therapy in an experimental animal model: Does Hypoxis hemerocallidea exacerbate hepatic injury?

    Directory of Open Access Journals (Sweden)

    Onyemaechi Okpara Azu

    2016-01-01

    While no mortality was reported, animals treated with adjuvant HAART and AP recorded least% body weight gain. Significant derangements in serum lipid profiles were exacerbated by treatment of with AP as LDL (increased p < 0.03, triglycerides (increased p < 0.03 with no change in total cholesterol levels. Adjuvant AP with HAART caused reduction in LDL (p < 0.05 and 0.03, increased HDL (p < 0.05 and TG (p < 0.05 and 0.001 for AP100 and AP200 doses respectively. Markers of liver injury assayed showed significant increase (p < 0.003, 0.001 in AST in AP alone as well as HAART+ vitamins C and E groups respectively. Adjuvant HAART and AP and vitamins C and E also caused significant declines in ALT and ALP levels. Serum GGT was not markedly altered. Disturbances in histopathology ranged from severe hepatocellular distortions, necrosis and massive fibrosis following co-treatment of HAART with vitamins C and E as well as HAART alone. These results warrant caution on the adjuvant use of AP with HAART by PLWHAs as implications for hepatocellular injuries are suspect with untoward cardiometabolic changes.

  20. Effect of insulin analogues on insulin/IGF1 hybrid receptors: increased activation by glargine but not by its metabolites M1 and M2.

    Directory of Open Access Journals (Sweden)

    Cécile Pierre-Eugene

    Full Text Available BACKGROUND: In diabetic patients, the pharmacokinetics of injected human insulin does not permit optimal control of glycemia. Fast and slow acting insulin analogues have been developed, but they may have adverse properties, such as increased mitogenic or anti-apoptotic signaling. Insulin/IGF1 hybrid receptors (IR/IGF1R, present in most tissues, have been proposed to transmit biological effects close to those of IGF1R. However, the study of hybrid receptors is difficult because of the presence of IR and IGF1R homodimers. Our objective was to perform the first study on the pharmacological properties of the five marketed insulin analogues towards IR/IGF1R hybrids. METHODOLOGY: To study the effect of insulin analogues on IR/IGF1R hybrids, we used our previously developed Bioluminescence Resonance Energy Transfer (BRET assay that permits specific analysis of the pharmacological properties of hybrid receptors. Moreover, we have developed a new, highly sensitive BRET-based assay to monitor phophatidylinositol-3 phosphate (PIP(3 production in living cells. Using this assay, we performed a detailed pharmacological analysis of PIP(3 production induced by IGF1, insulin and insulin analogues in living breast cancer-derived MCF-7 and MDA-MB231 cells. RESULTS: Among the five insulin analogues tested, only glargine stimulated IR/IGF1R hybrids with an EC50 that was significantly lower than insulin and close to that of IGF1. Glargine more efficiently stimulated PIP(3 production in MCF-7 cells but not in MDA-MB231 cells as compared to insulin. In contrast, glargine metabolites M1 and M2 showed lower potency for hybrid receptors stimulation, PIP(3 production, Akt and Erk1/2 phosphorylation and DNA synthesis in MCF-7 cells, compared to insulin. CONCLUSION: Glargine, possibly acting through IR/IGF1R hybrids, displays higher potency, whereas its metabolites M1 and M2 display lower potency than insulin for the stimulation of proliferative/anti-apoptotic pathways in

  1. Physical activity in overweight and obese pregnant women is associated with higher levels of proinflammatory cytokines and with reduced insulin response through interleukin-6.

    Science.gov (United States)

    van Poppel, Mireille N M; Peinhaupt, Miriam; Eekhoff, Marelise E W; Heinemann, Akos; Oostdam, Nicolette; Wouters, Maurice G A J; van Mechelen, Willem; Desoye, Gernot

    2014-04-01

    OBJECTIVE Previously, we reported the positive association of moderate-to-vigorous physical activity (MVPA) with insulin sensitivity in overweight and obese pregnant women. We sought to assess whether these MVPA-induced changes in insulin sensitivity are mediated by changes in interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and IL-1β. RESEARCH DESIGN AND METHODS A prospective longitudinal study was conducted in 46 overweight and obese women at risk for gestational diabetes mellitus. Objective physical activity measurements and fasting blood samples were taken at 15, 24, and 32 weeks of pregnancy. At 24 and 32 weeks, a 100-g oral glucose test was performed in addition. Cytokines, C-reactive protein, and glucose and insulin levels were measured, and insulin sensitivity and first-phase insulin response were calculated. Relationships between the different parameters were assessed using linear regression models, adjusting for maternal age and BMI. RESULTS All cytokines were elevated in women with higher levels of MVPA at 15 weeks of gestation. Higher IL-6 was related to a lower first-phase insulin response (β -810.5 [95% CI -1,524.5 to -96.5]; P = 0.03). TNF-α and IL-1β had different effects in women with low MVPA (with low IL-6 levels) compared with more active women. CRP was not related to MVPA. CONCLUSIONS The association of MVPA with insulin sensitivity and first-phase insulin response may be (partly) mediated by IL-6, since this cytokine was related to reduced first-phase insulin response. The possible positive effects of the elevated cytokine profile in active obese pregnant women warrant further study.

  2. Abdominal obesity as a mediator of the influence of physical activity on insulin resistance in Spanish adults.

    Science.gov (United States)

    García-Hermoso, Antonio; Martínez-Vizcaíno, Vicente; Recio-Rodriguez, Jose I; Díez-Fernández, Ana; Gómez-Marcos, Manuel A; García-Ortiz, Luis

    2016-01-01

    The aim of the study was to analyze the relationship between moderate-to-vigorous physical activity (MVPA) and insulin resistance (IR) in Spanish adults and to examine whether this relationship is mediated by abdominal obesity (waist circumference - WC). The cross-sectional study included 1162 healthy subjects belonging to the EVIDENT study (mean age 55.0±13.3years; 61.8% women) from six different Spanish provinces. Moderate-to-vigorous physical activity (MVPA) was measured objectively over 7days using Actigraph accelerometers, collecting data in 60-second epochs, and retaining respondents with ≥4 valid days for the analysis. The homeostasis model of assessment (HOMA-IR) was used to determine IR, and its individual components - fasting glucose and insulin - were determined using standard protocols. Linear regression models were fitted according to Baron and Kenny's procedures for mediation analysis. Fasting insulin and HOMA-IR levels were significantly worse in adults who spent fewer minutes in MVPA (first quartile≤30.1 and 22.7min/day in men and women, respectively) after adjusting for age, sex, smoking habits, drinking habits, accelerometer wear time, sedentary time, and Mediterranean diet adherence. However, when WC was added to the ANCOVA models as a covariate, the effects disappeared. Mediation analysis reported that WC acts as a full mediator in the relationship between MVPA and IR (HOMA-IR and fasting insulin). These findings show that WC plays a pivotal role in the relationship between MVPA and IR, and therefore highlights that decreasing abdominal obesity might be considered as an intermediate outcome for evaluating interventions aimed at preventing diabetes mellitus. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Predicting an asthma exacerbation in children 2 to 5 years of age

    DEFF Research Database (Denmark)

    Swern, Arlene S; Tozzi, Carol A; Knorr, Barbara;

    2008-01-01

    an exacerbation. Caregiver-reported information (daytime cough, breathing difficulties, limitation of activity, nighttime cough or awakening, daytime and nighttime beta2-agonist use) were analyzed using general estimating equations with an exchangeable within-subject log odds ratio regression structure...... to identify predictors of an exacerbation. RESULTS: Average symptom scores and beta2-agonist use increased significantly before exacerbation but at different rates. A combination of daytime cough and wheeze and nighttime beta2-agonist use 1 day before the exacerbation was identified as strongly predictive...... of an exacerbation. These methods predicted 149 (66.8%) of the exacerbations with a very low false-positive rate of 14.2%. CONCLUSIONS: No individual symptom was predictive of an imminent asthma exacerbation, but a combination of increased daytime cough, daytime wheeze, and nighttime beta2-agonist use 1 day before...

  4. Effect of resistance exercise under conditions of reduced blood insulin on AMPKα Ser485/491 inhibitory phosphorylation and AMPK pathway activation.

    Science.gov (United States)

    Kido, Kohei; Yokokawa, Takumi; Ato, Satoru; Sato, Koji; Fujita, Satoshi

    2017-08-01

    Insulin stimulates skeletal muscle glucose uptake via activation of the protein kinase B/Akt (Akt) pathway. Recent studies suggest that insulin downregulates AMP-activated protein kinase (AMPK) activity via Ser485/491 phosphorylation of the AMPK α-subunit. Thus lower blood insulin concentrations may induce AMPK signal activation. Acute exercise is one method to stimulate AMPK activation; however, no study has examined the relationship between blood insulin levels and acute resistance exercise-induced AMPK pathway activation. Based on previous findings, we hypothesized that the acute resistance exercise-induced AMPK pathway activation would be augmented by disruptions in insulin secretion through a decrease in AMPKα Ser485/491 inhibitory phosphorylation. To test the hypothesis, 10-wk-old male Sprague-Dawley rats were administered the toxin streptozotocin (STZ; 55 mg/kg) to destroy the insulin secreting β-cells. Three days postinjection, the right gastrocnemius muscle from STZ and control rats was subjected to resistance exercise by percutaneous electrical stimulation. Animals were killed 0, 1, or 3 h later; activation of the Akt/AMPK and downstream pathways in the muscle tissue was analyzed by Western blotting and real-time PCR. Notably, STZ rats showed a significant decrease in basal Akt and AMPKα Ser485/491 phosphorylation, but substantial exercise-induced increases in both AMPKα Thr172 and acetyl-CoA carboxylase (ACC) Ser79 phosphorylation were observed. Although no significant impact on resistance exercise-induced Akt pathway activation or glucose uptake was found, resistance exercise-induced peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1 α (PGC-1α) gene expression was augmented by STZ treatment. Collectively, these data suggest that circulating insulin levels may regulate acute resistance exercise-induced AMPK pathway activation and AMPK-dependent gene expression relating to basal AMPKα Ser485/491 phosphorylation. Copyright © 2017

  5. Growth hormone regulation of p85alpha expression and phosphoinositide 3-kinase activity in adipose tissue: mechanism for growth hormone-mediated insulin resistance.

    Science.gov (United States)

    del Rincon, Juan-Pablo; Iida, Keiji; Gaylinn, Bruce D; McCurdy, Carrie E; Leitner, J Wayne; Barbour, Linda A; Kopchick, John J; Friedman, Jacob E; Draznin, Boris; Thorner, Michael O

    2007-06-01

    Phosphoinositide (PI) 3-kinase is involved in insulin-mediated effects on glucose uptake, lipid deposition, and adiponectin secretion from adipocytes. Genetic disruption of the p85alpha regulatory subunit of PI 3-kinase increases insulin sensitivity, whereas elevated p85alpha levels are associated with insulin resistance through PI 3-kinase-dependent and -independent mechanisms. Adipose tissue plays a critical role in the antagonistic effects of growth hormone (GH) on insulin actions on carbohydrate and lipid metabolism through changes in gene transcription. The objective of this study was to assess the role of the p85alpha subunit of PI 3-kinase and PI 3-kinase signaling in GH-mediated insulin resistance in adipose tissue. To do this, p85alpha mRNA and protein expression and insulin receptor substrate (IRS)-1-associated PI 3-kinase activity were measured in white adipose tissue (WAT) of mice with GH excess, deficiency, and sufficiency. Additional studies using 3T3-F442A cells were conducted to confirm direct effects of GH on free p85alpha protein abundance. We found that p85alpha expression 1) is decreased in WAT from mice with isolated GH deficiency, 2) is increased in WAT from mice with chronic GH excess, 3) is acutely upregulated in WAT from GH-deficient and -sufficient mice after GH administration, and 4) is directly upregulated by GH in 3T3-F442A adipocytes. The insulin-induced increase in PI 3-kinase activity was robust in mice with GH deficiency, but not in mice with GH excess. In conclusion, GH regulates p85alpha expression and PI 3-kinase activity in WAT and provides a potential explanation for 1) the insulin hypersensitivity and associated obesity and hyperadiponectinemia of GH-deficient mice and 2) the insulin resistance and associated reduced fat mass and hypoadiponectinemia of mice with GH excess.

  6. Comparison of in vivo effects of insulin on SREBP-1c activation and INSIG-1/2 in rat liver and human and rat adipose tissue.

    Science.gov (United States)

    Boden, Guenther; Salehi, Sajad; Cheung, Peter; Homko, Carol; Song, Weiwei; Loveland-Jones, Catherine; Jayarajan, Senthil

    2013-06-01

    The stimulatory effects of insulin on de novo lipogenesis (DNL) in the liver, where it is an important contributor to non-alcoholic fatty liver disease (NAFLD), hepatic and systemic insulin resistance, is strong and well established. In contrast, insulin plays only a minor role in DNL in adipose tissue. The reason why insulin stimulates DNL more in liver than in fat is not known but may be due to differential regulation of the transcription and post-translational activation of sterol regulatory element binding proteins (SREBPs). To test this hypothesis, we have examined effects of insulin on activation of SREBP-1c in liver of rats and in adipose tissue of rats and human subjects. Liver and epidydimal fat were obtained from alert rats and subcutaneous adipose tissue from human subjects in response to 4 h euglycemic-hyperinsulinemic clamps. Here we show that acutely raising plasma insulin levels in rats and humans increased SREBP-1 mRNA comparably 3-4 fold in rat liver and rat and human adipose tissue, but increased post-translational activation of SREBP-1c only in rat liver, while decreasing it in adipose tissue. These differential effects of insulin on SREBP-1c activation in liver and adipose tissue were associated with robust changes in the opposite direction of INSIG-1 and to a lesser extent of INSIG-2 mRNA and proteins. We conclude that these findings support the hypothesis that insulin stimulated activation of SREBP-1c in the liver, at least in part, by suppressing INSIG-1 and -2, whereas in adipose tissue, an increase in INSIG-1 and -2 prevented SREBP-1c activation. Copyright © 2012 The Obesity Society.

  7. Comparison of In Vivo Effects of Insulin on SREBP-1c Activation and INSIG-1/2 in Rat Liver and Human and Rat Adipose Tissue

    Science.gov (United States)

    Boden, Guenther; Salehi, Sajad; Cheung, Peter; Homko, Carol; Song, Weiwei; Loveland-Jones, Catherine; Jayarajan, Senthil

    2012-01-01

    The stimulatory effects of insulin on de novo lipogenesis (DNL) in the liver, where it is an important contributor to non-alcoholic fatty liver disease (NAFLD), hepatic and systemic insulin resistance, is strong and well established. In contrast, insulin plays only a minor role in DNL in adipose tissue. The reason why insulin stimulates DNL more in liver than in fat is not known but may be due to differential regulation of the transcription and post-translational activation of sterol regulatory element binding proteins (SREBPs). To test this hypothesis, we have examined effects of insulin on activation of SREBP-1c in liver of rats and in adipose tissue of rats and human subjects. Liver and epidydimal fat were obtained from alert rats and subcutaneous adipose tissue from human subjects in response to 4 h euglycemic-hyperinsulinemic clamps. Here we show that acutely raising plasma insulin levels in rats and humans increased SREBP-1 mRNA comparably 3-4 fold in rat liver and rat and human adipose tissue, but increased post-translational activation of SREBP-1c only in rat liver, while decreasing it in adipose tissue. These differential effects of insulin on SREBP-1c activation in liver and adipose tissue were associated with robust changes in the opposite direction of INSIG-1 and to a lesser extent of INSIG-2 mRNA and proteins. We conclude that these findings support the hypothesis that insulin stimulated activation of SREBP-1c in the liver, at least in part, by suppressing INSIG-1 and -2, whereas in adipose tissue, an increase in INSIG-1 and -2 prevented SREBP-1c activation. PMID:23913732

  8. PACAP stimulates insulin secretion but inhibits insulin sensitivity in mice

    NARCIS (Netherlands)

    Filipsson, K; Pacini, G; Scheurink, AJW; Ahren, B

    Although pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates insulin secretion, its net influence on glucose homeostasis in vivo has not been established. We therefore examined the action of PACAP-27 and PACAP-38 on insulin secretion, insulin sensitivity, and glucose disposal as

  9. Insulin-like growth factor binding protein-I-6 expression in activated microglia

    NARCIS (Netherlands)

    Chesik, D.; Glazenburg, K.; Wilczak, N.; Geeraedts, Felix; De Keyser, J.

    2004-01-01

    In the CNS insulin-like growth factor-1 (IGF-1) enhances survival of neurons, promotes myelin synthesis and acts as a mitogen for microglia. The effects of IGF-1 are regulated by a family of 6 IGF binding proteins (IGFBPs). We investigated mRNA expression patterns of IGFBPs in primary rat microglia

  10. The inflammasome-mediated caspase-1 activation controls adipocyte differentiation and insulin sensitivity

    NARCIS (Netherlands)

    Stienstra, R.; Joosten, L.A.; Koenen, T.; Tits, van B.; Diepen, van J.A.; Berg, van den S.A.A.; Rensen, P.C.; Voshol, P.J.; Fantuzzi, G.; Hijmans, A.; Kersten, A.H.; Müller, M.R.; Berg, van den W.B.; Rooijen, van N.; Wabitsch, M.; Kullberg, B.J.; Meer, van der J.W.; Kanneganti, T.; Tack, C.J.; Netea, M.G.

    2010-01-01

    Obesity-induced inflammation originating from expanding adipose tissue interferes with insulin sensitivity. Important metabolic effects have been recently attributed to IL-1ß and IL-18, two members of the IL-1 family of cytokines. Processing of IL-1ß and IL-18 requires cleavage by caspase-1, a

  11. Antibiotics usefulness and choice in BPCO acute exacerbation

    Directory of Open Access Journals (Sweden)

    Bruno Tartaglino

    2005-10-01

    Full Text Available Although the debate on the role of bacterial infections and antibiotic treatment in AE-COPD remains open, there is evidence that the persistence of bacteria after acute exacerbation (residual bacterial colony influences the frequency and severity of subsequent acute exacerbation and that antibiotic treatment that induces faster and more complete eradication produces better clinical outcomes. New aspects must now be considered, given that COPD is a chronic illness subject to acute exacerbations of varying frequencies and that acute exacerbations correspond to functional respiratory deterioration. One of the parameters that is currently acquiring clinical relevance is the interval free of infection (IFI, the period that elapses between one acute exacerbation and the next, caused by bacterial infection. Another guiding concept in the choice of antibiotic treatment is that not all patients benefit in the same way; those requiring more aggressive treatment are most likely to be those with FEV1 < 50%, frequent exacerbations (> 3/year treated with antibiotics, relevant co-morbidity, under chronic steroid treatment, etc., for these patients it is recommended to administer antibiotics active on the three most common pathogens (in particular H. influenzae, considering the resistance acquired in recent years, and on Pseudomomias aeruginosa.

  12. Unacylated ghrelin rapidly modulates lipogenic and insulin signaling pathway gene expression in metabolically active tissues of GHSR deleted mice.

    Directory of Open Access Journals (Sweden)

    Patric J D Delhanty

    Full Text Available BACKGROUND: There is increasing evidence that unacylated ghrelin (UAG improves insulin sensitivity and glucose homeostasis; however, the mechanism for this activity is not fully understood since a UAG receptor has not been discovered. METHODOLOGY/PRINCIPAL FINDINGS: To assess potential mechanisms of UAG action in vivo, we examined rapid effects of UAG on genome-wide expression patterns in fat, muscle and liver of growth hormone secretagogue receptor (GHSR-ablated mice using microarrays. Expression data were analyzed using Ingenuity Pathways Analysis and Gene Set Enrichment Analysis. Regulation of subsets of these genes was verified by quantitative PCR in an independent experiment. UAG acutely regulated clusters of genes involved in glucose and lipid metabolism in all three tissues, consistent with enhancement of insulin sensitivity. CONCLUSIONS/SIGNIFICANCE: Fat, muscle and liver are central to the control of lipid and glucose homeostasis. UAG rapidly modulates the expression of metabolically important genes in these tissues in GHSR-deleted mice indicating a direct, GHSR-independent, action of UAG to improve insulin sensitivity and metabolic profile.

  13. PPARgamma activation attenuates T-lymphocyte-dependent inflammation of adipose tissue and development of insulin resistance in obese mice

    Directory of Open Access Journals (Sweden)

    Unger Thomas

    2010-10-01

    Full Text Available Abstract Background Inflammation of adipose tissue (AT has been recently accepted as a first step towards obesity-mediated insulin resistance. We could previously show that mice fed with high fat diet (HFD develop systemic insulin resistance (IR and glucose intolerance (GI associated with CD4-positive T-lymphocyte infiltration into visceral AT. These T-lymphocytes, when enriched in AT, participate in the development of fat tissue inflammation and subsequent recruitment of proinflammatory macrophages. The aim of this work was to elucidate the action of the insulin sensitizing PPARgamma on T-lymphocyte infiltration during development of IR, and comparison of the PPARgamma-mediated anti-inflammatory effects of rosiglitazone and telmisartan in diet-induced obesity model (DIO-model in mice. Methods In order to investigate the molecular mechanisms underlying early development of systemic insulin resistance and glucose intolerance male C57BL/6J mice were fed with high fat diet (HFD for 10-weeks in parallel to the pharmacological intervention with rosiglitazone, telmisartan, or vehicle. Results Both rosiglitazone and telmisartan were able to reduce T-lymphocyte infiltration into AT analyzed by quantitative analysis of the T-cell marker CD3gamma and the chemokine SDF1alpha. Subsequently, both PPARgamma agonists were able to attenuate macrophage infiltration into AT, measured by the reduction of MCP1 and F4/80 expression. In parallel to the reduction of AT-inflammation, ligand-activated PPARgamma improved diet-induced IR and GI. Conclusion Together the present study demonstrates a close connection between PPARgamma-mediated anti-inflammation in AT and systemic improvement of glucose metabolism identifying T-lymphocytes as one cellular mediator of PPARgamma´s action.

  14. Insulin induces a transcriptional activation of epiregulin, HB-EGF and amphiregulin, by a PI3K-dependent mechanism: identification of a specific insulin-responsive promoter element

    DEFF Research Database (Denmark)

    Ornskov, Dorthe; Nexo, Ebba; Sørensen, Boe Sandahl

    2007-01-01

    Previously we have shown that insulin-stimulation of RT4 bladder cancer cells leads to increased proliferation, which require HER1 activation, and is accompanied by increased mRNA expression of the EGF-ligands heparin-binding EGF-like growth factor (HB-EGF), amphiregulin (AR), and epiregulin (EPI...

  15. Drosophila insulin and target of rapamycin (TOR pathways regulate GSK3 beta activity to control Myc stability and determine Myc expression in vivo

    Directory of Open Access Journals (Sweden)

    Parisi Federica

    2011-09-01

    Full Text Available Abstract Background Genetic studies in Drosophila melanogaster reveal an important role for Myc in controlling growth. Similar studies have also shown how components of the insulin and target of rapamycin (TOR pathways are key regulators of growth. Despite a few suggestions that Myc transcriptional activity lies downstream of these pathways, a molecular mechanism linking these signaling pathways to Myc has not been clearly described. Using biochemical and genetic approaches we tried to identify novel mechanisms that control Myc activity upon activation of insulin and TOR signaling pathways. Results Our biochemical studies show that insulin induces Myc protein accumulation in Drosophila S2 cells, which correlates with a decrease in the activity of glycogen synthase kinase 3-beta (GSK3β a kinase that is responsible for Myc protein degradation. Induction of Myc by insulin is inhibited by the presence of the TOR inhibitor rapamycin, suggesting that insulin-induced Myc protein accumulation depends on the activation of TOR complex 1. Treatment with amino acids that directly activate the TOR pathway results in Myc protein accumulation, which also depends on the ability of S6K kinase to inhibit GSK3β activity. Myc upregulation by insulin and TOR pathways is a mechanism conserved in cells from the wing imaginal disc, where expression of Dp110 and Rheb also induces Myc protein accumulation, while inhibition of insulin and TOR pathways result in the opposite effect. Our functional analysis, aimed at quantifying the relative contribution of Myc to ommatidial growth downstream of insulin and TOR pathways, revealed that Myc activity is necessary to sustain the proliferation of cells from the ommatidia upon Dp110 expression, while its contribution downstream of TOR is significant to control the size of the ommatidia. Conclusions Our study presents novel evidence that Myc activity acts downstream of insulin and TOR pathways to control growth in Drosophila. At

  16. Treatment after a COPD exacerbation

    Directory of Open Access Journals (Sweden)

    Robbins RA

    2013-07-01

    Full Text Available No abstract available. Article truncated at 150 words. A couple of years ago I was consulted about a patient at the Phoenix VA who had been admitted for the third time for a COPD exacerbation in two months. Each time the patient was treated with inhaled short-acting bronchodilators, corticosteroids and an antibiotic; rapidly improved; and was discharged after only one or two days in the hospital. The discharge medications were albuterol, ipratropium, and rapidly tapering doses of prednisone. Apparently, no consideration was given to adding long-acting beta agonists (LABA, long-acting muscarinic antagonists (LAMA, and/or inhaled corticosteroids (ICS. These later medications have been shown to reduce exacerbations in most studies (1,2. I was reminded of this incident by a recent article published by Melzer et al. in the Journal of Internal Medicine (3. The authors examined 2760 patients with exacerbations of COPD admitted to hospitals in the VA Northwest Health Network (VISN 20 to determine if a LABA and/or …

  17. c-Jun NH2-terminal kinase activity in subcutaneous adipose tissue but not nuclear factor-kappaB activity in peripheral blood mononuclear cells is an independent determinant of insulin resistance in healthy individuals

    DEFF Research Database (Denmark)

    Sourris, Karly C; Lyons, Jasmine G; de Courten, Maximilian

    2009-01-01

    Chronic low-grade activation of the immune system (CLAIS) predicts type 2 diabetes via a decrease in insulin sensitivity. Our study investigated potential relationships between nuclear factor-kappaB (NF-kappaB) and c-Jun NH(2)-terminal kinase (JNK) pathways-two pathways proposed as the link between...... CLAIS and insulin resistance....

  18. Effects of Acute Pinitol Supplementation on Plasma Pinitol Concentration, Whole Body Glucose Tolerance, and Activation of the Skeletal Muscle Insulin Receptor in Older Humans

    OpenAIRE

    Stull, A. J.; Wood, K V; Thyfault, J. P.; Campbell, W.W.

    2009-01-01

    Limited research with rodents and humans suggests that oral ingestion of pinitol (3-O-methyl-d-chiro-inositol) might positively influence glucose tolerance. This double-blinded, placebo-controlled, and cross-over study assessed the effects of acute pinitol supplementation on plasma pinitol concentration, glucose tolerance, insulin sensitivity, and activation of the skeletal muscle insulin receptor. Fifteen older, nondiabetic subjects (62 ± 1 years, mean ± SEM) completed four, 1-day trials. Su...

  19. Accelerated extracellular matrix turnover during exacerbations of COPD

    DEFF Research Database (Denmark)

    Sand, Jannie M B; Knox, Alan J; Lange, Peter

    2015-01-01

    BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) contribute significantly to disease progression. However, the effect on tissue structure and turnover is not well described. There is an urgent clinical need for biomarkers of disease activity associated with disease...... progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD. METHODS: 69 patients with COPD hospitalised......, respectively), and degradation of elastin (ELM7 and EL-NE) and versican (VCANM). RESULTS: Circulating levels of C3M, C4M, C6M, ELM7, and EL-NE were elevated during an exacerbation of COPD as compared to follow-up (all P

  20. AMPK Activation by Metformin Suppresses Abnormal Extracellular Matrix Remodeling in Adipose Tissue and Ameliorates Insulin Resistance in Obesity.

    Science.gov (United States)

    Luo, Ting; Nocon, Allison; Fry, Jessica; Sherban, Alex; Rui, Xianliang; Jiang, Bingbing; Xu, X Julia; Han, Jingyan; Yan, Yun; Yang, Qin; Li, Qifu; Zang, Mengwei

    2016-08-01

    Fibrosis is emerging as a hallmark of metabolically dysregulated white adipose tissue (WAT) in obesity. Although adipose tissue fibrosis impairs adipocyte plasticity, little is known about how aberrant extracellular matrix (ECM) remodeling of WAT is initiated during the development of obesity. Here we show that treatment with the antidiabetic drug metformin inhibits excessive ECM deposition in WAT of ob/ob mice and mice with diet-induced obesity, as evidenced by decreased collagen deposition surrounding adipocytes and expression of fibrotic genes including the collagen cross-linking regulator LOX Inhibition of interstitial fibrosis by metformin is likely attributable to the activation of AMPK and the suppression of transforming growth factor-β1 (TGF-β1)/Smad3 signaling, leading to enhanced systemic insulin sensitivity. The ability of metformin to repress TGF-β1-induced fibrogenesis is abolished by the dominant negative AMPK in primary cells from the stromal vascular fraction. TGF-β1-induced insulin resistance is suppressed by AMPK agonists and the constitutively active AMPK in 3T3L1 adipocytes. In omental fat depots of obese humans, interstitial fibrosis is also associated with AMPK inactivation, TGF-β1/Smad3 induction, aberrant ECM production, myofibroblast activation, and adipocyte apoptosis. Collectively, integrated AMPK activation and TGF-β1/Smad3 inhibition may provide a potential therapeutic approach to maintain ECM flexibility and combat chronically uncontrolled adipose tissue expansion in obesity.

  1. Sympathetic activation and endothelial dysfunction in polycystic ovary syndrome are not explained by either obesity or insulin resistance.

    Science.gov (United States)

    Lambert, Elisabeth A; Teede, Helena; Sari, Carolina Ika; Jona, Eveline; Shorakae, Soulmaz; Woodington, Kiri; Hemmes, Robyn; Eikelis, Nina; Straznicky, Nora E; De Courten, Barbora; Dixon, John B; Schlaich, Markus P; Lambert, Gavin W

    2015-12-01

    Polycystic ovary syndrome (PCOS) is a common endocrine condition underpinned by insulin resistance and associated with increased risk of obesity, type 2 diabetes and adverse cardiovascular risk profile. Previous data suggest autonomic imbalance [elevated sympathetic nervous system (SNS) activity and decreased heart rate variability (HRV)] as well as endothelial dysfunction in PCOS. However, it is not clear whether these abnormalities are driven by obesity and metabolic disturbance or whether they are independently related to PCOS. We examined multiunit and single-unit muscle SNS activity (by microneurography), HRV (time and frequency domain analysis) and endothelial function [ischaemic reactive hyperaemia index (RHI) using the EndoPAT device] in 19 overweight/obese women with PCOS (BMI: 31·3 ± 1·5 kg/m(2), age: 31·3 ± 1·6 years) and compared them with 21 control overweight/obese women (BMI: 33·0 ± 1·4 kg/m(2), age: 28·2 ± 1·6 years) presenting a similar metabolic profile (fasting total, HDL and LDL cholesterol, glucose, triglycerides, insulin sensitivity and blood pressure). Women with PCOS had elevated multiunit muscle SNS activity (41 ± 2 vs 33 ± 3 bursts per 100 heartbeats, P obesity and metabolic disturbances. Sympathetic activation and endothelial dysfunction may confer greater cardiovascular risk in women with PCOS. © 2015 John Wiley & Sons Ltd.

  2. Activation of AMP-activated protein kinase signaling pathway by adiponectin and insulin in mouse adipocytes: requirement of acyl-CoA synthetases FATP1 and Acsl1 and association with an elevation in AMP/ATP ratio.

    Science.gov (United States)

    Liu, Qingqing; Gauthier, Marie-Soleil; Sun, Lei; Ruderman, Neil; Lodish, Harvey

    2010-11-01

    Adiponectin activates AMP-activated protein kinase (AMPK) in adipocytes, but the underlying mechanism remains unclear. Here we tested the hypothesis that AMP, generated in activating fatty acids to their CoA derivatives, catalyzed by acyl-CoA synthetases, is involved in AMPK activation by adiponectin. Moreover, in adipocytes, insulin affects the subcellular localization of acyl-CoA synthetase FATP1. Thus, we also tested whether insulin activates AMPK in these cells and, if so, whether it activates through a similar mechanism. We examined these hypotheses by measuring the AMP/ATP ratio and AMPK activation on adiponectin and insulin stimulation and after knocking down acyl-CoA synthetases in adipocytes. We show that adiponectin activation of AMPK is accompanied by an ∼2-fold increase in the cellular AMP/ATP ratio. Moreover, FATP1 and Acsl1, the 2 major acyl-CoA synthetase isoforms in adipocytes, are essential for AMPK activation by adiponectin. We also show that after 40 min. insulin activated AMPK in adipocytes, which was coupled with a 5-fold increase in the cellular AMP/ATP ratio. Knockdown studies show that FATP1 and Acsl1 are required for these processes, as well as for stimulation of long-chain fatty acid uptake by adiponection and insulin. These studies demonstrate that a change in cellular energy state is associated with AMPK activation by both adiponectin and insulin, which requires the activity of FATP1 and Acsl1.

  3. Improved insulin sensitivity after exercise: focus on insulin signaling

    DEFF Research Database (Denmark)

    Frøsig, Christian; Richter, Erik

    2009-01-01

    After a single bout of exercise, the ability of insulin to stimulate glucose uptake is markedly improved locally in the previously active muscles. This makes exercise a potent stimulus counteracting insulin resistance characterizing type 2 diabetes (T2D). It is believed that at least part...... of the mechanism relates to an improved ability of insulin to stimulate translocation of glucose transporters (GLUT4) to the muscle membrane after exercise. How this is accomplished is still unclear; however, an obvious possibility is that exercise interacts with the insulin signaling pathway to GLUT4...... translocation allowing for a more potent insulin response. Parallel to unraveling of the insulin signaling cascade, this has been investigated within the past 25 years. Reviewing existing studies clearly indicates that improved insulin action can occur independent of interactions with proximal insulin signaling...

  4. Insulin Injection

    Science.gov (United States)

    ... or buttocks. Do not inject insulin into muscles, scars, or moles. Use a different site for each ... you are using insulin.Alcohol may cause a decrease in blood sugar. Ask your doctor about the ...

  5. Hypoglycemic activities of lyophilized powder of Gynura divaricata by improving antioxidant potential and insulin signaling in type 2 diabetic mice

    Directory of Open Access Journals (Sweden)

    Bing-Qing Xu

    2015-12-01

    Full Text Available Background: Diabetes mellitus is a serious disease affecting about 5% of people worldwide. Although several studies have indicated hypoglycemic activities of Gynura divaricata (GD, the mechanisms by which GD improves the symptoms of diabetes remain unclear. Objective: The aim of this study was to investigate the potential hypoglycemic effects of GD. Design: The leaves and stems of GD were prepared and lyophilized into a powder, which was added to the diet of mice with type 2 diabetes induced by a high-fat diet in combination with streptozotocin for 4 weeks. During this period, fasting blood glucose (FBG levels and body weight of mice were measured. In addition, at the end of the experiment, a series of assays was performed. Results: GD administration effectively alleviates insulin resistance and induces a decrease in FBG by 59.54% in 1.2% (L GD-treated diabetic group and 56.13% in 4.8% (H GD-treated diabetic group after 4 weeks, respectively, relative to diabetic model mice. The antioxidant capacity was improved by increasing the activities of glutathione peroxidase (GSH-Px and total superoxide dismutase (T-SOD by 64.87% and 53.42% in treatment group H, compared to diabetic model mice, while GD treatment induced a significant decrease in malondialdehyde (MDA level by 50% in treatment group L, compared to the level in diabetic model mice. Furthermore, glucose metabolism was ameliorated by the increased glycogen synthesis in the livers of diabetic mice. In addition, we also demonstrated that the messenger RNA (mRNA and protein expression levels of AKT, PI3K and PDK-1, which are involved in insulin signaling, were significantly increased. Conclusions: Oral administration of the GD-lyophilized powder has been effectively hypoglycemic, which is done by activating insulin signaling and improving antioxidant capacity in mice with type 2 diabetes.

  6. Glycoinsulins: dendritic sialyloligosaccharide-displaying insulins showing a prolonged blood-sugar-lowering activity.

    Science.gov (United States)

    Sato, Masaaki; Furuike, Tetsuya; Sadamoto, Reiko; Fujitani, Naoki; Nakahara, Taku; Niikura, Kenichi; Monde, Kenji; Kondo, Hirosato; Nishimura, Shin-Ichiro

    2004-11-03

    Mono-, di-, and trisialyloligosaccharides were introduced to mutant insulins through enzymatic reactions. Sugar chains were sialylated by alpha2,6-sialyltransferase (alpha2,6-SiaT) via an accessible glutamine residue at the N-terminus of the B-chain attached by transglutaminase (TGase). Sia2,6-di-LacNAc-Ins(B-F1Q) and Sia2,6-tri-LacNAc-Ins(B-F1Q), displaying two and three sialyl-N-acetyllactosamines, respectively, were administered to hyperglycemic mice. Both branched glycoinsulins showed prolonged glucose-lowering effects compared to native or lactose-carrying insulins, showing that sialic acid is important in obtaining a prolonged effect. Sia2,6-tri-LacNAc-Ins(B-F1Q), in particular, induced a significant delay in the recovery of glucose levels.

  7. Polypeptides with nonsuppressible insulin-like and cell-growth promoting activities in human serum: isolation, chemical characterization, and some biological properties of forms I and II.

    Science.gov (United States)

    Rinderknecht, E; Humbel, R E

    1976-07-01

    Serum contains a polypeptide with insulin-like activity not suppressible by insulin antibodies (NSILA). A large-scale isolation procedure for NSILA is described, starting from an acid ethanol extract of a Cohn fraction (precipitate B) obtained from human plasma. Two homogenous polypeptides with insulin-like and cell-growth promoting activities could be isolated by gel filtration, ion exchange chromatography, and preparative polyacrylamide gel electrophoresis. Both components are slightly basic polypeptides with a minimal molecular weight of 5800 +/- 400. Both are single-chain molecules with two intrachain disulfide bridges each and no free sulfhydryl groups. NSILA I and II differ, however, in their amino acid compositions. The N-terminal amino acid sequences are Gly-Pro-Glu- in NSILA I, and Ala-Tyr-Arg- and Tyr-Arg- in NSILA II. Both NSILA I and II enhance net gas exchange in adipose tissue with a specific activity 60 times lower than that of insulin. In the range of 1-50 ng/ml, both substances stimulate [3H]thymidine incorporation into DNA of chick embryo fibroblasts. The same effect can be obtained with insulin but only at concentrations 50-100 times higher than those of NSILA. These results suggest that NSILA I and II are two forms of an insulin-like hormone with predominating effects on cell and tissue growth parameters.

  8. Berberine, a natural plant product, activates AMP-activated protein kinase with beneficial metabolic effects in diabetic and insulin-resistant states.

    Science.gov (United States)

    Lee, Yun S; Kim, Woo S; Kim, Kang H; Yoon, Myung J; Cho, Hye J; Shen, Yun; Ye, Ji-Ming; Lee, Chul H; Oh, Won K; Kim, Chul T; Hohnen-Behrens, Cordula; Gosby, Alison; Kraegen, Edward W; James, David E; Kim, Jae B

    2006-08-01

    Berberine has been shown to have antidiabetic properties, although its mode of action is not known. Here, we have investigated the metabolic effects of berberine in two animal models of insulin resistance and in insulin-responsive cell lines. Berberine reduced body weight and caused a significant improvement in glucose tolerance without altering food intake in db/db mice. Similarly, berberine reduced body weight and plasma triglycerides and improved insulin action in high-fat-fed Wistar rats. Berberine downregulated the expression of genes involved in lipogenesis and upregulated those involved in energy expenditure in adipose tissue and muscle. Berberine treatment resulted in increased AMP-activated protein kinase (AMPK) activity in 3T3-L1 adipocytes and L6 myotubes, increased GLUT4 translocation in L6 cells in a phosphatidylinositol 3' kinase-independent manner, and reduced lipid accumulation in 3T3-L1 adipocytes. These findings suggest that berberine displays beneficial effects in the treatment of diabetes and obesity at least in part via stimulation of AMPK activity.

  9. Effects of AMPK activation on insulin sensitivity and metabolism in leptin-deficient ob/ob mice

    DEFF Research Database (Denmark)

    Zachariah Tom, Robby; Garcia-Roves, Pablo M; Sjögren, Rasmus J O

    2014-01-01

    AMP-activated protein kinase (AMPK) is a heterotrimeric complex, composed of a catalytic subunit (α) and two regulatory subunits (β and γ), which act as a metabolic sensor to regulate glucose and lipid metabolism. A mutation in the γ3 subunit (AMPKγ3(R225Q)) increases basal AMPK phosphorylation......-deficient ob/ob (ob/ob-γ3(R225Q)) mice. Glycogen content was increased, triglyceride content was decreased, and diacylglycerol and ceramide content were unaltered in gastrocnemius muscle from ob/ob-γ3(R225Q) mice, whereas glucose tolerance was unaltered. Insulin-stimulated glucose uptake in extensor digitorum...

  10. Insulin Signalling: The Inside Story.

    Science.gov (United States)

    Posner, Barry I

    2017-02-01

    Insulin signalling begins with binding to its cell surface insulin receptor (IR), which is a tyrosine kinase. The insulin receptor kinase (IRK) is subsequently autophosphorylated and activated to tyrosine phosphorylate key cellular substrates that are essential for entraining the insulin response. Although IRK activation begins at the cell surface, it is maintained and augmented following internalization into the endosomal system (ENS). The peroxovanadium compounds (pVs) were discovered to activate the IRK in the absence of insulin and lead to a full insulin response. Thus, IRK activation is both necessary and sufficient for insulin signalling. Furthermore, this could be shown to occur with activation of only the endosomal IRK. The mechanism of pV action was shown to be the inhibition of IRK-associated phosphotyrosine phosphatases (PTPs). Our studies showed that the duration and intensity of insulin signalling are modulated within ENS by the recruitment of cellular substrates to ENS; intra-endosomal acidification, which promotes dissociation of insulin from the IRK; an endosomal acidic insulinase, which degrades intra-endosomal insulin; and IRK-associated PTPs, which dephosphorylate and, hence, deactivate the IRK. Therefore, the internalization of IRKs is central to insulin signalling and its regulation.

  11. Activity-sensitive signaling by muscle-derived insulin-like growth factors in the developing and regenerating neuromuscular system.

    Science.gov (United States)

    Caroni, P

    1993-08-27

    In the nervous system, activity-sensitive retrograde signaling pathways couple the status of postsynaptic activation to elimination of collaterals during development and collateral sprouting in the adult. This article presents evidence supporting the hypothesis that in the neuromuscular system, skeletal muscle fiber derived insulin-like growth factors play a central role in such signaling. This evidence includes (1) timing and activity-sensitive expression of IGFs in skeletal muscle fibers, (2) identification of an IGF- and activity-sensitive retrograde signaling pathway from developing muscle to motoneurons in the spinal cord, (3) demonstration that IGFs in the muscle are both sufficient and necessary to induce interstitial cell proliferation and intramuscular nerve sprouting in adult muscle.

  12. Identification of plant extracts with potential antidiabetic properties: effect on human peroxisome proliferator-activated receptor (PPAR), adipocyte differentiation and insulin-stimulated glucose uptake.

    Science.gov (United States)

    Christensen, Kathrine B; Minet, Ariane; Svenstrup, Henrik; Grevsen, Kai; Zhang, Hongbin; Schrader, Eva; Rimbach, Gerald; Wein, Silvia; Wolffram, Siegfried; Kristiansen, Karsten; Christensen, Lars P

    2009-09-01

    Thiazolidinediones (TZDs) are insulin sensitizing drugs used to treat type 2 diabetes. The primary target of the TZDs is the peroxisome proliferator-activated receptor (PPAR) gamma, a key regulator of adipogenesis and glucose homeostasis. Currently prescribed TZDs are full PPARgamma agonists, and their use is associated with several side effects. Partial PPARgamma agonists appear to be associated with fewer side effects but may still confer the desired insulin sensitizing action. Extracts from common medicinal/food plants were tested in a screening platform comprising a series of bioassays, including tests for PPARgamma, alpha and delta transactivation, adipocyte differentiation and insulin-stimulated glucose uptake, allowing identification of plants containing potentially interesting PPAR agonists. Twenty-two plant extracts out of 133 were found to increase insulin-stimulated glucose uptake and 18 extracts were found to activate PPARgamma, 3 to activate PPARalpha and gamma, 6 to activate PPARdelta and gamma, and 9 to activate PPARgamma, alpha and delta. Among the 24 different plant species tested in the platform, 50% were shown to contain compounds capable of activating PPARgamma and stimulating insulin-dependent glucose uptake with no or little effect on adipocyte differentiation warranting further studies and characterization.

  13. M19 modulates skeletal muscle differentiation and insulin secretion in pancreatic β-cells through modulation of respiratory chain activity.

    Directory of Open Access Journals (Sweden)

    Linda Cambier

    Full Text Available Mitochondrial dysfunction due to nuclear or mitochondrial DNA alterations contributes to multiple diseases such as metabolic myopathies, neurodegenerative disorders, diabetes and cancer. Nevertheless, to date, only half of the estimated 1,500 mitochondrial proteins has been identified, and the function of most of these proteins remains to be determined. Here, we characterize the function of M19, a novel mitochondrial nucleoid protein, in muscle and pancreatic β-cells. We have identified a 13-long amino acid sequence located at the N-terminus of M19 that targets the protein to mitochondria. Furthermore, using RNA interference and over-expression strategies, we demonstrate that M19 modulates mitochondrial oxygen consumption and ATP production, and could therefore regulate the respiratory chain activity. In an effort to determine whether M19 could play a role in the regulation of various cell activities, we show that this nucleoid protein, probably through its modulation of mitochondrial ATP production, acts on late muscle differentiation in myogenic C2C12 cells, and plays a permissive role on insulin secretion under basal glucose conditions in INS-1 pancreatic β-cells. Our results are therefore establishing a functional link between a mitochondrial nucleoid protein and the modulation of respiratory chain activities leading to the regulation of major cellular processes such as myogenesis and insulin secretion.

  14. Zinc-α2-Glycoprotein Modulates AKT-Dependent Insulin Signaling in Human Adipocytes by Activation of the PP2A Phosphatase.

    Directory of Open Access Journals (Sweden)

    Victòria Ceperuelo-Mallafré

    Full Text Available Evidence from mouse models suggests that zinc-α2-glycoprotein (ZAG is a novel anti-obesity adipokine. In humans, however, data are controversial and its physiological role in adipose tissue (AT remains unknown. Here we explored the molecular mechanisms by which ZAG regulates carbohydrate metabolism in human adipocytes.ZAG action on glucose uptake and insulin action was analyzed. β1 and β2-adrenoreceptor (AR antagonists and siRNA targeting PP2A phosphatase were used to examine the mechanisms by which ZAG modulates insulin sensitivity. Plasma levels of ZAG were measured in a lean patient cohort stratified for HOMA-IR.ZAG treatment increased basal glucose uptake, correlating with an increase in GLUT expression, but induced insulin resistance in adipocytes. Pretreatment of adipocytes with propranolol and a specific β1-AR antagonist demonstrated that ZAG effects on basal glucose uptake and GLUT4 expression are mediated via β1-AR, whereas inhibition of insulin action is dependent on β2-AR activation. ZAG treatment correlated with an increase in PP2A activity. Silencing of the PP2A catalytic subunit abrogated the negative effect of ZAG on insulin-stimulated AKT phosphorylation and glucose uptake but not on GLUT4 expression and basal glucose uptake. ZAG circulating levels were unchanged in a lean patient cohort stratified for HOMA-IR. Neither glucose nor insulin was associated with plasma ZAG.ZAG inhibits insulin-induced glucose uptake in human adipocytes by impairing insulin signaling at the level of AKT in a β2-AR- and PP2A-dependent manner.

  15. Green tea epigallocatechin gallate inhibits insulin stimulation of adipocyte glucose uptake via the 67-kilodalton laminin receptor and AMP-activated protein kinase pathways.

    Science.gov (United States)

    Hsieh, Chi-Fen; Tsuei, Yi-Wei; Liu, Chi-Wei; Kao, Chung-Cheng; Shih, Li-Jane; Ho, Low-Tone; Wu, Liang-Yi; Wu, Chi-Peng; Tsai, Pei-Hua; Chang, Hsin-Huei; Ku, Hui-Chen; Kao, Yung-Hsi

    2010-10-01

    Insulin and (-)-epigallocatechin gallate (EGCG) are reported to regulate obesity and fat accumulation, respectively. This study investigated the pathways involved in EGCG modulation of insulin-stimulated glucose uptake in 3T3-L1 and C3H10T1/2 adipocytes. EGCG inhibited insulin stimulation of adipocyte glucose uptake in a dose- and time-dependent manner. The concentration of EGCG that decreased insulin-stimulated glucose uptake by 50-60% was approximately 5-10 µM for a period of 2 h. At 10 µM, EGCG and gallic acid were more effective than (-)-epicatechin, (-)-epigallocatechin, and (-)-epicatechin 3-gallate. We identified the EGCG receptor [also known as the 67-kDa laminin receptor (67LR)] in fat cells and extended the findings for this study to clarify whether EGCG-induced changes in insulin-stimulated glucose uptake in adipocytes could be mediated through the 67LR. Pretreatment of adipocytes with a 67LR antibody, but not normal rabbit immunoglobulin, prevented the effects of EGCG on insulin-increased glucose uptake. This suggests that the 67LR mediates the effect of EGCG on insulin-stimulated glucose uptake in adipocytes. Moreover, pretreatment with an AMP-activated protein kinase (AMPK) inhibitor, such as compound C, but not with a glutathione (GSH) activator, such as N-acetyl-L-cysteine (NAC), blocked the antiinsulin effect of EGCG on adipocyte glucose uptake. These data suggest that EGCG exerts its anti-insulin action on adipocyte glucose uptake via the AMPK, but not the GSH, pathway. The results of this study possibly support that EGCG mediates fat content. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Mulberry (Morus alba L.) Fruit Extract Containing Anthocyanins Improves Glycemic Control and Insulin Sensitivity via Activation of AMP-Activated Protein Kinase in Diabetic C57BL/Ksj-db/db Mice.

    Science.gov (United States)

    Choi, Kyung Ha; Lee, Hyun Ah; Park, Mi Hwa; Han, Ji-Sook

    2016-08-01

    The effect of mulberry (Morus alba L.) fruit extract (MFE) on hyperglycemia and insulin sensitivity in an animal model of type 2 diabetes was evaluated. C57BL/Ksj-diabetic db/db mice were divided into three groups: diabetic control, rosiglitazone, and MFE groups. Blood glucose, plasma insulin, and intraperitoneal glucose were measured, and an insulin tolerance test was performed after MFE supplementation in db/db mice. In addition, the protein levels of various targets of insulin signaling were measured by western blotting. The blood levels of glucose and HbA1c were significantly lower in the MFE-supplemented group than in the diabetic control group. Moreover, glucose and insulin tolerance tests showed that MFE treatment increased insulin sensitivity. The homeostatic index of insulin resistance significantly decreased in the MFE-supplemented group relative to the diabetic control group. MFE supplementation significantly stimulated the levels of phosphorylated (p)-AMP-activated protein kinase (pAMPK) and p-Akt substrate of 160 kDa (pAS160) and enhanced the level of plasma membrane-glucose transporter 4 (GLUT4) in skeletal muscles. Further, dietary MFE significantly increased pAMPK and decreased the levels of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase in the liver. MFE may improve hyperglycemia and insulin sensitivity via activation of AMPK and AS160 in skeletal muscles and inhibition of gluconeogenesis in the liver.

  17. Impaired activity and gene expression of hexokinase II in muscle from non-insulin-dependent diabetes mellitus patients

    DEFF Research Database (Denmark)

    Vestergaard, H; Bjørbaek, C; Hansen, T

    1995-01-01

    -phosphate concentrations in muscle have been found in non-insulin-dependent diabetes mellitus (NIDDM) patients when examined during a hyperglycemic hyperinsulinemic clamp. These findings [correction of finding] are consistent with a defect in glucose transport and/or phosphorylation. In the present study...... +/- 5% in controls (P = 0.08) of total muscle HK activity when measured at a glucose media of 0.11 mmol/liter and 31 +/- 4 and 47 +/- 7% (P = 0.02) when measured at 0.11 mmol/liter of glucose. HKII mRNA, HKII immunoreactive protein level, and HKII activity were significantly decreased in NIDDM patients...... with fasting plasma glucose concentrations (r = -0.45, P = 0.004; r = -0.54, P concentrations (r = -0.46, P = 0.003; r = -0.37, P = 0.02, respectively). In conclusion, NIDDM patients are characterized by a reduced activity and a reduced gene...

  18. Dexamethasone effects on creatine kinase activity and insulin-like growth factor receptors in cultured muscle cells

    Science.gov (United States)

    Whitson, Peggy A.; Stuart, Charles A.; Huls, M. H.; Sams, Clarence F.; Cintron, Nitza M.

    1989-01-01

    The effect of dexamethasone on the activity of creatine kinase (CK) and the insulin-like growth factor I (IGF-I) binding were investigated using skeletal- and cardiac-muscle-derived cultured cell lines (mouse, C2C12; rat, L6 and H9c2). It was found that, in skeletal muscle cells, dexamethasone treatment during differentiation of skeletal-muscle cells caused dose-dependent increases in CK activity and increases in the degree of myotube formation, whereas cardiac cells (H9c2) exhibited very low CK activity during culture or dexamethasone treatment. Results for IGF-I binding were similar in all three cell lines. The IGF-I binding to dexamethasone-treated cells (50 nM for 24 hr on the day prior to confluence) resulted in an increased number of available binding sites, with no effect on the binding affinities.

  19. Dexamethasone effects on creatine kinase activity and insulin-like growth factor receptors in cultured muscle cells

    Science.gov (United States)

    Whitson, Peggy A.; Stuart, Charles A.; Huls, M. H.; Sams, Clarence F.; Cintron, Nitza M.

    1989-01-01

    The effect of dexamethasone on the activity of creatine kinase (CK) and the insulin-like growth factor I (IGF-I) binding were investigated using skeletal- and cardiac-muscle-derived cultured cell lines (mouse, C2C12; rat, L6 and H9c2). It was found that, in skeletal muscle cells, dexamethasone treatment during differentiation of skeletal-muscle cells caused dose-dependent increases in CK activity and increases in the degree of myotube formation, whereas cardiac cells (H9c2) exhibited very low CK activity during culture or dexamethasone treatment. Results for IGF-I binding were similar in all three cell lines. The IGF-I binding to dexamethasone-treated cells (50 nM for 24 hr on the day prior to confluence) resulted in an increased number of available binding sites, with no effect on the binding affinities.

  20. Antihyperglycemic Activity of Eucalyptus tereticornis in Insulin-Resistant Cells and a Nutritional Model of Diabetic Mice

    Science.gov (United States)

    Guillén, Alis; Granados, Sergio; Rivas, Kevin Eduardo; Estrada, Omar; Echeverri, Luis Fernando; Balcázar, Norman

    2015-01-01

    Eucalyptus tereticornis is a plant used in traditional medicine to control diabetes, but this effect has not been proved scientifically. Here, we demonstrated through in vitro assays that E. tereticornis extracts increase glucose uptake and inhibit their production in insulin-resistant C2C12 and HepG2 cells, respectively. Furthermore, in a nutritional model using diabetic mice, the administration of ethyl acetate extract of E. tereticornis reduced fasting glycaemia, improved tolerance to glucose, and reduced resistance to insulin. Likewise, this extract had anti-inflammatory effects in adipose tissue when compared to control diabetic mice. Via bioguided assays and sequential purification of the crude extract, a triterpenoid-rich fraction from ethyl acetate extracts was shown to be responsible for the biological activity. Similarly, we identified the main compound responsible for the antihyperglycemic activity in this extract. This study shows that triterpenes found in E. tereticornis extracts act as hypoglycemic/antidiabetic compounds and contribute to the understanding of their use in traditional medicine. PMID:26366171

  1. The adipose renin-angiotensin system modulates sysemic markers of insulin sensitivity activates the intrarenal renin-angiotensin system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suyeon [University of Tennessee, Knoxville (UTK); Soltani-Bejnood, Morvarid [University of Tennessee, Knoxville (UTK); Quignard-Boulange, Annie [Centre Biomedical des Cordeliers, Paris, France; Massiera, Florence [Centre de Biochimie, Nice, France; Teboul, Michele [Centre de Biochimie, Nice, France; Ailhaud, Gerard [Centre de Biochimie, Nice, France; Kim, Jung [University of Tennessee, Knoxville (UTK); Moustaid-Moussa, Naima [University of Tennessee, Knoxville (UTK); Voy, Brynn H [ORNL

    2006-07-01

    BACKGROUND: A growing body of data provides increasing evidence that the adipose tissue renin-angiotensin system (RAS) contributes to regulation of fat mass. Beyond its paracrine actions within adipose tissue, adipocyte-derived angiotensin II (Ang II) may also impact systemic functions such as blood pressure and metabolism. METHODS AND RESULTS: We used a genetic approach to manipulate adipose RAS activity in mice and then study the consequences on metabolic parameters and on feedback regulation of the RAS. The models included deletion of the angiotensinogen (Agt) gene (Agt-KO), its expression solely in adipose tissue under the control of an adipocyte-specific promoter (aP2-Agt/ Agt-KO), and overexpression in adipose tissue of wild type mice (aP2-Agt). Total body weight, epididymal fat pad weight, and circulating levels of leptin, insulin and resistin were significantly decreased in Agt-KO mice, while plasma adiponectin levels were increased. Overexpression of Agt in adipose tissue resulted in increased adiposity and plasma leptin and insulin levels compared to wild type (WT) controls. Angiotensinogen and type I Ang II receptor protein levels were also markedly elevated in kidney of aP2-Agt mice, suggesting that hypertension in these animals may be in part due to stimulation of the intrarenal RAS. CONCLUSIONS: Taken together, the results from this study demonstrate that alterations in adipose RAS activity significantly alter both local and systemic physiology in a way that may contribute to the detrimental health effects of obesity.

  2. Antihyperglycemic Activity of Eucalyptus tereticornis in Insulin-Resistant Cells and a Nutritional Model of Diabetic Mice

    Directory of Open Access Journals (Sweden)

    Alis Guillén

    2015-01-01

    Full Text Available Eucalyptus tereticornis is a plant used in traditional medicine to control diabetes, but this effect has not been proved scientifically. Here, we demonstrated through in vitro assays that E. tereticornis extracts increase glucose uptake and inhibit their production in insulin-resistant C2C12 and HepG2 cells, respectively. Furthermore, in a nutritional model using diabetic mice, the administration of ethyl acetate extract of E. tereticornis reduced fasting glycaemia, improved tolerance to glucose, and reduced resistance to insulin. Likewise, this extract had anti-inflammatory effects in adipose tissue when compared to control diabetic mice. Via bioguided assays and sequential purification of the crude extract, a triterpenoid-rich fraction from ethyl acetate extracts was shown to be responsible for the biological activity. Similarly, we identified the main compound responsible for the antihyperglycemic activity in this extract. This study shows that triterpenes found in E. tereticornis extracts act as hypoglycemic/antidiabetic compounds and contribute to the understanding of their use in traditional medicine.

  3. Torque and Muscle Activation Impairment Along With Insulin Resistance Are Associated With Falls in Women With Fibromyalgia.

    Science.gov (United States)

    Góes, Suelen M; Stefanello, Joice M F; Homann, Diogo; Lodovico, Angélica; Hubley-Kozey, Cheryl L; Rodacki, André L F

    2016-11-01

    Góes, SM, Stefanello, JMF, Homann, D, Lodovico, A, Hubley-Kozey, CL, and Rodacki, ALF. Torque and muscle activation impairment along with insulin resistance are associated with falls in women with fibromyalgia. J Strength Cond Res 30(11): 3155-3164, 2016-Fibromyalgia (FM) is a chronic pain condition associated with reduced muscle strength, which can lead to functional incapacity and higher risk of falls. The purpose of the study was to compare maximal ankle joint torque, muscle activation, and metabolic changes between women with and without FM. In addition, the relationship between those aspects and retrospectively reported falls in women with FM was determined. Twenty-nine middle-aged women with FM and 30 controls were recruited. Fall history, pain intensity, and pain threshold were assessed. Plasma glucose levels and insulin resistance (IR) were determined. Peak torque and rate of torque development (RTD) were calculated, and muscle activation was assessed from maximum isometric voluntary ankle dorsiflexion and plantar flexion contractions. In addition, voluntary muscle activation failure of the anterior tibialis muscle during maximal dorsiflexion was calculated. When compared to controls, women with FM reported higher number of retrospectively reported falls, exhibited higher IR, showed reduced plantar flexion and dorsiflexion RTD, had lower plantar flexion peak torque, and demonstrated more antagonist coactivation and higher muscle activation failure (p ≤ 0.05). Higher muscle activation failure was explained by glucose level and pain intensity (adj R = 0.28; p ≤ 0.05). Reduced plantar flexion and dorsiflexion peak torque explained 80% of retrospectively reported falls variance; also, high antagonist coactivation (odds ratio [OR] = 1.6; p ≤ 0.05) and high IR (OR = 1.8; p ≤ 0.05) increased the chance of falls in the FM group. A combination of metabolic factors and muscle function increased the odds of retrospectively reporting a fall in FM. Both aspects

  4. Epinephrine-stimulated glycogen breakdown activates glycogen synthase and increases insulin-stimulated glucose uptake in epitrochlearis muscles.

    Science.gov (United States)

    Kolnes, Anders J; Birk, Jesper B; Eilertsen, Einar; Stuenæs, Jorid T; Wojtaszewski, Jørgen F P; Jensen, Jørgen

    2015-02-01

    Epinephrine increases glycogen synthase (GS) phosphorylation and decreases GS activity but also stimulates glycogen breakdown, and low glycogen content normally activates GS. To test the hypothesis that glycogen content directly regulates GS phosphorylation, glycogen breakdown was stimulated in condition with decreased GS activation. Saline or epinephrine (0.02 mg/100 g rat) was injected subcutaneously in Wistar rats (∼130 g) with low (24-h-fasted), normal (normal diet), and high glycogen content (fasted-refed), and epitrochlearis muscles were removed after 3 h and incubated ex vivo, eliminating epinephrine action. Epinephrine injection reduced glycogen content in epitrochlearis muscles with high (120.7 ± 17.8 vs. 204.6 ± 14.5 mmol/kg, P < 0.01) and normal glycogen (89.5 ± 7.6 vs. 152 ± 8.1 mmol/kg, P < 0.01), but not significantly in muscles with low glycogen (90.0 ± 5.0 vs. 102.8 ± 7.8 mmol/kg, P = 0.17). In saline-injected rats, GS phosphorylation at sites 2+2a, 3a+3b, and 1b was higher and GS activity lower in muscles with high compared with low glycogen. GS sites 2+2a and 3a+3b phosphorylation decreased and GS activity increased in muscles where epinephrine decreased glycogen content; these parameters were unchanged in epitrochlearis from fasted rats where epinephrine injection did not decrease glycogen content. Incubation with insulin decreased GS site 3a+3b phosphorylation independently of glycogen content. Insulin-stimulated glucose uptake was increased in muscles where epinephrine injection decreased glycogen content. In conclusion, epinephrine stimulates glycogenolysis in epitrochlearis muscles with normal and high, but not low, glycogen content. Epinephrine-stimulated glycogenolysis decreased GS phosphorylation and increased GS activity. These data for the first time document direct regulation of GS phosphorylation by glycogen content. Copyright © 2015 the American Physiological Society.

  5. ANP system activity predicts variability of fat mass reduction and insulin sensitivity during weight loss.

    Science.gov (United States)

    Brachs, Maria; Wiegand, Susanna; Leupelt, Verena; Ernert, Andrea; Kintscher, Ulrich; Jumpertz von Schwarzenberg, Reiner; Decker, Anne-Marie; Bobbert, Thomas; Hübner, Norbert; Chen, Wei; Krude, Heiko; Spranger, Joachim; Mai, Knut

    2016-06-01

    In weight loss trials, a considerable inter-individual variability in reduction of fat mass and changes of insulin resistance is observed, even under standardized study conditions. The underlying mechanisms are not well understood. Given the metabolic properties of the atrial natriuretic peptide (ANP) system, we hypothesized that ANP signaling might be involved in this phenomenon by changes of ANP secretion or receptor balance. Therefore, we investigated the impact of systemic, adipose and myocellular ANP system on metabolic and anthropometric improvements during weight loss. We comprehensively investigated 143 subjects (31 male, 112 female) before and after a 3 month-standardized weight loss program. The time course of BMI, fat mass, insulin sensitivity, circulating mid-regional proANP (MR-proANP) levels as well as adipose and myocellular natriuretic receptor A (NPR-A) and C (NPR-C) mRNA expression were investigated. BMI decreased by -12.6±3.7%. This was accompanied by a remarkable decrease of adipose NPR-C expression (1005.0±488.4 vs. 556.7±465.6; ploss induced changes in NPR-C (ΔNPR-C) was linked to relative reduction of total fat mass (ΔFM) (r=0.281; ploss induced ΔNPR-C independently explained 22.7% of ΔFM. In addition, ΔMR-proANP was independently associated with improvement of insulin sensitivity (standardized ß=0.246, ploss induced fat mass reduction. Our comprehensive human data support that peripheral ANP signalling is involved in control of adipose tissue plasticity and function during weight loss. (Funded by the Deutsche Forschungsgemeinschaft (KFO281/2), the Berlin Institute of Health (BIH) and the German Centre for Cardiovascular Research (DZHK/BMBF); ClinicalTrials.gov number: NCT00850629). Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Targeting AMP-activated protein kinase in adipocytes to modulate obesity-related adipokine production associated with insulin resistance and breast cancer cell proliferation

    Directory of Open Access Journals (Sweden)

    Grisouard Jean

    2011-07-01

    Full Text Available Abstract Background Adipokines, e.g. TNFα, IL-6 and leptin increase insulin resistance, and consequent hyperinsulinaemia influences breast cancer progression. Beside its mitogenic effects, insulin may influence adipokine production from adipocyte stromal cells and paracrine enhancement of breast cancer cell growth. In contrast, adiponectin, another adipokine is protective against breast cancer cell proliferation and insulin resistance. AMP-activated protein kinase (AMPK activity has been found decreased in visceral adipose tissue of insulin-resistant patients. Lipopolysaccharides (LPS link systemic inflammation to high fat diet-induced insulin resistance. Modulation of LPS-induced adipokine production by metformin and AMPK activation might represent an alternative way to treat both, insulin resistance and breast cancer. Methods Human preadipocytes obtained from surgical biopsies were expanded and differentiated in vitro into adipocytes, and incubated with siRNA targeting AMPKalpha1 (72 h, LPS (24 h, 100 μg/ml and/or metformin (24 h, 1 mM followed by mRNA extraction and analyses. Additionally, the supernatant of preadipocytes or derived-adipocytes in culture for 24 h was used as conditioned media to evaluate MCF-7 breast cancer cell proliferation. Results Conditioned media from preadipocyte-derived adipocytes, but not from undifferentiated preadipocytes, increased MCF-7 cell proliferation (p Conclusions Adipocyte-secreted factors enhance breast cancer cell proliferation, while AMPK and metformin improve the LPS-induced adipokine imbalance. Possibly, AMPK activation may provide a new way not only to improve the obesity-related adipokine profile and insulin resistance, but also to prevent obesity-related breast cancer development and progression.

  7. Regulation of gene expression by glucose in pancreatic beta -cells (MIN6) via insulin secretion and activation of phosphatidylinositol 3'-kinase.

    Science.gov (United States)

    da Silva Xavier, G; Varadi, A; Ainscow, E K; Rutter, G A

    2000-11-17

    Increases in glucose concentration control the transcription of the preproinsulin (PPI) gene and several other genes in the pancreatic islet beta-cell. Although recent data have demonstrated that secreted insulin may regulate the PPI gene (Leibiger, I. B., Leibiger, B., Moede, T., and Berggren, P. O. (1998) Mol. Cell 1, 933-938), the role of insulin in the control of other beta-cell genes is unexplored. To study the importance of insulin secretion in the regulation of the PPI and liver-type pyruvate kinase (L-PK) genes by glucose, we have used intranuclear microinjection of promoter-luciferase constructs into MIN6 beta-cells and photon-counting imaging. The activity of each promoter was increased either by 30 (versus 3) mm glucose or by 1-20 nm insulin. These effects of insulin were not due to enhanced glucose metabolism since culture with the hormone had no impact on the stimulation of increases in intracellular ATP concentration caused by 30 mm glucose. Furthermore, the islet-specific glucokinase promoter and cellular glucokinase immunoreactivity were unaffected by 30 mm glucose or 20 nm insulin. Inhibition of insulin secretion with the Ca(2+) channel blocker verapamil, the ATP-sensitive K(+) channel opener diazoxide, or the alpha(2)-adrenergic agonist clonidine blocked the effects of glucose on L-PK gene transcription. Similarly, 30 mm glucose failed to induce the promoter after inhibition of phosphatidylinositol 3'-kinase activity with LY294002 and the expression of dominant negative-acting phosphatidylinositol 3'-kinase (Deltap85) or the phosphoinositide 3'-phosphatase PTEN (phosphatase and tensin homologue). LY294002 also diminished the activation of the L-PK gene caused by inhibition of 5'-AMP-activated protein kinase with anti-5'-AMP-activated protein kinase alpha2 antibodies. Conversely, stimulation of insulin secretion with 13 mm KCl or 10 microm tolbutamide strongly activated the PPI and L-PK promoters. These data indicate that, in MIN6 beta

  8. Insulin-induced Stimulation of Na+,K+-ATPase Activity in Kidney Proximal Tubule Cells Depends on Phosphorylation of the α-Subunit at Tyr-10

    Science.gov (United States)

    Féraille, Eric; Carranza, Maria Luisa; Gonin, Sandrine; Béguin, Pascal; Pedemonte, Carlos; Rousselot, Martine; Caverzasio, Joseph; Geering, Käthi; Martin, Pierre-Yves; Favre, Hervé

    1999-01-01

    Phosphorylation of the α-subunit of Na+,K+-ATPase plays an important role in the regulation of this pump. Recent studies suggest that insulin, known to increase solute and fluid reabsorption in mammalian proximal convoluted tubule (PCT), is stimulating Na+,K+-ATPase activity through the tyrosine phosphorylation process. This study was therefore undertaken to evaluate the role of tyrosine phosphorylation of the Na+,K+-ATPase α-subunit in the action of insulin. In rat PCT, insulin and orthovanadate (a tyrosine phosphatase inhibitor) increased tyrosine phosphorylation level of the α-subunit more than twofold. Their effects were not additive, suggesting a common mechanism of action. Insulin-induced tyrosine phosphorylation was prevented by genistein, a tyrosine kinase inhibitor. The site of tyrosine phosphorylation was identified on Tyr-10 by controlled trypsinolysis in rat PCTs and by site-directed mutagenesis in opossum kidney cells transfected with rat α-subunit. The functional relevance of Tyr-10 phosphorylation was assessed by 1) the abolition of insulin-induced stimulation of the ouabain-sensitive 86Rb uptake in opossum kidney cells expressing mutant rat α1-subunits wherein tyrosine was replaced by alanine or glutamine; and 2) the similarity of the time course and dose dependency of the insulin-induced increase in ouabain-sensitive 86Rb uptake and tyrosine phosphorylation. These findings indicate that phosphorylation of the Na+,K+-ATPase α-subunit at Tyr-10 likely participates in the physiological control of sodium reabsorption in PCT. PMID:10473631

  9. Low-Frequency Electroacupuncture Improves Insulin Sensitivity in Obese Diabetic Mice through Activation of SIRT1/PGC-1α in Skeletal Muscle

    Directory of Open Access Journals (Sweden)

    Fengxia Liang

    2011-01-01

    Full Text Available Electroacupuncture (EA has been observed to reduce insulin resistance in obesity and diabetes. However, the biochemical mechanism underlying this effect remains unclear. This study investigated the effects of low-frequency EA on metabolic action in genetically obese and type 2 diabetic db/db mice. Nine-week-old db/m and db/db mice were randomly divided into four groups, namely, db/m, db/m + EA, db/db, and db/db + EA. db/m + EA and db/db + EA mice received 3-Hz electroacupuncture five times weekly for eight consecutive weeks. In db/db mice, EA tempered the increase in fasting blood glucose, food intake, and body mass and maintained insulin levels. In EA-treated db/db mice, improved insulin sensitivity was established through intraperitoneal insulin tolerance test. EA was likewise observed to decrease free fatty acid levels in db/db mice; it increased protein expression in skeletal muscle Sirtuin 1 (SIRT1 and induced gene expression of peroxisome proliferator-activated receptor coactivator (PGC-, nuclear respiratory factor 1 (NRF1, and acyl-CoA oxidase (ACOX. These results indicated that EA offers a beneficial effect on insulin resistance in obese and diabetic db/db mice, at least partly, via stimulation of SIRT1/PGC-, thus resulting in improved insulin signal.

  10. Paternal Insulin-like Growth Factor 2 (Igf2 Regulates Stem Cell Activity During Adulthood

    Directory of Open Access Journals (Sweden)

    Vilma Barroca

    2017-02-01

    Full Text Available Insulin-like Growth Factor 2 (IGF2 belongs to the IGF/Insulin pathway, a highly conserved evolutionarily network that regulates growth, aging and lifespan. Igf2 is highly expressed in the embryo and in cancer cells. During mouse development, Igf2 is expressed in all sites where hematopoietic stem cells (HSC successively expand, then its expression drops at weaning and becomes undetectable when adult HSC have reached their niches in bones and start to self-renew. In the present study, we aim to discover the role of IGF2 during adulthood. We show that Igf2 is specifically expressed in adult HSC and we analyze HSC from adult mice deficient in Igf2 transcripts. We demonstrate that Igf2 deficiency avoids the age-related attrition of the HSC pool and that Igf2 is necessary for tissue homeostasis and regeneration. Our study reveals that the expression level of Igf2 is critical to maintain the balance between stem cell self-renewal and differentiation, presumably by regulating the interaction between HSC and their niche. Our data have major clinical interest for transplantation: understanding the changes in adult stem cells and their environments will improve the efficacy of regenerative medicine and impact health- and life-span.

  11. Signaling of the p21-activated kinase (PAK1) coordinates insulin-stimulated actin remodeling and glucose uptake in skeletal muscle cells.

    Science.gov (United States)

    Tunduguru, Ragadeepthi; Chiu, Tim T; Ramalingam, Latha; Elmendorf, Jeffrey S; Klip, Amira; Thurmond, Debbie C

    2014-11-15

    Skeletal muscle accounts for ∼ 80% of postprandial glucose clearance, and skeletal muscle glucose clearance is crucial for maintaining insulin sensitivity and euglycemia. Insulin-stimulated glucose clearance/uptake entails recruitment of glucose transporter 4 (GLUT4) to the plasma membrane (PM) in a process that requires cortical F-actin remodeling; this process is dysregulated in Type 2 Diabetes. Recent studies have implicated PAK1 as a required element in GLUT4 recruitment in mouse skeletal muscle in vivo, although its underlying mechanism of action and requirement in glucose uptake remains undetermined. Toward this, we have employed the PAK1 inhibitor, IPA3, in studies using L6-GLUT4-myc muscle cells. IPA3 fully ablated insulin-stimulated GLUT4 translocation to the PM, corroborating the observation of ablated insulin-stimulated GLUT4 accumulation in the PM of skeletal muscle from PAK1(-/-) knockout mice. IPA3-treatment also abolished insulin-stimulated glucose uptake into skeletal myotubes. Mechanistically, live-cell imaging of myoblasts expressing the F-actin biosensor LifeAct-GFP treated with IPA3 showed blunting of the normal insulin-induced cortical actin remodeling. This blunting was underpinned by a loss of normal insulin-stimulated cofilin dephosphorylation in IPA3-treated myoblasts. These findings expand upon the existing model of actin remodeling in glucose uptake, by placing insulin-stimulated PAK1 signaling as a required upstream step to facilitate actin remodeling and subsequent cofilin dephosphorylation. Active, dephosphorylated cofilin then provides the G-actin substrate for continued F-actin remodeling to facilitate GLUT4 vesicle translocation for glucose uptake into the skeletal muscle cell.

  12. Insulin allergy.

    Science.gov (United States)

    Ghazavi, Mohammad K; Johnston, Graham A

    2011-01-01

    Insulin reactions occur rarely but are of tremendous clinical importance. The first was reported in 1922 as a callus reaction at the injection site of insufficiently purified bovine insulin. Porcine insulin was subsequently found to be less allergenic than bovine insulin. Increasingly pure insulins have decreased the risk of adverse reactions, and the production of recombinant insulin with the same amino sequence as human insulin saw a large decrease in adverse reactions. Currently, the prevalence of allergic reactions to insulin products appears to be approximately 2%, and less than one-third of these events have been considered related to the insulin itself. Other reactions occur due to the preservatives added to insulin, including zinc, protamine, and meta-cresol. Allergic reactions can be type I or immunoglobulin E-mediated, type III or Arthus, and type IV or delayed-type hypersensitivity reactions. Type I reactions are the most common and can, rarely, cause anaphylaxis. In contrast, type IV reactions can occur after a delay of several days. Investigations include skin prick testing, patch testing, intradermal testing, and occasionally, skin biopsy.

  13. Biosimilar insulins.

    Science.gov (United States)

    Heinemann, Lutz

    2012-08-01

    Until now most insulin used in developed countries is manufactured and distributed by a small number of multinational companies. Other pharmaceutical companies - many of these are located in countries such as India or China - are also able to manufacture insulin with modern biotechnological methods. Additionally, the patents for many insulin formulations have expired or are going to expire soon. This enables such companies to produce insulins and to apply for market approval of these as biosimilar insulins (BIs) in highly regulated markets such as the EU or the US. To understand the complexity of BIs' approval and usage, scientific and regulatory aspects have to be discussed. Differences in the manufacturing process (none of the insulin-manufacturing procedures are identical) result in the fact that all insulin that might become BIs differ from the originator insulin to some extent. The question is, have such differences in the structure of the insulin molecule and or the purity and so on clinically relevant consequences for the biological effects induced or not. The guidelines already in place in the EU for market approval require that the manufacturer demonstrates that his insulin has a safety and efficacy profile that is similar to that of the 'original' insulin formulation. Recently guidelines for biosimilars were issued in the US; however, these do not cover insulin. Although a challenging approval process for insulins to become BI might be regarded as a hurdle to keep companies out of certain markets, it is fair to say that the potential safety and efficacy issues surrounding BI are substantial and relevant, and do warrant a careful and evidence-driven approval process. Nevertheless, it is very likely that in the next years, BIs will come to the market also in highly regulated markets.

  14. Sustained Action of Ceramide on the Insulin Signaling Pathway in Muscle Cells: IMPLICATION OF THE DOUBLE-STRANDED RNA-ACTIVATED PROTEIN KINASE.

    Science.gov (United States)

    Hage Hassan, Rima; Pacheco de Sousa, Ana Catarina; Mahfouz, Rana; Hainault, Isabelle; Blachnio-Zabielska, Agnieszka; Bourron, Olivier; Koskas, Fabien; Górski, Jan; Ferré, Pascal; Foufelle, Fabienne; Hajduch, Eric

    2016-02-01

    In vivo, ectopic accumulation of fatty acids in muscles leads to alterations in insulin signaling at both the IRS1 and Akt steps. However, in vitro treatments with saturated fatty acids or their derivative ceramide demonstrate an effect only at the Akt step. In this study, we adapted our experimental procedures to mimic the in vivo situation and show that the double-stranded RNA-dependent protein kinase (PKR) is involved in the long-term effects of saturated fatty acids on IRS1. C2C12 or human muscle cells were incubated with palmitate or directly with ceramide for short or long periods, and insulin signaling pathway activity was evaluated. PKR involvement was assessed through pharmacological and genetic studies. Short-term treatments of myotubes with palmitate, a ceramide precursor, or directly with ceramide induce an inhibition of Akt, whereas prolonged periods of treatment show an additive inhibition of insulin signaling through increased IRS1 serine 307 phosphorylation. PKR mRNA, protein, and phosphorylation are increased in insulin-resistant muscles. When PKR activity is reduced (siRNA or a pharmacological inhibitor), serine phosphorylation of IRS1 is reduced, and insulin-induced phosphorylation of Akt is improved. Finally, we show that JNK mediates ceramide-activated PKR inhibitory action on IRS1. Together, in the long term, our results show that ceramide acts at two distinct levels of the insulin signaling pathway (IRS1 and Akt). PKR, which is induced by both inflammation signals and ceramide, could play a major role in the development of insulin resistance in muscle cells.

  15. Effects of acute pinitol supplementation on plasma pinitol concentration, whole body glucose tolerance, and activation of the skeletal muscle insulin receptor in older humans.

    Science.gov (United States)

    Stull, A J; Wood, K V; Thyfault, J P; Campbell, W W

    2009-05-01

    Limited research with rodents and humans suggests that oral ingestion of pinitol (3- O-methyl- D- CHIRO-inositol) might positively influence glucose tolerance. This double-blinded, placebo-controlled, and cross-over study assessed the effects of acute pinitol supplementation on plasma pinitol concentration, glucose tolerance, insulin sensitivity, and activation of the skeletal muscle insulin receptor. Fifteen older, nondiabetic subjects (62+/-1 years, mean+/-SEM) completed four, 1-day trials. Subjects consumed a non-nutritive beverage with nothing (placebo) or 1,000 mg pinitol. Sixty minutes later, the subjects consumed beverages that were either energy- and carbohydrate-free (Sham) or contained 75 g glucose (OGTT). Blood samples were collected frequently over the 240-min testing period. For the OGTT trials only, vastus lateralis samples were obtained before the placebo and pinitol supplementation and 60 min after consuming the 75 g glucose beverage. Plasma pinitol concentration increased and was maintained for 240 min. Pinitol did not influence the fasting state and 180-min area under the curves for plasma glucose and insulin during the Sham and OGTT trials or hepatic (placebo 0.83+/-0.08; pinitol 0.80+/-0.08) and whole-body (placebo 6.10+/-0.54; pinitol 6.22+/-0.52) insulin sensitivities. Activation of the muscle insulin receptor was increased by 140% with glucose ingestion (Pre 0.62+/-0.12; Post 1.49+/-0.35), but pinitol did not influence this response. These results show that the pinitol supplement was quickly absorbed, but did not acutely influence indices of whole-body glucose tolerance and insulin sensitivity, or the activation of the skeletal muscle insulin receptor in older, nondiabetic humans.

  16. The effects of physical activity and fitness in adolescence on cognition in adulthood and the role of insulin-like growth factor I

    NARCIS (Netherlands)

    Ferro, D.A.; Deijen, J.B.; Koppes, L.L.; Mechelen, W. van; Twisk, J.W.; Drent, M.L.

    2016-01-01

    Background: Physical activity and fitness in adolescence may improve cognition in adulthood by increasing insulin-like growth factor I (IGF-I). Methods: As part of the Amsterdam Growth and Health Longitudinal Study, following subjects from age 13 to 42 years, physical activity and fitness of 303

  17. Effect of insulin and metformin on methylation and glycolipid metabolism of peroxisome proliferator-activated receptor γcoactivator-1A of rat offspring with gestational diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Ai-Qin Song; Li-Rong Sun; Yan-Xia Zhao; Yan-Hua Gao; Lei Chen

    2016-01-01

    Objective: To discuss the effect of insulin and metformin on amethylation and glycolipid metabolism of peroxisome proliferator-activated receptor γ coactivator-1A (PPARGC1A) ofrat offspring with gestational diabetes mellitus (GDM). Methods: A total of 45 pregnant rats received the intraperitoneal injection of streptozotocin to establish the pregnant rat model of GDM. A total of 21 pregnant rats with GDM were randomly divided into three groups, with 7 rats in each group, namely the insulin group, metformin group and control group. Rats in the insulin group received the abdominal subcutaneous injection of 1 mL/kg recombinant insulin glargine at 18: 00 every day. Rats in the metformin group received the intragastric infusion of metformin hydrochloride at 18: 00 every day, with the first dose of 300 mg/kg. The doses of two groups were adjusted every 3 d to maintain the blood glucose level at 2.65-7.62 mmol/L. Rats in the control group received the intragastric infusion of 1 mL normal saline at 18:00 every day. After the natural delivery of pregnant rats, 10 offspring rats were randomly selected from each group. At birth, 4 wk and 8 wk after the birth of offspring rats, the weight of offspring rats was measured. The blood glucose level of offspring rats was measured at 4 wk and 8 wk, while the level of serum insulin, triglyceride and leptin was measured at 8 wk.Results: The weight of offspring rats at birth in the insulin group and metformin group was significantly lower than the one in the control group (P0.05). The fasting blood glucose and random blood glucose in the insulin group and metformin group at 4 wk and 8 wk were all significantly lower than ones in the control group (P0.05). The expression of PPARGC1A mRNA in the insulin group and metformin group was significantly higher and the methylation level of PPARGC1A was significantly lower than the one in the control group (P0.05). Insulin and leptin at 8 wk in the insulin group and metformin group were

  18. Chronic unpredictable stress exacerbates lipopolysaccharide-induced activation of nuclear factor-kappaB in the frontal cortex and hippocampus via glucocorticoid secretion.

    Science.gov (United States)

    Munhoz, Carolina Demarchi; Lepsch, Lucilia B; Kawamoto, Elisa Mitiko; Malta, Marília Brinati; Lima, Larissa de Sá; Avellar, Maria Christina Werneck; Sapolsky, Robert M; Scavone, Cristoforo

    2006-04-01

    Although the anti-inflammatory actions of glucocorticoids (GCs) are well established in the periphery, these stress hormones can increase inflammation under some circumstances in the brain. The transcription factor nuclear factor-kappaB (NF-kappaB), which is inhibited by GCs, regulates numerous genes central to inflammation. In this study, the effects of stress, GCs, and NMDA receptors on lipopolysaccharide (LPS)-induced activation of NF-kappaB in the brain were investigated. One day after chronic unpredictable stress (CUS), nonstressed and CUS rats were treated with saline or LPS and killed 2 h later. CUS potentiated the increase in LPS-induced activation of NF-kappaB in frontal cortex and hippocampus but not in the hypothalamus. This stress effect was blocked by pretreatment of rats with RU-486, an antagonist of the GC receptor. MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate], an NMDA receptor antagonist, also reduced the effect of LPS in all three brain regions. However, the combined antagonism of both GC and NMDA receptors produced no further reduction in NF-kappaB activation when compared with the effect of each treatment alone. Our results indicate that stress, via GC secretion, can increase LPS-induced NF-kappaB activation in the frontal cortex and hippocampus, agreeing with a growing literature demonstrating proinflammatory effects of GCs.

  19. Silymarin preconditioning protected insulin resistant rats from liver ischemia-reperfusion injury: role of endogenous H2S.

    Science.gov (United States)

    Younis, Nahla N; Shaheen, Mohamed A; Mahmoud, Mona F

    2016-08-01

    Hydrogen sulfide (H2S) can protect against hepatic ischemia-reperfusion injury (HIR). However, it is unknown whether it can protect against HIR in insulin resistance. This study investigated the protective effects of silymarin against HIR in a rat model of insulin resistance and the possible involvement of endogenous H2S. Insulin resistance was first established using 10% fructose in drinking water for 10 weeks. HIR was conducted in fructose-fed rats treated with saline or silymarin (100 mg/kg), 15 min before HIR (30 min ischemia, followed by 1 h reperfusion). Insulin resistance and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), total nitrites (NO2(-)), and H2S were measured. Hepatic malondialdehyde (MDA), reduced glutathione (GSH), hydroxyproline, H2S synthesizing activity, and mRNA expression of cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) were determined. Additionally, histopathological examination involved H&E, Sirius red, and caspase-3 immunostaining. Fructose-induced insulin resistance increased serum ALT, TNF-α, H2S and H2S synthesizing activity, and hepatic MDA, hydroxyproline, and CSE mRNA and decreased NO2(-) and GSH. These changes exacerbated the HIR injury in which endogenous H2S production was auxiliary increased. Silymarin preconditioning decreased ALT, AST, MDA, NO2(-), TNF-α, and TNF-α/IL-10 ratio, increased GSH, IL-10, improved hepatic architecture, and lowered caspase-3 immunostaining. Serum H2S, its hepatic synthesizing activity, and CSE and CBS mRNA expressions were all suppressed by silymarin pretreatment. The increases in endogenous H2S exacerbate HIR injury, whereas silymarin preconditioning protected against HIR in insulin resistant rats via powerful antioxidant, anti-inflammatory, and antiapoptotic effects along with suppressing H2S production. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. The correlation between CYP2D6 isoenzyme activity and haloperidol efficacy and safety profile in patients with alcohol addiction during the exacerbation of the addiction

    Science.gov (United States)

    Sychev, Dmitry Alekseevich; Zastrozhin, Mikhail Sergeevich; Smirnov, Valery Valerieevich; Grishina, Elena Anatolievna; Savchenko, Ludmila Mikhailovna; Bryun, Evgeny Alekseevich

    2016-01-01

    Background Today, it is proved that isoenzymes CYP2D6 and CYP3A4 are involved in metabolism of haloperidol. In our previous investigation, we found a medium correlation between the efficacy and safety of haloperidol and the activity of CYP3A4 in patients with alcohol abuse. Objective The aim of this study was to evaluate the correlation between the activity of CYP2D6 and the efficacy and safety of haloperidol in patients with diagnosed alcohol abuse. Methods The study involved 70 men (average age: 40.83±9.92 years) with alcohol addiction. A series of psychometric scales were used in the research. The activity of CYP2D6 was evaluated by high-performance liquid chromatography with mass spectrometry using the ratio of 6-hydroxy-1,2,3,4-tetrahydro-beta-carboline to pinoline. Genotyping of CYP2D6 (1846G>A) was performed using real-time polymerase chain reaction. Results According to results of correlation analysis, statistically significant values of Spearman correlation coefficient (rs) between the activity of CYP2D6 and the difference of points in psychometric scale were obtained in patients receiving haloperidol in injection form (Sheehan Clinical Anxiety Rating Scale =−0.721 [P<0.001] and Udvald for Kliniske Undersogelser Side Effect Rating Scale =0.692 [P<0.001]) and in those receiving haloperidol in tablet form (Covi Anxiety Scale =−0.851 [P<0.001] and Udvald for Kliniske Undersogelser Side Effect Rating Scale =0.797 [P<0.001]). Conclusion This study demonstrated the correlations between the activity of CYP2D6 isozyme and the efficacy and safety of haloperidol in patients with alcohol addiction. PMID:27695358

  1. Cortisone induces insulin resistance in C2C12 myotubes through activation of 11beta-hydroxysteroid dehydrogenase 1 and autocrinal regulation.

    Science.gov (United States)

    Park, Seung Yeon; Bae, Ji Hyun; Cho, Young Sik

    2014-04-01

    The enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) is known to catalyse inactive glucocorticoids into active forms, and its dysregulation in adipose and muscle tissues has been implicated in the development of metabolic syndrome. To delineate the molecular mechanism by which active cortisol has an antagonizing effect against insulin, we optimized the metabolic production of cortisol and its biological functions in myotubes (C2C12). Myotubes supplemented with cortisone actively catalysed its conversion into cortisol, which in turn abolished phosphorylation of Akt in response to insulin treatment. This led to diminished uptake of insulin-induced glucose. This was corroborated by the application of 11β-HSD1 inhibitor glycyrrhetinic acid and a glucocorticoid receptor antagonist RU-486, which reversed completely the antagonizing effects of cortisol on insulin action. Therefore, development of specific inhibitors targeting 11β-HSD1 might be a promising way to improve impaired insulin-stimulated glucose uptake. Copyright © 2013 John Wiley & Sons, Ltd.

  2. Effects of poly (lactic-co-glycolic acid) as a co-emulsifier on the preparation and hypoglycaemic activity of insulin-loaded solid lipid nanoparticles.

    Science.gov (United States)

    Wang, S L; Xie, S Y; Zhu, L Y; Wang, F H; Zhou, W Z

    2009-12-01

    Poly (lactic-co-glycolic acid) (PLGA) was used as a co-emulsifier in the preparation of insulin-loaded solid lipid nanoparticles (SLN) with hydrogenated castor oil as lipid matrix and lecithin as surfactant by double-emulsion technique. The effects of PLGA on the preparation and hypoglycaemic activity of insulin-loaded SLN were studied. The results showed that with the supplement of PLGA, the encapsulation efficiency and loading capacity were increased significantly from 79.08 +/- 1.62 to 85.57 +/- 3.21% and 1.58 +/- 0.03 to 1.71 +/- 0.06%, whereas the surface charge and particle size were changed insignificantly from -25.87 +/- 2.65 to -22.67 +/- 1.19 mv and 431.0 +/- 16.1 to 397.0 +/- 68.0 nm, respectively. In vivo studies demonstrated that PLGA increased the sustained hypoglycaemic activity from 12 to 36 h and 24 to 120 h in normal and steptozotocin-induced diabetic mice after a single intramuscular injection of the insulin-loaded SLN. These results demonstrated that PLGA could enhance the entrapment of insulin in the nanoparticles, and more importantly, prolong the time of hypoglycaemic activity of the insulin-loaded SLN.

  3. Transcriptome and Proteome Expressions Involved in Insulin Resistance in Muscle and Activated T-Lymphocytes of Patients with Type 2 Diabetes

    Institute of Scientific and Technical Information of China (English)

    Frankie; B.; Stentz; Abbas; E.; Kitabchi

    2007-01-01

    We analyzed the genes expressed (transcriptomes) and the proteins translated (pro- teomes) in muscle tissues and activated CD4+ and CD8+ T-lymphocytes (T-cells) of five Type 2 diabetes (T2DM) subjects using Affymetrix microarrays and mass spectrometry, and compared them with matched non-diabetic controls. Gene ex- pressions of insulin receptor (INSR), vitamin D receptor, insulin degrading enzyme, Akt, insulin receptor substrate-1 (IRS-1), IRS-2, glucose transporter 4 (GLUT4), and enzymes of the glycolytic pathway were decreased at least 50% in T2DM than in controls. However, there was greater than two-fold gene upregulation of plasma cell glycoprotein-1, tumor necrosis factor α (TNFα), and gluconeogenic enzymes in T2DM than in controls. The gene silencing for INSR or TNFα resulted in the inhibition or stimulation of GLUT4, respectively. Proteome profiles correspond- ing to molecular weights of the above translated transcriptomes showed different patterns of changes between T2DM and controls. Meanwhile, changes in tran- scriptomes and proteomes between muscle and activated T-cells of T2DM were comparable. Activated T-cells, analogous to muscle cells, expressed insulin sig- naling and glucose metabolism genes and gene products. In conclusion, T-cells and muscle in T2DM exhibited differences in expression of certain genes and gene products relative to non-diabetic controls. These alterations in transcriptomes and proteomes in T2DM may be involved in insulin resistance.

  4. The Adipose Renin-Angiotensin System Modulates Systemic Markers of Insulin Sensitivity and Activates the Intrarenal Renin-Angiotensin System

    Directory of Open Access Journals (Sweden)

    Suyeon Kim

    2006-01-01

    Full Text Available Background. The adipose tissue renin-angiotensin system (RAS contributes to regulation of fat mass and may also impact systemic functions such as blood pressure and metabolism. Methods and results. A panel of mouse models including mice lacking angiotensinogen, Agt (Agt-KO, mice expressing Agt solely in adipose tissue (aP2-Agt/Agt-KO, and mice overexpressing Agt in adipose tissue (aP2-Agt was studied. Total body weight, epididymal fat pad weight, and circulating levels of leptin, insulin, and resistin were significantly decreased in Agt-KO mice, while plasma adiponectin levels were increased. aP2-Agt mice exhibited increased adiposity and plasma leptin and insulin levels compared to wild type (WT controls. Angiotensinogen and type I Ang II receptor protein levels were also elevated in kidney of aP2-Agt mice. Conclusion. These findings demonstrate that alterations in adipose RAS activity significantly impact both local and systemic physiology in a way that may contribute to the detrimental health effects of obesity.

  5. The correlation between CYP2D6 isoenzyme activity and haloperidol efficacy and safety profile in patients with alcohol addiction during the exacerbation of the addiction

    Directory of Open Access Journals (Sweden)

    Sychev DA

    2016-09-01

    Full Text Available Dmitry Alekseevich Sychev,1 Mikhail Sergeevich Zastrozhin,1–3 Valery Valerieevich Smirnov,4 Elena Anatolievna Grishina,1 Ludmila Mikhailovna Savchenko,1 Evgeny Alekseevich Bryun1,2 1Russian Medical Academy of Postgraduate Education, Ministry of Health of the Russian Federation, 2Department of Public Health, Moscow Research and Practical Centre for Narcology, 3Peoples’ Friendship University of Russia, 4National Research Center, Institute of Immunology Federal Medical-Biological Agency of Russia, Moscow, Russia Background: Today, it is proved that isoenzymes CYP2D6 and CYP3A4 are involved in metabolism of haloperidol. In our previous investigation, we found a medium correlation between the efficacy and safety of haloperidol and the activity of CYP3A4 in patients with alcohol abuse.Objective: The aim of this study was to evaluate the correlation between the activity of CYP2D6 and the efficacy and safety of haloperidol in patients with diagnosed alcohol abuse.Methods: The study involved 70 men (average age: 40.83±9.92 years with alcohol addiction. A series of psychometric scales were used in the research. The activity of CYP2D6 was evaluated by high-performance liquid chromatography with mass spectrometry using the ratio of 6-hydroxy-1,2,3,4-tetrahydro-beta-carboline to pinoline. Genotyping of CYP2D6 (1846G>A was performed using real-time polymerase chain reaction.Results: According to results of correlation analysis, statistically significant values of Spearman correlation coefficient (rs between the activity of CYP2D6 and the difference of points in psychometric scale were obtained in patients receiving haloperidol in injection form (Sheehan Clinical Anxiety Rating Scale =-0.721 [P<0.001] and Udvald for Kliniske Undersogelser Side Effect Rating Scale =0.692 [P<0.001] and in those receiving haloperidol in tablet form (Covi Anxiety Scale =-0.851 [P<0.001] and Udvald for Kliniske Undersogelser Side Effect Rating Scale =0.797 [P<0.001].Conclusion

  6. AMPK and insulin action

    DEFF Research Database (Denmark)

    Frøsig, Christian; Jensen, Thomas Elbenhardt; Jeppesen, Jacob

    2013-01-01

    The 5'-AMP-activated protein kinase (AMPK) is considered "a metabolic master-switch" in skeletal muscle reducing ATP- consuming processes whilst stimulating ATP regeneration. Within recent years, AMPK has also been proposed as a potential target to attenuate insulin resistance, although the exact...... role of AMPK is not well understood. Here we hypothesized that mice lacking a2AMPK activity in muscle would be more susceptible to develop insulin resistance associated with ageing alone or in combination with high fat diet. Young (~4 month) or old (~18 month) wild type and muscle specific a2AMPK...... kinase-dead mice on chow diet as well as old mice on 17 weeks of high fat diet were studied for whole body glucose homeostasis (OGTT, ITT and HOMA-IR), insulin signaling and insulin-stimulated glucose uptake in muscle. We demonstrate that high fat diet in old mice results in impaired glucose homeostasis...

  7. Kleptomania and Potential Exacerbating Factors

    Science.gov (United States)

    2011-01-01

    Kleptomania is an impulse control disorder that can cause significant impairment and serious consequences. Often, the condition is kept secret by the patient, and usually help is sought only when confronted by the legal consequences of the impulsive behaviors. Historically, kleptomania has been viewed from a psychodynamic perspective, and the mainstay of treatment has been psychotherapy. Recently, attempts to explain kleptomania within a neuropsychiatric paradigm have highlighted the possible links between mood disorders, addictive behaviors, and brain injury with kleptomania. These associations with kleptomania can be extrapolated to pharmacological strategies that can potentially help in treating kleptomania. A case of kleptomania, which was potentially exacerbated by multiple factors, will be reviewed. Treatment modalities used in this case, including the use of the Yale-Brown Obsessive Compulsive Scale as a surrogate marker to gauge response to treatment, will be discussed. PMID:22132369

  8. Adiponectin induced AMP-activated protein kinase impairment mediates insulin resistance in Bama mini-pig fed high-fat and high-sucrose diet

    Directory of Open Access Journals (Sweden)

    Miaomiao Niu

    2017-08-01

    Full Text Available Objective Adipose tissue is no longer considered as an inert storage organ for lipid, but instead is thought to play an active role in regulating insulin effects via secretion adipokines. However, conflicting reports have emerged regarding the effects of adipokines. In this study, we investigated the role of adipokines in glucose metabolism and insulin sensitivity in obese Bama mini-pigs. Methods An obesity model was established in Bama mini-pigs, by feeding with high-fat and high-sucrose diet for 30 weeks. Plasma glucose and blood biochemistry levels were measured, and intravenous glucose tolerance test was performed. Adipokines, including adiponectin, interleukin-6 (IL-6, resistin and tumor necrosis factor alpha (TNF-α, and glucose-induced insulin secretion were also examined by radioimmunoassay. AMP-activated protein kinase (AMPK phosphorylation in skeletal muscle, which is a useful insulin resistance marker, was examined by immunoblotting. Additionally, associations of AMPK phosphorylation with plasma adipokines and homeostasis model assessment of insulin resistance (HOMA-IR index were assessed by Pearce’s correlation analysis. Results Obese pigs showed hyperglycemia, high triglycerides, and insulin resistance. Adiponectin levels were significantly decreased (p<0.05 and IL-6 amounts dramatically increased (p<0.05 in obese pigs both in serum and adipose tissue, corroborating data from obese mice and humans. However, circulating resistin and TNF-α showed no difference, while the values of TNF-α in adipose tissue were significantly higher in obese pigs, also in agreement with data from obese humans but not rodent models. Moreover, strong associations of skeletal muscle AMPK phosphorylation with plasma adiponectin and HOMA-IR index were obtained. Conclusion AMPK impairment induced by adiponectin decrease mediates insulin resistance in high-fat and high-sucrose diet induction. In addition, Bama mini-pig has the possibility of a conformable

  9. The insulin secretory action of novel polycyclic guanidines: discovery through open innovation phenotypic screening, and exploration of structure-activity relationships.

    Science.gov (United States)

    Shaghafi, Michael B; Barrett, David G; Willard, Francis S; Overman, Larry E

    2014-02-15

    We report the discovery of the glucose-dependent insulin secretogogue activity of a novel class of polycyclic guanidines through phenotypic screening as part of the Lilly Open Innovation Drug Discovery platform. Three compounds from the University of California, Irvine, 1-3, having the 3-arylhexahydropyrrolo[1,2-c]pyrimidin-1-amine scaffold acted as insulin secretagogues under high, but not low, glucose conditions. Exploration of the structure-activity relationship around the scaffold demonstrated the key role of the guanidine moiety, as well as the importance of two lipophilic regions, and led to the identification of 9h, which stimulated insulin secretion in isolated rat pancreatic islets in a glucose-dependent manner. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Serum and glucocorticoid-regulated kinase Sgk1 inhibits insulin-dependent activation of phosphomannomutase 2 in transfected COS-7 cells.

    Science.gov (United States)

    Menniti, Miranda; Iuliano, Rodolfo; Amato, Rosario; Boito, Rosalia; Corea, Monica; Le Pera, Ilaria; Gulletta, Elio; Fuiano, Giorgio; Perrotti, Nicola

    2005-01-01

    Serum- and glucocorticoid-regulated kinase (Sgk1) is considered to be an essential convergence point for peptide and steroid regulation of ENaC-mediated sodium transport. We tried to identify molecular partners of Sgk1 by yeast two-hybrid screening. Yeast two-hybrid screening showed a specific interaction between Sgk1 and phosphomannomutase (PMM)2, the latter of which is an enzyme involved in the regulation of glycoprotein biosynthesis. The interaction was confirmed in intact cells by coimmunoprecipitation and colocalization detected using confocal microscopy. We were then able to demonstrate that Sgk1 phosphorylated PMM2 in an in vitro assay. In addition, we found that the enzymatic activity of PMM2 is upregulated by insulin treatment and that Sgk1 completely inhibits PMM2 activity both in the absence and in the presence of insulin stimulation. These data provide evidence suggesting that Sgk1 may modulate insulin action on the cotranslational glycosylation of glycoproteins.

  11. The roots of Atractylodes japonica Koidzumi promote adipogenic differentiation via activation of the insulin signaling pathway in 3T3-L1 cells

    Directory of Open Access Journals (Sweden)

    Han Yunkyung

    2012-09-01

    Full Text Available Abstract Background Type 2 diabetes (T2D is a complex metabolic disorder characterized by insulin resistance and hyperglycemia. Peroxisome proliferator-activated receptor gamma (PPARγ is a key transcription factor and plays an important role in the regulation of genes involved in adipogenic differentiation, glucose metabolism and insulin signal transduction. Methods In this study, the effects of the root extract of Atractylodes japonica Koidzumi (Atractylodis Rhizoma Alba, ARA on the differentiation of 3T3-L1 preadipocytes and the possible mechanism of glucose transport were investigated. 3T3-L1 cells were cultured with insulin and ARA extract. Results In 3T3-L1 cells, ARA extract significantly enhanced adipogenic differentiation and upregulated the expression of PPARγ genes and protein in a dose-dependent manner. ARA also promoted glucose transport by increasing the glucose transporter 4 (GLUT-4, phosphatidylinositol 3-kinase (PI3K and insulin receptor substrates-1 (IRS-1 levels. Conclusion Our results suggest that ARA extract may be an attractive therapeutic agent for managing T2D via promoting the differentiation of adipocytes with the upregulation of PPARγ levels and the activation of the insulin signaling pathway.

  12. Linoleic Acid Activates GPR40/FFA1 and Phospholipase C to Increase [Ca2+]i Release and Insulin Secretion in Islet Beta-Cells

    Institute of Scientific and Technical Information of China (English)

    Yi-jun Zhou; Yu-ling Song; Hui Zhou; Yan Li

    2012-01-01

    To elucidate GPR40/FFA 1 and its downstream signaling pathways in regulating insulin secretion.Methods GPR40/FFA 1 expression was detected by immunofluorescence imaging.We employed linoleic acid (LA),a free fatty acid that has a high affinity to the rat GPR40,and examined its effect on cytosolic free calcium concentration ([Ca2+]i) in primary rat β-cells by Fluo-3 intensity under confocal microscopy recording.Downregulation of GPR40/FFA1 expression by antisense oligonucleotides was performed in pancreatic β-cells,and insulin secretion was assessed by enzyme-linked immunosorbent assay.Results LA acutely stimulated insulin secretion from primary cultured rat pancreatic islets.LA induced significant increase of [Ca2+]i in the presence of 5.6 mmol/L and 11.1 mmol/L glucose,which was reflected by increased Fluo-3 intensity under confocal microscopy recording.LA-stimulated increase in [Ca2+]i and insulin secretion were blocked by inhibition of GPR40/FFA1 expression in β-cells after GPR40/FFA1-specific antisense treatment.In addition,the inhibition of phospholipase C (PLC) activity by U73122,PLC inhibitor,also markedly inhibited the LA-induced [Ca2+]i increase.Conclusion LA activates GPR40/FFA1 and PLC to stimulate Ca2+ release,resulting in an increase in [Ca2+]i and insulin secretion in rat islet β-cells.

  13. Assessment of Aerobic Exercise Adverse Effects during COPD Exacerbation Hospitalization

    Directory of Open Access Journals (Sweden)

    Caroline Knaut

    2017-01-01

    Full Text Available Introduction. Aerobic exercise performed after hospital discharge for exacerbated COPD patients is already recommended to improve respiratory and skeletal muscle strength, increase tolerance to activity, and reduce the sensation of dyspnea. Previous studies have shown that anaerobic activity can clinically benefit patients hospitalized with exacerbated COPD. However, there is little information on the feasibility and safety of aerobic physical activity performed by patients with exacerbated COPD during hospitalization. Objective. To evaluate the effects of aerobic exercise on vital signs in hospitalized patients with exacerbated COPD. Patients and Methods. Eleven COPD patients (63% female, FEV1: 34.2 ± 13.9% and age: 65 ± 11 years agreed to participate. Aerobic exercise was initiated 72 hours after admission on a treadmill; speed was obtained from the distance covered in a 6-minute walk test (6MWT. Vital signs were assessed before and after exercise. Results. During the activity systolic blood pressure increased from 125.2 ± 13.6 to 135.8 ± 15.0 mmHg (p=0.004 and respiratory rate from 20.9 ± 4.4 to 24.2 ± 4.5 rpm (p=0.008 and pulse oximetry (SpO2 decreased from 93.8 ± 2.3 to 88.5 ± 5.7% (p<0.001. Aerobic activity was considered intense, heart rate ranged from 99.2 ± 11.5 to 119.1 ± 11.1 bpm at the end of exercise (p=0.092, and patients reached on average 76% of maximum heart rate. Conclusion. Aerobic exercise conducted after 72 hours of hospitalization in patients with exacerbated COPD appears to be safe.

  14. The Drosophila insulin-degrading enzyme restricts growth by modulating the PI3K pathway in a cell-autonomous manner.

    Science.gov (United States)

    Galagovsky, Diego; Katz, Maximiliano J; Acevedo, Julieta M; Sorianello, Eleonora; Glavic, Alvaro; Wappner, Pablo

    2014-03-01

    Mammalian insulin-degrading enzyme (IDE) cleaves insulin, among other peptidic substrates, but its function in insulin signaling is elusive. We use the Drosophila system to define the function of IDE in the regulation of growth and metabolism. We find that either loss or gain of function of Drosophila IDE (dIDE) can restrict growth in a cell-autonomous manner by affecting both cell size and cell number. dIDE can modulate Drosophila insulin-like peptide 2 levels, thereby restricting activation of the phosphatidylinositol-3-phosphate kinase pathway and promoting activation of Drosophila forkhead box, subgroup O transcription factor. Larvae reared in high sucrose exhibit delayed developmental timing due to insulin resistance. We find that dIDE loss of function exacerbates this phenotype and that mutants display increased levels of circulating sugar, along with augmented expression of a lipid biosynthesis marker. We propose that dIDE is a modulator of insulin signaling and that its loss of function favors insulin resistance, a hallmark of diabetes mellitus type II.

  15. Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages.

    Directory of Open Access Journals (Sweden)

    Mirko Lanuti

    Full Text Available The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

  16. Epigallocatechin gallate exacerbates fluoride-induced oxidative stress mediated testicular toxicity in rats through the activation of Nrf2 signaling pathway

    Institute of Scientific and Technical Information of China (English)

    S. Thangapandiyan; S. Miltonprabu

    2015-01-01

    Objective:To explore the ameliorative potential of epigallocatechin gallate (EGCG) by evaluating markers of oxidative stress, apoptosis, and inflammation and antioxidant competence in Fl intoxicated rats.Methods:The animals were divided in to four groups that is control, EGCG alone, NaF, and EGCG with NaF. Group III animal were exposed to Fl as sodium Fluoride (NaF) (25 mg/kg BW) for 4 weeks. After the completion of the treatment, the testis tissues has been removed and used for the experimental observations.Results:Pre-administration of EGCG to Fl intoxicated rats showed a significant normalization in the levels of steroidogenic enzymes, testosterone, sperm functions, oxidative stress markers and antioxidant status. The altered levels of proinflammatory cytokines and apoptotic markers were also relapsed in close proximity to control. In addition, EGCG significantly improved antioxidant status and reduced the oxidative stress and pathological changes in testes. The mRNA and protein analysis also substantiated that EGCG pre-treatment markedly enhanced the expression of Nrf2 and its target genes HO-1, NQO1 andγGCS and suppressed the expression of Keap1 in testis.Conclusion: Altogether, our findings supports that EGCG attenuates Fl toxicity in testis through Nrf2 activation.

  17. Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages.

    Science.gov (United States)

    Lanuti, Mirko; Talamonti, Emanuela; Maccarrone, Mauro; Chiurchiù, Valerio

    2015-01-01

    The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9)-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

  18. Synthesis, structure-activity relationships and brain uptake of a novel series of benzopyran inhibitors of insulin-regulated aminopeptidase.

    Science.gov (United States)

    Mountford, Simon J; Albiston, Anthony L; Charman, William N; Ng, Leelee; Holien, Jessica K; Parker, Michael W; Nicolazzo, Joseph A; Thompson, Philip E; Chai, Siew Yeen

    2014-02-27

    Peptide inhibitors of insulin-regulated aminopeptidase (IRAP) enhance fear avoidance and spatial memory and accelerate spatial learning in a number of memory paradigms. Using a virtual screening approach, a series of benzopyran compounds was identified that inhibited the catalytic activity of IRAP, ultimately resulting in the identification of potent and specific inhibitors. The present study describes the medicinal chemistry campaign that led to the development of the lead candidate, 3, highlighting the key structural features considered as critical for binding. Furthermore, the in vivo pharmacokinetics and brain uptake of compounds (1 and 3) were assessed in rats and were complemented with in vitro human and rat microsomal stability studies. Following intravenous administration to rodents, 3 exhibits brain exposure, albeit it is rapidly converted to 1, a compound which also exhibits potent inhibition of IRAP.

  19. Daily physical activity predicts degree of insulin resistance: a cross-sectional observational study using the 2003-2004 National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Nelson, Rachael K; Horowitz, Jeffrey F; Holleman, Robert G; Swartz, Ann M; Strath, Scott J; Kriska, Andrea M; Richardson, Caroline R

    2013-01-28

    This study examined the independent association of objectively measured physical activity on insulin resistance while controlling for confounding variables including: cardiorespiratory fitness, adiposity, sex, age, and smoking status. Data were obtained from National Health and Nutrition Examination Survey 2003-2004, a cross-sectional observational study conducted by the National Center for Health Statistics of the Centers for Disease Control that uses a stratified, multistage probability design to obtain a nationally representative sample of the U.S. population. The analysis included 402 healthy U.S. adults with valid accelerometer, cardiorespiratory fitness, and fasting plasma glucose and insulin concentrations. After controlling for relevant confounding variables we performed a multiple linear regression to predict homeostatic model of insulin resistance (HOMA-IR) based on average daily minutes of moderate-to-vigorous physical