Sample records for endogenous gaba concentration

  1. Impact of exogenous GABA treatments on endogenous GABA metabolism in anthurium cut flowers in response to postharvest chilling temperature. (United States)

    Aghdam, Morteza Soleimani; Naderi, Roohangiz; Jannatizadeh, Abbasali; Babalar, Mesbah; Sarcheshmeh, Mohammad Ali Askari; Faradonbe, Mojtaba Zamani


    Anthurium flowers are susceptible to chilling injury, and the optimum storage temperature is 12.5-20 °C. The γ-aminobutyric acid (GABA) shunt pathway may alleviate chilling stress in horticultural commodities by providing energy (ATP), reducing molecules (NADH), and minimizing accumulation of reactive oxygen species (ROS). In this experiment, the impact of a preharvest spray treatment with 1 mM GABA and postharvest treatment of 5 mM GABA stem-end dipping on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) in response to cold storage (4 °C for 21 days) was investigated. GABA treatments resulted in lower glutamate decarboxylase (GAD) and higher GABA transaminase (GABA-T) activities in flowers during cold storage, which was associated with lower GABA content and coincided with higher ATP content. GABA treatments also enhanced accumulation of endogenous glycine betaine (GB) in flowers during cold storage, as well as higher spathe relative water content (RWC). These findings suggest that GABA treatments may alleviate chilling injury of anthurium cut flowers by enhancing GABA shunt pathway activity leading to provide sufficient ATP and promoting endogenous GB accumulation. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  2. Treatment of germinated wheat to increase levels of GABA and IP6 catalyzed by endogenous enzymes. (United States)

    Nagaoka, Hiroyuki


    We found that the levels of bioactive products from wheat can be increased dramatically by manipulating germination conditions and taking advantage of the activity of endogenous enzymes. The yield of phytic acid (IP(6)) from wheat germinated in the presence of high, controlled levels of dissolved oxygen (188 +/- 28 mg/100 g wheat) was almost three times greater than that from wheat germinated with no supplemental oxygen (74 +/- 10 mg/100 g wheat). The yield of gamma-aminobutyric acid (GABA) from wheat germinated in the presence of uncontrolled levels of dissolved oxygen was 18 +/- 3 times greater than that from nonsupplemented wheat (1 mg/100 g wheat). The concentration of GABA was much greater in wheat germ than in whole wheat, and the yield of GABA from wheat germ processed with supplemental water (163 +/- 7 mg/100 g wheat germ) was notably greater than that from wheat germ processed with no supplemental water (100 +/- 2 mg/100 g wheat germ). In contrast, IP(6) was more concentrated in wheat bran, and the yield of IP(6) from wheat bran processed with supplemental water (3100 +/- 12 mg/100 g wheat bran) was notably higher than that from wheat bran processed with no supplemental water (2420 +/- 13 mg/100 g wheat bran). We conclude that the large amount of GABA extracted from wheat germ is likely due to high glutamate decarboxylase activity and low aminotransferase activity and that the large amount of IP(6) extracted from wheat bran is likely due to high levels of tyrosinase activity. Our findings indicate that bioactive molecules such as GABA and IP(6) can be successfully mass-produced by taking advantage of endogenous enzymatic activities.

  3. The endogenous GABA bioactivity of camel, bovine, goat and human milks. (United States)

    Limon, Agenor; Gallegos-Perez, Jose-Luis; Reyes-Ruiz, Jorge M; Aljohi, Mohammad A; Alshanqeeti, Ali S; Miledi, Ricardo


    GABA orally administered has several beneficial effects on health, including the regulation of hyperglycaemic states in humans. Those effects are similar to the effects reported for camel milk (CMk); however, it is not known whether compounds with GABAergic activity are present in milk from camels or other species. We determined CMk free-GABA concentration by LS/MS and its bioactivity on human GABA receptors. We found that camel and goat milks have significantly more bioavailable GABA than cow and human milks and are able to activate GABAρ receptors. The relationship between GABA and taurine concentrations suggests that whole camel milk may be more efficient to activate GABAρ1 receptors than goat milk. Because GABAρ receptors are normally found in enteroendocrine cells in the lumen of the digestive tract, these results suggest that GABA in camel and goat milk may participate in GABA-modulated functions of enteroendocrine cells in the GI lumen. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Demonstration of the dynamic mass redistribution label-free technology as a useful cell-based pharmacological assay for endogenously expressed GABAA receptors

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    Klein, Anders Bue; Nittegaard-Nielsen, Mia; Christensen, Julie T.


    the immortalized IMR-32 neuroblastoma cell line, which expresses relatively high levels of several endogenous GABAA receptor subunits, we show that GABA produces concentration-dependent cellular responses that can be measured and quantified in real-time. With the aid of the GABAA receptor-specific agonist muscimol...

  5. Presynaptic gain control by endogenous cotransmission of dopamine and GABA in the olfactory bulb. (United States)

    Vaaga, Christopher E; Yorgason, Jordan T; Williams, John T; Westbrook, Gary L


    In the olfactory bulb, lateral inhibition mediated by local juxtaglomerular interneurons has been proposed as a gain control mechanism, important for decorrelating odorant responses. Among juxtaglomerular interneurons, short axon cells are unique as dual-transmitter neurons that release dopamine and GABA. To examine their intraglomerular function, we expressed channelrhodopsin under control of the DAT-cre promoter and activated olfactory afferents within individual glomeruli. Optical stimulation of labeled cells triggered endogenous dopamine release as measured by cyclic voltammetry and GABA release as measured by whole cell GABAA receptor currents. Activation of short axon cells reduced the afferent presynaptic release probability via D2 and GABAB receptor activation, resulting in reduced spiking in both mitral and external tufted cells. Our results suggest that short axon cells influence glomerular activity not only by direct inhibition of external tufted cells but also by inhibition of afferent inputs to external tufted and mitral cells.NEW & NOTEWORTHY Sensory systems, including the olfactory system, encode information across a large dynamic range, making synaptic mechanisms of gain control critical to proper function. Here we demonstrate that a dual-transmitter interneuron in the olfactory bulb controls the gain of intraglomerular afferent input via two distinct mechanisms, presynaptic inhibition as well as inhibition of a principal neuron subtype, and thereby potently controls the synaptic gain of afferent inputs. Copyright © 2017 the American Physiological Society.

  6. Evidence that ethylenediamine acts in the isolated ileum of the guinea-pig by releasing endogenous GABA. (United States)

    Kerr, D. I.; Ong, J.


    Ethylenediamine (EDA) released [3H]-gamma-aminobutyric acid ([3H]-GABA) in a dose-dependent manner from the isolated preloaded ileum of the guinea-pig maintained in Krebs-bicarbonate solution (pH 7.4, 37 degrees C), in the presence of beta-alanine and amino-oxyacetic acid (AOAA) to prevent GABA uptake into glial cells and catabolism. This release was reversibly prevented by 3-mercaptopropionic acid (3-MPA), also in a dose-dependent manner. In the isolated ileal preparations of the guinea-pig maintained in Krebs-bicarbonate solution, EDA induced a dose-dependent transient, cholinergic contractile response (GABAA-receptor-mediated effect), followed by an 'after-relaxation' (GABAB-receptor-mediated effect). EDA also induced a transient contraction superimposed on repetitive twitch responses to electrical transmural stimulation of the cholinergic neurones, followed by a depression of the twitch contractions. This GABAA-receptor-mediated contraction was antagonized by bicuculline methochloride and picrotoxinin, whilst the GABAB-receptor-mediated 'after-relaxation', and depression of cholinergic twitch contractions, was susceptible to antagonism by delta-aminovaleric acid. The pA2 value for bicuculline methochloride antagonism of EDA was estimated to be 5.8, identical with that for GABA. 3-Mercaptopropionic acid also prevented these pharmacological actions induced by EDA without affecting responses to GABA, 3-aminopropranesulphonic acid, muscimol, baclofen or the twitch responses to transmural stimulation. It is concluded that EDA releases both [3H]-GABA and endogenous GABA in the guinea-pig ileum, thus providing further evidence that GABA is a transmitter in the enteric nervous system. PMID:6487887

  7. Photolysis of Caged-GABA Rapidly Terminates Seizures In Vivo: Concentration and Light Intensity Dependence

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    Dan Wang


    Full Text Available The therapy of focal epilepsy remains unsatisfactory for as many as 25% of patients. The photolysis of caged-γ-aminobutyric acid (caged-GABA represents a novel and alternative option for the treatment of intractable epilepsy. Our previous experimental results have demonstrated that the use of blue light produced by light-emitting diode to uncage ruthenium-bipyridine-triphenylphosphine-c-GABA (RuBi-GABA can rapidly terminate paroxysmal seizure activity both in vitro and in vivo. However, the optimal concentration of RuBi-GABA, and the intensity of illumination to abort seizures, remains unknown. The aim of this study was to explore the optimal anti-seizure effects of RuBi-GABA by using implantable fibers to introduce blue light into the neocortex of a 4-aminopyridine-induced acute seizure model in rats. We then investigated the effects of different combinations of RuBi-GABA concentrations and light intensity upon seizure. Our results show that the anti-seizure effect of RuBi-GABA has obvious concentration and light intensity dependence. This is the first example of using an implantable device for the photolysis of RuBi-GABA in the therapy of neocortical seizure, and an optimal combination of RuBi-GABA concentration and light intensity was explored. These results provide important experimental data for future clinical translational studies.

  8. GABA concentration in posterior cingulate cortex predicts putamen response during resting state fMRI.

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    Jorge Arrubla

    Full Text Available The role of neurotransmitters in the activity of resting state networks has been gaining attention and has become a field of research with magnetic resonance spectroscopy (MRS being one of the key techniques. MRS permits the measurement of γ-aminobutyric acid (GABA and glutamate levels, the central biochemical constituents of the excitation-inhibition balance in vivo. The inhibitory effects of GABA in the brain have been largely investigated in relation to the activity of resting state networks in functional magnetic resonance imaging (fMRI. In this study GABA concentration in the posterior cingulate cortex (PCC was measured using single voxel spectra acquired with standard point resolved spectroscopy (PRESS from 20 healthy male volunteers at 3 T. Resting state fMRI was consecutively measured and the values of GABA/Creatine+Phosphocreatine ratio (GABA ratio were included in a general linear model matrix as a step of dual regression analysis in order to identify voxels whose neuroimaging metrics during rest were related to individual levels of the GABA ratio. Our data show that the connection strength of putamen to the default-mode network during resting state has a negative linear relationship with the GABA ratio measured in the PCC. These findings highlight the role of PCC and GABA in segregation of the motor input, which is an inherent condition that characterises resting state.

  9. GABA(A) receptor alpha4 subunit suppression prevents withdrawal properties of an endogenous steroid. (United States)

    Smith, S S; Gong, Q H; Hsu, F C; Markowitz, R S; ffrench-Mullen, J M; Li, X


    The hormone progesterone is readily converted to 3alpha-OH-5alpha-pregnan-20-one (3alpha,5alpha-THP) in the brains of males and females. In the brain, 3alpha,5alpha-THP acts like a sedative, decreasing anxiety and reducing seizure activity, by enhancing the function of GABA (gamma-aminobutyric acid), the brain's major inhibitory neurotransmitter. Symptoms of premenstrual syndrome (PMS), such as anxiety and seizure susceptibility, are associated with sharp declines in circulating levels of progesterone and, consequently, of levels of 3alpha,5alpha-THP in the brain. Abrupt discontinuation of use of sedatives such as benzodiazepines and ethanol can also produce PMS-like withdrawal symptoms. Here we report a progesterone-withdrawal paradigm, designed to mimic PMS and post-partum syndrome in a rat model. In this model, withdrawal of progesterone leads to increased seizure susceptibility and insensitivity to benzodiazepine sedatives through an effect on gene transcription. Specifically, this effect was due to reduced levels of 3alpha,5alpha-THP which enhance transcription of the gene encoding the alpha4 subunit of the GABA(A) receptor. We also find that increased susceptibility to seizure after progesferone withdrawal is due to a sixfold decrease in the decay time for GABA currents and consequent decreased inhibitory function. Blockade of the alpha4 gene transcript prevents these withdrawal properties. PMS symptoms may therefore be attributable, in part, to alterations in expression of GABA(A) receptor subunits as a result of progesterone withdrawal.

  10. Decreased auditory GABA+ concentrations in presbycusis demonstrated by edited magnetic resonance spectroscopy. (United States)

    Gao, Fei; Wang, Guangbin; Ma, Wen; Ren, Fuxin; Li, Muwei; Dong, Yuling; Liu, Cheng; Liu, Bo; Bai, Xue; Zhao, Bin; Edden, Richard A E


    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central auditory system. Altered GABAergic neurotransmission has been found in both the inferior colliculus and the auditory cortex in animal models of presbycusis. Edited magnetic resonance spectroscopy (MRS), using the MEGA-PRESS sequence, is the most widely used technique for detecting GABA in the human brain. However, to date there has been a paucity of studies exploring changes to the GABA concentrations in the auditory region of patients with presbycusis. In this study, sixteen patients with presbycusis (5 males/11 females, mean age 63.1 ± 2.6 years) and twenty healthy controls (6 males/14 females, mean age 62.5 ± 2.3 years) underwent audiological and MRS examinations. Pure tone audiometry from 0.125 to 8 kHz and tympanometry were used to assess the hearing abilities of all subjects. The pure tone average (PTA; the average of hearing thresholds at 0.5, 1, 2 and 4 kHz) was calculated. The MEGA-PRESS sequence was used to measure GABA+ concentrations in 4 × 3 × 3 cm(3) volumes centered on the left and right Heschl's gyri. GABA+ concentrations were significantly lower in the presbycusis group compared to the control group (left auditory regions: p = 0.002, right auditory regions: p = 0.008). Significant negative correlations were observed between PTA and GABA+ concentrations in the presbycusis group (r = -0.57, p = 0.02), while a similar trend was found in the control group (r = -0.40, p = 0.08). These results are consistent with a hypothesis of dysfunctional GABAergic neurotransmission in the central auditory system in presbycusis and suggest a potential treatment target for presbycusis. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Altering the concentration of GABA in the synaptic cleft potentiates miniature IPSCs in rat occipital cortex. (United States)

    Perrais, D; Ropert, N


    We have tested the effect of dextran (40 kDa, 5%) on miniature IPSCs (mIPSCs) recorded in layer V cortical pyramidal cells. This compound increases the amplitude of mIPSCs at room and physiological temperatures by 15%, leaving their duration unaffected at room temperature and slightly increased at physiological temperature. The amplitude increase is attributable to an increase in the number of receptors bound by GABA during synaptic transmission, as shown by the occlusion between the effects of dextran and zolpidem on mIPSC amplitude at room temperature. As dextran presumably enhances the concentration and dwell time of GABA in the synaptic cleft, these results demonstrate that the postsynaptic GABAA receptors are not saturated at room and physiological temperatures.

  12. Regional GABA concentration and (/sup 3/H)-diazepam binding in rat brain following repeated electroconvulsive shock

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    Bowdler, J.M.; Green, A.R.; Minchin, M.C.W.; Nutt, D.J. (Radcliffe Infirmary, Oxford (UK))


    It has been confirmed that 24 hours following a series of electroconvulsive shocks (ECS) given once daily for 10 days (ECS x 10) to rats there is an increase in GABA concentration in the corpus striatum. A similar change was seen after the ECS had been given to rats anaesthetised with halothane, or when 5 ECS were given spread out over 10 days, the rats being anaesthetised during the ECS. A daily convulsion for 10 days elicited by flurothyl exposure resulted in an increased striatal GABA concentration, but also increased the GABA concentration in the hypothalamus, hippocampus and cortex. The increase in striatal GABA concentration was present 24 hours after ECS daily for 5 days or 3 days after ECS daily for 10 days. No change in (/sup 3/H)-diazepam binding was seen in hippocampus, cortex or corpus striatum 24 hours after the last of 10 once daily ECS. The increase in striatal GABA concentration was therefore seen at all times when enhanced monoaminemediated behaviours have been demonstrated following seizures.

  13. The role of γ -aminobutyric acid (Gaba) in somatic embryogenesis of Acca sellowiana Berg. (Myrtaceae)


    Booz, Maristela Raitz; Gilberto B. Kerbauy; Guerra, Miguel Pedro; Pescador, Rosete


    The γ-aminobutyric acid (Gaba) is a non-protein amino acid found in prokaryotes and eukaryotes. Its role in plant development has not been fully established. This study reports a quantification of the levels of endogenous Gaba, as well as investigation of its role in different stages of somatic embryogenesis in Acca sellowiana Berg. (Myrtaceae). Zygotic embryos were used as explants and they were inoculated into the culture medium contained different concentrations of Gaba (0,2, 4, 6, 8 ...

  14. Prefrontal Glx and GABA concentrations and impulsivity in cigarette smokers and smoking polysubstance users

    NARCIS (Netherlands)

    Schulte, Mieke H J; Kaag, Anne Marije; Wiers, Reinout W; Schmaal, Lianne; van den Brink, Wim; Reneman, Liesbeth; Homberg, Judith R; Van Wingen, G.; Goudriaan, Anna E


    Glutamate and GABA play an important role in substance dependence. However, it remains unclear whether this holds true for different substance use disorders and how this is related to risk-related traits such as impulsivity. We, therefore, compared Glx (as a proxy measure for glutamate) and GABA

  15. Effect of incubation time, buffer type and concentration on gamma-aminobutyric acid (GABA production using Khao Dawk Mali 105 rice bran

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    Apinya Eamarjharn


    Full Text Available Rice bran of Khao Dawk Mali 105 (KDML105 variety was selected for production of gamma-aminobutyric acid (GABA. The effect of incubation time on GABA production was studied and the maximum GABA was produced after 6 h of incubation. Different types of 50 mM buffers (containing 0.2% glutamic acid consisting of Tris, citric acid, boric acid and phosphate buffer (pH 5.6 were used to stabilize the pH of the reaction system. The highest GABA content (5.05 mg/g of bran was found in the phosphate buffer system. Therefore, the effect of phosphate buffer concentrations (0–200 mM on GABA production was investigated. The results showed that rice bran with phosphate buffer at a concentration of 80 mM at pH 5.6 with a rice bran to phosphate buffer at a ratio of 1–8 (weight per volume produced the highest GABA content (p ≤ 0.05. GABA production was increased about 2.7 times in the phosphate buffer system compared with the control and about 11 times compared to the initial GABA content (0.58 mg/g of bran in the rice bran. The results indicated that incubation time, buffer type and concentration significantly affect GABA production using rice bran.

  16. Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD activation and GABA concentration.

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    Ashley D Harris

    Full Text Available Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.

  17. Divergent influences of anterior cingulate cortex GABA concentrations on the emotion circuitry

    NARCIS (Netherlands)

    Levar, Nina; van Leeuwen, Judith M C; Denys, Damiaan; Van Wingen, G.


    Neuroimaging research has revealed that emotion processing recruits a widespread neural network including the dorsal anterior cingulate cortex (dACC), hippocampus, and amygdala. Recent studies have started to investigate the role of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA)

  18. Exploring the relationship between cortical GABA concentrations, auditory gamma-band responses and development in ASD: Evidence for an altered maturational trajectory in ASD. (United States)

    Port, Russell G; Gaetz, William; Bloy, Luke; Wang, Dah-Jyuu; Blaskey, Lisa; Kuschner, Emily S; Levy, Susan E; Brodkin, Edward S; Roberts, Timothy P L


    Autism spectrum disorder (ASD) is hypothesized to arise from imbalances between excitatory and inhibitory neurotransmission (E/I imbalance). Studies have demonstrated E/I imbalance in individuals with ASD and also corresponding rodent models. One neural process thought to be reliant on E/I balance is gamma-band activity (Gamma), with support arising from observed correlations between motor, as well as visual, Gamma and underlying GABA concentrations in healthy adults. Additionally, decreased Gamma has been observed in ASD individuals and relevant animal models, though the direct relationship between Gamma and GABA concentrations in ASD remains unexplored. This study combined magnetoencephalography (MEG) and edited magnetic resonance spectroscopy (MRS) in 27 typically developing individuals (TD) and 30 individuals with ASD. Auditory cortex localized phase-locked Gamma was compared to resting Superior Temporal Gyrus relative cortical GABA concentrations for both children/adolescents and adults. Children/adolescents with ASD exhibited significantly decreased GABA+/Creatine (Cr) levels, though typical Gamma. Additionally, these children/adolescents lacked the typical maturation of GABA+/Cr concentrations and gamma-band coherence. Furthermore, children/adolescents with ASD additionally failed to exhibit the typical GABA+/Cr to gamma-band coherence association. This altered coupling during childhood/adolescence may result in Gamma decreases observed in the adults with ASD. Therefore, individuals with ASD exhibit improper local neuronal circuitry maturation during a childhood/adolescence critical period, when GABA is involved in configuring of such circuit functioning. Provocatively a novel line of treatment is suggested (with a critical time window); by increasing neural GABA levels in children/adolescents with ASD, proper local circuitry maturation may be restored resulting in typical Gamma in adulthood. Autism Res 2017, 10: 593-607. © 2016 International Society for

  19. Changes in GABA and Glutamate concentrations during Memory Tasks in Patients with Parkinson’s disease undergoing DBS Surgery

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    Robert J Buchanan


    Full Text Available Until now direct neurochemical measurements during memory tasks have not been accomplished in the human basal ganglia. It has been proposed, based on both functional imaging studies and psychometric testing in normal subjects and in patients with Parkinson’s disease (PD, that the basal ganglia is responsible for the performance of feedback-contingent implicit memory tasks. To measure neurotransmitters, we used in-vivo microdialysis during deep brain stimulator (DBS surgery. We show in the right subthalamic nucleus (STN of patients with PD a task-dependent change in the concentrations of glutamate and GABA during an implicit memory task relative to baseline, while no difference was found between declarative memory tasks. The five patients studied had a significant decrease in the percent concentration of GABA and glutamate during the performance of the Weather Prediction Task (WPT. We hypothesize, based on current models of basal ganglia function, that this decrease in the concentration is consistent with expected dysfunction in basal ganglia networks in patients with Parkinson’s disease.

  20. Local GABA concentration is related to network-level resting functional connectivity. (United States)

    Stagg, Charlotte J; Bachtiar, Velicia; Amadi, Ugwechi; Gudberg, Christel A; Ilie, Andrei S; Sampaio-Baptista, Cassandra; O'Shea, Jacinta; Woolrich, Mark; Smith, Stephen M; Filippini, Nicola; Near, Jamie; Johansen-Berg, Heidi


    Anatomically plausible networks of functionally inter-connected regions have been reliably demonstrated at rest, although the neurochemical basis of these 'resting state networks' is not well understood. In this study, we combined magnetic resonance spectroscopy (MRS) and resting state fMRI and demonstrated an inverse relationship between levels of the inhibitory neurotransmitter GABA within the primary motor cortex (M1) and the strength of functional connectivity across the resting motor network. This relationship was both neurochemically and anatomically specific. We then went on to show that anodal transcranial direct current stimulation (tDCS), an intervention previously shown to decrease GABA levels within M1, increased resting motor network connectivity. We therefore suggest that network-level functional connectivity within the motor system is related to the degree of inhibition in M1, a major node within the motor network, a finding in line with converging evidence from both simulation and empirical studies. DOI:

  1. GABA, a natural immunomodulator of T lymphocytes

    DEFF Research Database (Denmark)

    Bjurstöm, Helen; Wang, Junyang; Ericsson, Ida


    gamma-aminobutyric acid (GABA) is the main neuroinhibitory transmitter in the brain. Here we show that GABA in the extracellular space may affect the fate of pathogenic T lymphocytes entering the brain. We examined in encephalitogenic T cells if they expressed functional GABA channels that could......M and higher GABA concentrations decreased T cell proliferation. The results are consistent with GABA being immunomodulatory....

  2. GABA predicts visual intelligence. (United States)

    Cook, Emily; Hammett, Stephen T; Larsson, Jonas


    Early psychological researchers proposed a link between intelligence and low-level perceptual performance. It was recently suggested that this link is driven by individual variations in the ability to suppress irrelevant information, evidenced by the observation of strong correlations between perceptual surround suppression and cognitive performance. However, the neural mechanisms underlying such a link remain unclear. A candidate mechanism is neural inhibition by gamma-aminobutyric acid (GABA), but direct experimental support for GABA-mediated inhibition underlying suppression is inconsistent. Here we report evidence consistent with a global suppressive mechanism involving GABA underlying the link between sensory performance and intelligence. We measured visual cortical GABA concentration, visuo-spatial intelligence and visual surround suppression in a group of healthy adults. Levels of GABA were strongly predictive of both intelligence and surround suppression, with higher levels of intelligence associated with higher levels of GABA and stronger surround suppression. These results indicate that GABA-mediated neural inhibition may be a key factor determining cognitive performance and suggests a physiological mechanism linking surround suppression and intelligence. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  3. Brain Gamma-Aminobutyric Acid (GABA) Concentration of the Prefrontal Lobe in Unmedicated Patients with Obsessive-Compulsive Disorder: A Research of Magnetic Resonance Spectroscopy. (United States)

    Zhang, Zongfeng; Fan, Qing; Bai, Yanle; Wang, Zhen; Zhang, Haiyin; Xiao, Zeping


    In recent years, a large number of neuroimaging studies found that the Cortico-Striato- Thalamo-Cortical circuit (CSTC), including the prefrontal lobe, a significant part of CSTC, has disturbance metabolically in patients with Obsessive-Compulsive Disorder (OCD). Explore the correlation between the neuro-metabolic features and clinical characteristics of OCD patients using magnetic resonance spectroscopy technology. 88 patients with OCD who were not received medication and outpatient treatment for 8 weeks and 76 health controls were enrolled, there was no significant difference in gender, age or education level between the two groups. SIEMENS 3.0T MRI scanner was used to measure the spectral wave of Orbito Frontal Cortex (OFC) and Anterior Cingulate Cortex (ACC) of participants, setting mega-press sequences. Meanwhile, the concentrations of gamma-aminobutyric acid (GABA), glutamine/glutamate complex (Glx) and N-Acetyl Aspartate (NAA) were measured relative to concentration of water, on the ACC and OFC of participants, for statistical analysis via LC model version 6.3 software. The concentration of metabolic substances of the OCD group compared to the healthy control group was analyzed using two sample t-test. The correlation between substance concentration and scores on the scales, including Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Hamilton Anxiety scale (HAMA) and Hamilton Depression scale (HAMD) was carried out using the Pearson correlation method. Compared with healthy controls, the GABA/W and NAA/W concentration in individuals with OCD are significantly decreased (p=0.031, t=2.193, p=0.002, t=3.223). Also, the concentration of GABA/W had a trend of decrease in the ACC. The GABA/W of the OFC had a negative correlation with Y-BOCS-O, Y-BOCS-C and Y-BOCS-T scores (p=0.037, r=0.221; p=0.007, r=0.283; p=0.014, r=0.259). These results support that GABA concentration in the OFC area of patients with OCD is significantly decreased and the concentration in the

  4. Ethanol, not detectably metabolized in brain, significantly reduces brain metabolism, probably via action at specific GABA(A) receptors and has measureable metabolic effects at very low concentrations. (United States)

    Rae, Caroline D; Davidson, Joanne E; Maher, Anthony D; Rowlands, Benjamin D; Kashem, Mohammed A; Nasrallah, Fatima A; Rallapalli, Sundari K; Cook, James M; Balcar, Vladimir J


    Ethanol is a known neuromodulatory agent with reported actions at a range of neurotransmitter receptors. Here, we measured the effect of alcohol on metabolism of [3-¹³C]pyruvate in the adult Guinea pig brain cortical tissue slice and compared the outcomes to those from a library of ligands active in the GABAergic system as well as studying the metabolic fate of [1,2-¹³C]ethanol. Analyses of metabolic profile clusters suggest that the significant reductions in metabolism induced by ethanol (10, 30 and 60 mM) are via action at neurotransmitter receptors, particularly α4β3δ receptors, whereas very low concentrations of ethanol may produce metabolic responses owing to release of GABA via GABA transporter 1 (GAT1) and the subsequent interaction of this GABA with local α5- or α1-containing GABA(A)R. There was no measureable metabolism of [1,2-¹³C]ethanol with no significant incorporation of ¹³C from [1,2-¹³C]ethanol into any measured metabolite above natural abundance, although there were measurable effects on total metabolite sizes similar to those seen with unlabelled ethanol. © 2013 International Society for Neurochemistry.

  5. Mapping absolute tissue endogenous fluorophore concentrations with chemometric wide-field fluorescence microscopy (United States)

    Xu, Zhang; Reilley, Michael; Li, Run; Xu, Min


    We report chemometric wide-field fluorescence microscopy for imaging the spatial distribution and concentration of endogenous fluorophores in thin tissue sections. Nonnegative factorization aided by spatial diversity is used to learn both the spectral signature and the spatial distribution of endogenous fluorophores from microscopic fluorescence color images obtained under broadband excitation and detection. The absolute concentration map of individual fluorophores is derived by comparing the fluorescence from "pure" fluorophores under the identical imaging condition following the identification of the fluorescence species by its spectral signature. This method is then demonstrated by characterizing the concentration map of endogenous fluorophores (including tryptophan, elastin, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide) for lung tissue specimens. The absolute concentrations of these fluorophores are all found to decrease significantly from normal, perilesional, to cancerous (squamous cell carcinoma) tissue. Discriminating tissue types using the absolute fluorophore concentration is found to be significantly more accurate than that achievable with the relative fluorescence strength. Quantification of fluorophores in terms of the absolute concentration map is also advantageous in eliminating the uncertainties due to system responses or measurement details, yielding more biologically relevant data, and simplifying the assessment of competing imaging approaches.

  6. tDCS-induced alterations in GABA concentration within primary motor cortex predict motor learning and motor memory: a 7 T magnetic resonance spectroscopy study. (United States)

    Kim, Soyoung; Stephenson, Mary C; Morris, Peter G; Jackson, Stephen R


    Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that alters cortical excitability in a polarity specific manner and has been shown to influence learning and memory. tDCS may have both on-line and after-effects on learning and memory, and the latter are thought to be based upon tDCS-induced alterations in neurochemistry and synaptic function. We used ultra-high-field (7 T) magnetic resonance spectroscopy (MRS), together with a robotic force adaptation and de-adaptation task, to investigate whether tDCS-induced alterations in GABA and Glutamate within motor cortex predict motor learning and memory. Note that adaptation to a robot-induced force field has long been considered to be a form of model-based learning that is closely associated with the computation and 'supervised' learning of internal 'forward' models within the cerebellum. Importantly, previous studies have shown that on-line tDCS to the cerebellum, but not to motor cortex, enhances model-based motor learning. Here we demonstrate that anodal tDCS delivered to the hand area of the left primary motor cortex induces a significant reduction in GABA concentration. This effect was specific to GABA, localised to the left motor cortex, and was polarity specific insofar as it was not observed following either cathodal or sham stimulation. Importantly, we show that the magnitude of tDCS-induced alterations in GABA concentration within motor cortex predicts individual differences in both motor learning and motor memory on the robotic force adaptation and de-adaptation task. Copyright © 2014. Published by Elsevier Inc.

  7. GABA Concentrations in the Anterior Cingulate Cortex Are Associated with Fear Network Function and Fear Recovery in Humans

    NARCIS (Netherlands)

    Levar, Nina; van Leeuwen, Judith M C; Puts, Nicolaas A J; Denys, Damiaan; Van Wingen, G.


    Relapse of fear after successful treatment is a common phenomenon in patients with anxiety disorders. Animal research suggests that the inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays a key role in the maintenance of extinguished fear. Here, we combined magnetic resonance spectroscopy

  8. GABA Concentrations in the Anterior Cingulate Cortex Are Associated with Fear Network Function and Fear Recovery in Humans

    NARCIS (Netherlands)

    Levar, Nina; van Leeuwen, Judith M. C.; Puts, Nicolaas A. J.; Denys, Damiaan; van Wingen, Guido A.


    Relapse of fear after successful treatment is a common phenomenon in patients with anxiety disorders. Animal research suggests that the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) plays a key role in the maintenance of extinguished fear. Here, we combined magnetic resonance

  9. Effects of glutamate decarboxylase and gamma-aminobutyric acid (GABA) transporter on the bioconversion of GABA in engineered Escherichia coli. (United States)

    Le Vo, Tam Dinh; Kim, Tae Wan; Hong, Soon Ho


    Gamma-aminobutyric acid (GABA) is a non-essential amino acid and a precursor of pyrrolidone, a monomer of nylon 4. GABA can be biosynthesized through the decarboxylation of L: -glutamate by glutamate decarboxylase. In this study, the effects of glutamate decarboxylase (gadA, gadB), glutamate/GABA antiporter (gadC) and GABA aminotransferase (gabT) on GABA production were investigated in Escherichia coli. Glutamate decarboxylase was overexpressed alone or with the glutamate/GABA antiporter to enhance GABA synthesis. GABA aminotransferase, which redirects GABA into the TCA cycle, was knock-out mutated. When gadB and gadC were co-overexpressed in the gabT mutant strain, a final GABA concentration of 5.46 g/l was obtained from 10 g/l of monosodium glutamate (MSG), which corresponded to a GABA yield of 89.5%.

  10. Allosteric modulation of retinal GABA receptors by ascorbic acid (United States)

    Calero, Cecilia I.; Vickers, Evan; Moraga Cid, Gustavo; Aguayo, Luis G.; von Gersdorff, Henrique; Calvo, Daniel J.


    Summary Ionotropic γ-aminobutyric acid receptors (GABAA and GABAC) belong to the cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA-puff evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ρ1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereospecific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two cys-loop cysteines and histidine 141, all located in the ρ1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. PMID:21715633

  11. Effect of insoluble calcium concentration on endogenous syneresis rate in rennet-coagulated bovine milk. (United States)

    Choi, J; Horne, D S; Lucey, J A


    The rennet coagulation of milk has been extensively studied. Mathematical modeling of the gelation process has been performed, mainly for the purpose of predicting the gel point. Rheological profiles of rennet gels during aging (long reaction times) have indicated that the gel stiffness (modulus) attains a maximum and thereafter decreases. We wanted to model this type of behavior and used the Carlson model, which includes terms for the proteolysis of κ-casein hairs (creating active sites) and the crosslinking of these activated sites. To account for the observed decrease in the gel modulus with time, we modified the Carlson model by adding an exponential decay term, which we ascribe to endogenous syneresis. We believe that this decay (i.e., syneresis rate) would likely be influenced by the mobility of bonds within casein micelles (in gels as indicated by the rheological loss tangent parameter). To modify the internal structural bonding of casein micelles, reconstituted skim milk was acidified to pH values 6.4, 6.0, 5.8, 5.6, and 5.4, or EDTA was added to milk at concentrations of 0, 2, 4, and 6mM, and the final pH values of EDTA-treated samples were subsequently adjusted to pH 6.0. These treatments were then used to prepare rennet gel samples that were monitored by dynamic low amplitude oscillatory rheometry. When the modified Carlson model was fitted to the actual experimental storage modulus values of each sample, it fitted the data reasonably well (especially the pH trial data). As the pH values of milk decreased, the modulus values at infinite reaction time (G'∞) increased; however, G'∞ decreased with an increase in the EDTA concentration. In the pH trial, the rate constants for the proteolysis of κ-casein hairs and the crosslinking of these activated sites exhibited a maximum at pH 5.6 and 6.0, respectively. The rate constant for endogenous syneresis increased at pH values rate constant for endogenous syneresis was significantly positively correlated (r

  12. GABA localization in the nematode Ascaris

    Energy Technology Data Exchange (ETDEWEB)

    Guastella, J.


    A histochemical approach was used to examine the distribution of GABA-associated neurons in the nematode Ascaris, an organism whose small number of morphologically simple neurons make it an excellent preparation for analyzing neuronal phenotypes. Two GABAergic markers were examined: GABA-like immunoreactivity (GLIR), a marker for endogenous stores of GABA; and ({sup 3}H)-GABA uptake, a marker for GABA uptake sites. Strong GLIR was present in the cell bodies, neurites and commissures of dorsal and ventral inhibitory motorneurons present in this region. Strong GLIR was also present in the cell bodies and processes of the four RME neurons in the nerve ring and in several other ganglionic neurons. Staining was absent in excitatory motorneurons, in ventral cord interneurons and in muscle cells and hypodermis. GABA uptake sites were found in single neural processes in both the ventral and dorsal nerve cords. ({sup 3}H)-GABA labeling was also observed in the other two RME cells and several other cephalic neurons. Four putative cholinergic excitatory motorneurons in the retrovesicular ganglion (RVG) were heavily labeled. Ventral and dorsal nerve cord inhibitory motorneurons did not take up ({sup 3}H)-GABA. Labeling of the ventral cord excitatory motorneuron somata and cell bodies was at or slightly above background. Heavy labeling of muscle cells was also observed.

  13. Extreme concentrations of endogenous sex hormones, ischemic heart disease, and death in women

    DEFF Research Database (Denmark)

    Benn, Marianne; Voss, Sidsel Skou; Holmegard, Haya N.


    Heart Study. During ≤30 years of follow-up, 1013 women developed ischemic heart disease and 2716 died. In women with a plasma estradiol below the fifth percentile compared with between the 10th and 89th percentiles, multifactorially adjusted risk of ischemic heart disease was 44% (95% confidence......OBJECTIVE - : Sex hormones may be critical determinants of ischemic heart disease and death in women, but results from previous studies are conflicting. To clarify this, we tested the hypothesis that extreme plasma concentrations of endogenous estradiol and testosterone are associated with risk...... of ischemic heart disease and death in women. APPROACH AND RESULTS - : In a nested prospective cohort study, we measured plasma estradiol in 4600 and total testosterone in 4716 women not receiving oral contraceptives or hormonal replacement therapy from the 1981 to 1983 examination of the Copenhagen City...

  14. Distribution of 3H-GABA uptake sites in the nematode Ascaris

    Energy Technology Data Exchange (ETDEWEB)

    Guastella, J.; Stretton, A.O. (University of Wisconsin, Madison (USA))


    The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, located at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.

  15. Action of bicyclic isoxazole GABA analogues on GABA transporters and its relation to anticonvulsant activity

    DEFF Research Database (Denmark)

    Bolvig, T; Larsson, O M; Pickering, D S


    The inhibitory action of bicyclic isoxazole gamma-aminobutyric acid (GABA) analogues and their 4,4-diphenyl-3-butenyl (DPB) substituted derivatives has been investigated in cortical neurones and astrocytes as well as in human embryonic kidney (HEK 293) cells transiently expressing either mouse GABA...... anticonvulsant activity, lack of proconvulsant activity and the ability of THPO to increase extracellular GABA concentration, indicate that these bicyclic isoxazole GABA analogues and their DPB derivatives may be useful lead structures in future search for new antiepileptic drugs....

  16. GABA receptor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Doo [Yonsei University College of Medicine, Seoul (Korea, Republic of)


    GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA{sub A}-receptor that allows chloride to pass through a ligand gated ion channel and GABA{sub B}-receptor that uses G-proteins for signaling. The GABA{sub A}-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA{sub A}-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with {sup 11}C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, {sup 18}F-fluoroflumazenil (FFMZ) has been developed to overcome {sup 11}C's short half-life. {sup 18}F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1{sup 1}C-FMZ PET instead of {sup 18}F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA{sub A} receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

  17. Revised Ion/Substrate Coupling Stoichiometry of GABA Transporters. (United States)

    Eskandari, Sepehr; Willford, Samantha L; Anderson, Cynthia M


    The purpose of this review is to highlight recent evidence in support of a 3 Na + : 1 Cl - : 1 GABA coupling stoichiometry for plasma membrane GABA transporters (SLC6A1 , SLC6A11 , SLC6A12 , SLC6A13 ) and how the revised stoichiometry impacts our understanding of the contribution of GABA transporters to GABA homeostasis in synaptic and extrasynaptic regions in the brain under physiological and pathophysiological states. Recently, our laboratory probed the GABA transporter stoichiometry by analyzing the results of six independent measurements, which included the shifts in the thermodynamic transporter reversal potential caused by changes in the extracellular Na + , Cl - , and GABA concentrations, as well as the ratio of charge flux to substrate flux for Na + , Cl - , and GABA under voltage-clamp conditions. The shifts in the transporter reversal potential for a tenfold change in the external concentration of Na + , Cl - , and GABA were 84 ± 4, 30 ± 1, and 29 ± 1 mV, respectively. Charge flux to substrate flux ratios were 0.7 ± 0.1 charges/Na + , 2.0 ± 0.2 charges/Cl - , and 2.1 ± 0.1 charges/GABA. We then compared these experimental results with the predictions of 150 different transporter stoichiometry models, which included 1-5 Na + , 0-5 Cl - , and 1-5 GABA per transport cycle. Only the 3 Na + : 1 Cl - : 1 GABA stoichiometry model correctly predicts the results of all six experimental measurements. Using the revised 3 Na + : 1 Cl - : 1 GABA stoichiometry, we propose that the GABA transporters mediate GABA uptake under most physiological conditions. Transporter-mediated GABA release likely takes place under pathophysiological or extreme physiological conditions.

  18. Measurement of the endogenous adenosine concentration in humans in vivo: methodological considerations.

    NARCIS (Netherlands)

    Ramakers, B.P.C.; Pickkers, P.; Deussen, A.; Rongen, G.A.P.J.M.; Broek, P. van den; Hoeven, J.G. van der; Smits, P.; Riksen, N.P.


    The endogenous nucleoside adenosine has profound tissue protective effects in situations of ischaemia or inflammation. Animal studies have shown that various drugs can activate this protective mechanism by interfering with the metabolism of adenosine. Translation of this concept to the clinical

  19. Engineering the intracellular metabolism of Escherichia coli to produce gamma-aminobutyric acid by co-localization of GABA shunt enzymes. (United States)

    Pham, Van Dung; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho


    To direct the carbon flux from Krebs cycle into the gamma-aminobutyric acid (GABA) shunt pathway for the production of GABA by protein scaffold introduction in Escherichia coli. Escherichia coli was engineered to produce GABA from glucose by the co-localization of enzymes succinate semialdehyde dehydrogenase (GadD), GABA aminotransferase (PuuE) and GABA transporter (GadC) by protein scaffold. 0.7 g GABA l(-1) was produced from 10 g glucose l(-1) while no GABA was produced in wild type E. coli. pH 6 and 30 °C were optimum for GABA production, and GABA concentration increased to 1.12 g GABA l(-1) when 20 g glucose l(-1) was used. When competing metabolic networks were inactivated, GABA increased by 24 % (0.87 g GABA l(-1)). The novel GABA production system was constructed by co-localization of GABA shunt enzymes.

  20. Modulation of Tonic GABA Currents by Anion Channel and Connexin Hemichannel Antagonists. (United States)

    Ransom, Christopher B; Ye, Zucheng; Spain, William J; Richerson, George B


    Anion channels and connexin hemichannels are permeable to amino acid neurotransmitters. It is hypothesized that these conductive pathways release GABA, thereby influencing ambient GABA levels and tonic GABAergic inhibition. To investigate this, we measured the effects of anion channel/hemichannel antagonists on tonic GABA currents of rat hippocampal neurons. In contrast to predictions, blockade of anion channels and hemichannels with NPPB potentiated tonic GABA currents of neurons in culture and acute hippocampal slices. In contrast, the anion channel/hemichannel antagonist carbenoxolone (CBX) inhibited tonic currents. These findings could result from alterations of ambient GABA concentration or direct effects on GABAA receptors. To test for effects on GABAA receptors, we measured currents evoked by exogenous GABA. Coapplication of NPPB with GABA potentiated GABA-evoked currents. CBX dose-dependently inhibited GABA-evoked currents. These results are consistent with direct effects of NPPB and CBX on GABAA receptors. GABA release from hippocampal cell cultures was directly measured using HPLC. Inhibition of anion channels with NPPB or CBX did not affect GABA release from cultured hippocampal neurons. NPPB reduced GABA release from pure astrocytic cultures by 21%, but the total GABA release from astrocytes was small compared to that of mixed cultures. These data indicate that drugs commonly used to antagonize anion channels and connexin hemichannels may affect tonic currents via direct effects on GABAA receptors and have negligible effects on ambient GABA concentrations. Interpretation of experiments using NPPB or CBX should include consideration of their effects on tonic GABA currents.

  1. Direct and indirect effects of cannabinoids on in vitro GABA release in the rat arcuate nucleus. (United States)

    Menzies, J R W; Ludwig, M; Leng, G


    Within the hypothalamic arcuate nucleus, two neuronal subpopulations play particularly important roles in energy balance; neurones expressing neuropeptide Y (NPY), agouti-related peptide (AgRP) and GABA are orexigenic, whereas neurones expressing pro-opiomelanocortin and CART are anorexigenic. The pivotal role of these neuropeptides in energy homeostasis is well-known, although GABA may also be an important signal because targeted knockout of the GABA transporter in NPY/AgRP/GABA neurones results in a lean, obesity-resistant phenotype. In the present study, we describe an in vitro model of K(+)-evoked GABA release from the hypothalamus and determine the effects of cannabinoid receptor activation. K(+)-evoked GABA release was sensitive to leptin, insulin and PYY(3-36), indicating that GABA was released by arcuate NPY/AgRP/GABA neurones. In the presence of tetrodotoxin (TTX), the cannabinoid CB1 receptor agonist WIN 55,212-2 inhibited K(+)-evoked GABA release. This was prevented by the CB1 receptor inverse agonist rimonabant. Rimonabant had no effect when applied alone. In the absence of TTX, however, the opposite effects were observed: WIN 55,212-2 had no effect while rimonabant inhibited GABA release. This indicates that GABA release can involve an indirect, TTX-sensitive mechanism. The most parsimonious explanation for the inhibition of GABA release by a CB receptor inverse agonist is via the disinhibition of an cannabinoid-sensitive inhibitory input onto GABAergic neurones. One local source of an inhibitory neurotransmitter is the opioidergic arcuate neurones. In our in vitro model, K(+)-evoked GABA release was inhibited by the endogenous opioid peptide beta-endorphin in a naloxone-sensitive manner. The inhibitory effect of rimonabant was also prevented by naloxone and a kappa-opioid receptor selective antagonist, suggesting that GABA release from arcuate NPY/AgRP/GABA neurones can be inhibited by endogenous opioid peptides, and that the release of opioid

  2. Positive social behaviours are induced and retained after oxytocin manipulations mimicking endogenous concentrations in a wild mammal. (United States)

    Robinson, Kelly J; Twiss, Sean D; Hazon, Neil; Moss, Simon; Pomeroy, Patrick P


    The neuropeptide hormone oxytocin modulates numerous social and parental behaviours across a wide range of species, including humans. We conducted manipulation experiments on wild grey seals ( Halichoerus grypus ) to determine whether oxytocin increases proximity-seeking behaviour, which has previously been correlated with endogenous oxytocin concentrations in wild seal populations. Pairs of seals that had never met previously were given intravenous injections of 0.41 µg kg -1 oxytocin or saline and were observed for 1 h post-manipulation. The dose was designed to mimic endogenous oxytocin concentrations during the observation period, and is one of the lowest doses used to manipulate behaviour to date. Seals given oxytocin spent significantly more time in close proximity to each other, confirming that oxytocin causes conspecifics to seek others out and remain close to one another. Aggressive and investigative behaviours also significantly fell after oxytocin manipulations. Despite using a minimal oxytocin dose, pro-social behavioural changes unexpectedly persisted for 2 days despite rapid dose clearance from circulation post-injection. This study verifies that oxytocin promotes individuals staying together, demonstrating how the hormone can form positive feedback loops of oxytocin release following conspecific stimuli, increased motivation to remain in close proximity and additional oxytocin release from stimuli received while in close proximity. © 2017 The Authors.

  3. A Steered Molecular Dynamics Study of Binding and Translocation Processes in the GABA Transporter

    DEFF Research Database (Denmark)

    Skovstrup, Soren; David, Laurent; Taboureau, Olivier


    The entire substrate translocation pathway in the human GABA transporter (GAT-1) was explored for the endogenous substrate GABA and the anti-convulsive drug tiagabine. Following a steered molecular dynamics (SMD) approach, in which a harmonic restraining potential is applied to the ligand...

  4. EFECTO DE LA ADMINISTRACIÓN INTRACEREBRAL DE MK-801 Y (- NICOTINA EN LAS CONCENTRACIONES EXTRACELULARES DE GLU Y GABA EN EL NÚCLEO PEDUNCULOPONTINO DE RATAS Effect of the Mk801 and (- Nicotine Intracerebral Administration on Glu and Gaba Extracellular Concentration in the Pedunculopontine Nucleus from Rats

    Directory of Open Access Journals (Sweden)


    Full Text Available Aunque la manipulación farmacológica de los sistemas glutamatérgico y colinérgico se ha tratado en modelos experimentales de enfermedad de Parkinson (EP, pocos autores han realizado estudios de esta temática a nivel del núcleo pedunculopontino (NPP. El presente trabajo aborda los cambios en las concentraciones extracelulares (CE de glutamato (Glu y ácido δ-amino butírico (GABA en el NPP de ratas hemiparkinsonizadas por inyección de 6-hidroxidopamina (6-OHDA y sometidas a infusión local de MK-801 (10 µmol/L o (- nicotina (10 mM. La infusión se realizó mediante microdiálisis cerebral y la determinación de CE de neurotransmisores se realizó a través de cromatografía líquida de alta resolución acoplada a detección de fluorescencia. La infusión de MK-801 en el NPP produjo disminución significativa de CE de Glu (pAlthough the pharmacological manipulation of the glutamatergic and cholinergic systems have been studied in animal models of Parkinson´s disease (PD, only some authors have done work on this topic at the pedunculopontine nucleus (PPN. The present work studied the changes in glutamate (Glu and δ-aminobutyric acid (GABA extracellular concentrations (EC in the PPN from hemiparkinsonian rats by 6hydroxydopamine injection. The rats were locally perfused by MK-801 (10 µmol/L or (- nicotine (10 mM solutions by cerebral microdyalisis. The biochemical studies were carried out through high performance liquid chromatography coupled to fluorescence detection. MK-801 infusion induced a significant decrease of Glu (p< 0.01 and GABA (p< 0.01 EC in PPN. On the other hand (- nicotine infusion induced a significant increase of Glu (p< 0.001 and GABA (p< 0.001 EC in PPN from hemiparkinsonian rats. The local blockade of NMDA receptors by MK-801 infusion facilitates the interaction between Glu and their metabotropic receptors that take part in presynaptic inhibition mechanisms and interfere with neurotransmitters release. Meanwhile, the

  5. Low nanomolar GABA effects at extrasynaptic a4ß1/ß3delta GABAA receptor subtypes indicate a different binding mode for GABA at these receptors

    DEFF Research Database (Denmark)

    Karim, Nasiara; Wellendorph, Petrine; Absalom, Nathan


    the two-electrode voltage clamp technique, and to investigate, using site-directed mutagenesis, the molecular determinants for GABA potency at a4ß3d GABA(A) receptors. a4/d-Containing GABA(A) receptors displayed high sensitivity to GABA, with mid-nanomolar concentrations activating a4ß1d (EC(50)=24n......M) and a4ß3d (EC(50)=12nM) receptors. In the majority of oocytes expressing a4ß3d subtypes, GABA produced a biphasic concentration-response curve, and activated the receptor with low and high concentrations (EC(50)(1)=16nM; EC(50)(2)=1.2µM). At a4ß2d, GABA had low micromolar activity (EC(50)=1µ...... did not significantly affect GABA potency. Mutating the residue R218 of the d-subunit, equivalent to the GABA binding residue R207 of the ß2-subunit, reduced the potency of GABA by 670-fold, suggesting a novel GABA binding site at the d-subunit interface. Taken together, GABA may have different...

  6. Plasma concentrations of asymmetric dimethylarginine, an endogenous nitric oxide synthase inhibitor, are elevated in sickle cell patients but do not increase further during painful crisis

    NARCIS (Netherlands)

    Landburg, Precious P.; Teerlink, Tom; Muskiet, Frits A. J.; Duits, Ashley J.; Schnog, John-John B.

    Plasma concentrations of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, are elevated in the clinically asymptomatic state of sickle cell disease (SCD). However, the role of ADMA during vaso-occlusive complications has not been defined. ADMA concentrations were

  7. Evaluation of plasma antioxidant activity in rats given excess EGCg with reference to endogenous antioxidants concentrations and assay methods. (United States)

    Yokotani, Kaori; Umegaki, Keizo


    The contribution of (-)-epigallocatechin gallate (EGCg) intake to in vivo antioxidant activity is unclear, even with respect to plasma. In this study, we examined how administration of EGCg contributes to plasma antioxidant activity, relative to its concentration, endogenous antioxidants, and assay methods, namely oxygen radical absorbance capacity (ORAC) and ferric reducing/antioxidant power (FRAP). Administration of EGCg (500 mg/kg) to rats increased plasma EGCg (4μmol/L as free form) and ascorbic acid (1.7-fold), as well as ORAC (1.2-fold) and FRAP (3-fold) values. The increase in plasma ascorbic acid following EGCg administration was accompanied by its relocation from the adrenal glands and lymphocytes into plasma, and was related to the increase in FRAP. Plasma deproteinization and assays in plasma model solutions revealed that protein levels significantly contributed to ORAC values, where antioxidant activity, as measured by both FRAP and ORAC. As the concentration of plasma ascorbic acid was not influenced by deproteinization, differences in FRAP values with and without deproteinization were estimated to determine the contribution of enhanced ascorbic acid attributable to EGCg administration. These results will help to understand the points that should be considered when evaluating EGCg antioxidant activity in plasma.

  8. Propionate enters GABAergic neurons, inhibits GABA transaminase, causes GABA accumulation and lethargy in a model of propionic acidemia. (United States)

    Morland, Cecilie; Frøland, Anne-Sofie; Pettersen, Mi Nyguyen; Storm-Mathisen, Jon; Gundersen, Vidar; Rise, Frode; Hassel, Bjørnar


    Propionic acidemia is the accumulation of propionate in blood due to dysfunction of propionyl-CoA carboxylase. The condition causes lethargy and striatal degeneration with motor impairment in humans. How propionate exerts its toxic effect is unclear. Here we show that intravenous administration of propionate causes dose-dependent propionate accumulation in the brain and transient lethargy in mice. Propionate, an inhibitor of histone deacetylase, entered GABAergic neurons, as could be seen from increased neuronal histone H4 acetylation in striatum and neocortex. Propionate caused an increase in GABA levels in the brain, suggesting inhibition of GABA breakdown. In vitro propionate inhibited GABA transaminase with a K i of ~1 mmol/L. In isolated nerve endings propionate caused increased release of GABA to the extracellular fluid. In vivo , propionate reduced cerebral glucose metabolism in both striatum and neocortex. We conclude that propionate-induced inhibition of GABA transaminase causes accumulation of GABA in the brain, leading to increased extracellular GABA concentration, which inhibits neuronal activity and causes lethargy. Propionate-mediated inhibition of neuronal GABA transaminase, an enzyme of the inner mitochondrial membrane, indicates entry of propionate into neuronal mitochondria. However, previous work has showed that neurons are unable to metabolize propionate oxidatively, leading us to conclude that propionyl-CoA synthetase is probably absent from neuronal mitochondria. Propionate-induced inhibition of energy metabolism in GABAergic neurons may render the striatum, in which >90% of the neurons are GABAergic, particularly vulnerable to degeneration in propionic acidemia. ©2018 The Author(s).

  9. Melatonin disrupts circadian rhythms of glutamate and GABA in the neostriatum of the aware rat: a microdialysis study. (United States)

    Marquez de Prado, B; Castañeda, T R; Galindo, A; del Arco, A; Segovia, G; Reiter, R J; Mora, F


    The purpose of this study was to investigate possible circadian changes in extracellular concentrations of glutamate (GLU) and gamma-aminobutyric acid (GABA). and the influence of melatonin on the levels of these neurotransmitters in the neostriatum of awake rats using in vivo microdialysis. At the same time, the concentrations of the amino acids taurine (TAU), glutamine (GLN) and arginine (ARG), as well as dopamine (DA) and its metabolites 3, 4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA), were measured in the extracellular fluid. When dialysates were collected over a 24-hr period (6 hr dark, 12 hr light, 6 hr dark), both GLU and GABA, without the infusion of melatonin, exhibited statistically significant rhythms, with higher levels of these constituents during the dark and lower levels during the day. Perfusion with melatonin (for 19 consecutive hours) prevented the daytime reductions in both GLU and GABA. Of the amino acids measured in the dialysates collected from the neostriatum of non-perfused rats, only ARG exhibited a significant change during the light:dark cycle; again, lowest concentrations were measured during the day. While melatonin perfusion did not statistically significantly influence neostriatal levels of TAU and ARG, GLN levels continued to drop during the infusion of the indoleamine. Dialysate concentrations of DA, DOPAC and HVA exhibited circadian rhythms which were not influenced by melatonin perfusion. The findings indicate there are differential effects of melatonin on extracellular neurotransmitter concentrations in the neostriatum of the awake rat. The results also suggest that the day:night variations in GLU and GABA may relate to daily changes in endogenous melatonin production, while DA and its metabolites are minimally influenced by this secretory product.

  10. In vivo imaging of estrogen receptor concentration in the endometrium and myometrium using FES PET - influence of menstrual cycle and endogenous estrogen level

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchida, Tatsuro [Department of Radiology, Faculty of Medical Sciences, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan)]. E-mail:; Okazawa, Hidehiko [Biomedical Imaging Research Center, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan); Mori, Tetsuya [Biomedical Imaging Research Center, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan); Kobayashi, Masato [Biomedical Imaging Research Center, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan); Yoshida, Yoshio [Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan); Fujibayashi, Yasuhisa [Biomedical Imaging Research Center, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan); Itoh, Harumi [Department of Radiology, Faculty of Medical Sciences, University of Fukui, Yoshida-gun, Fukui 910-1193 (Japan)


    Purpose: The goals of this study were to measure estrogen receptor (ER) concentration in the endometrium and myometrium using 16{alpha}-[{sup 18}F]fluoro-17{beta}-estradiol (FES) positron emission tomography (PET) and to investigate the relationship between changes in these parameters with the menstrual cycle and endogenous estrogen levels. Methods: Sixteen female healthy volunteers were included in this study. After blood sampling to measure endogenous estrogen level, FES PET image was acquired 60 min postinjection of FES. After whole-body imaging of FES PET, averaged standardized uptake values (SUVs) in the endometrium and myometrium were measured, and the relationship between FES uptake and menstrual cycle or endogenous estrogen level was evaluated. Results: Endometrial SUV was significantly higher in the proliferative phase than in the secretory phase (6.03{+-}1.05 vs. 3.97{+-}1.29, P=.022). In contrast, there was no significant difference in myometrial SUV when the proliferative and secretory phases were compared (P=.23). Further, there was no correlation between SUV and endogenous estrogen level in the proliferative phase. Conclusions: The change of ER concentration relative to menstrual cycle as characterized by FES PET was consistent with those from previous reports that used an immunohistochemical technique. These data suggest that FES PET is a feasible, noninvasive method for characterizing changes in ER concentration.

  11. Evidence for a Revised Ion/Substrate Coupling Stoichiometry of GABA Transporters. (United States)

    Willford, Samantha L; Anderson, Cynthia M; Spencer, Shelly R; Eskandari, Sepehr


    Plasma membrane γ-aminobutyric acid (GABA) transporters (GATs) are electrogenic transport proteins that couple the cotranslocation of Na(+), Cl(-), and GABA across the plasma membrane of neurons and glia. A fundamental property of the transporter that determines its ability to concentrate GABA in cells and, hence, regulate synaptic and extra-synaptic GABA concentrations, is the ion/substrate coupling stoichiometry. Here, we scrutinized the currently accepted 2 Na(+):1 Cl(-):1 GABA stoichiometry because it is inconsistent with the measured net charge translocated per co-substrate (Na(+), Cl(-), and GABA). We expressed GAT1 and GAT3 in Xenopus laevis oocytes and utilized thermodynamic and uptake under voltage-clamp measurements to determine the stoichiometry of the GABA transporters. Voltage-clamped GAT1-expressing oocytes were internally loaded with GABA, and the reversal potential (V rev) of the transporter-mediated current was recorded at different external concentrations of Na(+), Cl(-), or GABA. The shifts in V rev for a tenfold change in the external Na(+), Cl(-), and GABA concentration were 84 ± 4, 30 ± 1, and 29 ± 1 mV, respectively. To determine the net charge translocated per Na(+), Cl(-), and GABA, we measured substrate fluxes under voltage clamp in cells expressing GAT1 or GAT3. Charge flux to substrate flux ratios were 0.7 ± 0.1 charge/Na(+), 2.0 ± 0.2 charges/Cl(-), and 2.1 ± 0.1 charges/GABA. Altogether, our results strongly suggest a 3 Na(+):1 Cl(-):1 GABA coupling stoichiometry for the GABA transporters. The revised stoichiometry has important implications for understanding the contribution of GATs to GABAergic signaling in health and disease.

  12. Inherited disorders of GABA metabolism


    Pearl, Phillip L; Hartka, Thomas R; Cabalza, Jessica L; Taylor, Jacob; Gibson, Michael K


    The inherited disorders of γ-amino butyric acid (GABA) metabolism require an increased index of clinical suspicion. The known genetic disorders are GABA-transaminase deficiency, succinic semialdehyde dehydrogenase (SSADH) deficiency and homocarnosinosis. A recent link has also been made between impaired GABA synthesis and nonsyndromic cleft lip, with or without cleft palate. SSADH deficiency is the most commonly occurring of the inherited disorders of neurotransmitters. The disorder has a non...

  13. [GABA receptors: structure and functions]. (United States)

    Tiurenkov, I N; Perfilova, V N


    Data on the structure, localization, physiology, and pharmacology of GABA receptors are reviewed. These receptors belong to cis-loop receptors and consist of 16 subunits in various combinations and occur in both central nervous system and peripheral organs. There are a great number of their allosteric modulators, agonists and antagonists. Activation of GABA receptors is accompanied by changes in the permeability of plasmatic membranes for chloride ions, which is followed by depolarization (presynaptic inhibition) or hyperpolarization (postsynaptic inhibition). GABA receptors contain some topographically different binding sites, intended for the interaction both with the main mediator (GABA) and with allosteric regulators such as benzodiazepines, barbiturates, convulsants, ethanol, and neurosteroids.

  14. Effect of phosphatidylserine on the basal and GABA-activated Cl- permeation across single nerve membranes from rabbit Deiters' neurons

    Energy Technology Data Exchange (ETDEWEB)

    Rapallino, M.V.; Cupello, A.; Mainardi, P.; Besio, G.; Loeb, C.W. (Centro di Studio per la Neurofisiologia Cerebrale, C.N.R., Genova (Italy))


    The permeation of labeled Cl- ions across single plasma membranes from Deiters' neurons has been studied in the presence of various concentrations of phosphatidylserine (PS) on their extracellular side. PS reduces significantly basal Cl- permeation only at 10(-5) M on the membrane exterior. No effect was found at other concentrations. GABA activable 36Cl- permeation is heavily reduced and almost abolished at 10(-11) - 10(-5) M phosphatidylserine. This exogenous phosphatidylserine effect is difficult to interpret in relation to the function of the endogenous phospholipid. However, it may be involved in the epileptogenic effect in vivo of exogenous phosphatidylserine administration to rats.

  15. Quantitative evaluation of the therapeutic effect of fermented soybean products containing a high concentration of GABA on phthalic anhydride-induced atopic dermatitis in IL-4/Luc/CNS-1 Tg mice. (United States)

    Lee, Young Ju; Kim, Ji Eun; Kwak, Moon Hwa; Go, Jun; Kim, Dong Seob; Son, Hong Joo; Hwang, Dae Youn


    Cheonggukjang (CKJ) is a fermented soybean product that exhibits diverse biological and pharmacological activities, including anti-obesity, anti-diabetic, and anti-inflammatory effects on human chronic diseases. In this study, the effects of the aqueous extract of CKJ containing a high concentration of GABA on atopic dermatitis (AD) were quantified using the luciferase reporter system in IL-4/Luc/CNS-1 transgenic (Tg) mice. Alterations of the luciferase signal and phenotypes of AD were quantified in the IL-4/Luc/CNS-1 Tg mice co-treated with phthalic anhydride (PA) and CKJ for 4 weeks using the IVIS imaging system. A strong luciferase signal was detected in the abdominal region of IL-4/Luc/CNS-1 Tg mice treated with PA alone. However, this signal was significantly reduced in IL-4/Luc/CNS-1 Tg mice co-treated with PA and CKJ. The thymus showed the greatest decrease in luciferase following CKJ treatment, but the level increased after PA treatment. Furthermore, the CKJ-treated group showed improvement of common allergic responses including decreased ear thickness, dermis thickness, auricular lymph node (ALN) weight and infiltrating mast cells. However, IgE concentration and epidermis thickness were maintained a constant level. These results indicated that the luciferase signal may successfully reflect the therapeutic effects of CKJ in IL-4/Luc/CNS-1 Tg mice. The results also suggested that CKJ may be considered an effective substance for the treatment of AD.

  16. Segregation of acetylcholine and GABA in the rat superior cervical ganglia: functional correlation.

    Directory of Open Access Journals (Sweden)

    Diana eElinos


    Full Text Available Sympathetic neurons have the capability to segregate their neurotransmitters (NTs and co-transmitters to separate varicosities of single axons; furthermore, in culture, these neurons can even segregate classical transmitters. In vivo sympathetic neurons employ acetylcholine (ACh and other classical NTs such as gamma aminobutyric acid (GABA. Herein, we explore whether these neurons in vivo segregate these classical NTs in the superior cervical ganglia of the rat. We determined the topographical distribution of GABAergic varicosities, somatic GABAA receptor, as well as the regional distribution of the segregation of ACh and GABA. We evaluated possible regional differences in efficacy of ganglionic synaptic transmission, in the sensitivity of GABAA receptor to GABA and to the competitive antagonist picrotoxin (PTX. We found that sympathetic preganglionic neurons in vivo do segregate ACh and GABA. GABAergic varicosities and GABAA receptor expression showed a rostro-caudal gradient along ganglia; in contrast, segregation exhibited a caudo-rostral gradient. These uneven regional distributions in expression of GABA, GABAA receptors, and level segregation correlate with stronger synaptic transmission found in the caudal region. Accordingly, GABAA receptors of rostral region show larger sensitivity to GABA and PTX. These results suggest the presence of different types of GABAA receptors in each region that result in a different regional levels of endogenous GABA inhibition. Finally, we discuss a possible correlation of these different levels of GABA modulation and the function of the target organs innervated by rostral and caudal ganglionic neurons.

  17. Neurosteroids and GABA-A receptor function

    Directory of Open Access Journals (Sweden)

    Mingde eWang


    Full Text Available Neurosteroids represent a class of endogenous steroids that are synthesized in the brain, the adrenals and the gonads and have potent and selective effects on the GABAA-receptor. 3α-hydroxy A-ring reduced metabolites of progesterone, deoxycorticosterone and testosterone are positive modulators of GABAA-receptor in a non-genomic manner. Allopregnanolone (3α-OH-5α-pregnan-20-one, 5α-androstane-3α, 17α-diol (Adiol and 3α5α-tetrahydrodeoxy-corticosterone (3α5α-THDOC enhance the GABA mediated Cl− currents acting on a site (or sites distinct from the GABA, benzodiazepine, barbiturate and picrotoxin binding sites. 3α5α-P and 3α5α-THDOC potentiate synaptic GABAA-receptor function and activate delta-subunit containing extrasynaptic receptors that mediate tonic currents. On the contrary, 3β-OH pregnanesteroids and pregnenolone sulfate (PS are GABAA-receptor antagonists and induce activation-dependent inhibition of the receptor. The activities of neurosteroid are dependent on brain regions and types of neurons. In addition to the slow genomic action of the parent steroids, the non-genomic and rapid actions of neurosteroids play a significant role in the GABAA-receptor function and shift in mood and memory function. This review describes molecular mechanisms underlying neurosteroid action on the GABAA receptor, mood changes and cognitive functions.

  18. Reference ranges for urinary concentrations and ratios of endogenous steroids, which can be used as markers for steroid misuse, in a Caucasian population of athletes. (United States)

    Van Renterghem, Pieter; Van Eenoo, Peter; Geyer, Hans; Schänzer, Wilhelm; Delbeke, Frans T


    The detection of misuse with naturally occurring steroids is a great challenge for doping control laboratories. Intake of natural anabolic steroids alters the steroid profile. Thus, screening for exogenous use of these steroids can be established by monitoring a range of endogenous steroids, which constitute the steroid profile, and evaluate their concentrations and ratios against reference ranges. Elevated values of the steroid profile constitute an atypical finding after which a confirmatory IRMS procedure is needed to unequivocally establish the exogenous origin of a natural steroid. However, the large inter-individual differences in urinary steroid concentrations and the recent availability of a whole range of natural steroids (e.g. dehydroepiandrosterone and androstenedione) which each exert a different effect on the monitored parameters in doping control complicate the interpretation of the current steroid profile. The screening of an extended steroid profile can provide additional parameters to support the atypical findings and can give specific information upon the steroids which have been administered. The natural concentrations of 29 endogenous steroids and 11 ratios in a predominantly Caucasian population of athletes were determined. The upper reference values at 97.5%, 99% and 99.9% levels were assessed for male (n=2027) and female (n=1004) populations. Monitoring minor metabolites and evaluation of concentration ratios with respect to their natural abundances could improve the interpretation of the steroid profile in doping analysis. Copyright 2009 Elsevier Inc. All rights reserved.

  19. Neocortical GABA release at high intracellular sodium and low extracellular calcium: an anti-seizure mechanism. (United States)

    Rassner, Michael P; Moser, Andreas; Follo, Marie; Joseph, Kevin; van Velthoven-Wurster, Vera; Feuerstein, Thomas J


    In epilepsy, the GABA and glutamate balance may be disrupted and a transient decrease in extracellular calcium occurs before and during a seizure. Flow Cytometry based fluorescence activated particle sorting experiments quantified synaptosomes from human neocortical tissue, from both epileptic and non-epileptic patients (27.7% vs. 36.9% GABAergic synaptosomes, respectively). Transporter-mediated release of GABA in human and rat neocortical synaptosomes was measured using the superfusion technique for the measurement of endogenous GABA. GABA release was evoked by either a sodium channel activator or a sodium/potassium-ATPase inhibitor when exocytosis was possible or prevented, and when the sodium/calcium exchanger was active or inhibited. The transporter-mediated release of GABA is because of elevated intracellular sodium. A reduction in the extracellular calcium increased this release (in both non-epileptic and epileptic, except Rasmussen encephalitis, synaptosomes). The inverse was seen during calcium doubling. In humans, GABA release was not affected by exocytosis inhibition, that is, it was solely transporter-mediated. However, in rat synaptosomes, an increase in GABA release at zero calcium was only exhibited when the exocytosis was prevented. The absence of calcium amplified the sodium/calcium exchanger activity, leading to elevated intracellular sodium, which, together with the stimulation-evoked intracellular sodium increment, enhanced GABA transporter reversal. Sodium/calcium exchange inhibitors diminished GABA release. Thus, an important seizure-induced extracellular calcium reduction might trigger a transporter- and sodium/calcium exchanger-related anti-seizure mechanism by augmenting transporter-mediated GABA release, a mechanism absent in rats. Uniquely, the additional increase in GABA release because of calcium-withdrawal dwindled during the course of illness in Rasmussen encephalitis. Seizures cause high Na(+) influx through action potentials. A

  20. Neocortical hyperexcitability after GABA withdrawal in vitro. (United States)

    Calixto, E; López-Colomé, A M; Casasola, C; Montiel, T; Bargas, J; Brailowsky, S


    The sharp interruption of the intracortical instillation of exogenous gamma-aminobutyric acid (GABA), generates an epileptic focus in mammals. Seizures elicited by GABA withdrawal last several days or weeks. The present work reports that GABA withdrawal-induced hyperexcitability can be produced in vitro: a sudden withdrawal of GABA (5 mM; 120 min) or benzodiazepine (60 microM flunitrazepam) from the superfusion, induced a gradual increase in the amplitude of the evoked population spike (PS) recorded on neocortical slices. PS enhancement reached 150% above the control value 2.5 h after GABA withdrawal. GABA withdrawal-induced hyperexcitability was facilitated by progesterone. PS enhancement induced by GABA withdrawal was associated with an impairment of GABA transmission occurring before epileptiform discharges were fully established. Paired pulse inhibition and evoked [3H]-GABA release appear decreased; suggesting that cortical hyperexcitability as a result of GABA withdrawal involves pre-synaptic changes. Specific muscimol binding decreased during GABA superfusion but recovered after GABA withdrawal. However, the sensitivity of the post-synaptic response to 3alpha-OH-5alpha-pregnan-20-one or allopregnanolone (alloP) was enhanced after GABA withdrawal, suggesting a functional change in the GABA(A) receptors. The changes described may be the cellular correlates of the withdrawal syndromes appearing after interruption of the administration of GABA(A) receptor agonists.

  1. Glutamate modulation of GABA transport in retinal horizontal cells of the skate (United States)

    Kreitzer, Matthew A; Andersen, Kristen A; Malchow, Robert Paul


    Transport of the amino acid GABA into neurons and glia plays a key role in regulating the effects of GABA in the vertebrate retina. We have examined the modulation of GABA-elicited transport currents of retinal horizontal cells by glutamate, the likely neurotransmitter of vertebrate photoreceptors. Enzymatically isolated external horizontal cells of skate were examined using whole-cell voltage-clamp techniques. GABA (1 mm) elicited an inward current that was completely suppressed by the GABA transport inhibitors tiagabine (10 μm) and SKF89976-A (100 μm), but was unaffected by 100 μm picrotoxin. Prior application of 100 μm glutamate significantly reduced the GABA-elicited current. Glutamate depressed the GABA dose-response curve without shifting the curve laterally or altering the voltage dependence of the current. The ionotropic glutamate receptor agonists kainate and AMPA also reduced the GABA-elicited current, and the effects of glutamate and kainate were abolished by the ionotropic glutamate receptor antagonist 6-cyano-7-nitroquinoxaline. NMDA neither elicited a current nor modified the GABA-induced current, and metabotropic glutamate analogues were also without effect. Inhibition of the GABA-elicited current by glutamate and kainate was reduced when extracellular calcium was removed and when recording pipettes contained high concentrations of the calcium chelator BAPTA. Caffeine (5 mm) and thapsigargin (2 nm), agents known to alter intracellular calcium levels, also reduced the GABA-elicited current, but increases in calcium induced by depolarization alone did not. Our data suggest that glutamate regulates GABA transport in retinal horizontal cells through a calcium-dependent process, and imply a close physical relationship between calcium-permeable glutamate receptors and GABA transporters in these cells. PMID:12562999

  2. Fast detection of extrasynaptic GABA with a whole-cell sniffer

    DEFF Research Database (Denmark)

    Christensen, Rasmus K; Petersen, Anders V; Schmitt, Nicole


    Gamma-amino-butyric acid (GABA) is the main inhibitory transmitter of the brain. It operates by binding to specific receptors located both inside and outside synapses. The extrasynaptic receptors are activated by spillover from GABAergic synapses and by ambient GABA in the extracellular space...... and temporal resolution. We used a human embryonic kidney (HEK) cell line that stably expresses GABAA receptors composed of α1, β2, and γ2 subunits. We recorded from such a HEK cell with the whole-cell patch-clamp technique. The presence of GABA near the HEK cell generated a measurable electric current whose......, the sniffer detects variations in the extrasynaptic GABA concentration with millisecond time resolution. Pilot experiments demonstrate that the sniffer is able to report spillover of GABA induced by synaptic activation in real time. This is the first report on a GABA sensor that combines the ability to detect...

  3. Beta-hydroxybutyrate alters GABA-transaminase activity in cultured astrocytes. (United States)

    Suzuki, Yuka; Takahashi, Hisaaki; Fukuda, Mitsumasa; Hino, Hitomi; Kobayashi, Kana; Tanaka, Junya; Ishii, Eiichi


    The ketogenic diet has long been recognized as an effective treatment for medically refractory epilepsy. Despite nearly a century of use, the mechanisms underlying its clinical efficacy remain unknown. One of the proposed hypotheses for its anti-epileptic actions involves increased GABA concentration in the brain due to ketone bodies that become elevated with a ketogenic diet. In recent years, the notion that astrocytes could play a role in the evolution of abnormal cortical excitability in chronic neurological disorders, such as epilepsy, has received renewed attention. The present study examined the effects of beta-hydroxybutyrate, a ketone body, on GABA metabolism in rat primary cultured astrocytes. When beta-hydroxybutyrate was added to culture medium, GABA-transaminase (GABA-T) mRNA expression was significantly suppressed in time- and dose-dependent manners. GABA-T enzymatic activity in beta-hydroxybutyrate-treated astrocytes was also suppressed, in accordance with its gene expression. These effects were evident after 3 days of culture, which might coincide with depleted intracellular glycogen. GABA transporter, GAT-1, gene expression was strongly suppressed in cultured astrocytes after 5 days of culture with beta-hydroxybutyrate, although other type of GABA transporters did not display significant changes. These results suggest that beta-hydroxybutyrate induced by ketogenic diet may increase GABA concentration in the epileptic brain by suppressing astrocytic GABA degradation, leading to antiepileptic effects.

  4. [Endogenous hypertriglyceridemia]. (United States)

    Tsukamoto, Kazuhisa


    Endogenous hypertriglyceridemia, which includes familial hypertriglyceridemia and idiopathic hypertriglyceridemia, is characterized by the increased level of VLDL-triglycerides in the blood. Increased production of VLDL from the liver and the decreased catabolism of VLDL-TG in the vessel, which are also the main metabolic features of insulin resistance, have been proposed to be the causes of endogenous hypertriglyceridemia. Genetic factors responsible for endogenous hypertriglyceridemia have been elucidated in several studies, however, these factors have so far not been clearly identified yet; thus the causes of endogenous hypertriglyceridemia would be polygenic. Recent advances in the genetic analytical methods like genome-wide association study would hopefully unveil the whole pictures of endogenous hypertriglyceridemia.

  5. An analysis of concentration of sucrose, endogenous pH, and alteration in the plaque pH on consumption of commonly used liquid pediatric medicines

    Directory of Open Access Journals (Sweden)

    Sunitha S


    Full Text Available Background: Many parents are often unaware of the hidden, added sugars in many foods and drinks including pediatric liquid medicines; thus, hidden sugar in the form of pediatric medications has not been focused upon as cariogenic agents. Objective: (i assess concentration of sucrose in six pediatric drugs, (ii determine endogenous pH of these drugs, and (iii estimate drop in the plaque pH in the oral cavity in first 30 minutes after consumption of the drugs. Materials and Methods: Ten adult volunteers with mean age of 22 years were double blinded for the study. Concentration of sucrose was assessed by volumetric method at Department of Chemical Branch of Engineering. Endogenous pH and drop in the plaque pH after consumption of the drugs were assessed using digital pH meter. Statistical analysis: SPSS software was used to assess the pH level at different time intervals and expressed as mean ± SD. Changes in pH were assessed by one-way ANOVA followed by Wilcoxons signed rank test. P-value was set at 0.05. Result: There were varying amounts of fermentable sucrose detected in the drugs; all the drugs were acidic. There is a significant drop of plaque pH after consumption of the drug. Conclusion: These sweeteners along with their low endogenic pH form a high cariogenic formulation. Thus, nonsucrose (noncariogenic or sugar-free medications are needed to be prescribed along with proper oral hygiene care to the children under medication.

  6. Functional properties of GABA synaptic inputs onto GABA neurons in monkey prefrontal cortex

    NARCIS (Netherlands)

    D.C. Rotaru (Diana C.); C. Olezene (Cameron); T. Miyamae (Takeaki); N.V. Povysheva (Nadezhda V.); A.V. Zaitsev (Aleksey V.); D.A. Lewis (David A.); G. Gonzalez-Burgos (Guillermo)


    textabstractIn rodent cortex GABAA receptor (GABAAR)-mediated synapses are a significant source of input onto GABA neurons, and the properties of these inputs vary among GABA neuron subtypes that differ in molecular markers and firing patterns. Some features of cortical

  7. Actions of insecticides on the insect GABA receptor complex

    Energy Technology Data Exchange (ETDEWEB)

    Bermudez, I.; Hawkins, C.A.; Taylor, A.M.; Beadle, D.J. (School of Biological and Molecular Sciences, Oxford Polytechnic, Headington, Oxford (England))


    The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using (35S)t-butylbicyclophosphorothionate (( 35S)TBPS) binding and voltage-clamp techniques. Specific binding of (35S)TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 {plus minus} 2.9 nM and a Bmax value of 1770 {plus minus} 40 fmol/mg protein. (35S)TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of (35S)TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on (35S)TBPS binding. These results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current.

  8. Identification of the sites for CaMK-II-dependent phosphorylation of GABA(A) receptors. (United States)

    Houston, Catriona M; Lee, Henry H C; Hosie, Alastair M; Moss, Stephen J; Smart, Trevor G


    Phosphorylation can affect both the function and trafficking of GABA(A) receptors with significant consequences for neuronal excitability. Serine/threonine kinases can phosphorylate the intracellular loops between M3-4 of GABA(A) receptor beta and gamma subunits thereby modulating receptor function in heterologous expression systems and in neurons (1, 2). Specifically, CaMK-II has been demonstrated to phosphorylate the M3-4 loop of GABA(A) receptor subunits expressed as GST fusion proteins (3, 4). It also increases the amplitude of GABA(A) receptor-mediated currents in a number of neuronal cell types (5-7). To identify which substrate sites CaMK-II might phosphorylate and the consequent functional effects, we expressed recombinant GABA(A) receptors in NG108-15 cells, which have previously been shown to support CaMK-II modulation of GABA(A) receptors containing the beta3 subunit (8). We now demonstrate that CaMK-II mediates its effects on alpha1beta3 receptors via phosphorylation of Ser(383) within the M3-4 domain of the beta subunit. Ablation of beta3 subunit phosphorylation sites for CaMK-II revealed that for alphabetagamma receptors, CaMK-II has a residual effect on GABA currents that is not mediated by previously identified sites of CaMK-II phosphorylation. This residual effect is abolished by mutation of tyrosine phosphorylation sites, Tyr(365) and Tyr(367), on the gamma2S subunit, and by the tyrosine kinase inhibitor genistein. These results suggested that CaMK-II is capable of directly phosphorylating GABA(A) receptors and activating endogenous tyrosine kinases to phosphorylate the gamma2 subunit in NG108-15 cells. These findings were confirmed in a neuronal environment by expressing recombinant GABA(A) receptors in cerebellar granule neurons.

  9. Insulin reduces neuronal excitability by turning on GABA(A channels that generate tonic current.

    Directory of Open Access Journals (Sweden)

    Zhe Jin

    Full Text Available Insulin signaling to the brain is important not only for metabolic homeostasis but also for higher brain functions such as cognition. GABA (γ-aminobutyric acid decreases neuronal excitability by activating GABA(A channels that generate phasic and tonic currents. The level of tonic inhibition in neurons varies. In the hippocampus, interneurons and dentate gyrus granule cells normally have significant tonic currents under basal conditions in contrast to the CA1 pyramidal neurons where it is minimal. Here we show in acute rat hippocampal slices that insulin (1 nM "turns on" new extrasynaptic GABA(A channels in CA1 pyramidal neurons resulting in decreased frequency of action potential firing. The channels are activated by more than million times lower GABA concentrations than synaptic channels, generate tonic currents and show outward rectification. The single-channel current amplitude is related to the GABA concentration resulting in a single-channel GABA affinity (EC(50 in intact CA1 neurons of 17 pM with the maximal current amplitude reached with 1 nM GABA. They are inhibited by GABA(A antagonists but have novel pharmacology as the benzodiazepine flumazenil and zolpidem are inverse agonists. The results show that tonic rather than synaptic conductances regulate basal neuronal excitability when significant tonic conductance is expressed and demonstrate an unexpected hormonal control of the inhibitory channel subtypes and excitability of hippocampal neurons. The insulin-induced new channels provide a specific target for rescuing cognition in health and disease.

  10. Anterior insula GABA levels correlate with emotional aspects of empathy: a proton magnetic resonance spectroscopy study.

    Directory of Open Access Journals (Sweden)

    Qianfeng Wang

    Full Text Available Empathy is a multidimensional construct referring to the capacity to understand and share the emotional and affective states of another person. Cerebral γ-aminobutyric acid (GABA-ergic levels are associated with a variety of neurological and psychiatric disorders. However, the role of the GABA system in different dimensions of empathy has not been investigated.Thirty-two right-handed healthy volunteers took part in this study. We used proton magnetic resonance spectroscopy to determine GABA concentrations in the anterior insula (AI and the anterior cingulate cortex (ACC and to examine the relationship between the GABA concentrations and the subcomponents of empathy evaluated by the Interpersonal Reactivity Index (IRI.Pearson correlation analyses (two-tailed showed that AI GABA was significantly associated with the empathy concern score (r = 0.584, p<0.05 and the personal distress score (r = 0.538, p<0.05 but not significantly associated with other empathy subscales. No significant correlation was found between ACC GABA and empathy subscores.Left AI GABA was positively correlated with the emotional aspects of empathy. These preliminary findings call into question whether AI GABA alterations might predict empathy dysfunction in major psychiatric disorders such as autism and schizophrenia, which have been described as deficits in emotional empathic abilities.

  11. GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies. (United States)

    Chiapponi, Chiara; Piras, Federica; Piras, Fabrizio; Caltagirone, Carlo; Spalletta, Gianfranco


    Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional-biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA MRS

  12. GABA system in schizophrenia and mood disorders. A mini review on third generation imaging studies

    Directory of Open Access Journals (Sweden)

    Chiara eChiapponi


    Full Text Available Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ, bipolar disorder (BD and major depressive disorder (MDD. We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis.In SZ unimodal studies gave mixed results, as increased, decreased or unaltered GABA levels were reported depending on region, disease phase and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients, mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signalling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ.Unimodal studies in BD revealed, again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls, nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate and N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology.Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy and functional-biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving

  13. The glutamate/GABA-glutamine cycle

    DEFF Research Database (Denmark)

    Bak, Lasse K; Schousboe, Arne; Waagepetersen, Helle S


    Neurons are metabolically handicapped in the sense that they are not able to perform de novo synthesis of neurotransmitter glutamate and gamma-aminobutyric acid (GABA) from glucose. A metabolite shuttle known as the glutamate/GABA-glutamine cycle describes the release of neurotransmitter glutamate...... or GABA from neurons and subsequent uptake into astrocytes. In return, astrocytes release glutamine to be taken up into neurons for use as neurotransmitter precursor. In this review, the basic properties of the glutamate/GABA-glutamine cycle will be discussed, including aspects of transport and metabolism....... Discussions of stoichiometry, the relative role of glutamate vs. GABA and pathological conditions affecting the glutamate/GABA-glutamine cycling are presented. Furthermore, a section is devoted to the accompanying ammonia homeostasis of the glutamate/GABA-glutamine cycle, examining the possible means...

  14. Extrasynaptic Release of GABA by Retinal Dopaminergic Neurons (United States)

    Hirasawa, Hajime; Puopolo, Michelino; Raviola, Elio


    GABA release by dopaminergic amacrine (DA) cells of the mouse retina was detected by measuring Cl− currents generated by isolated perikarya in response to their own neurotransmitter. The possibility that the Cl− currents were caused by GABA release from synaptic endings that had survived the dissociation of the retina was ruled out by examining confocal Z series of the surface of dissociated tyrosine hydroxylase-positive perikarya after staining with antibodies to preand postsynaptic markers. GABA release was caused by exocytosis because 1) the current events were transient on the millisecond time scale and thus resembled miniature synaptic currents; 2) they were abolished by treatment with a blocker of the vesicular proton pump, bafilomycin A1; and 3) their frequency was controlled by the intracellular Ca2+ concentration. Because DA cell perikarya do not contain presynaptic active zones, release was by necessity extrasynaptic. A range of depolarizing stimuli caused GABA exocytosis, showing that extrasynaptic release of GABA is controlled by DA cell electrical activity. With all modalities of stimulation, including long-lasting square pulses, segments of pacemaker activity delivered by the action-potential-clamp method and high-frequency trains of ramps, discharge of GABAergic currents exhibited considerable variability in latency and duration, suggesting that coupling between Ca2+ influx and transmitter exocytosis is extremely loose in comparison with the synapse. Paracrine signaling based on extrasynaptic release of GABA by DA cells and other GABAergic amacrines may participate in controlling the excitability of the neuronal processes that interact synaptically in the inner plexiform layer. PMID:19403749

  15. Anion transport and GABA signaling

    Directory of Open Access Journals (Sweden)

    Christian Andreas Huebner


    Full Text Available Whereas activation of GABAA receptors by GABA usually results in a hyperpolarizing influx of chloride into the neuron, the reversed chloride driving force in the immature nervous system results in a depolarizing efflux of chloride. This GABAergic depolarization is deemed to be important for the maturation of the neuronal network. The concept of a developmental GABA switch has mainly been derived from in vitro experiments and reliable in vivo evidence is still missing. As GABAA receptors are permeable for both chloride and bicarbonate, the net effect of GABA also critically depends on the distribution of bicarbonate. Whereas chloride can either mediate depolarizing or hyperpolarizing currents, bicarbonate invariably mediates a depolarizing current under physiological conditions. Intracellular bicarbonate is quickly replenished by cytosolic carbonic anhydrases. Intracellular bicarbonate levels also depend on different bicarbonate transporters expressed by neurons. The expression of these proteins is not only developmentally regulated but also differs between cell types and even subcellular regions. In this review we will summarize current knowledge about the role of some of these transporters for brain development and brain function.

  16. GABA Shunt in Durum Wheat

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    Petronia Carillo


    Full Text Available Plant responses to salinity are complex, especially when combined with other stresses, and involve many changes in gene expression and metabolic fluxes. Until now, plant stress studies have been mainly dealt only with a single stress approach. However, plants exposed to multiple stresses at the same time, a combinatorial approach reflecting real-world scenarios, show tailored responses completely different from the response to the individual stresses, due to the stress-related plasticity of plant genome and to specific metabolic modifications. In this view, recently it has been found that γ-aminobutyric acid (GABA but not glycine betaine (GB is accumulated in durum wheat plants under salinity only when it is combined with high nitrate and high light. In these conditions, plants show lower reactive oxygen species levels and higher photosynthetic efficiency than plants under salinity at low light. This is certainly relevant because the most of drought or salinity studies performed on cereal seedlings have been done in growth chambers under controlled culture conditions and artificial lighting set at low light. However, it is very difficult to interpret these data. To unravel the reason of GABA accumulation and its possible mode of action, in this review, all possible roles for GABA shunt under stress are considered, and an additional mechanism of action triggered by salinity and high light suggested.

  17. Hypoxia treatment on germinating faba bean (Vicia faba L. seeds enhances GABA-related protection against salt stress

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    Runqiang Yang


    Full Text Available The γ-aminobutyric acid (GABA is a non-protein amino acid with some functional properties for human health. Its content is usually lower in plant seeds. Hypoxia or salt (NaCl stress is an effective way for accumulating GABA during seed germination. However, NaCl stress on GABA accumulation under hypoxia is currently infrequent. The effect of NaCl on GABA accumulation in germinating faba bean (Vicia faba L. under hypoxia was therefore investigated in this study. Faba bean seeds were steeped in citric acid buffer (pH 3.5 containing NaCl with a final O2 concentration of 5.5 mg L-1 and germinated for 5 d. Results showed that 60 mmol L-1 NaCl was the optimum concentration for GABA accumulation in germinating faba beans under hypoxia. Germination for 5 d under hypoxia-NaCl stress was less beneficial for GABA accumulation than only hypoxia (control. Polyamine degradation pathway played a more important role for accumulating GABA in germinating faba bean as an adaptive response to NaCl stress. Removing NaCl significantly increased GABA content, while it decreased glutamate decarboxylase (GAD activity. Simultaneously, polyamine was accumulated, which might be related to the enhancement of physiological activity after recovery. When treated with aminoguanidine (AG for 3 d, GABA content decreased by 29.82%. These results indicated that the tolerance ability of GABA shunt to NaCl stress was weaker than that of polyamine degradation pathway. The NaCl treatment for 3 d under hypoxia could raise the contribution ratio of polyamine degradation pathway for GABA accumulation. The contribution ratio of polyamine degradation pathway for GABA formation was 29.82% when treated for at least 3 d

  18. Structures of gamma-aminobutyric acid (GABA) aminotransferase, a pyridoxal 5'-phosphate, and [2Fe-2S] cluster-containing enzyme, complexed with gamma-ethynyl-GABA and with the antiepilepsy drug vigabatrin. (United States)

    Storici, Paola; De Biase, Daniela; Bossa, Francesco; Bruno, Stefano; Mozzarelli, Andrea; Peneff, Caroline; Silverman, Richard B; Schirmer, Tilman


    Gamma-aminobutyric acid aminotransferase (GABA-AT) is a pyridoxal 5'-phosphate-dependent enzyme responsible for the degradation of the inhibitory neurotransmitter GABA. GABA-AT is a validated target for antiepilepsy drugs because its selective inhibition raises GABA concentrations in brain. The antiepilepsy drug, gamma-vinyl-GABA (vigabatrin) has been investigated in the past by various biochemical methods and resulted in several proposals for its mechanisms of inactivation. In this study we solved and compared the crystal structures of pig liver GABA-AT in its native form (to 2.3-A resolution) and in complex with vigabatrin as well as with the close analogue gamma-ethynyl-GABA (to 2.3 and 2.8 A, respectively). Both inactivators form a covalent ternary adduct with the active site Lys-329 and the pyridoxal 5'-phosphate (PLP) cofactor. The crystal structures provide direct support for specific inactivation mechanisms proposed earlier on the basis of radio-labeling experiments. The reactivity of GABA-AT crystals with the two GABA analogues was also investigated by polarized absorption microspectrophotometry. The spectral data are discussed in relation to the proposed mechanism. Intriguingly, all three structures revealed a [2Fe-2S] cluster of yet unknown function at the center of the dimeric molecule in the vicinity of the PLP cofactors.

  19. Modulation of GABA-stimulated chloride influx into membrane vesicles from rat cerebral cortex by triazolobenzodiazepines

    Energy Technology Data Exchange (ETDEWEB)

    Obata, T.; Yamamura, H.I.


    The effects of triazolobenzodiazepines of GABA-stimulated /sup 36/Cl/sup -/ uptake by membrane vesicles from rat cerebral cortex were examined. Triazolam and alprazolam showed a significant enhancement of GABA-stimulated /sup 36/Cl/sup -/ uptake at 0.01-10 uM. On the other hand, adinazolam showed a small enhancement at 0.1-1 uM followed by a significant inhibition of GABA-stimulated /sup 36/Cl/sup -/ uptake at 100 uM. The enhancement of GABA-stimulated /sup 36/Cl/sup -/ uptake by 1 uM alprazolam was antagonized by Ro15-1788, a benzodiazepine antagonist, but the inhibition of this response by 30 uM adinazolam was not antagonized by Ro15-1788. These results indicate that triazolobenzodiazepines enhanced GABA-stimulated /sup 36/Cl/sup -/ uptake through benzodiazepine receptors. High concentrations of adinazolam inhibit GABA-stimulated /sup 36/Cl/sup -/ uptake which may be due to the direct blockade of GABA-gated chloride channel. 23 references, 4 figures.

  20. Caenorhabditis elegans neuromuscular junction: GABA receptors and ivermectin action.

    Directory of Open Access Journals (Sweden)

    Guillermina Hernando

    Full Text Available The prevalence of human and animal helminth infections remains staggeringly high, thus urging the need for concerted efforts towards this area of research. GABA receptors, encoded by the unc-49 gene, mediate body muscle inhibition in Caenorhabditis elegans and parasitic nematodes and are targets of anthelmintic drugs. Thus, the characterization of nematode GABA receptors provides a foundation for rational anti-parasitic drug design. We therefore explored UNC-49 channels from C. elegans muscle cultured cells of the first larval stage at the electrophysiological and behavioral levels. Whole-cell recordings reveal that GABA, muscimol and the anthelmintic piperazine elicit macroscopic currents from UNC-49 receptors that decay in their sustained presence, indicating full desensitization. Single-channel recordings show that all drugs elicit openings of ∼2.5 pA (+100 mV, which appear either as brief isolated events or in short bursts. The comparison of the lowest concentration required for detectable channel opening, the frequency of openings and the amplitude of macroscopic currents suggest that piperazine is the least efficacious of the three drugs. Macroscopic and single-channel GABA-activated currents are profoundly and apparently irreversibly inhibited by ivermectin. To gain further insight into ivermectin action at C. elegans muscle, we analyzed its effect on single-channel activity of the levamisol-sensitive nicotinic receptor (L-AChR, the excitatory receptor involved in neuromuscular transmission. Ivermectin produces a profound inhibition of the frequency of channel opening without significant changes in channel properties. By revealing that ivermectin inhibits C. elegans muscle GABA and L-AChR receptors, our study adds two receptors to the already known ivermectin targets, thus contributing to the elucidation of its pleiotropic effects. Behavioral assays in worms show that ivermectin potentiates piperazine-induced paralysis, thus suggesting

  1. Purification of gamma-amino butyric acid (GABA) from fermentation of defatted rice bran extract by using ion exchange resin (United States)

    Tuan Nha, Vi; Phung, Le Thi Kim; Dat, Lai Quoc


    Rice bran is one of the significant byproducts of rice processing with 10 %w/w of constitution of whole rice grain. It is rich in nutrient compounds, including glutamic acid. Thus, it could be utilized for the fermentation with Lactobateria for synthesis of GABA, a valuable bioactive for antihypertensive effects. However, the concentration and purity of GABA in fermentation broth of defatted rice bran extract is low for production of GABA drug. This research focused on the purification of GABA from the fermentation broth of defatted rice bran extract by using cation exchange resin. The results indicate that, the adsorption isotherm of GABA by Purelite C100 showed the good agreement with Freundlich model, with high adsorption capacity. The effects of pH and concentration of NaCl in eluent on the elution were also investigated. The obtained results show that, at the operating conditions of elution as follows: pH 6.5, 0.8 M of NaCl in eluent, 0.43 of bed volume; concentration of GABA in accumulative eluent, the purity and recovery yield of GABA were 743.8 ppm, 44.0% and 84.2%, respectively. Results imply that, it is feasible to apply cation exchange resin for purification of GABA from fermentation broth of defatted rice bran extract.

  2. 5-(N, N-Hexamethylene) amiloride is a GABA-A ρ1 receptor positive allosteric modulator. (United States)

    Snell, Heather D; Gonzales, Eric B


    Guanidine compounds act as ion channel modulators. In the case of Cys-loop receptors, the guanidine compound amiloride antagonized the heteromeric GABA-A, glycine, and nicotinic acetylcholine receptors. However, amiloride exhibits characteristics consistent with a positive allosteric modulator for the human GABA-A (hGABA-A) ρ1 receptor. Site-directed mutagenesis revealed that the positive allosteric modulation was influenced by the GABA-A ρ1 second transmembrane domain 15' position, a site implicated in ligand allosteric modulation of Cys-loop receptors. There are a variety of amiloride derivatives that provide opportunities to assess the significance of amiloride functional groups (e.g., the guanidine group, the pyrazine ring, etc.) in the modulation of the GABA-A ρ1 receptor activity. We utilized 3 amiloride derivatives (benzamil, phenamil, and 5-(N, N-Hexamethylene) amiloride) to assess the contribution of these groups toward the potentiation of the GABA-A ρ1 receptor. Benzamil and phenamil failed to potentiate on the wild type GABA-A ρ1 GABA-mediated current while HMA demonstrated efficacy only at the highest concentration studied. The hGABA-A ρ1 (I15'N) mutant receptor activity was potentiated by lower HMA concentrations compared to the wild type receptor. Our findings suggest that an exposed guanidine group on amiloride and amiloride derivatives is critical for modulating the GABA-A ρ1 receptor. The present study provides a conceptual framework for predicting which amiloride derivatives will demonstrate positive allosteric modulation of the GABA-A ρ1 receptor.

  3. Synthesis of nylon 4 from gamma-aminobutyrate (GABA) produced by recombinant Escherichia coli. (United States)

    Park, Si Jae; Kim, Eun Young; Noh, Won; Oh, Young Hoon; Kim, Hye Young; Song, Bong Keun; Cho, Kwang Myung; Hong, Soon Ho; Lee, Seung Hwan; Jegal, Jonggeon


    In this study, we developed recombinant Escherichia coli strains expressing Lactococcus lactis subsp. lactis Il1403 glutamate decarboxylase (GadB) for the production of GABA from glutamate monosodium salt (MSG). Syntheses of GABA from MSG were examined by employing recombinant E. coli XL1-Blue as a whole cell biocatalyst in buffer solution. By increasing the concentration of E. coli XL1-Blue expressing GadB from the OD₆₀₀ of 2-10, the concentration and conversion yield of GABA produced from 10 g/L of MSG could be increased from 4.3 to 4.8 g/L and from 70 to 78 %, respectively. Furthermore, E. coli XL1-Blue expressing GadB highly concentrated to the OD₆₀₀ of 100 produced 76.2 g/L of GABA from 200 g/L of MSG with 62.4 % of GABA yield. Finally, nylon 4 could be synthesized by the bulk polymerization using 2-pyrrolidone that was prepared from microbially synthesized GABA by the reaction with Al₂O₃ as catalyst in toluene with the yield of 96 %.

  4. GABA systems, benzodiazepines, and substance dependence. (United States)

    Malcolm, Robert J


    Alterations in the gamma-aminobutyric acid (GABA) receptor complex and GABA neurotransmission influence the reinforcing and intoxicating effects of alcohol and benzodiazepines. Chronic modulation of the GABA(A)-benzodiazepine receptor complex plays a major role in central nervous system dysregulation during alcohol abstinence. Withdrawal symptoms stem in part from a decreased GABAergic inhibitory function and an increase in glutamatergic excitatory function. GABA(A) receptors play a role in both reward and withdrawal phenomena from alcohol and sedative-hypnotics. Although less well understood, GABA(B) receptor complexes appear to play a role in inhibition of motivation and diminish relapse potential to reinforcing drugs. Evidence suggests that long-term alcohol use and concomitant serial withdrawals permanently alter GABAergic function, down-regulate benzodiazepine binding sites, and in preclinical models lead to cell death. Benzodiazepines have substantial drawbacks in the treatment of substance use-related disorders that include interactions with alcohol, rebound effects, alcohol priming, and the risk of supplanting alcohol dependency with addiction to both alcohol and benzodiazepines. Polysubstance-dependent individuals frequently self-medicate with benzodiazepines. Selective GABA agents with novel mechanisms of action have anxiolytic, anticonvulsant, and reward inhibition profiles that have potential in treating substance use and withdrawal and enhancing relapse prevention with less liability than benzodiazepines. The GABA(B) receptor agonist baclofen has promise in relapse prevention in a number of substance dependence disorders. The GABA(A) and GABA(B) pump reuptake inhibitor tiagabine has potential for managing alcohol and sedative-hypnotic withdrawal and also possibly a role in relapse prevention.

  5. Concentration of Endogenous Secretory Receptor for Advanced Glycation End Products and Matrix Gla Protein in Controlled and Uncontrolled Type 2 Diabetes Mellitus Patients

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    Dwi Yuniati Daulay


    Full Text Available BACKGROUND: Advanced glycation end products (AGE and their receptor (RAGE system play an important role in the development of diabetic vascular complications. Recently, an endogenous secretory RAGE (esRAGE has been identified as a novel splice variant, which lacks the transmembrane domain and is secreted in human sera. Interestingly, it was reported that esRAGE binds AGE ligands and neutralizes AGE actions. Many studies have reported that diabetes mellitus correlates with vascular calcification event and increases progressively in uncontrolled diabetes. Matrix Gla Protein (MGP is known to act as an inhibitor in vascular calcification. The aim of this study was to observe progress of vascular calcification in uncontrolled diabetes patient by biochemical markers MGP as inhibitor in vascular calcification, via mechanism of AGEs. METHODS: This study was an observational study with cross sectional design on adult type 2 diabetic male patients who were defined by the 2011 Indonesian diabetes mellitus consensus criteria. RESULTS: The results of this study showed that there was a positive significant correlation between esRAGE and HbA1C (r=0.651, p=0.009, and negative correlation between MGP and HbA1C (r=-0.465, p=0.081 in controlled diabetes group. In uncontrolled diabetes group there was a positive significant correlation between MGP and HbA1C (r=0.350, p=0.023, despite the fact esRAGE showed no significant correlation with HbA1C. There was no significant difference in level of esRAGE and MGP in controlled and uncontrolled diabetes group, but MGP showed lower level in uncontrolled diabetes group, contrary to esRAGE that had higher concentration. CONCLUSIONS: In diabetes condition, complications of vascular calcification are caused by the mechanism of increased AGE formation represented by esRAGE. In diabetes control it is very important to keep the blood vessels from complications caused by vascular calcification. KEYWORDS: type 2 diabetes mellitus

  6. Triton X-100 inhibits agonist-induced currents and suppresses benzodiazepine modulation of GABA(A) receptors in Xenopus oocytes

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Ebert, Bjarke; Klaerke, Dan


    effects on gramicidin channel A appearance rate and lifetime in artificial lipid bilayers. In the present study, the pharmacological action of Triton-X 100 on GABA(A) receptors expressed in Xenopus laevis oocytes was examined. Triton-X 100 inhibited GABA(A) alpha(1)beta(3)gamma(2S) receptor currents...... by flunitrazepam at alpha(1)beta(3)gamma(2S) receptors. All effects were independent of the presence of a gamma(2S) subunit in the GABA(A) receptor complex. The present study suggests that Triton X-100 may stabilize open and desensitized states of the GABA(A) receptor through changes in lipid bilayer elasticity....... in a noncompetitive, time- and voltage-dependent manner and increased the apparent rate and extent of desensitization at 10 muM, which is 30 fold below the critical micelle concentration. In addition, Triton X-100 induced picrotoxin-sensitive GABA(A) receptor currents and suppressed allosteric modulation...

  7. Muscimol as an ionotropic GABA receptor agonist. (United States)

    Johnston, Graham A R


    Muscimol, a psychoactive isoxazole from Amanita muscaria and related mushrooms, has proved to be a remarkably selective agonist at ionotropic receptors for the inhibitory neurotransmitter GABA. This historic overview highlights the discovery and development of muscimol and related compounds as a GABA agonist by Danish and Australian neurochemists. Muscimol is widely used as a ligand to probe GABA receptors and was the lead compound in the development of a range of GABAergic agents including nipecotic acid, tiagabine, 4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol, (Gaboxadol(®)) and 4-PIOL.

  8. Efficient gamma-aminobutyric acid bioconversion by employing synthetic complex between glutamate decarboxylase and glutamate/GABA antiporter in engineered Escherichia coli. (United States)

    Le Vo, Tam Dinh; Ko, Ji-seun; Park, Si Jae; Lee, Seung Hwan; Hong, Soon Ho


    Gamma-aminobutyric acid (GABA) is a precursor of one of the most promising heat-resistant biopolymers, Nylon-4, and can be produced by the decarboxylation of monosodium glutamate (MSG). In this study, a synthetic protein complex was applied to improve the GABA conversion in engineered Escherichia coli. Complexes were constructed by assembling a single protein-protein interaction domain SH3 to the glutamate decarboxylase (GadA and GadB) and attaching a cognate peptide ligand to the glutamate/GABA antiporter (GadC) at the N-terminus, C-terminus, and the 233rd amino acid residue. When GadA and GadC were co-overexpressed via the C-terminus complex, a GABA concentration of 5.65 g/l was obtained from 10 g/l MSG, which corresponds to a GABA yield of 93 %. A significant increase of the GABA productivity was also observed where the GABA productivity increased 2.5-fold in the early culture period due to the introduction of the synthetic protein complex. The GABA pathway efficiency and GABA productivity were enhanced by the introduction of the complex between Gad and glutamate/GABA antiporter.

  9. Utilization of barley or wheat bran to bioconvert glutamate to γ-aminobutyric acid (GABA). (United States)

    Jin, Wen-Jie; Kim, Min-Ju; Kim, Keun-Sung


    This study deals with the utilization of agro-industrial wastes created by barley and wheat bran in the production of a value-added product, γ-aminobutyric acid (GABA). The simple and eco-friendly reaction requires no pretreatment or microbial fermentation steps but uses barley or wheat bran as an enzyme source, glutamate as a substrate, and pyridoxal 5'-phosphate (PLP) as a cofactor. The optimal reaction conditions were determined on the basis of the temperatures and times used for the decarboxylation reactions and the initial concentrations of barley or wheat bran, glutamate, and PLP. The optimal reactions produced 9.2 mM of GABA from 10 mM glutamate, yielding a 92% GABA conversion rate, when barley bran was used and 6.0 mM of GABA from 10 mM glutamate, yielding a 60% GABA conversion rate, when wheat bran was used. The results imply that barley bran is more efficient than wheat bran in the production of GABA. © 2013 Institute of Food Technologists®

  10. GABA expression and regulation by sensory experience in the developing visual system.

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    Loïs S Miraucourt

    Full Text Available The developing retinotectal system of the Xenopus laevis tadpole is a model of choice for studying visual experience-dependent circuit maturation in the intact animal. The neurotransmitter gamma-aminobutyric acid (GABA has been shown to play a critical role in the formation of sensory circuits in this preparation, however a comprehensive neuroanatomical study of GABAergic cell distribution in the developing tadpole has not been conducted. We report a detailed description of the spatial expression of GABA immunoreactivity in the Xenopus laevis tadpole brain at two key developmental stages: stage 40/42 around the onset of retinotectal innervation and stage 47 when the retinotectal circuit supports visually-guided behavior. During this period, GABAergic neurons within specific brain structures appeared to redistribute from clusters of neuronal somata to a sparser, more uniform distribution. Furthermore, we found that GABA levels were regulated by recent sensory experience. Both ELISA measurements of GABA concentration and quantitative analysis of GABA immunoreactivity in tissue sections from the optic tectum show that GABA increased in response to a 4 hr period of enhanced visual stimulation in stage 47 tadpoles. These observations reveal a remarkable degree of adaptability of GABAergic neurons in the developing brain, consistent with their key contributions to circuit development and function.

  11. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

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    Yan Xu

    Full Text Available Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.

  12. Glutamate/GABA+ ratio is associated with the psychosocial domain of autistic and schizotypal traits (United States)

    Nibbs, Richard; Crewther, David P.


    Background The autism and schizophrenia spectra overlap to a large degree in the social and interpersonal domains. Similarly, abnormal excitatory glutamate and inhibitory γ-aminobutyric acid (GABA) neurotransmitter concentrations have been reported for both spectra, with the interplay of these neurotransmitters important for cortical excitation to inhibition regulation. This study investigates whether these neurotransmitter abnormalities are specific to the shared symptomatology, and whether the degree of abnormality increases with increasing symptom severity. Hence, the relationship between the glutamate/GABA ratio and autism and schizophrenia spectrum traits in an unmedicated, subclinical population was investigated. Methods A total of 37 adults (19 female, 18 male) aged 18-38 years completed the Autism Spectrum Quotient (AQ) and Schizotypal Personality Questionnaire (SPQ), and participated in the resting state proton magnetic resonance spectroscopy study in which sequences specific for quantification of glutamate and GABA+ concentration were applied to a right and left superior temporal voxel. Results There were significant, moderate, positive relationships between right superior temporal glutamate/GABA+ ratio and AQ, SPQ and AQ+SPQ total scores (p<0.05), SPQ subscales Social Anxiety, No Close Friend, Constricted Affect, Odd Behaviour, Odd Speech, Ideas of Reference and Suspiciousness, and AQ subscales Social Skills, Communication and Attention Switching (p<0.05); increased glutamate/GABA+ coinciding with higher scores on these subscales. Only the relationships between glutamate/GABA+ ratio and Social Anxiety, Constricted Affect, Social Skills and Communication survived multiple comparison correction (p< 0.004). Left superior temporal glutamate/GABA+ ratio reduced with increasing restricted imagination (p<0.05). Conclusion These findings demonstrate evidence for an association between excitatory/inhibitory neurotransmitter concentrations and symptoms that are

  13. GABA and GAD expression in the X-organ sinus gland system of the Procambarus clarkii crayfish: inhibition mediated by GABA between X-organ neurons. (United States)

    Pérez-Polanco, Paola; Garduño, Julieta; Cebada, Jorge; Zarco, Natanael; Segovia, José; Lamas, Mónica; García, Ubaldo


    In crustaceans, the X-organ-sinus gland (XO-SG) neurosecretory system is formed of distinct populations of neurons that produce two families of neuropeptides: crustacean hyperglycemic hormone and adipokinetic hormone/red pigment-concentrating hormone. On the basis of electrophysiological evidence, it has been proposed that γ-aminobutyric acid (GABA) regulates both electrical and secretory activity of the XO-SG system. In this work we observed that depolarizing current pulses to neurons located in the external rim of the X-organ induced repetitive firing that suppressed the spontaneous firing of previously active X-organ neurons. Picrotoxin reversibly blocked this inhibitory effect suggesting that the GABA released from the stimulated neuron inhibited neighboring cells. Immunoperoxidase in X-organ serial sections showed co-localization of GABA and glutamic acid decarboxylase (GAD) including the aforementioned neurons. Immunofluorescence in whole mount preparations showed that two subpopulations of crustacean hyperglycemic hormone-containing neurons colocalized with GABA. The expression of GAD mRNA was determined in crayfish tissue and X-organ single cells by RT-PCR. Bioinformatics analysis shows, within the amplified region, 90.4% consensus and 41.9% identity at the amino acid level compared with Drosophila melanogaster and Caenorhabditis elegans. We suggest that crustacean hyperglycemic hormone-GABA-containing neurons can regulate the excitability of other X-organ neurons that produce different neurohormones.

  14. Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16INK4a or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection.

    Directory of Open Access Journals (Sweden)

    Brian M Maas

    Full Text Available As the HIV-infected population ages, the role of cellular senescence and inflammation on co-morbid conditions and pharmacotherapy is increasingly of interest. p16INK4a expression, a marker for aging and senescence in T-cells, is associated with lower intracellular concentrations of endogenous nucleotides (EN and nucleos(tide reverse transcriptase inhibitors (NRTIs. This study expands on these findings by determining whether inflammation is contributing to the association of p16INK4a expression with intracellular metabolite (IM exposure and endogenous nucleotide concentrations.Samples from 73 HIV-infected adults receiving daily tenofovir/emtricitabine (TFV/FTC with either efavirenz (EFV or atazanavir/ritonavir (ATV/r were tested for p16INK4a expression, and plasma cytokine and intracellular drug concentrations. Associations between p16INK4a expression and cytokine concentrations were assessed using maximum likelihood methods, and elastic net regression was applied to assess whether cytokines were predictive of intracellular metabolite/endogenous nucleotide exposures.Enrolled participants had a median age of 48 years (range 23-73. There were no significant associations between p16INK4a expression and cytokines. Results of the elastic net regression showed weak relationships between IL-1Ra and FTC-triphosphate and deoxyadenosine triphosphate exposures, and MIP-1β, age and TFV-diphosphate exposures.In this clinical evaluation, we found no relationships between p16INK4a expression and cytokines, or cytokines and intracellular nucleotide concentrations. While inflammation is known to play a role in this population, it is not a major contributor to the p16INK4a association with decreased IM/EN exposures in these HIV-infected participants.

  15. Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16INK4a or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection. (United States)

    Maas, Brian M; Francis, Owen; Mollan, Katie R; Lee, Cynthia; Cottrell, Mackenzie L; Prince, Heather M A; Sykes, Craig; Trezza, Christine; Torrice, Chad; White, Nicole; Malone, Stephanie; Hudgens, Michael G; Sharpless, Norman E; Dumond, Julie B


    As the HIV-infected population ages, the role of cellular senescence and inflammation on co-morbid conditions and pharmacotherapy is increasingly of interest. p16INK4a expression, a marker for aging and senescence in T-cells, is associated with lower intracellular concentrations of endogenous nucleotides (EN) and nucleos(t)ide reverse transcriptase inhibitors (NRTIs). This study expands on these findings by determining whether inflammation is contributing to the association of p16INK4a expression with intracellular metabolite (IM) exposure and endogenous nucleotide concentrations. Samples from 73 HIV-infected adults receiving daily tenofovir/emtricitabine (TFV/FTC) with either efavirenz (EFV) or atazanavir/ritonavir (ATV/r) were tested for p16INK4a expression, and plasma cytokine and intracellular drug concentrations. Associations between p16INK4a expression and cytokine concentrations were assessed using maximum likelihood methods, and elastic net regression was applied to assess whether cytokines were predictive of intracellular metabolite/endogenous nucleotide exposures. Enrolled participants had a median age of 48 years (range 23-73). There were no significant associations between p16INK4a expression and cytokines. Results of the elastic net regression showed weak relationships between IL-1Ra and FTC-triphosphate and deoxyadenosine triphosphate exposures, and MIP-1β, age and TFV-diphosphate exposures. In this clinical evaluation, we found no relationships between p16INK4a expression and cytokines, or cytokines and intracellular nucleotide concentrations. While inflammation is known to play a role in this population, it is not a major contributor to the p16INK4a association with decreased IM/EN exposures in these HIV-infected participants.

  16. GABA(A) receptor- and GABA transporter polymorphisms and risk for essential tremor

    DEFF Research Database (Denmark)

    Thier, S; Kuhlenbäumer, G; Lorenz, D


    Background:  Clinical features and animal models of essential tremor (ET) suggest gamma-aminobutyric acid A receptor (GABA(A) R) subunits and GABA transporters as putative candidate genes. Methods:  A total of 503 ET cases and 818 controls were investigated for an association between polymorphisms...

  17. GABA alterations in pediatric sport concussion. (United States)

    Friedman, Seth D; Poliakov, Andrew V; Budech, Christopher; Shaw, Dennis W W; Breiger, David; Jinguji, Thomas; Krabak, Brian; Coppel, David; Lewis, Tressa Mattioli; Browd, Samuel; Ojemann, Jeffrey G


    To evaluate whether frontal-lobe magnetic resonance spectroscopy measures of γ-aminobutyric acid (GABA) would be altered in a sample of adolescents scanned after sport concussion because mild traumatic brain injury is often associated with working memory problems. Eleven adolescents (age 14-17 years) who had sustained a first-time sport concussion were studied with MRI/magnetic resonance spectroscopy within 23 to 44 days after injury (mean 30.4 ± 6.1 days). Age- and sex-matched healthy controls, being seen for sports-related injuries not involving the head and with no history of concussion, were also examined. GABA/creatine + phosphocreatine (Cre) was measured in left-sided frontal lobe and central posterior cingulate regions. The frontal voxel was positioned to overlap with patient-specific activation on a 1-back working memory task. Increased GABA/Cre was shown in the frontal lobe for the concussed group. A decreased relationship was observed in the parietal region. High correlations between GABA/Cre and task activation were observed for the control group in the frontal lobe, a relationship not shown in the concussed participants. GABA/Cre appears increased in a region colocalized with working memory task activation after sport concussion. Further work extending these results in larger samples and at time points across the injury episode will aid in refining the clinical significance of these observations. © 2017 American Academy of Neurology.

  18. GABA-agonists induce the formation of low-affinity GABA-receptors on cultured cerebellar granule cells via preexisting high affinity GABA receptors

    DEFF Research Database (Denmark)

    Belhage, B; Meier, E; Schousboe, A


    -tetrahydroisoxazolo [5,4-c]pyridin-3-ol (THIP, 150 microM) or THIP plus the antagonist bicuculline methobromide (150 microM of each) or in the absence of the agonist or antagonist. Membranes isolated from granule cells cultured in a medium without the GABA agonist revealed a single binding site for GABA......The kinetics of specific GABA-binding to membranes isolated from cerebellar granule cells, cultured for 12 days from dissociated cerebella of 7-day-old rats was studied using [3H]GABA as the ligand. The granule cells were cultured in the presence of the specific GABA receptor agonist 4, 5, 6, 7...

  19. Production of gaba (γ - aminobutyric acid by microorganisms: a review

    Directory of Open Access Journals (Sweden)

    Radhika Dhakal


    Full Text Available GABA (γ-aminobutyric acid is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB, which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods.

  20. Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown). (United States)

    Beilby, Mary J; Turi, Christina E; Baker, Teesha C; Tymm, Fiona Jm; Murch, Susan J


    Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.

  1. GABA regulates the multidirectional tangential migration of GABAergic interneurons in living neonatal mice.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Inada

    Full Text Available Cortical GABAergic interneurons originate from ganglionic eminences and tangentially migrate into the cortical plate at early developmental stages. To elucidate the characteristics of this migration of GABAergic interneurons in living animals, we established an experimental design specialized for in vivo time-lapse imaging of the neocortex of neonate mice with two-photon laser-scanning microscopy. In vesicular GABA/glycine transporter (VGAT-Venus transgenic mice from birth (P0 through P3, we observed multidirectional tangential migration of genetically-defined GABAergic interneurons in the neocortical marginal zone. The properties of this migration, such as the motility rate (distance/hr, the direction moved, and the proportion of migrating neurons to stationary neurons, did not change through P0 to P3, although the density of GABAergic neurons at the marginal zone decreased with age. Thus, the characteristics of the tangential motility of individual GABAergic neurons remained constant in development. Pharmacological block of GABA(A receptors and of the Na⁺-K⁺-Cl⁻ cotransporters, and chelating intracellular Ca²⁺, all significantly reduced the motility rate in vivo. The motility rate and GABA content within the cortex of neonatal VGAT-Venus transgenic mice were significantly greater than those of GAD67-GFP knock-in mice, suggesting that extracellular GABA concentration could facilitate the multidirectional tangential migration. Indeed, diazepam applied to GAD67-GFP mice increased the motility rate substantially. In an in vitro neocortical slice preparation, we confirmed that GABA induced a NKCC sensitive depolarization of GABAergic interneurons in VGAT-Venus mice at P0-P3. Thus, activation of GABA(AR by ambient GABA depolarizes GABAergic interneurons, leading to an acceleration of their multidirectional motility in vivo.

  2. Induction of the GABA cell phenotype: an in vitro model for studying neurodevelopmental disorders.

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    Sivan Subburaju

    Full Text Available Recent studies of the hippocampus have suggested that a network of genes is associated with the regulation of the GAD₆₇ (GAD1 expression and may play a role in γ-amino butyric acid (GABA dysfunction in schizophrenia (SZ and bipolar disorder (BD. To obtain a more detailed understanding of how GAD₆₇ regulation may result in GABAergic dysfunction, we have developed an in vitro model in which GABA cells are differentiated from the hippocampal precursor cell line, HiB5. Growth factors, such as PDGF, and BDNF, regulate the GABA phenotype by inducing the expression of GAD₆₇ and stimulating the growth of cellular processes, many with growth cones that form appositions with the cell bodies and processes of other GAD₆₇-positive cells. These changes are associated with increased expression of acetylated tubulin, microtubule-associated protein 2 (MAP2 and the post-synaptic density protein 95 (PSD95. The addition of BDNF, together with PDGF, increases the levels of mRNA and protein for GAD₆₇, as well as the high affinity GABA uptake protein, GAT1. These changes are associated with increased concentrations of GABA in the cytoplasm of "differentiated" HiB5 neurons. In the presence of Ca²⁺ and K⁺, newly synthesized GABA is released extracellularly. When the HiB5 cells appear to be fully differentiated, they also express GAD₆₅, parvalbumin and calbindin, and GluR subtypes as well as HDAC1, DAXX, PAX5, Runx2, associated with GAD₆₇ regulation. Overall, these results suggest that the HiB5 cells can differentiate into functionally mature GABA neurons in the presence of gene products that are associated with GAD₆₇ regulation in the adult hippocampus.

  3. In vivo neurochemical evidence that newly synthesised GABA activates GABA(B), but not GABA(A), receptors on dopaminergic nerve endings in the nucleus accumbens of freely moving rats

    NARCIS (Netherlands)

    Saigusa, T.; Aono, Y.; Sekino, R.; Uchida, T.; Takada, K.; Oi, Y.; Koshikawa, N.; Cools, A.R.


    GABA released from accumbal GABAergic interneurons plays an inhibitory role in the regulation of dopamine efflux through GABA(B) and GABA(A) receptors located on accumbal dopaminergic nerve endings. The cytosolic newly synthesised GABA alters vesicular GABA levels and, accordingly, the amount of

  4. Glutamate and GABA contributions to medial prefrontal cortical activity to emotion: implications for mood disorders. (United States)

    Stan, Ana D; Schirda, Claudiu V; Bertocci, Michele A; Bebko, Genna M; Kronhaus, Dina M; Aslam, Haris A; LaBarbara, Eduard J; Tanase, Costin; Lockovich, Jeanette C; Pollock, Myrna H; Stiffler, Richelle S; Phillips, Mary L


    The dorsomedial prefrontal cortex (MdPFC) and anterior cingulate cortices (ACC) play a critical role in implicit emotion regulation; however the understanding of the specific neurotransmitters that mediate such role is lacking. In this study, we examined relationships between MdPFC concentrations of two neurotransmitters, glutamate and γ-amino butyric acid (GABA), and BOLD activity in ACC during performance of an implicit facial emotion-processing task. Twenty healthy volunteers, aged 20-35 years, were scanned while performing an implicit facial emotion-processing task, whereby presented facial expressions changed from neutral to one of the four emotions: happy, anger, fear, or sad. Glutamate concentrations were measured before and after the emotion-processing task in right MdPFC using magnetic resonance spectroscopy (MRS). GABA concentrations were measured in bilateral MdPFC after the emotion-processing task. Multiple regression models were run to determine the relative contribution of glutamate and GABA concentration, age, and gender to BOLD signal in ACC to each of the four emotions. Multiple regression analyses revealed a significant negative correlation between MdPFC GABA concentration and BOLD signal in subgenual ACC (pemotion processing in healthy and mood-disordered individuals. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Changes in GABA(A) receptor gene expression associated with selective alterations in receptor function and pharmacology after ethanol withdrawal. (United States)

    Sanna, Enrico; Mostallino, Maria Cristina; Busonero, Fabio; Talani, Giuseppe; Tranquilli, Stefania; Mameli, Manuel; Spiga, Saturnino; Follesa, Paolo; Biggio, Giovanni


    Changes in the expression of subunits of the GABA type A (GABA(A)) receptor are implicated in the development of ethanol tolerance and dependence as well as in the central hyperexcitability associated with ethanol withdrawal. The impact of such changes on GABA(A) receptor function and pharmacological sensitivity was investigated with cultured rat hippocampal neurons exposed to ethanol for 5 d and then subjected to ethanol withdrawal. Both ethanol treatment and withdrawal were associated with a marked decrease in the maximal density of GABA-evoked Cl- currents, whereas the potency of GABA was unaffected. Ethanol exposure also reduced the modulatory efficacy of the benzodiazepine receptor agonists lorazepam, zolpidem, and zaleplon as well as that of the inverse agonists Ro 15-4513 and FG 7142, effects that were associated with a reduced abundance of mRNAs encoding the receptor subunits alpha1, alpha3, gamma2L, and gamma2S. Ethanol withdrawal restored the efficacy of lorazepam, but not that of low concentrations of zolpidem or zaleplon, to control values. Flumazenil, which was ineffective in control neurons, and Ro 15-4513 each potentiated the GABA response after ethanol withdrawal. These effects of withdrawal were accompanied by upregulation of the alpha2, alpha3, and alpha4 subunit mRNAs as well as of the alpha4 protein. Diazepam or gamma-hydroxybutyrate, but not baclofen, prevented the changes in both GABA(A) receptor pharmacology and subunit mRNA levels induced by ethanol withdrawal. Changes in GABA(A) receptor gene expression induced by prolonged exposure to and withdrawal of ethanol are thus associated with altered GABA(A) receptor function and pharmacological sensitivity.

  6. Characterization of GABA/sub A/ receptor-mediated /sup 36/chloride uptake in rat brain synaptoneurosomes

    Energy Technology Data Exchange (ETDEWEB)

    Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.


    ..gamma..-Aminobutyric acid (GABA) receptor-mediated /sup 36/chloride (/sup 36/Cl/sup -/) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated /sup 36/Cl/sup -/ uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated /sup 36/Cl/sup -/ uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated /sup 36/Cl/sup -/ uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br/sup -/>Cl/sup -/greater than or equal toNO/sub 3//sup -/>I/sup -/greater than or equal toSCN/sup -/>>C/sub 3/H/sub 5/OO/sup -/greater than or equal toClO/sub 4//sup -/>F/sup -/, consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl/sup -/ channel. 43 references, 4 figures, 3 tables.

  7. Increased cerebrospinal fluid levels of GABA, testosterone and estradiol in women with polycystic ovary syndrome. (United States)

    Kawwass, Jennifer F; Sanders, Kristen M; Loucks, Tammy L; Rohan, Lisa Cencia; Berga, Sarah L


    Do cerebrospinal fluid (CSF) concentrations of gamma-aminobutyric acid (GABA), testosterone (T) and estradiol (E2) differ in women with polycystic ovary syndrome (PCOS) as compared to eumenorrheic, ovulatory women (EW)? Women with PCOS displayed higher CSF levels of GABA and E2, and possibly T, than EW. The chronic anovulation characteristic of PCOS has been attributed to increased central GnRH drive and resulting gonadotropin aberrations. Androgens are thought to regulate GABA, which in turn regulates the neural cascade that modulates GnRH drive. This cross-sectional observational study included 15 EW and 12 non-obese women with PCOS who consented to a lumbar puncture in addition to 24 h of serum blood collection at 15-min intervals. In total, 27 women were studied at a the General Clinical Research Center (GCRC) at the University of Pittsburgh. Serum analytes included T, E2 and androstenedione. CSF analytes included GABA, glutamate, glucose, T and E2. Women with PCOS had higher CSF GABA as compared to EW (9.04 versus 7.04 μmol/L, P gender identity issues. No conflicts of interest. The study was funded by NIH grants to SLB (RO1-MH50748, U54-HD08610) and NIH RR-00056 to the General Clinical Research Center of the University of Pittsburgh. NCT01674426.

  8. A-type GABA receptor as a central target of TRPM8 agonist menthol. (United States)

    Zhang, Xiao-Bing; Jiang, Peng; Gong, Neng; Hu, Xiao-Ling; Fei, Da; Xiong, Zhi-Qi; Xu, Lin; Xu, Tian-Le


    Menthol is a widely-used cooling and flavoring agent derived from mint leaves. In the peripheral nervous system, menthol regulates sensory transduction by activating TRPM8 channels residing specifically in primary sensory neurons. Although behavioral studies have implicated menthol actions in the brain, no direct central target of menthol has been identified. Here we show that menthol reduces the excitation of rat hippocampal neurons in culture and suppresses the epileptic activity induced by pentylenetetrazole injection and electrical kindling in vivo. We found menthol not only enhanced the currents induced by low concentrations of GABA but also directly activated GABA(A) receptor (GABA(A)R) in hippocampal neurons in culture. Furthermore, in the CA1 region of rat hippocampal slices, menthol enhanced tonic GABAergic inhibition although phasic GABAergic inhibition was unaffected. Finally, the structure-effect relationship of menthol indicated that hydroxyl plays a critical role in menthol enhancement of tonic GABA(A)R. Our results thus reveal a novel cellular mechanism that may underlie the ambivalent perception and psychophysical effects of menthol and underscore the importance of tonic inhibition by GABA(A)Rs in regulating neuronal activity.

  9. Individual Differences in Resting Corticospinal Excitability Are Correlated with Reaction Time and GABA Content in Motor Cortex. (United States)

    Greenhouse, Ian; King, Maedbh; Noah, Sean; Maddock, Richard J; Ivry, Richard B


    Individuals differ in the intrinsic excitability of their corticospinal pathways and, perhaps more generally, their entire nervous system. At present, we have little understanding of the mechanisms underlying these differences and how variation in intrinsic excitability relates to behavior. Here, we examined the relationship between individual differences in intrinsic corticospinal excitability, local cortical GABA levels, and reaction time (RT) in a group of 20 healthy human adults. We measured corticospinal excitability at rest with transcranial magnetic stimulation, local concentrations of basal GABA with magnetic resonance spectroscopy, and RT with a behavioral task. All measurements were repeated in two separate sessions, and tests of reliability confirmed the presence of stable individual differences. There was a negative correlation between corticospinal excitability and RT, such that larger motor-evoked potentials (MEPs) measured at rest were associated with faster RTs. Interestingly, larger MEPs were associated with higher levels of GABA in M1, but not in three other cortical regions. Together, these results suggest that individuals with more excitable corticospinal pathways are faster to initiate planned responses and have higher levels of GABA within M1, possibly to compensate for a more excitable motor system.SIGNIFICANCE STATEMENT This study brings together physiological, behavioral, and neurochemical evidence to examine variability in the excitability of the human motor system. Previous work has focused on state-based factors (e.g., preparedness, uncertainty), with little attention given to the influence of inherent stable characteristics. Here, we examined how the excitability of the motor system relates to reaction time and the regional content of the inhibitory neurotransmitter GABA. Importantly, motor pathway excitability and GABA concentrations were measured at rest, outside a task context, providing assays of intrinsic properties of the

  10. Chemometric endogenous fluorescence for tissue diagnosis (United States)

    Li, Run; Vasquez, Kevin; Xu, M.


    Endogenous fluorescence is a powerful technique for probing both structure and function of tissue. We show that enabling wide-field fluorescence microscopy with chemometrics can significantly enhance the performance of tissue diagnosis with endogenous fluorescence. The spatial distribution and absolute concentration of fluorophores is uncovered with non-negative factorization aided by the spatial diversity from microscopic autofluorescence color images. Fluorescence quantification in terms of its absolute concentration map avoids issues dependent on specific measurement approach or systems and yields biologically meaningful data. The standardization of endogenous fluorescence in terms of absolute concentration will facilitate its translation to the clinics and simplifies the assessment of competing methods relating to tissue fluorescence.

  11. Excitatory actions of GABA in developing chick vestibular afferents: effects on resting electrical activity. (United States)

    Cortes, Celso; Galindo, Fabian; Galicia, Salvador; Cebada, Jorge; Flores, Amira


    The aim of this study was to characterize the effect of γ-aminobutyric acid (GABA) in the resting multiunit activity of the vestibular afferents during development using the isolated inner ear of embryonic and postnatal chickens (E15-E21 and P5). GABA (10(-3) to 10(-5) M; n = 133) and muscimol (10(-3) M) elicited an increase in the frequency of the basal discharge of the vestibular afferents. We found that GABA action was dose-dependent and inversely related to animal age. Thus, the largest effect was observed in embryonic ages such as E15 and E17 and decreases in E21 and P5. The GABAA receptor antagonists, bicuculline (10(-5) M; n = 10) and picrotoxin (10(-4) M; n = 10), significantly decreased the excitatory action of GABA and muscimol (10(-3) M). Additionally, CNQX 10(-6) M, MCPG 10(-5) M and 7ClKyn 10(-5) M (n = 5) were co-applied by bath substitution (n = 5). Both the basal discharge and the GABA action significantly decreased in these experimental conditions. The chloride channel blocker 9-AC 0.5 mM produced an important reduction in the effect of GABA 10(-3) (n = 5) and 10(-4) M (n = 5). Thus, our results suggest an excitatory role of GABA in the resting activity of the vestibular afferents that can be explained by changes in the gradient of concentration of Cl(-) during development. We show for the first time that the magnitude of this GABA effect decreases at later stages of embryonic and early postnatal development. Taking into account the results with glutamatergic antagonists, we conclude that GABA has a presynaptic action but is not the neurotransmitter in the vestibular afferent synapses, although it could act as a facilitator of the spontaneous activity and may regulate glutamate release. Copyright © 2013 Wiley Periodicals, Inc.

  12. Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations

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    D' Have, Helga [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)]. E-mail:; Scheirs, Jan [Evolutionary Biology Group, Department of Biology, University of Antwerp, B-2020 Antwerp (Belgium); Mubiana, Valentine Kayawe [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Verhagen, Ron [Evolutionary Biology Group, Department of Biology, University of Antwerp, B-2020 Antwerp (Belgium); Blust, Ronny [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Coen, Wim de [Ecophysiology, Biochemistry and Toxicology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)


    The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 < r < 0.85). Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 < r < 0.62). Hair Ag, As, Fe and Zn and spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 < r < 0.45). The regression models presented here may be used to predict metal and As concentrations in internal tissues of hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs. - Hedgehog hair and spines are promising non-destructive biomonitoring tools of terrestrial metal pollution.

  13. Synthesis, brain uptake, and pharmacological properties of a glyceryl lipid containing GABA and the GABA-T inhibitor gamma-vinyl-GABA. (United States)

    Jacob, J N; Hesse, G W; Shashoua, V E


    1-O-Linolenoyl-2-O-(4-aminobutyryl)-3-O-(4-vinyl-4-aminobutyryl)glycerol (LGV) was synthesized as an example of a prodrug which readily penetrates the blood-brain barrier (brain penetration index 97% +/- 15%) and releases two active substances in the central nervous system (CNS): GABA (4-aminobutanoic acid) and the GABA transaminase inhibitor (GABA-T) of GABA breakdown. In vitro studies showed that the compound can inhibit GABA-T after hydrolysis by CNS esterases and that it enhanced GABAergic inhibition when applied to rat hippocampus slices. In vivo studies indicate that LGV depresses the spontaneous locomotor activity of mice. Its activity on a molar basis was some 300 times greater than that of gamma-vinyl-GABA.

  14. The effects of cyclopentane and cyclopentene analogues of GABA at recombinant GABA(C) receptors. (United States)

    Chebib, M; Duke, R K; Allan, R D; Johnston, G A


    The pharmacological effects of the enantiomers of cis-3-aminocyclopentanecarboxylic acids ((+)- and (-)-CACP), the enantiomers of trans-3-aminocyclopentanecarboxylic acids ((+)- and (-)-TACP), and the enantiomers of 4-aminocyclopent-1-ene-1-carboxylic acids ((+)- and (-)-4-ACPCA) were studied on human homomeric rho(1) and rho(2) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp methods. These compounds are conformationally restricted analogues of gamma-aminobutyric acid (GABA) held in a five-membered ring. (+)-TACP (EC(50) (rho(1))=2.7+/-0.2 microM; EC(50) (rho(2))=1.45+/-0.22 microM), (+)-CACP (EC(50) (rho(1))=26.1+/-1.1 microM; EC(50) (rho(2))=20.1+/-2.1 microM) and (-)-CACP (EC(50) (rho(1))=78.5+/-3.5 microM; EC(50) (rho(2))=63.8+/-23.3 microM) were moderately potent partial agonists at rho(1) and rho(2) GABA(C) receptors, while (-)-TACP (100 microM inhibited 56% and 62% of the current produced by 1 microM GABA at rho(1) and rho(2) receptors, respectively) was a weak partial agonist with low intrinsic activity at these receptors. In contrast, (+)-4-ACPCA (K(i) (rho(1))=6.0+/-0.1 microM; K(i) (rho(2))=4.7+/-0.3 microM) did not activate GABA(C) rho(1) and rho(2) receptors but potently inhibited the action of GABA at these receptors, while (-)-4-ACPCA had little effect as either an agonist or an antagonist. The affinity order at both GABA(C) rho(1) and rho(2) receptors was (+)-TACP>(+)-4-ACPCA > (+)-CACP>(-)-CACP > (-)-TACP > (-)-4-ACPCA. This study shows that the cyclopentane and cyclopentene analogues of GABA affect GABA(C) receptors in a unique manner, defining a preferred stereochemical orientation of the amine and carboxylic acid groups when binding to GABA(C) receptors. This is exemplified by the partial agonist, (+)-TACP, and the antagonist, (+)-4-ACPCA.

  15. GABA Uptake Inhibition Reduces In Vivo Extraction Fraction in the Ventral Tegmental Area of Long Evans Rats Measured by Quantitative Microdialysis Under Transient Conditions. (United States)

    Zandy, Shannon L; Gonzales, Rueben A


    Inhibitory signaling in the ventral tegmental area (VTA) is involved in the mechanism of action for many drugs of abuse. Although drugs of abuse have been shown to alter extracellular γ-aminobutyric acid (GABA) concentration in the VTA, knowledge on how uptake mechanisms are regulated in vivo is limited. Quantitative (no-net-flux) microdialysis is commonly used to examine the extracellular concentration and clearance of monoamine neurotransmitters, however it is unclear whether this method is sensitive to changes in clearance for amino acid neurotransmitters such as GABA. The purpose of this study was to determine whether changes in GABA uptake are reflected by in vivo extraction fraction within the VTA. Using quantitative (no-net-flux) microdialysis adapted for transient conditions, we examined the effects of local perfusion with the GABA uptake inhibitor, nipecotic acid, in the VTA of Long Evans rats. Basal extracellular GABA concentration and in vivo extraction fraction were 44.4 ± 1.9 nM (x-intercepts from 4 baseline regressions using a total of 24 rats) and 0.19 ± 0.01 (slopes from 4 baseline regressions using a total of 24 rats), respectively. Nipecotic acid (50 μM) significantly increased extracellular GABA concentration to 170 ± 4 nM and reduced in vivo extraction fraction to 0.112 ± 0.003. Extraction fraction returned to baseline following removal of nipecotic acid from the perfusate. Conventional microdialysis substantially underestimated the increase of extracellular GABA concentration due to nipecotic acid perfusion compared with that obtained from the quantitative analysis. Together, these results show that inhibiting GABA uptake mechanisms within the VTA alters in vivo extraction fraction measured using microdialysis and that in vivo extraction fraction may be an indirect measure of GABA clearance.

  16. Functional loss of GABA transaminase (GABA-T expressed early leaf senescence under various stress conditions in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Syed Uzma Jalil


    Full Text Available GABA-transaminase (GABA-T involved in carbon and nitrogen metabolism during the plant development process via GABA shunt and GABA-T mutant, which is defective in GABA catabolism, is ideal model to examine the role of GABA-T in plant development and leaf senescence of plant. We have characterized GABA transaminase knock out mutant pop2-1 that is transition and pop2-3 which is T-DNA insertion mutant of Arabidopsis thaliana during various stress conditions.The GABA-T knockout mutant plants displayed precocious leaf senescence, which was accompanied by the assays of physiological parameters of leaf senescence during various stress conditions. Furthermore, our physiological evidence indicates that pop2-1 and pop2-3 mutations rapidly decreased the efficiency of leaf photosynthesis, chlorophyll content, GABA content, GABA-T, and glutamate decarboxylase (GAD activity and on the other hand increases membrane ion leakage, malondialdehyde (MDA level in stress induced leaves. However, cell viability assay by trypan blue and insitu Hydrogen peroxidation assay by 3,3-diaminobenzidine (DAB in stress induced leaves also display that pop2-1 and pop2-3 mutant leaves show oversensitivity in response to different stress conditions as compared to wild type. These results strongly indicate that the loss-of-function of GABA transaminase gene induces early leaf senescence in Arabidopsis thaliana during various stress conditions.

  17. Effects of ethylenediamine--a putative GABA-releasing agent--on rat hippocampal slices and neocortical activity in vivo. (United States)

    Stone, Trevor W; Lui, Caleb; Addae, Jonas I


    The simple diamine diaminoethane (ethylenediamine, EDA) has been shown to activate GABA receptors in the central and peripheral nervous systems, partly by a direct action and partly by releasing endogenous GABA. These effects have been shown to be produced by the complexation of EDA with bicarbonate to form a carbamate. The present work has compared EDA, GABA and β-alanine responses in rat CA1 neurons using extracellular and intracellular recordings, as well as neocortical evoked potentials in vivo. Superfusion of GABA onto hippocampal slices produced depolarisation and a decrease of field epsps, both effects fading rapidly, but showing sensitivity to blockade by bicuculline. EDA produced an initial hyperpolarisation and increase of extracellular field epsp size with no fade and only partial sensitivity to bicuculline, with subsequent depolarisation, while β-alanine produces a much larger underlying hyperpolarisation and increase in fepsps, followed by depolarisation and inhibition of fepsps. The responses to β-alanine, but not GABA or EDA, were blocked by strychnine. In vivo experiments, recording somatosensory evoked potentials, confirmed that EDA produced an initial increase followed by depression, and that this effect was not fully blocked by bicuculline. Overall the results indicate that EDA has actions in addition to the activation of GABA receptors. These actions are not attributable to activation of β-alanine-sensitive glycine receptors, but may involve the activation of sites sensitive to adipic acid, which is structurally equivalent to the dicarbamate of EDA. The results emphasise the complex pharmacology of simple amines in bicarbonate-containing solutions. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation. (United States)

    Qin, Pengmin; Duncan, Niall W; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J; Northoff, Georg


    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  19. Effects of pregnancy and delivery on serum concentrations of Clara Cell Protein (CC16), an endogenous anticytokine: lower serum CC16 is related to postpartum depression (United States)

    Maes; Ombelet; Libbrecht; Stevens; Kenis; De Jongh R; Lin; Cox; Bosmans


    There is now some evidence that lower serum concentrations of Clara Cell Protein (CC16) are related to stress-induced anxiety, psychoses and major depression. This study was developed to determine whether serum CC16 is lowered in the early puerperium and whether Postnatal Depression and Postnatal Blues are associated with lower levels of serum CC16. Serum concentrations of CC16 were assayed in 17 non-pregnant women and in 98 pregnant women before delivery and 1 and 3 days after delivery. On each occasion the parturients completed the State version of the Spielberger State-Trait Anxiety Inventory (STAI) and the Zung Depression Rating Scale (ZDS). Serum CC16 was significantly lower in pregnant women, at the end of pregnancy as well as 1 and 3 days after delivery, than in the non-pregnant women. Serum CC16 was somewhat, although significantly, higher 1 and 3 days after delivery than before delivery. Parturients who developed a postpartum depression had significantly lower serum CC16 concentrations than women who did not. There were no significant differences in serum CC16 between the puerperal women whose STAI or ZDS scores increased in the puerperium and those whose scores did not. It is concluded that in puerperal women there is a decreased anti-inflammatory capacity in the serum, in part caused by lowered serum CC16, and that the latter may be related to the development of postpartum depression.

  20. Glutamate and GABA as rapid effectors of hypothalamic peptidergic neurons

    Directory of Open Access Journals (Sweden)

    Cornelia eSchöne


    Full Text Available Vital hypothalamic neurons regulating hunger, wakefulness, reward-seeking, and body weight are often defined by unique expression of hypothalamus-specific neuropeptides. Gene-ablation studies show that some of these peptides, notably orexin/hypocretin (hcrt/orx, are themselves critical for stable states of consciousness and metabolic health. However, neuron-ablation studies often reveal more severe phenotypes, suggesting key roles for co-expressed transmitters. Indeed, most hypothalamic neurons, including hcrt/orx cells, contain fast transmitters glutamate and GABA, as well as several neuropeptides. What are the roles and relations between different transmitters expressed by the same neuron? Here, we consider signaling codes for releasing different transmitters in relation to transmitter and receptor diversity in behaviorally-defined, widely-projecting peptidergic neurons, such as hcrt/orx cells. We then discuss latest optogenetic studies of endogenous transmitter release from defined sets of axons in situ, which suggest that recently-characterized vital peptidergic neurons (e.g. hcrt/orx, proopiomelanocortin , and agouti-related peptide cells, as well as classical modulatory neurons (e.g. dopamine and acetylcholine cells, all use fast transmitters to control their postsynaptic targets. These optogenetic insights are complemented by recent observations of behavioral deficiencies caused by genetic ablation of fast transmission from specific neuropeptidergic and aminergic neurons. Powerful and fast (millisecond-scale GABAergic and glutamatergic signaling from neurons previously considered to be primarily modulatory raises new questions about the roles of slower co-transmitters they co-express.

  1. The Glutamine-Glutamate/GABA Cycle

    DEFF Research Database (Denmark)

    Walls, Anne B; Waagepetersen, Helle S; Bak, Lasse Kristoffer


    The operation of a glutamine-glutamate/GABA cycle in the brain consisting of the transfer of glutamine from astrocytes to neurons and neurotransmitter glutamate or GABA from neurons to astrocytes is a well-known concept. In neurons, glutamine is not only used for energy production and protein...... synthesis, as in other cells, but is also an essential precursor for biosynthesis of amino acid neurotransmitters. An excellent tool for the study of glutamine transfer from astrocytes to neurons is [(14)C]acetate or [(13)C]acetate and the glial specific enzyme inhibitors, i.e. the glutamine synthetase...... information about glutamine transfer. The present review will give information about glutamine trafficking and the tools used to map it as exemplified by discussions of published work employing brain cell cultures as well as intact animals. It will be documented that considerably more glutamine is transferred...

  2. The GABA Hypothesis in Essential Tremor: Lights and Shadows. (United States)

    Gironell, Alexandre


    The gamma-aminobutyric acid (GABA) hypothesis in essential tremor (ET) implies a disturbance of the GABAergic system, especially involving the cerebellum. This review examines the evidence of the GABA hypothesis. The review is based on published data about GABA dysfunction in ET, taking into account studies on cerebrospinal fluid, pathology, electrophysiology, genetics, neuroimaging, experimental animal models, and human drug therapies. Findings from several studies support the GABA hypothesis in ET. The hypothesis follows four steps: 1) cerebellar neurodegeneration with Purkinje cell loss; 2) a decrease in GABA system activity in deep cerebellar neurons; 3) disinhibition in output deep cerebellar neurons with pacemaker activity; and 4) an increase in rhythmic activity of the thalamus and thalamo-cortical circuit, contributing to the generation of tremor. Doubts have been cast on this hypothesis, however, by the fact that it is based on relatively few works, controversial post-mortem findings, and negative genetic studies on the GABA system. Furthermore, GABAergic drug efficacy is low and some GABAergic drugs do not have antitremoric efficacy. The GABA hypothesis continues to be the most robust pathophysiological hypothesis to explain ET. There is light in all GABA hypothesis steps, but a number of shadows cannot be overlooked. We need more studies to clarify the neurodegenerative nature of the disease, to confirm the decrease of GABA activity in the cerebellum, and to test more therapies that enhance the GABA transmission specifically in the cerebellum area.

  3. Adelmidrol increases the endogenous concentrations of palmitoylethanolamide in canine keratinocytes and down-regulates an inflammatory reaction in an in vitro model of contact allergic dermatitis. (United States)

    Petrosino, S; Puigdemont, A; Della Valle, M F; Fusco, M; Verde, R; Allarà, M; Aveta, T; Orlando, P; Di Marzo, V


    This study aimed to investigate potential new target(s)/mechanism(s) for the palmitoylethanolamide (PEA) analogue, adelmidrol, and its role in an in vitro model of contact allergic dermatitis. Freshly isolated canine keratinocytes, human keratinocyte (HaCaT) cells and human embryonic kidney (HEK)-293 cells, wild-type or transfected with cDNA encoding for N-acylethanolamine-hydrolysing acid amidase (NAAA), were treated with adelmidrol or azelaic acid, and the concentrations of endocannabinoids (anandamide and 2-arachidonoylglycerol) and related mediators (PEA and oleoylethanolamide) were measured. The mRNA expression of PEA catabolic enzymes (NAAA and fatty acid amide hydrolase, FAAH), and biosynthetic enzymes (N-acyl phosphatidylethanolamine-specific phospholipase D, NAPE-PLD) and glycerophosphodiester phosphodiesterase 1, was also measured. Brain or HEK-293 cell membrane fractions were used to assess the ability of adelmidrol to inhibit FAAH and NAAA activity, respectively. HaCaT cells were stimulated with polyinosinic-polycytidylic acid and the release of the pro-inflammatory chemokine, monocyte chemotactic protein-2 (MCP-2), was measured in the presence of adelmidrol. Adelmidrol increased PEA concentrations in canine keratinocytes and in the other cellular systems studied. It did not inhibit the activity of PEA catabolic enzymes, although it reduced their mRNA expression in some cell types. Adelmidrol modulated the expression of PEA biosynthetic enzyme, NAPE-PLD, in HaCaT cells, and inhibited the release of the pro-inflammatory chemokine MCP-2 from stimulated HaCaT cells. This study demonstrates for the first time an 'entourage effect' of adelmidrol on PEA concentrations in keratinocytes and suggests that this effect might mediate, at least in part, the anti-inflammatory effects of this compound in veterinary practice. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. GABA uptake inhibitors. Design, molecular pharmacology and therapeutic aspects

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, P; Frølund, B; Frydenvang, Karla Andrea


    In the mid seventies a drug design programme using the Amanita muscaria constituent muscimol (7) as a lead structure, led to the design of guvacine (23) and (R)-nipecotic acid (24) as specific GABA uptake inhibitors and the isomeric compounds isoguvacine (10) and isonipecotic acid (11) as specific...... GABAA receptor agonists. The availability of these compounds made it possible to study the pharmacology of the GABA uptake systems and the GABAA receptors separately. Based on extensive cellular and molecular pharmacological studies using 23, 24, and a number of mono- and bicyclic analogues, it has been...... as well as glial GABA uptake in order to enhance the inhibitory effects of synaptically released GABA, or (2) selective blockade of glial GABA uptake in order to increase the amount of GABA taken up into, and subsequently released from, nerve terminals. The bicyclic compound (R)-N-Me-exo-THPO (17) has...

  5. Occipital GABA correlates with cognitive failures in daily life. (United States)

    Sandberg, Kristian; Blicher, Jakob Udby; Dong, Mia Yuan; Rees, Geraint; Near, Jamie; Kanai, Ryota


    The brain has limited capacity, and so selective attention enhances relevant incoming information while suppressing irrelevant information. This process is not always successful, and the frequency of such cognitive failures varies to a large extent between individuals. Here we hypothesised that individual differences in cognitive failures might be reflected in inhibitory processing in the sensory cortex. To test this hypothesis, we measured GABA in human visual cortex using MR spectroscopy and found a negative correlation between occipital GABA (GABA+/Cr ratio) and cognitive failures as measured by an established cognitive failures questionnaire (CFQ). For a second site in parietal cortex, no correlation between CFQ score and GABA+/Cr ratio was found, thus establishing the regional specificity of the link between occipital GABA and cognitive failures. We further found that grey matter volume in the left superior parietal lobule (SPL) correlated with cognitive failures independently from the impact of occipital GABA and together, occipital GABA and SPL grey matter volume statistically explained around 50% of the individual variability in daily cognitive failures. We speculate that the amount of GABA in sensory areas may reflect the potential capacity to selectively suppress irrelevant information already at the sensory level, or alternatively that GABA influences the specificity of neural representations in visual cortex thus improving the effectiveness of successful attentional modulation. © 2013. Published by Elsevier Inc. All rights reserved.

  6. Evaluation of commercial soy sauce koji strains of Aspergillus oryzae for γ-aminobutyric acid (GABA) production. (United States)

    Ab Kadir, Safuan; Wan-Mohtar, Wan Abd Al Qadr Imad; Mohammad, Rosfarizan; Abdul Halim Lim, Sarina; Sabo Mohammed, Abdulkarim; Saari, Nazamid


    In this study, four selected commercial strains of Aspergillus oryzae were collected from soy sauce koji. These A. oryzae strains designated as NSK, NSZ, NSJ and NST shared similar morphological characteristics with the reference strain (A. oryzae FRR 1675) which confirmed them as A. oryzae species. They were further evaluated for their ability to produce γ-aminobutyric acid (GABA) by cultivating the spore suspension in a broth medium containing 0.4 % (w/v) of glutamic acid as a substrate for GABA production. The results showed that these strains were capable of producing GABA; however, the concentrations differed significantly (P oryzae strains, highest GABA concentration was obtained from NSK (194 mg/L) followed by NSZ (63 mg/L), NSJ (51.53 mg/L) and NST (31.66 mg/L). Therefore, A. oryzae NSK was characterized and the sequence was found to be similar to A. oryzae and A. flavus with 99 % similarity. The evolutionary distance (K nuc) between sequences of identical fungal species was calculated and a phylogenetic tree prepared from the K nuc data showed that the isolate belonged to the A. oryzae species. This finding may allow the development of GABA-rich ingredients using A. oryzae NSK as a starter culture for soy sauce production.

  7. Temporal development of GABA agonist induced alterations in ultrastructure and GABA receptor expression in cultured cerebellar granule cells

    DEFF Research Database (Denmark)

    Hansen, G H; Belhage, B; Schousboe, A


    The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays. It was f......The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays...

  8. GABA agonist promoted formation of low affinity GABA receptors on cerebellar granule cells is restricted to early development

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, G H; Schousboe, A


    The ability of the GABA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) to promote formation of low affinity GABA receptors on cerebellar granule cells was tested using primary cultures of these neurons. Granule cells were exposed to THIP (150 microM) for 6 hr after, respec...... cells expressed a high density of high affinity GABA receptors. It is concluded that the ability of THIP to promote formation of low affinity GABA receptors on cerebellar granule cells is restricted to an early developmental period....

  9. Endogenous price leadership


    van Damme, E.E.C.; Hurkens, S.


    We consider a linear price setting duopoly game with differentiated products and determine endogenously which of the players will lead and which will follow. While the follower role is most attractive for each firm, we show that waiting is more risky for the low cost firm so that, consequently, risk dominance considerations, as in Harsanyi and Selten (1988), allow the conclusion that only the high cost firm will choose to wait. Hence, the low cost firm will emerge as the endogenous price leader.

  10. A mitochondrial GABA permease connects the GABA shunt and the TCA cycle, and is essential for normal carbon metabolism. (United States)

    Michaeli, Simon; Fait, Aaron; Lagor, Kelly; Nunes-Nesi, Adriano; Grillich, Nicole; Yellin, Ayelet; Bar, Dana; Khan, Munziba; Fernie, Alisdair R; Turano, Frank J; Fromm, Hillel


    In plants, γ-aminobutyric acid (GABA) accumulates in the cytosol in response to a variety of stresses. GABA is transported into mitochondria, where it is catabolized into TCA cycle or other intermediates. Although there is circumstantial evidence for mitochondrial GABA transporters in eukaryotes, none have yet been identified. Described here is an Arabidopsis protein similar in sequence and topology to unicellular GABA transporters. The expression of this protein complements a GABA-transport-deficient yeast mutant. Thus the protein was termed AtGABP to indicate GABA-permease activity. In vivo localization of GABP fused to GFP and immunobloting of subcellular fractions demonstrate its mitochondrial localization. Direct [(3) H]GABA uptake measurements into isolated mitochondria revealed impaired uptake into mitochondria of a gabp mutant compared with wild-type (WT) mitochondria, implicating AtGABP as a major mitochondrial GABA carrier. Measurements of CO(2) release, derived from radiolabeled substrates in whole seedlings and in isolated mitochondria, demonstrate impaired GABA-derived input into the TCA cycle, and a compensatory increase in TCA cycle activity in gabp mutants. Finally, growth abnormalities of gabp mutants under limited carbon availability on artificial media, and in soil under low light intensity, combined with their metabolite profiles, suggest an important role for AtGABP in primary carbon metabolism and plant growth. Thus, AtGABP-mediated transport of GABA from the cytosol into mitochondria is important to ensure proper GABA-mediated respiration and carbon metabolism. This function is particularly essential for plant growth under conditions of limited carbon. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  11. Effect of Songyu Anshen Fang on expression of hypothalamic GABA ...

    African Journals Online (AJOL)

    Moreover, GABA(B) receptor, mRNA and protein expression decreased by PCPA in hypothalamus were significantly normalized by SYF. Conclusion: The study indicates that the effects of PCPA-induced insomnia can be alleviated by SYF modulation of neurotransmitter levels and the expression of GABA(B) receptor in the ...

  12. GABA shunt enzymes and the relationship with morphine abstinence

    NARCIS (Netherlands)

    Th. de Boer (Thijs)


    textabstractSelective inhibition of tbe rate-limiting step in tbe degradation of tbe inhibitory neurotransmitter Y·aminobutyric acid (GABA) might be of potential use in the treatment of many neurological or psychiatric disorders since it might correct a central GABA deficiency. Alternatively, as

  13. Perisynaptic GABA Receptors: The Overzealous Protector

    Directory of Open Access Journals (Sweden)

    Andrew N. Clarkson


    Full Text Available An attempt to find pharmacological therapies to treat stroke patients and minimize the extent of cell death has seen the failure of dozens of clinical trials. As a result, stroke/cerebral ischemia is the leading cause of lasting adult disability. Stroke-induced cell death occurs due to an excess release of glutamate. As a consequence to this, a compensatory increased release of GABA occurs that results in the subsequent internalization of synaptic GABAA receptors and spillover onto perisynaptic GABAA receptors, resulting in increased tonic inhibition. Recent studies show that the brain can engage in a limited process of neural repair after stroke. Changes in cortical sensory and motor maps and alterations in axonal structure are dependent on patterned neuronal activity. It has been assumed that changes in neuronal excitability underlie processes of neural repair and remapping of cortical sensory and motor representations. Indeed, recent evidence suggests that local inhibitory and excitatory currents are altered after stroke and modulation of these networks to enhance excitability during the repair phase can facilitate functional recovery after stroke. More specifically, dampening tonic GABA inhibition can afford an early and robust improvement in functional recovery after stroke.

  14. The Regulation of Endogenous Glutamate and GABA Release from In Vitro Preparations of Rat Striatum (United States)


    Butcher SP~ JW Lazarewicz and A Hamberger, In vivo microdialysis studies on the effects of decortication and excitotoxic lesions on kainic acid-induced...striatum and cerebral cortex of guinea pig and rat. Neurosci. 31 (1989). 313-25. Lapper SR and JP Bolam. Input from the frontal cortex and the papafascicuIar

  15. Alterations of GABA and glutamate-glutamine levels in premenstrual dysphoric disorder: a 3T proton magnetic resonance spectroscopy study. (United States)

    Liu, Bo; Wang, Guangbin; Gao, Dongmei; Gao, Fei; Zhao, Bin; Qiao, Mingqi; Yang, Huan; Yu, Yanhong; Ren, Fuxin; Yang, Ping; Chen, Weibo; Rae, Caroline D


    Increasing evidence has suggested that the GABAergic neurotransmitter system is involved in the pathogenesis of premenstrual dysphoric disorder (PMDD). We used proton magnetic resonance spectroscopy ((1)H MRS) to investigate whether PMDD is associated with alterations in brain GABA levels. Levels of glutamate-glutamine (Glx) were also explored. Participants comprised 22 women with PMDD and 22 age-matched healthy controls who underwent 3T (1)H MRS during the late luteal phase of the menstrual cycle. GABA+ and Glx levels were quantified in the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and the left basal ganglia (ltBG). Water-scaled GABA+ concentrations and GABA+/tCr ratios were significantly lower in both the ACC/mPFC and ltBG regions of PMDD women than in healthy controls. Glx/tCr ratios were significantly higher in the ACC/mPFC region of PMDD women than healthy controls. Our preliminary findings provide the first report of abnormal levels of GABA+ and Glx in mood-related brain regions of women with PMDD, indicating that dysregulation of the amino acid neurotransmitter system may be an important neurobiological mechanism in the pathogenesis of PMDD. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  16. Study of GABA in healthy volunteers: pharmacokinetics and pharmacodynamics

    Directory of Open Access Journals (Sweden)

    Junfeng eLi


    Full Text Available Preclinical studies show that GABA exerts anti-diabetic effects in rodent models of type 1 diabetes. Because little is known about its absorption and effects in humans, we investigated the pharmacokinetics and pharmacodynamics of GABA in healthy volunteers. Twelve subjects were subjected to an open-labeled, three-period trial involving sequential oral administration of placebo, 2g GABA once, and 2g GABA three times/day for seven days, with a 7-day washout between each period. GABA was rapidly absorbed (Tmax: 0.5~1 h with the half-life (t1/2 of 5 h. No accumulation was observed after repeated oral GABA administration for 7 days. Remarkably, GABA significantly increased circulating insulin levels in the subjects under either fasting (1.6-fold, single dose; 2.0-fold, repeated dose; p<0.01 or fed conditions (1.4-fold, single dose; 1.6-fold, repeated dose; p<0.01. GABA also increased glucagon levels only under fasting conditions (1.3-fold, single dose, p<0.05; 1.5-fold, repeated dose, p<0.01. However, there were no significant differences in the insulin-to-glucagon ratio and no significant change in glucose levels in these healthy subjects during the study period. Importantly, GABA significantly decreased glycated albumin levels in the repeated dosing period. Subjects with repeated dosing showed an elevated incidence of minor adverse events in comparison to placebo or the single dosing period, most notably transitional discomforts such as dizziness and sore throat. However, there were no serious adverse events observed throughout the study. Our data show that GABA is rapidly absorbed and tolerated in human beings; its endocrine effects, exemplified by increasing islet hormonal secretion, suggest potential therapeutic benefits for diabetes.

  17. GABA agonist promoted formation of low affinity GABA receptors on cerebellar granule cells is restricted to early development

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, Gert Helge; Schousboe, A


    The ability of the GABA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) to promote formation of low affinity GABA receptors on cerebellar granule cells was tested using primary cultures of these neurons. Granule cells were exposed to THIP (150 microM) for 6 hr after......, respectively, 4, 7, 10 and 14 days in culture. It was found that THIP treatment of 4- and 7-day-old cultures led to formation of low affinity GABA receptors, whereas such receptors could not be detected after THIP treatment in the older cultures (10 and 14 days) in spite of the fact that these cultured granule...... cells expressed a high density of high affinity GABA receptors. It is concluded that the ability of THIP to promote formation of low affinity GABA receptors on cerebellar granule cells is restricted to an early developmental period....

  18. Local impermeant anions establish the neuronal chloride concentration

    DEFF Research Database (Denmark)

    Glykys, J; Dzhala, V; Egawa, K


    Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of γ-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane, but accumulat...... anions determine the homeostatic set point for [Cl(-)], and hence, neuronal volume and the polarity of local GABA(A)R signaling....

  19. Impairment of GABA transporter GAT-1 terminates cortical recurrent network activity via enhanced phasic inhibition

    Directory of Open Access Journals (Sweden)

    Daniel Simon Razik


    Full Text Available In the central nervous system, GABA transporters (GATs very efficiently clear synaptically released GABA from the extracellular space, and thus exert a tight control on GABAergic inhibition. In neocortex, GABAergic inhibition is heavily recruited during recurrent phases of spontaneous action potential activity which alternate with neuronally quiet periods. Therefore, such activity should be quite sensitive to minute alterations of GAT function. Here, we explored the effects of a gradual impairment of GAT-1 and GAT-2/3 on spontaneous recurrent network activity – termed network bursts and silent periods – in organotypic slice cultures of rat neocortex. The GAT-1 specific antagonist NO-711 depressed activity already at nanomolar concentrations (IC50 for depression of spontaneous multiunit firing rate of 42 nM, reaching a level of 80% at 500-1000 nM. By contrast, the GAT-2/3 preferring antagonist SNAP-5114 had weaker and less consistent effects. Several lines of evidence pointed towards an enhancement of phasic GABAergic inhibition as the dominant activity-depressing mechanism: network bursts were drastically shortened, phasic GABAergic currents decayed slower, and neuronal excitability during ongoing activity was diminished. In silent periods, NO-711 had little effect on neuronal excitability or membrane resistance, quite in contrast to the effects of muscimol, a GABA mimetic which activates GABAA receptors tonically. Our results suggest that an enhancement of phasic GABAergic inhibition efficiently curtails cortical recurrent activity and may mediate antiepileptic effects of therapeutically relevant concentrations of GAT-1 antagonists.

  20. Perisylvian GABA levels in schizophrenia and bipolar disorder. (United States)

    Atagün, Murat İlhan; Şıkoğlu, Elif Muazzez; Soykan, Çağlar; Serdar Süleyman, Can; Ulusoy-Kaymak, Semra; Çayköylü, Ali; Algın, Oktay; Phillips, Mary Louise; Öngür, Dost; Moore, Constance Mary


    The aim of this study is to measure GABA levels of perisylvian cortices in schizophrenia and bipolar disorder patients, using proton magnetic resonance spectroscopy (1H-MRS). Patients with schizophrenia (n=25), bipolar I disorder (BD-I; n=28) and bipolar II disorder (BD-II; n=20) were compared with healthy controls (n=30). 1H-MRS data was acquired using a Siemens 3T whole body scanner to quantify right and left perisylvian structures' (including superior temporal lobes) GABA levels. Right perisylvian GABA values differed significantly between groups [χ2=9.62, df: 3, p=0.022]. GABA levels were significantly higher in the schizophrenia group compared with the healthy control group (p=0.002). Furthermore, Chlorpromazine equivalent doses of antipsychotics correlated with right hemisphere GABA levels (r2=0.68, p=0.006, n=33). GABA levels are elevated in the right hemisphere in patients with schizophrenia in comparison to bipolar disorder and healthy controls. The balance between excitatory and inhibitory controls over the cortical circuits may have direct relationship with GABAergic functions in auditory cortices. In addition, GABA levels may be altered by brain regions of interest, psychotropic medications, and clinical stage in schizophrenia and bipolar disorder. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Occipital GABA correlates with cognitive failures in daily life☆ (United States)

    Sandberg, Kristian; Blicher, Jakob Udby; Dong, Mia Yuan; Rees, Geraint; Near, Jamie; Kanai, Ryota


    The brain has limited capacity, and so selective attention enhances relevant incoming information while suppressing irrelevant information. This process is not always successful, and the frequency of such cognitive failures varies to a large extent between individuals. Here we hypothesised that individual differences in cognitive failures might be reflected in inhibitory processing in the sensory cortex. To test this hypothesis, we measured GABA in human visual cortex using MR spectroscopy and found a negative correlation between occipital GABA (GABA +/Cr ratio) and cognitive failures as measured by an established cognitive failures questionnaire (CFQ). For a second site in parietal cortex, no correlation between CFQ score and GABA +/Cr ratio was found, thus establishing the regional specificity of the link between occipital GABA and cognitive failures. We further found that grey matter volume in the left superior parietal lobule (SPL) correlated with cognitive failures independently from the impact of occipital GABA and together, occipital GABA and SPL grey matter volume statistically explained around 50% of the individual variability in daily cognitive failures. We speculate that the amount of GABA in sensory areas may reflect the potential capacity to selectively suppress irrelevant information already at the sensory level, or alternatively that GABA influences the specificity of neural representations in visual cortex thus improving the effectiveness of successful attentional modulation. PMID:24188817

  2. An Electrostatic Funnel in the GABA-Binding Pathway.

    Directory of Open Access Journals (Sweden)

    Timothy S Carpenter


    Full Text Available The γ-aminobutyric acid type A receptor (GABAA-R is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a 'funnel' that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site.

  3. [Pharmacological influences on the brain level and transport of GABA. II) Effect of various psychoactive drugs on brain level and uptake of GABA]. (United States)

    Gabana, M A; Varotto, M; Saladini, M; Zanchin, G; Battistin, L


    The effects of some psychoactive drugs on the level and uptake of GABA in the mouse brain was studied using well standardized procedures, mainely the silica-gel cromatography for determining the GABA content and the brain slices for measuring GABA uptake. It was found that levomepromazine, sulpiride, haloperidol and amytryptiline were without effects on the cerebral level of GABA; it was also found that these drugs do not influence the rates of uptake of GABA by mouse brain slices. Such results do indicate that the psychoactive drugs studied are without effects on the level and uptake of GABA in the brain.

  4. Reduced GABA content in the motor thalamus during effective deep brain stimulation of the subthalamic nucleus

    Directory of Open Access Journals (Sweden)

    Alessandro eStefani


    Full Text Available Deep brain stimulation (DBS of the subthalamic nucleus (STN, in Parkinson’s disease (PD patients, is a well established therapeutic option, but its mechanisms of action are only partially known. In our previous study, the clinical transitions from OFF- to ON-state were not correlated with significant changes of GABA content inside GPi or substantia nigra reticulata.Here, biochemical effects of STN-DBS have been assessed in putamen (PUT, internal pallidus (GPi, and inside the antero-ventral thalamus (VA, the key station receiving pallidothalamic fibres. In ten advanced PD patients undergoing surgery, microdialysis samples were collected before and during STN-DBS. cGMP, an index of glutamatergic transmission, was measured in GPi and PUT by radioimmunoassay, whereas GABA from VA was measured by HPLC.During clinically effective STN-DBS, we found a significant decrease in GABA extracellular concentrations in VA (- 30%. Simultaneously, cGMP extracellular concentrations were enhanced in PUT (+200% and GPi (+481%. These findings support a thalamic dis-inhibition, in turn re-establishing a more physiological corticostriatal transmission, as the source of motor improvement. They indirectly confirm the relevance of patterning (instead of mere changes of excitability and suggest that a rigid interpretation of the standard model, at least when it indicates the hyperactive indirect pathway as key feature of hypokinetic signs, is unlikely to be correct. Finally, given the demonstration of a key role of VA in inducing clinical relief, locally administration of drugs modulating GABA transmission in thalamic nuclei could become an innovative therapeutic strategy.

  5. GABA[subscript A] Receptor Downregulation in Brains of Subjects with Autism (United States)

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Thuras, Paul D.


    Gamma-aminobutyric acid A (GABA[subscript A]) receptors are ligand-gated ion channels responsible for mediation of fast inhibitory action of GABA in the brain. Preliminary reports have demonstrated altered expression of GABA receptors in the brains of subjects with autism suggesting GABA/glutamate system dysregulation. We investigated the…

  6. HPLC conditions are critical for the detection of GABA by microdialysis

    NARCIS (Netherlands)

    Rea, Kieran; Cremers, T.I.F.H.; Westerink, B.H.C.

    In microdialysis studies, neither exocytotic release of gamma-aminobutyric acid (GABA), nor the presence of GABA type B (GABA(B)) autoreceptors, have been clearly established. It was investigated whether the chromatographic separation of GABA may have contributed to discrepancies in the literature.

  7. How and why does tomato accumulate a large amount of GABA in the fruit?

    Directory of Open Access Journals (Sweden)

    Mariko eTakayama


    Full Text Available γ-Aminobutyric acid (GABA has received much attention as a health-promoting functional compound, and several GABA-enriched foods have been commercialized. In higher plants, GABA is primarily metabolized via a short pathway called the GABA shunt. The GABA shunt bypasses two steps (the oxidation of α-ketoglutarate to succinate of the tricarboxylic acid (TCA cycle via reactions catalysed by three enzymes: glutamate decarboxylase (GAD, GABA transaminase (GABA-T and succinic semialdehyde dehydrogenase (SSADH. The GABA shunt plays a major role in primary carbon and nitrogen metabolism and is an integral part of the TCA cycle under stress and non-stress conditions. Tomato is one of the major crops that accumulate a relatively high level of GABA in its fruits. The GABA levels in tomato fruits dramatically change during fruit development; the GABA levels increase from flowering to the mature green stage and then rapidly decrease during the ripening stage. Although GABA constitutes up to 50% of the free amino acids at the mature green stage, the molecular mechanism of GABA accumulation and the physiological function of GABA during tomato fruit development remain unclear. In this review, we summarize recent studies of GABA accumulation in tomato fruits and discuss the potential biological roles of GABA in tomato fruit development.

  8. Evolution of endogenous analgesia

    NARCIS (Netherlands)

    Niesters, Marieke


    Endogenous pain modulation is a complex phenomenon involved in the perception of pain. It consists of top-down inhibitory and facilitatory pathways that originate at higher sites within the central nervous system and converge at dorsal horn neurons in the spinal cord, to modulate incoming afferent

  9. Unemployment and endogenous growth

    NARCIS (Netherlands)

    van Schaik, A.B.T.M.; de Groot, H.L.F.


    In this paper we develop a two-sector endogenous growth model with a dual labour market, based on efficiency wages. Growth is driven by intentional R&D performed in the high-tech and high-wage sector. It is examined how a change in rivalry among firms affects simultaneously growth and unemployment.

  10. The Endogenous Feedback Network

    DEFF Research Database (Denmark)

    Augustenborg, Claudia Carrara


    proposals, it will first be considered the extents of their reciprocal compatibility, tentatively shaping an integrated, theoretical profile of consciousness. A new theory, the Endogenous Feedback Network (EFN) will consequently be introduced which, beside being able to accommodate the main tenets...

  11. Endogenous leadership in teams


    Huck, S; Rey Biel, P.


    In this paper we study the mechanics of ``leading by example'' in teams. Leadership is beneficial for the entire team when agents are conformists, i.e., dislike effort differentials. We also show how leadership can arise endogenously and discuss what type of leader benefits a team most.

  12. Molecular Mechanisms Underlying γ-Aminobutyric Acid (GABA) Accumulation in Giant Embryo Rice Seeds. (United States)

    Zhao, Guo-Chao; Xie, Mi-Xue; Wang, Ying-Cun; Li, Jian-Yue


    To uncover the molecular mechanisms underlying GABA accumulation in giant embryo rice seeds, we analyzed the expression levels of GABA metabolism genes and contents of GABA and GABA metabolic intermediates in developing grains and germinated brown rice of giant embryo rice 'Shangshida No. 5' and normal embryo rice 'Chao2-10' respectively. In developing grains, the higher GABA contents in 'Shangshida No. 5' were accompanied with upregulation of gene transcripts and intermediate contents in the polyamine pathway and downregulation of GABA catabolic gene transcripts, as compared with those in 'Chao2-10'. In germinated brown rice, the higher GABA contents in 'Shangshida No. 5' were parallel with upregulation of OsGAD and polyamine pathway gene transcripts and Glu and polyamine pathway intermediate contents and downregulation of GABA catabolic gene transcripts. These results are the first to indicate that polyamine pathway and GABA catabolic genes play a crucial role in GABA accumulation in giant embryo rice seeds.

  13. The effects of neuroleptics on the GABA-induced Cl- current in rat dorsal root ganglion neurons: differences between some neuroleptics. (United States)

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada


    1. Several neuroleptics inhibited the 3 microM gamma-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. 2. The IC(50) for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 microM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 microM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. 3. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. 4. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 microM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. 5. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 microM)-current. However, haloperidol and quetiapine at 100 microM inhibited the desensitization at the beginning of application. 6. Blonanserin (AD-5423) at 30 and 50 microM potentiated the GABA (3 microM)-current to 170.1+/-6.9 and 192.0+/-10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. 7. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold.

  14. The effects of neuroleptics on the GABA-induced Cl− current in rat dorsal root ganglion neurons: differences between some neuroleptics (United States)

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada


    Several neuroleptics inhibited the 3 μM γ-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. The IC50 for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 μM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 μM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 μM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 μM)-current. However, haloperidol and quetiapine at 100 μM inhibited the desensitization at the beginning of application. Blonanserin (AD-5423) at 30 and 50 μM potentiated the GABA (3 μM)-current to 170.1±6.9 and 192.0±10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold. PMID:11906969

  15. Neurosteroid regulation of GABA(A) receptors: Focus on the alpha4 and delta subunits. (United States)

    Smith, Sheryl S; Shen, Hui; Gong, Qi Hua; Zhou, Xiangping


    Neurosteroids, such as the progesterone metabolite 3alpha-OH-5alpha[beta]-pregnan-20-one (THP or [allo]pregnanolone), function as potent positive modulators of the GABA(A) receptor (GABAR) when acutely administered. However, fluctuations in the circulating levels of this steroid at puberty, across endogenous ovarian cycles, during pregnancy or following chronic stress produce periods of prolonged exposure and withdrawal, where changes in GABAR subunit composition may occur as compensatory responses to sustained levels of inhibition. A number of laboratories have demonstrated that both chronic administration of THP as well as its withdrawal transiently increase expression of the alpha4 subunit of the GABAR in several areas of the central nervous system (CNS) as well as in in vitro neuronal systems. Receptors containing this subunit are insensitive to benzodiazepine (BDZ) modulation and display faster deactivation kinetics, which studies suggest underlie hyperexcitability states. Similar increases in alpha4 expression are triggered by withdrawal from other GABA-modulatory compounds, such as ethanol and BDZ, suggesting a common mechanism. Other studies have reported puberty or estrous cycle-associated increases in delta-GABAR, the most sensitive target of these steroids which underlies a tonic inhibitory current. In the studies reported here, the effect of steroids on inhibition, which influence anxiety state and seizure susceptibility, depend not only on the subunit composition of the receptor but also on the direction of Cl(-) current generated by these target receptors. The effect of neurosteroids on GABAR function thus results in behavioral outcomes relevant for pubertal mood swings, premenstrual dysphoric disorder and catamenial epilepsy, which are due to fluctuations in endogenous steroids.

  16. GABA Metabolism and Transport: Effects on Synaptic Efficacy

    Directory of Open Access Journals (Sweden)

    Fabian C. Roth


    Full Text Available GABAergic inhibition is an important regulator of excitability in neuronal networks. In addition, inhibitory synaptic signals contribute crucially to the organization of spatiotemporal patterns of network activity, especially during coherent oscillations. In order to maintain stable network states, the release of GABA by interneurons must be plastic in timing and amount. This homeostatic regulation is achieved by several pre- and postsynaptic mechanisms and is triggered by various activity-dependent local signals such as excitatory input or ambient levels of neurotransmitters. Here, we review findings on the availability of GABA for release at presynaptic terminals of interneurons. Presynaptic GABA content seems to be an important determinant of inhibitory efficacy and can be differentially regulated by changing synthesis, transport, and degradation of GABA or related molecules. We will discuss the functional impact of such regulations on neuronal network patterns and, finally, point towards pharmacological approaches targeting these processes.

  17. Study on Flavour Volatiles of GABA Green Tea

    African Journals Online (AJOL)



    Jun 26, 2012 ... ISSN 1684–5315 ©2012 Academic Journals. Full Length Research Paper. Study on flavour volatiles of ..... GABA tea helps sleep. J. Altern. ... and pu-erh teas with dabsylation and high-performance liquid chromatography. J.

  18. Efficient Production of γ-GABA Using Recombinant E. coli Expressing Glutamate Decarboxylase (GAD) Derived from Eukaryote Saccharomyces cerevisiae. (United States)

    Xiong, Qiang; Xu, Zheng; Xu, Lu; Yao, Zhong; Li, Sha; Xu, Hong


    γ-Aminobutyric acid (γ-GABA) is a non-proteinogenic amino acid, which acts as a major regulator in the central nervous system. Glutamate decarboxylase (namely GAD, EC is known to be an ideal enzyme for γ-GABA production using L-glutamic acid as substrate. In this study, we cloned and expressed GAD gene from eukaryote Saccharomyces cerevisiae (ScGAD) in E. coli BL21(DE3). This enzyme was further purified and its optimal reaction temperature and pH were 37 °C and pH 4.2, respectively. The cofactor of ScGAD was verified to be either pyridoxal 5'-phosphate (PLP) or pyridoxal hydrochloride. The optimal concentration of either cofactor was 50 mg/L. The optimal medium for E. coli-ScGAD cultivation and expression were 10 g/L lactose, 5 g/L glycerol, 20 g/L yeast extract, and 10 g/L sodium chloride, resulting in an activity of 55 U/mL medium, three times higher than that of using Luria-Bertani (LB) medium. The maximal concentration of γ-GABA was 245 g/L whereas L-glutamic acid was near completely converted. These findings provided us a good example for bio-production of γ-GABA using recombinant E. coli expressing a GAD enzyme derived from eukaryote.

  19. Species dependent dual modulation of the benzodiazepine/GABA receptor chloride channel by dihydroergosine

    Energy Technology Data Exchange (ETDEWEB)

    Pericic, D.; Tvrdeic, A. (Rudjer Boskovic Institute, Zagreb (Yugoslavia))


    Dihydroergosine enhanced the incidence of bicuculline induced convulsions in female rats, while 100 mg/kg of dihydroergosine given to female mice made 45% convulsive dose of bicuculline to be subconvulsive. The same dose of dihydroergosine enhanced in mice the latency of bicuculline-induced convulsions. Although, in in vitro experiments dihydroergosine showed very weak ability to prevent the binding of {sup 3}H-muscimol, the drug was able to diminish and to augment the IC{sub 50} of bicuculline and GABA when added to crude synaptosomal pellet of the rat and mouse brain respectively. Lower concentrations of dihydroergosine stimulated and higher inhibited {sup 3}H-TBOB binding to the crude synaptosomal pellet of the rat brain. In the preparation of mouse brain dihydroergosine produced only inhibition of {sup 3}H-TBOB binding. Only slight quantitative differences were observed in bicuculline-induced stimulation and in GABA- and diazepam-induced inhibition of {sup 3}H-TBOB binding between the two species. The results suggest that the opposite species-dependent effects of dihydroergosine on bicuculline-induced convulsions are due to the ability of this drug to modulate species-dependently the benzodiazepine/GABA receptor chloride channel complex.

  20. Retrospective correction of frequency drift in spectral editing: The GABA editing example. (United States)

    van der Veen, Jan Willem; Marenco, Stefano; Berman, Karen F; Shen, Jun


    GABA levels can be measured using proton MRS with a two-step editing sequence. However due to the low concentration of GABA, long acquisition time is usually needed to achieve sufficient SNR to detect small differences in many psychiatric disorders. During this long scan time the frequency offset of the measured voxel can change because of magnetic field drift and patient movement. This drift will change the frequency of the editing pulse relative to that of metabolites, leading to errors in quantification. In this article we describe a retrospective method to correct for frequency drift in spectral editing. A series of reference signals for each metabolite was generated for a range of frequency offsets and then averaged together based on the history of frequency changes over the scan. These customized basis sets were used to fit the in vivo data. Our results demonstrate the effectiveness of the correction method and the remarkable robustness of a GABA editing technique with a top hat editing profile in the presence of frequency drift. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  1. GABA level, gamma oscillation, and working memory performance in schizophrenia

    Directory of Open Access Journals (Sweden)

    Chi-Ming A. Chen


    Full Text Available A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case–control pilot study (N = 24 compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC, and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7 had significantly lower amplitudes in gamma oscillations than controls (n = 9. However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16 significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia.

  2. GABA signaling and neuroactive steroids in adrenal medullary chromaffin cells

    Directory of Open Access Journals (Sweden)

    Keita eHarada


    Full Text Available GABA is produced not only in the brain, but also in endocrine cells by the two isoforms of glutamic acid decarboxylase (GAD, GAD65 and GAD67. In rat adrenal medullary chromaffin cells only GAD67 is expressed, and GABA is stored in large dense core vesicles, but not synaptic-like microvesicles. The 32/32 complex represents the majority of GABAA receptors expressed in rat and guinea pig chromaffin cells, whereas PC12 cells, an immortalized rat chromaffin cell line, express the 1 subunit as well as the 3. The expression of 3, but not 1, in PC12 cells is enhanced by glucocorticoid activity, which may be mediated by both the mineralocorticoid receptor and the glucocorticoid receptor. GABA has two actions mediated by GABAA receptors in chromaffin cells: it induces catecholamine secretion by itself and produces an inhibition of synaptically evoked secretion by a shunt effect. Allopregnanolone, a neuroactive steroid which is secreted from the adrenal cortex, produces a marked facilitation of GABAA receptor channel activity. Since there are no GABAergic nerve fibers in the adrenal medulla, GABA may function as a para/autocrine factor in the chromaffin cells. This function of GABA may be facilitated by expression of the immature isoforms of GAD and GABAA receptors and the lack of expression of plasma membrane GABA transporters. In this review, we will consider how the para/autocrine function of GABA is achieved, focusing on the structural and molecular mechanisms for GABA signaling.

  3. GABA analogues derived from 4-aminocyclopent-1-enecarboxylic acid. (United States)

    Locock, Katherine E S; Johnston, Graham A R; Allan, Robin D


    The incorporation of extra binding groups onto known ligands is a powerful tool for the development of more potent and selective agents at target sites such as the GABA receptors. In the present work we have attempted to build on the activity of the know potent GABA(A) agonist 4-ACP-3-CA and its cis and trans saturated analogues CACP and TACP. We have investigated reactions to add thiol substituents to the alpha,beta-unsaturated system of 4-ACP-3-CA. The reaction was successful with a limited number of thiols but gave products of mixed stereochemistry. The resultant thioether amino acids were screened for activity at human recombinant alpha(1)beta(2) gamma(2L) GABA(A) receptors. The most interesting derivative was the benzylthioether which acted as an antagonist with an IC(50) of 42 microM for the inhibition of a GABA EC(50) dose (50 microM). This study has shown that GABA analogues derived by thiol addition to 4-aminocyclopent-1-enecarboxylic acid display interesting antagonist activity at the alpha(1)beta(2)gamma(2L) GABA(A) receptor.

  4. Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex.

    Directory of Open Access Journals (Sweden)

    Susanna A Walter

    Full Text Available Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD responses in functional magnetic resonance imaging (fMRI is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

  5. Temporal development of GABA agonist induced alterations in ultrastructure and GABA receptor expression in cultured cerebellar granule cells

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Belhage, B; Schousboe, A


    The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays. It was f......The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays....... It was found that the cytoplasmic density of smooth endoplasmic reticulum was decreased, while the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles and coated vesicles was greatly enhanced after exposure of the cells to THIP (150 microM) for only 1 hr. In cerebellar granule cells...

  6. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan


    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  7. Endogenous growth and the environment

    NARCIS (Netherlands)

    Withagen, C.A.A.M.; Vellinga, N.


    This paper examines the relationship between environmental policy and growth, from the perspective of endogenous growth theory. In particular three standard endogenous growth models are supplemented with environmental issues, such as pollution and exhaustibility of natural resources. It is found

  8. Flavonoid Myricetin Modulates GABA(A) Receptor Activity through Activation of Ca(2+) Channels and CaMK-II Pathway. (United States)

    Zhang, Xiao Hu; Ma, Ze Gang; Rowlands, Dewi Kenneth; Gou, Yu Lin; Fok, Kin Lam; Wong, Hau Yan; Yu, Mei Kuen; Tsang, Lai Ling; Mu, Li; Chen, Lei; Yung, Wing Ho; Chung, Yiu Wa; Zhang, Bei Lin; Zhao, Hua; Chan, Hsiao Chang


    The flavonoid myricetin is found in several sedative herbs, for example, the St. John's Wort, but its influence on sedation and its possible mechanism of action are unknown. Using patch-clamp technique on a brain slice preparation, the present study found that myricetin promoted GABAergic activity in the neurons of hypothalamic paraventricular nucleus (PVN) by increasing the decay time and frequency of the inhibitory currents mediated by GABA(A) receptor. This effect of myricetin was not blocked by the GABA(A) receptor benzodiazepine- (BZ-) binding site antagonist flumazenil, but by KN-62, a specific inhibitor of the Ca(2+)/calmodulin-stimulated protein kinase II (CaMK-II). Patch clamp and live Ca(2+) imaging studies found that myricetin could increase Ca(2+) current and intracellular Ca(2+) concentration, respectively, via T- and L-type Ca(2+) channels in rat PVN neurons and hypothalamic primary culture neurons. Immunofluorescence staining showed increased phosphorylation of CaMK-II after myricetin incubation in primary culture of rat hypothalamic neurons, and the myricetin-induced CaMK-II phosphorylation was further confirmed by Western blotting in PC-12 cells. The present results suggest that myricetin enhances GABA(A) receptor activity via calcium channel/CaMK-II dependent mechanism, which is distinctively different from that of most existing BZ-binding site agonists of GABA(A) receptor.

  9. Sleep-promoting effects of a GABA/5-HTP mixture: Behavioral changes and neuromodulation in an invertebrate model. (United States)

    Hong, Ki-Bae; Park, Yooheon; Suh, Hyung Joo


    This study was to investigate the sleep promoting effects of combined γ-aminobutyric acid (GABA) and 5-hydroxytryptophan (5-HTP), by examining neuronal processes governing mRNA level alterations, as well as assessing neuromodulator concentrations, in a fruit fly model. Behavioral assays were applied to investigate subjective nighttime activity, sleep episodes, and total duration of subjective nighttime sleep of two amino acids and GABA/5-HTP mixture with caffeine treated flies. Also, real-time PCR and HPLC analysis were applied to analyze the signaling pathway. Subjective nighttime activity and sleep patterns of individual flies significantly decreased with 1% GABA treatment in conjunction with 0.1% 5-HTP treatment (psleep patterns (40%, psleep in the awake model (ptreatment (2.1 fold and 1.2 fold higher than the control, respectively) and also increased 5-HTP levels (0 h: 1.01 μg/protein, 12h: 3.45 μg/protein). In this regard, we successfully demonstrated that using a GABA/5-HTP mixture modulates subjective nighttime activity, sleep episodes, and total duration of subjective nighttime sleep to a greater extent than single administration of each amino acid, and that this modulation occurs via GABAergic and serotonergic signaling. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Saturable binding of /sup 35/S-t-butylbicyclophosphorothionate to the sites linked to the GABA receptor and the interaction with gabaergic agents

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.T.; Threlkeld, P.G.; Bymaster, F.P.; Squires, R.F.


    /sup 35/-S-t-Butylbicyclophosphorothionate (/sup 35/S-TBPS) binds in a concentration-saturable manner to specific sites on membranes from rat cerebral cortex. Using a filtration assay at 25/sup 0/C, in 250 mM NaCl, specific binding of /sup 35/S-TBPS constitutes about 84 to 94 percent of total binding, depending on radioligand concentrations. /sup 35/S-TBPS binding is optimal in the presence of NaCl or NaBr and substantially less in the presence of NaI or NaF. It is sensitive to the treatment with 0.05 percent Triton X-100 but not to repeated freezing and thawing, procedures which increase /sup 3/H-GABA binding. Pharmacological studies show that /sup 35/S-TBPS binding is strongly inhibited by GABA-A receptor agonists (e.g., GABA and muscimol) and by the noncompetitive antagonist, picrotoxin, but not the competitive antagonist, bicuculline. Compounds which enhance binding of radioactive GABA and benzodiazepines, such as the pyrazolopyridines, cartazolate and trazolate, and a diaryl-triazine, LY81067, are also potent inhibitors of /sup 35/S-TBPS binding, with LY81067 being the most effective. The effects of GABA, picrotoxin

  11. GABA agonist induced changes in ultrastructure and GABA receptor expression in cerebellar granule cells is linked to hyperpolarization of the neurons

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, G H; Schousboe, A


    GABA has been shown to exert a neurotrophic like activity by enhancing the morphological and functional maturation of neurons. Mechanisms involved in this effect of GABA are largely unknown but since GABA has been shown to mediate a hyperpolarizing action on neurons it can be assumed...... that this action might be important. In order to investigate this possibility, the ability to mimic the trophic actions of GABA of different agents known to influence the membrane potential or the GABA gated chloride channels was studied. Hence, GABA receptor expression as well as the ultrastructure of cerebellar...... granule cells were monitored after exposure of the cells in culture to either bromide, valinomycin or picrotoxin. It was found that cells which at early developmental stages (4 days in culture) were exposed to bromide or valinomycin expressed low affinity GABA receptors similar to cells treated...

  12. GABA-ergic drugs: exit stage left, enter stage right. (United States)

    Ashton, Heather; Young, Allan H


    Drugs that enhance gamma-aminobutyric acid (GABA) activity by interacting at post-synaptic GABA(A) receptors have long been used as hypnotics, sedatives, tranquillizers and anticonvulsants. In this category, benzodiazepines rapidly gained pride of place, replacing barbiturates and becoming the most commonly prescribed of all drugs in the Western world in the 1970s. However, problems such as dependence and withdrawal reactions became apparent in the 1980s, and it seemed that the usefulness of drugs with this mode of action was limited. Recently, focus has shifted to a new group of drugs with GABA-ergic actions mediated through various mechanisms not directly involving the GABA(A) receptor. These drugs include gabapentin, vigabatrin, tiagabine, lamotrigine, pregabalin and others. Although originally developed as anticonvulsants for epilepsy, they appear to have wider applications for use in affective disorders, especially bipolar depression, anxiety disorders and pain conditions. The current information on the properties and therapeutic potential of this new generation of GABA-ergic drugs is reviewed. It remains to be seen whether long-term use leads to tolerance, dependence and withdrawal or discontinuation reactions.

  13. GABA transporter-1 deficiency confers schizophrenia-like behavioral phenotypes.

    Directory of Open Access Journals (Sweden)

    Zhe Yu

    Full Text Available The mechanism underlying the pathogenesis of schizophrenia remains poorly understood. The hyper-dopamine and hypo-NMDA receptor hypotheses have been the most enduring ideas. Recently, emerging evidence implicates alterations of the major inhibitory system, GABAergic neurotransmission in the schizophrenic patients. However, the pathophysiological role of GABAergic system in schizophrenia still remains dubious. In this study, we took advantage of GABA transporter 1 (GAT1 knockout (KO mouse, a unique animal model with elevated ambient GABA, to study the schizophrenia-related behavioral abnormalities. We found that GAT1 KO mice displayed multiple behavioral abnormalities related to schizophrenic positive, negative and cognitive symptoms. Moreover, GAT1 deficiency did not change the striatal dopamine levels, but significantly enhanced the tonic GABA currents in prefrontal cortex. The GABA(A receptor antagonist picrotoxin could effectively ameliorate several behavioral defects of GAT1 KO mice. These results identified a novel function of GAT1, and indicated that the elevated ambient GABA contributed critically to the pathogenesis of schizophrenia. Furthermore, several commonly used antipsychotic drugs were effective in treating the locomotor hyperactivity in GAT1 KO mice, suggesting the utility of GAT1 KO mice as an alternative animal model for studying schizophrenia pathogenesis and developing new antipsychotic drugs.

  14. Endogenous cannabinoids and appetite. (United States)

    Kirkham, T C; Williams, C M


    Since pre-history, Cannabis sativa has been exploited for its potent and manifold pharmacological actions. Amongst the most renowned of these actions is a tendency to provoke ravenous eating. The characterization of the psychoactive principals in cannabis (exogenous cannabinoids) and, more recently, the discovery of specific brain cannabinoid receptors and their endogenous ligands (endocannabinoids) has stimulated research into the physiological roles of endocannabinoid systems. In this review, we critically discuss evidence from the literature that describe studies on animals and human subjects to support endocannabinoid involvement in the control of appetite. We describe the hyperphagic actions of the exogenous cannabinoid, Delta9-tetrahydrocannabinol, and the endogenous CB1 ligands, anandamide and 2-arachidonylglycerol, and present evidence to support a specific role of endocannabinoid systems in appetitive processes related to the incentive and reward properties of food. A case is made for more comprehensive and systematic analyses of cannabinoid actions on eating, in the anticipation of improved therapies for disorders of appetite and body weight, and a better understanding of the biopsychological processes underlying hunger.

  15. Stabilization of GABA(A) receptors at endocytic zones is mediated by an AP2 binding motif within the GABA(A) receptor β3 subunit. (United States)

    Smith, Katharine R; Muir, James; Rao, Yijian; Browarski, Marietta; Gruenig, Marielle C; Sheehan, David F; Haucke, Volker; Kittler, Josef T


    The strength of synaptic inhibition can be controlled by the stability and endocytosis of surface and synaptic GABA(A) receptors (GABA(A)Rs), but the surface receptor dynamics that underpin GABA(A)R recruitment to dendritic endocytic zones (EZs) have not been investigated. Stabilization of GABA(A)Rs at EZs is likely to be regulated by receptor interactions with the clathrin-adaptor AP2, but the molecular determinants of these associations remain poorly understood. Moreover, although surface GABA(A)R downmodulation plays a key role in pathological disinhibition in conditions such as ischemia and epilepsy, whether this occurs in an AP2-dependent manner also remains unclear. Here we report the characterization of a novel motif containing three arginine residues (405RRR407) within the GABA(A)R β3-subunit intracellular domain (ICD), responsible for the interaction with AP2 and GABA(A)R internalization. When this motif is disrupted, binding to AP2 is abolished in vitro and in rat brain. Using single-particle tracking, we reveal that surface β3-subunit-containing GABA(A)Rs exhibit highly confined behavior at EZs, which is dependent on AP2 interactions via this motif. Reduced stabilization of mutant GABA(A)Rs at EZs correlates with their reduced endocytosis and increased steady-state levels at synapses. By imaging wild-type or mutant super-ecliptic pHluorin-tagged GABA(A)Rs in neurons, we also show that, under conditions of oxygen-glucose deprivation to mimic cerebral ischemia, GABA(A)Rs are depleted from synapses in dendrites, depending on the 405RRR407 motif. Thus, AP2 binding to an RRR motif in the GABA(A)R β3-subunit ICD regulates GABA(A)R residency time at EZs, steady-state synaptic receptor levels, and pathological loss of GABA(A)Rs from synapses during simulated ischemia.

  16. Detection and distribution of endogenous steroids in human stratum corneum

    Directory of Open Access Journals (Sweden)

    Shu-Ping Tseng


    Conclusion: The results demonstrate that, with the achievable sensitivity of current analytical technology, physiological concentrations of endogenous steroids, such as hydrocortisone and cortisone, can be found in the SC of some individuals.

  17. Marlin-1, a novel RNA-binding protein associates with GABA receptors. (United States)

    Couve, Andrés; Restituito, Sophie; Brandon, Julia M; Charles, Kelly J; Bawagan, Hinayana; Freeman, Katie B; Pangalos, Menelas N; Calver, Andrew R; Moss, Stephen J


    GABA(B) receptors are heterodimeric G protein-coupled receptors that mediate slow synaptic inhibition in the central nervous system. Whereas heterodimerization between GABA(B) receptor GABA(B)R1 and GABA(B)R2 subunits is essential for functional expression, how neurons coordinate the assembly of these critical receptors remains to be established. Here we have identified Marlin-1, a novel GABA(B) receptor-binding protein that associates specifically with the GABA(B)R1 subunit in yeast, tissue culture cells, and neurons. Marlin-1 is expressed in the brain and exhibits a granular distribution in cultured hippocampal neurons. Marlin-1 binds different RNA species including the 3'-untranslated regions of both the GABA(B)R1 and GABA(B)R2 mRNAs in vitro and also associates with RNA in cultured neurons. Inhibition of Marlin-1 expression via small RNA interference technology results in enhanced intracellular levels of the GABA(B)R2 receptor subunit without affecting the level of GABA(B)R1. Together our results suggest that Marlin-1 functions to regulate the cellular levels of GABA(B) R2 subunits, which may have significant effects on the production of functional GABA(B) receptor heterodimers. Therefore, our observations provide an added level of regulation for the control of GABA(B) receptor expression and for the efficacy of inhibitory synaptic transmission.

  18. Circadian rhythms of dopamine, glutamate and GABA in the striatum and nucleus accumbens of the awake rat: modulation by light. (United States)

    Castañeda, Tamara R; de Prado, Blanca Marquez; Prieto, David; Mora, Francisco


    Using microdialysis, we investigated the circadian rhythms of the extracellular concentrations of dopamine, glutamate and gamma-aminobutyric acid (GABA) in the striatum and nucleus accumbens of the awake rat. Wistar rats were maintained in a 12 hr dark:12 hr light (12:12) cycle for 2 wk before the experiment began. The neurotransmitter levels were measured every 30 min for 30 hr in control (maintaining the 12:12 cycle) or in experimental conditions under a 24-h light period (continuous light) or under a 24-h dark interval (continuous dark). The dopamine metabolites, DOPAC and HVA, and the main serotonin metabolite, 5-HIAA, were measured along with arginine and glutamine under all conditions. In 12:12 conditions, a circadian rhythm of dopamine, glutamate and GABA was found in both the striatum and nucleus accumbens. Again under 12:12 conditions, DOPAC, HVA, 5-HIAA, and arginine, but not glutamine, fluctuated in a circadian rhythm. In the striatum under constant light conditions, there was a circadian rhythm of dopamine, glutamate, GABA, DOPAC and HVA, but not 5-HIAA. By contrast, when the rats were kept under continuous dark, dopamine and its metabolites, DOPAC and HVA (but not glutamate and GABA), did not fluctuate in a circadian rhythm. In the nucleus accumbens, under both constant light or dark conditions, no changes were found in the circadian rhythm in any of the neurotransmitters and metabolites studied. These findings show that in the striatum, dopamine but not glutamate and GABA, seem to be influenced by light. In the nucleus accumbens, however, the three neurotransmitters had a circadian rhythm, which was independent of light.

  19. The betaine/GABA transporter and betaine: roles in brain, kidney and liver

    Directory of Open Access Journals (Sweden)

    Stephen A Kempson


    Full Text Available The physiological roles of the betaine/GABA transporter (BGT1; slc6a12 are still being debated. BGT1 is a member of the solute carrier family 6 (the neurotransmitter, sodium symporter transporter family and mediates cellular uptake of betaine and GABA in a sodium- and chloride- dependent process. Most of the studies of BGT1 concern its function and regulation in the kidney medulla where its role is best understood. The conditions here are hostile due to hyperosmolarity and significant concentrations of NH4Cl and urea. To withstand the hyperosmolarity, cells trigger osmotic adaptation, involving concentration of a transcriptional factor TonEBP/NFAT5 in the nucleus, and accumulate betaine and other osmolytes. Data from renal cells in culture, primarily MDCK, revealed that transcriptional regulation of BGT1 by TonEBP/NFAT5 is relatively slow. To allow more acute control of the abundance of BGT1 protein in the plasma membrane, there is also post-translation regulation of BGT1 protein trafficking which is dependent on intracellular calcium and ATP. Further, betaine may be important in liver metabolism as a methyl donor. In fact, in the mouse the liver is the organ with the highest content of BGT1. Hepatocytes express high levels of both BGT1 and the only enzyme that can metabolize betaine, namely betaine:homocysteine –S-methyltransferase (BHMT1. The BHMT1 enzyme removes a methyl group from betaine and transfers it to homocysteine, a potential risk factor for cardiovascular disease. Finally, BGT1 has been proposed to play a role in controlling brain excitability and thereby represents a target for anticonvulsive drug development. The latter hypothesis is controversial due to very low expression levels of BGT1 relative to other GABA transporters in brain, and also the primary location of BGT1 at the surface of the brain in the leptomeninges. These issues are discussed in detail.

  20. Progesterone withdrawal reduces paired-pulse inhibition in rat hippocampus: dependence on GABA(A) receptor alpha4 subunit upregulation. (United States)

    Hsu, Fu-Chun; Smith, Sheryl S


    Withdrawal from the endogenous steroid progesterone (P) after chronic administration increases anxiety and seizure susceptibility via declining levels of its potent GABA-modulatory metabolite 3alpha-OH-5alpha-pregnan-20-one (3alpha,5alphaTHP). This 3alpha,5alpha-THP withdrawal also results in a decreased decay time constant for GABA-gated current assessed using whole cell patch-clamp techniques on pyramidal cells acutely dissociated from CA1 hippocampus. The purpose of this study was to test the hypothesis that the decreases in total integrated GABA-gated current observed at the level of the isolated pyramidal cell would be manifested as a reduced GABA inhibition at the circuit level following hormone withdrawal. Toward this end, adult, female rats were administered P via subcutaneous capsule for 3 wk using a multiple withdrawal paradigm. We then evaluated paired-pulse inhibition (PPI) of pyramidal neurons in CA1 hippocampus using extracellular recording techniques in hippocampal slices from rats 24 h after removal of the capsule (P withdrawal, P Wd). The population spike (PS) was recorded at the stratum pyramidale following homosynaptic orthodromic stimulation in the nearby stratum radiatum. The threshold for eliciting a response was decreased after P Wd, and the mean PS amplitude was significantly increased compared with control values at this time. Paired pulses with 10-ms inter-pulse intervals were then applied across an intensity range from 2 to 20 times threshold. Evaluation of paired-pulse responses showed a significant 40-50% reduction in PPI for PS recorded in the hippocampal CA1 region after P Wd, suggesting an increase in circuit excitability. At this time, enhancement of PPI by the benzodiazepine lorazepam (LZM; 10 microM) was prevented, while pentobarbital (10 microM) potentiation of PPI was comparable to control levels of response. These data are consistent with upregulation of the alpha4 subunit of the GABA(A) receptor (GABAR) as we have previously

  1. Selective mGAT2 (BGT-1) GABA Uptake Inhibitor

    DEFF Research Database (Denmark)

    Vogensen, Stine Byskov; Jørgensen, Lars; Madsen, Karsten Kirkegaard


    β-Amino acids sharing a lipophilic diaromatic side chain were synthesized and characterized pharmacologically on mouse GABA transporter subtypes mGAT1−4. The parent amino acids were also characterized. Compounds 13a, 13b, and 17b displayed more than 6-fold selectivity for mGAT2 over mGAT1. Compound...... 17b displayed anticonvulsive properties inferring a role of mGAT2 in epileptic disorders. These results provide new neuropharmacological tools and a strategy for designing subtype selective GABA transport inhibitors....

  2. Endogenous Lunar Volatiles (United States)

    McCubbin, F. M.; Liu, Y.; Barnes, J. J.; Boyce, J. W.; Day, J. M. D.; Elardo, S. M.; Hui, H.; Magna, T.; Ni, P.; Tartese, R.; hide


    The chapter will begin with an introduction that defines magmatic volatiles (e.g., H, F, Cl, S) versus geochemical volatiles (e.g., K, Rb, Zn). We will discuss our approach of understanding both types of volatiles in lunar samples and lay the ground work for how we will determine the overall volatile budget of the Moon. We will then discuss the importance of endogenous volatiles in shaping the "Newer Views of the Moon", specifically how endogenous volatiles feed forward into processes such as the origin of the Moon, magmatic differentiation, volcanism, and secondary processes during surface and crustal interactions. After the introduction, we will include a re-view/synthesis on the current state of 1) apatite compositions (volatile abundances and isotopic compositions); 2) nominally anhydrous mineral phases (moderately to highly volatile); 3) volatile (moderately to highly volatile) abundances in and isotopic compositions of lunar pyroclastic glass beads; 4) volatile (moderately to highly volatile) abundances in and isotopic compositions of lunar basalts; 5) volatile (moderately to highly volatile) abundances in and isotopic compositions of melt inclusions; and finally 6) experimental constraints on mineral-melt partitioning of moderately to highly volatile elements under lunar conditions. We anticipate that each section will summarize results since 2007 and focus on new results published since the 2015 Am Min review paper on lunar volatiles [9]. The next section will discuss how to use sample abundances of volatiles to understand the source region and potential caveats in estimating source abundances of volatiles. The following section will include our best estimates of volatile abundances and isotopic compositions (where permitted by available data) for each volatile element of interest in a number of important lunar reservoirs, including the crust, mantle, KREEP, and bulk Moon. The final section of the chapter will focus upon future work, outstanding questions

  3. A Mechanistic Link from GABA to Cortical Architecture and Perception. (United States)

    Kolasinski, James; Logan, John P; Hinson, Emily L; Manners, Daniel; Divanbeighi Zand, Amir P; Makin, Tamar R; Emir, Uzay E; Stagg, Charlotte J


    Understanding both the organization of the human cortex and its relation to the performance of distinct functions is fundamental in neuroscience. The primary sensory cortices display topographic organization, whereby receptive fields follow a characteristic pattern, from tonotopy to retinotopy to somatotopy [1]. GABAergic signaling is vital to the maintenance of cortical receptive fields [2]; however, it is unclear how this fine-grain inhibition relates to measurable patterns of perception [3, 4]. Based on perceptual changes following perturbation of the GABAergic system, it is conceivable that the resting level of cortical GABAergic tone directly relates to the spatial specificity of activation in response to a given input [5-7]. The specificity of cortical activation can be considered in terms of cortical tuning: greater cortical tuning yields more localized recruitment of cortical territory in response to a given input. We applied a combination of fMRI, MR spectroscopy, and psychophysics to substantiate the link between the cortical neurochemical milieu, the tuning of cortical activity, and variability in perceptual acuity, using human somatosensory cortex as a model. We provide data that explain human perceptual acuity in terms of both the underlying cellular and metabolic processes. Specifically, higher concentrations of sensorimotor GABA are associated with more selective cortical tuning, which in turn is associated with enhanced perception. These results show anatomical and neurochemical specificity and are replicated in an independent cohort. The mechanistic link from neurochemistry to perception provides a vital step in understanding population variability in sensory behavior, informing metabolic therapeutic interventions to restore perceptual abilities clinically. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  4. Differential sensitivity of two insect GABA-gated chloride channels to dieldrin, fipronil and picrotoxinin


    Le Corronch, Hervé; Alix, Philippe; Hue, B.


    In the central nervous system of both vertebrates and invertebrates inhibitory neurotransmission is mainly achieved through activation of gamma-aminobutyric acid (GABA) receptors. Extensive studies have established the structural and pharmacological properties of vertebrate GABA receptors. Although the vast majority of insect GABA-sensitive responses share some properties with vertebrate GABAA receptors, peculiar pharmacological properties of these receptors led us to think that several GABA-...

  5. Endogenous Fertility and Development Traps with Endogenous Lifetime

    Directory of Open Access Journals (Sweden)

    Luciano Fanti


    Full Text Available We extend the literature on endogenous lifetime and economic growth by Chakraborty (2004 and Bunzel and Qiao (2005 to endogenous fertility. We show that development traps due to underinvestments in health cannot appear when fertility is an economic decision variable and the costs of children are represented by a constant fraction of the parents' income used for their upbringing.

  6. d Subunit-Containing GABA[subscript A] Receptor Prevents Overgeneralization of Fear in Adult Mice (United States)

    Zhang, Wen-Hua; Zhou, Jin; Pan, Han-Qing; Wang, Xiao-Yang; Liu, Wei-Zhu; Zhang, Jun-Yu; Yin, Xiao-Ping; Pan, Bing-Xing


    The role of d subunit-containing GABA[subscript A] receptor (GABA[subscript A](d)R) in fear generalization is uncertain. Here, by using mice with or without genetic deletion of GABA[subscript A](d)R and using protocols in which the conditioned tone stimuli were cross presented with different nonconditioned stimuli, we observed that when the two…

  7. Glial GABA Transporters as Modulators of Inhibitory Signalling in Epilepsy and Stroke

    DEFF Research Database (Denmark)

    Lie, Maria E K; Al-Khawaja, Anas; Damgaard, Maria


    . An increase in tonic inhibition may, however, also be obtained indirectly by inhibiting glial GABA transporters (GATs). These are sodium-coupled membrane transport proteins that normally act to terminate GABA neurotransmitter action by taking up GABA into surrounding astrocytes. The aim of the review...

  8. Hippocampal GABA transporter distribution in patients with temporal lobe epilepsy and hippocampal sclerosis

    NARCIS (Netherlands)

    Schijns, O.; Karaca, U.; Andrade, P.; Nijs, L. de; Kusters, B.; Peeters, A.; Dings, J.; Pannek, H.; Ebner, A.; Rijkers, K.; Hoogland, G.


    PURPOSE: To determine hippocampal expression of neuronal GABA-transporter (GAT-1) and glial GABA-transporter (GAT-3) in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). METHODS: Hippocampal sections were immunohistochemically stained for GABA-transporter 1 and

  9. Gephyrin-independent GABA(AR mobility and clustering during plasticity.

    Directory of Open Access Journals (Sweden)

    Fumihiro Niwa

    Full Text Available The activity-dependent modulation of GABA-A receptor (GABA(AR clustering at synapses controls inhibitory synaptic transmission. Several lines of evidence suggest that gephyrin, an inhibitory synaptic scaffold protein, is a critical factor in the regulation of GABA(AR clustering during inhibitory synaptic plasticity induced by neuronal excitation. In this study, we tested this hypothesis by studying relative gephyrin dynamics and GABA(AR declustering during excitatory activity. Surprisingly, we found that gephyrin dispersal is not essential for GABA(AR declustering during excitatory activity. In cultured hippocampal neurons, quantitative immunocytochemistry showed that the dispersal of synaptic GABA(ARs accompanied with neuronal excitation evoked by 4-aminopyridine (4AP or N-methyl-D-aspartic acid (NMDA precedes that of gephyrin. Single-particle tracking of quantum dot labeled-GABA(ARs revealed that excitation-induced enhancement of GABA(AR lateral mobility also occurred before the shrinkage of gephyrin clusters. Physical inhibition of GABA(AR lateral diffusion on the cell surface and inhibition of a Ca(2+ dependent phosphatase, calcineurin, completely eliminated the 4AP-induced decrease in gephyrin cluster size, but not the NMDA-induced decrease in cluster size, suggesting the existence of two different mechanisms of gephyrin declustering during activity-dependent plasticity, a GABA(AR-dependent regulatory mechanism and a GABA(AR-independent one. Our results also indicate that GABA(AR mobility and clustering after sustained excitatory activity is independent of gephyrin.

  10. Systematic analysis of γ-aminobutyric acid (GABA) metabolism and function in the social amoeba Dictyostelium discoideum. (United States)

    Wu, Yuantai; Janetopoulos, Chris


    While GABA has been suggested to regulate spore encapsulation in the social amoeba Dictyostelium discoideum, the metabolic profile and other potential functions of GABA during development remain unclear. In this study, we investigated the homeostasis of GABA metabolism by disrupting genes related to GABA metabolism and signaling. Extracellular levels of GABA are tightly regulated during early development, and GABA is generated by the glutamate decarboxylase, GadB, during growth and in early development. However, overexpression of the prespore-specific homologue, GadA, in the presence of GadB reduces production of extracellular GABA. Perturbation of extracellular GABA levels delays the process of aggregation. Cytosolic GABA is degraded by the GABA transaminase, GabT, in the mitochondria. Disruption of a putative vesicular GABA transporter (vGAT) homologue DdvGAT reduces secreted GABA. We identified the GABAB receptor-like family member GrlB as the major GABA receptor during early development, and either disruption or overexpression of GrlB delays aggregation. This delay is likely the result of an abolished pre-starvation response and late expression of several "early" developmental genes. Distinct genes are employed for GABA generation during sporulation. During sporulation, GadA alone is required for generating GABA and DdvGAT is likely responsible for GABA secretion. GrlE but not GrlB is the GABA receptor during late development.

  11. Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses

    Directory of Open Access Journals (Sweden)

    E. Popova


    Full Text Available In the vertebrate retina, visual signals are segregated into parallel ON and OFF pathways, which provide information for light increments and decrements. The segregation is first evident at the level of the ON and OFF bipolar cells in distal retina. The activity of large populations of ON and OFF bipolar cells is reflected in the b- and d-waves of the diffuse electroretinogram (ERG. The role of gamma-aminobutyric acid (GABA, acting through ionotropic GABA receptors in shaping the ON and OFF responses in distal retina, is a matter of debate. This review summarized current knowledge about the types of the GABAergic neurons and ionotropic GABA receptors in the retina as well as the effects of GABA and specific GABAA and GABAC receptor antagonists on the activity of the ON and OFF bipolar cells in both nonmammalian and mammalian retina. Special emphasis is put on the effects on b- and d-waves of the ERG as a useful tool for assessment of the overall function of distal retinal ON and OFF channels. The role of GABAergic system in establishing the ON-OFF asymmetry concerning the time course and absolute and relative sensitivity of the ERG responses under different conditions of light adaptation in amphibian retina is also discussed.

  12. Saturable binding of /sup 35/S-t-butylbicyclophosphorothionate to the sites linked to the GABA receptor and the interaction with gabaergic agents

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.T.; Threlkeld, P.G.; Bymaster, F.P.; Squires, R.F.


    /sup 35/S-t-Butylbicyclophosphorothionate (/sup 35/S-TBPS) binds in a concentration-saturable manner to specific sites on membranes from rat cerebral cortex. Using a filtration assay at 25/sup 0/C, in 250 mM NaCl, specific binding of /sup 35/S-TBPS constitutes about 84 to 94 percent of total binding, depending on radioligand concentrations. /sup 35/S-TBPS binding is optimal in the presence of NaCl or NaBr and substantially less in the presence of NaI or NaF. It is sensitive to the treatment with 0.05 percent Triton X-100 but not to repeated freezing and thawing, procedures which increase /sup 3/H-GABA binding. Pharmacological studies show that /sup 35/S-TBPS binding is strongly inhibited by GABA-A receptor agonists (e.g., GABA and muscimol) and by the noncompetitive antagonist, picrotoxin, but not the competitive antagonist, bicuculline. Compounds which enhance binding of radioactive GABA and benzodiazepines, such as the pyrazolopyridines, cartazolate and tracazolate, and a diaryltriazine, LY81067, are also potent inhibitors of /sup 35/S-TBPS binding, with LY81067 being the most effective. The effects of GABA, picrotoxin and LY81067 on the saturable binding of /sup 35/S-TBPS in cortical membranes are compared. The present findings are consistent with the interpretation that /sup 35/S-TBPS bind at or near the picrotoxin-sensitive anion recognition sites of the GABA/benzodiazepine/picrotoxin receptor complex.

  13. An autonomous circadian clock in the inner mouse retina regulated by dopamine and GABA.

    Directory of Open Access Journals (Sweden)

    Guo-Xiang Ruan


    Full Text Available The influence of the mammalian retinal circadian clock on retinal physiology and function is widely recognized, yet the cellular elements and neural regulation of retinal circadian pacemaking remain unclear due to the challenge of long-term culture of adult mammalian retina and the lack of an ideal experimental measure of the retinal circadian clock. In the current study, we developed a protocol for long-term culture of intact mouse retinas, which allows retinal circadian rhythms to be monitored in real time as luminescence rhythms from a PERIOD2::LUCIFERASE (PER2::LUC clock gene reporter. With this in vitro assay, we studied the characteristics and location within the retina of circadian PER2::LUC rhythms, the influence of major retinal neurotransmitters, and the resetting of the retinal circadian clock by light. Retinal PER2::LUC rhythms were routinely measured from whole-mount retinal explants for 10 d and for up to 30 d. Imaging of vertical retinal slices demonstrated that the rhythmic luminescence signals were concentrated in the inner nuclear layer. Interruption of cell communication via the major neurotransmitter systems of photoreceptors and ganglion cells (melatonin and glutamate and the inner nuclear layer (dopamine, acetylcholine, GABA, glycine, and glutamate did not disrupt generation of retinal circadian PER2::LUC rhythms, nor did interruption of intercellular communication through sodium-dependent action potentials or connexin 36 (cx36-containing gap junctions, indicating that PER2::LUC rhythms generation in the inner nuclear layer is likely cell autonomous. However, dopamine, acting through D1 receptors, and GABA, acting through membrane hyperpolarization and casein kinase, set the phase and amplitude of retinal PER2::LUC rhythms, respectively. Light pulses reset the phase of the in vitro retinal oscillator and dopamine D1 receptor antagonists attenuated these phase shifts. Thus, dopamine and GABA act at the molecular level of PER

  14. Withdrawal properties of a neuroactive steroid: implications for GABA(A) receptor gene regulation in the brain and anxiety behavior. (United States)

    Smith, Sheryl S


    Early work in the field established that the 5 alpha-reduced metabolite of progesterone 3 alpha-OH-5 alpha-pregnan-20-one (allopregnanolone or 3 alpha,5 alpha-THP) is a potent positive modulator of the GABA(A) receptor (GABAR), the receptor mediating the effects of the primary inhibitory transmitter in the brain. This steroid acts in a manner similar to sedative drugs, such as the barbiturates, both in terms of potentiating GABA-induced inhibition in vitro and in behavioral assays, by reducing anxiety and seizure susceptibility. Because sedative compounds exhibit withdrawal properties that result in behavioral hyperexcitability, our laboratory has more recently investigated the effect of prolonged application and rapid removal (i.e. 'withdrawal') of this steroid, administered in vivo to female rats. Withdrawal from 3 alpha,5 alpha-THP produces a state of increased anxiety and lowered seizure threshold, similar to withdrawal from other GABA-modulatory drugs such as the benzodiazepines and alcohol. Hormone withdrawal also produced increases in the alpha 4-containing GABAR, an effect correlated with insensitivity of the GABAR to modulation by the benzodiazepine class of tranquilizers, as would normally occur under control conditions. In addition, changes in intrinsic channel properties, including a marked acceleration in the decay rate was also observed as a result of declining levels of 3 alpha,5 alpha-THP. Such a change would result in less inhibitory total current, and the resulting increase in neuronal excitability could then underlie the observed behavioral excitability following hormone withdrawal. These results suggest that actions of this steroid on a traditional transmitter receptor in the brain lead to alterations in GABAR subunit composition that result in changes in the intrinsic channel properties of the receptor and behavioral excitability. These results may have implications for endogenous fluctuations in this hormone which may accompany premenstrual

  15. Neonatal Nicotine Exposure Increases Excitatory Synaptic Transmission and Attenuates Nicotine-stimulated GABA release in the Adult Rat Hippocampus (United States)

    Damborsky, Joanne C.; Griffith, William H.; Winzer-Serhan, Ursula H.


    Developmental exposure to nicotine has been linked to long-lasting changes in synaptic transmission which may contribute to behavioral abnormalities seen in offspring of women who smoke during pregnancy. Here, we examined the long-lasting effects of developmental nicotine exposure on glutamatergic and GABAergic neurotransmission, and on acute nicotine-induced glutamate and GABA release in the adult hippocampus, a structure important in cognitive and emotional behaviors. We utilized a chronic neonatal nicotine treatment model to administer nicotine (6 mg/kg/day) to rat pups from postnatal day (P) 1–7, a period that falls developmentally into the third human trimester. Using whole-cell voltage clamp recordings from CA1 pyramidal neurons in hippocampal slices, we measured excitatory and inhibitory postsynaptic currents in neonatally control- and nicotine-treated young adult males. Neonatal nicotine exposure significantly increased AMPA receptor-mediated spontaneous and evoked excitatory signaling, with no change in glutamate release probability in adults. Conversely, there was no increase in spontaneous GABAergic neurotransmission in nicotine-males. Chronic neonatal nicotine treatment had no effect on acute nicotine-stimulated glutamate release in adults, but acute nicotine-stimulated GABA release was significantly attenuated. Thus, neonatal nicotine exposure results in a persistent net increase in excitation and a concurrent loss of nicotinic acetylcholine receptor (nAChR)-mediated regulation of presynaptic GABA but not glutamate release, which would exacerbate excitation following endogenous or exogenous nAChR activation. Our data underscore an important role for nAChRs in hippocampal excitatory synapse development, and suggest selective long-term changes at specific presynaptic nAChRs which together could explain some of the behavioral abnormalities associated with maternal smoking. PMID:24950455

  16. GABAagent: a system for integrating data on GABA receptors. (United States)

    Rachedi, A; Rebhan, M; Xue, H


    Scientific data pertaining to GABA receptors, which are of medical importance, are widely scattered throughout numerous heterogeneous Internet resources. This situation has made the integrated acquisition of such data difficult and substantially time consuming even for researchers who are Internet aficionados. Thus, there exists a genuine need for the development of Internet applications, such as GABAagent, which provide efficient and timely access to concise and integrated information. We report here the establishment of a novel server (GABAagent) which has been written in Perl script, and which is freely accessible through the Internet. GABAagent is designed to assist researchers in retrieving focused and integrated information related to GABA receptors from various public domain databases. GABAagent relies on server-side flat-file databases that have been created through data mining from Internet sources such as the PubMed, DDBJ, SWISS-PROT and TrEMBL, in addition to the many World Wide Web (Web) sites which are accessible through Excite (E-Web). These warehouse databases are regularly updated and contain among other things, information concerning: (i) GABA receptor publications, (ii) DNA and protein sequences and (iii) the contents of related E-Web sites along with their addresses. Our system also provides hard links to the above-mentioned Web sites and E-Web sites; the feature which adds to it the character of virtual federation type of database. The current version of GABAagent provides two user-friendly services. The first is a search engine possessing intelligent query reformulation support (GABAengine), the second an elaborate email alert service was designed into the system (GABAalert). The GABAengine allows the user to search server-side databases exclusively for GABA receptor-related queries. Whereas, GABAalert allows the user, by means of subscription, to receive immediate and/or monthly updates automatically. GABAagent is freely accessible at the

  17. Inhibition of L-glutamate and GABA synaptosome uptake by crotoxin, the major neurotoxin from Crotalus durissus terrificus venom

    Directory of Open Access Journals (Sweden)

    A.L. Cecchini


    Full Text Available This paper describes a brief study on the crotoxin mechanism of action, regarding the transport of GABA and L-glutamate in rats cortico-cerebral synaptosomes and in heterologous systems, such as COS-7 cells expressing gabaergic transporters, and C6 glioma cells and Xenopus oocytes expressing glutamatergic transporters. Crotoxin concentrations over 1 µM caused an inhibitory effect of ³H-L-glutamate and ³H-GABA, and reversibly inhibited L-glutamate uptake by C6 glioma cells. When COS-7 cells were assayed, no inhibition of the ³H-GABA transport could be evidenced. Crotoxin kept its inhibitory effect on neurotransmitters uptake even when Ca2+ ions were removed from the medium, therefore, independently of its PLA2 activity. In addition, high concentrations (2 mM of BPB did not avoid the action of crotoxin on the neurotransmitters uptake. Crotoxin also inhibited ³H-L-glutamate, independently on Na+ channel blockade by TTX. In addition, an evaluation of the lactic dehydrogenase activity indicated that uptake inhibition does not involve a hydrolytic action of crotoxin upon the membrane. We may also suggest that crotoxin acts, at least partially, altering the electrogenic equilibrium, as evidenced by confocal microscopy, when a fluorescent probe was used to verify cell permeability on C6 glioma cells in presence of crotoxin.

  18. Spatial distributions of GABA receptors and local inhibition of Ca2+ transients studied with GABA uncaging in the dendrites of CA1 pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yuya Kanemoto

    Full Text Available GABA (γ-amino-butylic acid-mediated inhibition in the dendrites of CA1 pyramidal neurons was characterized by two-photon uncaging of a caged-GABA compound, BCMACM-GABA, and one-photon uncaging of RuBi-GABA in rat hippocampal slice preparations. Although we found that GABA(A-mediated currents were diffusely distributed along the dendrites, currents elicited at the branch points of the apical dendritic trunk were approximately two times larger than those elsewhere in the dendrite. We examined the inhibitory action of the GABA-induced currents on Ca(2+ transients evoked with a single back-propagating action potential (bAP in oblique dendrites. We found that GABA uncaging selectively inhibited the Ca(2+ transients in the region adjacent (20 µm. Our data indicate that GABA inhibition results in spatially confined inhibition of Ca(2+ transients shortly after bAP, and suggest that this effect is particularly potent at the dendritic branch points where GABA receptors cluster.

  19. A fluorescence-coupled assay for gamma aminobutyric acid (GABA reveals metabolic stress-induced modulation of GABA content in neuroendocrine cancer.

    Directory of Open Access Journals (Sweden)

    Joseph E Ippolito

    Full Text Available Pathways involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA have been implicated in the pathogenesis of high grade neuroendocrine (NE neoplasms as well as neoplasms from a non-NE lineage. Using The Cancer Genome Atlas, overexpression of the GABA synthetic enzyme, glutamate decarboxylase 1 (GAD1, was found to be associated with decreased disease free-survival in prostate adenocarcinoma and decreased overall survival in clear cell renal cell carcinomas. Furthermore, GAD1 was found to be expressed in castrate-resistant prostate cancer cell lines, but not androgen-responsive cell lines. Using a novel fluorescence-coupled enzymatic microplate assay for GABA mediated through reduction of resazurin in a prostate neuroendocrine carcinoma (PNEC cell line, acid microenvironment-induced stress increased GABA levels while alkaline microenvironment-induced stress decreased GABA through modulation of GAD1 and glutamine synthetase (GLUL activities. Moreover, glutamine but not glucose deprivation decreased GABA through modulation of GLUL. Consistent with evidence in prokaryotic and eukaryotic organisms that GABA synthesis mediated through GAD1 may play a crucial role in surviving stress, GABA may be an important mediator of stress survival in neoplasms. These findings identify GABA synthesis and metabolism as a potentially important pathway for regulating cancer cell stress response as well as a potential target for therapeutic strategies.

  20. GABA (γ-aminobutyric acid production, antioxidant activity in some germinated dietary seeds and the effect of cooking on their GABA content

    Directory of Open Access Journals (Sweden)

    Kasarin TIANSAWANG


    Full Text Available Abstract Germinated grains have been known as sources of Gamma-aminobutyric acid (GABA that provide beneficial effects for human health. This study was aimed to investigate GABA production, dietary fiber, antioxidant activity, and the effect of cooking on GABA loss in germinated legumes and sesame. The highest GABA content was found in germinated mung bean, (0.8068 g kg-1, 24 h incubation followed by germinated soybean, germinated black bean and soaked sesame. Beside GABA, dietary fiber content also increased in all grains during germination where the insoluble dietary fiber fractions were always found in higher proportions to soluble dietary fiber fractions. Our results also confirmed that germinated mung bean is a rich source of GABA and dietary fibers. Microwave cooking resulted in the smallest loss of GABA in mung bean and sesame, while steaming led to the least GABA content loss in soybean and black bean. Therefore microwave cooking and steaming are the most recommended cooking processes to preserve GABA in germinated legumes and sesame.

  1. Immunocytochemical mapping of an RDL-like GABA receptor subunit and of GABA in brain structures related to learning and memory in the cricket Acheta domesticus. (United States)

    Strambi, C; Cayre, M; Sattelle, D B; Augier, R; Charpin, P; Strambi, A


    The distribution of putative RDL-like GABA receptors and of gamma-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx. Weaker immunostaining was detected in the distal part of the peduncle and in the alpha and beta lobes. The dorso- and ventrolateral protocerebrum neuropils appeared rich in RDL-like GABA receptors. Staining was also detected in the glomeruli of the antennal lobe, as well as in the ellipsoid body of the central complex. Many neurons clustered in groups exhibit GABA-like immunoreactivity. Tracts that were strongly immunostained innervated both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and ventrolateral protocerebrum were also rich in GABA-like immunoreactivity. The data demonstrated a good correlation between the distribution of the GABA-like and of the RDL-like GABA receptor immunoreactivity. The prominent distribution of RDL-like GABA receptor subunits, in particular areas of mushroom bodies and antennal lobes, underlines the importance of inhibitory signals in information processing in these major integrative centers of the insect brain.

  2. Endogenous pancreatic polypeptide in different vascular beds

    DEFF Research Database (Denmark)

    Henriksen, J H; Schwartz, Tania; Bülow, J B


    The plasma concentration of pancreatic polypeptide (PP-like immunoreactivity) was measured in different vascular beds in order to determine regional kinetics of endogenous PP in fasting, supine subjects with normal or moderately decreased kidney function. Patients with kidney disease (n = 10) had...... concentration (r = 0.70, P less than 0.01). Hepatic venous PP was significantly higher than systemic PP in both controls and patients with kidney disease (P less than 0.001, n = 15). The values were positively correlated (r = 0.98, P less than 0.001; slope = 1.37 +/- 0.05, P less than 0.001), indicating...

  3. GABA regulates the rat hypothalamic-pituitary-adrenocortical axis via different GABA-A receptor alpha-subtypes

    DEFF Research Database (Denmark)

    Mikkelsen, Jens D; Bundzikova, Jana; Larsen, Marianne Hald


    The control of the corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) is balanced by excitatory and inhibitory inputs. The GABA-A receptor, which is a major target for the inhibitory control, is composed of five subunits. The presence of an alpha(1)-, ...

  4. Astrocytic GABA transporter activity modulates excitatory neurotransmission

    DEFF Research Database (Denmark)

    Boddum, Kim; Jensen, Thomas P.; Magloire, Vincent


    Astrocytes are ideally placed to detect and respond to network activity. They express ionotropic and metabotropic receptors, and can release gliotransmitters. Astrocytes also express transporters that regulate the extracellular concentration of neurotransmitters. Here we report a previously unrec...

  5. Proteolysis controls endogenous substance P levels.

    Directory of Open Access Journals (Sweden)

    Andrew J Mitchell

    Full Text Available Substance P (SP is a prototypical neuropeptide with roles in pain and inflammation. Numerous mechanisms regulate endogenous SP levels, including the differential expression of SP mRNA and the controlled secretion of SP from neurons. Proteolysis has long been suspected to regulate extracellular SP concentrations but data in support of this hypothesis is scarce. Here, we provide evidence that proteolysis controls SP levels in the spinal cord. Using peptidomics to detect and quantify endogenous SP fragments, we identify the primary SP cleavage site as the C-terminal side of the ninth residue of SP. If blocking this pathway increases SP levels, then proteolysis controls SP concentration. We performed a targeted chemical screen using spinal cord lysates as a proxy for the endogenous metabolic environment and identified GM6001 (galardin, ilomastat as a potent inhibitor of the SP(1-9-producing activity present in the tissue. Administration of GM6001 to mice results in a greater-than-three-fold increase in the spinal cord levels of SP, which validates the hypothesis that proteolysis controls physiological SP levels.

  6. GABA(A) receptor physiology and its relationship to the mechanism of action of the 1,5-benzodiazepine clobazam. (United States)

    Sankar, Raman


    Clobazam was initially developed in the early 1970s as a nonsedative anxiolytic agent, and is currently available as adjunctive therapy for epilepsy and anxiety disorders in more than 100 countries. In October 2011, clobazam (Onfi™; Lundbeck Inc., Deerfield, IL, USA) was approved by the US FDA for use as adjunctive therapy for the treatment of seizures associated with Lennox-Gastaut syndrome in patients aged 2 years and older. It is a long-acting 1,5-benzodiazepine whose structure distinguishes it from the classic 1,4-benzodiazepines, such as diazepam, lorazepam and clonazepam. Clobazam is well absorbed, with peak concentrations occurring linearly 1-4 hours after administration. Both clobazam and its active metabolite, N-desmethylclobazam, are metabolized in the liver via the cytochrome P450 pathway. The mean half-life of N-desmethylclobazam (67.5 hours) is nearly double the mean half-life of clobazam (37.5 hours). Clobazam was synthesized with the anticipation that its distinct chemical structure would provide greater efficacy with fewer benzodiazepine-associated adverse effects. Frequently reported adverse effects of clobazam therapy include dizziness, sedation, drowsiness and ataxia. Evidence gathered from approximately 50 epilepsy clinical trials in adults and children indicated that the sedative effects observed with clobazam treatment were less severe than those reported with 1,4-benzodiazepines. In several studies of healthy volunteers and patients with anxiety, clobazam appeared to enhance participants' performance in cognitive tests, further distinguishing it from the 1,4-benzodiazepines. The anxiolytic and anticonvulsant effects of clobazam are associated with allosteric activation of the ligand-gated GABA(A) receptor. GABA(A) receptors are found extensively throughout the CNS, occurring synaptically and extrasynaptically. GABA(A) receptors are composed of five protein subunits, two copies of a single type of α subunit, two copies of one type of

  7. The role of GABA in the regulation of GnRH neurons

    Directory of Open Access Journals (Sweden)

    Miho eWatanabe


    Full Text Available Gonadotropin-releasing hormone (GnRH neurons form the final common pathway for the central regulation of reproduction. Gamma-amino butyric acid (GABA has long been implicated as one of the major players in the regulation of GnRH neurons. Although GABA is typically an inhibitory neurotransmitter in the mature adult central nervous system, most mature GnRH neurons show the unusual characteristic of being excited by GABA. While many reports have provided much insight into the contribution of GABA to the activity of GnRH neurons, the precise physiological role of the excitatory action of GABA on GnRH neurons remains elusive. This brief review presents the current knowledge of the role of GABA signaling in GnRH neuronal activity. We also discuss the modulation of GABA signaling by neurotransmitters and neuromodulators and the functional consequence of GABAergic inputs to GnRH neurons in both the physiology and pathology of reproduction.

  8. Selected Gamma Aminobutyric Acid (GABA Esters may Provide Analgesia for Some Central Pain Conditions

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    Joel S. Goldberg


    Full Text Available Central pain is an enigmatic, intractable condition, related to destruction of thalamic areas, resulting in likely loss of inhibitory synaptic transmission mediated by GABA. It is proposed that treatment of central pain, a localized process, may be treated by GABA supplementation, like Parkinson’s disease and depression. At physiologic pH, GABA exists as a zwitterion that is poorly permeable to the blood brain barrier (BBB. Because the pH of the cerebral spinal fluid (CSF is acidic relative to the plasma, ion trapping may allow a GABA ester prodrug to accumulate and be hydrolyzed within the CSF. Previous investigations with ester local anesthetics may be applicable to some GABA esters since they are weak bases, hydrolyzed by esterases and cross the BBB. Potential non-toxic GABA esters are discussed. Many GABA esters were investigated in the 1980s and it is hoped that this paper may spark renewed interest in their development.

  9. γ-Aminobutyric acid (GABA) oral rinse reduces capsaicin-induced burning mouth pain sensation

    DEFF Research Database (Denmark)

    Zhang, Yang; Wang, Kelun; Arendt-Nielsen, Lars


    BACKGROUND: In burning mouth patients, analgesia after oral administration of clonazepam may result from modulation of peripheral γ-aminobutyric acid (GABA) receptors. METHODS: The effect of oral administration of test solutions (water, 0.5 mol/L or 0.05 mol/L GABA, 1% lidocaine) was investigated...... application on the tongue evoked burning pain with a peak of 4.8/10, and significantly increased CDT and MDT while significantly decreasing WDT, HPT, and MPT. The VASAUC was significantly smaller after oral rinse with 0.05 mol/L GABA, 0.5 mol/L GABA, and 1% lidocaine than after oral rinse with water. Rinse...... of GABA. CONCLUSIONS: Capsaicin-induced burning tongue pain and decreases in WDT and HPT can be ameliorated by rinsing the mouth with lidocaine and GABA solutions. SIGNIFICANCE: Rinsing the mouth with an oral GABA containing solution ameliorated burning pain and increased heat sensitivity produced...

  10. Acute desensitization of presynaptic GABA(B)-mediated inhibition and induction of epileptiform discharges in the neonatal rat hippocampus

    NARCIS (Netherlands)

    Tosetti, P; Bakels, R; Colin-Le Brun, [No Value; Ferrand, N; Gaiarsa, JL; Caillard, O

    The consequences of sustained activation of GABA(B) receptors on GABA(B)-mediated inhibition and network activity were investigated in the neonatal rat hippocampus using whole-cell and extracellular field recordings. GABA(B)-mediated presynaptic control of gamma-aminobutyric acid (GABA) release

  11. Different subtypes of GABA-A receptors are expressed in human, mouse and rat T lymphocytes.

    Directory of Open Access Journals (Sweden)

    Suresh K Mendu

    Full Text Available γ-Aminobutyric acid (GABA is the most prominent neuroinhibitory transmitter in the brain, where it activates neuronal GABA-A receptors (GABA-A channels located at synapses and outside of synapses. The GABA-A receptors are primary targets of many clinically useful drugs. In recent years, GABA has been shown to act as an immunomodulatory molecule. We have examined in human, mouse and rat CD4(+ and CD8(+ T cells which subunit isoforms of the GABA-A channels are expressed. The channel physiology and drug specificity is dictated by the GABA-A receptor subtype, which in turn is determined by the subunit isoforms that make the channel. There were 5, 8 and 13 different GABA-A subunit isoforms identified in human, mouse and rat CD4(+ and CD8(+ T cells, respectively. Importantly, the γ2 subunit that imposes benzodiazepine sensitivity on the GABA-A receptors, was only detected in the mouse T cells. Immunoblots and immunocytochemistry showed abundant GABA-A channel proteins in the T cells from all three species. GABA-activated whole-cell transient and tonic currents were recorded. The currents were inhibited by picrotoxin, SR95531 and bicuculline, antagonists of GABA-A channels. Clearly, in both humans and rodents T cells, functional GABA-A channels are expressed but the subtypes vary. It is important to bear in mind the interspecies difference when selecting the appropriate animal models to study the physiological role and pharmacological properties of GABA-A channels in CD4(+ and CD8(+ T cells and when selecting drugs aimed at modulating the human T cells function.

  12. Cell-attached recordings of responses evoked by photorelease of GABA in the immature cortical neurons

    Directory of Open Access Journals (Sweden)

    Marat eMinlebaev


    Full Text Available We present a novel non-invasive technique to measure the polarity of GABAergic responses based on cell-attached recordings of currents activated by laser-uncaging of GABA. For these recordings, a patch pipette was filled with a solution containing RuBi-GABA, and GABA was released from this complex by a laser beam conducted to the tip of the patch pipette via an optic fiber. In cell-attached recordings from neocortical and hippocampal neurons in postnatal days P2-5 rat brain slices in vitro, we found that laser-uncaging of GABA activates integral cell-attached currents mediated by tens of GABA(A channels. The initial response was inwardly directed, indicating a depolarizing response to GABA. The direction of the initial response was dependent on the pipette potential and analysis of its slope-voltage relationships revealed a depolarizing driving force of +11 mV for the currents through GABA channels. Initial depolarizing responses to GABA uncaging were inverted to hyperpolarizing in the presence of the NKCC1 blocker bumetanide. Current-voltage relationships of the currents evoked by Rubi-GABA uncaging using voltage-ramps at the peak of responses not only revealed a bumetanide-sensitive depolarizing reversal potential of the GABA(A receptor mediated responses, but also showed a strong voltage-dependent hysteresis. Upon desensitization of the uncaged-GABA response, current-voltage relationships of the currents through single GABA(A channels revealed depolarizing responses with the driving force values similar to those obtained for the initial response. Thus, cell-attached recordings of the responses evoked by local intrapipette GABA uncaging are suitable to assess the polarity of the GABA(A-Rs mediated signals in small cell compartments.

  13. The astrocytic GABA(A)/benzodiazepine-like receptor: the Joker receptor for benzodiazepine-mimetic drugs? (United States)

    Hertz, Leif; Zhao, Zhong; Chen, Ye


    Long-term use of benzodiazepines as hypnotics, anxiolytics, anticonvulsants and muscle relaxing drugs is jeopardized by adverse effects on memory, addictive properties, and development of tolerance. Major efforts have gone into developing 'benzodiazepine-like' drugs that are more selective in their therapeutic effect, have additional uses and/or lack the adverse effects of benzodiazepines. The reviewed prototype patent exemplifies such efforts. Newer drugs are thought to act selectively on one of the two neuronal benzodiazepine receptors, on the astrocytic mitochondrial benzodiazepine receptor and/or on GABA(A)/benzodiazepine receptor complexes displaying specific subunits. It is overlooked that astrocytes also express benzodiazepine receptors that enhance depolarization-mediated entry of Ca(2+) by interacting with membrane-associated GABA(A)-like receptors, mediating depolarization because of a high Cl(-) concentration within astrocytes. The resulting increase in free cytosolic Ca(2+), which stimulates glycogenolysis, is inhibited not only by the 'peripheral-type" benzodiazepine antagonist PK11195 but also by the 'neuronal' antagonist flumazenil. Increasing awareness of the role(s) of astrocytic Ca(2+) homeostasis and energy metabolism for CNS function suggests that activation of this receptor might contribute to both therapeutic and adverse effects of benzodiazepine-like drugs. This receptor should be kept in mind when developing and testing new drugs; in turn these drugs may help elucidating its functional role.

  14. Role of GABA(B) receptors in learning and memory and neurological disorders. (United States)

    Heaney, Chelcie F; Kinney, Jefferson W


    Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Endogenous, Imperfectly Competitive Business Cycles

    DEFF Research Database (Denmark)

    Whitta-Jacobsen, Hans Jørgen

    We investigate how imperfect competition affects the occurrence and the properties of endogenous, rational expectations business cycles in an overlapping generations model with constant returns to scale in production. The model has explicit product and labor markets all characterized...

  16. Conformational basis for the Li(+)-induced leak current in the rat gamma-aminobutyric acid (GABA) transporter-1

    DEFF Research Database (Denmark)

    MacAulay, Nanna; Zeuthen, Thomas; Gether, Ulrik


    (+)-bound conformation of the protein displayed a lower passive water permeability than that of the Na(+)- and choline (Ch(+))-bound conformations and the leak current did not saturate with increasing amounts of Li(+) in the test solution. The mechanism that gives rise to the leak current did not support active water...... millimolar concentrations of Na(+) (the apparent affinity constant, K'(0.5) = 3 mM). In addition, it was found that the GABA transport current was sustained at correspondingly low Na(+) concentrations if Li(+) was present instead of choline. This is consistent with a model in which Li(+) can bind...

  17. Hippocampal GABA transporter distribution in patients with temporal lobe epilepsy and hippocampal sclerosis. (United States)

    Schijns, Olaf; Karaca, Ümit; Andrade, Pablo; de Nijs, Laurence; Küsters, Benno; Peeters, Andrea; Dings, Jim; Pannek, Heinz; Ebner, Alois; Rijkers, Kim; Hoogland, Govert


    To determine hippocampal expression of neuronal GABA-transporter (GAT-1) and glial GABA-transporter (GAT-3) in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). Hippocampal sections were immunohistochemically stained for GABA-transporter 1 and GABA-transporter-3, followed by quantification of the immunoreactivity in the hilus by optical density measurements. GABA-transporter 3 positive hilar cells were counted and GABA-transporter protein expression in sections that included all hippocampal subfields was quantified by Western blot. The hilar GABA-transporter 1 expression of patients with severe hippocampal sclerosis was about 7% lower compared to that in the mild hippocampal sclerosis/control group (psclerosis group than in the mild hippocampal sclerosis/control group (non-significant). Also, severe hippocampal sclerosis samples contained 34% less (non-significant) GABA-transporter 3 positive cells compared to that of controls. Protein expression as assessed by Western blot showed that GABA-transporter 1 was equally expressed in mild and severe hippocampal sclerosis samples, whereas GABA-transporter 3 was reduced by about 62% in severe hippocampal sclerosis samples (psclerosis. Implications for the use of GABAergic antiepileptic therapies in hippocampal sclerosis vs non-hippocampal sclerosis patients remain to be studied. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Molecular dynamics simulations of apo, holo, and inactivator bound GABA-at reveal the role of active site residues in PLP dependent enzymes. (United States)

    Gökcan, Hatice; Monard, Gerald; Sungur Konuklar, F Aylin


    The pyridoxal 5-phosphate (PLP) cofactor is a significant organic molecule in medicinal chemistry. It is often found covalently bound to lysine residues in proteins to form PLP dependent enzymes. An example of this family of PLP dependent enzymes is γ-aminobutyric acid aminotransferase (GABA-AT) which is responsible for the degradation of the neurotransmitter GABA. Its inhibition or inactivation can be used to prevent the reduction of GABA concentration in brain which is the source of several neurological disorders. As a test case for PLP dependent enzymes, we have performed molecular dynamics simulations of GABA-AT to reveal the roles of the protein residues and its cofactor. Three different states have been considered: the apoenzyme, the holoenzyme, and the inactive state obtained after the suicide inhibition by vigabatrin. Different protonation states have also been considered for PLP and two key active site residues: Asp298 and His190. Together, 24 independent molecular dynamics trajectories have been simulated for a cumulative total of 2.88 µs. Our results indicate that, unlike in aqueous solution, the PLP pyridine moiety is protonated in GABA-AT. This is a consequence of a pKa shift triggered by a strong charge-charge interaction with an ionic "diad" formed by Asp298 and His190 that would help the activation of the first half-reaction of the catalytic mechanism in GABA-AT: the conversion of PLP to free pyridoxamine phosphate (PMP). In addition, our MD simulations exhibit additional strong hydrogen bond networks between the protein and PLP: the phosphate group is held in place by the donation of at least three hydrogen bonds while the carbonyl oxygen of the pyridine ring interacts with Gln301; Phe181 forms a π-π stacking interaction with the pyridine ring and works as a gate keeper with the assistance of Val300. All these interactions are hypothesized to help maintain free PMP in place inside the protein active site to facilitate the second half

  19. Stoichiometry of δ subunit containing GABA(A) receptors. (United States)

    Patel, B; Mortensen, M; Smart, T G


    Although the stoichiometry of the major synaptic αβγ subunit-containing GABAA receptors has consensus support for 2α:2β:1γ, a clear view of the stoichiometry of extrasynaptic receptors containing δ subunits has remained elusive. Here we examine the subunit stoichiometry of recombinant α4β3δ receptors using a reporter mutation and a functional electrophysiological approach. Using site-directed mutagenesis, we inserted a highly characterized 9' serine to leucine mutation into the second transmembrane (M2) region of α4, β3 and δ subunits that increases receptor sensitivity to GABA. Whole-cell, GABA-activated currents were recorded from HEK-293 cells co-expressing different combinations of wild-type (WT) and/or mutant α4(L297S), β3(L284S) and δ(L288S) subunits. Recombinant receptors containing one or more mutant subunits showed increased GABA sensitivity relative to WT receptors by approximately fourfold, independent of the subunit class (α, β or δ) carrying the mutation. GABA dose-response curves of cells co-expressing WT subunits with their respective L9'S mutants exhibited multiple components, with the number of discernible components enabling a subunit stoichiometry of 2α, 2β and 1δ to be deduced for α4β3δ receptors. Varying the cDNA transfection ratio by 10-fold had no significant effect on the number of incorporated δ subunits. Subunit stoichiometry is an important determinant of GABAA receptor function and pharmacology, and δ subunit-containing receptors are important mediators of tonic inhibition in several brain regions. Here we demonstrate a preferred subunit stoichiometry for α4β3δ receptors of 2α, 2β and 1δ. © 2013 The British Pharmacological Society.

  20. GABA(A) receptor modulation during adolescence alters adult ethanol intake and preference in rats. (United States)

    Hulin, Mary W; Amato, Russell J; Winsauer, Peter J


    To address the hypothesis that GABA(A) receptor modulation during adolescence may alter the abuse liability of ethanol during adulthood, the effects of adolescent administration of both a positive and negative GABA(A) receptor modulator on adult alcohol intake and preference were assessed. Three groups of adolescent male rats received 12 injections of lorazepam (3.2 mg/kg), dehydroepiandrosterone (DHEA, 56 mg/kg), or vehicle on alternate days starting on postnatal day (PD) 35. After this time, the doses were increased to 5.6 and 100 mg/kg, respectively, for 3 more injections on alternate days. Subjects had access to 25 to 30 g of food daily, during the period of the first 6 injections, and 18 to 20 g thereafter. Food intake of each group was measured 60 minutes after food presentation, which occurred immediately after drug administration on injection days or at the same time of day on noninjection days. When subjects reached adulthood (PD 88), ethanol preference was determined on 2 separate occasions, an initial 3-day period and a 12-day period, in which increasing concentrations of ethanol were presented. During each preference test, intake of water, saccharin, and an ethanol/saccharin solution was measured after each 23-hour access period. During adolescence, lorazepam increased 60-minute food intake, and this effect was enhanced under the more restrictive feeding schedule. DHEA had the opposite effect on injection days, decreasing food intake compared with noninjection days. In adulthood, the lorazepam-treated group preferred the 2 lowest concentrations of ethanol/saccharin more than saccharin alone compared with vehicle-treated subjects, which showed no preference for any concentration of ethanol/saccharin over saccharin. DHEA-treated subjects showed no preference among the 3 solutions. These data demonstrate that GABA(A) receptor modulation during adolescence can alter intake and preference for ethanol in adulthood and highlights the importance of drug history

  1. Circadian control of the daily plasma glucose rhythm: an interplay of GABA and glutamate.

    Directory of Open Access Journals (Sweden)

    Andries Kalsbeek

    Full Text Available The mammalian biological clock, located in the hypothalamic suprachiasmatic nuclei (SCN, imposes its temporal structure on the organism via neural and endocrine outputs. To further investigate SCN control of the autonomic nervous system we focused in the present study on the daily rhythm in plasma glucose concentrations. The hypothalamic paraventricular nucleus (PVN is an important target area of biological clock output and harbors the pre-autonomic neurons that control peripheral sympathetic and parasympathetic activity. Using local administration of GABA and glutamate receptor (antagonists in the PVN at different times of the light/dark-cycle we investigated whether daily changes in the activity of autonomic nervous system contribute to the control of plasma glucose and plasma insulin concentrations. Activation of neuronal activity in the PVN of non-feeding animals, either by administering a glutamatergic agonist or a GABAergic antagonist, induced hyperglycemia. The effect of the GABA-antagonist was time dependent, causing increased plasma glucose concentrations only when administered during the light period. The absence of a hyperglycemic effect of the GABA-antagonist in SCN-ablated animals provided further evidence for a daily change in GABAergic input from the SCN to the PVN. On the other hand, feeding-induced plasma glucose and insulin responses were suppressed by inhibition of PVN neuronal activity only during the dark period. These results indicate that the pre-autonomic neurons in the PVN are controlled by an interplay of inhibitory and excitatory inputs. Liver-dedicated sympathetic pre-autonomic neurons (responsible for hepatic glucose production and pancreas-dedicated pre-autonomic parasympathetic neurons (responsible for insulin release are controlled by inhibitory GABAergic contacts that are mainly active during the light period. Both sympathetic and parasympathetic pre-autonomic PVN neurons also receive excitatory inputs, either

  2. Flavonoid nutraceuticals and ionotropic receptors for the inhibitory neurotransmitter GABA. (United States)

    Johnston, Graham A R


    Flavonoids that are found in nutraceuticals have many and varied effects on the activation of ionotropic receptors for GABA, the major inhibitory neurotransmitter in our brains. They can act as positive or negative modulators enhancing or reducing the effect of GABA. They can act as allosteric agonists. They can act to modulate the action of other modulators. There is considerable evidence that these flavonoids are able to enter the brain to influence brain function. They may have a range of effects including relief of anxiety, improvement in cognition, acting as neuroprotectants and as sedatives. All of these effects are sought after in nutraceuticals. A number of studies have likened flavonoids to the widely prescribed benzodiazepines as 'a new family of benzodiazepine receptor ligands'. They are much more than that with many flavonoid actions on ionotropic GABA receptors being insensitive to the classic benzodiazepine antagonist flumazenil and thus independent of the classic benzodiazepine actions. It is time to consider flavonoids in their own right as important modulators of these vital receptors in brain function. Flavonoids are rarely consumed as a single flavonoid except as dietary supplements. The effects of mixtures of flavonoids and other modulators on GABAA receptors need to be more thoroughly investigated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. The GABA transaminase, ABAT, is essential for mitochondrial nucleoside metabolism (United States)

    Besse, Arnaud; Wu, Ping; Bruni, Francesco; Donti, Taraka; Graham, Brett H.; Craigen, William J.; McFarland, Robert; Moretti, Paolo; Lalani, Seema; Scott, Kenneth L.; Taylor, Robert W.; Bonnen, Penelope E.


    Summary ABAT is a key enzyme responsible for catabolism of principal inhibitory neurotransmitter gamma-aminobutyric acid (GABA). We report an essential role for ABAT in a seemingly unrelated pathway, mitochondrial nucleoside salvage, and demonstrate that mutations in this enzyme cause an autosomal recessive neurometabolic disorder and mtDNA depletion syndrome (MDS). We describe a family with encephalomyopathic MDS caused by a homozygous missense mutation in ABAT that results in elevated GABA in subjects’ brains as well as decreased mtDNA levels in subjects’ fibroblasts. Nucleoside rescue and co-IP experiments pinpoint that ABAT functions in the mitochondrial nucleoside salvage pathway to facilitate conversion of dNDPs to dNTPs. Pharmacological inhibition of ABAT through the irreversible inhibitor Vigabatrin caused depletion of mtDNA in photoreceptor cells that was prevented through addition of dNTPs in cell culture media. This work reveals ABAT as a connection between GABA metabolism and nucleoside metabolism and defines a neurometabolic disorder that includes MDS. PMID:25738457

  4. Human Occipital and Parietal GABA Selectively Influence Visual Perception of Orientation and Size. (United States)

    Song, Chen; Sandberg, Kristian; Andersen, Lau Møller; Blicher, Jakob Udby; Rees, Geraint


    GABA is the primary inhibitory neurotransmitter in human brain. The level of GABA varies substantially across individuals, and this variability is associated with interindividual differences in visual perception. However, it remains unclear whether the association between GABA level and visual perception reflects a general influence of visual inhibition or whether the GABA levels of different cortical regions selectively influence perception of different visual features. To address this, we studied how the GABA levels of parietal and occipital cortices related to interindividual differences in size, orientation, and brightness perception. We used visual contextual illusion as a perceptual assay since the illusion dissociates perceptual content from stimulus content and the magnitude of the illusion reflects the effect of visual inhibition. Across individuals, we observed selective correlations between the level of GABA and the magnitude of contextual illusion. Specifically, parietal GABA level correlated with size illusion magnitude but not with orientation or brightness illusion magnitude; in contrast, occipital GABA level correlated with orientation illusion magnitude but not with size or brightness illusion magnitude. Our findings reveal a region- and feature-dependent influence of GABA level on human visual perception. Parietal and occipital cortices contain, respectively, topographic maps of size and orientation preference in which neural responses to stimulus sizes and stimulus orientations are modulated by intraregional lateral connections. We propose that these lateral connections may underlie the selective influence of GABA on visual perception.SIGNIFICANCE STATEMENT GABA, the primary inhibitory neurotransmitter in human visual system, varies substantially across individuals. This interindividual variability in GABA level is linked to interindividual differences in many aspects of visual perception. However, the widespread influence of GABA raises the


    Directory of Open Access Journals (Sweden)

    I. V. Aleksandrova


    Full Text Available RELEVANCE. Sepsis is always accompanied by endogenous intoxication (EI. It is very important to study EI in the patients with severe sepsis and septic shock.MATERIAL AND METHODS. Twenty seven patients with severe sepsis and thirteen with septic shock in the postoperative period were enrolled into the study. EI was assessed using the measurements of total and effective albumin concentrations (EAC, middle-molecular-weight proteins (MMWP and EI index (Kei=MMWP/ EACx1000.RESULTS. The use of the EI index in patients with severe sepsis and septic shock leads to improvement of diagnostic and therapy monitoring.

  6. Cloning and characterization of a functional human ¿-aminobutyric acid (GABA) transporter, human GAT-2

    DEFF Research Database (Denmark)

    Christiansen, Bolette; Meinild, Anne-Kristine; Jensen, Anders A.


    Plasma membrane gamma-aminobutyric acid (GABA) transporters act to terminate GABA neurotransmission in the mammalian brain. Intriguingly four distinct GABA transporters have been cloned from rat and mouse, whereas only three functional homologs of these transporters have been cloned from human....... The aim of this study therefore was to search for this fourth missing human transporter. Using a bioinformatics approach, we successfully identified and cloned the full-length cDNA of a so far uncharacterized human GABA transporter (GAT). The predicted protein displays high sequence similarity to rat GAT...... in human. Furthermore the availability of human GAT-2 enables the use of all human clones of the GABA transporters in drug development programs and functional characterization of novel inhibitors of GABA transport....

  7. Allosteric modulation by benzodiazepines of GABA-gated chloride channels of an identified insect motor neurone. (United States)

    Buckingham, Steven D; Higashino, Yoshiaki; Sattelle, David B


    The actions of benzodiazepines were studied on the responses to GABA of the fast coxal depressor (D(f)) motor neurone of the cockroach, Periplaneta americana. Ro5-4864, diazepam and clonazepam were investigated. Responses to GABA receptors were enhanced by both Ro5-4864 and diazepam, whereas clonazepam, a potent-positive allosteric modulator of human GABA(A) receptors, was ineffective on the native insect GABA receptors of the D(f) motor neurone. Thus, clear pharmacological differences exist between insect and mammalian native GABA-gated chloride channels with respect to the actions of benzodiazepines. The results enhance our understanding of invertebrate GABA-gated chloride channels which have recently proved important in (a) comparative studies aimed at identifying human allosteric drug-binding sites and (b) understanding the actions of compounds used to control ectoparasites and insect crop pests.

  8. Efficient increase of ?-aminobutyric acid (GABA) content in tomato fruits by targeted mutagenesis


    Nonaka, Satoko; Arai, Chikako; Takayama, Mariko; Matsukura, Chiaki; Ezura, Hiroshi


    γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid that has hypotensive effects. Tomato (Solanum lycopersicum L.) is among the most widely cultivated and consumed vegetables in the world and contains higher levels of GABA than other major crops. Increasing these levels can further enhance the blood pressure-lowering function of tomato fruit. Glutamate decarboxylase (GAD) is a key enzyme in GABA biosynthesis; it has a C-terminal autoinhibitory domain that regulates enzymatic function...

  9. Selected Gamma Aminobutyric Acid (GABA) Esters may Provide Analgesia for Some Central Pain Conditions


    Goldberg, Joel S.


    Central pain is an enigmatic, intractable condition, related to destruction of thalamic areas, resulting in likely loss of inhibitory synaptic transmission mediated by GABA. It is proposed that treatment of central pain, a localized process, may be treated by GABA supplementation, like Parkinson’s disease and depression. At physiologic pH, GABA exists as a zwitterion that is poorly permeable to the blood brain barrier (BBB). Because the pH of the cerebral spinal fluid (CSF) is acidic relative...

  10. Pipecolic acid enhancement of GABA response in single neurons of rat brain. (United States)

    Takahama, K; Hashimoto, T; Wang, M W; Akaike, N; Hitoshi, T; Okano, Y; Kasé, Y; Miyata, T


    Using unit recording and microelectrophoresis, influence of pipecolic acid (PA), a major metabolite of lysine in the brain, on GABA and glycine responses was studied in the cerebral cortical and hippocampal pyramidal neurons of rats. With small currents, PA had no effect on the single neuron activities but enhanced GABA response without affecting glycine response. The finding provides a new evidence that PA may have a connection with central GABA system.

  11. GABA_A receptor function is regulated by lipid bilayer elasticity

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Werge, Thomas; Berthelsen, Camilla


    Docosahexaenoic acid ( DHA) and other polyunsaturated fatty acids ( PUFAs) promote GABA(A) receptor [ (3)H]-muscimol binding, and DHA increases the rate of GABAA receptor desensitization. Triton X-100, a structurally unrelated amphiphile, similarly promotes [ (3)H]-muscimol binding. The mechanism......( s) underlying these effects are poorly understood. DHA and Triton X-100, at concentrations that affect GABAA receptor function, increase the elasticity of lipid bilayers measured as decreased bilayer stiffness using gramicidin channels as molecular force transducers. We have previously shown......-beta-glucoside, capsaicin, and DHA) on GABAA receptor function in mammalian cells. All the compounds promoted GABAA receptor [ (3)H]-muscimol binding by increasing the binding capacity of high- affinity binding without affecting the associated equilibrium binding constant. A semiquantitative analysis found a similar...

  12. GABA affects novel object recognition memory and working memory in rats. (United States)

    Thanapreedawat, Panicha; Kobayashi, Hiroki; Inui, Naoto; Sakamoto, Kazuhiro; Kim, Mujo; Yoto, Ai; Yokogoshi, Hidehiko


    γ-Aminobutyric acid (GABA) is an amino acid found in unpolished rice, chocolate, tea, and other foods. It is an important inhibitory neurotransmitter. However, the influence of GABA on object recognition and working memory is still unknown. In this study, the effects of GABA on novel object recognition (NOR) memory and working memory were examined. The proper retention interval and delay time were also investigated for the NOR test and T-maze test, respectively. Male 3-wk-old Wistar rats were allowed free access to food and water containing 0.5% GABA or 1% GABA for a month. After that, the rats performed the NOR test at a 48 h retention interval and T-maze test at a 900 s delay time to estimate the effects of GABA on learning behavior. The results showed that the object information in the NOR test was stored as long-term memory and the recognition index (RI) was significantly increased after GABA administration. The accuracy rate also significantly increased after GABA administration. These indicate that GABA may be involved in long-term object recognition memory and working memory.

  13. Differential sensitivity of two insect GABA-gated chloride channels to dieldrin, fipronil and picrotoxinin. (United States)

    Le Corronc, Hervé; Alix, Philippe; Hue, Bernard


    In the central nervous system of both vertebrates and invertebrates inhibitory neurotransmission is mainly achieved through activation of gamma-aminobutyric acid (GABA) receptors. Extensive studies have established the structural and pharmacological properties of vertebrate GABA receptors. Although the vast majority of insect GABA-sensitive responses share some properties with vertebrate GABAA receptors, peculiar pharmacological properties of these receptors led us to think that several GABA-gated chloride channels are present in insects. We describe here the pharmacological properties of two GABA receptor subtypes coupled to a chloride channel on dorsal unpaired median (DUM) neurones of the adult male cockroach. Long applications of GABA induce a large biphasic hyperpolarization, consisting of an initial transient hyperpolarization followed by a slow phase of hyperpolarization that is not quickly desensitized. With GABA, the transient hyperpolarization is sensitive to picrotoxinin, fipronil and dieldrin whereas the slow response is insensitive to these insecticides.When GABA is replaced by muscimol and cis-4-aminocrotonic acid (CACA) a biphasic hyperpolarization consisting of an initial transient hyperpolarization followed by a sustained phase is evoked which is blocked by picrotoxinin and fipronil. Exposure to dieldrin decreases only the early phase of the muscimol and CACA-induced biphasic response, suggesting that two GABA-gated chloride channel receptor subtypes are present in DUM neurones. This study describes, for the first time, a dieldrin resistant component different to the dieldrin- and picrotoxinin-resistant receptor found in several insect species.

  14. Compartmentalization of GABA synthesis by GAD67 differs between pancreatic beta cells and neurons

    DEFF Research Database (Denmark)

    Kanaani, Jamil; Cianciaruso, Chiara; Phelps, Edward A


    The inhibitory neurotransmitter GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD) in neurons and in pancreatic β-cells in islets of Langerhans where it functions as a paracrine and autocrine signaling molecule regulating the function of islet endocrine cells. The localization...... of the two non-allelic isoforms GAD65 and GAD67 to vesicular membranes is important for rapid delivery and accumulation of GABA for regulated secretion. While the membrane anchoring and trafficking of GAD65 are mediated by intrinsic hydrophobic modifications, GAD67 remains hydrophilic, and yet is targeted...... accumulation of newly synthesized GABA for regulated secretion and fine tuning of GABA-signaling in islets of Langerhans....

  15. Prospective frequency correction for macromolecule-suppressed GABA editing at 3T

    DEFF Research Database (Denmark)

    Edden, Richard A E; Oeltzschner, Georg; Harris, Ashley D


    PURPOSE: To investigate the effects of B0 field offsets and drift on macromolecule (MM)-suppressed GABA-editing experiments, and to implement and test a prospective correction scheme. "Symmetric" editing schemes are proposed to suppress unwanted coedited MM signals in GABA editing. MATERIALS...... were performed to quantify the effects of field offsets on the total GABA+MM signal (designated GABA+). A prospective frequency correction method based on interleaved water referencing (IWR) acquisitions was implemented and its experimental performance evaluated during positive and negative drift...

  16. The plant GABA signaling downregulates horizontal transfer of the Agrobacterium tumefaciens virulence plasmid. (United States)

    Lang, Julien; Gonzalez-Mula, Almudena; Taconnat, Ludivine; Clement, Gilles; Faure, Denis


    In the tumor-inducing (Ti) Agrobacterium tumefaciens, quorum sensing activates the horizontal transfer of the virulent Ti plasmid. In pure culture, this process can be impaired by the A. tumefaciens BlcC lactonase, whose expression is induced by gamma-aminobutyrate (GABA). It was therefore hypothesized that host GABA content might modulate quorum sensing and virulence gene dissemination during A. tumefaciens infection. We examined GABA metabolism and transport in Arabidopsis thaliana tumors combining transcriptomic, metabolomic and histological approaches. In addition, using genetically modified plants and bacteria, we evaluated the impact of plant host GABA content on Ti plasmid dissemination. The results showed that GABA and free proline, which acts as an antagonist of GABA uptake in A. tumefaciens, accumulated in wild-type tumors relative to uninfected plant tissues. Moreover, comparisons of tumors induced on Col-0 and her1 plants showed that the increase in the plant GABA : proline ratio was associated with both the upregulated expression of the blcC gene and the decreased dissemination of Ti plasmid in tumor-colonizing A. tumefaciens populations. This work demonstrates experimentally that the variation in the GABA content in plant tumors can interfere with the dissemination of A. tumefaciens Ti plasmids, and therefore highlights plant GABA content as an important trait in the struggle against pathogenic bacteria. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  17. Neurotransmitters as food supplements: the effects of GABA on brain and behavior. (United States)

    Boonstra, Evert; de Kleijn, Roy; Colzato, Lorenza S; Alkemade, Anneke; Forstmann, Birte U; Nieuwenhuis, Sander


    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood-brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA.

  18. Neurobiological mechanisms involved in nicotine dependence and reward: participation of the endogenous opioid system (United States)

    Berrendero, Fernando; Robledo, Patricia; Trigo, José Manuel; Martín-García, Elena; Maldonado, Rafael


    Nicotine is the primary component of tobacco that maintains the smoking habit and develops addiction. The adaptive changes of nicotinic acetylcholine receptors produced by repeated exposure to nicotine play a crucial role in the establishment of dependence. However, other neurochemical systems also participate in the addictive effects of nicotine including glutamate, cannabinoids, GABA and opioids. This review will cover the involvement of these neurotransmitters in nicotine addictive properties, with a special emphasis on the endogenous opioid system. Thus, endogenous enkephalins and beta-endorphins acting on mu-opioid receptors are involved in nicotine rewarding effects, whereas opioid peptides derived from prodynorphin participate in nicotine aversive responses. An upregulation of mu-opioid receptors has been reported after chronic nicotine treatment that could counteract the development of nicotine tolerance, whereas the downregulation induced on kappa-opioid receptors seems to facilitate nicotine tolerance. Endogenous enkephalins acting on mu-opioid receptors also play a role in the development of physical dependence to nicotine. In agreement with these actions of the endogenous opioid system, the opioid antagonist naltrexone has shown to be effective for smoking cessation in certain subpopulations of smokers. PMID:20170672

  19. The beta-lactam antibiotics, penicillin-G and cefoselis have different mechanisms and sites of action at GABA(A) receptors

    National Research Council Canada - National Science Library

    Sugimoto, Masahiro; Fukami, Sakae; Kayakiri, Hiroshi; Yamazaki, Shunji; Matsuoka, Nobuya; Uchida, Ichiro; Mashimo, Takashi


    The action of the beta-lactam antibiotics, penicillin-G (PCG) and cefoselis (CFSL) on GABA(A) receptors (GABA(A)-R) was investigated using the two-electrode voltage clamp technique and Xenopus oocyte expressed murine GABA...

  20. A note on endogenous transfers

    NARCIS (Netherlands)

    S. Brakman (Steven); J.G.M. van Marrewijk (Charles)


    textabstractIn a competitive and Walrasian stable world with two goods transfer paradoxes are very robust to endogenization (relating the size of the transfer to either the donor's or the recipient's GNP). Donor enrichment and/or recipient impoverishment occur in very general formulations of

  1. Monopoly Insurance and Endogenous Information

    DEFF Research Database (Denmark)

    Lagerlöf, Johan N. M.; Schottmüller, Christoph


    We study a monopoly insurance model with endogenous information acquisi- tion. Through a continuous effort choice, consumers can determine the precision of a privately observed signal that is informative about their accident risk. The equilibrium effort is, depending on parameter values, either...

  2. Glutamate and GABA in vestibulo-sympathetic pathway neurons

    Directory of Open Access Journals (Sweden)

    Gay R Holstein


    Full Text Available The vestibulo-sympathetic reflex actively modulates blood pressure during changes in posture. This reflex allows humans to stand up and quadrupeds to rear or climb without a precipitous decline in cerebral perfusion. The vestibulo-sympathetic reflex pathway conveys signals from the vestibular end organs to the caudal vestibular nuclei. These cells, in turn, project to pre-sympathetic neurons in the rostral and caudal ventrolateral medulla (RVLM and CVLM, respectively. The present study assessed glutamate- and GABA-related immunofluorescence associated with central vestibular neurons of the vestibulo-sympathetic reflex pathway in rats. Retrograde FluoroGold tract tracing was used to label vestibular neurons with projections to RVLM or CVLM, and sinusoidal galvanic vestibular stimulation was employed to activate these pathways. Central vestibular neurons of the vestibulo-sympathetic reflex were identified by co-localization of FluoroGold and cFos protein, which accumulates in some vestibular neurons following galvanic stimulation. Triple-label immunofluorescence was used to co-localize glutamate- or GABA- labeling in the identified vestibulo-sympathetic reflex pathway neurons. Most activated projection neurons displayed intense glutamate immunofluorescence, suggestive of glutamatergic neurotransmission. To support this, anterograde tracer was injected into the caudal vestibular nuclei. Vestibular axons and terminals in RVLM and CVLM co-localized the anterograde tracer and vesicular glutamate transporter-2 signals. Other retrogradely-labeled cFos-positive neurons displayed intense GABA immunofluorescence. Vestibulo-sympathetic reflex pathway neurons of both phenotypes were present in the caudal medial and spinal vestibular nuclei, and projected to both RVLM and CVLM. As a group, however, triple-labeled vestibular cells with intense glutamate immunofluorescence were located more rostrally in the vestibular nuclei than the GABAergic neurons. Only the

  3. Validation of an extended method for the detection of the misuse of endogenous steroids in sports, including new hydroxylated metabolites. (United States)

    Van Renterghem, P; Van Eenoo, P; Van Thuyne, W; Geyer, H; Schänzer, W; Delbeke, F T


    Endogenous steroids are amongst the most misused doping agents in sports. Their presence poses a major challenge for doping control laboratories. Current threshold levels do not allow for the detection of all endogenous steroid misuse due to great interindividual variations in urinary steroid concentrations. A method has been developed and validated to screen for traditionally monitored endogenous steroids in doping control as well as specific hydroxylated/oxygenated metabolites in order to enhance the detection capabilities for the misuse of endogenous steroids.

  4. Endogenous opioid peptides in uterine fluid. (United States)

    Petraglia, F; Facchinetti, F; M'Futa, K; Ruspa, M; Bonavera, J J; Gandolfi, F; Genazzani, A R


    The present study demonstrates the presence of the endogenous opioid peptides beta-endorphin (beta-EP) and methionine-enkephalin (MET-ENK), in the uterine fluid of fertile women and normally cycling and superovulated cows. The two peptides are undetectable in the uterine fluid of untreated postmenopausal women, whereas they are present following estrogen-progesterone treatment. Immunoreactive (IR) MET-ENK concentrations were higher in the secretory than in the proliferative phase of the menstrual cycle. IR beta-EP and IR MET-ENK are present also in the follicular, oviductal, and uterine fluid of cows, and in the uterine fluid, concentrations of IR MET-ENK are higher in the superovulated than in the control animals. Because opioids play important roles on endocrine and immune functions, the present data support the potential physiologic role of endometrial secretions.

  5. Depolarization by K*O+ and glutamate activates different neurotransmitter release mechanisms in gabaergic neurons: vesicular versus non-vesicular release of gaba

    DEFF Research Database (Denmark)

    Belhage, Bo; Hansen, G.H.; Schousboe, Arne


    Neurotransmitter release, gaba release, membrane transporter, vesicles, intracellular CA*OH, neuron cultures......Neurotransmitter release, gaba release, membrane transporter, vesicles, intracellular CA*OH, neuron cultures...

  6. Positive modulation of delta-subunit containing GABAA receptors in mouse neurons

    DEFF Research Database (Denmark)

    Vardya, Irina; Hoestgaard-Jensen, Kirsten; Nieto-Gonzalez, Jose Luis


    -free environment using Ca²⁺ imaging in cultured neurons, AA29504 showed GABA(A) receptor agonism in the absence of agonist. Finally, AA29504 exerted dose-dependent stress-reducing and anxiolytic effects in mice in vivo. We propose that AA29504 potentiates δ-containing GABA(A) receptors to enhance tonic inhibition...

  7. GABA receptors and benzodiazepine binding sites modulate hippocampal acetylcholine release in vivo

    NARCIS (Netherlands)

    Moor, E; de Boer, P; Westerink, B.H.C.


    In the present study, the regulation of acetylcholine release from the ventral hippocampus by gamma-aminobutyric acid (GABA) was investigated in vivo. GABA receptor agonists and antagonists were administered locally in the medial septum and the adjacent vertical limb of the diagonal band of Broca,

  8. A Unified Model of the GABA(A) Receptor Comprising Agonist and Benzodiazepine Binding Sites

    DEFF Research Database (Denmark)

    Kongsbak, Kristine Grønning; Bergmann, Rikke; Sørensen, Pernille Louise


    We present a full-length a1b2c2 GABA receptor model optimized for agonists and benzodiazepine (BZD) allosteric modulators. We propose binding hypotheses for the agonists GABA, muscimol and THIP and for the allosteric modulator diazepam (DZP). The receptor model is primarily based on the glutamate...

  9. Study on flavour volatiles of γ-aminobutyric acid (GABA) green tea ...

    African Journals Online (AJOL)

    The volatile components of γ-aminobutyric acid (GABA) tea produced by two different kinds of technological process separately namely: vacuum and water immersion were studied. It was shown by the sensory evaluation that the color of the soup and the extracted leaves of GABA tea were similar to that of the oolong tea, ...


    NARCIS (Netherlands)


    Brain microdialysis was used to characterize extracellular gamma-aminobutyric acid (GABA) in the substantia nigra reticulata (SNR) of freely moving rats. The extracellular GABA in the SNR was characterized using acutely implanted probes (4-8 h after surgery; day 1) and chronically implanted probes

  11. Electrically evoked GABA release in rat hippocampus CA1 region and its changes during kindling epileptogenesis.

    NARCIS (Netherlands)

    Ghijsen, W.E.J.M.; Zuiderwijk, M.; Lopes da Silva, F.H.


    Previous findings on changes in K(+)-induced GABA release from hippocampal slices during kindling epileptogenesis were reinvestigated using physiological electrical stimulation. For that purpose, a procedure was developed enabling neurochemical monitoring of GABA release locally in the CA1 region of

  12. Circadian modulation of GABA function in the rat suprachiasmatic nucleus: excitatory effects during the night phase.

    NARCIS (Netherlands)

    De Jeu, M.T.G.; Pennartz, C.M.A.


    Gramicidin-perforated patch-clamp recordings were made from slices of the suprachiasmatic nucleus (SCN) of adult rats to characterize the role of gamma-amino butyric acid (GABA) in the circadian timing system. During the day, activation of GABA(A) receptors hyperpolarized the membrane of SCN

  13. Temperature dependence and GABA modulation of (TH)triazolam binding in the rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Earle, M.E.; Concas, A.; Wamsley, J.K.; Yamamura, H.I.


    The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of (TH)TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0C; K/sub d/ = 1.96 +/- 0.85 nM at 37C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0C and 1160 +/- 383 fmoles/mg protein at 37C). Saturation studies of (TH)TZ binding in the presence or absence of GABA (100 M) showed a GABA-shift. At 0C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables.

  14. γ-aminobutyric acid (GABA) oral rinse reduces capsaicin-induced burning mouth pain sensation

    DEFF Research Database (Denmark)

    Zhang, Yang; Wang, Kelun; Arendt-Nielsen, Lars


    BACKGROUND: In burning mouth patients, analgesia after oral administration of clonazepam may result from modulation of peripheral γ-aminobutyric acid (GABA) receptors. METHODS: The effect of oral administration of test solutions (water, 0.5 mol/L or 0.05 mol/L GABA, 1% lidocaine) was investigated...

  15. Restoration of GABA production machinery in Lactobacillus brevis by accessible carbohydrates, anaerobiosis and early acidification. (United States)

    Wu, Qinglong; Shah, Nagendra P


    Lactobacillus brevis is an efficient cell factory for producing bioactive γ-aminobutyric acid (GABA) by its gad operon-encoded glutamic acid decarboxylase (GAD) system. However, little mechanistic insights have been reported on the effects of carbohydrate, oxygen and early acidification on GABA production machinery in Lb. brevis. In the present study, GABA production from Lb. brevis was enhanced by accessible carbohydrates. Fast growth of this organism was stimulated by maltose and xylose. However, its GABA production was highly suppressed by oxygen exposure, but was fully restored by anaerobiosis that up-regulated the expression of gad operon in Lb. brevis cells. Although the level of cytosolic acidity was suitable for the functioning of GadA and GadB, early acidification of the medium (ipH 5 and ipH 4) restored GABA synthesis strictly in aerated cells of Lb. brevis because the expression of gad operon was not up-regulated in them. We conclude that GABA production machinery in Lb. brevis could be restored by accessible carbohydrates, anaerobiosis and early acidification. This will be of interest for controlling fermentation for synthesis of GABA and manufacturing GABA-rich fermented vegetables. Copyright © 2017. Published by Elsevier Ltd.

  16. Molecular basis of the alternative recruitment of GABA(A) versus glycine receptors through gephyrin

    DEFF Research Database (Denmark)

    Maric, Hans-Michael; Kasaragod, Vikram Babu; Hausrat, Torben Johann


    γ-Aminobutyric acid type A and glycine receptors (GABA(A)Rs, GlyRs) are the major inhibitory neurotransmitter receptors and contribute to many synaptic functions, dysfunctions and human diseases. GABA(A)Rs are important drug targets regulated by direct interactions with the scaffolding protein ge...

  17. Neurotransmitters as food supplements: the effects of GABA on brain and behavior

    Directory of Open Access Journals (Sweden)

    Evert eBoonstra


    Full Text Available The food supplement version of gamma-aminobutyric acid (GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood brain barrier (BBB, but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA.

  18. The GABA(A) receptor is an FMRP target with therapeutic potential in fragile X syndrome

    NARCIS (Netherlands)

    Braat, Sien; D'Hulst, Charlotte; Heulens, Inge; De Rubeis, Silvia; Mientjes, Edwin; Nelson, David L.; Willemsen, Rob; Bagni, Claudia; Van Dam, Debby; De Deyn, Peter P.; Kooy, R. Frank


    Previous research indicates that the GABA(A)ergic system is involved in the pathophysiology of the fragile X syndrome, a frequent form of inherited intellectual disability and associated with autism spectrum disorder. However, the molecular mechanism underlying GABA(A)ergic deficits has remained

  19. Identification of the first highly selective inhibitor of human GABA transporter GAT3

    DEFF Research Database (Denmark)

    Damgaard, Maria; Al-Khawaja, Anas; Vogensen, Stine B.


    Screening a library of small-molecule compounds using a cell line expressing human GABA transporter 3 (hGAT3) in a [(3)H]GABA uptake assay identified isatin derivatives as a new class of hGAT3 inhibitors. A subsequent structure-activity relationship (SAR) study led to the identification of hGAT3...

  20. Neurotransmitters as food supplements: the effects of GABA on brain and behavior

    NARCIS (Netherlands)

    Boonstra, E.; Kleijn, R.; Colzato, L.S.; Alkemade, A.; Forstmann, B.U.; Nieuwenhuis, S.


    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer

  1. Distribution of glycine/GABA neurons in the ventromedial medulla with descending spinal projections and evidence for an ascending glycine/GABA projection. (United States)

    Hossaini, Mehdi; Goos, Jacqueline A C; Kohli, Somesh K; Holstege, Jan C


    The ventromedial medulla (VM), subdivided in a rostral (RVM) and a caudal (CVM) part, has a powerful influence on the spinal cord. In this study, we have identified the distribution of glycine and GABA containing neurons in the VM with projections to the cervical spinal cord, the lumbar dorsal horn, and the lumbar ventral horn. For this purpose, we have combined retrograde tracing using fluorescent microspheres with fluorescent in situ hybridization (FISH) for glycine transporter 2 (GlyT2) and GAD67 mRNAs to identify glycinergic and/or GABAergic (Gly/GABA) neurons. Since the results obtained with FISH for GlyT2, GAD67, or GlyT2 + GAD67 mRNAs were not significantly different, we concluded that glycine and GABA coexisted in the various projection neurons. After injections in the cervical cord, we found that 29% ± 1 (SEM) of the retrogradely labeled neurons in the VM were Gly/GABA (RVM: 43%; CVM: 21%). After lumbar dorsal horn injections 31% ± 3 of the VM neurons were Gly/GABA (RVM: 45%; CVM: 12%), and after lumbar ventral horn injections 25% ± 2 were Gly/GABA (RVM: 35%; CVM: 17%). In addition, we have identified a novel ascending Gly/GABA pathway originating from neurons in the area around the central canal (CC) throughout the spinal cord and projecting to the RVM, emphasizing the interaction between the ventromedial medulla and the spinal cord. The present study has now firmly established that GABA and glycine are present in many VM neurons that project to the spinal cord. These neurons strongly influence spinal processing, most notably the inhibition of nociceptive transmission.

  2. Distribution of glycine/GABA neurons in the ventromedial medulla with descending spinal projections and evidence for an ascending glycine/GABA projection.

    Directory of Open Access Journals (Sweden)

    Mehdi Hossaini

    Full Text Available The ventromedial medulla (VM, subdivided in a rostral (RVM and a caudal (CVM part, has a powerful influence on the spinal cord. In this study, we have identified the distribution of glycine and GABA containing neurons in the VM with projections to the cervical spinal cord, the lumbar dorsal horn, and the lumbar ventral horn. For this purpose, we have combined retrograde tracing using fluorescent microspheres with fluorescent in situ hybridization (FISH for glycine transporter 2 (GlyT2 and GAD67 mRNAs to identify glycinergic and/or GABAergic (Gly/GABA neurons. Since the results obtained with FISH for GlyT2, GAD67, or GlyT2 + GAD67 mRNAs were not significantly different, we concluded that glycine and GABA coexisted in the various projection neurons. After injections in the cervical cord, we found that 29% ± 1 (SEM of the retrogradely labeled neurons in the VM were Gly/GABA (RVM: 43%; CVM: 21%. After lumbar dorsal horn injections 31% ± 3 of the VM neurons were Gly/GABA (RVM: 45%; CVM: 12%, and after lumbar ventral horn injections 25% ± 2 were Gly/GABA (RVM: 35%; CVM: 17%. In addition, we have identified a novel ascending Gly/GABA pathway originating from neurons in the area around the central canal (CC throughout the spinal cord and projecting to the RVM, emphasizing the interaction between the ventromedial medulla and the spinal cord. The present study has now firmly established that GABA and glycine are present in many VM neurons that project to the spinal cord. These neurons strongly influence spinal processing, most notably the inhibition of nociceptive transmission.

  3. Synthesis of new fluorinated analogs of GABA, Pregabalin bioisosteres, and their effects on [(3)H]GABA uptake by rat brain nerve terminals. (United States)

    Borisova, T; Pozdnyakova, N; Shaitanova, E; Gerus, I; Dudarenko, M; Mironets, R; Haufe, G; Kukhar, V


    Fluorinated analogs of natural substances take an essential place in the design of new biologically active compounds. New fluorinated analogs of γ-aminobutyric acid, that is, β-polyfluoroalkyl-GABAs (FGABAs), were synthesized with substituents: β-CF3-β-OH (1), β-CF3 (2); β-CF2CF2H (3). FGABAs are bioisosteres of Pregabalin (Lyrica®, Pfizer's blockbuster drug, β-i-Bu-GABA), and have lipophilicity close to this medicine. The effects of synthesized FGABAs on [(3)H]GABA uptake by isolated rat brain nerve terminals (synaptosomes) were assessed and compared with those of Pregabalin. FGABAs 1-3 (100μM) did not influence the initial velocity of [(3)H]GABA uptake when applied acutely, whereas an increase in this parameter was found after preliminary incubation of FGABAs with synaptosomes. Pregabalin after preliminary incubation with synaptosomes caused unidirectional changes in the initial velocity of [(3)H]GABA uptake. Using specific inhibitors of GAT1 and GAT3, NO-711 and SNAP5114, respectively, the ability of FGABAs 1-3 to influence non-GAT1 and non-GAT3 uptake activity of nerve terminals was analyzed, but no specificity was found. Therefore, new synthesized FGABAs are structural but not functional analogs of GABA (because they did not inhibit synaptosomal [(3)H]GABA uptake). Moreover, FGABAs are able to increase the initial velocity of [(3)H]GABA uptake by synaptosomes, and this effect is higher than that of Pregabalin. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Opioid modulation of GABA release in the rat inferior colliculus

    Directory of Open Access Journals (Sweden)

    Forge Andrew


    Full Text Available Abstract Background The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication. Results Using a perfusion protocol we demonstrate that morphine can inhibit KCl-induced release of [3H]GABA from rat inferior colliculus slices. DAMGO ([D-Ala(2, N-Me-Phe(4, Gly(5-ol]-enkephalin but not DADLE ([D-Ala2, D-Leu5]-enkephalin or U69593 has the same effect as morphine indicating that μ rather than δ or κ opioid receptors mediate this action. [3H]GABA release was diminished by 16%, and this was not altered by the protein kinase C inhibitor bisindolylmaleimide I. Immunostaining of inferior colliculus cryosections shows extensive staining for glutamic acid decarboxylase, more limited staining for μ opiate receptors and relatively few neurons co-stained for both proteins. Conclusion The results suggest that μ-opioid receptor ligands can modify neurotransmitter release in a sub population of GABAergic neurons of the inferior colliculus. This could have important physiological implications in the processing of hearing information and/or other functions attributed to the inferior colliculus such as audiogenic seizures and aversive behaviour.

  5. Knockout of GAD65 has major impact on synaptic GABA synthesized from astrocyte-derived glutamine

    DEFF Research Database (Denmark)

    Walls, Anne Byriel; Eyjolfsson, Elvar M.; Smeland, Olav B.


    65 for maintenance of the highly compartmentalized intracellular and intercellular GABA homeostasis, GAD65 knockout and corresponding wild-type mice were injected with [1-(13)C]glucose and the astrocyte-specific substrate [1,2-(13)C]acetate. Synthesis of GABA from glutamine in the GABAergic synapses...... and hippocampus. The GABA content in both brain regions was reduced by ∼20%. Moreover, it was revealed that GAD65 is crucial for maintenance of biosynthesis of synaptic GABA particularly by direct synthesis from astrocytic glutamine via glutamate. The GAD67 was found to be important for synthesis of GABA from...... glutamine both via direct synthesis and via a pathway involving mitochondrial metabolism. Furthermore, a severe neuronal hypometabolism, involving glycolysis and tricarboxylic acid (TCA) cycle activity, was observed in cerebral cortex of GAD65 knockout mice....

  6. Gamma-amino butyric acid (GABA) synthesis of Lactobacillus in fermentation of defatted rice bran extract (United States)

    Dat, Lai Quoc; Ngan, Tran Thi Kim; Nu, Nguyen Thi Xuan


    This research focused on the synthesis of GABA by Lactobacillus bacteria in fermentation of defatted rice bran extract without adding glutamate. Two strains of Lactobacillus were investigated into capacity of GABA synthesis. Result indicates that, Lactobacillus brevis VTCC - B - 454 exhibited the higher capacity of GABA synthesis in fermentation of defatted rice bran extract than that of Lactobacillus plantarum VTCC - B - 890. Total dissolved solid (TDS), free amino acids (AA) and reducing sugar (RS) contents in fermentation of defatted rice bran extract with two strains also significantly decreased. At pH 5 and 9 %w/w of TDS content in defatted rice bran extract, Lactobacillus brevis VTCC - B - 454 accumulated 2,952 ppm of GABA in 24 hours of fermentation. The result implies that fermentation with Lactobacillus brevis VTCC - B - 454 can be applied for GABA production from defatted rice bran extract.

  7. Acute Immobilization Stress Modulate GABA Release from Rat Olfactory Bulb: Involvement of Endocannabinoids—Cannabinoids and Acute Stress Modulate GABA Release

    Directory of Open Access Journals (Sweden)

    Alejandra Delgado


    Full Text Available We studied the effects of cannabinoids and acute immobilization stress on the regulation of GABA release in the olfactory bulb. Glutamate-stimulated 3H-GABA release was measured in superfused slices. We report that cannabinoids as WIN55, 212-2, methanandamide, and 2-arachidonoylglycerol were able to inhibit glutamate- and KCl-stimulated 3H-GABA release. This effect was blocked by the CB1 antagonist AM281. On the other hand, acute stress was able per se to increase endocannabinoid activity. This effect was evident since the inhibition of stimulated GABA release by acute stress was reversed with AM281 and tetrahydrolipstatin. Inhibition of the endocannabinoid transport or its catabolism showed reduction of GABA release, antagonized by AM281 in control and stressed animals. These results point to endocannabinoids as inhibitory modulators of GABA release in the olfactory bulb acting through an autocrine mechanism. Apparently, stress increases the endocannabinoid system, modulating GABAergic synaptic function in a primary sensory organ.

  8. Endogenous scheduling preferences and congestion

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Small, Kenneth


    We consider the timing of activities through a dynamic model of commuting with congestion, in which workers care solely about leisure and consumption. Implicit preferences for the timing of the commute form endogenously due to temporal agglomeration economies. Equilibrium exists uniquely and is i......We consider the timing of activities through a dynamic model of commuting with congestion, in which workers care solely about leisure and consumption. Implicit preferences for the timing of the commute form endogenously due to temporal agglomeration economies. Equilibrium exists uniquely...... and is indistinguishable from that of a generalized version of the classical Vickrey bottleneck model, based on exogenous trip-timing preferences, but optimal policies differ: the Vickrey model will misstate the benefits of a capacity increase, it will underpredict the benefits of congestion pricing, and pricing may make...

  9. Endogenous Methanol Regulates Mammalian Gene Activity (United States)

    Komarova, Tatiana V.; Petrunia, Igor V.; Shindyapina, Anastasia V.; Silachev, Denis N.; Sheshukova, Ekaterina V.; Kiryanov, Gleb I.; Dorokhov, Yuri L.


    We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH) converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP) and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis. PMID:24587296

  10. Exogenous and endogenous cannabimimetic metabolites

    Energy Technology Data Exchange (ETDEWEB)

    Di Marzo, V.; Bisogno, T.; Melck, D. [CNR, Arco Felice, Naples (Italy). Ist. per la Chimica di Molecole di Interesse Biologico; De Petrocellis, L. [CNR, Arco Felice, Naples (Italy). Ist. di Cibernetica


    Only a few discoveries in the fields of pharmacology and physiology have benefited from the work of organic and synthetic chemists like the identification of the existence and possible physiological function of the `endogenous cannabinoid system`. The review emphasizes the key role played by chemists in this area of pharmacological research, and highlights the possible industrial implications of the discovery of cannabimimetic metabolites and of their mechanism of action.

  11. GABA(A receptor α subunits differentially contribute to diazepam tolerance after chronic treatment.

    Directory of Open Access Journals (Sweden)

    Christiaan H Vinkers

    Full Text Available Within the GABA(A-receptor field, two important questions are what molecular mechanisms underlie benzodiazepine tolerance, and whether tolerance can be ascribed to certain GABA(A-receptor subtypes.We investigated tolerance to acute anxiolytic, hypothermic and sedative effects of diazepam in mice exposed for 28-days to non-selective/selective GABA(A-receptor positive allosteric modulators: diazepam (non-selective, bretazenil (partial non-selective, zolpidem (α(1 selective and TPA023 (α(2/3 selective. In-vivo binding studies with [(3H]flumazenil confirmed compounds occupied CNS GABA(A receptors.Chronic diazepam treatment resulted in tolerance to diazepam's acute anxiolytic, hypothermic and sedative effects. In mice treated chronically with bretazenil, tolerance to diazepam's anxiolytic and hypothermic, but not sedative, effects was seen. Chronic zolpidem treatment resulted in tolerance to diazepam's hypothermic effect, but partial anxiolytic tolerance and no sedative tolerance. Chronic TPA023 treatment did not result in tolerance to diazepam's hypothermic, anxiolytic or sedative effects.OUR DATA INDICATE THAT: (i GABA(A-α(2/α(3 subtype selective drugs might not induce tolerance; (ii in rodents quantitative and temporal variations in tolerance development occur dependent on the endpoint assessed, consistent with clinical experience with benzodiazepines (e.g., differential tolerance to antiepileptic and anxiolytic actions; (iii tolerance to diazepam's sedative actions needs concomitant activation of GABA(A-α(1/GABA(A-α(5 receptors. Regarding mechanism, in-situ hybridization studies indicated no gross changes in expression levels of GABA(A α(1, α(2 or α(5 subunit mRNA in hippocampus or cortex. Since selective chronic activation of either GABA(A α(2, or α(3 receptors does not engender tolerance development, subtype-selective GABA(A drugs might constitute a promising class of novel drugs.

  12. Anaesthetic impairment of immune function is mediated via GABA(A receptors.

    Directory of Open Access Journals (Sweden)

    Daniel W Wheeler


    Full Text Available GABA(A receptors are members of the Cys-loop family of neurotransmitter receptors, proteins which are responsible for fast synaptic transmission, and are the site of action of wide range of drugs. Recent work has shown that Cys-loop receptors are present on immune cells, but their physiological roles and the effects of drugs that modify their function in the innate immune system are currently unclear. We are interested in how and why anaesthetics increase infections in intensive care patients; a serious problem as more than 50% of patients with severe sepsis will die. As many anaesthetics act via GABA(A receptors, the aim of this study was to determine if these receptors are present on immune cells, and could play a role in immunocompromising patients.We demonstrate, using RT-PCR, that monocytes express GABA(A receptors constructed of α1, α4, β2, γ1 and/or δ subunits. Whole cell patch clamp electrophysiological studies show that GABA can activate these receptors, resulting in the opening of a chloride-selective channel; activation is inhibited by the GABA(A receptor antagonists bicuculline and picrotoxin, but not enhanced by the positive modulator diazepam. The anaesthetic drugs propofol and thiopental, which can act via GABA(A receptors, impaired monocyte function in classic immunological chemotaxis and phagocytosis assays, an effect reversed by bicuculline and picrotoxin.Our results show that functional GABA(A receptors are present on monocytes with properties similar to CNS GABA(A receptors. The functional data provide a possible explanation as to why chronic propofol and thiopental administration can increase the risk of infection in critically ill patients: their action on GABA(A receptors inhibits normal monocyte behaviour. The data also suggest a potential solution: monocyte GABA(A receptors are insensitive to diazepam, thus the use of benzodiazepines as an alternative anesthetising agent may be advantageous where infection is a life

  13. Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus

    Directory of Open Access Journals (Sweden)

    Paul David Whissell


    Full Text Available Cholecystokinin (CCK- and parvalbumin (PV-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behaviour. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV than they were in corresponding primary areas (V1, S1, M1 and Aud1. The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favour the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labelling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

  14. GABA(B) Receptor Agonism as a Novel Therapeutic Modality in the Treatment of Gastroesophageal Reflux Disease

    NARCIS (Netherlands)

    Lehmann, Anders; Jensen, Jörgen M.; Boeckxstaens, Guy E.


    Defined pharmacologically by its insensitivity to the GABA(A) antagonist bicuculline and sensitivity to the GABA analogue baclofen, the G protein-linked gamma-aminobutyric acid type B (GABA(B)) receptor couples to adenylyl cyclase, voltage-gated calcium channels, and inwardly-rectifying potassium


    NARCIS (Netherlands)



    The effects of the anti-epileptic drugs valproic acid and gamma-vinyl-GABA (vigabatrin) on the extracellular content of GABA was determined by microdialysis. Probes were implanted in the substantia nigra reticulata (SNR) of rats. It was found that gamma-vinyl-GABA (1000 mg/kg) induced a 4-6-fold

  16. Melatonin in Children with Autism Spectrum Disorders: Endogenous and Pharmacokinetic Profiles in Relation to Sleep (United States)

    Goldman, Suzanne E.; Adkins, Karen W.; Calcutt, M. Wade; Carter, Melissa D.; Goodpaster, Robert L.; Wang, Lily; Shi, Yaping; Burgess, Helen J.; Hachey, David L.; Malow, Beth A.


    Supplemental melatonin has been used to treat sleep onset insomnia in children with autism spectrum disorders (ASD), although the mechanism of action is uncertain. We assessed endogenous and supplemental melatonin profiles in relation to sleep in nine children with ASD. In endogenous samples, maximal melatonin concentration (C[subscript max]) and…

  17. Interaction of GABA-mimetics with the taurine transporter (TauT, Slc6a6) in hyperosmotic treated Caco-2, LLC-PK1 and rat renal SKPT cells

    DEFF Research Database (Denmark)

    Rasmussen, Rune Nørgaard; Lagunas, Candela; Plum, Jakob


    . Uptake of the GABA-mimetics gaboxadol and vigabatrin was investigated in SKPT cells, and quantified by liquid scintillation or HPLC-MS/MS analysis, respectively. The uptake rate of [(3)H]-taurine was Na(+) and Cl(-) and concentration dependent with taurine with an apparent Vmax of 6.3±1.6pmolcm(-2)min(-1...

  18. Pharmacology of morphine and morphine-3-glucuronide at opioid, excitatory amino acid, GABA and glycine binding sites

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, S.E.; Smith, M.T. (Department of Pharmacy, The University of Queensland (Australia)); Dood, P.R. (Clinical Research Centre, Royal Brisbane Hospital Foundation, Brisbane (Australia))


    Morphine in high doses and its major metabolite, morphine-3-glucuronide, cause CNS excitation following intrathecal and intracerebroventricular administration by an unknown mechanism. This study investigated whether morphine and morphine-3-glucuronide interact at major excitatory (glutamate), major inhibitory (GABA or glycine), or opioid binding sites. Homogenate binding assays were performed using specific radioligands. At opioid receptors, morphine-3-glucuronide and morphine caused an equipotent sodium shift, consistent with morphine-3-glucuronide behaving as an agonist. This suggests that morphine-3-glucuronide-mediated excitation is not caused by an interaction at opioid receptors. Morphine-3-glucuronide and morphine caused a weak inhibition of the binding of [sup 3]H-MK801 (non-competitive antagonist) and [sup 125]I-ifenprodil (polyamine site antagonist), but at unphysiologically high concentrations. This suggests that CNS excitation would not result from an interaction of morphine-3-glucuronide and high-dose morphine with these sites on the NMDA receptor. Morphine-3-glucuronide and morphine inhibited the binding of [sup 3]H-muscimol (GABA receptor agonist), [sup 3]H-diazepam and [sup 3]H-flunitraxepam (benzodiazepine agonists) binding very weakly, suggesting the excitatory effects of morphine-3-glucuronide and high-dose morphine are not elicited through GABA[sub A] receptors. Morphine-3-glucuronide and high-dose morphine did not prevent re-uptake of glutamate into presynaptic nerve terminals. In addition, morphine-3-glucuronide and morphine did not inhibit the binding of [sup 3]H-strychnine (glycine receptor antagonist) to synaptic membranes prepared from bovine spinal cord. It is concluded that excitation caused by high-dose morphine and morphine-3-glucuronide is not mediated by an interaction with postsynaptic amino acid receptors. (au) (30 refs.).

  19. Hypocalcemia reduces endogenous glucose production in hyperketonemic sheep. (United States)

    Schlumbohm, C; Harmeyer, J


    In previous experiments it has been shown that hyperketonemia lowered plasma glucose concentration in sheep and depressed endogenous glucose production by approximately 30%. This facilitates the onset of pregnancy toxemia. In the last trimester of gestation, hyperketonemia in sheep is often associated with hypocalcemia. There is an indication that hypocalcemia exerts an additional depressive effect on endogenous glucose production. The present study was undertaken to examine the effect in sheep of hypocalcemia on endogenous glucose production in the presence of normo- and hyperketonemia. The experiments were carried out with seven multiparous sheep during three different reproductive states, i.e., during pregnancy (10 +/- 8 d prepartum), during lactation (21 +/- 8 d postpartum), and 4 wk after weaning of the lambs. Concentration of glucose in plasma, turnover of glucose and the rate constant of glucose turnover were measured by isotope dilution during normo- and hypocalcemia and in the presence of normal and elevated beta-hydroxybutyrate (BHB) concentrations. Hypocalcemia was induced by i.v. infusions of Na2EDTA. Hyperketonemia was maintained by i.v. infusion of DL-beta-hydroxybutyrate. The experiments showed that induction of hypocalcemia: 1) induced a decline in plasma glucose concentration in all reproductive states during normo- and hyperketonemia and 2) significantly lowered endogenous production of glucose in nonpregnant hyperketonemic and in lactating normoketonemic ewes. Pregnant normoketonemic ewes were able to compensate for the hypoglycemic effect of hypocalcemia and to keep endogenous production at the normocalcemic level. We concluded that hypocalcemia does not promote the onset of pregnancy toxemia per se but will facilitate the development of the disease when it is present in combination with hyperketonemia.

  20. Stable isotope dilution HILIC-MS/MS method for accurate quantification of glutamic acid, glutamine, pyroglutamic acid, GABA and theanine in mouse brain tissues. (United States)

    Inoue, Koichi; Miyazaki, Yasuto; Unno, Keiko; Min, Jun Zhe; Todoroki, Kenichiro; Toyo'oka, Toshimasa


    In this study, we developed the stable isotope dilution hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS) technique for the accurate, reasonable and simultaneous quantification of glutamic acid (Glu), glutamine (Gln), pyroglutamic acid (pGlu), γ-aminobutyric acid (GABA) and theanine in mouse brain tissues. The quantification of these analytes was accomplished using stable isotope internal standards and the HILIC separating mode to fully correct the intramolecular cyclization during the electrospray ionization. It was shown that linear calibrations were available with high coefficients of correlation (r(2)  > 0.999, range from 10 pmol/mL to 50 mol/mL). For application of the theanine intake, the determination of Glu, Gln, pGlu, GABA and theanine in the hippocampus and central cortex tissues was performed based on our developed method. In the region of the hippocampus, the concentration levels of Glu and pGlu were significantly reduced during reality-based theanine intake. Conversely, the concentration level of GABA increased. This result showed that transited theanine has an effect on the metabolic balance of Glu analogs in the hippocampus. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Use of sourdough fermentation and pseudo-cereals and leguminous flours for the making of a functional bread enriched of gamma-aminobutyric acid (GABA). (United States)

    Coda, Rossana; Rizzello, Carlo Giuseppe; Gobbetti, Marco


    Lactobacillus plantarum C48 and Lactococcus lactis subsp. lactis PU1, previously selected for the biosynthesis of gamma-aminobutyric acid (GABA), were used for sourdough fermentation of cereal, pseudo-cereal and leguminous flours. Chickpea, amaranth, quinoa and buckwheat were the flours most suitable to be enriched of GABA. The parameters of sourdough fermentation were optimized. Addition of 0.1mM pyridoxal phosphate, dough yield of 160, inoculum of 5 x 10(7)CFU/g of starter bacteria and fermentation for 24h at 30 degrees C were found to be the optimal conditions. A blend of buckwheat, amaranth, chickpea and quinoa flours (ratio 1:1:5.3:1) was selected and fermented with baker's yeast (non-conventional flour bread, NCB) or with Lb. plantarum C48 sourdough (non-conventional flour sourdough bread, NCSB) and compared to baker's yeast started wheat flour bread (WFB). NCSB had the highest concentration of free amino acids and GABA (ca. 4467 and 504 mg/kg, respectively). The concentration of phenolic compounds and antioxidant activity of NCSB bread was the highest, as well as the rate of in vitro starch hydrolysis was the lowest. Texture analysis showed that sourdough fermentation enhances several characteristics of NCSB with respect to NCB, thus approaching the features of WFB. Sensory analysis showed that sourdough fermentation allowed to get good palatability and overall taste appreciation. (c) 2009 Elsevier B.V. All rights reserved.

  2. Protein kinase Cdelta regulates ethanol intoxication and enhancement of GABA-stimulated tonic current. (United States)

    Choi, Doo-Sup; Wei, Weizheng; Deitchman, J Kevin; Kharazia, Viktor N; Lesscher, Heidi M B; McMahon, Thomas; Wang, Dan; Qi, Zhan-Heng; Sieghart, Werner; Zhang, Chao; Shokat, Kevan M; Mody, Istvan; Messing, Robert O


    Ethanol alters the distribution and abundance of PKCdelta in neural cell lines. Here we investigated whether PKCdelta also regulates behavioral responses to ethanol. PKCdelta(-/-) mice showed reduced intoxication when administered ethanol and reduced ataxia when administered the nonselective GABA(A) receptor agonists pentobarbital and pregnanolone. However, their response to flunitrazepam was not altered, suggesting that PKCdelta regulates benzodiazepine-insensitive GABA(A) receptors, most of which contain delta subunits and mediate tonic inhibitory currents in neurons. Indeed, the distribution of PKCdelta overlapped with GABA(A) delta subunits in thalamus and hippocampus, and ethanol failed to enhance tonic GABA currents in PKCdelta(-/-) thalamic and hippocampal neurons. Moreover, using an ATP analog-sensitive PKCdelta mutant in mouse L(tk(-)) fibroblasts that express alpha4beta3delta GABA(A) receptors, we found that ethanol enhancement of GABA currents was PKCdelta-dependent. Thus, PKCdelta enhances ethanol intoxication partly through regulation of GABA(A) receptors that contain delta subunits and mediate tonic inhibitory currents. These findings indicate that PKCdelta contributes to a high level of behavioral response to ethanol, which is negatively associated with risk of developing an alcohol use disorder in humans.

  3. Hypothesis/review: contribution of putrescine to 4-aminobutyrate (GABA) production in response to abiotic stress. (United States)

    Shelp, Barry J; Bozzo, Gale G; Trobacher, Christopher P; Zarei, Adel; Deyman, Kristen L; Brikis, Carolyne J


    4-Aminobutyrate (GABA) accumulates in various plant parts, including bulky fruits such as apples, in response to abiotic stress. It is generally believed that the GABA is derived from glutamate, although a contribution from polyamines is possible. Putrescine, but not spermidine and spermine, generally accumulates in response to the genetic manipulation of polyamine biosynthetic enzymes and abiotic stress. However, the GABA levels in stressed plants are influenced by processes other than putrescine availability. It is hypothesized that the catabolism of putrescine to GABA is regulated by a combination of gene-dependent and -independent processes. The expression of several putative diamine oxidase genes is weak, but highly stress-inducible in certain tissues of Arabidopsis. In contrast, candidate genes that encode 4-aminobutyraldehyde dehydrogenase are highly constitutive, but not stress inducible. Changes in O(2) availability and cellular redox balance due to stress may directly influence the activities of diamine oxidase and 4-aminobutyraldehyde dehydrogenase, thereby restricting GABA formation. Apple fruit is known to accumulate GABA under controlled atmosphere storage and therefore could serve as a model system for investigating the relative contribution of putrescine and glutamate to GABA production. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  4. Imbalance between Glutamate and GABA in Fmr1 Knockout Astrocytes Influences Neuronal Development

    Directory of Open Access Journals (Sweden)

    Lu Wang


    Full Text Available Fragile X syndrome (FXS is a form of inherited mental retardation that results from the absence of the fragile X mental retardation protein (FMRP, the product of the Fmr1 gene. Numerous studies have shown that FMRP expression in astrocytes is important in the development of FXS. Although astrocytes affect neuronal dendrite development in Fmr1 knockout (KO mice, the factors released by astrocytes are still unclear. We cultured wild type (WT cortical neurons in astrocyte-conditioned medium (ACM from WT or Fmr1 KO mice. Immunocytochemistry and Western blotting were performed to detect the dendritic growth of both WT and KO neurons. We determined glutamate and γ-aminobutyric acid (GABA levels using high-performance liquid chromatography (HPLC. The total neuronal dendritic length was reduced when cultured in the Fmr1 KO ACM. This neurotoxicity was triggered by an imbalanced release of glutamate and GABA from Fmr1 KO astrocytes. We found increased glutaminase and GABA transaminase (GABA-T expression and decreased monoamine oxidase B expression in Fmr1 KO astrocytes. The elevated levels of glutamate contributed to oxidative stress in the cultured neurons. Vigabatrin (VGB, a GABA-T inhibitor, reversed the changes caused by glutamate and GABA release in Fmr1 KO astrocytes and the abnormal behaviors in Fmr1 KO mice. Our results indicate that the imbalance in the astrocytic glutamate and GABA release may be involved in the neuropathology and the underlying symptoms of FXS, and provides a therapeutic target for treatment.

  5. On the origins of endogenous thoughts. (United States)

    Tillas, Alexandros


    Endogenous thoughts are thoughts that we activate in a top-down manner or in the absence of the appropriate stimuli. We use endogenous thoughts to plan or recall past events. In this sense, endogenous thinking is one of the hallmarks of our cognitive lives. In this paper, I investigate how it is that we come to possess endogenous control over our thoughts. Starting from the close relation between language and thinking, I look into speech production-a process motorically controlled by the inferior frontal gyrus (IFG). Interestingly, IFG is also closely related to silent talking, as well as volition. The connection between IFG and volition is important given that endogenous thoughts are or at least greatly resemble voluntary actions. Against this background, I argue that IFG is key to understanding the origins of conscious endogenous thoughts. Furthermore, I look into goal-directed thinking and show that IFG plays a key role also in unconscious endogenous thinking.

  6. Microtransplantation of cellular membranes from squid stellate ganglion reveals ionotropic GABA receptors. (United States)

    Conti, Luca; Limon, Agenor; Palma, Eleonora; Miledi, Ricardo


    The squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. While the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. In this study we investigated whether γ-aminobutyric acid (GABA) activates neurotransmitter receptors in stellate ganglia membranes. To overcome the low abundance of GABA-like mRNAs in invertebrates and the low expression of GABA in cephalopods, we used a two-electrode voltage clamp technique to determine if Xenopus laevis oocytes injected with cell membranes from squid stellate ganglia responded to GABA. Using this method, membrane patches containing proteins and ion channels from the squid's stellate ganglion were incorporated into the surface of oocytes. We demonstrated that GABA activates membrane receptors in cellular membranes isolated from squid stellate ganglia. Using the same approach, we were able to record native glutamate-evoked currents. The squid's GABA receptors showed an EC(50) of 98 μmol l(-1) to GABA and were inhibited by zinc (IC(50) = 356 μmol l(-1)). Interestingly, GABA receptors from the squid were only partially blocked by bicuculline. These results indicate that the microtransplantation of native cell membranes is useful to identify and characterize scarce membrane proteins. Moreover, our data also support the role of GABA as an ionotropic neurotransmitter in cephalopods, acting through chloride-permeable membrane receptors.

  7. Ultrastructure of GABA- and tachykinin-immunoreactive neurons in the lower division of the central body of the desert locust

    Directory of Open Access Journals (Sweden)

    Uwe Homberg


    Full Text Available The central complex, a group of neuropils spanning the midline of the insect brain, plays a key role in spatial orientation and navigation. In the desert locust and other species, many neurons of the central complex are sensitive to the oscillation plane of polarized light above the animal and are likely involved in the coding of compass directions derived from the polarization pattern of the sky. Polarized light signals enter the locust central complex primarily through two types of -aminobutyric acid (GABA-immunoreactive tangential neurons, termed TL2 and TL3 that innervate specific layers of the lower division of the central body (CBL. Candidate postsynaptic partners are columnar neurons (CL1 connecting the CBL to the protocerebral bridge. Subsets of CL1 neurons are immunoreactive to antisera against locustatachykinin (LomTK. To better understand the synaptic connectivities of tangential and columnar neurons in the CBL, we studied its ultrastructural organization in the desert locust, both with conventional electron microscopy and in preparations immunolabeled for GABA or LomTK. Neuronal profiles in the CBL were rich in mitochondria and vesicles. Three types of vesicles were distinguished: small clear vesicles with diameters of 20-40 nm, dark dense-core vesicles (diameter 70-120 nm, and granular dense-core vesicles (diameter 70-80 nm. Neurons were connected via divergent dyads and, less frequently, through convergent dyads. GABA-immunoreactive neurons contained small clear vesicles and small numbers of dark dense core vesicles. They had both pre- and postsynaptic contacts but output synapses were observed more frequently than input synapses. LomTK immunostaining was concentrated on large granular vesicles; neurons had pre- and postsynaptic connections often with neurons assumed to be GABAergic. The data suggest that GABA-immunoreactive tangential neurons provide signals to postsynaptic neurons in the CBL, including LomTK-immunolabeled CL1

  8. GABA metabolism pathway genes, UGA1 and GAD1, regulate replicative lifespan in Saccharomycescerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Kamei, Yuka; Tamura, Takayuki [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Yoshida, Ryo [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ohta, Shinji [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Fukusaki, Eiichiro [Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Mukai, Yukio, E-mail: [Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)


    Highlights: {yields}We demonstrate that two genes in the yeast GABA metabolism pathway affect aging. {yields} Deletion of the UGA1 or GAD1 genes extends replicative lifespan. {yields} Addition of GABA to wild-type cultures has no effect on lifespan. {yields} Intracellular GABA levels do not differ in longevity mutants and wild-type cells. {yields} Levels of tricarboxylic acid cycle intermediates positively correlate with lifespan. -- Abstract: Many of the genes involved in aging have been identified in organisms ranging from yeast to human. Our previous study showed that deletion of the UGA3 gene-which encodes a zinc-finger transcription factor necessary for {gamma}-aminobutyric acid (GABA)-dependent induction of the UGA1 (GABA aminotransferase), UGA2 (succinate semialdehyde dehydrogenase), and UGA4 (GABA permease) genes-extends replicative lifespan in the budding yeast Saccharomycescerevisiae. Here, we found that deletion of UGA1 lengthened the lifespan, as did deletion of UGA3; in contrast, strains with UGA2 or UGA4 deletions exhibited no lifespan extension. The {Delta}uga1 strain cannot deaminate GABA to succinate semialdehyde. Deletion of GAD1, which encodes the glutamate decarboxylase that converts glutamate into GABA, also increased lifespan. Therefore, two genes in the GABA metabolism pathway, UGA1 and GAD1, were identified as aging genes. Unexpectedly, intracellular GABA levels in mutant cells (except for {Delta}uga2 cells) did not differ from those in wild-type cells. Addition of GABA to culture media, which induces transcription of the UGA structural genes, had no effect on replicative lifespan of wild-type cells. Multivariate analysis of {sup 1}H nuclear magnetic resonance spectra for the whole-cell metabolite levels demonstrated a separation between long-lived and normal-lived strains. Gas chromatography-mass spectrometry analysis of identified metabolites showed that levels of tricarboxylic acid cycle intermediates positively correlated with lifespan

  9. Novel GABA agonists depress the reward effect of lateral hypothalamic stimulation in rats. (United States)

    Backus, L I; Stellar, J R; Jacob, J; Hesse, G W; Shashoua, V E


    Rats were given systemic injections of one of a series of novel GABA compounds which can penetrate the blood-brain barrier to release GABA into the brain. They were then tested on lateral hypothalamic self-stimulation behavior using a rate-frequency paradigm to discriminate effects on reward from those on motor/performance. Both reward and, to a lesser extent, motor/performance impairments were found with all GABA compounds. In more extensive testing with one compound, LG2, no differences in the effects of three salts (acetate, ascorbate, and tartarate) were found except that the tartarate salt effects decayed more rapidly.

  10. GAD65 is essential for synthesis of GABA destined for tonic inhibition regulating epileptiform activity

    DEFF Research Database (Denmark)

    Walls, Anne B; Nilsen, Linn Hege; Eyjolfsson, Elvar M


    ABSTRACT: GABA is synthesized from glutamate by glutamate decarboxylase (GAD), which exists in two isoforms, that is, GAD65 and GAD67. In line with GAD65 being located in the GABAergic synapse, several studies have demonstrated that this isoform is important during sustained synaptic transmission....... In contrast, the functional significance of GAD65 in the maintenance of GABA destined for extrasynaptic tonic inhibition is less well studied. Using GAD65-/- and wild type GAD65+/+ mice, this was examined employing the cortical wedge preparation, a model suitable for investigating extrasynaptic GABA...

  11. Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex

    Energy Technology Data Exchange (ETDEWEB)

    Malatynska, E.; Knapp, R.J.; Ikeda, M.; Yamamura, H.I.


    Convulsive seizures are a potential side effect of antidepressant drug treatment and can be produced by all classes of antidepressants. It is also know that some convulsant and anticonvulsant drug actions are mediated by the GABA-receptor chloride-ionophore complex. Drugs acting at this complex appear to induce convulsions by inhibiting chloride conductance through the associated chloride channel. Using the method of GABA-stimulated /sup 36/Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs can inhibit the GABA-receptor chloride uptake, and that the degree of chloride channel inhibition by these drugs correlates with the frequency of convulsive seizures induced by them.

  12. Effects of focal brain cooling on extracellular concentrations of neurotransmitters in patients with epilepsy. (United States)

    Nomura, Sadahiro; Inoue, Takao; Imoto, Hirochika; Suehiro, Eiichi; Maruta, Yuichi; Hirayama, Yuya; Suzuki, Michiyasu


    Brain hypothermia controls epileptic discharge and reduces extracellular concentrations of glutamate (Glu), an excitatory neurotransmitter. We aimed to determine the effects of focal brain cooling (FBC) on levels of γ-aminobutyric acid (GABA), which is a major inhibitory neurotransmitter. The relationship between Glu or GABA concentrations and the severity of epileptic symptoms was also analyzed. Patients with intractable epilepsy underwent FBC at lesionectomized (n = 11) or hippocampectomized (n = 8) regions at 15°C for 30 min using custom-made cooling devices. Concentrations of Glu (n = 18) and GABA (n = 12) were measured in extracellular fluid obtained through microdialysis using high-performance liquid chromatography (HPLC). The reduction rate of neurotransmitter levels and its relationship with electrocorticography (ECoG) signal changes in response to FBC were measured. We found no relationship between the concentrations of Glu or GABA and seizure severity. There was a significant decrease in the concentration of Glu to 66.3% of control levels during the cooling period (p = 0.001). This rate of reduction correlated with ECoG power (r(2) = 0.68). Cortical and hippocampal GABA levels significantly (p = 0.02) and nonsignificantly decreased to 47.7% and 32.4% of control levels, respectively. However, the rate of this reduction did not correlate with ECoG (r(2) = 0.11). Although the decrease in hippocampal GABA levels was not significant due to wide variations in its concentration, the levels of cortical GABA and Glu were decreased following FBC. FBC suppresses epileptic discharge and the release of both excitatory and inhibitory neurotransmitters. The reduction in Glu levels further contributes to the reduction in epileptic discharge. However, the reduction in the levels of GABA has no impact on ECoG. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  13. Measurement of endogenous subcellular concentration of steroids in tissue


    Poortman, J.; Landeghem, A.A.J. van; Helmond-Agema, A.; Thussen, J.H.H.


    A reliable method for the extraction of steroid hormones from human uterine tissue and the subsequent measurement of these hormones in the subcellular compartments by radioimmunoassay is described. Extraction of radioactive steroid hormones from in vivo labelled human uterine tissue by different methods reveals that an almost quantitative extraction of steroid hormones from the nuclear fraction is obtained by sonication in ethanol-acetone. Extraction of steroid hormones with diethylether from...

  14. Measurement of endogenous subcellular concentration of steroids in tissue

    NARCIS (Netherlands)

    Poortman, J.; Landeghem, A.A.J. van; Helmond-Agema, A.; Thussen, J.H.H.


    A reliable method for the extraction of steroid hormones from human uterine tissue and the subsequent measurement of these hormones in the subcellular compartments by radioimmunoassay is described. Extraction of radioactive steroid hormones from in vivo labelled human uterine tissue by different

  15. A possible role of the non-GAT1 GABA transporters in transfer of GABA from GABAergic to glutamatergic neurons in mouse cerebellar neuronal cultures

    DEFF Research Database (Denmark)

    Suñol, C; Babot, Z; Cristòfol, R


    Cultures of dissociated cerebellum from 7-day-old mice were used to investigate the mechanism involved in synthesis and cellular redistribution of GABA in these cultures consisting primarily of glutamatergic granule neurons and a smaller population of GABAergic Golgi and stellate neurons. The dis......Cultures of dissociated cerebellum from 7-day-old mice were used to investigate the mechanism involved in synthesis and cellular redistribution of GABA in these cultures consisting primarily of glutamatergic granule neurons and a smaller population of GABAergic Golgi and stellate neurons....... The distribution of GAD, GABA and the vesicular glutamate transporter VGlut-1 was assessed using specific antibodies combined with immunofluorescence microscopy. Additionally, tiagabine, SKF 89976-A, betaine, beta-alanine, nipecotic acid and guvacine were used to inhibit the GAT1, betaine/GABA (BGT1), GAT2 and GAT...... neurons constituting the majority of the cells. GABA uptake exhibited the kinetics of high affinity transport and could be partly (20%) inhibited by betaine (IC(50) 142 microM), beta-alanine (30%) and almost fully (90%) inhibited by SKF 89976-A (IC(50) 0.8 microM) or nipecotic acid and guvacine at 1 m...

  16. Endogenous Receptor Agonists: Resolving Inflammation

    Directory of Open Access Journals (Sweden)

    Gerhard Bannenberg


    Full Text Available Controlled resolution or the physiologic resolution of a well-orchestrated inflammatory response at the tissue level is essential to return to homeostasis. A comprehensive understanding of the cellular and molecular events that control the termination of acute inflammation is needed in molecular terms given the widely held view that aberrant inflammation underlies many common diseases. This review focuses on recent advances in the understanding of the role of arachidonic acid and ω-3 polyunsaturated fatty acids (PUFA–derived lipid mediators in regulating the resolution of inflammation. Using a functional lipidomic approach employing LC-MS-MS–based informatics, recent studies, reviewed herein, uncovered new families of local-acting chemical mediators actively biosynthesized during the resolution phase from the essential fatty acids eicosapentaenoic acid (EPA and docosahexaenoic acid (DHA. These new families of local chemical mediators are generated endogenously in exudates collected during the resolution phase, and were coined resolvins and protectins because specific members of these novel chemical families control both the duration and magnitude of inflammation in animal models of complex diseases. Recent advances on the biosynthesis, receptors, and actions of these novel anti-inflammatory and proresolving lipid mediators are reviewed with the aim to bring to attention the important role of specific lipid mediators as endogenous agonists in inflammation resolution.

  17. Endogeneity in prison risk classification. (United States)

    Shermer, Lauren O'Neill; Bierie, David M; Stock, Amber


    Security designation tools are a key feature of all prisons in the United States, intended as objective measures of risk that funnel inmates into security levels-to prison environments varying in degree of intrusiveness, restriction, dangerousness, and cost. These tools are mostly (if not all) validated by measuring inmates on a set of characteristics, using scores from summations of that information to assign inmates to prisons of varying security level, and then observing whether inmates assumed more risky did in fact offend more. That approach leaves open the possibility of endogeneity--that the harsher prisons are themselves bringing about higher misconduct and thus biasing coefficients assessing individual risk. The current study assesses this potential bias by following an entry cohort of inmates to more than 100 facilities in the Federal Bureau of Prisons (BOP) and exploiting the substantial variation in classification scores within a given prison that derive from systematic overrides of security-level designations for reasons not associated with risk of misconduct. By estimating pooled models of misconduct along with prison-fixed effects specifications, the data show that a portion of the predictive accuracy thought associated with the risk-designation tool used in BOP was a function of facility-level contamination (endogeneity).

  18. Endogenous Retroviruses in Domestic Animals (United States)

    Garcia-Etxebarria, Koldo; Sistiaga-Poveda, Maialen; Jugo, Begoña Marina


    Endogenous retroviruses (ERVs) are genomic elements that are present in a wide range of vertebrates. Although the study of ERVs has been carried out mainly in humans and model organisms, recently, domestic animals have become important, and some species have begun to be analyzed to gain further insight into ERVs. Due to the availability of complete genomes and the development of new computer tools, ERVs can now be analyzed from a genome-wide viewpoint. In addition, more experimental work is being carried out to analyze the distribution, expression and interplay of ERVs within a host genome. Cats, cattle, chicken, dogs, horses, pigs and sheep have been scrutinized in this manner, all of which are interesting species in health and economic terms. Furthermore, several studies have noted differences in the number of endogenous retroviruses and in the variability of these elements among different breeds, as well as their expression in different tissues and the effects of their locations, which, in some cases, are near genes. These findings suggest a complex, intriguing relationship between ERVs and host genomes. In this review, we summarize the most important in silico and experimental findings, discuss their implications and attempt to predict future directions for the study of these genomic elements. PMID:25132796

  19. Endogenous sex hormones and risk of venous thromboembolism in women and men

    DEFF Research Database (Denmark)

    Holmegard, Haya N; Nordestgaard, B G; Schnohr, P


    BACKGROUND: Use of oral contraceptives with estrogen and hormone replacement therapy with estrogen or testosterone are associated with increased risk of venous thromboembolism (VTE). However, whether endogenous estradiol and testosterone concentrations are also associated with risk of VTE...

  20. Painful tonic heat stimulation induces GABA accumulation in the prefrontal cortex in man

    DEFF Research Database (Denmark)

    Kupers, Ron; Danielsen, Else R; Kehlet, Henrik


    Relatively little is known on pain-induced neurotransmitter release in the human cerebral cortex. We used proton magnetic resonance spectroscopy (1H-MRS) during tonic painful heat stimulation to test the hypothesis of increases in both glutamate and GABA, two neurotransmitters with a key role...... in pain processing. Using a 3T MR scanner, we acquired spectra from the rostral anterior cingulate cortex (rACC) in 13 healthy right-handed subjects at rest and during painful heat stimulation. The painful stimulus consisted of a suprathreshold painful tonic heat pulse, which was delivered to the right...... that GABA is released in the human cerebral cortex during painful stimulation. The results are in line with animal findings on the role of GABA in pain processing and with studies in humans showing analgesic efficacy of GABA-related drugs in clinical pain conditions....

  1. Gramicidin-perforated patch revealed depolarizing effect of GABA in cultured frog melanotrophs

    National Research Council Canada - National Science Library

    Frank Le Foll; Hélène Castel; Olivier Soriani; Hubert Vaudry; Lionel Cazin


    ...ˆ’ ] i ) in cultured frog melanotrophs. In the gramicidin-perforated patch configuration, 1 μM GABA caused a depolarization associated with an action potential discharge and a slight fall of membrane resistance...

  2. GABA(A) receptors determine the temporal dynamics of memory retention. (United States)

    McNally, Gavan P; Augustyn, Katarzyna A; Richardson, Rick


    Four experiments studied the role of GABA(A) receptors in the temporal dynamics of memory retention. Memory for an active avoidance response was a nonmonotonic function of the retention interval. When rats were tested shortly (2 min) or some time (24 h) after training, retention was excellent, but when they were tested at intermediate intervals (1-4 h), retention was poor. Activity at GABA(A) receptors was critical for impairing memory retention at the intermediate intervals because injection of the GABA(A) receptor partial inverse agonist FG7142 prior to test significantly improved performance. These retention enhancing effects of FG7142 were dose-dependent and not due to any nonspecific effects of FG7142 on activity. Our results suggest that the temporal dynamics of memory retention may be caused by variations in neurotransmission through the GABA(A) receptor in the post-training period.

  3. Effect of THIP and SL 76002, two clinically experimented GABA-mimetic compounds, on anterior pituitary GABA receptors and prolactin secretion in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Apud, J.A.; Masotto, C.; Racagni, G.


    In the present study, the ability of three direct GABA agonists, muscimol, THIP and SL 76002 to displace /sup 3/H-GABA binding from anterior pituitary and medio-basal hypothalamus membranes was evaluated. Further, the effect of both THIP and SL 76002 on baseline prolactin levels or after stimulation of hormone release with haloperidol has been also studied. Either muscimol, THIP or SL 76002 have shown to posses 7-, 7- and 3-fold higher affinity, respectively, for the central nervous system than for the anterior pituitary /sup 3/H-GABA binding sites. Moreover, THIP and SL 76002 have demonstrated to be respectively, 25- and 1000- fold less potent than muscimol in inhibiting /sup 3/H- GABA binding at the level of the anterior pituitary and about 25- and 2700-fold less potent at the level of the medio-basal hypothalamus. Under basal conditions, either THIP or SL 76002 were ineffective to reduce prolactin release. However, after stimulation of prolactin secretion through blockade of the dopaminergic neurotransmission with haloperidol (0.1 mg/kg), both THIP (10 mg/kg) and SL 76002 (200 mg/kg) significantly counteracted the neuroleptic-induced prolactin rise with a potency which is in line with their ability to inhibit /sup 3/H-GABA binding in the anterior pituitary. The present results indicate that both compounds inhibit prolactin release under specific experimental situations probably through a GABAergic mechanism. In view of the endocrine effects of these GABA-mimetic compounds, the possibility arises for an application of these type of drugs in clinical neuroendocrinology. 35 references, 3 figures, 2 tables.

  4. Depolarization by K+ and glutamate activates different neurotransmitter release mechanisms in GABAergic neurons: vesicular versus non-vesicular release of GABA

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, Gert Helge; Schousboe, A


    Neurotransmitter release and changes in the concentration of intracellular free calcium ([Ca++]i) were studied in cultured GABAergic cerebral cortical neurons, from mice, upon depolarization with either an unphysiologically high potassium concentration (55 mM) or the physiological excitatory...... neurotransmitter glutamate (100 microM). Both depolarizing stimuli exerted prompt increases in the release of preloaded [3H]GABA as well as in [Ca++]i. However, the basic properties of transmitter release and the increase in [Ca++]i under a variety of conditions were different during stimulation with K...... in nature whereas that induced by the neurotransmitter glutamate is not....

  5. Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism (United States)


    AWARD NUMBER: W81XWH-13-1-0144 TITLE: Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism PRINCIPAL INVESTIGATOR...SUBTITLE 5a. CONTRACT NUMBER Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism 5b. GRANT NUMBER W81XWH-13-1-0144 5c...ABSTRACT Autism spectrum disorder (ASD) is a polygenic signaling disorder that may result, in part, from an imbalance in excitatory and inhibitory

  6. Human iPSC-Derived GABA Ergic Precursor Cell Therapy for Chronic Epilepsy (United States)


    AWARD NUMBER: W81XWH-14-1-0558 TITLE: Human iPSC-Derived GABA-Ergic Precursor Cell Therapy for Chronic Epilepsy PRINCIPAL INVESTIGATOR: Ashok K...AND SUBTITLE 5a. CONTRACT NUMBER Human iPSC-Derived GABA-Ergic Precursor Cell Therapy for Chronic Epilepsy 5b. GRANT NUMBER W81XWH-14-1-0558 5c...exhibiting chronic temporal lobe epilepsy (TLE) would: (1) greatly diminish the frequency and intensity of spontaneous recurrent seizures (SRS, Specific

  7. Thalamic GABA predicts fine motor performance in manganese-exposed smelter workers.

    Directory of Open Access Journals (Sweden)

    Zaiyang Long

    Full Text Available Overexposure to manganese (Mn may lead to parkinsonian symptoms including motor deficits. The main inhibitory neurotransmitter gamma-aminobutyric acid (GABA is known to play a pivotal role in the regulation and performance of movement. Therefore this study was aimed at testing the hypothesis that an alteration of GABA following Mn exposure may be associated with fine motor performance in occupationally exposed workers and may underlie the mechanism of Mn-induced motor deficits. A cohort of nine Mn-exposed male smelter workers from an Mn-iron alloy factory and 23 gender- and age-matched controls were recruited and underwent neurological exams, magnetic resonance spectroscopy (MRS measurements, and Purdue pegboard motor testing. Short-echo-time MRS was used to measure N-Acetyl-aspartate (NAA and myo-inositol (mI. GABA was detected with a MEGA-PRESS J-editing MRS sequence. The mean thalamic GABA level was significantly increased in smelter workers compared to controls (p = 0.009. Multiple linear regression analysis reveals (1 a significant association between the increase in GABA level and the duration of exposure (R(2 = 0.660, p = 0.039, and (2 significant inverse associations between GABA levels and all Purdue pegboard test scores (for summation of all scores R(2 = 0.902, p = 0.001 in the smelter workers. In addition, levels of mI were reduced significantly in the thalamus and PCC of smelter workers compared to controls (p = 0.030 and p = 0.009, respectively. In conclusion, our results show clear associations between thalamic GABA levels and fine motor performance. Thus in Mn-exposed subjects, increased thalamic GABA levels may serve as a biomarker for subtle deficits in motor control and may become valuable for early diagnosis of Mn poisoning.

  8. Prospective frequency correction for macromolecule-suppressed GABA editing at 3T. (United States)

    Edden, Richard A E; Oeltzschner, Georg; Harris, Ashley D; Puts, Nicolaas A J; Chan, Kimberly L; Boer, Vincent O; Schär, Michael; Barker, Peter B


    To investigate the effects of B0 field offsets and drift on macromolecule (MM)-suppressed GABA-editing experiments, and to implement and test a prospective correction scheme. "Symmetric" editing schemes are proposed to suppress unwanted coedited MM signals in GABA editing. Full density-matrix simulations of both conventional (nonsymmetric) and symmetric MM-suppressed editing schemes were performed for the GABA spin system to evaluate their offset-dependence. Phantom and in vivo (15 subjects at 3T) GABA-edited experiments with symmetrical suppression of MM signals were performed to quantify the effects of field offsets on the total GABA+MM signal (designated GABA+). A prospective frequency correction method based on interleaved water referencing (IWR) acquisitions was implemented and its experimental performance evaluated during positive and negative drift. Simulations show that the signal from MM-suppressed symmetrical editing schemes is an order of magnitude more susceptible to field offsets than the signal from nonsymmetric editing schemes. The MM-suppressed GABA signal changes by 8.6% per Hz for small field offsets. IWR significantly reduces variance in the field offset and measured GABA levels (both P editing schemes substantially increase the dependence of measurements on B0 field offsets, which can arise due to patient movement and/or scanner instability. It is recommended that symmetrical editing should be used in combination with effective B0 stabilization, such as that provided by IWR. J. Magn. Reson. Imaging 2016;44:1474-1482. © 2016 International Society for Magnetic Resonance in Medicine.

  9. A switch from GABA inhibition to excitation of vasopressin neurons exacerbates the development angiotensin II-dependent hypertension. (United States)

    Korpal, Aaron K; Han, Su Young; Schwenke, Daryl O; Brown, Colin H


    Hypothalamic magnocellular neurons secrete vasopressin into the systemic circulation to maintain blood pressure by increasing renal water reabsorption and by vasoconstriction. When blood pressure rises, baroreflex activation normally inhibits vasopressin neurons via activation of GABAergic inputs. However, plasma vasopressin levels are paradoxically elevated in several models of hypertension and in some patients with essential hypertension, despite increased blood pressure. We have previously shown that vasopressin neuron activity is increased early in the development of moderate angiotensin II-dependent hypertension via blunted baroreflex inhibition of vasopressin neurons. Here, we show that antagonism of vasopressin-induced vasoconstriction slows the development of hypertension and that local administration of a GABAA receptor antagonist inhibits vasopressin neurons during, but not before, the onset of hypertension. Taken together, our data suggest that vasopressin exacerbates the increase in blood pressure evident early in the development hypertension and that blunted baroreflex inhibition of vasopressin neurons is underpinned by an excitatory shift in their response to endogenous GABA signalling. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  10. GABA-shunt enzymes activity in GH3 cells with reduced level of PMCA2 or PMCA3 isoform

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Antoni, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Zylinska, Ludmila, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Boczek, Tomasz, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland); Rebas, Elzbieta, E-mail: [Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str., 92-215 Lodz (Poland)


    Highlights: {yields} Suppression of PMCA2 or PMCA3 slows down proliferation of GH3 cells. {yields} PMCA2 suppression lowers the activity of GABA-shunt enzymes. {yields} PMCA3 suppression increases the expression of glutamate decarboxylase 65. {yields} PMCA2 and PMCA3 function appears to be linked to regulation of GABA metabolism. -- Abstract: GABA ({gamma}-aminobutyric acid) is important neurotransmitter and regulator of endocrine functions. Its metabolism involves three enzymes: glutamate decarboxylase (GAD65 and GAD67), GABA aminotransferase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH). As many cellular processes GABA turnover can depend on calcium homeostasis, which is maintained by plasma membrane calcium ATPases (PMCAs). In excitable cells PMCA2 and PMCA3 isoforms are particularly important. In this study we focused on GABA-metabolizing enzymes expression and activity in rat anterior pituitary GH3 cells with suppressed expression of PMCA2 or PMCA3. We observed that PMCA3-reduced cells have increased GAD65 expression. Suppression of PMCA2 caused a decrease in total GAD and GABA-T activity. These results indicate that PMCA2 and PMCA3 presence may be an important regulatory factor in GABA metabolism. Results suggest that PMCA2 and PMCA3 function is rather related to regulation of GABA synthesis and degradation than supplying cells with metabolites, which can be potentially energetic source.

  11. Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice. (United States)

    Liu, Xinhuai; Porteous, Robert; Herbison, Allan E


    Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABA A and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABA A -mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.

  12. In vivo quantification of intracerebral GABA by single-voxel {sup 1}H-MRS-How reproducible are the results?

    Energy Technology Data Exchange (ETDEWEB)

    Bogner, W. [MR Centre of Excellence, Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)], E-mail:; Gruber, S. [MR Centre of Excellence, Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)], E-mail:; Doelken, M. [Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Austria)], E-mail:; Stadlbauer, A. [Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Austria)], E-mail:; Ganslandt, O. [Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Austria)], E-mail:; Boettcher, U. [Siemens Medical Solution, Karl-Schall Str. 6, D-91052 Erlangen (Germany)], E-mail:; Trattnig, S. [MR Centre of Excellence, Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)], E-mail:; Doerfler, A. [Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Austria)], E-mail:; Stefan, H. [Center Epilepsy Erlangen (ZEE), Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Germany)], E-mail:; Hammen, T. [Center Epilepsy Erlangen (ZEE), Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen (Germany)], E-mail:


    Gamma aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the human brain. It plays a decisive role in a variety of nervous system disorders, such as anxiety disorders, epilepsy, schizophrenia, insomnia, and many others. The reproducibility of GABA quantification results obtained with a single-voxel spectroscopy J-difference editing sequence with Point Resolved Spectroscopy localization (MEGA-PRESS) was determined on a 3.0 Tesla MR scanner in healthy adults. Eleven volunteers were measured in long- and short-term intervals. Intra- and inter-subject reproducibility were evaluated. Internal referencing of GABA+ to total creatine (tCr) and water (H{sub 2}O), as well as two different post-processing methods for the evaluation (signal integration and time-domain fitting) were compared. In all subjects lower coefficient of variation and therefore higher reproducibility can be observed for fitting compared to integration. The GABA+/tCr ratio performs better than the GABA+/H{sub 2}O ratio or GABA+ without internal referencing for both fitting and integration (GABA+/tCr: 13.3% and 17.0%; GABA+/H{sub 2}O: 15.0% and 17.8%; GABA+: 19.2% and 21.7%). Four-day measurements on three subjects showed higher intra- than inter-subject reproducibility (GABA+/tCr {approx}10-12%). With a coefficient of variation of about 13% for inter-subject and 10-12% for intra-subject variability of GABA+/tCr, this technique seems to be a precise tool that can detect GABA confidently. The results of this study show the reproducibility limitations of GABA quantification in vivo, which are necessary for further clinical studies.

  13. Efficient increase of ɣ-aminobutyric acid (GABA) content in tomato fruits by targeted mutagenesis. (United States)

    Nonaka, Satoko; Arai, Chikako; Takayama, Mariko; Matsukura, Chiaki; Ezura, Hiroshi


    γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid that has hypotensive effects. Tomato (Solanum lycopersicum L.) is among the most widely cultivated and consumed vegetables in the world and contains higher levels of GABA than other major crops. Increasing these levels can further enhance the blood pressure-lowering function of tomato fruit. Glutamate decarboxylase (GAD) is a key enzyme in GABA biosynthesis; it has a C-terminal autoinhibitory domain that regulates enzymatic function, and deleting this domain increases GAD activity. The tomato genome has five GAD genes (SlGAD1-5), of which two (SlGAD2 and SlGAD3) are expressed during tomato fruit development. To increase GABA content in tomato, we deleted the autoinhibitory domain of SlGAD2 and SlGAD3 using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas)9 technology. Introducing a stop codon immediately before the autoinhibitory domain increased GABA accumulation by 7 to 15 fold while having variable effects on plant and fruit size and yield. This is the first study describing the application of the CRISPR/Cas9 system to increase GABA content in tomato fruits. Our findings provide a basis for the improvement of other types of crop by CRISPR/Cas9-based genetic modification.

  14. Inhibition of Activity of GABA Transporter GAT1 by δ-Opioid Receptor

    Directory of Open Access Journals (Sweden)

    Lu Pu


    Full Text Available Analgesia is a well-documented effect of acupuncture. A critical role in pain sensation plays the nervous system, including the GABAergic system and opioid receptor (OR activation. Here we investigated regulation of GABA transporter GAT1 by δOR in rats and in Xenopus oocytes. Synaptosomes of brain from rats chronically exposed to opiates exhibited reduced GABA uptake, indicating that GABA transport might be regulated by opioid receptors. For further investigation we have expressed GAT1 of mouse brain together with mouse δOR and μOR in Xenopus oocytes. The function of GAT1 was analyzed in terms of Na+-dependent [3H]GABA uptake as well as GAT1-mediated currents. Coexpression of δOR led to reduced number of fully functional GAT1 transporters, reduced substrate translocation, and GAT1-mediated current. Activation of δOR further reduced the rate of GABA uptake as well as GAT1-mediated current. Coexpression of μOR, as well as μOR activation, affected neither the number of transporters, nor rate of GABA uptake, nor GAT1-mediated current. Inhibition of GAT1-mediated current by activation of δOR was confirmed in whole-cell patch-clamp experiments on rat brain slices of periaqueductal gray. We conclude that inhibition of GAT1 function will strengthen the inhibitory action of the GABAergic system and hence may contribute to acupuncture-induced analgesia.

  15. Intestinal Microbiota-Derived GABA Mediates Interleukin-17 Expression during EnterotoxigenicEscherichia coliInfection. (United States)

    Ren, Wenkai; Yin, Jie; Xiao, Hao; Chen, Shuai; Liu, Gang; Tan, Bie; Li, Nengzhang; Peng, Yuanyi; Li, Tiejun; Zeng, Benhua; Li, Wenxia; Wei, Hong; Yin, Zhinan; Wu, Guoyao; Hardwidge, Philip R; Yin, Yulong


    Intestinal microbiota has critical importance in pathogenesis of intestinal infection; however, the role of intestinal microbiota in intestinal immunity during enterotoxigenic Escherichia coli (ETEC) infection is poorly understood. The present study tested the hypothesis that the intestinal microbiota is associated with intestinal interleukin-17 (IL-17) expression in response to ETEC infection. Here, we found ETEC infection induced expression of intestinal IL-17 and dysbiosis of intestinal microbiota, increasing abundance of γ-aminobutyric acid (GABA)-producing Lactococcus lactis subsp. lactis . Antibiotics treatment in mice lowered the expression of intestinal IL-17 during ETEC infection, while GABA or L. lactis subsp. lactis administration restored the expression of intestinal IL-17. L. lactis subsp. lactis administration also promoted expression of intestinal IL-17 in germ-free mice during ETEC infection. GABA enhanced intestinal IL-17 expression in the context of ETEC infection through activating mechanistic target of rapamycin complex 1 (mTORC1)-ribosomal protein S6 kinase 1 (S6K1) signaling. GABA-mTORC1 signaling also affected intestinal IL-17 expression in response to Citrobacter rodentium infection and in drug-induced model of intestinal inflammation. These findings highlight the importance of intestinal GABA signaling in intestinal IL-17 expression during intestinal infection and indicate the potential of intestinal microbiota-GABA signaling in IL-17-associated intestinal diseases.

  16. Furosemide action on cerebellar GABA(A) receptors in alcohol-sensitive ANT rats. (United States)

    Mäkelä, R; Uusi-Oukari, M; Oja, S S; Alho, H; Anghelescu, I; Klawe, C; Lüddens, H; Korpi, E R


    Furosemide increases the basal tert-[35S]butylbicyclophosphorothionate ([35S]TBPS) binding and reverses the inhibition of the binding by gamma-aminobutyric acid (GABA) in the cerebellar GABA(A) receptors containing the alpha6 and beta2/beta3 subunits. These effects are less pronounced in the alcohol-sensitive (ANT) than in the alcohol-insensitive (AT) rat line. The difference between the rat lines in the increase of basal [35S]TBPS binding was removed after a longer preincubation with ethylendiaminetetraacetic acid (EDTA) containing buffer, but long preincubation did not reduce the GABA content of the incubation fluid or remove the difference in GABA antagonism by furosemide. The GABA sensitivity of the [35S]TBPS binding did not differ between the rat lines. There was no nucleotide sequence difference in the beta2 or beta3 subunits between the rat lines and similar beta2/3 subunit-dependent agonistic actions by methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) in the rat lines were detected. The data suggest that there are still unknown structural alterations in the cerebellar GABA(A) receptors between the AT and ANT rat lines, possibly associated with differential alcohol sensitivity.

  17. Multiple Forms of Endocannabinoid and Endovanilloid Signaling Regulate the Tonic Control of GABA Release (United States)

    Lee, Sang-Hun; Ledri, Marco; Tóth, Blanka; Marchionni, Ivan; Henstridge, Christopher M.; Dudok, Barna; Kenesei, Kata; Barna, László; Szabó, Szilárd I.; Renkecz, Tibor; Oberoi, Michelle; Watanabe, Masahiko; Limoli, Charles L.; Horvai, George; Soltesz, Ivan


    Persistent CB1 cannabinoid receptor activity limits neurotransmitter release at various synapses throughout the brain. However, it is not fully understood how constitutively active CB1 receptors, tonic endocannabinoid signaling, and its regulation by multiple serine hydrolases contribute to the synapse-specific calibration of neurotransmitter release probability. To address this question at perisomatic and dendritic GABAergic synapses in the mouse hippocampus, we used a combination of paired whole-cell patch-clamp recording, liquid chromatography/tandem mass spectrometry, stochastic optical reconstruction microscopy super-resolution imaging, and immunogold electron microscopy. Unexpectedly, application of the CB1 antagonist and inverse agonist AM251 [N-1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide], but not the neutral antagonist NESS0327 [8-chloro-1-(2,4-dichlorophenyl)-N-piperidin-1-yl-5,6-dihydro-4H-benzo[2,3]cyclohepta[2,4-b]pyrazole-3-carboxamine], significantly increased synaptic transmission between CB1-positive perisomatic interneurons and CA1 pyramidal neurons. JZL184 (4-nitrophenyl 4-[bis(1,3-benzodioxol-5-yl)(hydroxy)methyl]piperidine-1-carboxylate), a selective inhibitor of monoacylglycerol lipase (MGL), the presynaptic degrading enzyme of the endocannabinoid 2-arachidonoylglycerol (2-AG), elicited a robust increase in 2-AG levels and concomitantly decreased GABAergic transmission. In contrast, inhibition of fatty acid amide hydrolase (FAAH) by PF3845 (N-pyridin-3-yl-4-[[3-[5-(trifluoromethyl)pyridin-2-yl]oxyphenyl]methyl]piperidine-1-carboxamide) elevated endocannabinoid/endovanilloid anandamide levels but did not change GABAergic synaptic activity. However, FAAH inhibitors attenuated tonic 2-AG increase and also decreased its synaptic effects. This antagonistic interaction required the activation of the transient receptor potential vanilloid receptor TRPV1, which was concentrated on postsynaptic

  18. Dynamic changes in extracellular release of GABA and glutamate in the lateral septum during social play behavior in juvenile rats: Implications for sex-specific regulation of social play behavior (United States)

    Bredewold, Remco; Schiavo, Jennifer K.; van der Hart, Marieke; Verreij, Michelle; Veenema, Alexa H.


    Social play is a motivated and rewarding behavior that is displayed by nearly all mammals and peaks in the juvenile period. Moreover, social play is essential for the development of social skills and is impaired in social disorders like autism. We recently showed that the lateral septum (LS) is involved in the regulation of social play behavior in juvenile male and female rats. The LS is largely modulated by GABA and glutamate neurotransmission, but their role in social play behavior is unknown. Here, we determined whether social play behavior is associated with changes in the extracellular release of GABA and glutamate in the LS and to what extent such changes modulate social play behavior in male and female juvenile rats. Using intracerebral microdialysis in freely behaving rats, we found no sex difference in extracellular GABA concentrations, but extracellular glutamate concentrations are higher in males than in females under baseline condition and during social play. This resulted in a higher glutamate/GABA concentration ratio in males versus females and thus, an excitatory predominance in the LS of males. Furthermore, social play behavior in both sexes is associated with significant increases in extracellular release of GABA and glutamate in the LS. Pharmacological blockade of GABA-A receptors in the LS with bicuculline (100 ng/0.5 µl, 250 ng/0.5 µl) dose-dependently decreased the duration of social play behavior in both sexes. In contrast, pharmacological blockade of ionotropic glutamate receptors (NMDA and AMPA/kainate receptors) in the LS with AP-5 + CNQX (2 mM+0.4 mM/0.5 µl, 30 mM+3 mM/0.5 µl) dose-dependently decreased the duration of social play behavior in females, but did not alter social play behavior in males. Together, these data suggest a role for GABA neurotransmission in the LS in the regulation of juvenile social play behavior in both sexes, while glutamate neurotransmission in the LS is involved in the sex-specific regulation of juvenile

  19. GABA(A) receptor modulation by terpenoids from Sideritis extracts. (United States)

    Kessler, Artur; Sahin-Nadeem, Hilal; Lummis, Sarah C R; Weigel, Ingrid; Pischetsrieder, Monika; Buettner, Andrea; Villmann, Carmen


    GABAA receptors are modulated by Sideritis extracts. The aim of this study was to identify single substances from Sideritis extracts responsible for GABAA receptor modulation. Single volatile substances identified by GC have been tested in two expression systems, Xenopus oocytes and human embryonic kidney cells. Some of these substances, especially carvacrol, were highly potent on GABAA receptors composed of α1β2 and α1β2γ2 subunits. All effects measured were independent from the presence of the γ2 subunit. As Sideritis extracts contain a high amount of terpenes, 13 terpenes with similar structure elements were tested in the same way. Following a prescreening on α1β2 GABAA receptors, a high-throughput method was used for identification of the most effective terpenoid substances on GABA-affinity of α1β2γ2 receptors expressed in transfected cell lines. Isopulegol, pinocarveol, verbenol, and myrtenol were the most potent modifiers of GABAA receptor function. Comparing the chemical structures, the action of terpenes on GABAA receptors is most probably due to the presence of hydroxyl groups and a bicyclic character of the substances tested. We propose an allosteric modulation independent from the γ2 subunit and similar to the action of alcohols and anesthetics. © 2013 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim.

  20. Endogenous Peer Effects: Fact or Fiction? (United States)

    Yeung, Ryan; Nguyen-Hoang, Phuong


    The authors examine endogenous peer effects, which occur when a student's behavior or outcome is a function of the behavior or outcome of his or her peer group. Endogenous peer effects have important implications for educational policies such as busing, school choice and tracking. In this study, the authors quantitatively review the literature on…

  1. Effects of surface functionalization of hydrophilic NaYF4 nanocrystals doped with Eu3+ on glutamate and GABA transport in brain synaptosomes (United States)

    Sojka, Bartlomiej; Kociołek, Daria; Banski, Mateusz; Borisova, Tatiana; Pozdnyakova, Natalia; Pastukhov, Artem; Borysov, Arsenii; Dudarenko, Marina; Podhorodecki, Artur


    Specific rare earth doped nanocrystals (NCs), a recent class of nanoparticles with fluorescent features, have great bioanalytical potential. Neuroactive properties of NaYF4 nanocrystals doped with Eu3+ were assessed based on the analysis of their effects on glutamate- and γ-aminobutyric acid (GABA) transport process in nerve terminals isolated from rat brain (synaptosomes). Two types of hydrophilic NCs were examined in this work: (i) coated by polyethylene glycol (PEG) and (ii) with OH groups at the surface. It was found that NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH within the concentration range of 0.5-3.5 and 0.5-1.5 mg/ml, respectively, did not influence Na+-dependent transporter-dependent l-[14C]glutamate and [3H]GABA uptake and the ambient level of the neurotransmitters in the synaptosomes. An increase in NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH concentrations up to 7.5 and 3.5 mg/ml, respectively, led to the (1) attenuation of the initial velocity of uptake of l-[14C]glutamate and [3H]GABA and (2) elevation of ambient neurotransmitters in the suspension of nerve terminals. In the mentioned concentrations, nanocrystals did not influence acidification of synaptic vesicles that was shown with pH-sensitive fluorescent dye acridine orange, however, decreased the potential of the plasma membrane of synaptosomes. In comparison with other nanoparticles studied with similar methodological approach, NCs start to exhibit their effects on neurotransmitter transport at concentrations several times higher than those shown for carbon dots, detonation nanodiamonds and an iron storage protein ferritin, whose activity can be registered at 0.08, 0.5 and 0.08 mg/ml, respectively. Therefore, NCs can be considered lesser neurotoxic as compared to above nanoparticles.

  2. Demonstration of extensive GABA synthesis in the small population of GAD positive neurons in cerebellar cultures by the use of pharmacological tools

    DEFF Research Database (Denmark)

    Sonnewald, Ursula; Kortner, Trond M; Qu, Hong


    Cultures of dissociated cerebella from 7-day-old mice were maintained in vitro for 1-13 days. GABA biosynthesis and degradation were studied during development in culture and pharmacological agents were used to identify the enzymes involved. The amount of GABA increased, whereas that of glutamate...... was unchanged during the first 5 days and both decreased thereafter. The presence of aminooxyacetic acid (AOAA, 10 microM) which inhibits transaminases and other pyridoxal phosphate dependent enzymes including GABA-transaminase (GABA-T), in the culture medium caused an increase in the intracellular amount...... of GABA and a decrease in glutamate. The GABA content was also increased following exposure to the specific GABA-T inhibitor gamma-vinyl GABA. From day 6 in culture (day 4 when cultured in the presence of AOAA) GABA levels in the medium were increased compared to that in medium from 1-day-old cultures...

  3. GABA agonist induced changes in ultrastructure and GABA receptor expression in cerebellar granule cells is linked to hyperpolarization of the neurons

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, Gert Helge; Schousboe, A


    treatment did not lead to formation of low affinity GABA receptors. Studies of the ultrastructure of the cells (4-day-old cultures) showed that exposure to bromide or valinomycin mimicked the ability of THIP to enhance the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles...

  4. Harmful impact on presynaptic glutamate and GABA transport by carbon dots synthesized from sulfur-containing carbohydrate precursor. (United States)

    Borisova, Tatiana; Dekaliuk, Mariia; Pozdnyakova, Natalia; Pastukhov, Artem; Dudarenko, Marina; Borysov, Arsenii; Vari, Sandor G; Demchenko, Alexander P


    Carbon nanoparticles that may be potent air pollutants with adverse effects on human health often contain heteroatoms including sulfur. In order to study in detail their effects on different physiological and biochemical processes, artificially produced carbon dots (CDs) with well-controlled composition that allows fluorescence detection may be of great use. Having been prepared from different types of organic precursors, CDs expose different atoms at their surface suggesting a broad variation of functional groups. Recently, we demonstrated neurotoxic properties of CDs synthesized from the amino acid β-alanine, and it is of importance to analyze whether CDs obtained from different precursors and particularly those exposing sulfur atoms induce similar neurotoxic effects. This study focused on synthesis of CDs from the sulfur-containing precursor thiourea-CDs (TU-CDs) with a size less than 10 nm, their characterization, and neuroactivity assessment. Neuroactive properties of TU-CDs were analyzed based on their effects on the key characteristics of glutamatergic and γ-aminobutyric acid (GABA) neurotransmission in isolated rat brain nerve terminals. It was observed that TU-CDs (0.5-1.0 mg/ml) attenuated the initial velocity of Na + -dependent transporter-mediated uptake and accumulation of L-[ 14 C]glutamate and [ 3 H]GABA by nerve terminals in a dose-dependent manner and increased the ambient level of the neurotransmitters. Starting from the concentration of 0.2 mg/ml, TU-CDs evoked a gradual dose-dependent depolarization of the plasma membrane of nerve terminals measured with the cationic potentiometric dye rhodamine 6G. Within the concentration range of 0.1-0.5 mg/ml, TU-CDs caused an "unphysiological" step-like increase in fluorescence intensity of the рН-sensitive fluorescent dye acridine orange accumulated by synaptic vesicles. Therefore, despite different surface properties and fluorescent features of CDs prepared from different starting materials

  5. Approaches towards endogenous pancreatic regeneration. (United States)

    Banerjee, Meenal; Kanitkar, Meghana; Bhonde, Ramesh R


    The phenomenon of pancreatic regeneration in mammals has been well documented. It has been shown that pancreatic tissue is able to regenerate in several species of mammal after surgical insult. This tissue is also known to have the potential to maintain or increase its beta-cell mass in response to metabolic demands during pregnancy and obesity. Since deficiency in beta-cell mass is the hallmark of most forms of diabetes, it is worthwhile understanding pancreatic regeneration in the context of this disease. With this view in mind, this article aims to discuss the potential use in clinical strategies of knowledge that we obtained from studies carried out in animal models of diabetes. Approaches to achieve this goal involve the use of biomolecules, adult stem cells and gene therapy. Various molecules, such as glucagon-like peptide-1, beta-cellulin, nicotinamide, gastrin, epidermal growth factor-1 and thyroid hormone, play major roles in the initiation of endogenous islet regeneration in diabetes. The most accepted hypothesis is that these molecules stimulate islet precursor cells to undergo neogenesis or to induce replication of existing beta-cells, emphasizing the importance of pancreas-resident stem/progenitor cells in islet regeneration. Moreover, the potential of adult stem cell population from bone marrow, umbilical cord blood, liver, spleen, or amniotic membrane, is also discussed with regard to their potential to induce pancreatic regeneration.

  6. GABA production and structure of gadB/gadC genes in Lactobacillus and Bifidobacterium strains from human microbiota. (United States)

    Yunes, R A; Poluektova, E U; Dyachkova, M S; Klimina, K M; Kovtun, A S; Averina, O V; Orlova, V S; Danilenko, V N


    Gamma-amino butyric acid (GABA) is an active biogenic substance synthesized in plants, fungi, vertebrate animals and bacteria. Lactic acid bacteria are considered the main producers of GABA among bacteria. GABA-producing lactobacilli are isolated from food products such as cheese, yogurt, sourdough, etc. and are the source of bioactive properties assigned to those foods. The ability of human-derived lactobacilli and bifidobacteria to synthesize GABA remains poorly characterized. In this paper, we screened our collection of 135 human-derived Lactobacillus and Bifidobacterium strains for their ability to produce GABA from its precursor monosodium glutamate. Fifty eight strains were able to produce GABA. The most efficient GABA-producers were Bifidobacterium strains (up to 6 g/L). Time profiles of cell growth and GABA production as well as the influence of pyridoxal phosphate on GABA production were studied for L. plantarum 90sk, L. brevis 15f, B. adolescentis 150 and B. angulatum GT102. DNA of these strains was sequenced; the gadB and gadC genes were identified. The presence of these genes was analyzed in 14 metagenomes of healthy individuals. The genes were found in the following genera of bacteria: Bacteroidetes (Bacteroides, Parabacteroides, Alistipes, Odoribacter, Prevotella), Proteobacterium (Esherichia), Firmicutes (Enterococcus), Actinobacteria (Bifidobacterium). These data indicate that gad genes as well as the ability to produce GABA are widely distributed among lactobacilli and bifidobacteria (mainly in L. plantarum, L. brevis, B. adolescentis, B. angulatum, B. dentium) and other gut-derived bacterial species. Perhaps, GABA is involved in the interaction of gut microbiota with the macroorganism and the ability to synthesize GABA may be an important feature in the selection of bacterial strains - psychobiotics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Technological and safety properties of newly isolated GABA-producing Lactobacillus futsaii strains. (United States)

    Sanchart, C; Rattanaporn, O; Haltrich, D; Phukpattaranont, P; Maneerat, S


    To evaluate the technological and safety properties of Lactobacillus futsaii CS3 and CS5 isolated from Thai fermented shrimp products (Kung-Som) in order to develop a valuable gamma-aminobutyric acid (GABA)-producing starter culture. Both strains showed a high GABA-producing ability (>8 mg ml(-1) ) in MRS broth containing 20 mg ml(-1) monosodium glutamate (MSG) for 120 h. They also exhibited inhibitory activity against foodborne pathogens and spoilage bacteria. Cell surface hydrophobicity and proteolytic activity were observed in both strains. Strain CS3 survived better under simulated gastrointestinal tract conditions with only 1·5 log-units cell decrease over 8 h. Both strains showed the ability to deconjugate taurocholate and taurodeoxycholate acid. Neither virulence genes nor biogenic amine production was detected. Strain CS3 exhibited susceptibility to all tested antibiotics with the exception of vancomycin, while strain CS5 showed resistance to vancomycin, ampicillin and chloramphenicol. Based on the results obtained, Lact. futsaii CS3 is very promising as a GABA-producing and potentially probiotic starter culture strain for applications in functional fermented foods. This study focuses on the technological and safety characteristics of Lact. futsaii CS3 and CS5 including their high GABA-producing capacity for the first time. This provides a way of replacing chemical GABA by natural GABA using a GABA-producing starter culture candidate, at the same time offering the consumer new attractive food products. © 2016 The Society for Applied Microbiology.

  8. VTA GABA neurons modulate specific learning behaviours through the control of dopamine and cholinergic systems

    Directory of Open Access Journals (Sweden)

    Meaghan C Creed


    Full Text Available The mesolimbic reward system is primarily comprised of the ventral tegmental area (VTA and the nucleus accumbens (NAc as well as their afferent and efferent connections. This circuitry is essential for learning about stimuli associated with motivationally-relevant outcomes. Moreover, addictive drugs affect and remodel this system, which may underlie their addictive properties. In addition to DA neurons, the VTA also contains approximately 30% ɣ-aminobutyric acid (GABA neurons. The task of signalling both rewarding and aversive events from the VTA to the NAc has mostly been ascribed to DA neurons and the role of GABA neurons has been largely neglected until recently. GABA neurons provide local inhibition of DA neurons and also long-range inhibition of projection regions, including the NAc. Here we review studies using a combination of in vivo and ex vivo electrophysiology, pharmacogenetic and optogenetic manipulations that have characterized the functional neuroanatomy of inhibitory circuits in the mesolimbic system, and describe how GABA neurons of the VTA regulate reward and aversion-related learning. We also discuss pharmacogenetic manipulation of this system with benzodiazepines (BDZs, a class of addictive drugs, which act directly on GABAA receptors located on GABA neurons of the VTA. The results gathered with each of these approaches suggest that VTA GABA neurons bi-directionally modulate activity of local DA neurons, underlying reward or aversion at the behavioural level. Conversely, long-range GABA projections from the VTA to the NAc selectively target cholinergic interneurons (CINs to pause their firing and temporarily reduce cholinergic tone in the NAc, which modulates associative learning. Further characterization of inhibitory circuit function within and beyond the VTA is needed in order to fully understand the function of the mesolimbic system under normal and pathological conditions.

  9. GABA and glutamate levels in occlusal splint-wearing males with possible bruxism. (United States)

    Dharmadhikari, Shalmali; Romito, Laura M; Dzemidzic, Mario; Dydak, Ulrike; Xu, Jun; Bodkin, Cynthia L; Manchanda, Shalini; Byrd, Kenneth E


    The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the pathophysiology of anxiety behavioural disorders such as panic disorder and post-traumatic stress disorder and is also implicated in the manifestation of tooth-grinding and clenching behaviours generally known as bruxism. In order to test whether the stress-related behaviours of tooth-grinding and clenching share similar underlying mechanisms involving GABA and other metabolites as do anxiety-related behavioural disorders, we performed a Magnetic Resonance Spectroscopy (MRS) study for accurate, in vivo metabolite quantification in anxiety-related brain regions. MRS was performed in the right hippocampus and right thalamus involved in the hypothalamic-pituitary-adrenal axis system, together with a motor planning region (dorsal anterior cingulate cortex/pre-supplementary motor area) and right dorsolateral prefrontal cortex (DLPFC). Eight occlusal splint-wearing men (OCS) with possible tooth-grinding and clenching behaviours and nine male controls (CON) with no such behaviour were studied. Repeated-measures ANOVA showed significant Group×Region interaction for GABA+ (p = 0.001) and glutamate (Glu) (p = 0.031). Between-group post hoc ANOVA showed significantly lower levels of GABA+ (p = 0.003) and higher levels of Glu (p = 0.002) in DLPFC of OCS subjects. These GABA+ and Glu group differences remained significant (GABA+, p = 0.049; Glu, p = 0.039) after the inclusion of anxiety as a covariate. Additionally, GABA and Glu levels in the DLPFC of all subjects were negatively related (Pearson's r = -0.75, p = 0.003). These findings indicate that the oral behaviours of tooth-grinding and clenching, generally known as bruxism, may be associated with disturbances in brain GABAergic and glutamatergic systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Functional role of ambient GABA in refining neuronal circuits early in postnatal development

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    Giada eCellot


    Full Text Available Early in development, gamma-aminobutyric acid (GABA, the primary inhibitory neurotransmitter in the mature brain, depolarizes and excites targeted neurons by an outwardly directed flux of chloride, resulting from the peculiar balance between the cation-chloride importer NKCC1 and the extruder KCC2. The low expression of KCC2 at birth leads to accumulation of chloride inside the cell and to the equilibrium potential for chloride positive respect to the resting membrane potential. GABA exerts its action via synaptic and extrasynaptic GABAA receptors mediating phasic and tonic inhibition, respectively. Here, recent data on the contribution of "ambient" GABA to the refinement of neuronal circuits in the immature brain have been reviewed. In particular, we focus on the hippocampus, where, prior to the formation of conventional synapses, GABA released from growth cones and astrocytes in a calcium- and SNARE-independent way, diffuses away to activate in a paracrine fashion extrasynaptic receptors localized on distal neurons. The transient increase in intracellular calcium following the depolarizing action of GABA leads to inhibition of DNA synthesis and cell proliferation. Tonic GABA exerts also a chemotropic action on cell migration. Later on, when synapses are formed, GABA spilled out from neighboring synapses, acting mainly on extrasynaptic5, 2, 3 and  containing GABAA receptor subunits, provides the membrane depolarization necessary for principal cells to reach the window where intrinsic bursts are generated. These are instrumental in triggering calcium transients associated with network-driven GDPs which act as coincident detector signals to enhance synaptic efficacy at emerging GABAergic and glutamatergic synapses.

  11. Responses of endogenous proline in rice seedlings under chromium exposure

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    X.Z. Yu


    Full Text Available Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI or chromium nitrate chromium (III. Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues of rice seedlings exposed to chromium (III than those in chromium (VI, majority being in roots rather than shoots. Results also showed that the accumulation capacity of chromium by rice seedlings was positively correlated to chromium concentrations supplied in both chromium variants and the accumulation curve depicted an exponential trend in both chromium treatments over the entire period of exposure. Proline assays showed that both chromium variants induced the change of endogenous proline in shoots and roots of rice seedlings. Chromium (VI of 12.8 mg/L increased proline content significantly (p

  12. Methamphetamine-evoked depression of GABAB receptor signaling in GABA neurons of the VTA (United States)

    Padgett, CL; Lalive, AL; Tan, KR; Terunuma, M; Munoz, MB; Pangalos, MN; Martínez-Hernández, J; Watanabe, M; Moss, SJ; Luján, R; Lüscher, C; Slesinger, PA


    Psychostimulants induce neuroadaptations in excitatory and fast inhibitory transmission in the ventral tegmental area (VTA). Mechanisms underlying drug-evoked synaptic plasticity of slow inhibitory transmission mediated by GABAB receptors and G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels, however, are poorly understood. Here, we show that one day after methamphetamine (METH) or cocaine exposure, both synaptically-evoked and baclofen-activated GABABR-GIRK currents were significantly depressed in VTA GABA neurons, and remained depressed for 7 days. Presynaptic inhibition mediated by GABABRs on GABA terminals was also weakened. Quantitative immunoelectron microscopy revealed internalization of GABAB1R and GIRK2, which occurred coincident with dephosphorylation of Ser783 in GABAB2R, a site implicated in regulating GABABR surface expression. Inhibition of protein phosphatases recovered GABABR-GIRK currents in VTA GABA neurons of METH-injected mice. This psychostimulant-evoked impairment in GABABR signaling removes an intrinsic brake on GABA neuron spiking, which may augment GABA transmission in the mesocorticolimbic system. PMID:22405207

  13. Recent advances in γ-aminobutyric acid (GABA) properties in pulses: an overview. (United States)

    Nikmaram, Nooshin; Dar, B N; Roohinejad, Shahin; Koubaa, Mohamed; Barba, Francisco J; Greiner, Ralf; Johnson, Stuart K


    Beans, peas, and lentils are all types of pulses that are extensively used as foods around the world due to their beneficial effects on human health including their low glycaemic index, cholesterol lowering effects, ability to decrease the risk of heart diseases and their protective effects against some cancers. These health benefits are a result of their components such as bioactive proteins, dietary fibre, slowly digested starches, minerals and vitamins, and bioactive compounds. Among these bioactive compounds, γ-aminobutyric acid (GABA), a non-proteinogenic amino acid with numerous reported health benefits (e.g. anti-diabetic and hypotensive effects, depression and anxiety reduction) is of particular interest. GABA is primarily synthesised in plant tissues by the decarboxylation of l-glutamic acid in the presence of glutamate decarboxylase (GAD). It is widely reported that during various processes including enzymatic treatment, gaseous treatment (e.g. with carbon dioxide), and fermentation (with lactic acid bacteria), GABA content increases in the plant matrix. The objective of this review paper is to highlight the current state of knowledge on the occurrence of GABA in pulses with special focus on mechanisms by which GABA levels are increased and the analytical extraction and estimation methods for this bioactive phytochemical. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  14. Ventilatory effects of negative GABA(A) modulators in rhesus monkeys. (United States)

    Gerak, L R; Estupinan, L E; France, C P


    This study examined changes in ventilation produced by negative gamma-aminobutyric acid(A) (GABA(A)) modulators in rhesus monkeys. The effects of Ro 15-4513, beta-CCE and beta-CCM were examined in four rhesus monkeys breathing air or 5% CO2 in air. When monkeys breathed CO2, minute volume (VE) and frequency (f) increased, on average, to 158 and 140% of control (air), respectively. Ro 15-4513 did not modify ventilation in monkeys breathing either gas mixture; however, beta-CCE and beta-CCM increased VE and f in monkeys breathing air to between 123 and 141% of control and had no effect on ventilation of 5% CO2. Increased ventilation produced by the negative GABA(A) modulators appeared to be maximal, because ventilation was not further enhanced when the dose was increased three-fold. Each of the three negative GABA(A) modulators reversed the decreases in ventilation produced by diazepam, suggesting that these drugs are acting at benzodiazepine receptors; however, the increased ventilation produced by beta-CCE and beta-CCM might suggest that they have more negative efficacy than Ro 15-4513. These data extend previous findings by showing that some negative GABA(A) modulators (Ro 15-4513) do not alter ventilation and further indicate that changes in ventilation can be used to evaluate efficacy differences among GABA(A) modulators.

  15. Properties of Kimchi Fermented with GABA-Producing Lactic Acid Bacteria as a Starter. (United States)

    Lee, Kang Wook; Shim, Jae Min; Yao, Zhuang; Kim, Jeong A; Kim, Jeong Hwan


    Kimchi was prepared with a starter, Lactobacillus zymae GU240 producing γ-aminobutyric acid (GABA), and one precursor of GABA (glutamic acid, glutamic acid mono sodium salt (MSG), or kelp extract). L. zymae GU240, an isolate from kimchi, can grow at 7% NaCl and low temperature. Five different kimchi samples were fermented for 20 weeks at -1°C. Kimchi with starter alone could not produce GABA. GABA content was highest in kimchi with co-inoculation of starter and MSG (1%, w/w). Kimchi co-inoculated with a starter and kelp extract powder (3%, w/w) had the second highest GABA content. Addition of glutamic acid powder (1%, w/w) caused a reduction in the pH level of kimchi and growth inhibition of lactic acid bacteria (LAB) and yeasts. Kimchi samples with MSG or kelp extract showed improvement of sensory evaluation scores. The results demonstrate the possibility to produce kimchi with improved functionality and taste by using L. zymae GU240 as a starter along with a suitable precursor such as MSG or kelp extract.

  16. A Review of the Updated Pharmacophore for the Alpha 5 GABA(A Benzodiazepine Receptor Model

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    Terry Clayton


    Full Text Available An updated model of the GABA(A benzodiazepine receptor pharmacophore of the α5-BzR/GABA(A subtype has been constructed prompted by the synthesis of subtype selective ligands in light of the recent developments in both ligand synthesis, behavioral studies, and molecular modeling studies of the binding site itself. A number of BzR/GABA(A α5 subtype selective compounds were synthesized, notably α5-subtype selective inverse agonist PWZ-029 (1 which is active in enhancing cognition in both rodents and primates. In addition, a chiral positive allosteric modulator (PAM, SH-053-2′F-R-CH3 (2, has been shown to reverse the deleterious effects in the MAM-model of schizophrenia as well as alleviate constriction in airway smooth muscle. Presented here is an updated model of the pharmacophore for α5β2γ2 Bz/GABA(A receptors, including a rendering of PWZ-029 docked within the α5-binding pocket showing specific interactions of the molecule with the receptor. Differences in the included volume as compared to α1β2γ2, α2β2γ2, and α3β2γ2 will be illustrated for clarity. These new models enhance the ability to understand structural characteristics of ligands which act as agonists, antagonists, or inverse agonists at the Bz BS of GABA(A receptors.

  17. Investigation of brain GABA+ in primary hypothyroidism using edited proton MR spectroscopy. (United States)

    Liu, Bo; Yang, Huan; Gao, Fei; Wang, Qing; Zhao, Bin; Gong, Tao; Wang, Zhensong; Chen, Weibo; Wang, Guangbin; Edden, Richard A E


    Evidence indicates that thyroid hormones have effects on the inhibitory GABAergic system. The aim of this study was to investigate whether brain GABA levels are altered in patients with hypothyroidism compared with healthy controls. Fifteen patients with primary hypothyroidism and 15 matched healthy controls underwent single-voxel MEGA-PRESS magnetic resonance spectroscopy at 3T, to quantify GABA levels in the median prefrontal cortex (mPFC) and posterior cingulate cortex (PCC). All participants underwent thyroid function test. Neuropsychological performances were evaluated by administration of the Montreal Cognitive Assessment (MoCA) and the 21-item Beck Depression Inventory-II (BDI-II). The patients with hypothyroidism had significantly lower GABA+ levels in the mPFC compared with healthy controls (P = 0·016), whereas no significant difference (P = 0·214) was observed in the PCC. Exploratory analyses revealed that mPFC GABA+ levels were negatively correlated with the BDI-II scores in patient group (r = -0·60, P = 0·018). No correlations were found between GABA+ levels and TSH or fT3 or fT4 levels in either region (all P > 0·05). This study suggests that alteration of GABAergic neurotransmission may play an important role in the pathophysiology of primary hypothyroidism, providing intriguing neurochemical clues to understand thyroid-brain interactions. © 2016 John Wiley & Sons Ltd.

  18. Hyperalgesic effect induced by barbiturates, midazolam and ethanol: pharmacological evidence for GABA-A receptor involvement

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    M.A.K.F. Tatsuo


    Full Text Available The involvement of GABA-A receptors in the control of nociception was studied using the tail-flick test in rats. Non-hypnotic doses of the barbiturates phenobarbital (5-50 mg/kg, pentobarbital (17-33 mg/kg, and thiopental (7.5-30 mg/kg, of the benzodiazepine midazolam (10 mg/kg or of ethanol (0.4-1.6 g/kg administered by the systemic route reduced the latency for the tail-flick response, thus inducing a 'hyperalgesic' state in the animals. In contrast, non-convulsant doses of the GABA-A antagonist picrotoxin (0.12-1.0 mg/kg administered systemically induced an increase in the latency for the tail-flick response, therefore characterizing an 'antinociceptive' state. Previous picrotoxin (0.12 mg/kg treatment abolished the hyperalgesic state induced by effective doses of the barbiturates, midazolam or ethanol. Since phenobarbital, midazolam and ethanol reproduced the described hyperalgesic effect of GABA-A-specific agonists (muscimol, THIP, which is specifically antagonized by the GABA-A antagonist picrotoxin, our results suggest that GABA-A receptors are tonically involved in the modulation of nociception in the rat central nervous system

  19. GABA and glutamate immunoreactivity in tentacles of the sea anemone Phymactis papillosa (LESSON 1830). (United States)

    Delgado, Luz M; Couve, Eduardo; Schmachtenberg, Oliver


    Sea anemones have a structurally simple nervous system that controls behaviors like feeding, locomotion, aggression, and defense. Specific chemical and tactile stimuli are transduced by ectodermal sensory cells and transmitted via a neural network to cnidocytes and epithelio-muscular cells, but the nature of the neurotransmitters operating in these processes is still under discussion. Previous studies demonstrated an important role of peptidergic transmission in cnidarians, but during the last decade the contribution of conventional neurotransmitters became increasingly evident. Here, we used immunohistochemistry on light and electron microscopical preparations to investigate the localization of glutamate and GABA in tentacle cross-sections of the sea anemone Phymactis papillosa. Our results demonstrate strong glutamate immunoreactivity in the nerve plexus, while GABA labeling was most prominent in the underlying epithelio-muscular layer. Immunoreactivity for both molecules was also found in glandular epithelial cells, and putative sensory cells were GABA positive. Under electron microscopy, both glutamate and GABA immunogold labeling was found in putative neural processes within the neural plexus. These data support a function of glutamate and GABA as signaling molecules in the nervous system of sea anemones.

  20. The role of the GABA system in amphetamine-type stimulant use disorders

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    Dongliang eJiao


    Full Text Available Abuse of amphetamine-type stimulants (ATS has become a global public health problem. ATS causes severe neurotoxicity, which could lead to addiction and could induce psychotic disorders or cognitive dysfunctions. However, until now, there has been a lack of effective medicines for treating ATS-related problems. Findings from recent studies indicate that in addition to the traditional dopamine-ergic system, the GABA (gamma-aminobutyric acid-ergic system plays an important role in ATS abuse. However the exact mechanisms of the GABA-ergic system in amphetamine-type stimulant use disorders are not fully understood. This review discusses the role of the GABA-ergic system in ATS use disorders, including ATS induced psychotic disorders and cognitive dysfunctions. We conclude that the GABA-ergic system are importantly involved in the development of ATS use disorders through multiple pathways, and that therapies or medicines that target specific members of the GABA-ergic system may be novel effective interventions for the treatment of ATS use disorders.

  1. GABA/benzodiazepine receptor complex in long-sleep and short-sleep mice

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    Marley, R.J.


    LS mice are more sensitive to benzodiazepine-induced anesthesia; however, the two lines do not differ in their hypothermic response to flurazepam. SS mice are more resistant to 3-mercaptopropionic acid-induced seizures and more sensitive to the anticonvulsant effects of benzodiazepines. The various correlates of GABA and benzodiazepine actions probably are the results of different mechanisms of action and/or differential regional control. Bicuculline competition for /sup 3/H-GABA binding sites is greater in SS cerebellar tissue and /sup 3/H-flunitrazepam binding is greater in the mid-brain region of LS mice. GABA enhancement of /sup 3/H-flunitrazepma binding is greater in SS mice. Ethanol also enhances /sup 3/H-flunitrazepam binding and increases the levels of /sup 3/H-flunitrazepam binding above those observed for GABA. Using correlational techniques on data from LS and SS mice and several inbred mouse strains, it was demonstrated that a positive relationship exists between the degree of receptor coupling within the GABA receptor complex and the degree of resistance to seizures.

  2. Selective GABA transporter inhibitors tiagabine and EF1502 exhibit mechanistic differences in their ability to modulate the ataxia and anticonvulsant action of the extrasynaptic GABA(A) receptor agonist gaboxadol

    DEFF Research Database (Denmark)

    Madsen, Karsten Kirkegaard; Ebert, Bjarke; Clausen, Rasmus Prætorius


    Modulation of the extracellular levels of GABA via inhibition of the synaptic GABA transporter GAT1 by the clinically effective and selective GAT1 inhibitor tiagabine [(R)-N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]nipecotic acid; Gabitril] has proven to be an effective treatment strategy for focal...

  3. Does gamma-aminobutyric acid (GABA influence the development of chronic inflammation in rheumatoid arthritis?

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    Bridges S Louis


    Full Text Available Abstract Background Recent studies have demonstrated a role for spinal p38 MAP kinase (MAPK in the development of chronic inflammation and peripheral arthritis and a role for GABA in the inhibition of p38 MAPK mediated effects. Integrating these data suggests that GABA may play a role in downregulating mechanisms that lead to the production of proinflammatory agents such as interleukin-1, interleukin-6, and matrix metalloproteinase 3 – agents implicated in the pathogenesis of rheumatoid arthritis (RA. Genetic studies have also associated RA with members of the p38 MAPK pathway. Hypothesis We propose a hypothesis for an inefficient GABA signaling system that results in unchecked proinflammatory cytokine production via the p38 MAPK pathway. This model also supports the need for increasing research in the integration of immunology and neuroscience.

  4. Proton Magnetic Resonance Spectroscopy: Relevance of Glutamate and GABA to Neuropsychology. (United States)

    Ende, Gabriele


    Proton Magnetic Resonance Spectroscopy (MRS) has been widely used to study the healthy and diseased brain in vivo. The availability of whole body MR scanners with a field strength of 3 Tesla and above permit the quantification of many metabolites including the neurotransmitters glutamate (Glu) and γ-aminobutyric acid (GABA). The potential link between neurometabolites identified by MRS and cognition and behavior has been explored in numerous studies both in healthy subjects and in patient populations. Preliminary findings suggest direct or opposite associations between GABA or Glu with impulsivity, anxiety, and dexterity. This chapter is intended to provide an overview of basic principles of MRS and the literature reporting correlations between GABA or Glu and results of neuropsychological assessments.

  5. Benzodiazepine/GABA receptor complex during severe ethanol intoxication and withdrawal in the rat

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    Hemmingsen, R.; Braestrup, C.; Nielsen, M.; Barry, D.I. (Dept. of Psychiatry, Rigshospitalet, Copenhagen, St. Hans Mental Hospital, Roskilde, and Ferrosan Research Laboratory, Soeborg, Denmark)


    The benzodiazepine/GABA (gammaaminobutyric acid) receptor complex was investigated during severe ethanol intoxication and withdrawal in the rat. The intragastric intubation technique was used to establish physical ethanol dependence in the animals. Cerebral cortex from male Wistar rats was studied 1) after 31/2 days of severe ethanol intoxication, 2) during the ethanol withdrawal reaction and 3) in a control group. The effect of GABA-ergic activation by muscimol and THIP (4,5,6,7-tetrahydroisoxazole(5,4-c)pyridin-3-01) on /sup 3/H-diazepam binding was unchanged during ethanol intoxication and withdrawal, as was the affinity constant (Ksub(D)) and the maximal number of binding sites (Bsub(max)) for /sup 3/H-flunitrazepam. In conclusion, the benzodiazepine/GABA receptor complex is unlikely to play any causual part in physical ethanol dependence.

  6. Does liver-intestine significantly degrade circulating endogenous substance P in man?

    DEFF Research Database (Denmark)

    Henriksen, J H; Schaffalitzky de Muckadell, Ove B.; Bülow, J B


    Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P...... was determined in various vascular beds during a right-sided catheterization in 13 subjects without liver insufficiency. All subjects had normal values of circulating substance P, and no significant difference was found between systemic plasma and hepatic venous or renal venous concentrations of substance P....... The results indicate that degradation of circulating endogenous substance P in man is not confined to liver-intestine or kidney but may take place in many tissues....

  7. Dynamic modulation of an orientation preference map by GABA responsible for age-related cognitive performance. (United States)

    Miyamoto, Ai; Hasegawa, Jun; Hoshino, Osamu


    Accumulating evidence suggests that cognitive declines in old (healthy) animals could arise from depression of intracortical inhibition, for which a decreased ability to produce GABA during senescence might be responsible. By simulating a neural network model of a primary visual cortical (V1) area, we investigated whether and how a lack of GABA affects cognitive performance of the network: detection of the orientation of a visual bar-stimulus. The network was composed of pyramidal (P) cells and GABAergic interneurons such as small (S) and large (L) basket cells. Intrasynaptic GABA-release from presynaptic S or L cells contributed to reducing ongoing-spontaneous (background) neuronal activity in a different manner. Namely, the former exerted feedback (S-to-P) inhibition and reduced the frequency (firing rate) of action potentials evoked in P cells. The latter reduced the number of saliently firing P cells through lateral (L-to-P) inhibition. Non-vesicular GABA-release, presumably from glia and/or neurons, into the extracellular space reduced the both, activating extrasynaptic GABAa receptors and providing P cells with tonic inhibitory currents. By this combinatorial, spatiotemporal inhibitory mechanism, the background activity as noise was significantly reduced, compared to the stimulus-evoked activity as signal, thereby improving signal-to-noise (S/N) ratio. Interestingly, GABA-spillover from the intrasynaptic cleft into the extracellular space was effective for improving orientation selectivity (orientation bias), especially when distractors interfered with detecting the bar-stimulus. These simulation results may provide some insight into how the depression of intracortical inhibition due to a reduction in GABA content in the brain leads to age-related cognitive decline.

  8. Investigation of Gamma-aminobutyric acid (GABA A receptors genes and migraine susceptibility

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    Ciccodicola Alfredo


    Full Text Available Abstract Background Migraine is a neurological disorder characterized by recurrent attacks of severe headache, affecting around 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the number and type of genes involved is still unclear. Prior linkage studies have reported mapping of a migraine gene to chromosome Xq 24–28, a region containing a cluster of genes for GABA A receptors (GABRE, GABRA3, GABRQ, which are potential candidate genes for migraine. The GABA neurotransmitter has been implicated in migraine pathophysiology previously; however its exact role has not yet been established, although GABA receptors agonists have been the target of therapeutic developments. The aim of the present research is to investigate the role of the potential candidate genes reported on chromosome Xq 24–28 region in migraine susceptibility. In this study, we have focused on the subunit GABA A receptors type ε (GABRE and type θ (GABRQ genes and their involvement in migraine. Methods We have performed an association analysis in a large population of case-controls (275 unrelated Caucasian migraineurs versus 275 controls examining a set of 3 single nucleotide polymorphisms (SNPs in the coding region (exons 3, 5 and 9 of the GABRE gene and also the I478F coding variant of the GABRQ gene. Results Our study did not show any association between the examined SNPs in our test population (P > 0.05. Conclusion Although these particular GABA receptor genes did not show positive association, further studies are necessary to consider the role of other GABA receptor genes in migraine susceptibility.

  9. Repeated phencyclidine administration alters glutamate release and decreases GABA markers in the prefrontal cortex of rats (United States)

    Amitai, Nurith; Kuczenski, Ronald; Behrens, M. Margarita; Markou, Athina


    Repeated phencyclidine (PCP) administration induces cognitive disruptions resembling those seen in schizophrenia. Alterations in glutamate transmission and γ-aminobutyric acid (GABA) function in the prefrontal cortex (PFC) have been implicated in these PCP-induced deficits, as well as in cognitive symptoms of schizophrenia. PCP-induced cognitive deficits are reversed by chronic treatment with the atypical antipsychotic clozapine in rats. We investigated the effects of a single injection vs. repeated administration of PCP on glutamate levels in the PFC using in vivo microdialysis. Furthermore, we examined how these PCP regimens affect GABA neuronal markers in the PFC. Finally, we investigated the effects of clozapine on disruptions in glutamate levels and GABA neuronal markers induced by repeated PCP administration. Acute PCP administration (2 mg/kg) increased extracellular PFC glutamate; this increase appeared blunted, but was not eliminated, after repeated PCP pretreatment. PCP administration also strongly decreased levels of parvalbumin and glutamic acid decarboxylase-67 (two markers of GABA function) in the PFC, an effect that was maintained after a 10 day drug-free washout period and unaltered by the resumption of repeated PCP injections. All of the observed PCP effects were attenuated by chronic treatment with clozapine, an atypical antipsychotic that has partial effectiveness on cognitive impairment in schizophrenia. These findings suggest that abnormal cortical glutamate transmission, possibly driven by pathological changes in GABA function in parvalbumin-positive fast-spiking interneurons, may underlie some of the cognitive deficits in schizophrenia. A better understanding of glutamate and GABA dysregulation in schizophrenia may uncover new treatment targets for schizophrenia-related cognitive dysfunction. PMID:21238466

  10. Spinal cord GABA receptors modulate the exercise pressor reflex in decerebrate rats. (United States)

    Wang, Han-Jun; Wang, Wei; Patel, Kaushik P; Rozanski, George J; Zucker, Irving H


    Neurotransmitters and neuromodulators released by contraction-activated skeletal muscle afferents into the dorsal horn of the spinal cord initiate the central component of the exercise pressor reflex (EPR). Whether γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter within the mammalian central nervous system, is involved in the modulation of the EPR at the level of dorsal horn remains to be determined. We performed local microinjection of either the GABA(A) antagonist bicuculline or the GABA(B) antagonist CGP 52432 into the ipisilateral L4/L5 dorsal horns to investigate the effect of GABA receptor blockade on the pressor response to either static contraction induced by stimulation of the peripheral end of L4/L5 ventral roots, passive stretch, or hindlimb arterial injection of capsaicin (0.1 μg/0.2 ml) in decerebrate rats. Microinjection of either bicuculline (1 mM, 100 nl) or CGP 52432 (10 mM, 100 nl) into the L4/5 dorsal horns significantly increased the pressor and cardioaccelerator responses to all stimuli. Microinjection of either bicuculline or CGP 52432 into the L5 dorsal horn significantly increased the pressor and cardioaccelerator responses to direct microinjection of l-glutatmate (10 mM, 100 nl) into this spinal segment. The disinhibitory effect of both GABA receptor antagonists on the EPR was abolished by microinjection of the broad-spectrum glutamate receptor antagonist kynurenate (10 mM/100 nl). These data suggest that 1) GABA exerts a tonic inhibition of the EPR at the level of dorsal horn; and 2) that an interaction between glutamatergic and GABAergic inputs exist at the level of dorsal horn, contributing to spinal control of the EPR.

  11. Abnormal relationship between GABA, neurophysiology and impulsive behavior in neurofibromatosis type 1. (United States)

    Ribeiro, Maria J; Violante, Inês R; Bernardino, Inês; Edden, Richard A E; Castelo-Branco, Miguel


    Neurofibromatosis type 1 (NF1) is a neurodevelopmental disorder characterized by a broad spectrum of cognitive deficits. In particular, executive dysfunction is recognized as a core deficit of NF1, including impairments in executive attention and inhibitory control. Yet, the neural mechanisms behind these important deficits are still unknown. Here, we studied inhibitory control in a visual go/no-go task in children and adolescents with NF1 and age- and gender-matched controls (n = 16 per group). We applied a multimodal approach using high-density electroencephalography (EEG), to study the evoked brain responses, and magnetic resonance spectroscopy (MRS) to measure the levels of GABA and glutamate + glutamine in the medial frontal cortex, a brain region that plays a pivotal role in inhibitory control, and also in a control region, the occipital cortex. Finally, we run correlation analyses to identify the relationship between inhibitory control, levels of neurotransmitters, and EEG markers of neural function. Individuals with NF1 showed impaired impulse control and reduced EEG correlates of early visual processing (parieto-occipital P1) and inhibitory control (frontal P3). MRS data revealed a reduction in medial frontal GABA+/tCr (total Creatine) levels in the NF1 group, in parallel with the already reported reduced occipital GABA levels. In contrast, glutamate + glutamine/tCr levels were normal, suggesting the existence of abnormal inhibition/excitation balance in this disorder. Notably, medial frontal but not occipital GABA levels correlated with general intellectual abilities (IQ) in NF1, and inhibitory control in both groups. Surprisingly, the relationship between inhibitory control and medial frontal GABA was reversed in NF1: higher GABA was associated with a faster response style whereas in controls it was related to a cautious strategy. Abnormal GABAergic physiology appears, thus, as an important factor underlying impaired cognition in NF1, in a level and

  12. Focal Uncaging of GABA Reveals a Temporally Defined Role for GABAergic Inhibition during Appetitive Associative Olfactory Conditioning in Honeybees (United States)

    Raccuglia, Davide; Mueller, Uli


    Throughout the animal kingdom, the inhibitory neurotransmitter ?-aminobutyric acid (GABA) is a key modulator of physiological processes including learning. With respect to associative learning, the exact time in which GABA interferes with the molecular events of learning has not yet been clearly defined. To address this issue, we used two…

  13. GABA and Topiramate Inhibit the Formation of Human Macrophage-Derived Foam Cells by Modulating Cholesterol-Metabolism-Associated Molecules

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    Ying Yang


    Full Text Available Aims: γ-aminobutyric acid (GABA, the principal inhibitory neurotransmitter, acts on GABA receptors to play an important role in the modulation of macrophage functions. The present study examined the effects of GABA and a GABA receptor agonist on modulating cholesterol-metabolism-associated molecules in human monocyte-derived macrophages (HMDMs. Methods: ORO stain, HPLC, qRT-PCR, Western blot and EMSA were carried out using HMDMs exposed to ox-LDL with or without GABAergic agents as the experimental model. Results: GABA and topiramate reduced the percentage of cholesterol ester in lipid-laden HMDMs by down-regulating SR-A, CD36 and LOX-1 expression and up-regulating ABCA1, ABCG1 and SR-BI expression in lipid-laden HMDMs. The production of TNF-a was decreased in GABA-and topiramate-treated lipid-laden HMDMs, and levels of interleukin (IL-6 did not change. The activation of two signaling pathways, p38MAPK and NF-γB, was repressed by GABA and topiramate in lipid-laden HMDMs. Conclusion: GABA and topiramate inhibit the formation of human macrophage-derived foam cells and may be a possibility for macrophage targeted therapy of atherosclerotic lesions.

  14. Genome Sequence of Lactococcus lactis subsp. lactis NCDO 2118, a GABA-Producing Strain

    DEFF Research Database (Denmark)

    Oliveira, Letícia C; Saraiva, Tessália D L; Soares, Siomar C


    Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity.......Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity....

  15. Bioassay-guided isolation of apigenin with GABA-benzodiazepine activity from Tanacetum parthenium. (United States)

    Jäger, A K; Krydsfeldt, K; Rasmussen, H B


    Extracts of Tanacetum parthenium are used in the prophylactic treatment of migraine and have also been used in Danish folk medicine for the treatment of epilepsy. An ethanol extract of T. parthenium showed high affinity for the GABA(A)-benzodiazepine site. An ethanol extract of T. parthenium was fractionated by VLC on silica and preparative C18 HPLC. Each step was monitored with the GABA(A)-benzodiazepine bioassay. The fractionation led to the isolation of apigenin, which may be responsible for CNS-effects of T. parthenium extracts.

  16. Submerged fermentation of Lactobacillus rhamnosus YS9 for γ-aminobutyric acid (GABA production

    Directory of Open Access Journals (Sweden)

    Qian Lin


    Full Text Available γ-Aminobutyric acid (GABA is a major inhibitory neurotransmitter in central nervous system, and its application in drugs and functional foods has attracted great attention. To enhance production of y-aminobutyric acid, Lactobacillus rhamnosus YS9, a strain isolated from Chinese traditional fermented food pickled vegetable, was grown under submerged fermentation. Its cultivation conditions were investigated. When culture pH condition was adjusted to the optimal pH of glutamate decarboxylase activity, culture of Lb. rhamnosus YS9 in medium supplemented with 200 mM of monosodium glutamate and 200 µM of pyridoxal phosphate (PLP, produced 187 mM of GABA.

  17. Mutations in the GABA Transporter SLC6A1 Cause Epilepsy with Myoclonic-Atonic Seizures

    DEFF Research Database (Denmark)

    Carvill, Gemma L; McMahon, Jacinta M; Schneider, Amy


    GAT-1, encoded by SLC6A1, is one of the major gamma-aminobutyric acid (GABA) transporters in the brain and is responsible for re-uptake of GABA from the synapse. In this study, targeted resequencing of 644 individuals with epileptic encephalopathies led to the identification of six SLC6A1 mutations...... of the electrophysiological properties of Gat1-deficient mice, including spontaneous spike-wave discharges. Overall, pathogenic mutations occurred in 6/160 individuals with MAE, accounting for ~4% of unsolved MAE cases....

  18. Endogenous synthesis of corticosteroids in the hippocampus.

    Directory of Open Access Journals (Sweden)

    Shimpei Higo

    Full Text Available BACKGROUND: Brain synthesis of steroids including sex-steroids is attracting much attention. The endogenous synthesis of corticosteroids in the hippocampus, however, has been doubted because of the inability to detect deoxycorticosterone (DOC synthase, cytochrome P450(c21. METHODOLOGY/PRINCIPAL FINDINGS: The expression of P450(c21 was demonstrated using mRNA analysis and immmunogold electron microscopic analysis in the adult male rat hippocampus. DOC production from progesterone (PROG was demonstrated by metabolism analysis of (3H-steroids. All the enzymes required for corticosteroid synthesis including P450(c21, P450(2D4, P450(11β1 and 3β-hydroxysteroid dehydrogenase (3β-HSD were localized in the hippocampal principal neurons as shown via in situ hybridization and immunoelectron microscopic analysis. Accurate corticosteroid concentrations in rat hippocampus were determined by liquid chromatography-tandem mass spectrometry. In adrenalectomized rats, net hippocampus-synthesized corticosterone (CORT and DOC were determined to 6.9 and 5.8 nM, respectively. Enhanced spinogenesis was observed in the hippocampus following application of low nanomolar (10 nM doses of CORT for 1 h. CONCLUSIONS/SIGNIFICANCE: These results imply the complete pathway of corticosteroid synthesis of 'pregnenolone →PROG→DOC→CORT' in the hippocampal neurons. Both P450(c21 and P450(2D4 can catalyze conversion of PROG to DOC. The low nanomolar level of CORT synthesized in hippocampal neurons may play a role in modulation of synaptic plasticity, in contrast to the stress effects by micromolar CORT from adrenal glands.

  19. Downregulation of GABA[Subscript A] Receptor Protein Subunits a6, ß2, d, e, ?2, ?, and ?2 in Superior Frontal Cortex of Subjects with Autism (United States)

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rustan, Oyvind G.; Rooney, Robert J.; Thuras, Paul D.


    We measured protein and mRNA levels for nine gamma-aminobutyric acid A (GABA[subscript A]) receptor subunits in three brain regions (cerebellum, superior frontal cortex, and parietal cortex) in subjects with autism versus matched controls. We observed changes in mRNA for a number of GABA[subscript A] and GABA[subscript B] subunits and overall…

  20. GABA and its B-receptor are present at the node of Ranvier in a small population of sensory fibers, implicating a role in myelination

    DEFF Research Database (Denmark)

    Corell, Mikael; Wicher, Grzegorz; Radomska, Katarzyna J


    The γ-aminobutyric acid (GABA) type B receptor has been implicated in glial cell development in the peripheral nervous system (PNS), although the exact function of GABA signaling is not known. To investigate GABA and its B receptor in PNS development and degeneration, we studied the expression...

  1. Transfection of small RNAs globally perturbs gene regulation by endogenous microRNAs

    DEFF Research Database (Denmark)

    Khan, Aly A; Betel, Doron; Miller, Martin L


    among the transfected small RNAs and the endogenous pool of miRNAs for the intracellular machinery that processes small RNAs. To test this hypothesis, we analyzed genome-wide transcript responses from 151 published transfection experiments in seven different human cell types. We show that targets......Transfection of small RNAs (such as small interfering RNAs (siRNAs) and microRNAs (miRNAs)) into cells typically lowers expression of many genes. Unexpectedly, increased expression of genes also occurs. We investigated whether this upregulation results from a saturation effect--that is, competition...... of endogenous miRNAs are expressed at significantly higher levels after transfection, consistent with impaired effectiveness of endogenous miRNA repression. This effect exhibited concentration and temporal dependence. Notably, the profile of endogenous miRNAs can be largely inferred by correlating miRNA sites...

  2. The Role of Endogenous H(2)S in Cardiovascular Physiology

    DEFF Research Database (Denmark)

    Skovgaard, Nini; Gouliaev, Anja; Aalling, Mathilde


    Recent research has shown that the endogenous gas hydrogen sulphide (H(2)S) is a signalling molecule of considerable biological potential and has been suggested to be involved in a vast number of physiological processes. In the vascular system, H(2)S is synthesized from cysteine by cystathionine......-γ-lyase (CSE) in smooth muscle cells (SMC) and 3-mercaptopyruvate sulfuresterase (3MST) and CSE in the endothelial cells. In pulmonary and systemic arteries, H(2)S induces relaxation and/or contraction dependent on the concentration of H(2)S, type of vessel and species. H(2)S relaxes SMC through a direct...

  3. Evolution and phylogeny of insect endogenous retroviruses. (United States)

    Terzian, C; Pélisson, A; Bucheton, A


    The genome of invertebrates is rich in retroelements which are structurally reminiscent of the retroviruses of vertebrates. Those containing three open reading frames (ORFs), including an env-like gene, may well be considered as endogenous retroviruses. Further support to this similarity has been provided by the ability of the env-like gene of DmeGypV (the Gypsy endogenous retrovirus of Drosophila melanogaster) to promote infection of Drosophila cells by a pseudotyped vertebrate retrovirus vector. To gain insights into their evolutionary story, a sample of thirteen insect endogenous retroviruses, which represents the largest sample analysed until now, was studied by computer-assisted comparison of the translated products of their gag, pol and env genes, as well as their LTR structural features. We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements. We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS). We propose to name IERV-K and IERV-S these two major subgroups of Insect Endogenous Retro Viruses (or Insect ERrantiVirus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.

  4. [Endogenous digoxin-like factor in myocardial infarction]. (United States)

    Bagrov, A I; Kuznetsova, E A; Fedorova, O V


    The main aim of the study was to test the hypotheses that (a) concentrations of endogenous digoxin-like factor (EDLF) are increased in the initial period after acute myocardial infarction (AMI) and (b) may contribute to the onset of ventricular arrhythmias. 54 patients of both sexes with a first transmural AMI were included in a retrospective study. Plasma concentrations of EDLF were measured repeatedly during days 1-14 after AMI using DELFIA digoxin fluoroimmunoassay. 16 male patients with unstable angina pectoris and suspected AMI as well as 8 healthy subjects of both sexes served as controls. Plasma concentrations of EDLF in patients during the first day of AMI were increased (1.25 + (-)0.26 ng/ml, digoxin equivalents, p myocardial ischemia-induced arrhythmogenesis and participate in pathogenesis of congestive heart failure after AMI.

  5. The GABA(A) receptor RDL acts in peptidergic PDF neurons to promote sleep in Drosophila. (United States)

    Chung, Brian Y; Kilman, Valerie L; Keath, J Russel; Pitman, Jena L; Allada, Ravi


    Sleep is regulated by a circadian clock that times sleep and wake to specific times of day and a homeostat that drives sleep as a function of prior wakefulness. To analyze the role of the circadian clock, we have used the fruit fly Drosophila. Flies display the core behavioral features of sleep, including relative immobility, elevated arousal thresholds, and homeostatic regulation. We assessed sleep-wake modulation by a core set of circadian pacemaker neurons that express the neuropeptide PDF. We find that disruption of PDF function increases sleep during the late night in light:dark and the first subjective day of constant darkness. Flies deploy genetic and neurotransmitter pathways to regulate sleep that are similar to those of their mammalian counterparts, including GABA. We find that RNA interference-mediated knockdown of the GABA(A) receptor gene, Resistant to dieldrin (Rdl), in PDF neurons reduces sleep, consistent with a role for GABA in inhibiting PDF neuron function. Patch-clamp electrophysiology reveals GABA-activated picrotoxin-sensitive chloride currents on PDF+ neurons. In addition, RDL is detectable most strongly on the large subset of PDF+ pacemaker neurons. These results suggest that GABAergic inhibition of arousal-promoting PDF neurons is an important mode of sleep-wake regulation in vivo.

  6. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA (United States)

    Nesterkina, Mariia; Kravchenko, Iryna


    Novel esters of γ-aminobutyric acid (GABA) with monocyclic terpenes were synthesized via Steglich esterification and characterized by 1H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate acute pain more than the reference drug benzocaine after their topical application. GABA esters of l-menthol and thymol were also shown to exceed the reference drug ibuprofen in their ability to decrease the inflammatory state induced by intraplantar injection of the TRPA1 activator AITC. The present findings indicate that GABA esters of carvacrol and guaiacol are not a classical prodrug and possess their own pharmacological activity. Prolonged antiseizure action of the ester based on the amino acid and guaiacol (200 mg/kg) was revealed at 24 h after oral administration. Furthermore, orally co-administered gidazepam (1 mg/kg) and GABA esters of l-menthol, thymol and carvacrol produce synergistic seizure prevention effects. PMID:27304960

  7. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA

    Directory of Open Access Journals (Sweden)

    Mariia Nesterkina


    Full Text Available Novel esters of γ-aminobutyric acid (GABA with monocyclic terpenes were synthesized via Steglich esterification and characterized by 1H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate acute pain more than the reference drug benzocaine after their topical application. GABA esters of l-menthol and thymol were also shown to exceed the reference drug ibuprofen in their ability to decrease the inflammatory state induced by intraplantar injection of the TRPA1 activator AITC. The present findings indicate that GABA esters of carvacrol and guaiacol are not a classical prodrug and possess their own pharmacological activity. Prolonged antiseizure action of the ester based on the amino acid and guaiacol (200 mg/kg was revealed at 24 h after oral administration. Furthermore, orally co-administered gidazepam (1 mg/kg and GABA esters of l-menthol, thymol and carvacrol produce synergistic seizure prevention effects.

  8. The Subcellular Localization of GABA Transporters and Its Implication for Seizure Management

    DEFF Research Database (Denmark)

    Madsen, Karsten K; Hansen, Gert H; Danielsen, E Michael


    anticonvulsant effect in several seizure models in mice. The pharmacological profile of these and similar compounds has been thoroughly investigated in in vitro systems, comparing the GAT subtype selectivity with the ability to inhibit GABA uptake in primary cultures of neurons and astrocytes. However, an exact...

  9. Contributions of GABA to alcohol responsivity during adolescence: Insights from preclinical and clinical studies (United States)

    Silveri, Marisa M.


    There is a considerable body of literature demonstrating that adolescence is a unique age period, which includes rapid and dramatic maturation of behavioral, cognitive, hormonal and neurobiological systems. Most notably, adolescence is also a period of unique responsiveness to alcohol effects, with both hyposensitivity and hypersensitivity observed to the various effects of alcohol. Multiple neurotransmitter systems are undergoing fine-tuning during this critical period of brain development, including those that contribute to the rewarding effects of drugs of abuse. The role of developmental maturation of the γ-amino-butyric acid (GABA) system, however, has received less attention in contributing to age-specific alcohol sensitivities. This review integrates GABA findings from human magnetic resonance spectroscopy studies as they may translate to understanding adolescent-specific responsiveness to alcohol effects. Better understanding of the vulnerability of the GABA system both during adolescent development, and in psychiatric conditions that include alcohol dependence, could point to a putative mechanism, boosting brain GABA, that may have increased effectiveness for treating alcohol abuse disorders. PMID:24631274

  10. GABA-modulating phytomedicines for anxiety: A systematic review of preclinical and clinical evidence. (United States)

    Savage, Karen; Firth, Joseph; Stough, Con; Sarris, Jerome


    Anxiety disorders are chronic and functionally disabling conditions with high psychological stress, characterised by cognitive symptoms of excessive worry and focus difficulties and physiological symptoms such as muscle tension and insomnia. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter within the central nervous system and is a key target of pharmacotherapies in the treatment of anxiety. Although current pharmaceutical treatments are often efficacious, they may cause undesirable side effects including cognitive decrements and withdrawal symptoms. Plant-based "phytomedicines" may provide novel treatment options, to act as an adjunctive or alternative to existing anxiolytic medications. As such, we conducted a systematic review to assess the current body of literature on anxiolytic phytomedicines and/or phytoconstituents. An open-ended search to 5 July 2017 was conducted using MEDLINE (PubMed), Scopus, and Cochrane library online databases and performed in a stepped format from preclinical to clinical investigations. Eligible studies must have had (a) in vitro evidence of GABA-modulating activity, (b) animal studies using anxiety models to test an anxiolytic effect, and (c) human clinical trials. Ten phytomedicines were identified as having preclinical investigations showing interaction with the GABA system, in addition to human clinical trials: kava, valerian, pennywort, hops, chamomile, Ginkgo biloba, passionflower, ashwagandha, skullcap, and lemon balm. Collectively, the literature reveals preclinical and clinical evidence for various phytomedicines modulating GABA-pathways, with comparative anxiolytic effect to the current array of pharmaceuticals, along with good safety and tolerability profiles. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Terpene trilactones from Ginkgo biloba are antagonists of cortical glycine and GABA(A) receptors. (United States)

    Ivic, Lidija; Sands, Tristan T J; Fishkin, Nathan; Nakanishi, Koji; Kriegstein, Arnold R; Strømgaard, Kristian


    Glycine and gamma-aminobutyric acid, type A (GABA(A)) receptors are members of the ligand-gated ion channel superfamily that mediate inhibitory synaptic transmission in the adult central nervous system. During development, the activation of these receptors leads to membrane depolarization. Ligands for the two receptors have important implications both in disease therapy and as pharmacological tools. Terpene trilactones (ginkgolides and bilobalide) are unique constituents of Ginkgo biloba extracts that have various effects on the central nervous system. We have investigated the relative potency of these compounds on glycine and GABA(A) receptors. We find that most of the ginkgolides are selective and potent antagonists of the glycine receptor. Bilobalide, the single major component in G. biloba extracts, also reduces glycine-induced currents, although to a lesser extent. Both ginkgolides and bilobalide inhibit GABA(A) receptors, with bilobalide demonstrating a more potent effect. Additionally, we provide evidence that open channels are required for glycine receptor inhibition by ginkgolides. Finally, we employ molecular modeling to elucidate the similarities and differences in the structure of the terpene trilactones to account for the pharmacological properties of these compounds and demonstrate a striking similarity between ginkgolides and picrotoxinin, a GABA(A) and recombinant glycine alpha-homomeric receptor antagonist.

  12. Flavylium salts as in vitro precursors of potent ligands to brain GABA-A receptors

    DEFF Research Database (Denmark)

    Kueny-Stotz, Marie; Chassaing, Stefan; Brouillard, Raymond


    The synthesis of a series of derivatized flavylium cations was undertaken and the affinity to the benzodiazepine binding site of the GABA-A receptor evaluated. The observed high affinity for some derivatives (sub-muM range) was explained by an in vitro transformation of the flavylium cations...

  13. Synergistic GABA-Enhancing Therapy against Seizures in a Mouse Model of Dravet Syndrome (United States)

    Oakley, John C.; Cho, Alvin R.; Cheah, Christine S.; Scheuer, Todd


    Seizures remain uncontrolled in 30% of patients with epilepsy, even with concurrent use of multiple drugs, and uncontrolled seizures result in increased morbidity and mortality. An extreme example is Dravet syndrome (DS), an infantile-onset severe epilepsy caused by heterozygous loss of function mutations in SCN1A, the gene encoding the brain type-I voltage-gated sodium channel NaV1.1. Studies in Scn1a heterozygous knockout mice demonstrate reduced excitability of GABAergic interneurons, suggesting that enhancement of GABA signaling may improve seizure control and comorbidities. We studied the efficacy of two GABA-enhancing drugs, clonazepam and tiagabine, alone and in combination, against thermally evoked myoclonic and generalized tonic-clonic seizures. Clonazepam, a positive allosteric modulator of GABA-A receptors, protected against myoclonic and generalized tonic-clonic seizures. Tiagabine, a presynaptic GABA reuptake inhibitor, was protective against generalized tonic-clonic seizures but only minimally protective against myoclonic seizures and enhanced myoclonic seizure susceptibility at high doses. Combined therapy with clonazepam and tiagabine was synergistic against generalized tonic-clonic seizures but was additive against myoclonic seizures. Toxicity determined by rotorod testing was additive for combination therapy. The synergistic actions of clonazepam and tiagabine gave enhanced seizure protection and reduced toxicity, suggesting that combination therapy may be well tolerated and effective for seizures in DS. PMID:23424217

  14. Increased glutamate/GABA+ ratio in a shared autistic and schizotypal trait phenotype termed Social Disorganisation

    Directory of Open Access Journals (Sweden)

    Talitha C. Ford


    Results suggest that a higher expression of the SD phenotype may be associated with increased glutamate/GABA+ ratio in the right ST region, which may affect speech prosody processing, and lead behavioural characteristics that are shared within the autistic and schizotypal spectra.

  15. Neuronal and non-neuronal GABA transporters as targets for antiepileptic drugs

    DEFF Research Database (Denmark)

    Madsen, Karsten K; White, H Steve; Schousboe, Arne


    Epileptic seizure activity is associated with an imbalance between excitatory and inhibitory synaptic activities. The latter is mediated by GABA, and several currently used antiepileptic drugs target entities of the GABAergic synapse such as the receptors or the inactivation mechanism consisting ...

  16. Homology Modelling of the GABA Transporter and Analysis of Tiagabine Binding

    DEFF Research Database (Denmark)

    Skovstrup, S.; Taboureau, Olivier; Bräuner-Osborne, H.


    A homology model of the human GABA transporter (GAT-1) based on the recently reported crystal structures of the bacterial leucine transporter from Aquifex aeolicus (LeuT) was developed. The stability of the resulting model embedded in a membrane environment was analyzed by extensive molecular...

  17. Quasi-morphine abstinence behaviour GABA-ergic mechanisms and their localization

    NARCIS (Netherlands)

    J.W. van der Laan


    textabstractDi-n-propylacetate (DPA), generally known to be an anti-epileptic drug, induces a behavioural syndrome in rats resembling morphine abstinence behaviour, which is called, therefore, quasi-morphine abstinence beh~viour. An increase in GABA-ergic activity is probably responsible for this

  18. Epilepsy in succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism

    NARCIS (Netherlands)

    Pearl, P.L.; Shukla, L.; Theodore, W.H.; Jakobs, C.A.J.M.; Gibson, K.M.


    Objectives: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a gamma-aminobutyric acid (GABA) degradative defect. Epilepsy affects half of patients. The murine model is associated with a transition from absence to convulsive seizures in the third week, with fatal status epilepticus.

  19. GABA-Mediated Presynaptic Inhibition Is Required for Precision of Long-Term Memory (United States)

    Cullen, Patrick K.; Dulka, Brooke N.; Ortiz, Samantha; Riccio, David C.; Jasnow, Aaron M.


    Though much attention has been given to the neural structures that underlie the long-term consolidation of contextual memories, little is known about the mechanisms responsible for the maintenance of memory precision. Here, we demonstrate a rapid time-dependent decline in memory precision in GABA [subscript B(1a)] receptor knockout mice. First, we…

  20. GABA[subscript A] Receptors Determine the Temporal Dynamics of Memory Retention (United States)

    McNally, Gavan P.; Augustyn, Katarzyna A.; Richardson, Rick


    Four experiments studied the role of GABA[subscript A] receptors in the temporal dynamics of memory retention. Memory for an active avoidance response was a nonmonotonic function of the retention interval. When rats were tested shortly (2 min) or some time (24 h) after training, retention was excellent, but when they were tested at intermediate…

  1. Sarcoglycans and gaba(a) receptors in rat central nervous system: an immunohistochemical study. (United States)

    Cutroneo, Giuseppina; Bramanti, Placido; Anastasi, Giuseppe; Bruschetta, Daniele; Favaloro, Angelo; Vermiglio, Giovanna; Trimarchl, Fabio; Di Mauro, Debora; Rizzo, Giuseppina


    Sarcoglycan subcomplex is a transmembrane glycoprotein system which connects extracellular matrix to cytoskeleton. Although this complex has been found in several non-muscular tissues, no data exist about a sarcoglycan subcomplex in brain. Only the presence of ε-sarcoglycan in brain has been described in detail because its mutation determines Myoclonus Dystonia Syndrome. Also ζ-, β- and δ-sarcoglycans have been found in brain but only at mRNA level and their distribution in brain is still unknown. Here, we have searched for the expression of all sarcoglycans in specific brain regions of rat as hippocampus, cerebral and cerebellar cortex. Since a correlation between dystrophin glycoprotein complex and γ-amino butyric acid A (GABA(A)) receptor was demonstrated, we have investigated also a possible colocalization between sarcoglycans and GABA(A) receptor. Results have shown that all sarcoglycans are expressed in neurons of all observed regions; these proteins show a spot-like pattern of fluorescence and are mainly localized at soma level. Moreover, each sarcoglycan colocalizes with GABA(A) receptor. The present study shows, for the first time, the expression of all sarcoglycans in brain; moreover, the prevalent localization of sarcoglycans at post-synaptic level and the colocalization of these glycoproteins with GABA(A) receptor suggests that sarcoglycans play a key role in central nervous system, regulating post-synaptic receptors assembly.

  2. Activity-dependent endogenous taurine release facilitates excitatory neurotransmission in the neocortical marginal zone of neonatal rats

    Directory of Open Access Journals (Sweden)

    Taizhe eQian


    Full Text Available In the developing cerebral cortex, the marginal zone (MZ, consisting of early-generated neurons such as Cajal-Retzius cells, plays an important role in cell migration and lamination. There is accumulating evidence of widespread excitatory neurotransmission mediated by γ-aminobutyric acid (GABA in the MZ. Cajal-Retzius cells express not only GABAA receptors but also α2/β subunits of glycine receptors, and exhibit glycine receptor-mediated depolarization due to high [Cl−]i. However, the physiological roles of glycine receptors and their endogenous agonists during neurotransmission in the MZ are yet to be elucidated. To address this question, we performed optical imaging from the MZ using the voltage-sensitive dye JPW1114 on tangential neocortical slices of neonatal rats. A single electrical stimulus evoked an action-potential-dependent optical signal that spread radially over the MZ. The amplitude of the signal was not affected by glutamate receptor blockers, but was suppressed by either GABAA or glycine receptor antagonists. Combined application of both antagonists nearly abolished the signal. Inhibition of Na+, K+-2Cl− cotransporter by 20 µM bumetanide reduced the signal, indicating that this transporter contributes to excitation. Analysis of the interstitial fluid obtained by microdialysis from tangential neocortical slices with high-performance liquid chromatography revealed that GABA and taurine, but not glycine or glutamate, were released in the MZ in response to the electrical stimulation. The ambient release of taurine was reduced by the addition of a voltage-sensitive Na+ channel blocker. Immunohistochemistry and immunoelectron microscopy indicated that taurine was stored both in Cajal-Retzius and non-Cajal-Retzius cells in the MZ, but was not localized in presynaptic structures. Our results suggest that activity-dependent non-synaptic release of endogenous taurine facilitates excitatory neurotransmission through activation of

  3. Maintenance, endogeneous, respiration, lysis, decay and predation

    DEFF Research Database (Denmark)

    loosdrecht, Marc C. M. Van; Henze, Mogens


    mechanism is microbiologically correct. The lysis/decay model mechanism is a strongly simplified representation of reality. This paper tries to review the processes grouped under endogenous respiration in activated sludge models. Mechanisms and processes such as maintenance, lysis, internal and external...... and maintenance processes. This conversion will in general be denoted as endogenous respiration. Based on the literature review the phenomena are discussed and organised, in order to create a working platform for discussing more detailed activated sludge models, one of which is being sketched. (C) 1999 IAWQ......In activated sludge processes an increased sludge age is associated with a decreased sludge production. This phenomenon is generally interpreted as a result of endogenous respiration processes. In the activated sludge models cell lysis (or decay) is incorporated. The lysis is modelled...

  4. Endogeneity in Strategy-Performance Analysis

    DEFF Research Database (Denmark)

    Rocha, Vera; Van Praag, Mirjam; B. Folta, Timothy


    Managers engage in a variety of strategies, not randomly, but having in mind their performance implications. Therefore, strategic choices are endogenous in performance equations. Despite increasing efforts by various scholars in solving endogeneity bias, prior attempts have almost exclusively......, such as employees, strategic partners, customers, or investors, whose choices and preferences also affect the final decision. We discuss how endogeneity can plague the measurement of the performance effects of these two-sided strategic decisions—which are more complex, but more realistic, than prior representations...... of organizational decision making. We provide an empirical demonstration of possible methods to deal with three different sources of bias, by analyzing the performance effects of two human capital choices made by founders at startup: the size and average quality of the initial workforce....

  5. An Overview of the CNS-Pharmacodynamic Profiles of Nonselective and Selective GABA Agonists

    Directory of Open Access Journals (Sweden)

    Xia Chen


    Full Text Available Various 2,3 subtype selective partial GABA-A agonists are in development to treat anxiety disorders. These compounds are expected to be anxiolytic with fewer undesirable side effects, compared to nonselective GABA-A agonists like benzodiazepines. Several 2,3 subtype selective and nonselective GABA-A agonists have been examined in healthy volunteers, using a battery addressing different brain domains. Data from five placebo-controlled double-blind studies were pooled. Lorazepam 2 mg was the comparator in three studies. Three 2,3-selective GABAA agonists (i.e., TPA023, TPACMP2, SL65.1498, one 1-selective GABAA agonists (zolpidem, and another full agonist (alprazolam were examined. Pharmacological selectivity was assessed by determination of regression lines for the change from baseline of saccadic-peak-velocity- (ΔSPV- relative effect, relative to changes in different pharmacodynamic endpoints (ΔPD. SPV was chosen for its sensitivity to the anxiolysis of benzodiazepines. Slopes of the ΔSPV-ΔPD relations were consistently lower with the 2,3 selective GABA-A agonists than with lorazepam, indicating that their PD effects are less than their SPV-effects. The ΔSPV-ΔPD relations of lorazepam were comparable to alprazolam. Zolpidem showed relatively higher impairments in ΔPD relative to ΔSPV, but did not significantly differ from lorazepam. These PD results support the pharmacological selectivity of the 2,3-selective GABA-A agonists, implying an improved therapeutic window.

  6. (R)-(3-amino-2-fluoropropyl) phosphinic acid (AZD3355), a novel GABAB receptor agonist, inhibits transient lower esophageal sphincter relaxation through a peripheral mode of action

    DEFF Research Database (Denmark)

    Lehmann, Anders; Antonsson, Madeleine; Holmberg, Ann Aurell


    brain; AZD3355, but not baclofen, was concentrated in circumventricular organs as a result of active uptake (shown by avid intracellular sequestration) and related to binding of AZD3355 to native GABA transporters in rat cerebrocortical membranes. AZD3355 was also shown to be transported by all four......Gastroesophageal reflux disease (GERD) affects >10% of the Western population. Conventionally, GERD is treated by reducing gastric acid secretion, which is effective in most patients but inadequate in a significant minority. We describe a new therapeutic approach for GERD, based on inhibition...... recombinant human GABA transporters. AR-H061719 [(R/S)-(3-amino-2-fluoropropyl)phosphinic acid], (the racemate of AZD3355) inhibited the response of ferret mechanoreceptors to gastric distension, further supporting its peripheral site of action on TLESR. In summary, AZD3355 probably inhibits TLESR through...

  7. Activation of extrasynaptic GABA(A) receptors inhibits cyclothiazide-induced epileptiform activity in hippocampal CA1 neurons. (United States)

    Wan, Li; Liu, Xu; Wu, Zheng; Ren, Wanting; Kong, Shuzhen; Dargham, Raya Abou; Cheng, Longzhen; Wang, Yun


    Extrasynaptic GABA(A) receptors (GABA(A)Rs)-mediated tonic inhibition is reported to involve in the pathogenesis of epilepsy. In this study, we used cyclothiazide (CTZ)-induced in vitro brain slice seizure model to explore the effect of selective activation of extrasynaptic GABA(A)Rs by 4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridine-3-ol (THIP) on the CTZ-induced epileptiform activity in hippocampal neurons. Perfusion with CTZ dose-dependently induced multiple epileptiform peaks of evoked population spikes (PSs) in CA1 pyramidal neurons, and treatment with THIP (5 μmol/L) significantly reduced the multiple PS peaks induced by CTZ stimulation. Western blot showed that the δ-subunit of the GABA(A)R, an extrasynaptic specific GABA(A)R subunit, was also significantly down-regulated in the cell membrane 2 h after CTZ treatment. Our results suggest that the CTZ-induced epileptiform activity in hippocampal CA1 neurons is suppressed by the activation of extrasynaptic GABA(A)Rs, and further support the hypothesis that tonic inhibition mediated by extrasynaptic GABA(A)Rs plays a prominent role in seizure generation.

  8. Contingent and non-contingent effects of low-dose ethanol on GABA neuron activity in the ventral tegmental area (United States)

    Steffensen, Scott C.; Walton, Christine H.; Hansen, David M.; Yorgason, Jordan T.; Gallegos, Roger A.; Criado, Jose R.


    Ventral tegmental area (VTA) GABA neurons appear to be critical regulators of mesocorticolimbic dopamine (DA) neurotransmission, which has been implicated in alcohol reward. The aim of this study was to evaluate the effects of low-dose “non-contingent” intravenous (IV) ethanol (0.01–0.1 g/kg) on VTA GABA neuron firing rate and synaptic responses, as well as VTA GABA neuron firing rate during low-dose “contingent” IV ethanol self-administration. Intravenous administration of 0.01–0.03 g/kg ethanol significantly increased VTA GABA neuron firing rate and afferent-evoked synaptic responses. In the runway self-administration paradigm, presentation of an olfactory cue (S+; almond extract) or no-cue (S−; no odor) in the Start box was paired with IV administration of low-dose ethanol (0.01 g/kg) or saline in the Target box. Runway excursion times decreased significantly in association during S+, and increased significantly during S− conditions. The firing rate of VTA GABA neurons markedly increased when rats received 0.01 g/kg IV ethanol in the Target box. VTA GABA neuron firing increased in the Start box of the runway in association with S+, but not S−. These findings demonstrate that VTA GABA neurons are activated by low-dose IV ethanol and that their firing rate increases in anticipation of ethanol reward. PMID:18996142

  9. Endogenous network of firms and systemic risk (United States)

    Ma, Qianting; He, Jianmin; Li, Shouwei


    We construct an endogenous network characterized by commercial credit relationships connecting the upstream and downstream firms. Simulation results indicate that the endogenous network model displays a scale-free property which exists in real-world firm systems. In terms of the network structure, with the expansion of the scale of network nodes, the systemic risk increases significantly, while the heterogeneities of network nodes have no effect on systemic risk. As for firm micro-behaviors, including the selection range of trading partners, actual output, labor requirement, price of intermediate products and employee salaries, increase of all these parameters will lead to higher systemic risk.

  10. An endogenous model of the credit network (United States)

    He, Jianmin; Sui, Xin; Li, Shouwei


    In this paper, an endogenous credit network model of firm-bank agents is constructed. The model describes the endogenous formation of firm-firm, firm-bank and bank-bank credit relationships. By means of simulations, the model is capable of showing some obvious similarities with empirical evidence found by other scholars: the upper-tail of firm size distribution can be well fitted with a power-law; the bank size distribution can be lognormally distributed with a power-law tail; the bank in-degrees of the interbank credit network as well as the firm-bank credit network fall into two-power-law distributions.

  11. GABA(A) receptors in the dorsal raphé nucleus of mice: escalation of aggression after alcohol consumption. (United States)

    Takahashi, Aki; Kwa, Carolyn; Debold, Joseph F; Miczek, Klaus A


    The dorsal raphé nucleus (DRN), the origin for serotonin (5-HT) in forebrain areas, has been implicated in the neural control of escalated aggression. Gamma aminobutyric acid type-A (GABA(A)) and type-B (GABA(B)) receptors are expressed in the DRN and modulate 5-HT neuronal activity, and both play a role in the behavioral effect of alcohol. The purpose of this study is to examine the interaction between drugs acting on GABA receptors in the DRN and alcohol in their effects on aggressive behaviors. Male CFW mice, housed with a female, were trained to self-administer ethanol (1.0 g/kg) or water via an operant conditioning panel in their home cage. Immediately after they drank either ethanol or water, the animals were microinfused with a GABAergic drug into the DRN, and their aggressive behaviors were assessed 10 min later. Muscimol (0.006 nmol), a GABA(A) receptor agonist, escalated alcohol-heightened aggression but had no effect in the absence of ethanol. This effect of muscimol was prominent in the animals that showed alcohol-heightened aggression, but not the animals that reduced or did not change aggressive behavior after ethanol infusion compared to water. On the other hand, the GABA(B) agonist baclofen (0.06 nmol) increased aggressive behavior similarly in both water and ethanol conditions. Antagonists of the GABA(A) and GABA(B) receptors, bicuculline (0.006 nmol) and phaclofen (0.3 nmol) respectively, did not suppress heightened-aggressive behavior induced by ethanol self-administration. GABA(A) receptors in the DRN are one of the neurobiological targets of alcohol-heightened aggression. Activation of the GABA(B) receptors in the DRN also produced escalated aggression, but that is independent of the effect of alcohol.

  12. Reconstruction of a metabolic regulatory network in Escherichia coli for purposeful switching from cell growth mode to production mode in direct GABA fermentation from glucose. (United States)

    Soma, Yuki; Fujiwara, Yuri; Nakagawa, Takuya; Tsuruno, Keigo; Hanai, Taizo


    γ-aminobutyric acid (GABA) is a drug and functional food additive and is used as a monomer for producing the biodegradable plastic, polyamide 4. Recently, direct GABA fermentation from glucose has been developed as an alternative to glutamate-based whole cell bioconversion. Although total productivity in fermentation is determined by the specific productivity and cell amount responsible for GABA production, the optimal metabolic state for GABA production conflicts with that for bacterial cell growth. Herein, we demonstrated metabolic state switching from the cell growth mode based on the metabolic pathways of the wild type strain to a GABA production mode based on a synthetic metabolic pathway in Escherichia coli through rewriting of the metabolic regulatory network and pathway engineering. The GABA production mode was achieved by multiple strategies such as conditional interruption of the TCA and glyoxylate cycles, engineering of GABA production pathway including a bypass for precursor metabolite supply, and upregulation of GABA transporter. As a result, we achieved 3-fold improvement in total GABA production titer and yield (4.8g/L, 49.2% (mol/mol glucose)) in batch fermentation compared to the case without metabolic state switching (1.6g/L, 16.4% (mol/mol glucose)). This study reports the highest GABA production performance among previous reports on GABA fermentation from glucose using engineered E. coli. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  13. Impact of altered endogenous IgG on unspecific mAb clearance. (United States)

    Fuhrmann, Saskia; Kloft, Charlotte; Huisinga, Wilhelm


    Immunodeficient mice are crucial models to evaluate the efficacy of monoclonal antibodies (mAbs). When studying mAb pharmacokinetics (PK), protection from elimination by binding to the neonatal Fc receptor (FcRn) is known to be a major process influencing the unspecific clearance of endogenous and therapeutic IgG. The concentration of endogenous IgG in immunodeficient mice, however is reduced, and this effect on the FcRn protection mechanism and subsequently on unspecific mAb clearance is unknown, yet of great importance for the interpretation of mAb PK data. We used a PBPK modelling approach to elucidate the influence of altered endogenous IgG concentrations on unspecific mAb clearance. To this end, we used PK data in immunodeficient mice, i.e. nude and severe combined immunodeficiency mice. To avoid impact of target-mediated clearance processes, we focussed on mAbs without affinity to a target antigen in these mice. In addition, intravenous immunoglobulin (IVIG) data of immunocompetent mice was used to study the impact of increased total IgG concentrations on unspecific therapeutic antibody clearance. The unspecific clearance is linear, whenever therapeutic IgG concentrations, i.e. mAb and IVIG concentrations are lower than FcRn; it can be non-linear if therapeutic IgG concentrations are larger than FcRn and endogenous IgG concentrations (e.g., under IVIG therapy). Unspecific mAb clearance of immunodeficient mice is effectively linear (under mAb doses as typically used in human). Studying the impact of reduced endogenous IgG concentrations on unspecific mAb clearance is of great relevance for the extrapolation to clinical species, e.g., when predicting mAb PK in immunosuppressed cancer patients.

  14. Combining antigen-based therapy with GABA treatment synergistically prolongs survival of transplanted ß-cells in diabetic NOD mice.

    Directory of Open Access Journals (Sweden)

    Jide Tian

    Full Text Available Antigen-based therapies (ABTs very effectively prevent the development of type 1 diabetes (T1D when given to young nonobese diabetic (NOD mice, however, they have little or no ability to reverse hyperglycemia in newly diabetic NOD mice. More importantly, ABTs have not yet demonstrated an ability to effectively preserve residual ß-cells in individuals newly diagnosed with type 1 diabetes (T1D. Accordingly, there is great interest in identifying new treatments that can be combined with ABTs to safely protect ß-cells in diabetic animals. The activation of γ-aminobutyric acid (GABA receptors (GABA-Rs on immune cells has been shown to prevent T1D, experimental autoimmune encephalomyelitis (EAE and rheumatoid arthritis in mouse models. Based on GABA's ability to inhibit different autoimmune diseases and its safety profile, we tested whether the combination of ABT with GABA treatment could prolong the survival of transplanted ß-cells in newly diabetic NOD mice. Newly diabetic NOD mice were untreated, or given GAD/alum (20 or 100 µg and placed on plain drinking water, or water containing GABA (2 or 6 mg/ml. Twenty-eight days later, they received syngenic pancreas grafts and were monitored for the recurrence of hyperglycemia. Hyperglycemia reoccurred in the recipients given plain water, GAD monotherapy, GABA monotherapy, GAD (20 µg+GABA (2 mg/ml, GAD (20 µg+GABA (6 mg/ml and GAD (100 µg+GABA (6 mg/ml about 1, 2-3, 3, 2-3, 3-8 and 10-11 weeks post-transplantation, respectively. Thus, combined GABA and ABT treatment had a synergistic effect in a dose-dependent fashion. These findings suggest that co-treatment with GABA (or other GABA-R agonists may provide a new strategy to safely enhance the efficacy of other therapeutics designed to prevent or reverse T1D, as well as other T cell-mediated autoimmune diseases.

  15. Place branding, embeddedness and endogenous rural development

    NARCIS (Netherlands)

    Donner, Mechthild; Horlings, Lummina; Fort, Fatiha; Vellema, Sietze


    This article deals with place branding on the regional scale, in the rural context of food and tourism networks in Europe. Place branding is linked to the concepts of endogenous rural development, territory and embeddedness, by analysing how the valorisation of specific rural assets takes shape.

  16. Leveraging Endogenous Research and Innovation for Sustainable ...

    African Journals Online (AJOL)

    In this treatise, a quick look is taken at the spectrum (range) of research from pure basic, strategic basic, applied, experimental development or research and development (R&D) to endogenous research and innovation (ER&I). It also defines development, innovation, food security, poverty; and discusses some contemporary ...

  17. Exogenous and endogenous corticosterone alter feather quality. (United States)

    DesRochers, David W; Reed, J Michael; Awerman, Jessica; Kluge, Jonathan A; Wilkinson, Julia; van Griethuijsen, Linnea I; Aman, Joseph; Romero, L Michael


    We investigated how exogenous and endogenous glucocorticoids affect feather replacement in European starlings (Sturnus vulgaris) after approximately 56% of flight feathers were removed. We hypothesized that corticosterone would retard feather regrowth and decrease feather quality. After feather regrowth began, birds were treated with exogenous corticosterone or sham implants, or endogenous corticosterone by applying psychological or physical (food restriction) stressors. Exogenous corticosterone had no impact on feather length and vane area, but rectrices were lighter than controls. Exogenous corticosterone also decreased inter-barb distance for all feathers and increased barbule number for secondaries and rectrices. Although exogenous corticosterone had no affect on rachis tensile strength and stiffness, barbicel hooking strength was reduced. Finally, exogenous corticosterone did not alter the ability of Bacillus licheniformis to degrade feathers or affect the number of feathers that failed to regrow. In contrast, endogenous corticosterone via food restriction resulted in greater inter-barb distances in primaries and secondaries, and acute and chronic stress resulted in greater inter-barb distances in rectrices. Food-restricted birds had significantly fewer barbules in primaries than chronic stress birds and weaker feathers compared to controls. We conclude that, although exogenous and endogenous corticosterone had slightly different effects, some flight feathers grown in the presence of high circulating corticosterone are lighter, potentially weaker, and with altered feather micro-structure.

  18. Optimized Formation of Benzyl Isothiocyanate by Endogenous ...

    African Journals Online (AJOL)

    Purpose: To use endogenous myrosinase in Carica papaya seed to convert benzyl glucosinolate (BG) to benzyl isothiocyanate (BITC) and then extract it for further studies. Methods: Process variables including seed powder particle size, sample-to-solvent ratio, pH of buffer solution, enzymolysis temperature, enzymolysis ...

  19. endogenous retrovirus sequences expressed in male mammalian

    African Journals Online (AJOL)


    Jan 2, 2002 ... demonstrated in New Zealand Black mice, where the reproductive tract of males were shown to contain C-type retrovirus(35). Also endogenous mouse mammary tumour virus (MMTV) proteins (p28 and gp47) have been identified in the epididymis and seminal vesicles of adult Swiss. Albino mice devoid of ...

  20. Managing spillovers: an endogenous sunk cost approach

    Czech Academy of Sciences Publication Activity Database

    Senyuta, Olena; Žigić, Krešimir


    Roč. 35, June (2016), s. 45-64 ISSN 0167-6245 R&D Projects: GA ČR(CZ) GAP402/12/0961 Institutional support: PRVOUK-P23 Keywords : endogenous sunk costs * innovations * knowledge spillovers Subject RIV: AH - Economics Impact factor: 0.739, year: 2016

  1. Baboon endogenous virus evolution and ecology

    NARCIS (Netherlands)

    van der Kuyl, A. C.; Dekker, J. T.; Goudsmit, J.


    Cross-species transmission of retroviruses among primates has recently been recognized as the source of the current epidemics of HIV-1, HIV-2 and human T cell leukemia virus type 1 (HTLV-1). The distribution of baboon endogenous virus among non-human primates resembles that of exogenous viruses and

  2. Immigration, Endogenous Technology Adoption and Wages

    NARCIS (Netherlands)

    Ray Chaudhuri, A.; Pandey, Manish


    We document that immigration to U.S. states has increased the mass of workers at the lower range of the skill distribution. We use this change in skill distribution of workers to analyze the effect of immigration on wages. Our model allows firms to endogenously respond to the immigration-induced

  3. An endogenous policy model of hierarchical government

    NARCIS (Netherlands)

    Mazza, I.; van Winden, F.


    Endogenous policy models usually neglect that government policies are frequently the result of decisions taken at different tiers by different agents, each enjoying some degree of autonomy. In this paper, policies are the outcome of the choices made by two agents within a hierarchy. A legislator

  4. Endogenizing technological progress: The MESEMET model

    NARCIS (Netherlands)

    P.A.G. van Bergeijk (Peter); G.H.A. van Hagen; R.A. de Mooij (Ruud); J. van Sinderen (Jarig)


    textabstractThis paper endogenizes technology and human capital formation in the MESEM model that was developed by van Sinderen (Economic Modelling, 1993, 13, 285-300). Tax allowances for private R&D expenditures and public expenditures on both education and R& D are effective instruments to

  5. Endogenous retrovirus sequences expressed in male mammalian ...

    African Journals Online (AJOL)

    In humans, one ERV family, human endogenous retrovirus- K (HERV-K) is abundantly expressed, and is associated with germ cell tumours, while ERV3 env is expressed in normal human testis. Conclusion: The expression of ERVs in male reproductive tissues suggests a possible role in normal and disease conditions ...


    African Journals Online (AJOL)

    sufficient feed. In the TME procedure, as publishecl by. Sibbald ( 1976), endogenous energy excretion is deter- mined with fasted animals, a situation which can be re- garded as being physiologically undesirable since birds would be in an energy-deficient state and to an extent also in a protein deficient state. When in a ...

  7. Applying Endogenous Knowledge in the African Context ...

    African Journals Online (AJOL)

    This requires not only an understanding of what endogenous knowledge is, but also an alignment of personal values, innovative strategies and an attitude of activism. An integral part of an extensive skills set to implement ... competence of dispute resolution practitioners in Africa. AFRICA INSIGHT Vol 42 (1) – June 2012 ...

  8. Ethnobotany and endogenous conservation of Irvingia gabonensis ...

    African Journals Online (AJOL)

    ... systematically gathered for consumption and marketing. Few studies have been done on the ethnobotany and endogenous practices determining its conservation of the species in Benin. This study aims to produce a database on those aspects in Benin. Two hundred and sixty-three people from the six major socio-cultural ...

  9. Endogenous thrombin potential in polycystic ovary syndrome

    DEFF Research Database (Denmark)

    Aziz, Mubeena; Sidelmann, Johannes J; Wissing, Marie Louise Muff


    OBJECTIVES: The objective of this study is to investigate plasma endogenous thrombin generation in four different phenotypes of polycystic ovary syndrome (PCOS) defined by Body Mass Index (BMI) and insulin resistance (IR). PCOS is diagnosed according to the Rotterdam criteria. DESIGN: Multicenter...

  10. Structures of a γ-aminobutyrate (GABA) transaminase from the s-triazine-degrading organism Arthrobacter aurescens TC1 in complex with PLP and with its external aldimine PLP–GABA adduct (United States)

    Bruce, Heather; Nguyen Tuan, Anh; Mangas Sánchez, Juan; Leese, Charlotte; Hopwood, Jennifer; Hyde, Ralph; Hart, Sam; Turkenburg, Johan P.; Grogan, Gideon


    Two complex structures of the γ-aminobutyrate (GABA) transaminase A1R958 from Arthrobacter aurescens TC1 are presented. The first, determined to a resolution of 2.80 Å, features the internal aldimine formed by reaction between the ∊-amino group of Lys295 and the cofactor pyridoxal phosphate (PLP); the second, determined to a resolution of 2.75 Å, features the external aldimine adduct formed between PLP and GABA in the first half-reaction. This is the first structure of a microbial GABA transaminase in complex with its natural external aldimine and reveals the molecular determinants of GABA binding in this enzyme. PMID:23027742

  11. Anxiety disorders and GABA neurotransmission: a disturbance of modulation

    Directory of Open Access Journals (Sweden)

    Nuss P


    Full Text Available Philippe Nuss1,21Department of Psychiatry, Hôpital St Antoine, AP-HP, 2UMR 7203, INSERM ERL 1057 – Bioactive Molecules Laboratory, Pierre and Marie Curie University, Paris, FranceAbstract: Lines of evidence coming from many branches of neuroscience indicate that anxiety disorders arise from a dysfunction in the modulation of brain circuits which regulate emotional responses to potentially threatening stimuli. The concept of anxiety disorders as a disturbance of emotional response regulation is a useful one as it allows anxiety to be explained in terms of a more general model of aberrant salience and also because it identifies avenues for developing psychological, behavioral, and pharmacological strategies for the treatment of anxiety disorder. These circuits involve bottom-up activity from the amygdala, indicating the presence of potentially threatening stimuli, and top-down control mechanisms originating in the prefrontal cortex, signaling the emotional salience of stimuli. Understanding the factors that control cortical mechanisms may open the way to identification of more effective cognitive behavioral strategies for managing anxiety disorders. The brain circuits in the amygdala are thought to comprise inhibitory networks of Υ-aminobutyric acid-ergic (GABAergic interneurons and this neurotransmitter thus plays a key role in the modulation of anxiety responses both in the normal and pathological state. The presence of allosteric sites on the GABAA receptor allows the level of inhibition of neurons in the amygdala to be regulated with exquisite precision, and these sites are the molecular targets of the principal classes of anxiolytic drugs. Changes in the levels of endogenous modulators of these allosteric sites as well as changes in the subunit composition of the GABAA receptor may represent mechanisms whereby the level of neuronal inhibition is downregulated in pathological anxiety states. Neurosteroids are synthesized in the brain and

  12. Endogenous retinoic acid activity in principal cells and intercalated cells of mouse collecting duct system.

    Directory of Open Access Journals (Sweden)

    Yuen Fei Wong


    Full Text Available Retinoic acid is the bioactive derivative of vitamin A, which plays an indispensible role in kidney development by activating retinoic acid receptors. Although the location, concentration and roles of endogenous retinoic acid in post-natal kidneys are poorly defined, there is accumulating evidence linking post-natal vitamin A deficiency to impaired renal concentrating and acidifying capacity associated with increased susceptibility to urolithiasis, renal inflammation and scarring. The aim of this study is to examine the presence and the detailed localization of endogenous retinoic acid activity in neonatal, young and adult mouse kidneys, to establish a fundamental ground for further research into potential target genes, as well as physiological and pathophysiological roles of endogenous retinoic acid in the post-natal kidneys.RARE-hsp68-lacZ transgenic mice were employed as a reporter for endogenous retinoic acid activity that was determined by X-gal assay and immunostaining of the reporter gene product, β-galactosidase. Double immunostaining was performed for β-galactosidase and markers of kidney tubules to localize retinoic acid activity. Distinct pattern of retinoic acid activity was observed in kidneys, which is higher in neonatal and 1- to 3-week-old mice than that in 5- and 8-week-old mice. The activity was present specifically in the principal cells and the intercalated cells of the collecting duct system in all age groups, but was absent from the glomeruli, proximal tubules, thin limbs of Henle's loop and distal tubules.Endogenous retinoic acid activity exists in principal cells and intercalated cells of the mouse collecting duct system after birth and persists into adulthood. This observation provides novel insights into potential roles for endogenous retinoic acid beyond nephrogenesis and warrants further studies to investigate target genes and functions of endogenous retinoic acid in the kidney after birth, particularly in the

  13. mRNA and Protein Levels for GABA[subscript A][alpha]4, [alpha]5, [beta]1 and GABA[subscript B]R1 Receptors are Altered in Brains from Subjects with Autism (United States)

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rooney, Robert J.; Patel, Diven H.; Thuras, Paul D.


    We have shown altered expression of gamma-aminobutyric acid A (GABA[subscript A]) and gamma-aminobutyric acid B (GABA[subscript B]) receptors in the brains of subjects with autism. In the current study, we sought to verify our western blotting data for GABBR1 via qRT-PCR and to expand our previous work to measure mRNA and protein levels of 3…

  14. Chronic prenatal ethanol exposure alters hippocampal GABA(A) receptors and impairs spatial learning in the guinea pig. (United States)

    Iqbal, U; Dringenberg, H C; Brien, J F; Reynolds, J N


    Chronic prenatal ethanol exposure (CPEE) can injure the developing brain, and may lead to the fetal alcohol syndrome (FAS). Previous studies have demonstrated that CPEE upregulates gamma-aminobutyric acid type A (GABA(A)) receptor expression in the cerebral cortex, and decreases functional synaptic plasticity in the hippocampus, in the adult guinea pig. This study tested the hypothesis that CPEE increases GABA(A) receptor expression in the hippocampus of guinea pig offspring that exhibit cognitive deficits in a hippocampal-dependent spatial learning task. Timed, pregnant guinea pigs were treated with ethanol (4 g/kg maternal body weight per day), isocaloric-sucrose/pair-feeding, or water throughout gestation. GABA(A) receptor subunit protein expression in the hippocampus was measured at two development ages: near-term fetus and young adult. In young adult guinea pig offspring, CPEE increased spontaneous locomotor activity in the open-field and impaired task acquisition in the Morris water maze. CPEE did not change GABA(A) receptor subunit protein expression in the near-term fetal hippocampus, but increased expression of the beta2/3-subunit of the GABA(A) receptor in the hippocampus of young adult offspring. CPEE did not change either [(3)H]flunitrazepam binding or GABA potentiation of [(3)H]flunitrazepam binding, but decreased the efficacy of allopregnanolone potentiation of [(3)H]flunitrazepam binding, to hippocampal GABA(A) receptors in adult offspring. Correlational analysis revealed a relationship between increased spontaneous locomotor activity and growth restriction in the hippocampus induced by CPEE. Similarly, an inverse relationship was found between performance in the water maze and the efficacy of allopregnanolone potentiation of [(3)H]flunitrazepam binding in the hippocampus. These data suggest that alterations in hippocampal GABA(A) receptor expression and pharmacological properties contribute to hippocampal-related behavioral and cognitive deficits

  15. VPAC1 and VPAC2 receptor activation on GABA release from hippocampal nerve terminals involve several different signalling pathways. (United States)

    Cunha-Reis, Diana; Ribeiro, Joaquim Alexandre; de Almeida, Rodrigo F M; Sebastião, Ana M


    Vasoactive intestinal peptide (VIP) is an important modulator of hippocampal synaptic transmission that influences both GABAergic synaptic transmission and glutamatergic cell excitability through activation of VPAC1 and VPAC2 receptors. Presynaptic enhancement of GABA release contributes to VIP modulation of hippocampal synaptic transmission. We investigated which VIP receptors and coupled transduction pathways were involved in VIP enhancement of K+ -evoked [3 H]-GABA release from isolated nerve terminals of rat hippocampus. VIP enhancement of [3 H]-GABA release was potentiated in the presence of the VPAC1 receptor antagonist PG 97-269 but converted into an inhibition in the presence of the VPAC2 receptor antagonist PG 99-465, suggesting that activation of VPAC1 receptors inhibits and activation of VPAC2 receptors enhances, GABA release. A VPAC1 receptor agonist inhibited exocytotic voltage-gated calcium channel (VGCC)-dependent [3 H]-GABA release through activation of protein Gi/o , an effect also dependent on PKC activity. A VPAC2 receptor agonist enhanced both exocytotic VGCC-dependent release through protein Gs -dependent, PKA-dependent and PKC-dependent mechanisms and GABA transporter 1-mediated [3 H]-GABA release through a Gs protein-dependent and PKC-dependent mechanism. Our results show that VPAC1 and VPAC2 VIP receptors have opposing actions on GABA release from hippocampal nerve terminals through activation of different transduction pathways. As VPAC1 and VPAC2 receptors are located in different layers of Ammon's horn, our results suggest that these VIP receptors underlie different modulation of synaptic transmission to pyramidal cell dendrites and cell bodies, with important consequences for their possible therapeutic application in the treatment of epilepsy. © 2017 The British Pharmacological Society.

  16. Effects of Vigabatrin, an Irreversible GABA Transaminase Inhibitor, on Ethanol Reinforcement and Ethanol Discriminative Stimuli in Mice


    Griffin, William C.; Nguyen, Shaun A.; Deleon, Christopher P.; Middaugh, Lawrence D


    We tested the hypothesis that the irreversible gamma-amino butyric acid (GABA) transaminase inhibitor, γ-vinyl GABA (Vigabatrin; VGB) would reduce ethanol reinforcement and enhance the discriminative stimulus effect of ethanol, effectively reducing ethanol intake. The present studies used adult C57BL/6J (B6) mice in well-established operant, two-bottle choice consumption, locomotor activity and ethanol discrimination procedures, to examine comprehensively the effects of VGB on ethanol-support...

  17. Differential modulation of nicotine-induced gemcitabine resistance by GABA receptor agonists in pancreatic cancer cell xenografts and in vitro


    Banerjee, Jheelam; Al-Wadei, Hussein AN; Al-Wadei, Mohammed H.; Dagnon, Koami; Schuller, Hildegard M.


    Background Pancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicot...

  18. GABA and glutamate pathways are spatially and developmentally affected in the brain of Mecp2-deficient mice.

    Directory of Open Access Journals (Sweden)

    Rita El-Khoury

    Full Text Available Proper brain functioning requires a fine-tuning between excitatory and inhibitory neurotransmission, a balance maintained through the regulation and release of glutamate and GABA. Rett syndrome (RTT is a rare genetic disorder caused by mutations in the methyl-CpG binding protein 2 (MECP2 gene affecting the postnatal brain development. Dysfunctions in the GABAergic and glutamatergic systems have been implicated in the neuropathology of RTT and a disruption of the balance between excitation and inhibition, together with a perturbation of the electrophysiological properties of GABA and glutamate neurons, were reported in the brain of the Mecp2-deficient mouse. However, to date, the extent and the nature of the GABA/glutamate deficit affecting the Mecp2-deficient mouse brain are unclear. In order to better characterize these deficits, we simultaneously analyzed the GABA and glutamate levels in Mecp2-deficient mice at 2 different ages (P35 and P55 and in several brain areas. We used a multilevel approach including the quantification of GABA and glutamate levels, as well as the quantification of the mRNA and protein expression levels of key genes involved in the GABAergic and glutamatergic pathways. Our results show that Mecp2-deficient mice displayed regional- and age-dependent variations in the GABA pathway and, to a lesser extent, in the glutamate pathway. The implication of the GABA pathway in the RTT neuropathology was further confirmed using an in vivo treatment with a GABA reuptake inhibitor that significantly improved the lifespan of Mecp2-deficient mice. Our results confirm that RTT mouse present a deficit in the GABAergic pathway and suggest that GABAergic modulators could be interesting therapeutic agents for this severe neurological disorder.

  19. Kinetics of circulating endogenous insulin, C-peptide, and proinsulin in fasting nondiabetic man

    DEFF Research Database (Denmark)

    Henriksen, J H; Tronier, B; Bülow, J B


    Plasma concentrations of insulin, C-peptide, and proinsulin were measured in different vascular beds in order to determine renal, hepatic, and systemic kinetics of the endogenous peptides in the fasting condition. Nineteen nondiabetic subjects were studied, two were normal, nine had minor vascular...

  20. Persistent Nociception Induces Anxiety-like Behavior in Rodents: Role of Endogenous Neuropeptide S (United States)

    Zhang, Shuzhuo; Jin, Xu; You, Zerong; Wang, Shuxing; Lim, Grewo; Yang, Jinsheng; McCabe, Michael; Li, Na; Marota, John; Chen, Lucy; Mao, Jianren


    Anxiety disorder is a comorbid condition of chronic pain. Analgesics and anxiolytics, subject to addiction and abuse, are currently used to manage pain and anxiety symptoms. However, the cellular mechanism underlying chronic pain and anxiety interaction remains to be elucidated. We report that persistent nociception following peripheral nerve injury induced anxiety-like behavior in rodents. Brain expression and release of neuropeptide S (NPS), a proposed endogenous anxiolytic peptide, was diminished in rodents with co-existing nociceptive and anxiety-like behaviors. Intracerebroventricular administration of exogenous NPS concurrently improved both nociceptive and anxiety-like behaviors. At the cellular level, NPS enhanced intra-amygdaloidal inhibitory transmission by increasing presynaptic GABA release from interneurons. These findings indicate that the interaction between nociceptive and anxiety-like behaviors in rodents may be regulated by the altered NPS-mediated intra-amygdaloidal GABAergic inhibition. The data suggest that enhancing the brain NPS function may be a new strategy to manage comorbid pain and anxiety. PMID:24793908

  1. Evidence for a role of GABA- and glutamate-gated chloride channels in olfactory memory. (United States)

    Boumghar, Katia; Couret-Fauvel, Thomas; Garcia, Mikael; Armengaud, Catherine


    In the honeybee, we investigated the role of transmissions mediated by GABA-gated chloride channels and glutamate-gated chloride channels (GluCls) of the mushroom bodies (MBs) on olfactory learning using a single-trial olfactory conditioning paradigm. The GABAergic antagonist picrotoxin (PTX) or the GluCl antagonist L-trans-pyrrolidine-2,4-dicarboxylic acid (L-trans-PDC) was injected alone or in combination into the α-lobes of MBs. PTX impaired early long-term olfactory memory when injected before conditioning or before testing. L-trans-PDC alone induced no significant effect on learning and memory but induced a less specific response to the conditioned odor. When injected before PTX, L-trans-PDC was able to modulate PTX effects. These results emphasize the role of MB GABA-gated chloride channels in consolidation processes and strongly support that GluCls are involved in the perception of the conditioned stimulus.

  2. Expression of the GABA(A) receptor alpha6 subunit in cultured cerebellar granule cells is developmentally regulated by activation of GABA(A) receptors

    DEFF Research Database (Denmark)

    Carlson, B X; Belhage, B; Hansen, Gert Helge


    Primary cultures of cerebellar granule cells, prepared from cerebella of 7-day-old rats and cultured for 4 or 8 days, were used to study the neurodifferentiative effect of a GABA(A) receptor agonist, 4,5,6,7-tetrahydroisoxazol[5,4-c]pyridin-3-ol (THIP), on the expression of the alpha6 GABA......Da (alpha6 subunit) radioactive peaks in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In contrast, THIP-treated granule cells at 8 DIV demonstrated a small but significant decrease from control cultures in the photoincorporation of [3H]Ro15-4513 in the 51-kDa peak; however......, no significant change in [3H]Ro15-4513 binding was observed for the 56-kDa polypeptide. Immunolabeling of the alpha6 subunit using silver-enhanced, immuno-gold staining of granule cells showed a significant effect with THIP treatment only at 4 DIV and not at 8 DIV. Examination by light microscopy demonstrated...

  3. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA


    Mariia Nesterkina; Iryna Kravchenko


    Novel esters of ?-aminobutyric acid (GABA) with monocyclic terpenes were synthesized via Steglich esterification and characterized by 1H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate ac...

  4. Motor dysfunction in cerebellar Purkinje cell-specific vesicular GABA transporter knockout mice

    Directory of Open Access Journals (Sweden)

    Mikiko eKayakabe


    Full Text Available γ-Aminobutyric acid (GABA is a major inhibitory neurotransmitter in the adult mammalian central nervous system and plays modulatory roles in neural development. The vesicular GABA transporter (VGAT is an essential molecule for GABAergic neurotransmission due to its role in vesicular GABA release. Cerebellar Purkinje cells (PCs are GABAergic projection neurons that are indispensable for cerebellar function. To elucidate the significance of VGAT in cerebellar PCs, we generated and characterized PC-specific VGAT knockout (L7-VGAT mice. VGAT mRNAs and proteins were specifically absent in the 40-week-old L7-VGAT PCs. The morphological charactereistics, such as lamination and foliation of the cerebellar cortex, of the L7-VGAT mice were similar to those of the control littermate mice. Moreover, the protein expression levels and patterns of pre- (calbindin and parvalbumin and postsynaptic (GABA-A receptor α1 subunit (GABAARα1 and gephyrin molecules between the L7-VGAT and control mice were similar in the deep cerebellar nuclei that receive PC projections. However, the L7-VGAT mice performed poorly in the accelerating rotarod test and displayed ataxic gait in the footprint test. The L7-VGAT mice also exhibited severer ataxia as VGAT deficits progressed. These results suggest that VGAT in cerebellar Purkinje cells is not essential for the rough maintenance of cerebellar structure, but does play an important role in motor coordination. The L7-VGAT mice are a novel model of ataxia without PC degeneration, and would also be useful for studying the role of Purkinje cells in cognition and emotion.

  5. The role of the GABA(B) receptor and calcium channels in a Drosophila model of Parkinson's Disease. (United States)

    Hillman, Ralph; Sinani, Jonida; Pendleton, Robert


    Transgenic Drosophila melanogaster carrying the human gene for alpha synuclein is an animal model for the study of Parkinson's Disease. Climbing activity in these flies is reduced as a result of the effect of this protein on the locomotor activity of the transgenic fly. L-DOPA and gamma amino butyric acid (GABA) reverse the loss of this activity when placed in the food fed to these flies. While muscimol, a GABA(A) receptor agonist has no effect in this system, baclofen and the allosteric agonists CG 7930 and GS 39783 which affect the GABA(B) receptor reverse this activity. This latter effect is eliminated when these compounds are fed in conjunction with the GABA(B) receptor antagonist 2-hydroxysaclofen. In addition, fendiline which is a Ca(++) receptor blocker also reverses the loss of climbing ability. Because there is a calcium channel close to the GABA(B) receptor on the cell surface, these data are indicative of a relationship between the roles of the GABA(B) receptor, the calcium channel and the effect of alpha-synuclein on the motor activity of the transgenic fly. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Cardiovascular and behavioral effects produced by administration of liposome-entrapped GABA into the rat central nervous system. (United States)

    Vaz, G C; Bahia, A P C O; de Figueiredo Müller-Ribeiro, F C; Xavier, C H; Patel, K P; Santos, R A S; Moreira, F A; Frézard, F; Fontes, M A P


    Liposomes are nanosystems that allow a sustained release of entrapped substances. Gamma-aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter of the central nervous system (CNS). We developed a liposomal formulation of GABA for application in long-term CNS functional studies. Two days after liposome-entrapped GABA was injected intracerebroventricularly (ICV), Wistar rats were submitted to the following evaluations: (1) changes in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) to ICV injection of bicuculline methiodide (BMI) in anesthetized rats; (2) changes in cardiovascular reactivity to air jet stress in conscious rats; and (3) anxiety-like behavior in conscious rats. GABA and saline-containing pegylated liposomes were prepared with a mean diameter of 200 nm. Rats with implanted cannulas targeted to lateral cerebral ventricle (n = 5-8/group) received either GABA solution (GS), empty liposomes (EL) or GABA-containing liposomes (GL). Following (48 h) central microinjection (2 μL, 0.09 M and 99 g/L) of liposomes, animals were submitted to the different protocols. Animals that received GL demonstrated attenuated response of RSNA to BMI microinjection (GS 48 ± 9, EL 43 ± 9, GL 11 ± 8%; P nervous system. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  7. Neonatal maternal separation delays the GABA excitatory-to-inhibitory functional switch by inhibiting KCC2 expression. (United States)

    Furukawa, Minami; Tsukahara, Takao; Tomita, Kazuo; Iwai, Haruki; Sonomura, Takahiro; Miyawaki, Shouichi; Sato, Tomoaki


    The excitatory-to-inhibitory functional switch of γ-aminobutyric acid (GABA; GABA switch), which normally occurs in the first to the second postnatal week in the hippocampus, is necessary for the development of appropriate central nervous system function. A deficit in GABAergic inhibitory function could cause excitatory/inhibitory (E/I) neuron imbalance that is found in many neurodegenerative disorders. In the present study, we examined whether neonatal stress can affect the timing of the GABA functional switch and cause disorders during adolescence. Neonatal stress was induced in C57BL/6J male mouse pups by maternal separation (MS) on postnatal days (PND) 1-21. Histological quantification of K+-Cl- co-transporter (KCC2) and Ca2+ imaging were performed to examine the timing of the GABA switch during the MS period. To evaluate the influence of neonatal MS on adolescent hippocampal function, we quantified KCC2 expression and evaluated hippocampal-related behavioral tasks at PND35-38. We showed that MS delayed the timing of the GABA switch in the hippocampus and inhibited the increase in membrane KCC2 expression, with KCC2 expression inhibition persisting until adolescence. Behavioral tests showed impaired cognition, declined attention, hyperlocomotion, and aggressive character in maternally separated mice. Taken together, our results show that neonatal stress delayed the timing of the GABA switch, which could change the E/I balance and cause neurodegenerative disorders in later life. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Interplay between the transcription factors acting on the GATA- and GABA-responsive elements of Saccharomyces cerevisiae UGA promoters. (United States)

    Cardillo, Sabrina B; Levi, Carolina E; Bermúdez Moretti, Mariana; Correa García, Susana


    γ-Aminobutyric acid (GABA) transport and catabolism in Saccharomyces cerevisiae are subject to a complex transcriptional control that depends on the nutritional status of the cells. The expression of the genes that form the UGA regulon is inducible by GABA and sensitive to nitrogen catabolite repression (NCR). GABA induction of these genes is mediated by Uga3 and Dal81 transcription factors, whereas GATA factors are responsible for NCR. Here, we show how members of the UGA regulon share the activation mechanism. Our results show that both Uga3 and Dal81 interact with UGA genes in a GABA-dependent manner, and that they depend on each other for the interaction with their target promoters and the transcriptional activation. The typical DNA-binding domain Zn(II)(2)-Cys(6) of Dal81 is unnecessary for its activity and Uga3 acts as a bridge between Dal81 and DNA. Both the trans-activation activity of the GATA factor Gln3 and the repressive activity of the GATA factor Dal80 are exerted by their interaction with UGA promoters in response to GABA, indicating that Uga3, Dal81, Gln3 and Dal80 all act in concert to induce the expression of UGA genes. So, an interplay between the factors responsible for GABA induction and those responsible for NCR in the regulation of the UGA genes is proposed here.

  9. Imitation of biomembranes on the basis of cholic acid and endogenic thermostable protein complex in biopartitioning micellar chromatography. (United States)

    Rukhadze, Marina; Dzidziguri, Diana; Giorgobiani, Nana; Kerkenjia, Salome


    The structure of biomembranes was imitated by introducing nonionic surfactant polyoxyethylene (23) dodecylether, cholic acid and endogenic thermostable protein complex (14-65 kDa) into the mobile phase. The influence of concentration of these additives on the retention of the model compounds was studied. The competing interaction of cholic acid and endogenic thermostable protein complex in the lipid bilayer model was revealed on the basis of chromatographic data. The values of efficiency of the chromatographic column regarding solutes were increased by addition of endogenic thermostable protein complex to the mobile phase containing Brij-35 and cholic acid. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Interactions of pyrethroid insecticides with GABA sub A and peripheral-type benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Devaud, L.L.


    Pyrethroid insecticides are potent proconvulsants in the rat. All pyrethroids evincing proconvulsant activity elicited a similar 25-30% maximal reduction of seizure threshold. The Type II pyrethroids were the most potent proconvulsants with 1R{alpha}S, cis cypermethrin having an ED{sub 50} value of 6.3 nmol/kg. The proconvulsant activity of both Type I and Type II pyrenthroids was blocked by pretreatment with PK 11195, the peripheral-type benzodiazepine receptor (PTBR) antagonist. In contrast, phenytoin did not antagonize the proconvulsant activity of either deltamethrin or permethrin. Pyrethroids displaced the specific binding of ({sup 3}H)Ro5-4864 to rat brain membranes with a significant correlation between the log EC{sub 50} values for their activities as proconvulsants and the log IC{sub 50} values for their inhibition of ({sup 3}H)Ro5-4864 binding. Both Ro5-4864 and pyrethroid insecticides were found to influence specific ({sup 35}S)TBPS binding in a GABA-dependent manner. PK 11195 and the Type II pyrethroid, deltamethrin antagonized the Ro5-4864-induced modulation of ({sup 35}S)TBPS binding. Pyrethroid insecticides, Ro5-4864 and veratridine influenced GABA-gated {sup 36}Chloride influx. Moreover, the Type II pyrethroids elicited an increase in {sup 36}chloride influx in the absence of GABA-stimulation. Both of these actions were antagonized by PK 11195 and tetrodotoxin.

  11. Role of brain regional GABA: aldrin-induced stimulation of locomotor activity in rat. (United States)

    Jamaluddin, S K; Poddar, M K


    Aldrin, a chlorinated hydrocarbon group of pesticide, is a well known central nervous system (CNS) stimulant. The CNS stimulating effect of aldrin is manifested in the form of an increase in locomotor activity (LA) of animals. Maximum increase in LA was observed at 2 h following aldrin (2-10 mg/kg, p.o.) treatment and this aldrin-induced increase in LA attained a peak at a dose of 10 mg/kg, p.o. Administration of aldrin (2 or 5 mg/kg/day, p.o.) enhanced LA of rats and reached a maxima after 12 consecutive days of treatment following which aldrin-induced LA was gradually reduced and restored to control value after 20 consecutive days of aldrin treatment. A single administration of aldrin (2-10 mg/kg, p.o.) reduced the GABA system in cerebellum, hypothalamus and pons-medulla. The treatment with aldrin (2 mg/kg/day, p.o.) for 12 consecutive days produced more inhibition in those brain regional GABA system than that observed with a single dose of aldrin. These results, thus, suggest that aldrin-induced inhibition of central GABA may be a cause of stimulation of LA with aldrin either at a single dose or for 12 consecutive days.

  12. Medications acting on the GABA system in the treatment of alcoholic patients. (United States)

    Caputo, Fabio; Bernardi, Mauro


    Gamma aminobutyric acid (GABA) represents the major inhibitory neurotransmitter of the central nervous system. Ethanol as well as benzodiazepines (BDZs) and some anticonvulsant drugs directly affect GABAA receptors inducing similar anxiolytic, sedativehypnotic, and anticonvulsant effects. Since BDZs have proven their efficacy in ameliorating symptoms and in decreasing the risk of seizures and delirium tremens, they are the drugs of choice for the treatment of alcohol withdrawal syndrome (AWS). However, due to their addictive potential and lack of safety when combined with alcohol, BDZs are usually not recommended for the maintenance of alcohol abstinence. Other GABA-ergic medications represent potentially promising drugs useful in the treatment of AWS and in maintaining alcohol abstinence. Indeed, available studies have demonstrated that clomethiazole, gabapentin and gamma hydroxybutyrate (GHB) present a similar efficacy to BDZs in suppressing AWS. In addition, current evidence also indicates that gabapentin and GHB do not have significant interactions with ethanol that render them safe to use in maintaining alcohol abstinence. Moreover, gabapentin and valproic acid may be beneficial in maintaining alcohol abstinence in alcoholics with psychiatric co-morbidity. Pregabalin, neurosteroids, tiagabine, and vigabatrin need further clinical evidence of efficacy, safety and tolerability. Thus, given the importance of GABA-ergic mechanisms in the development and maintenance of alcohol dependence, and the very interesting results currently achieved, more research on GABAergic agents is warranted.

  13. GABA, taurine and learning: release of amino acids from slices of chick brain following filial imprinting. (United States)

    McCabe, B J; Horn, G; Kendrick, K M


    The intermediate and medial hyperstriatum ventrale (IMHV) is a forebrain region in the domestic chick that is a site of information storage for the learning process of imprinting. We enquired whether imprinting is associated with learning-related increases in calcium-dependent, potassium-stimulated release of neurotransmitter amino acids from the IMHV. Chicks were hatched and reared in darkness until 15-30 h after hatching. They then either remained in darkness or were trained for 2 h by exposure to an imprinting stimulus. One hour later, the chicks were given a preference test and a preference score was calculated from the results of this test, as a measure of imprinting. Chicks were killed 2 h after training. Slices from the left and right IMHV of trained and untrained chicks were superfused with Krebs' solution either with or without calcium and the superfusate assayed for arginine, aspartate, citrulline, GABA, glutamate, glycine and taurine using high-performance liquid chromatography. For calcium-containing superfusates from the left IMHV, preference score was significantly correlated with potassium-stimulated release of (i) GABA (r=0.51, 23 d.f., P=0.008) and (ii) taurine (r=0.77, 23 d.f., Pimprinting is associated with increases in releasable pools of GABA and taurine and/or membrane excitability in the left IMHV.

  14. CXCL12 chemokine and GABA neurotransmitter systems crosstalk and their putative roles

    Directory of Open Access Journals (Sweden)

    Guyon eAlice


    Full Text Available Since CXCL12 and its receptors, CXCR4 and CXCR7, have been found in the brain, the role of this chemokine has been expanded from chemoattractant in the immune system to neuromodulatory in the brain. Several pieces of evidence suggest that this chemokine system could crosstalk with the GABAergic system, known to be the main inhibitory neurotransmitter system in the brain. Indeed, GABA and CXCL12 as well as their receptors are colocalized in many cell types including neurons and there are several examples in which these two systems interact. Several mechanisms can be proposed to explain how these systems interact, including receptor-receptor interactions, crosstalk at the level of second messenger cascades, or direct pharmacological interactions, as GABA and GABAB receptor agonists/antagonists have been shown to be allosteric modulators of CXCR4.The interplay between CXCL12/CXCR4-CXCR7 and GABA/GABAA-GABAB receptors systems could have many physiological implications in neurotransmission, cancer and inflammation. In addition, the GABAB agonist baclofen is currently used in medicine to treat spasticity in patients with spinal cord injury, cerebral palsy, traumatic brain injury, multiple sclerosis and other disorders. More recently it has also been used in the treatment of alcohol dependence and withdrawal. The allosteric effects of this agent on CXCR4 could contribute to these beneficial effects or at the opposite, to its side effects.

  15. GABA and glutamate uptake and metabolism in retinal glial (Müller cells

    Directory of Open Access Journals (Sweden)

    Andreas eBringmann


    Full Text Available Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and -aminobutyric acid (GABA. Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the shaping and termination of the synaptic activity, particularly in the inner retina. Reactive Müller cells are neuroprotective, e.g., by the clearance of excess extracellular glutamate, but may also contribute to neuronal degeneration by a malfunctioning or even reversal of glial glutamate transporters, or by a downregulation of the key enzyme, glutamine synthetase. This review summarizes the present knowledge about the role of Müller cells in the clearance and metabolization of extracellular glutamate and GABA. Some major pathways of GABA and glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism.

  16. Emotion and mood adaptations in the peripartum female:complementary contributions of GABA and oxytocin. (United States)

    Lonstein, J S; Maguire, J; Meinlschmidt, G; Neumann, I D


    Peripartum hormones and sensory cues from young modify the maternal brain in ways that can render females either at risk for, or resilient to, elevated anxiety and depression. The neurochemical systems underlying these aspects of maternal emotional and mood states include the inhibitory neurotransmitter GABA and the neuropeptide oxytocin (OXT). Data from laboratory rodents indicate that increased activity at the GABA(A) receptor contributes to the postpartum suppression of anxiety-related behaviour that is mediated by physical contact with offspring, whereas dysregulation in GABAergic signalling results in deficits in maternal care, as well as anxiety- and depression-like behaviours during the postpartum period. Similarly, activation of the brain OXT system accompanied by increased OXT release within numerous brain sites in response to reproductive stimuli also reduces postpartum anxiety- and depression-like behaviours. Studies of peripartum women are consistent with these findings in rodents. Given the similar consequences of elevated central GABA and OXT activity on maternal anxiety and depression, balanced and partly reciprocal interactions between these two systems may be essential for their effects on maternal emotional and mood states, in addition to other aspects of postpartum behaviour and physiology. © 2014 British Society for Neuroendocrinology.

  17. Microcystin-LR induces changes in the GABA neurotransmitter system of zebrafish. (United States)

    Yan, Wei; Li, Li; Li, Guangyu; Zhao, Sujuan


    It has been reported that exposure to microcystins altered adult zebrafish swimming performance parameters, but the possible mechanisms of action remain unknown. Neuronal activity depends on the balance between the number of excitatory and inhibitory processes which are associated with neurotransmitters. In the present study, zebrafish embryos (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30μg/L (microcystin-LR) MCLR for 90day until reaching sexual maturity. To investigate the effects of MCLR on the neurotransmitter system, mRNA levels involved in amino acid g-aminobutyric acid (GABA) and glutamate metabolic pathways were tested using quantitative real-time PCR. Significant increase of GABAA receptor, alpha 1 (gabra1), glutamate decarboxylase (gad1b), glutaminase (glsa) and reduction of mRNA expression of GABA transporter (gat1) at transcriptional level were observed in the brain. Meanwhile, western blotting showed that the protein levels of gabra1, gad1b were induced by MCLR, whereas the expression of gat1 was decreased. In addition, MCLR induced severe damage to cerebrum ultrastructure, showing edematous and collapsed myelinated nerve fibers, distention of endoplasmic reticulum and swelling mitochondria. Our results suggested that MCLR showed neurotoxicity in zebrafish which might attribute to the disorder of GABA neurotransmitter pathway. Copyright © 2017. Published by Elsevier B.V.

  18. Amphetamine and antidepressant drug effects on GABA- and NMDA-related seizures. (United States)

    Borowski, T B; Kirkby, R D; Kokkinidis, L


    Research has shown a synergistic relationship between amphetamine sensitization and limbic system kindling. To explore the role of GABA and NMDA receptor activity in modulating the positive effects of amphetamine on epileptogenesis, alterations in GABA- and NMDA-related convulsions were examined after acute and chronic amphetamine administration. A single injection of d-amphetamine (7.5 mg/kg) significantly decreased latencies to generalized motor seizures induced 12 h later by the noncompetitive GABAA receptor antagonist picrotoxin (10 mg/kg). The increased sensitivity to clonus was specific to acute amphetamine treatment and was not evident following withdrawal from chronic drug exposure. Seizures induced by NMDLA (1,000 mg/kg), on the other hand, were not modified by acute amphetamine injection; however, the latency to clonus was reduced substantially after NMDLA injection to mice chronically preexposed to amphetamine. The short- and long-term amphetamine effects on GABA- and NMDA-associated convulsive activity were not paralleled by similar drug treatment schedules involving acute (20 mg/kg) and chronic administration of desipramine, zimelidine, and buproprion. These results suggest that amphetamine may be acting on inhibitory and excitatory amino acid systems independently of its monoaminergic properties. The implications of these findings were discussed in relation to amphetamine sensitization of mesolimbic functioning.

  19. Lateral Preoptic Control of the Lateral Habenula through Convergent Glutamate and GABA Transmission

    Directory of Open Access Journals (Sweden)

    David J. Barker


    Full Text Available The lateral habenula (LHb is a brain structure that participates in cognitive and emotional processing and has been implicated in several mental disorders. Although one of the largest inputs to the LHb originates in the lateral preoptic area (LPO, little is known about how the LPO participates in the regulation of LHb function. Here, we provide evidence that the LPO exerts bivalent control over the LHb through the convergent transmission of LPO glutamate and γ-aminobutyric acid (GABA onto single LHb neurons. In vivo, both LPO-glutamatergic and LPO-GABAergic inputs to the LHb are activated by aversive stimuli, and their predictive cues yet produce opposing behaviors when stimulated independently. These results support a model wherein the balanced response of converging LPO-glutamate and LPO-GABA are necessary for a normal response to noxious stimuli, and an imbalance in LPO→LHb glutamate or GABA results in the type of aberrant processing that may underlie mental disorders.

  20. Benzodiazepine receptor ligand influences on learning: an endogenous modulatory mechanism mediated by benzodiazepines possibly of alimentary origin

    Directory of Open Access Journals (Sweden)

    I. Izquierdo


    Full Text Available In rats pre-but not post-training ip administration of either flumazenil, a central benzodiazepine (BSD receptor antagonist, or of n-butyl-B-carboline-carboxylate (BCCB, an inverse agonist, enhanced retention of inhibitory avoidance learning. Flumazenil vlocked the enhancing effect of BCCB, and the inhibitory effect of the BZD agonists clonazepam and diazepam also given pre-training. Post-training administration of these drugs had no effects. The peripheral BZD receptor agonist/chloride channel blocker Ro5-4864 had no effect on the inhibitory avoidance task when given ip prior to training, buth it caused enhancement when given immediately post-training either ip or icv. This effect was blocked by PK11195, a competitive antagonist of Ro5-4864. These results suggest that ther is an endogenous mechanism mediated by BZD agonists, which is sensitive to inverse agonists and that normally down-regulates the formation of memories through a mechanism involving GABA-A receptors and the corresponding chloride channels. The most likely agonists for the endogenous mechanism suggested are the diazepam-like BZDs found in brain whose origin is possibly alimentary. Levels of these BZDs in the cortex were found to sharply decrease after inhibitory acoidance training or mere exposure to the training apparatus.

  1. Endogenous Market Structures and Labor Market Dynamics


    Colciago, Andrea; Rossi, Lorenza


    We propose a model characterized by strategic interactions among an endogenous number of producers and search and matching frictions in the labor market. In line with U.S. data: (i) new firms account for a relatively small share of overall employment, but they create a relevant fraction of new jobs; (ii) firms’ entry is procyclical; (iii) price mark ups are countercyclical, while aggregate profits are procyclical. In response to a technology shock the labor share decreases on impact and overs...

  2. Unfunded pensions and endogenous labor supply

    DEFF Research Database (Denmark)

    Andersen, Torben M.; Bhattacharya, Joydeep

    A classic result in dynamic public economics, dating back to Aaron (1966) and Samuelson (1975), states that there is no welfare rationale for PAYG pensions in a dynamically-efficient neoclassical economy with exogenous labor supply. This paper argues that this result, under the fairly......-mild restriction that the old be no less risk-averse than the young, extends to a neoclassical economy with endogenous labor supply....

  3. Public Procurement of Innovation as Endogenous

    DEFF Research Database (Denmark)

    Rolfstam, Max

    Public procurement used as an innovation policy instrument has attracted attention the last decade. It has been argued that public procurement can be used to stimulate innovation from the demand-side. This paper problematizes ‘demand’ understood as a problem defined by a public procurer given...... underlying mechanisms critical for success. Instead the paper views public procurement of innovation as an instrument of endogenous- exogenous knowledge conversion....

  4. Unionised labour market, environment and endogenous growth


    Bhattacharyya, Chandril; Gupta, Manash Ranjan


    In this paper, a model of endogenous economic growth is developed with special focus on the interaction between unionized labour market and environmental pollution. We introduce a trade union; and use both ‘Efficient Bargaining’ model and ‘Right to Manage’ model to solve the negotiation problem. Environmental pollution is the result of production; and the labour union bargains not only for wage and employment but also for the protection of environment. We derive properties of optimum income t...

  5. Neoclassical vs. Endogenous Growth Analysis: An Overview


    Bennett T. McCallum


    This paper begins with an exposition of neoclassical growth theory, including several analytical results such as the distinction between golden-rule and optimal steady states. Next it emphasizes that the neoclassical approach fails to provide any explanation of steady-state growth in per capita values of output and consumption, and also cannot plausibly explain actual growth differences by reference to transitional episodes. Three types of endogenous growth models, which attempt to provide ex...

  6. Buyer Search Costs and Endogenous Product Design


    Dmitri Kuksov


    Buyer search costs for price are changing in many markets. Through a model of buyer and seller behavior, I consider the effects of changing search costs on prices both when product differentiation is fixed and when it is endogenously determined in equilibrium. If firms cannot change product design, lower buyer search costs for price lead to increased price competition. However, if product design is a decision variable, lower search costs for price may also lead to higher product differentiati...

  7. Prices vs. Quantities with Endogenous Cost Structure


    Storrøsten, Halvor Briseid


    Authorities often lack information for efficient regulation of the commons. This paper derives a criterion comparing prices versus tradable quantities in terms of expected welfare, given uncertainty, optimal policy and endogenous cost structure. I show that one cannot determine which regulatory instrument that induces the highest expected welfare based on the relative curvatures of the cost and benefit functions alone. Furthermore, optimal policy involves different production (or price) targe...

  8. Asset Bubbles, Endogenous Growth, and Financial Frictions


    Hirano, Tomohiro; Yanagawa, Noriyuki


    This paper analyzes the effects of bubbles in an infinitely-lived agent model of endogenous growth with financial frictions and heterogeneous agents. We provide a complete characterization on the relationship between financial frictions and the existence of bubbles. Our model predicts that if the degree of pledgeability is sufficiently high or sufficiently low, bubbles can not exist. They can only arise at an intermediate degree. This suggests that improving the financial market condition mig...

  9. Endogenous endophthalmitis after severe burn: A case report

    Directory of Open Access Journals (Sweden)

    Seyedeh Maryam Hosseini


    Conclusion: Burn patients treated with broad-spectrum antibiotics are at risk of candidemia and its complications, including endogenous endophthalmitis. Early diagnosis of endogenous endophthalmitis in high risk patients could prevent visual loss.

  10. Endogenous Generalized Weights under DEA Control

    DEFF Research Database (Denmark)

    Agrell, Per J.; Bogetoft, Peter

    Non-parametric efficiency analysis, such as Data Envelopment Analysis (DEA) relies so far on endogenous local or exogenous general weights, based on revealed preferences or market prices. However, as DEA is gaining popularity in regulation and normative budgeting, the strategic interest of the ev......-priced out- puts is relevant. The results show that sector wide weighting schemes favor input/output combinations that are less variable than would individual units......Non-parametric efficiency analysis, such as Data Envelopment Analysis (DEA) relies so far on endogenous local or exogenous general weights, based on revealed preferences or market prices. However, as DEA is gaining popularity in regulation and normative budgeting, the strategic interest...... of the evaluated industry calls for attention. We offer endogenous general prices based on a reformulation of DEA where the units collectively propose the set of weights that maximize their efficiency. Thus, the sector-wide efficiency is then a result of compromising the scores of more specialized smaller units...

  11. Fanconi anemia proteins and endogenous stresses

    Energy Technology Data Exchange (ETDEWEB)

    Pang Qishen [Division of Experimental Hematology and Cancer Biology, Cincinnati Children' s Research Foundation, Cincinnati, OH (United States); Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH (United States); Andreassen, Paul R., E-mail: [Division of Experimental Hematology and Cancer Biology, Cincinnati Children' s Research Foundation, Cincinnati, OH (United States); Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH (United States)


    Each of the thirteen identified Fanconi anemia (FA) genes is required for resistance to DNA interstrand crosslinking agents, such as mitomycin C, cisplatin, and melphalan. While these agents are excellent tools for understanding the function of FA proteins in DNA repair, it is uncertain whether a defect in the removal of DNA interstrand crosslinks (ICLs) is the basis for the pathophysiology of FA. For example, DNA interstrand crosslinking agents induce other types of DNA damage, in addition to ICLs. Further, other DNA-damaging agents, such as ionizing or ultraviolet radiation, activate the FA pathway, leading to monoubiquitination of FANCD2 and FANCI. Also, FA patients display congenital abnormalities, hematologic deficiencies, and a predisposition to cancer in the absence of an environmental source of ICLs that is external to cells. Here we consider potential sources of endogenous DNA damage, or endogenous stresses, to which FA proteins may respond. These include ICLs formed by products of lipid peroxidation, and other forms of oxidative DNA damage. FA proteins may also potentially respond to telomere shortening or replication stress. Defining these endogenous sources of DNA damage or stresses is critical for understanding the pathogenesis of deficiencies for FA proteins. We propose that FA proteins are centrally involved in the response to replication stress, including replication stress arising from oxidative DNA damage.

  12. Endogenous viral elements in animal genomes.

    Directory of Open Access Journals (Sweden)

    Aris Katzourakis


    Full Text Available Integration into the nuclear genome of germ line cells can lead to vertical inheritance of retroviral genes as host alleles. For other viruses, germ line integration has only rarely been documented. Nonetheless, we identified endogenous viral elements (EVEs derived from ten non-retroviral families by systematic in silico screening of animal genomes, including the first endogenous representatives of double-stranded RNA, reverse-transcribing DNA, and segmented RNA viruses, and the first endogenous DNA viruses in mammalian genomes. Phylogenetic and genomic analysis of EVEs across multiple host species revealed novel information about the origin and evolution of diverse virus groups. Furthermore, several of the elements identified here encode intact open reading frames or are expressed as mRNA. For one element in the primate lineage, we provide statistically robust evidence for exaptation. Our findings establish that genetic material derived from all known viral genome types and replication strategies can enter the animal germ line, greatly broadening the scope of paleovirological studies and indicating a more significant evolutionary role for gene flow from virus to animal genomes than has previously been recognized.

  13. Endogenous growth theory and regional development policy

    Directory of Open Access Journals (Sweden)

    Cvetanović Slobodan


    Full Text Available The numerous versions of endogenous explanations of economic growth emphasize the importance of technological change driving forces, as well as the existence of appropriate institutional arrangements. Endogenous growth theory contributes to a better understanding of various experiences with long-term growth of countries and regions. It changes the key assumptions of the Neoclassical growth theory and participates in the modern regional development physiology explanation. Based on these conclusions, the paper: a explicates the most important theoretical postulates of the theory, b explains the most important factors of economic growth in the regions in light of the Endogenous growth theory messages and c emphasizes the key determinants of regional competitiveness which in our view is conceptually between the phenomena of micro- and macro-competitiveness and represents their necessary and unique connection. First of all, micro-competitiveness is transformed into a regional competitiveness; then regional competitiveness is transformed into a macro-competitiveness. In turn, macro - influences the microeconomic competitiveness, and the circle is closed. After that, the process starts over again.

  14. Biomarkers of exposure to endogenous oxidative and aldehyde stress. (United States)

    Bruce, W Robert; Lee, Owen; Liu, Zhen; Marcon, Norman; Minkin, Salomon; O'Brien, Peter J


    We observed an unexpectedly strong association of three different endogenous aldehydes and noted that the association could be explained by multiple reactions in which oxidative stress increased the formation of endogenous aldehydes and endogenous aldehydes increased oxidative stress. These interactions make it reasonable to assess multiple exposures to endogenous oxidative and aldehyde stress with less specific measures such as advanced glycation end-products or protein carbonyls.

  15. Selection-endogenous ordered probit and dynamic ordered probit models


    Alfonso Miranda; Massimiliano Bratti


    In this presentation we define two qualitatitive response models: 1) Selection Endogenous Dummy Ordered Probit model (SED-OP); 2) a Selection Endogenous Dummy Dynamic Selection Ordered Probit model (SED- DOP). The SED-OP model is a three-equation model constituted of an endogenous dummy equation, a selection equation, and a main equation which has an ordinal response form. The main feature of the model is that the endogenous dummy enters both the selection equation and the main equation. The ...

  16. Apparent protein digestibility and recovery of endogenous nitrogen at the terminal ileum of pigs fed diets containing various soyabean products, peas or rapeseed hulls

    NARCIS (Netherlands)

    Grala, W.; Verstegen, M.W.A.; Jansman, A.J.M.; Huisman, J.; Leeuwen, P. van


    Effects of the use of three different soyabean products (soya concentrate and two different soyabean meals), peas or rapeseed hulls in the diet on the apparent ileal digestibility of CP (N x 6.25) and recovery of ileal endogenous nitrogen (N) in weanling pigs were investigated. Ileal endogenous N

  17. A unified model of the GABA(A receptor comprising agonist and benzodiazepine binding sites.

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    Rikke Bergmann

    Full Text Available We present a full-length α(1β(2γ(2 GABA receptor model optimized for agonists and benzodiazepine (BZD allosteric modulators. We propose binding hypotheses for the agonists GABA, muscimol and THIP and for the allosteric modulator diazepam (DZP. The receptor model is primarily based on the glutamate-gated chloride channel (GluCl from C. elegans and includes additional structural information from the prokaryotic ligand-gated ion channel ELIC in a few regions. Available mutational data of the binding sites are well explained by the model and the proposed ligand binding poses. We suggest a GABA binding mode similar to the binding mode of glutamate in the GluCl X-ray structure. Key interactions are predicted with residues α(1R66, β(2T202, α(1T129, β(2E155, β(2Y205 and the backbone of β(2S156. Muscimol is predicted to bind similarly, however, with minor differences rationalized with quantum mechanical energy calculations. Muscimol key interactions are predicted to be α(1R66, β(2T202, α(1T129, β(2E155, β(2Y205 and β(2F200. Furthermore, we argue that a water molecule could mediate further interactions between muscimol and the backbone of β(2S156 and β(2Y157. DZP is predicted to bind with interactions comparable to those of the agonists in the orthosteric site. The carbonyl group of DZP is predicted to interact with two threonines α(1T206 and γ(2T142, similar to the acidic moiety of GABA. The chlorine atom of DZP is placed near the important α(1H101 and the N-methyl group near α(1Y159, α(1T206, and α(1Y209. We present a binding mode of DZP in which the pending phenyl moiety of DZP is buried in the binding pocket and thus shielded from solvent exposure. Our full length GABA(A receptor is made available as Model S1.

  18. 7T Proton Magnetic Resonance Spectroscopy of Gamma-Aminobutyric Acid, Glutamate, and Glutamine Reveals Altered Concentrations in Patients With Schizophrenia and Healthy Siblings

    DEFF Research Database (Denmark)

    Thakkar, Katharine N; Rösler, Lara; Wijnen, Jannie P


    BACKGROUND: The N-methyl-D-aspartate receptor hypofunction model of schizophrenia predicts dysfunction in both glutamatergic and gamma-aminobutyric acidergic (GABAergic) transmission. We addressed this hypothesis by measuring GABA, glutamate, glutamine, and the sum of glutamine plus glutamate...... concentrations in vivo in patients with schizophrenia using proton magnetic resonance spectroscopy at 7T, which allows separation of metabolites that would otherwise overlap at lower field strengths. In addition, we investigated whether altered levels of GABA, glutamate, glutamine, and the sum of glutamine plus......, and 24 healthy nonrelatives. Glutamate, glutamine, and GABA were measured cortically and subcortically in bilateral basal ganglia and occipital cortex. RESULTS: Patients with schizophrenia had reduced cortical GABA compared with healthy relatives and the combined sample of healthy relatives and healthy...

  19. Differential modulation of nicotine-induced gemcitabine resistance by GABA receptor agonists in pancreatic cancer cell xenografts and in vitro. (United States)

    Banerjee, Jheelam; Al-Wadei, Hussein An; Al-Wadei, Mohammed H; Dagnon, Koami; Schuller, Hildegard M


    Pancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicotine-induced gemcitabine resistance in pancreatic cancer. Using mouse xenografts from the gemcitabine--sensitive pancreatic cancer cell line BXPC-3, we tested the effects of GABA and baclofen on nicotine-induced gemcitabine resistance. The levels of cAMP, p-SRC, p-ERK, p-AKT, p-CREB and cleaved caspase-3 in xenograft tissues were determined by ELISA assays. Expression of the two GABA-B receptors, metalloproteinase-2 and 9 and EGR-1 in xenograft tissues was monitored by Western blotting. Mechanistic studies were conducted in vitro, using cell lines BXPC-3 and PANC-1 and included analyses of cAMP production by ELISA assay and Western blots to determine protein expression of GABA-B receptors, metalloproteinase-2 and 9 and EGR-1. Our data show that GABA was as effective as gemcitabine and significantly reversed gemcitabine resistance induced by low dose nicotine in xenografts whereas baclofen did not. These effects of GABA were accompanied by decreases in cAMP, p-CREB, p-AKT, p-Src, p-ERK metalloproteinases-9 and -2 and EGR-1 and increases in cleaved caspase-3 in xenografts whereas baclofen had the opposite effects. In vitro exposure of cells to single doses or seven days of nicotine induced the protein expression of MMP-2, MMP-9 and EGR-1 and these responses were blocked by GABA. Baclofen downregulated the protein expression of GABA-B-Rs in xenograft tissues and in cells exposed to baclofen for seven days in vitro. This response was accompanied by inversed baclofen effects from inhibition of

  20. Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the Meninges and the Choroid Plexus: Implications for Non-Neuronal Sources for GABA in the Developing Mouse Brain (United States)

    Tochitani, Shiro; Kondo, Shigeaki


    Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11–E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development. PMID:23437266

  1. Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the meninges and the choroid plexus: implications for non-neuronal sources for GABA in the developing mouse brain.

    Directory of Open Access Journals (Sweden)

    Shiro Tochitani

    Full Text Available Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67, both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11-E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development.

  2. Immunoneutralization of endogenous glucagon-like peptide-2 reduces adaptive intestinal growth in diabetic rats

    DEFF Research Database (Denmark)

    Hartmann, Bolette; Thulesen, Jesper; Hare, Kristine Juul


    in the proximal part of the small intestine (10.84+/-0.44 mm(2)). Antibody treatment had no effect on body weight, blood glucose concentrations and food intake. Thus, blocking of endogenous GLP-2 in a model of adaptive intestinal growth reduces the growth response, providing strong evidence for a physiological......Supraphysiological doses of glucagon-like peptide-2 (GLP-2) have been shown to induce intestinal growth by increasing villus height and crypt depth and by decreasing apoptosis, but a physiological effect of GLP-2 has not yet been demonstrated. Earlier, we found elevated levels of endogenous GLP-2...... in untreated streptozotocin diabetic rats associated with marked intestinal growth. In the present study, we investigated the role of endogenous GLP-2 for this adaptive response. We included four groups of six rats: (1) diabetic rats treated with saline, (2) diabetic rats treated with non-specific antibodies...

  3. Differential distribution of activated spinal neurons containing glycine and/or GABA and expressing c-fos in acute and chronic pain models. (United States)

    Hossaini, Mehdi; Duraku, Liron S; Saraç, Ciğdem; Jongen, Joost L M; Holstege, Jan C


    The inhibitory transmitters GABA and glycine play an important role in modulating pain transmission, both in normal and in pathological situations. In the present study we have combined in situ hybridization for identifying spinal neurons that use the transmitter(s) glycine and/or GABA (Gly/GABA neurons) with immunohistochemistry for c-fos, a marker for neuronal activation. This procedure was used with acute pain models induced by the injection of capsaicin or formalin; and chronic pain models using Complete Freund's Adjuvant (CFA, chronic inflammation), and the spared nerve injury (SNI) model (neuropathic pain). In all models Gly/GABA neurons were activated as indicated by their expression of c-fos. The pattern of Gly/GABA neuronal activation was different for every model, both anatomically and quantitatively. However, the averaged percentage of activated neurons that were Gly/GABA in the chronic phase (≥20h survival, 46%) was significantly higher than in the acute phase (≤2h survival, 34%). In addition, the total numbers of activated Gly/GABA neurons were similar in both phases, showing that the activation of non-Gly/GABA (presumed excitatory) neurons in the chronic phase decreased. Finally, morphine application equally decreased the total number of activated neurons and activated Gly/GABA neurons. This showed that morphine did not specifically activate Gly/GABA neurons to achieve nociceptive inhibition. The present study shows an increased activity of Gly/GABA neurons in acute and chronic models. This mechanism, together with mechanisms that antagonize the effects of GABA and glycine at the receptor level, may determine the sensitivity of our pain system during health and disease. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  4. Glucose Oscillations Can Activate an Endogenous Oscillator in Pancreatic Islets.

    Directory of Open Access Journals (Sweden)

    Joseph P McKenna


    Full Text Available Pancreatic islets manage elevations in blood glucose level by secreting insulin into the bloodstream in a pulsatile manner. Pulsatile insulin secretion is governed by islet oscillations such as bursting electrical activity and periodic Ca2+ entry in β-cells. In this report, we demonstrate that although islet oscillations are lost by fixing a glucose stimulus at a high concentration, they may be recovered by subsequently converting the glucose stimulus to a sinusoidal wave. We predict with mathematical modeling that the sinusoidal glucose signal's ability to recover islet oscillations depends on its amplitude and period, and we confirm our predictions by conducting experiments with islets using a microfluidics platform. Our results suggest a mechanism whereby oscillatory blood glucose levels recruit non-oscillating islets to enhance pulsatile insulin output from the pancreas. Our results also provide support for the main hypothesis of the Dual Oscillator Model, that a glycolytic oscillator endogenous to islet β-cells drives pulsatile insulin secretion.

  5. The effect of fermented buckwheat on producing l-carnitine- and γ-aminobutyric acid (GABA)-enriched designer eggs. (United States)

    Park, Namhyeon; Lee, Tae-Kyung; Nguyen, Thi Thanh Hanh; An, Eun-Bae; Kim, Nahyun M; You, Young-Hyun; Park, Tae-Sub; Kim, Doman


    The potential of fermented buckwheat as a feed additive was studied to increase l-carnitine and γ-aminobutyric acid (GABA) in designer eggs. Buckwheat contains high levels of lysine, methionine and glutamate, which are precursors for the synthesis of l-carnitine and GABA. Rhizopus oligosporus was used for the fermentation of buckwheat to produce l-carnitine and GABA that exert positive effects such as enhanced metabolism, antioxidant activities, immunity and blood pressure control. A novel analytical method for simultaneously detecting l-carnitine and GABA was developed using liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS. The fermented buckwheat extract contained 4 and 34 times more l-carnitine and GABA respectively compared with normal buckwheat. Compared with the control, the fermented buckwheat extract-fed group showed enriched l-carnitine (13.6%) and GABA (8.4%) in the yolk, though only l-carnitine was significantly different (P < 0.05). Egg production (9.4%), albumen weight (2.1%) and shell weight (5.8%) were significantly increased (P < 0.05). There was no significant difference in yolk weight, and total cholesterol (1.9%) and triglyceride (4.9%) in the yolk were lowered (P < 0.05). Fermented buckwheat as a feed additive has the potential to produce l-carnitine- and GABA-enriched designer eggs with enhanced nutrition and homeostasis. These designer eggs pose significant potential to be utilized in superfood production and supplement industries. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  6. Mutants of GABA transaminase (POP2 suppress the severe phenotype of succinic semialdehyde dehydrogenase (ssadh mutants in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Frank Ludewig

    Full Text Available BACKGROUND: The gamma-aminubutyrate (GABA shunt bypasses two steps of the tricarboxylic acid cycle, and is present in both prokaryotes and eukaryotes. In plants, the pathway is composed of the calcium/calmodulin-regulated cytosolic enzyme glutamate decarboxylase (GAD, the mitochondrial enzymes GABA transaminase (GABA-T; POP2 and succinic semialdehyde dehydrogenase (SSADH. We have previously shown that compromising the function of the GABA-shunt, by disrupting the SSADH gene of Arabidopsis, causes enhanced accumulation of reactive oxygen intermediates (ROIs and cell death in response to light and heat stress. However, to date, genetic investigations of the relationships between enzymes of the GABA shunt have not been reported. PRINCIPAL FINDINGS: To elucidate the role of succinic semialdehyde (SSA, gamma-hydroxybutyrate (GHB and GABA in the accumulation of ROIs, we combined two genetic approaches to suppress the severe phenotype of ssadh mutants. Analysis of double pop2 ssadh mutants revealed that pop2 is epistatic to ssadh. Moreover, we isolated EMS-generated mutants suppressing the phenotype of ssadh revealing two new pop2 alleles. By measuring thermoluminescence at high temperature, the peroxide contents of ssadh and pop2 mutants were evaluated, showing that only ssadh plants accumulate peroxides. In addition, pop2 ssadh seedlings are more sensitive to exogenous SSA or GHB relative to wild type, because GHB and/or SSA accumulate in these plants. SIGNIFICANCE: We conclude that the lack of supply of succinate and NADH to the TCA cycle is not responsible for the oxidative stress and growth retardations of ssadh mutants. Rather, we suggest that the accumulation of SSA, GHB, or both, produced downstream of the GABA-T transamination step, is toxic to the plants, resulting in high ROI levels and impaired development.

  7. Acute stress effects on GABA and glutamate levels in the prefrontal cortex: A 7T 1H magnetic resonance spectroscopy study

    Directory of Open Access Journals (Sweden)

    L.C. Houtepen


    Full Text Available There is ample evidence that the inhibitory GABA and the excitatory glutamate system are essential for an adequate response to stress. Both GABAergic and glutamatergic brain circuits modulate hypothalamus-pituitary-adrenal (HPA-axis activity, and stress in turn affects glutamate and GABA levels in the rodent brain. However, studies examining stress-induced GABA and glutamate levels in the human brain are scarce. Therefore, we investigated the influence of acute psychosocial stress (using the Trier Social Stress Test on glutamate and GABA levels in the medial prefrontal cortex of 29 healthy male individuals using 7 Tesla proton magnetic resonance spectroscopy. In vivo GABA and glutamate levels were measured before and 30 min after exposure to either the stress or the control condition. We found no associations between psychosocial stress or cortisol stress reactivity and changes over time in medial prefrontal glutamate and GABA levels. GABA and glutamate levels over time were significantly correlated in the control condition but not in the stress condition, suggesting that very subtle differential effects of stress on GABA and glutamate across individuals may occur. However, overall, acute psychosocial stress does not appear to affect in vivo medial prefrontal GABA and glutamate levels, at least this is not detectable with current practice 1H-MRS.

  8. Endogenous vs. exogenous regulations in the commons

    DEFF Research Database (Denmark)

    Abatayo, Anna Lou; Lynham, John


    It is widely believed that there is strong experimental evidence to support the idea that exogenously imposed regulations crowd out the intrinsic motivations of common pool resource (CPR) users to refrain from over-harvesting. We introduce a novel experimental design that attempts to disentangle...... levels among CPR users in a laboratory experiment. We also observe no differences between weak external regulations and no regulations, after controlling for a potential confound. However, when we add communication to our endogenous treatment, we observe significant behavioral differences between...

  9. Psychological rehabilitation of patients with endogenous disease

    Directory of Open Access Journals (Sweden)

    Tamara Kryvonis


    Full Text Available The rationale for early psychotherapeutic intervention in combination with psychopharmatherapy in patients with endogenous disorders is provided. The mechanisms of psychological defenses to deal with traumatic experience, used by personalities functioning on a psychotic level, are also described here. Characteristic behavior patterns of extended family members in terms of emotional codependence are provided. Individual pathopsychology is considered as a symptom of abnormal functioning of the family. Emphasis is placed on the importance of inclusion of family members in psychotherapeutic interaction in order to correct interpersonal relations.

  10. Environmental policy, pollution, unemployment and endogenous growth

    DEFF Research Database (Denmark)

    Pedersen, Lars Haagen; Nielsen, Søren Bo; Sørensen, Peter Birch


    The paper develops a model of endogenous economic growth with pollution externalities and a labor market distorted by union monopoly power and by taxes and transfers. We study the optimal second-best pollution tax and abatement policy and find that a shift toward greener preferences will tend...... to reduce unemployment, although it will hamper growth. We also find that greater labor-market distortions call for higher pollution tax rates. Finally, we show that a switch from quantity control of pollution combined with grandfathering of pollution rights to regulation via emission charges has...

  11. Structure and functional interaction of the extracellular domain of human GABA[subscript B] receptor GBR2

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yong; Xiong, Dazhi; Mosyak, Lidia; Malito, David L.; Kniazeff, Julie; Chen, Yan; Burmakina, Svetlana; Quick, Matthias; Bush, Martin; Javitch, Jonathan A.; Pin, Jean-Philippe; Fan, Qing R. (CNRS-UMR); (Columbia)


    Inhibitory neurotransmission is mediated primarily by GABA. The metabotropic GABA{sub B} receptor is a G protein-coupled receptor central to mammalian brain function. Malfunction of GABA{sub B} receptor has been implicated in several neurological disorders. GABA{sub B} receptor functions as a heterodimeric assembly of GBR1 and GBR2 subunits, where GBR1 is responsible for ligand-binding and GBR2 is responsible for G protein coupling. Here we demonstrate that the GBR2 ectodomain directly interacts with the GBR1 ectodomain to increase agonist affinity by selectively stabilizing the agonist-bound conformation of GBR1. We present the crystal structure of the GBR2 ectodomain, which reveals a polar heterodimeric interface. We also identify specific heterodimer contacts from both subunits, and GBR1 residues involved in ligand recognition. Lastly, our structural and functional data indicate that the GBR2 ectodomain adopts a constitutively open conformation, suggesting a structural asymmetry in the active state of GABA{sub B} receptor that is unique to the GABAergic system.

  12. An atypical residue in the pore of Varroa destructor GABA-activated RDL receptors affects picrotoxin block and thymol modulation. (United States)

    Price, Kerry L; Lummis, Sarah C R


    GABA-activated RDL receptors are the insect equivalent of mammalian GABAA receptors, and play a vital role in neurotransmission and insecticide action. Here we clone the pore lining M2 region of the Varroa mite RDL receptor and show that it has 4 atypical residues when compared to M2 regions of most other insects, including bees, which are the major host of Varroa mites. We create mutant Drosophila RDL receptors containing these substitutions and characterise their effects on function. Using two electrode voltage clamp electrophysiology we show that one substitution (T6'M) ablates picrotoxin inhibition and increases the potency of GABA. This mutation also alters the effect of thymol, which enhances both insect and mammalian GABA responses, and is widely used as a miticide. Thymol decreases the GABA EC50 of WT receptors, enhancing responses, but in T6'M-containing receptors it is inhibitory. The other 3 atypical residues have no major effects on either the GABA EC50, the picrotoxin potency or the effect of thymol. In conclusion we show that the RDL 6' residue is important for channel block, activation and modulation, and understanding its function also has the potential to prove useful in the design of Varroa-specific insecticidal agents. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. The depolarizing action of GABA in cultured hippocampal neurons is not due to the absence of ketone bodies.

    Directory of Open Access Journals (Sweden)

    Jaylyn Waddell

    Full Text Available Two recent reports propose that the depolarizing action of GABA in the immature brain is an artifact of in vitro preparations in which glucose is the only energy source. The authors argue that this does not mimic the physiological environment because the suckling rats use ketone bodies and pyruvate as major sources of metabolic energy. Here, we show that availability of physiologically relevant levels of ketone bodies has no impact on the excitatory action of GABA in immature cultured hippocampal neurons. Addition of β-hydroxybutyrate (BHB, the primary ketone body in the neonate rat, affected neither intracellular calcium elevation nor membrane depolarizations induced by the GABA-A receptor agonist muscimol, when assessed with calcium imaging or perforated patch-clamp recording, respectively. These results confirm that the addition of ketone bodies to the extracellular environment to mimic conditions in the neonatal brain does not reverse the chloride gradient and therefore render GABA hyperpolarizing. Our data are consistent with the existence of a genuine "developmental switch" mechanism in which GABA goes from having a predominantly excitatory role in immature cells to a predominantly inhibitory one in adults.

  14. Harnessing Endogenous Systems for Cancer Therapy

    DEFF Research Database (Denmark)

    Klauber, Thomas Christopher Bogh

    In the recent decade, two strategies in particular have attracted attention due to the prospect of significantly improving cancer treatment: Gene silencing therapy and immunotherapy. Both strategies work by manipulating endogenous mechanisms and theoretically promise very strong effect on the dis......In the recent decade, two strategies in particular have attracted attention due to the prospect of significantly improving cancer treatment: Gene silencing therapy and immunotherapy. Both strategies work by manipulating endogenous mechanisms and theoretically promise very strong effect...... immunotherapy (Project II). Transfer into the clinic of therapies based on gene silencing by siRNA delivered by synthetic vectors has yet to happen. A major reason is the lack of efficiency in the delivery process, partly due to insufficient understanding of cellular uptake and processing of the si...... to the conventional PEIs. However, lipid conjugation did not sufficiently reduce the inherent toxicity associated with high molecular weight PEI, and lipid conjugation of bPEI did also not change the ability of bPEI to affect lysosomal pH as a function of time. In contrast to gene silencing therapy, cancer...

  15. Cerebral radioprotection by pentobarbital: Dose-response characteristics and association with GABA agonist activity

    Energy Technology Data Exchange (ETDEWEB)

    Olson, J.J.; Friedman, R.; Orr, K.; Delaney, T.; Oldfield, E.H. (National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD (USA))


    Pentobarbital reduces cerebral radiation toxicity; however, the mechanism of this phenomenon remains unknown. As an anesthetic and depressant of cerebral metabolism, pentobarbital induces its effects on the central nervous system by stimulating the binding of gamma-aminobutyric acid (GABA) to its receptor and by inhibiting postsynaptic excitatory amino acid activity. The purpose of this study is to investigate the role of these actions as well as other aspects of the radioprotective activity of pentobarbital. Fischer 344 rats were separated into multiple groups and underwent two dose-response evaluations. In one set of experiments to examine the relationship of radioprotection to pentobarbital dose, a range of pentobarbital doses (0 to 75 mg/kg) were given intraperitoneally prior to a constant-level radiation dose (70 Gy). In a second series of experiments to determine the dose-response relationship of radiation protection to radiation dose, a range of radiation doses (10 to 90 Gy) were given with a single pentobarbital dose. Further groups of animals were used to evaluate the importance of the timing of pentobarbital administration, the function of the (+) and (-) isomers of pentobarbital, and the role of an alternative GABA agonist (diazepam). In addition, the potential protective effects of alternative methods of anesthesia (ketamine) and induction of cerebral hypometabolism (hypothermia) were examined. Enhancement of survival time from acute radiation injury due to high-dose single-fraction whole-brain irradiation was maximal with 60 mg/kg of pentobarbital, and occurred over the range of all doses examined between 30 to 90 Gy. Protection was seen only in animals that received the pentobarbital before irradiation. Administration of other compounds that enhance GABA binding (Saffan and diazepam) also significantly enhanced survival time.

  16. Effect of the GABA B agonist baclofen on dipyrone-induced delayed gastric emptying in rats

    Directory of Open Access Journals (Sweden)

    E.F. Collares


    Full Text Available Dipyrone administered intravenously (iv or intracerebroventricularly (icv delays gastric emptying (GE in rats. Gamma-aminobutyric acid (GABA is the most potent inhibitory neurotransmitter of the central nervous system. The objective of the present study was to determine the effect of icv baclofen, a GABA B receptor agonist, on delayed GE induced by dipyrone. Adult male Wistar rats received a saline test meal containing phenol red as a marker. GE was indirectly evaluated by determining the percent of gastric retention (%GR of the meal 10 min after orogastric administration. In the first experiment, the animals were injected iv with vehicle (Civ or 80 mg/kg (240 µmol/kg dipyrone (Dp iv, followed by icv injection of 10 µl vehicle (bac0, or 0.5 (bac0.5, 1 (bac1 or 2 µg (bac2 baclofen. In the second experiment, the animals were injected icv with 5 µl vehicle (Cicv or an equal volume of a solution containing 4 µmol (1333.2 µg dipyrone (Dp icv, followed by 5 µl vehicle (bac0 or 1 µg baclofen (bac1. GE was determined 10 min after icv injection. There was no significant difference between control animals from one experiment to another concerning GR values. Baclofen at the doses of 1 and 2 µg significantly reduced mean %GR induced by iv dipyrone (Dp iv bac1 = 35.9% and Dp iv bac2 = 26.9% vs Dp iv bac0 = 51.8%. Similarly, baclofen significantly reduced the effect of dipyrone injected icv (mean %GR: Dp icv bac1 = 30.4% vs Dp icv bac0 = 54.2%. The present results suggest that dipyrone induces delayed GE through a route in the central nervous system that is blocked by the activation of GABA B receptors.

  17. Colorimetric detection of endogenous hydrogen sulfide production in living cells (United States)

    Ahn, Yong Jin; Lee, Young Ju; Lee, Jaemyeon; Lee, Doyeon; Park, Hun-Kuk; Lee, Gi-Ja


    Hydrogen sulfide (H2S) has received great attention as a third gaseous signal transmitter, following nitric oxide and carbon monoxide. In particular, H2S plays an important role in the regulation of cancer cell biology. Therefore, the detection of endogenous H2S concentrations within biological systems can be helpful to understand the role of gasotransmitters in pathophysiology. Although a simple and inexpensive method for the detection of H2S has been developed, its direct and precise measurement in living cells remains a challenge. In this study, we introduced a simple, facile, and inexpensive colorimetric system for selective H2S detection in living cells using a silver-embedded Nafion/polyvinylpyrrolidone (PVP) membrane. This membrane could be easily applied onto a polystyrene microplate cover. First, we optimized the composition of the coating membrane, such as the PVP/Nafion mixing ratio and AgNO3 concentration, as well as the pH of the Na2S (H2S donor) solution and the reaction time. Next, the in vitro performance of a colorimetric detection assay utilizing the silver/Nafion/PVP membrane was evaluated utilizing a known concentration of Na2S standard solution both at room temperature and at 37 °C in a 5% CO2 incubator. As a result, the sensitivity of the colorimetric assay for H2S at 37 °C in the incubator (0.0056 Abs./μM Na2S, R2 = 0.9948) was similar to that at room temperature (0.0055 Abs./μM Na2S, R2 = 0.9967). Moreover, these assays were less sensitive to interference from compounds such as glutathione, L-cysteine (Cys), and dithiothreitol than to the H2S from Na2S. This assay based on the silver/Nafion/PVP membrane also showed excellent reproducibility (2.8% RSD). Finally, we successfully measured the endogenous H2S concentrations in live C6 glioma cells by s-(5‧-adenosyl)-L-methionine stimulation with and without Cys and L-homocysteine, utilizing the silver/Nafion/PVP membrane. In summary, colorimetric assays using silver

  18. Biological Redundancy of Endogenous GPCR Ligands in the Gut and the Potential for Endogenous Functional Selectivity

    Directory of Open Access Journals (Sweden)

    Georgina eThompson


    Full Text Available This review focuses on the existence and function of multiple endogenous agonists of the somatostatin and opioid receptors with an emphasis on their expression in the gastrointestinal tract (GIT. These agonists generally arise from the proteolytic cleavage of prepropeptides during peptide maturation or from degradation of peptides by extracellular or intracellular endopeptidases. In other examples, endogenous peptide agonists for the same G protein-coupled receptors can be products of distinct genes but contain high sequence homology. This apparent biological redundancy has recently been challenged by the realization that different ligands may engender distinct receptor conformations linked to different intracellular signaling profiles and, as such the existence of distinct ligands may underlie mechanisms to finely tune physiological responses. We propose that further characterization of signaling pathways activated by these endogenous ligands will provide invaluable insight into the mechanisms governing biased agonism. Moreover, these ligands may prove useful in the design of novel therapeutic tools to target distinct signaling pathways, thereby favoring desirable effects and limiting detrimental on-target effects. Finally we will discuss the limitations of this area of research and we will highlight the difficulties that need to be addressed when examining endogenous bias in tissues and in animals.

  19. On Taxation in a Two-Sector Endogenous Growth Model with Endogenous Labor Supply

    NARCIS (Netherlands)

    P.A. de Hek (Paul)


    textabstractThis paper examines the effects of taxation on long-run growth in a two-sector endogenous growth model with (i) physical capital as an input in the education sector and (ii) leisure as an additional argument in the utility function. The analysis of the effects of taxation - including

  20. Live imaging of endogenous PSD-95 using ENABLED: a conditional strategy to fluorescently label endogenous proteins. (United States)

    Fortin, Dale A; Tillo, Shane E; Yang, Guang; Rah, Jong-Cheol; Melander, Joshua B; Bai, Suxia; Soler-Cedeño, Omar; Qin, Maozhen; Zemelman, Boris V; Guo, Caiying; Mao, Tianyi; Zhong, Haining


    Stoichiometric labeling of endogenous synaptic proteins for high-contrast live-cell imaging in brain tissue remains challenging. Here, we describe a conditional mouse genetic strategy termed endogenous labeling via exon duplication (ENABLED), which can be used to fluorescently label endogenous proteins with near ideal properties in all neurons, a sparse subset of neurons, or specific neuronal subtypes. We used this method to label the postsynaptic density protein PSD-95 with mVenus without overexpression side effects. We demonstrated that mVenus-tagged PSD-95 is functionally equivalent to wild-type PSD-95 and that PSD-95 is present in nearly all dendritic spines in CA1 neurons. Within spines, while PSD-95 exhibited low mobility under basal conditions, its levels could be regulated by chronic changes in neuronal activity. Notably, labeled PSD-95 also allowed us to visualize and unambiguously examine otherwise-unidentifiable excitatory shaft synapses in aspiny neurons, such as parvalbumin-positive interneurons and dopaminergic neurons. Our results demonstrate that the ENABLED strategy provides a valuable new approach to study the dynamics of endogenous synaptic proteins in vivo. Copyright © 2014 the authors 0270-6474/14/3416698-15$15.00/0.

  1. EEG-β/γ spectral power elevation in rat: a translatable biomarker elicited by GABA(Aα2/3)-positive allosteric modulators at nonsedating anxiolytic doses. (United States)

    Christian, Edward P; Snyder, Dean H; Song, Wei; Gurley, David A; Smolka, Joanne; Maier, Donna L; Ding, Min; Gharahdaghi, Farzin; Liu, Xiaodong F; Chopra, Maninder; Ribadeneira, Maria; Chapdelaine, Marc J; Dudley, Adam; Arriza, Jeffrey L; Maciag, Carla; Quirk, Michael C; Doherty, James J


    Benzodiazepine drugs, through interaction with GABA(Aα1), GABA(Aα2,3), and GABA(Aα5) subunits, modulate cortical network oscillations, as reflected by a complex signature in the EEG power spectrum. Recent drug discovery efforts have developed GABA(Aα2,3)-subunit-selective partial modulators in an effort to dissociate the side effect liabilities from the efficacy imparted by benzodiazepines. Here, we evaluated rat EEG and behavioral end points during dosing of nine chemically distinct compounds that we confirmed statistically to selectively to enhance GABA(Aα2,3)-mediated vs. GABA(Aα1) or GABA(Aα5) currents in voltage clamped oocytes transfected with those GABA(A) subunits. These compounds were shown with in vivo receptor occupancy techniques to competitively displace [(3)H]flumazenil in multiple brain regions following peripheral administration at increasing doses. Over the same dose range, the compounds all produced dose-dependent EEG spectral power increases in the β- and and γ-bands. Finally, the dose range that increased γ-power coincided with that eliciting punished over unpunished responding in a behavioral conflict model of anxiety, indicative of anxiolysis without sedation. EEG γ-band power increases showed a significant positive correlation to in vitro GABA(Aα2,3) modulatory intrinsic activity across the compound set, further supporting a hypothesis that this EEG signature was linked specifically to pharmacological modulation of GABA(Aα2,3) signaling. These findings encourage further evaluation of this EEG signature as a noninvasive clinical translational biomarker that could ultimately facilitate development of GABA(Aα2,3)-subtype-selective drugs for anxiety and potentially other indications. Copyright © 2015 the American Physiological Society.





    La disponibilidad de los receptores en membrana está controlada por mecanismos de tráfico intracelular, los cuales han sido ampliamente estudiados para los receptores ele glutamato y relacionados con fenómenos plásticos como L TP y L TD. Estos a su vez han sido relacionados con procesos cognitivos como memoria y aprendizaje. Se conoce poco acerca de la importancia del tráfico de los receptores gabaérgicos sobre la plasticidad. Este conocimiento es virtualmente nulo en el caso d...

  3. Ligands for expression cloning and isolation of GABA(B) receptors. (United States)

    Froestl, Wolfgang; Bettler, Bernhard; Bittiger, Helmut; Heid, Jakob; Kaupmann, Klemens; Mickel, Stuart J; Strub, Dietrich


    The scope of the plenary lecture at the occasion of the Xth Meeting on Heterocyclic Structures in Medicinal Chemistry, Palermo 2002, is considerably larger than that of the main lecture at the XVIth International Symposium on Medicinal Chemistry, Bologna 2000, described by Froestl et al. in Farmaco 56 (2001) 101. Additional information is presented, in particular, on the reaction conditions for the 31 step synthesis of the combined affinity chromatography and photoaffinity radioligand [125I]CGP84963 and on the recent developments of the molecular biology of GABA(B) receptors. Copyright 2003 Editions scienctifiques et médicales Elsevier SAS

  4. Normalizing data from GABA-edited MEGA-PRESS implementations at 3 Tesla. (United States)

    Harris, Ashley D; Puts, Nicolaas A J; Wijtenburg, S Andrea; Rowland, Laura M; Mikkelsen, Mark; Barker, Peter B; Evans, C John; Edden, Richard A E


    Standardization of results is an important milestone in the maturation of any truly quantitative methodology. For instance, a lack of measurement agreement across imaging platforms limits multisite studies, between-study comparisons based on the literature, and inferences based on and the generalizability of results. In GABA-edited MEGA-PRESS, two key sources of differences between implementations are: differences in editing efficiency of GABA and the degree of co-editing of macromolecules (MM). In this work, GABA editing efficiency κ and MM-co-editing μ constants are determined for three widely used MEGA-PRESS implementations (on the most common MRI platforms; GE, Philips, and Siemens) by phantom experiments. Implementation-specific κ,μ-corrections were then applied to two in vivo datasets, one consisted of 8 subject scanned on the three platforms and the other one subject scanned eight times on each platform. Manufacturer-specific κ and μ values were determined as: κGE=0.436, κSiemens=0.366 and κPhilips=0.394 and μGE=0.83, μSiemens=0.625 and μPhilips=0.75. Applying the κ,μ-correction on the Cr-referenced data decreased the coefficient of variation (CV) of the data for both in vivo data sets (multisubjects: uncorrected CV=13%, κ,μ-corrected CV=5%, single subject: uncorrected CV=23%, κ,μ-corrected CV=13%) but had no significant effect on mean GABA levels. For the water-referenced results, CV increased in the multisubject data (uncorrected CV=6.7%, κ,μ-corrected CV=14%) while it decreased in the single subject data (uncorrected CV=24%, κ,μ-corrected CV=21%) and manufacturer was a significant source of variance in the κ,μ-corrected data. Applying a correction for editing efficiency and macromolecule contamination decreases the variance between different manufacturers for creatine-referenced data, but other sources of variance remain. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Positive allosteric modulation of GABA-A receptors reduces capsaicin-induced primary and secondary hypersensitivity in rats

    DEFF Research Database (Denmark)

    Hansen, Rikke Rie; Erichsen, Helle K; Brown, David T


    this concept being tested in humans. Prior to assessing the efficacy of GABA-A receptor PAMs in a human volunteer pain model we have compared compounds capable of variously modulating GABA-A receptor function in comparable rat models of capsaicin-induced acute nocifensive flinching behaviour and secondary...... mechanical hypersensitivity. The subtype-selective PAM NS11394 (0.3-10 mg/kg), and the non-selective PAM diazepam (1-5 mg/kg) variously reduced capsaicin-induced secondary mechanical hypersensitivity (180 min post-injection). However, the low efficacy subtype-selective PAM TPA023 (3-30 mg/kg) was completely......, albeit at doses previously shown to impair locomotor function. Our data indicate that GABA-A receptor PAMs with optimal selectivity and efficacy profiles reduce centrally-mediated mechanical hypersensitivity in capsaicin-injected rats, an observation that we expect can translate directly to human...

  6. Endogenous Oxytocin, Vasopressin, and Aggression in Domestic Dogs. (United States)

    MacLean, Evan L; Gesquiere, Laurence R; Gruen, Margaret E; Sherman, Barbara L; Martin, W Lance; Carter, C Sue


    Aggressive behavior in dogs poses public health and animal welfare concerns, however the biological mechanisms regulating dog aggression are not well understood. We investigated the relationships between endogenous plasma oxytocin (OT) and vasopressin (AVP)-neuropeptides that have been linked to affiliative and aggressive behavior in other mammalian species-and aggression in domestic dogs. We first validated enzyme-linked immunosorbent assays (ELISAs) for the measurement of free (unbound) and total (free + bound) OT and AVP in dog plasma. In Experiment 1 we evaluated behavioral and neuroendocrine differences between a population of pet dogs with a history of chronic aggression toward conspecifics and a matched control group. Dogs with a history of aggression exhibited more aggressive behavior during simulated encounters with conspecifics, and had lower free, but higher total plasma AVP than matched controls, but there were no group differences for OT. In Experiment 2 we compared OT and AVP concentrations between pet dogs and a population of assistance dogs that have been bred for affiliative and non-aggressive temperaments, and investigated neuroendocrine predictors of individual differences in social behavior within the assistance dog population. Compared to pet dogs, assistance dogs had higher free and total OT, but there were no differences in either measure for AVP. Within the assistance dog population, dogs who behaved more aggressively toward a threatening stranger had higher total AVP than dogs who did not. Collectively these data suggest that endogenous OT and AVP may play critical roles in shaping dog social behavior, including aspects of both affiliation and aggression.

  7. Endogenous ACh tonically stimulates ANP secretion in rat atria. (United States)

    Kim, Hye Yoom; Cho, Kyung Woo; Xu, Dong Yuan; Kang, Dae Gill; Lee, Ho Sub


    Exogenous acetylcholine (ACh) is known to stimulate atrial natriuretic peptide (ANP) secretion concomitantly with a decrease in atrial pulse pressure. However, the role of intrinsic ACh in the regulation of ANP secretion remains unknown. Recently, it was shown that nonneuronal and neuronal ACh is present in the cardiac atria. From this finding we hypothesize that endogenously released ACh is involved in the regulation of ANP secretion in an autocrine or paracrine manner in the atria. Experiments were performed in isolated beating rat atria. ANP was measured using radioimmunoassay. To increase the availability of the ACh in the extracellular space of the atrium, its degradation was inhibited with an inhibitor of acetylcholinesterase. Acetylcholinesterase inhibition with physostigmine increased ANP secretion concomitantly with a decrease in atrial dynamics in a concentration-dependent manner. Inhibitors of M2 muscarinic ACh receptor (mAChR), methoctramine, and ACh-activated K(+) (KACh(+)) channels, tertiapin-Q, abolished the physostigmine-induced changes. The effects were not observed in the atria from rats treated with pertussis toxin. Furthermore, the physostigmine-induced effects were attenuated by an inhibitor of high-affinity choline transporter, hemicholinium-3, which is a rate-limiting step of ACh synthesis. Inhibitors of the mAChR signaling pathway and ACh synthesis also attenuated the basal levels of ANP secretion and accentuated atrial dynamics. These findings suggest that endogenously released ACh tonically stimulates ANP secretion from atrial cardiomyocytes via activation of M2 mAChR-Gi/o-KACh(+) channel signaling. It is also suggested that the ACh-ANP signaling is implicated in cardiac physiology and pathophysiology.

  8. [Distribution of endogenous inhibitors of the respiratory chain in plants]. (United States)

    Schewe, T; Walther, H; Redmann, T; Rapoport, S


    70 phosphate buffer extracts of various plant tissues of 40 species as well as of 2 bacteria were tested for the presence of endogenous inhibitors of the respiratory chain. Electron transfer particles (ETP) from beef heart mitochondria served as test object. The NADH oxidase (spectrophotometrically) and the succinate oxidase activity (manometrically) were measured. Inhibitory activities could be detected in all the plant species tested, but there were quantitative differences by orders of magnitude. The inhibitory effects were more frequent and higher in the NADH oxidase system than those in the succinate oxidase system. The highest inhibitory activities were observed with blossoms of Forsynthia intermedia, male blossoms of Corylus avellana, inflorescences of Brassica oleracea, fronds of Pteridium aquilinum and gallnuts of Quercus. The specific inhibitory activities (related to the dry mass of the extracts) suggest very efficient inhibitors having concentrations of half-inhibition in the muM-range. With 6 extracts the inhibitory activity on the NADH oxidase system was completely destroyed by boiling (Brassica oleracea, Amoracia rusticana, leaves of Digitalis purpurea, roots of Allium cepa, fruit pips of Malus domestica and mushrooms of Lactarius vellereus). The results with some plant species (Bryophyllum daigremonteanum, Allium cepa, male blossoms of Corylus avellana, Pteridium aquilinum) suggest a biological dynamics of the inhibitory activity. The inhibitor from Bryophyllum was partially characterized with regard to its mode of action. The following supposed biological functions of endogenous respiratory inhibitors of plants are discussed: 1. Involvement in the degradation of mitochondria in the course of differentiation, maturation and involution processes as well as in biologically controlled senescence processes; 2. A switch-over to the alternative mitochondrial respiratory pathway; 3. Induction and maintenance of a resting metabolism, e.g. in dormancy, by

  9. Endogenous Oxytocin, Vasopressin, and Aggression in Domestic Dogs

    Directory of Open Access Journals (Sweden)

    Evan L. MacLean


    Full Text Available Aggressive behavior in dogs poses public health and animal welfare concerns, however the biological mechanisms regulating dog aggression are not well understood. We investigated the relationships between endogenous plasma oxytocin (OT and vasopressin (AVP—neuropeptides that have been linked to affiliative and aggressive behavior in other mammalian species—and aggression in domestic dogs. We first validated enzyme-linked immunosorbent assays (ELISAs for the measurement of free (unbound and total (free + bound OT and AVP in dog plasma. In Experiment 1 we evaluated behavioral and neuroendocrine differences between a population of pet dogs with a history of chronic aggression toward conspecifics and a matched control group. Dogs with a history of aggression exhibited more aggressive behavior during simulated encounters with conspecifics, and had lower free, but higher total plasma AVP than matched controls, but there were no group differences for OT. In Experiment 2 we compared OT and AVP concentrations between pet dogs and a population of assistance dogs that have been bred for affiliative and non-aggressive temperaments, and investigated neuroendocrine predictors of individual differences in social behavior within the assistance dog population. Compared to pet dogs, assistance dogs had higher free and total OT, but there were no differences in either measure for AVP. Within the assistance dog population, dogs who behaved more aggressively toward a threatening stranger had higher total AVP than dogs who did not. Collectively these data suggest that endogenous OT and AVP may play critical roles in shaping dog social behavior, including aspects of both affiliation and aggression.

  10. Natriuretic Hormones, Endogenous Ouabain, and Related Sodium Transport Inhibitors

    Directory of Open Access Journals (Sweden)

    John eHamlyn


    Full Text Available The work of deWardener and colleagues stimulated longstanding interest in natriuretic hormones (NH. In addition to the atrial peptides (APs, the circulation contains unidentified physiologically-relevant NHs. One NH is controlled by the central nervous system (CNS and likely secreted by the pituitary. Its circulating activity is modulated by salt intake and the prevailing sodium concentration of the blood and intracerebroventricular fluid, and contributes to postprandial and dehydration natriuresis. The other NH, mobilized by atrial stretch, promotes natriuresis by increasing the production of intrarenal dopamine and/or nitric oxide. Both NHs have short (<35 minutes circulating half lives, depress renotubular sodium transport, and neither requires the renal nerves. The search for NHs led to endogenous cardiotonic steroids (CTS including ouabain-, digoxin-, and bufadienolide-like materials. These CTS, given acutely in high nanomole to micromole amounts into the general or renal circulations, inhibit sodium pumps and are natriuretic. Among these CTS, only bufalin is cleared sufficiently rapidly to qualify for an NH-like role. Ouabain-like CTS are cleared slowly, and when given chronically in low daily nanomole amounts, promote sodium retention, augment arterial myogenic tone, reduce renal blood flow and glomerular filtration, suppress nitric oxide in the renal vasa recta, and increase sympathetic nerve activity and blood pressure. Moreover, lowering total body sodium raises circulating endogenous ouabain. Thus, ouabain-like CTS have physiological actions that, like aldosterone, support renal sodium retention and blood pressure. In conclusion, the mammalian circulation contains two non-AP NHs. Identification of the CNS NH should be a priority.

  11. The role of genetic sex in affect regulation and expression of GABA-related genes across species

    Directory of Open Access Journals (Sweden)

    Marianne eSeney


    Full Text Available Although circulating hormones and inhibitory gamma-amino butyric acid (GABA-related factors are known to affect mood, considerable knowledge gaps persist for biological mechanisms underlying the female bias in mood disorders. Here, we combine human and mouse studies to investigate sexual dimorphism in the GABA system in the context of major depressive disorder (MDD and then use a genetic model to dissect the role of sex-related factors in GABA-related gene expression and anxiety-/depressive-like behaviors in mice. First, using meta-analysis of gene array data in human postmortem brain (N = 51 MDD subjects, 50 controls, we show that the previously-reported down-regulation in MDD of somatostatin (SST, a marker of a GABA neuron subtype, is significantly greater in women with MDD. Second, using gene co-expression network analysis in control human subjects (N = 214; 2 frontal cortex regions and expression quantitative trait loci mapping (N = 170 subjects, we show that expression of SST and the GABA-synthesizing enzymes glutamate decarboxylase 67 (GAD67 and GAD65 are tightly co-regulated and influenced by X-chromosome genetic polymorphisms. Third, using a rodent genetic model (Four Core Genotypes (FCG mice, in which genetic and gonadal sex are artificially dissociated (N ≥ 12/group, we show that genetic sex (i.e. X/Y chromosome influences both gene expression (lower Sst, Gad67, Gad65 in XY mice and anxiety-like behaviors (higher in XY mice. This suggests that in an intact male animal, the observed behavior represents the outcomes of male genetic sex increasing and male-like testosterone decreasing anxiety-like behaviors. Gonadal sex was the only factor influencing depressive-like behavior (gonadal males < gonadal females. Collectively, these combined human and mouse studies provide mechanistic insight into sexual dimorphism in mood disorders, and specifically demonstrate an unexpected role for XY genetic sex on GABA-related genes and anxiety

  12. Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys. (United States)

    McMahon, Lance R; Javors, Martin A; France, Charles P


    Benzodiazepine treatment can result in dependence as evidenced by signs of withdrawal upon discontinuation of use. Positive GABA(A) receptor modulators were examined for their capacity to attenuate flumazenil-like discriminative stimulus effects (i.e., withdrawal) that emerge upon discontinuation of chronic benzodiazepine treatment. Rhesus monkeys receiving chronic diazepam (5.6 mg(-1) kg(-1) 24 h(-1) p.o.) discriminated flumazenil (0.1 mg/kg s.c.) from vehicle. Upon discontinuation of diazepam treatment, responding switched from the vehicle to the flumazenil lever, although at different times among monkeys. The shorter-acting benzodiazepine lorazepam (3.2 mg(-1) kg(-1) 8 h(-1)) was substituted for diazepam and, 11 h after lorazepam, monkeys consistently responded on the flumazenil lever. Flumazenil-lever responding after acute lorazepam deprivation was attenuated not only by benzodiazepines (lorazepam and midazolam) but also by positive GABA(A) receptor modulators acting at neuroactive steroid (pregnanolone and alfaxalone) and barbiturate sites (pentobarbital). Deprivation-induced responding on the flumazenil lever was not attenuated by low efficacy positive GABA(A) modulators (bretazenil and L-838,417) or non-GABA(A) receptor ligands (ketamine and cocaine). Neuroactive steroids were relatively more potent than other positive GABA(A) receptor modulators in attenuating deprivation-induced flumazenil-lever responding, as compared to their relative potency in monkeys discriminating midazolam and otherwise not receiving benzodiazepine treatment. These results suggest that positive GABA(A) receptor modulators acting at different sites attenuate withdrawal induced by discontinuation of benzodiazepine treatment, consistent with previous studies suggesting that the same compounds attenuate flumazenil-precipitated withdrawal. Differences in the relative potency of positive modulators as a function of acute versus chronic benzodiazepine treatment suggest that neuroactive

  13. Lesions of nucleus accumbens affect morphine-induced release of ascorbic acid and GABA but not of glutamate in rats. (United States)

    Sun, Ji Y; Yang, Jing Y; Wang, Fang; Wang, Jian Y; Song, Wu; Su, Guang Y; Dong, Ying X; Wu, Chun F


    Our previous studies have shown that local perfusion of morphine causes an increase of extracellular ascorbic acid (AA) levels in nucleus accumbens (NAc) of freely moving rats. Lines of evidence showed that glutamatergic and GABAergic were associated with morphine-induced effects on the neurotransmission of the brain, especially on the release of AA. In the present study, the effects of morphine on the release of extracellular AA, γ-aminobutyric acid (GABA) and glutamate (Glu) in the NAc following bilateral NAc lesions induced by kainic acid (KA) were studied by using the microdialysis technique, coupled to high performance liquid chromatography with electrochemical detection (HPLC-ECD) and fluorescent detection (HPLC-FD). The results showed that local perfusion of morphine (100 µM, 1 mM) in NAc dose-dependently increased AA and GABA release, while attenuated Glu release in the NAc. Naloxone (0.4 mM) pretreated by local perfusion to the NAc, significantly blocked the effects of morphine. After NAc lesion by KA (1 µg), morphine-induced increase in AA and GABA were markedly eliminated, while decrease in Glu was not affected. The loss effect of morphine on AA and GABA release after KA lesion could be recovered by GABA agonist, musimol. These results indicate that morphine-induced AA release may be mediated at least by µ-opioid receptor. Moreover, this effect of morphine possibly depend less on the glutamatergic afferents, but more on the GABAergic circuits within this nucleus. Finally, AA release induced by local perfusion of morphine may be GABA-receptor mediated and synaptically localized in the NAc. © 2010 The Authors, Addiction Biology © 2010 Society for the Study of Addiction.

  14. Selective changes in sensitivity to benzodiazepines, and not other positive GABA(A) modulators, in rats receiving flunitrazepam chronically. (United States)

    Gerak, Lisa R


    Tolerance and dependence can develop during chronic benzodiazepine treatment; however, cross tolerance and cross dependence to positive modulators acting at other sites on GABA(A) receptors might not occur. The current study evaluated changes in sensitivity to positive GABA(A) modulators during chronic treatment with the benzodiazepine flunitrazepam to determine whether cross tolerance and cross dependence varied as a function of site of action. Eight rats responded under a fixed ratio 20 schedule of food presentation. Dose-effect curves were determined before, during and after chronic treatment with one or two daily injections of 1 mg/kg of flunitrazepam. Prior to chronic treatment, benzodiazepines (flunitrazepam, midazolam), a barbiturate (pentobarbital), a neuroactive steroid (pregnanolone), and drugs with primary mechanisms of action at receptors other than GABA(A) receptors (morphine, ketamine) dose-dependently decreased responding. Twice daily treatment with flunitrazepam produced 9.5- and 23-fold shifts to the right in the flunitrazepam and midazolam dose-effect curves, respectively. In contrast, dose-effect curves for other drugs either were not changed or were shifted less than or equal to fourfold to the right. Decreased sensitivity to benzodiazepines and not to a barbiturate or a neuroactive steroid during chronic flunitrazepam treatment indicates that tolerance and cross tolerance developed only to benzodiazepines. Despite similar acute behavioral effects among positive GABA(A) modulators, the differential development of cross tolerance suggests that adaptations at GABA(A) receptors produced by chronic benzodiazepine treatment differentially affect positive modulators depending on their site of action; such differences might be exploited to benefit patients treated daily with positive GABA(A) modulators.

  15. Binge Toluene Exposure Alters Glutamate, Glutamine and GABA in the Adolescent Rat Brain as Measured by Proton Magnetic Resonance Spectroscopy* (United States)

    Perrine, Shane A.; O'Leary-Moore, Shonagh K.; Galloway, Matthew P.; Hannigan, John H.; Bowen, Scott E.


    Despite the high incidence of toluene abuse in adolescents, little is known regarding the effect of binge exposure on neurochemical profiles during this developmental stage. In the current study, the effects of binge toluene exposure during adolescence on neurotransmitter levels were determined using high-resolution proton magnetic resonance spectroscopy ex vivo at 11.7 T. Adolescent male Sprague-Dawley rats were exposed to toluene (0, 8,000 , or 12,000 ppm) for 15 min twice daily from postnatal day 28 (P28) through P34 and then euthanized either one or seven days later (on P35 or P42) to assess glutamate, glutamine, and GABA levels in intact tissue punches from the medial prefrontal cortex (mPFC), anterior striatum and hippocampus. In the mPFC, toluene reduced glutamate one day after exposure, with no effect on GABA, while after seven days, glutamate was no longer affected but there was an increase in GABA levels. In the hippocampus, neither GABA nor glutamate was altered one day after exposure, whereas seven days after exposure, increases were observed in GABA and glutamate. Striatal glutamate and GABA levels measured after either one or seven days were not altered after toluene exposure. These findings show that one week of binge toluene inhalation selectively alters these neurotransmitters in the mPFC and hippocampus in adolescent rats, and that some of these effects endure at least one week after the exposure. The results suggest that age-dependent, differential neurochemical responses to toluene may contribute to the unique behavioral patterns associated with drug abuse among older children and young teens. PMID:21126832

  16. CB1-Dependent Long-Term Depression in Ventral Tegmental Area GABA Neurons: A Novel Target for Marijuana. (United States)

    Friend, Lindsey; Weed, Jared; Sandoval, Philip; Nufer, Teresa; Ostlund, Isaac; Edwards, Jeffrey G


    The VTA is necessary for reward behavior with dopamine cells critically involved in reward signaling. Dopamine cells in turn are innervated and regulated by neighboring inhibitory GABA cells. Using whole-cell electrophysiology in juvenile-adolescent GAD67-GFP male mice, we examined excitatory plasticity in fluorescent VTA GABA cells. A novel CB1-dependent LTD was induced in GABA cells that was dependent on metabotropic glutamate receptor 5, and cannabinoid receptor 1 (CB1). LTD was absent in CB1 knock-out mice but preserved in heterozygous littermates. Bath applied Δ 9 -tetrahydrocannabinol depressed GABA cell activity, therefore downstream dopamine cells will be disinhibited; and thus, this could potentially result in increased reward. Chronic injections of Δ 9 -tetrahydrocannabinol occluded LTD compared with vehicle injections; however, a single exposure was insufficient to do so. As synaptic modifications by drugs of abuse are often tied to addiction, these data suggest a possible mechanism for the addictive effects of Δ 9 -tetrahydrocannabinol in juvenile-adolescents, by potentially altering reward behavioral outcomes. SIGNIFICANCE STATEMENT The present study identifies a novel form of glutamatergic synaptic plasticity in VTA GABA neurons, a currently understudied cell type that is critical for the brain's reward circuit, and how Δ 9 -tetrahydrocannabinol occludes this plasticity. This study specifically addresses a potential unifying mechanism whereby marijuana could exert rewarding and addictive/withdrawal effects. Marijuana use and legalization are a pressing issue for many states in the United States. Although marijuana is the most commonly abused illicit drug, the implications of legalized, widespread, or continued usage are speculative. This study in juvenile-adolescent aged mice identifies a novel form of synaptic plasticity in VTA GABA cells, and the synaptic remodeling that can occur after Δ 9 -tetrahydrocannabinol use. Copyright © 2017 the

  17. Monoterpene α-thujone exerts a differential inhibitory action on GABA(A) receptors implicated in phasic and tonic GABAergic inhibition. (United States)

    Czyzewska, Marta M; Mozrzymas, Jerzy W


    A monoterpene ketone, α-thujone originally attracted attention as a major natural ingredient of absinthe and was suspected to cause adverse effects such as hallucinations and seizures in persons excessively consuming this beverage. Although subsequent studies ruled out any major role of α-thujone in the "absynthism", it was found that at high doses it may induce epileptic activity pointing to an interaction with GABAergic inhibition. Indeed, subsequent studies, including those from this laboratory, showed that α-thujone inhibits GABAergic currents. However, GABAA receptors are extremely heterogeneous and in the present study we have investigated the effect of α-thujone on different recombinant GABAA receptors (α1β2γ2L, α1β2, α1β2δ and α4β2δ) relevant to phasic or tonic forms of inhibition. We report that α-thujone inhibits all considered receptor types by a qualitatively similar mechanism but the strongest effect is observed for α1β2δ receptors, suggesting that tonic currents might be more sensitive to α-thujone than the phasic ones. Moreover, we demonstrate that tonic currents, mimicked by response to a submicromollar GABA concentration (0.3 μM) in cultured neurons, showed a substantially larger sensitivity to α-thujone than responses elicited by higher [GABA] (more similar to phasic currents) or Inhibitory Postsynaptic Currents in the same preparation. Importantly, the extent of tonic current inhibition by α-thujone was as strong as in the case of currents mediated by α1β2δ receptors. Altogether, these data provide evidence that different GABAA receptor subtypes show distinct sensitivities to α-thujone and suggest that this compound may differentially affect tonic and phasic components of GABAergic inhibition. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Changing Endogenous Development: the Territorial Capital

    Directory of Open Access Journals (Sweden)

    Balázs István Tóth


    Full Text Available The aim of this research is to analyze territorial capital as a new paradigm to make best use of endogenous assets. The study is dealing with the preconditions, meaning and possible theoretical taxonomies of territorial capital. In this study I emphasize that the cumulative effects of regional potentials are more important than economies of scale and location factors. I present different approaches and interpretations of territorial capital, then make an attempt to create an own model. I try to find answers for questions, such as why territorial capital shows a new perspective of urban and regional development; how cognitive elements of territorial capital provide increasing return; how territorial capital influences competitiveness and what kind of relation it has with cohesion.

  19. Endogenous Natural Complement Inhibitor Regulates Cardiac Development

    DEFF Research Database (Denmark)

    Mortensen, Simon A; Skov, Louise L; Kjaer-Sorensen, Kasper


    Congenital heart defects are a major cause of perinatal mortality and morbidity, affecting >1% of all live births in the Western world, yet a large fraction of such defects have an unknown etiology. Recent studies demonstrated surprising dual roles for immune-related molecules and their effector...... protease (MASP)-3/collectin-L1/K1 hetero-oligomer, which impacts cardiac neural crest cell migration. We used knockdown and rescue strategies in zebrafish, a model allowing visualization and assessment of heart function, even in the presence of severe functional defects. Knockdown of embryonic expression...... of MAp44 caused impaired cardiogenesis, lowered heart rate, and decreased cardiac output. These defects were associated with aberrant neural crest cell behavior. We found that MAp44 competed with