WorldWideScience

Sample records for receptor agonist activity

  1. Glutamate receptor agonists

    DEFF Research Database (Denmark)

    Vogensen, Stine Byskov; Greenwood, Jeremy R; Bunch, Lennart

    2011-01-01

    The neurotransmitter (S)-glutamate [(S)-Glu] is responsible for most of the excitatory neurotransmission in the central nervous system. The effect of (S)-Glu is mediated by both ionotropic and metabotropic receptors. Glutamate receptor agonists are generally a-amino acids with one or more...... stereogenic centers due to strict requirements in the agonist binding pocket of the activated state of the receptor. By contrast, there are many examples of achiral competitive antagonists. The present review addresses how stereochemistry affects the activity of glutamate receptor ligands. The review focuses...... mainly on agonists and discusses stereochemical and conformational considerations as well as biostructural knowledge of the agonist binding pockets, which is useful in the design of glutamate receptor agonists. Examples are chosen to demonstrate how stereochemistry not only determines how the agonist...

  2. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  3. Mechanical stress activates NMDA receptors in the absence of agonists.

    Science.gov (United States)

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K; Sachs, Frederick; Hua, Susan Z

    2017-01-03

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca 2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca 2+ influx. Extracellular Mg 2+ at 2 mM did not significantly affect the shear induced Ca 2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI.

  4. Mechanical stress activates NMDA receptors in the absence of agonists

    OpenAIRE

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K.; Sachs, Frederick; Hua, Susan Z.

    2017-01-01

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor i...

  5. Agonists and partial agonists of rhodopsin: retinal polyene methylation affects receptor activation.

    Science.gov (United States)

    Vogel, Reiner; Lüdeke, Steffen; Siebert, Friedrich; Sakmar, Thomas P; Hirshfeld, Amiram; Sheves, Mordechai

    2006-02-14

    Using Fourier transform infrared (FTIR) difference spectroscopy, we have studied the impact of sites and extent of methylation of the retinal polyene with respect to position and thermodynamic parameters of the conformational equilibrium between the Meta I and Meta II photoproducts of rhodopsin. Deletion of methyl groups to form 9-demethyl and 13-demethyl analogues, as well as addition of a methyl group at C10 or C12, shifted the Meta I/Meta II equilibrium toward Meta I, such that the retinal analogues behaved like partial agonists. This equilibrium shift resulted from an apparent reduction of the entropy gain of the transition of up to 65%, which was only partially offset by a concomitant reduction of the enthalpy increase. The analogues produced Meta II photoproducts with relatively small alterations, while their Meta I states were significantly altered, which accounted for the aberrant transitions to Meta II. Addition of a methyl group at C14 influenced the thermodynamic parameters but had little impact on the position of the Meta I/Meta II equilibrium. Neutralization of the residue 134 in the E134Q opsin mutant increased the Meta II content of the 13-demethyl analogue, but not of the 9-demethyl analogue, indicating a severe impairment of the allosteric coupling between the conserved cytoplasmic ERY motif involved in proton uptake and the Schiff base/Glu 113 microdomain in the 9-demethyl analogue. The 9-methyl group appears therefore essential for the correct positioning of retinal to link protonation of the cytoplasmic motif with protonation of Glu 113 during receptor activation.

  6. Distinct conformational changes in activated agonist-bound and agonist-free glycine receptor subunits

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Lynch, Joseph W

    2009-01-01

    Ligand binding to Cys-loop receptors produces either global conformational changes that lead to activation or local conformational changes that do not. We found that the fluorescence of a fluorophore tethered to R271C in the extracellular M2 region of the alpha1 glycine receptor increases during ...

  7. PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR) AGONISTS AS PROMISING NEW MEDICATIONS FOR DRUG ADDICTION: PRECLINICAL EVIDENCE

    Science.gov (United States)

    Foll, Bernard Le; Ciano, Patricia Di; Panlilio, Leigh V.; Goldberg, Steven R.; Ciccocioppo, Roberto

    2013-01-01

    This review examines the growing literature on the role of peroxisome proliferator-activated receptors (PPARs) in addiction. There are two subtypes of PPAR receptors that have been studied in addiction: PPAR-α and PPAR-γ. The role of each PPAR subtype in common models of addictive behavior, mainly pre-clinical models, is summarized. In particular, studies are reviewed that investigated the effects of PPAR-α agonists on relapse, sensitization, conditioned place preference, withdrawal and drug intake, and effects of PPAR-γ agonists on relapse, withdrawal and drug intake. Finally, studies that investigated the effects of PPAR agonists on neural pathways of addiction are reviewed. Taken together this preclinical data indicates that PPAR agonists are promising new medications for drug addiction treatment. PMID:23614675

  8. Non-Acidic Free Fatty Acid Receptor 4 Agonists with Antidiabetic Activity

    DEFF Research Database (Denmark)

    Goncalves de Azavedo, Carlos M. B. P.; Watterson, Kenneth R; Wargent, Ed T

    2016-01-01

    The free fatty acid receptor 4 (FFA4 or GPR120) has appeared as an interesting potential target for the treatment of metabolic disorders. At present, most FFA4 ligands are carboxylic acids that are assumed to mimic the endogenous long-chain fatty acid agonists. Here, we report preliminary structure......-activity relationship studies of a previously disclosed non-acidic sulfonamide FFA4 agonist. Mutagenesis studies indicate that the compounds are orthosteric agonists despite the absence of a carboxylate function. The preferred compounds showed full agonist activity on FFA4 and complete selectivity over FFA1, although...... a significant fraction of these non-carboxylic acids also showed partial antagonistic activity on FFA1. Studies in normal and diet-induced obese (DIO) mice with the preferred compound 34 showed improved glucose tolerance after oral dosing in an oral glucose tolerance test. Chronic dosing of 34 in DIO mice...

  9. Allosteric activation of the follicle-stimulating hormone (FSH) receptor by selective, nonpeptide agonists.

    Science.gov (United States)

    Yanofsky, Stephen D; Shen, Emily S; Holden, Frank; Whitehorn, Erik; Aguilar, Barbara; Tate, Emily; Holmes, Christopher P; Scheuerman, Randall; MacLean, Derek; Wu, May M; Frail, Donald E; López, Francisco J; Winneker, Richard; Arey, Brian J; Barrett, Ronald W

    2006-05-12

    The pituitary glycoprotein hormones, luteinizing hormone and follicle-stimulating hormone (FSH), act through their cognate receptors to initiate a series of coordinated physiological events that results in germ cell maturation. Given the importance of FSH in regulating folliculogenesis and fertility, the development of FSH mimetics has been sought to treat infertility. Currently, purified and recombinant human FSH are the only FSH receptor (FSH-R) agonists available for infertility treatment. By screening unbiased combinatorial chemistry libraries, using a cAMP-responsive luciferase reporter assay, we discovered thiazolidinone agonists (EC50's = 20 microm) of the human FSH-R. Subsequent analog library screening and parallel synthesis optimization resulted in the identification of a potent agonist (EC50 = 2 nm) with full efficacy compared with FSH that was FSH-R-selective and -dependent. The compound mediated progesterone production in Y1 cells transfected with the human FSH-R (EC50 = 980 nm) and estradiol production from primary rat ovarian granulosa cells (EC50 = 10.5 nm). This and related compounds did not compete with FSH for binding to the FSH-R. Use of human FSH/thyroid-stimulating hormone (TSH) receptor chimeras suggested a novel mechanism for receptor activation through a binding site independent of the natural hormone binding site. This study is the first report of a high affinity small molecule agonist that activates a glycoprotein hormone receptor through an allosteric mechanism. The small molecule FSH receptor agonists described here could lead to an oral alternative to the current parenteral FSH treatments used clinically to induce ovarian stimulation for both in vivo and in vitro fertilization therapy.

  10. The non-biphenyl-tetrazole angiotensin AT1 receptor antagonist eprosartan is a unique and robust inverse agonist of the active state of the AT1 receptor.

    Science.gov (United States)

    Takezako, Takanobu; Unal, Hamiyet; Karnik, Sadashiva S; Node, Koichi

    2018-03-23

    Conditions such as hypertension and renal allograft rejection are accompanied by chronic, agonist-independent, signalling by angiotensin II AT 1 receptors. The current treatment paradigm for these diseases entails the preferred use of inverse agonist AT 1 receptor blockers (ARBs). However, variability in the inverse agonist activities of common biphenyl-tetrazole ARBs for the active state of AT 1 receptors often leads to treatment failure. Therefore, characterization of robust inverse agonist ARBs for the active state of AT 1 receptors is necessary. To identify the robust inverse agonist for active state of AT 1 receptors and its molecular mechanism, we performed site-directed mutagenesis, competition binding assay, inositol phosphate production assay and molecular modelling for both ground-state wild-type AT 1 receptors and active-state N111G mutant AT 1 receptors. Although candesartan and telmisartan exhibited weaker inverse agonist activity for N111G- compared with WT-AT 1 receptors, only eprosartan exhibited robust inverse agonist activity for both N111G- and WT- AT 1 receptors. Specific ligand-receptor contacts for candesartan and telmisartan are altered in the active-state N111G- AT 1 receptors compared with the ground-state WT-AT 1 receptors, suggesting an explanation of their attenuated inverse agonist activity for the active state of AT 1 receptors. In contrast, interactions between eprosartan and N111G-AT 1 receptors were not significantly altered, and the inverse agonist activity of eprosartan was robust. Eprosartan may be a better therapeutic option than other ARBs. Comparative studies investigating eprosartan and other ARBs for the treatment of diseases caused by chronic, agonist-independent, AT 1 receptor activation are warranted. © 2018 The British Pharmacological Society.

  11. A Novel Non-Peptidic Agonist of the Ghrelin Receptor with Orexigenic Activity In vivo

    Science.gov (United States)

    Pastor-Cavada, Elena; Pardo, Leticia M.; Kandil, Dalia; Torres-Fuentes, Cristina; Clarke, Sarah L.; Shaban, Hamdy; McGlacken, Gerard P.; Schellekens, Harriet

    2016-11-01

    Loss of appetite in the medically ill and ageing populations is a major health problem and a significant symptom in cachexia syndromes, which is the loss of muscle and fat mass. Ghrelin is a gut-derived hormone which can stimulate appetite. Herein we describe a novel, simple, non-peptidic, 2-pyridone which acts as a selective agonist for the ghrelin receptor (GHS-R1a). The small 2-pyridone demonstrated clear agonistic activity in both transfected human cells and mouse hypothalamic cells with endogenous GHS-R1a receptor expression. In vivo tests with the hit compound showed significant increased food intake following peripheral administration, which highlights the potent orexigenic effect of this novel GHS-R1a receptor ligand.

  12. Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms

    Czech Academy of Sciences Publication Activity Database

    Randáková, Alena; Dolejší, Eva; Rudajev, Vladimír; Zimčík, Pavel; Doležal, Vladimír; El-Fakahany, E. E.; Jakubík, Jan

    2015-01-01

    Roč. 97, Jul 2015 (2015), s. 27-39 ISSN 1043-6618 R&D Projects: GA ČR(CZ) GA305/09/0681; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) EE2.3.30.0025 Institutional support: RVO:67985823 Keywords : muscarinic acetylcholine receptors * atypical agonists * xanomeline * activation mechanism Subject RIV: ED - Physiology Impact factor: 4.816, year: 2015

  13. Differential activation of G-proteins by μ-opioid receptor agonists

    Science.gov (United States)

    Saidak, Zuzana; Blake-Palmer, Katherine; Hay, Debbie L; Northup, John K; Glass, Michelle

    2006-01-01

    We investigated the ability of the activated μ-opioid receptor (MOR) to differentiate between myristoylated Gαi1 and GαoA type Gα proteins, and the maximal activity of a range of synthetic and endogenous agonists to activate each Gα protein. Membranes from HEK293 cells stably expressing transfected MOR were chaotrope extracted to denature endogenous G-proteins and reconstituted with specific purified G-proteins. The Gα subunits were generated in bacteria and were demonstrated to be recognised equivalently to bovine brain purified Gα protein by CB1 cannabinoid receptors. The ability of agonists to catalyse the MOR-dependent GDP/[35S]GTPγS exchange was then compared for Gαi1 and GαoA. Activation of MOR by DAMGO produced a high-affinity saturable interaction for GαoA (Km=20±1 nM) but a low-affinity interaction with Gαi1 (Km=116±12 nM). DAMGO, met-enkephalin and leucine-enkephalin displayed maximal Gα activation among the agonists evaluated. Endomorphins 1 and 2, methadone and β-endorphin activated both Gα to more than 75% of the maximal response, whereas fentanyl partially activated both G-proteins. Buprenorphine and morphine demonstrated a statistically significant difference between the maximal activities between Gαi1 and GαoA. Interestingly, DAMGO, morphine, endomorphins 1 and 2, displayed significant differences in the potencies for the activation of the two Gα. Differences in maximal activity and potency, for Gαi1 versus GαoA, are both indicative of agonist selective activation of G-proteins in response to MOR activation. These findings may provide a starting point for the design of drugs that demonstrate greater selectivity between these two G-proteins and therefore produce a more limited range of effects. PMID:16415903

  14. Platelet-activating factor receptor agonists mediate xeroderma pigmentosum A photosensitivity.

    Science.gov (United States)

    Yao, Yongxue; Harrison, Kathleen A; Al-Hassani, Mohammed; Murphy, Robert C; Rezania, Samin; Konger, Raymond L; Travers, Jeffrey B

    2012-03-16

    To date, oxidized glycerophosphocholines (Ox-GPCs) with platelet-activating factor (PAF) activity produced non-enzymatically have not been definitively demonstrated to mediate any known disease processes. Here we provide evidence that these Ox-GPCs play a pivotal role in the photosensitivity associated with the deficiency of the DNA repair protein xeroderma pigmentosum type A (XPA). It should be noted that XPA-deficient cells are known to have decreased antioxidant defenses. These studies demonstrate that treatment of human XPA-deficient fibroblasts with the pro-oxidative stressor ultraviolet B (UVB) radiation resulted in increased reactive oxygen species and PAF receptor (PAF-R) agonistic activity in comparison with gene-corrected cells. The UVB irradiation-generated PAF-R agonists were inhibited by antioxidants. UVB irradiation of XPA-deficient (Xpa-/-) mice also resulted in increased PAF-R agonistic activity and skin inflammation in comparison with control mice. The increased UVB irradiation-mediated skin inflammation and TNF-α production in Xpa-/- mice were blocked by systemic antioxidants and by PAF-R antagonists. Structural characterization of PAF-R-stimulating activity in UVB-irradiated XPA-deficient fibroblasts using mass spectrometry revealed increased levels of sn-2 short-chain Ox-GPCs along with native PAF. These studies support a critical role for PAF-R agonistic Ox-GPCs in the pathophysiology of XPA photosensitivity.

  15. Anti-tumor Activity of Toll-Like Receptor 7 Agonists

    Directory of Open Access Journals (Sweden)

    Huju Chi

    2017-05-01

    Full Text Available Toll-like receptors (TLRs are a class of pattern recognition receptors that play a bridging role in innate immunity and adaptive immunity. The activated TLRs not only induce inflammatory responses, but also elicit the development of antigen specific immunity. TLR7, a member of TLR family, is an intracellular receptor expressed on the membrane of endosomes. TLR7 can be triggered not only by ssRNA during viral infections, but also by immune modifiers that share a similar structure to nucleosides. Its powerful immune stimulatory action can be potentially used in the anti-tumor therapy. This article reviewed the anti-tumor activity and mechanism of TLR7 agonists that are frequently applied in preclinical and clinical investigations, and mainly focused on small synthetic molecules, including imiquimod, resiquimod, gardiquimod, and 852A, etc.

  16. The adenosine A2A receptor agonist CGS 21680 exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, M B; Fuxe, K; Werge, T

    2002-01-01

    The adenosine A2A receptor agonist CGS 21680 has shown effects similar to dopamine antagonists in behavioural assays in rats predictive for antipsychotic activity, without induction of extrapyramidal side-effects (EPS). In the present study, we examined whether this functional dopamine antagonism...... showed a functional anti-dopaminergic effect in Cebus apella monkeys without production of EPS. This further substantiates that adenosine A2A receptor agonists may have potential as antipsychotics with atypical profiles....

  17. Differential Regulation of Receptor Activation and Agonist Selectivity by Highly Conserved Tryptophans in the Nicotinic Acetylcholine Receptor Binding Site

    OpenAIRE

    Williams, Dustin K.; Stokes, Clare; Horenstein, Nicole A.; Papke, Roger L.

    2009-01-01

    We have shown previously that a highly conserved Tyr in the nicotinic acetylcholine receptor (nAChR) ligand-binding domain (LBD) (α7 Tyr188 or α4 Tyr195) differentially regulates the activity of acetylcholine (ACh) and the α7-selective agonist 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) in α4β2 and α7 nAChR. In this study, we mutated two highly conserved LBD Trp residues in human α7 and α4β2 and expressed the receptors in Xenopus laevis oocytes. α7 Re...

  18. Non-nucleotide Agonists Triggering P2X7 Receptor Activation and Pore Formation

    Directory of Open Access Journals (Sweden)

    Francesco Di Virgilio

    2018-02-01

    Full Text Available The P2X7 receptor (P2X7R is a ligand-gated plasma membrane ion channel belonging to the P2X receptor subfamily activated by extracellular nucleotides. General consensus holds that the physiological (and maybe the only agonist is ATP. However, scattered evidence generated over the last several years suggests that ATP might not be the only agonist, especially at inflammatory sites. Solid data show that NAD+ covalently modifies the P2X7R of mouse T lymphocytes, thus lowering the ATP threshold for activation. Other structurally unrelated agents have been reported to activate the P2X7R via a poorly understood mechanism of action: (a the antibiotic polymyxin B, possibly a positive allosteric P2X7R modulator, (b the bactericidal peptide LL-37, (c the amyloidogenic β peptide, and (d serum amyloid A. Some agents, such as Alu-RNA, have been suggested to activate the P2X7R acting on the intracellular N- or C-terminal domains. Mode of P2X7R activation by these non-nucleotide ligands is as yet unknown; however, these observations raise the intriguing question of how these different non-nucleotide ligands may co-operate with ATP at inflammatory or tumor sites. New information obtained from the cloning and characterization of the P2X7R from exotic mammalian species (e.g., giant panda and data from recent patch-clamp studies are strongly accelerating our understanding of P2X7R mode of operation, and may provide hints to the mechanism of activation of P2X7R by non-nucleotide ligands.

  19. Catalposide is a natural agonistic ligand of peroxisome proliferator-activated receptor

    International Nuclear Information System (INIS)

    Lee, Ji Hae; Jun, Hee-jin; Hoang, Minh-Hien; Jia, Yaoyao; Han, Xiang Hua; Lee, Dong-Ho; Lee, Hak-Ju; Hwang, Bang Yeon; Lee, Sung-Joon

    2012-01-01

    Highlights: ► Catalposide is a novel ligand for PPARα. ► Cell stimulated with catalposide improved fatty acid uptake, regulated target genes in fatty acid β-oxidation and synthesis. ► Catalposdie reduces hepatic triacylglycerides. ► Theses demonstrate catalposide could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: Peroxisome proliferator-activated receptor-alpha (PPARα) is a nuclear receptor that regulates the expression of genes related to cellular lipid uptake and oxidation. Thus, PPARα agonists may be important in the treatment of hypertriglyceridemia and hepatic steatosis. In this study, we demonstrated that catalposide is a novel natural PPARα agonist, identified from reporter gene assay-based activity screening with approximately 900 natural plant and seaweed extracts. Results of time-resolved fluorescence resonance energy transfer analyses suggested that the compound interacted directly with the ligand-binding domain of PPARα. Cultured hepatocytes stimulated with catalposide exhibited significantly reduced cellular triglyceride concentrations, by 21%, while cellular uptake of fatty acids was increased, by 70% (P < 0.05). Quantitative PCR analysis revealed that the increase in cellular fatty acid uptake was due to upregulation of fatty acid transporter protein-4 (+19% vs. the control) in cells stimulated with catalposide. Additionally, expression of genes related to fatty acid oxidation and high-density lipoprotein metabolism were upregulated, while that of genes related to fatty acid synthesis were suppressed. In conclusion, catalposide is hypolipidemic by activation of PPARα via a ligand-mediated mechanism that modulates the expression of in lipid metabolism genes in hepatocytes.

  20. Catalposide is a natural agonistic ligand of peroxisome proliferator-activated receptor-{alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Hae; Jun, Hee-jin; Hoang, Minh-Hien; Jia, Yaoyao [Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Department of Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Han, Xiang Hua [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Dong-Ho [Department of Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Hak-Ju [Division of Green Business Management, Department of Forest Resources Utilization, Korean Forest Research Institute, Seoul 130-712 (Korea, Republic of); Hwang, Bang Yeon, E-mail: byhwang@chungbuk.ac.kr [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Sung-Joon, E-mail: junelee@korea.ac.kr [Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Department of Biotechnology, Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Catalposide is a novel ligand for PPAR{alpha}. Black-Right-Pointing-Pointer Cell stimulated with catalposide improved fatty acid uptake, regulated target genes in fatty acid {beta}-oxidation and synthesis. Black-Right-Pointing-Pointer Catalposdie reduces hepatic triacylglycerides. Black-Right-Pointing-Pointer Theses demonstrate catalposide could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: Peroxisome proliferator-activated receptor-alpha (PPAR{alpha}) is a nuclear receptor that regulates the expression of genes related to cellular lipid uptake and oxidation. Thus, PPAR{alpha} agonists may be important in the treatment of hypertriglyceridemia and hepatic steatosis. In this study, we demonstrated that catalposide is a novel natural PPAR{alpha} agonist, identified from reporter gene assay-based activity screening with approximately 900 natural plant and seaweed extracts. Results of time-resolved fluorescence resonance energy transfer analyses suggested that the compound interacted directly with the ligand-binding domain of PPAR{alpha}. Cultured hepatocytes stimulated with catalposide exhibited significantly reduced cellular triglyceride concentrations, by 21%, while cellular uptake of fatty acids was increased, by 70% (P < 0.05). Quantitative PCR analysis revealed that the increase in cellular fatty acid uptake was due to upregulation of fatty acid transporter protein-4 (+19% vs. the control) in cells stimulated with catalposide. Additionally, expression of genes related to fatty acid oxidation and high-density lipoprotein metabolism were upregulated, while that of genes related to fatty acid synthesis were suppressed. In conclusion, catalposide is hypolipidemic by activation of PPAR{alpha} via a ligand-mediated mechanism that modulates the expression of in lipid metabolism genes in hepatocytes.

  1. Agonistic activity of tamoxifen, a selective estrogen-receptor modulator (SERM), on arthritic ovariectomized mice

    Science.gov (United States)

    Silva, L.A.S.; Felix, F.B.; Araujo, J.M.D.; Souza, E.V.; Camargo, E.A.; Grespan, R.

    2017-01-01

    Arthritis is positively associated with the decline of sex hormones, especially estrogen. Tamoxifen (TMX) is a selective estrogen receptor modulator, possessing agonist or antagonistic activity in different tissues. Thus, the objective of this study was to investigate the effect of TMX on the zymosan-induced arthritis model. Female Swiss normal and ovariectomized (OVX) mice were divided into groups and treated for five days with TMX (0.3, 0.9 or 2.7 mg/kg) or 17-β-estradiol (E2, 50 µg/kg). On the fifth day, arthritis was induced and 4 h later, leukocyte migration into joint cavities was evaluated. The neutrophil migration in OVX animals, but not in normal mice, treated with TMX (all tested doses) was significantly decreased compared with mice that received the vehicle (P≤0.05). Similarly, this effect was also demonstrated in the E2-treated group. Therefore, the present study demonstrates that TMX presented agonist effects in inhibiting neutrophil migration and preventing arthritis progression in OVX mice. PMID:29160416

  2. Adrenaline release by the 5-HT1A receptor agonist 8-OH-DPAT is partly responsible for pituitary activation

    NARCIS (Netherlands)

    Korte, S.M; Buwalda, B; Bohus, B.G J; de Kloet, E.R

    1996-01-01

    In male Wistar rats the effect of adrenalectomy on pituitary activation by the 5-HT1A receptor agonist. 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), was studied. Rats were injected intravenously with 8-OH-DPAT (0.10 mg/kg) in their home cages. Blood samples were withdrawn from freely moving

  3. Ghrelin receptor inverse agonists: identification of an active peptide core and its interaction epitopes on the receptor

    DEFF Research Database (Denmark)

    Holst, Birgitte; Lang, Manja; Brandt, Erik

    2006-01-01

    [D-Arg1,D-Phe5,D-Trp7,9,Leu11]Substance P functions as a low-potency antagonist but a high-potency full inverse agonist on the ghrelin receptor. Through a systematic deletion and substitution analysis of this peptide, the C-terminal carboxyamidated pentapeptide wFwLX was identified as the core...... structure, which itself displayed relatively low inverse agonist potency. Mutational analysis at 17 selected positions in the main ligand-binding crevice of the ghrelin receptor demonstrated that ghrelin apparently interacts only with residues in the middle part of the pocket [i.e., between transmembrane...... upon both AspII:20 and GluIII:09. The identified pharmacophore can possibly serve as the basis for targeted discovery of also nonpeptide inverse agonists for the ghrelin receptor....

  4. G protein- and agonist-bound serotonin 5-HT2A receptor model activated by steered molecular dynamics simulations

    DEFF Research Database (Denmark)

    Ísberg, Vignir; Balle, Thomas; Sander, Tommy

    2011-01-01

    molecular dynamics (MD) simulations. The driving force for the transformation was the addition of several known intermolecular and receptor interhelical hydrogen bonds enforcing the necessary helical and rotameric movements. Subsquent MD simulations without constraints confirmed the stability......A 5-HT(2A) receptor model was constructed by homology modeling based on the ß(2)-adrenergic receptor and the G protein-bound opsin crystal structures. The 5-HT(2A) receptor model was transferred into an active conformation by an agonist ligand and a G(aq) peptide in four subsequent steered...

  5. Peroxisome proliferator-activated receptor-gamma agonists suppress tissue factor overexpression in rat balloon injury model with paclitaxel infusion.

    Directory of Open Access Journals (Sweden)

    Jun-Bean Park

    Full Text Available The role and underlying mechanisms of rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-γ agonist, on myocardial infarction are poorly understood. We investigated the effects of this PPAR-γ agonist on the expression of tissue factor (TF, a primary molecule for thrombosis, and elucidated its underlying mechanisms. The PPAR-γ agonist inhibited TF expression in response to TNF-α in human umbilical vein endothelial cells, human monocytic leukemia cell line, and human umbilical arterial smooth muscle cells. The overexpression of TF was mediated by increased phosphorylation of mitogen-activated protein kinase (MAPK, which was blocked by the PPAR-γ agonist. The effective MAPK differed depending on each cell type. Luciferase and ChIP assays showed that transcription factor, activator protein-1 (AP-1, was a pivotal target of the PPAR-γ agonist to lower TF transcription. Intriguingly, two main drugs for drug-eluting stent, paclitaxel or rapamycin, significantly exaggerated thrombin-induced TF expression, which was also effectively blocked by the PPAR-γ agonist in all cell types. This PPAR-γ agonist did not impair TF pathway inhibitor (TFPI in three cell types. In rat balloon injury model (Sprague-Dawley rats, n = 10/group with continuous paclitaxel infusion, the PPAR-γ agonist attenuated TF expression by 70±5% (n = 4; P<0.0001 in injured vasculature. Taken together, rosiglitazone reduced TF expression in three critical cell types involved in vascular thrombus formation via MAPK and AP-1 inhibitions. Also, this PPAR-γ agonist reversed the paclitaxel-induced aggravation of TF expression, which suggests a possibility that the benefits might outweigh its risks in a group of patients with paclitaxel-eluting stent implanted.

  6. Involvement of the Retinoid X Receptor Ligand in the Anti-Inflammatory Effect Induced by Peroxisome Proliferator-Activated Receptor Agonist In Vivo

    Directory of Open Access Journals (Sweden)

    Atsuki Yamamoto

    2011-01-01

    Full Text Available Peroxisome proliferator-activated receptor γ (PPARγ forms a heterodimeric DNA-binding complex with retinoid X receptors (RXRs. It has been reported that the effect of the PPAR agonist is reduced in hepatocyte RXR-deficient mice. Therefore, it is suggested that the endogenous RXR ligand is involved in the PPARγ agonist-induced anti-inflammatory effect. However, the participation of the RXR ligand in the PPARγ-induced anti-inflammatory effect is unknown. Here, we investigated the influence of RXR antagonist on the anti-inflammatory effect of PPARγ agonist pioglitazone in carrageenan test. In addition, we also examined the influence of PPAR antagonist on the anti-inflammatory effect induced by RXR agonist NEt-3IP. The RXR antagonist suppressed the antiedema effect of PPARγ agonist. In addition, the anti-inflammatory effect of RXR agonist was suppressed by PPARγ antagonist. PPARγ agonist-induced anti-inflammatory effects were reversed by the RXR antagonist. Thus, we showed that the endogenous RXR ligand might contribute to the PPARγ agonist-induced anti-inflammatory effect.

  7. Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

    Science.gov (United States)

    Young, R. B.; Bridge, K. Y.

    2003-01-01

    Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate CAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of CAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of CAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of CAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of CAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of CAMP by either epinephrine or isoproterenol.

  8. Adaptability and selectivity of human peroxisome proliferator-activated receptor (PPAR) pan agonists revealed from crystal structures

    International Nuclear Information System (INIS)

    Oyama, Takuji; Toyota, Kenji; Waku, Tsuyoshi; Hirakawa, Yuko; Nagasawa, Naoko; Kasuga, Jun-ichi; Hashimoto, Yuichi; Miyachi, Hiroyuki; Morikawa, Kosuke

    2009-01-01

    The structures of the ligand-binding domains (LBDs) of human peroxisome proliferator-activated receptors (PPARα, PPARγ and PPARδ) in complexes with a pan agonist, an α/δ dual agonist and a PPARδ-specific agonist were determined. The results explain how each ligand is recognized by the PPAR LBDs at an atomic level. Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family, which is defined as transcriptional factors that are activated by the binding of ligands to their ligand-binding domains (LBDs). Although the three PPAR subtypes display different tissue distribution patterns and distinct pharmacological profiles, they all are essentially related to fatty-acid and glucose metabolism. Since the PPARs share similar three-dimensional structures within the LBDs, synthetic ligands which simultaneously activate two or all of the PPARs could be potent candidates in terms of drugs for the treatment of abnormal metabolic homeostasis. The structures of several PPAR LBDs were determined in complex with synthetic ligands, derivatives of 3-(4-alkoxyphenyl)propanoic acid, which exhibit unique agonistic activities. The PPARα and PPARγ LBDs were complexed with the same pan agonist, TIPP-703, which activates all three PPARs and their crystal structures were determined. The two LBD–ligand complex structures revealed how the pan agonist is adapted to the similar, but significantly different, ligand-binding pockets of the PPARs. The structures of the PPARδ LBD in complex with an α/δ-selective ligand, TIPP-401, and with a related δ-specific ligand, TIPP-204, were also determined. The comparison between the two PPARδ complexes revealed how each ligand exhibits either a ‘dual selective’ or ‘single specific’ binding mode

  9. Identification of novel peroxisome proliferator-activated receptor-gamma (PPARγ) agonists using molecular modeling method

    Science.gov (United States)

    Gee, Veronica M. W.; Wong, Fiona S. L.; Ramachandran, Lalitha; Sethi, Gautam; Kumar, Alan Prem; Yap, Chun Wei

    2014-11-01

    Peroxisome proliferator-activated receptor-gamma (PPARγ) plays a critical role in lipid and glucose homeostasis. It is the target of many drug discovery studies, because of its role in various disease states including diabetes and cancer. Thiazolidinediones, a synthetic class of agents that work by activation of PPARγ, have been used extensively as insulin-sensitizers for the management of type 2 diabetes. In this study, a combination of QSAR and docking methods were utilised to perform virtual screening of more than 25 million compounds in the ZINC library. The QSAR model was developed using 1,517 compounds and it identified 42,378 potential PPARγ agonists from the ZINC library, and 10,000 of these were selected for docking with PPARγ based on their diversity. Several steps were used to refine the docking results, and finally 30 potentially highly active ligands were identified. Four compounds were subsequently tested for their in vitro activity, and one compound was found to have a K i values of <5 μM.

  10. Subtype selective kainic acid receptor agonists

    DEFF Research Database (Denmark)

    Bunch, Lennart; Krogsgaard-Larsen, Povl

    2009-01-01

    (S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors (m......GluRs). Within the iGluRs, five subtypes (KA1, KA2, iGluR5-7) show high affinity and express full agonist activity upon binding of the naturally occurring amino acid kainic acid (KA). Thus these receptors have been named the KA receptors. This review describes all-to our knowledge-published KA receptor agonists...

  11. A DFT approach to discriminate the antagonist and partial agonist activity of ligands binding to the NMDA receptor

    Science.gov (United States)

    Haslak, Zeynep Pinar; Bozkurt, Esra; Dutagaci, Bercem; De Proft, Frank; Aviyente, Viktorya; De Vleeschouwer, Freija

    2018-02-01

    The activation of N-methyl-D-aspartate receptors is found to be intimately associated with neurodegenerative diseases which make them promising therapeutic targets. Despite the significantly increasing multidisciplinary interests centred on this ionotropic channel, design of new ligands with intended functional activity remains a great challenge. In this article, a computational study based on density functional theory is presented to understand the structural factors of ligands determining their function as antagonists and partial agonists. With this aim, the GluN1 subunit is chosen as being one of the essential components in the activation mechanism, and quantum chemical calculations are implemented for 30 antagonists and 30 partial agonists known to bind to this subunit with different binding affinities. Several quantum chemical descriptors are investigated which might unlock the difference between antagonists and partial agonists.

  12. Medium chain fatty acids are selective peroxisome proliferator activated receptor (PPAR γ activators and pan-PPAR partial agonists.

    Directory of Open Access Journals (Sweden)

    Marcelo Vizoná Liberato

    Full Text Available Thiazolidinediones (TZDs act through peroxisome proliferator activated receptor (PPAR γ to increase insulin sensitivity in type 2 diabetes (T2DM, but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of PPARγ ligand binding domain (LBD and found that the ligand binding pocket (LBP is occupied by bacterial medium chain fatty acids (MCFAs. We verified that MCFAs (C8-C10 bind the PPARγ LBD in vitro and showed that they are low-potency partial agonists that display assay-specific actions relative to TZDs; they act as very weak partial agonists in transfections with PPARγ LBD, stronger partial agonists with full length PPARγ and exhibit full blockade of PPARγ phosphorylation by cyclin-dependent kinase 5 (cdk5, linked to reversal of adipose tissue insulin resistance. MCFAs that bind PPARγ also antagonize TZD-dependent adipogenesis in vitro. X-ray structure B-factor analysis and molecular dynamics (MD simulations suggest that MCFAs weakly stabilize C-terminal activation helix (H 12 relative to TZDs and this effect is highly dependent on chain length. By contrast, MCFAs preferentially stabilize the H2-H3/β-sheet region and the helix (H 11-H12 loop relative to TZDs and we propose that MCFA assay-specific actions are linked to their unique binding mode and suggest that it may be possible to identify selective PPARγ modulators with useful clinical profiles among natural products.

  13. α(1) adrenergic receptor agonist, phenylephrine, actively contracts early rat rib fracture callus ex vivo.

    Science.gov (United States)

    McDonald, Stuart J; Dooley, Philip C; McDonald, Aaron C; Djouma, Elvan; Schuijers, Johannes A; Ward, Alex R; Grills, Brian L

    2011-05-01

    Early, soft fracture callus that links fracture ends together is smooth muscle-like in nature. We aimed to determine if early fracture callus could be induced to contract and relax ex vivo by similar pathways to smooth muscle, that is, contraction via α(1) adrenergic receptor (α(1) AR) activation with phenylephrine (PE) and relaxation via β(2) adrenergic receptor (β(2) AR) stimulation with terbutaline. A sensitive force transducer quantified 7 day rat rib fracture callus responses in modified Krebs-Henseliet (KH) solutions. Unfractured ribs along with 7, 14, and 21 day fracture calluses were analyzed for both α(1) AR and β(2) AR gene expression using qPCR, whilst 7 day fracture callus was examined via immunohistochemistry for both α(1) AR and β(2) AR- immunoreactivity. In 7 day callus, PE (10(-6)  M) significantly induced an increase in force that was greater than passive force generated in calcium-free KH (n = 8, mean 51% increase, 95% CI: 26-76%). PE-induced contractions in calluses were attenuated by the α(1) AR antagonist, prazosin (10(-6)  M; n = 7, mean 5% increase, 95% CI: 2-11%). Terbutaline did not relax callus. Gene expression of α(1) ARs was constant throughout fracture healing; however, β(2) AR expression was down-regulated at 7 days compared to unfractured rib (p contract. We propose that increased concentrations of α(1) AR agonists such as noradrenaline may tonically contract callus in vivo to promote osteogenesis. Copyright © 2010 Orthopaedic Research Society.

  14. Blockade of alcohol's amnestic activity in humans by an alpha5 subtype benzodiazepine receptor inverse agonist.

    Science.gov (United States)

    Nutt, David J; Besson, Marie; Wilson, Susan J; Dawson, Gerard R; Lingford-Hughes, Anne R

    2007-12-01

    Alcohol produces many subjective and objective effects in man including pleasure, sedation, anxiolysis, plus impaired eye movements and memory. In human volunteers we have used a newly available GABA-A/benzodiazepine receptor inverse agonist that is selective for the alpha5 subtype (a5IA) to evaluate the role of this subtype in mediating these effects of alcohol on the brain. After pre-treatment with a5IA, we found almost complete blockade of the marked impairment caused by alcohol (mean breath concentration 150mg/100ml) of word list learning and partial but non-significant reversal of subjective sedation without effects on other measures such as intoxication, liking, and slowing of eye movements. This action was not due to alterations in alcohol kinetics and so provides the first proof of concept that selectively decreasing GABA-A receptor function at a specific receptor subtype can offset some actions of alcohol in humans. It also supports growing evidence for a key role of the alpha5 subtype in memory. Inverse agonists at other GABA-A receptor subtypes may prove able to reverse other actions of alcohol, and so offer a new approach to understanding the actions of alcohol in the human brain and in the treatment of alcohol related disorders in humans.

  15. Hepatocellular proliferation in response to agonists of peroxisome proliferator-activated receptor alpha: a role for kupffer cells?

    Directory of Open Access Journals (Sweden)

    Cunningham Michael

    2006-01-01

    Full Text Available Abstract Background It has been proposed that PPARα agonists stimulate Kupffer cells in rodents which in turn, release mitogenic factors leading to hepatic hyperplasia, and eventually cancer. However, Kupffer cells do not express PPARα receptors, and PPARα agonists stimulate hepatocellular proliferation in both TNFα- and TNFα receptor-null mice, casting doubt on the involvement of Kupffer cells in the mitogenic response to PPARα agonists. This study was therefore designed to investigate whether the PPARα agonist PFOA and the Kupffer cell inhibitor methylpalmitate produce opposing effects on hepatocellular proliferation and Kupffer cell activity in vivo, in a manner that would implicate these cells in the mitogenic effects of PPARα agonists. Methods Male Sprague-Dawley rats were treated intravenously via the tail vein with methylpalmitate 24 hrs prior to perfluorooctanoic acid (PFOA, and were sacrificed 24 hrs later, one hr after an intraperitoneal injection of bromodeoxyuridine (BrdU. Sera were analyzed for TNFα and IL-1β. Liver sections were stained immunohistochemically and quantified for BrdU incorporated into DNA. Results Data show that PFOA remarkably stimulated hepatocellular proliferation in the absence of significant changes in the serum levels of either TNFα or IL-1β. In addition, methylpalmitate did not alter the levels of these mitogens in PFOA-treated animals, despite the fact that it significantly blocked the hepatocellular proliferative effect of PFOA. Correlation between hepatocellular proliferation and serum levels of TNFα or IL-1β was extremely poor. Conclusion It is unlikely that mechanisms involving Kupffer cells play an eminent role in the hepatic hyperplasia, and consequently hepatocarcinogenicity attributed to PPARα agonists. This conclusion is based on the above mentioned published data and the current findings showing animals treated with PFOA alone or in combination with methylpalmitate to have similar

  16. Conformational variability of the glycine receptor M2 domain in response to activation by different agonists

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Dibas, Mohammed I; Lester, Henry A

    2007-01-01

    change. Although taurine and beta-alanine were weak partial agonists at the alpha1R19'C glycine receptor, they induced large fluorescence changes. Propofol, which drastically enhanced these currents, did not induce a glycine-like blue shift in the spectral emission peak. The inhibitors strychnine...... and picrotoxin elicited fluorescence and current changes as expected for a competitive antagonist and an open channel blocker, respectively. Glycine and taurine (or beta-alanine) also produced an increase and a decrease, respectively, in the fluorescence of a label attached to the nearby L22'C residue. Thus...

  17. A retinoic acid receptor β2 agonist reduces hepatic stellate cell activation in nonalcoholic fatty liver disease.

    Science.gov (United States)

    Trasino, Steven E; Tang, Xiao-Han; Jessurun, Jose; Gudas, Lorraine J

    2016-10-01

    Hepatic stellate cells (HSCs) are an important cellular target for the development of novel pharmacological therapies to prevent and treat nonalcoholic fatty liver diseases (NAFLD). Using a high fat diet (HFD) model of NAFLD, we sought to determine if synthetic selective agonists for retinoic acid receptor β2 (RARβ2) and RARγ can mitigate HSC activation and HSC relevant signaling pathways during early stages of NAFLD, before the onset of liver injury. We demonstrate that the highly selective RARβ2 agonist, AC261066, can reduce the activation of HSCs, marked by decreased HSC expression of α-smooth muscle actin (α-SMA), in mice with HFD-induced NAFLD. Livers of HFD-fed mice treated with AC261066 exhibited reduced steatosis, oxidative stress, and expression of pro-inflammatory mediators, such as tumor necrosis factor-alpha (TNFα), interleukin 1β (IL-1β), and monocyte chemotactic protein-1 (MCP-1). Kupffer cell (macrophage) expression of transforming growth factor-β1 (TGF-β1), which plays a critical role in early HSC activation, was markedly reduced in AC261066-treated, HFD-fed mice. In contrast, HFD-fed mice treated with an RARγ agonist (CD1530) showed no decreases in steatosis, HSC activation, or Kupffer cell TGF-β1 levels. In conclusion, our data demonstrate that RARβ2 is an attractive target for development of NAFLD therapies. • Hepatic stellate cells (HSCs) are an important pharmacological target for the prevention of nonalcoholic fatty liver diseases (NAFLD). • Retinoids and retinoic acid receptors (RARs) possess favorable metabolic modulating properties. • We show that an agonist for retinoic acid receptor-β2 (RARβ2), but not RARγ, mitigates HSC activation and NAFLD.

  18. Essential oils of culinary herbs and spices display agonist and antagonist activities at human aryl hydrocarbon receptor AhR.

    Science.gov (United States)

    Bartoňková, Iveta; Dvořák, Zdeněk

    2018-01-01

    Essential oils (EOs) of culinary herbs and spices are used to flavor, color and preserve foods and drinks. Dietary intake of EOs is significant, deserving an attention of toxicologists. We examined the effects of 31 EOs of culinary herbs and spices on the transcriptional activity of human aryl hydrocarbon receptor (AhR), which is a pivotal xenobiotic sensor, having also multiple roles in human physiology. Tested EOs were sorted out into AhR-inactive ones (14 EOs) and AhR-active ones, including full agonists (cumin, jasmine, vanilla, bay leaf), partial agonists (cloves, dill, thyme, nutmeg, oregano) and antagonists (tarragon, caraway, turmeric, lovage, fennel, spearmint, star anise, anise). Major constituents (>10%) of AhR-active EOs were studied in more detail. We identified AhR partial agonists (carvacrol, ligustilide, eugenol, eugenyl acetate, thymol, ar-turmerone) and antagonists (trans-anethole, butylidine phtalide, R/S-carvones, p-cymene), which account for AhR-mediated activities of EOs of fennel, anise, star anise, caraway, spearmint, tarragon, cloves, dill, turmeric, lovage, thyme and oregano. We also show that AhR-mediated effects of some individual constituents of EOs differ from those manifested in mixtures. In conclusion, EOs of culinary herbs and spices are agonists and antagonists of human AhR, implying a potential for food-drug interactions and interference with endocrine pathways. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Endogenous Receptor Agonists: Resolving Inflammation

    Directory of Open Access Journals (Sweden)

    Gerhard Bannenberg

    2007-01-01

    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.

  20. Promotion of Wound Healing by an Agonist of Adenosine A2A Receptor Is Dependent on Tissue Plasminogen Activator.

    Science.gov (United States)

    Montesinos, M Carmen; Desai-Merchant, Avani; Cronstein, Bruce N

    2015-12-01

    Impaired wound healing, as it occurs in diabetes mellitus or long-term corticoid treatment, is commonly associated with disability, diminished quality of life, and high economic costs. Selective agonists of the A2A receptor subtype of adenosine, an endogenous regulator of inflammation, promote tissue repair in animal models, both healthy and with impaired healing. Plasmin-mediated proteolysis of fibrin and other matrix proteins is essential for cell migration at sites of injury. Since adenosine A2A receptor activation increases plasminogen activator release from macrophages and mast cells, we studied the effect of a selective agonist, CGS-21680, on full-thickness excisional wound closure in wild-type, urokinase plasminogen activator (uPA)-deficient, and tissue plasminogen activator (tPA)-deficient mice. Wound closure was impaired in tPA- and uPA-deficient mice as compared with wild-type mice, and topical application of CGS-21680 significantly increased the rate at which wounds closed in wild-type mice and uPA-deficient mice, but not in tPA-deficient mice. Immunostaining of tissue sections showed that tPA was present in endothelial cells and histiocytes by day 3 post-wound and also by day 6. In contrast, uPA was more prominent in these cell types only by day 6 post-wound. Our results confirm that plasminogen activation contributes to wound repair and are consistent with the hypothesis that adenosine A2A receptor activation promotes wound closure by a mechanism that depends upon tPA, but not uPA. Moreover, our results suggest that topical adenosine A2A receptor agonists may be useful in promotion of wound closure in patients with impaired wound healing.

  1. Pharmacological profile of DA-6886, a novel 5-HT4 receptor agonist to accelerate colonic motor activity in mice.

    Science.gov (United States)

    Lee, Min Jung; Cho, Kang Hun; Park, Hyun Min; Sung, Hyun Jung; Choi, Sunghak; Im, Weonbin

    2014-07-15

    DA-6886, the gastrointestinal prokinetic benzamide derivative is a novel 5-HT4 receptor agonist being developed for the treatment of constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study was to characterize in vitro and in vivo pharmacological profile of DA-6886. We used various receptor binding assay, cAMP accumulation assay, organ bath experiment and colonic transit assay in normal and chemically constipated mice. DA-6886 exhibited high affinity and selectivity to human 5-HT4 receptor splice variants, with mean pKi of 7.1, 7.5, 7.9 for the human 5-HT4a, 5-HT4b and 5-HT4d, respectively. By contrast, DA-6886 did not show significant affinity for several receptors including dopamine D2 receptor, other 5-HT receptors except for 5-HT2B receptor (pKi value of 6.2). The affinity for 5-HT4 receptor was translated into functional agonist activity in Cos-7 cells expressing 5-HT4 receptor splice variants. Furthermore, DA-6886 induced relaxation of the rat oesophagus preparation (pEC50 value of 7.4) in a 5-HT4 receptor antagonist-sensitive manner. The evaluation of DA-6886 in CHO cells expressing hERG channels revealed that it inhibited hERG channel current with an pIC50 value of 4.3, indicating that the compound was 1000-fold more selective for the 5-HT4 receptor over hERG channels. In the normal ICR mice, oral administration of DA-6886 (0.4 and 2mg/kg) resulted in marked stimulation of colonic transit. Furthermore, in the loperamide-induced constipation mouse model, 2mg/kg of DA-6886 significantly improved the delay of colonic transit, similar to 10mg/kg of tegaserod. Taken together, DA-6886 is a highly potent and selective 5-HT4 receptor agonist to accelerate colonic transit in mice, which might be therapeutic agent having a favorable safety profile in the treatment of gastrointestinal motor disorders such as IBS-C and chronic constipation. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Correction for Inhibition Leads to an Allosteric Co-Agonist Model for Pentobarbital Modulation and Activation of α1β3γ2L GABAA Receptors.

    Directory of Open Access Journals (Sweden)

    Alexis M Ziemba

    Full Text Available Pentobarbital, like propofol and etomidate, produces important general anesthetic effects through GABAA receptors. Photolabeling also indicates that pentobarbital binds to some of the same sites where propofol and etomidate act. Quantitative allosteric co-agonist models for propofol and etomidate account for modulatory and agonist effects in GABAA receptors and have proven valuable in establishing drug site characteristics and for functional analysis of mutants. We therefore sought to establish an allosteric co-agonist model for pentobarbital activation and modulation of α1β3γ2L receptors, using a novel approach to first correct pentobarbital activation data for inhibitory effects in the same concentration range.Using oocyte-expressed α1β3γ2L GABAA receptors and two-microelectrode voltage-clamp, we quantified modulation of GABA responses by a low pentobarbital concentration and direct effects of high pentobarbital concentrations, the latter displaying mixed agonist and inhibitory effects. We then isolated and quantified pentobarbital inhibition in activated receptors using a novel single-sweep "notch" approach, and used these results to correct steady-state direct activation for inhibition.Combining results for GABA modulation and corrected direct activation, we estimated receptor open probability and optimized parameters for a Monod-Wyman-Changeux allosteric co-agonist model. Inhibition by pentobarbital was consistent with two sites with IC50s near 1 mM, while co-agonist model parameters suggest two allosteric pentobarbital agonist sites characterized by KPB ≈ 5 mM and high efficacy. The results also indicate that pentobarbital may be a more efficacious agonist than GABA.Our novel approach to quantifying both inhibitory and co-agonist effects of pentobarbital provides a basis for future structure-function analyses of GABAA receptor mutations in putative pentobarbital binding sites.

  3. Rational screening of peroxisome proliferator-activated receptoragonists from natural products: potential therapeutics for heart failure.

    Science.gov (United States)

    Chen, Rui; Wan, Jing; Song, Jing; Qian, Yan; Liu, Yong; Gu, Shuiming

    2017-12-01

    Peroxisome proliferator-activated receptor-γ (PPARγ) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. Activation of PPARγ pathway has been shown to enhance fatty acid oxidation, improve endothelial cell function, and decrease myocardial fibrosis in heart failure. Thus, the protein has been raised as an attractive target for heart failure therapy. This work attempted to discover new and potent PPARγ agonists from natural products using a synthetic strategy of computer virtual screening and transactivation reporter assay. A large library of structurally diverse, drug-like natural products was compiled, from which those with unsatisfactory pharmacokinetic profile and/or structurally redundant compounds were excluded. The binding mode of remaining candidates to PPARγ ligand-binding domain (LBD) was computationally modelled using molecular docking and their relative binding potency was ranked by an empirical scoring scheme. Consequently, eight commercially available hits with top scores were selected and their biological activity was determined using a cell-based reporter-gene assay. Four natural product compounds, namely ZINC13408172, ZINC4292805, ZINC44179 and ZINC901461, were identified to have high or moderate agonistic potency against human PPARγ with EC 50 values of 0.084, 2.1, 0.35 and 5.6 μM, respectively, which are comparable to or even better than that of the approved PPARγ full agonists pioglitazone (EC 50  =   0.16 μM) and rosiglitazone (EC 50  =   0.034 μM). Hydrophobic interactions and van der Waals contacts are the primary chemical forces to stabilize the complex architecture of PPARγ LBD domain with these agonist ligands, while few hydrogen bonds, salt bridges and/or π-π stacking at the complex interfaces confer selectivity and specificity for the domain-agonist recognition. The integrated in vitro-in silico screening strategy can be successfully applied to rational discovery of

  4. Muscarinic Receptor Agonists and Antagonists

    Directory of Open Access Journals (Sweden)

    David R. Kelly

    2001-02-01

    Full Text Available A comprehensive review of pharmacological and medical aspects of the muscarinic class of acetylcholine agonists and antagonists is presented. The therapeutic benefits of achieving receptor subtype selectivity are outlined and applications in the treatment of Alzheimer’s disease are discussed. A selection of chemical routes are described, which illustrate contemporary methodology for the synthesis of chiral medicinal compounds (asymmetric synthesis, chiral pool, enzymes. Routes to bicyclic intrannular amines and intramolecular Diels-Alder reactions are highlighted.

  5. Small-molecule AT2 receptor agonists

    DEFF Research Database (Denmark)

    Hallberg, Mathias; Sumners, Colin; Steckelings, U Muscha

    2018-01-01

    The discovery of the first selective, small-molecule ATR receptor (AT2R) agonist compound 21 (C21) (8) that is now extensively studied in a large variety of in vitro and in vivo models is described. The sulfonylcarbamate derivative 8, encompassing a phenylthiofen scaffold is the drug-like agonist...... with the highest affinity for the AT2R reported to date (Ki = 0.4 nM). Structure-activity relationships (SAR), regarding different biaryl scaffolds and functional groups attached to these scaffolds and with a particular focus on the impact of various para substituents displacing the methylene imidazole group of 8......, are discussed. Furthermore, the consequences of migration of the methylene imidazole group and presumed structural requirements for ligands that are aimed as AT2R agonists (e.g. 8) or AT2R antagonists (e.g. 9), respectively, are briefly addressed. A summary of the pharmacological actions of C21 (8) is also...

  6. Elafibranor, an Agonist of the Peroxisome Proliferator-Activated Receptor-alpha and -delta, Induces Resolution of Nonalcoholic Steatohepatitis Without Fibrosis Worsening

    NARCIS (Netherlands)

    Ratziu, V.; Harrison, S.A.; Francque, S.; Bedossa, P.; Lehert, P.; Serfaty, L.; Romero-Gomez, M.; Boursier, J.; Abdelmalek, M.; Caldwell, S.; Drenth, J.P.; Anstee, Q.M.; Hum, D.; Hanf, R.; Roudot, A.; Megnien, S.; Staels, B.; Sanyal, A.

    2016-01-01

    BACKGROUND & AIMS: Elafibranor is an agonist of the peroxisome proliferator-activated receptor-alpha and peroxisome proliferator-activated receptor-delta. Elafibranor improves insulin sensitivity, glucose homeostasis, and lipid metabolism and reduces inflammation. We assessed the safety and efficacy

  7. Efficacy of peroxisome proliferator activated receptor agonist in the treatment of virus-associated haemophagocytic syndrome in a rabbit model.

    Science.gov (United States)

    Hsieh, Wen-Chuan; Lan, Bau-Shin; Chen, Yi-Ling; Chang, Yao; Chuang, Huai-Chia; Su, Ih-Jen

    2010-01-01

    Virus-associated haemophagocytic syndrome (VAHS) is a fatal complication of viral infections, such as Epstein-Barr virus and H5N1 influenza, that results from macrophage activation and pro inflammatory cytokine injuries. The high comorbidity and mortality of current therapy urgently demands an ideal agent based on VAHS pathogenesis. Peroxisome proliferator activated receptor (PPAR) agonists, regulators of metabolic syndrome, can exhibit immunomodulatory effects on macrophage activation and cytokine secretion. In this study, we adopted rosiglitazone, a PPAR-gamma agonist, for VAHS control in a Herpesvirus papio (HVP)-infected rabbit model. Various doses of rosiglitazone were orally administered to rabbits on day 7 or day 20 after intravenous challenge with 5 x 10(7) copies of HVP. The rabbits that received 4 mg/day rosiglitazone had significantly increased survival when treated at an early stage of infection (P<0.01), whereas a higher dose (8 mg/day) was required at the advanced stage of the disease (P<0.05). All rosiglitazone-treated rabbits had significantly improved laboratory parameters and plasma tumour necrosis factor-alpha levels. Importantly, rosiglitazone could also inhibit viral replication in vitro and in vivo. PPAR agonists could represent a potentially new agent for the therapy of VAHS.

  8. Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy.

    Science.gov (United States)

    Jakubík, J; Janíčková, H; El-Fakahany, E E; Doležal, V

    2011-03-01

    Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor. Agonists displayed biphasic competition curves with the antagonist [³H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [³H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from G(i/o) G-proteins but only its dissociation from G(s/olf) G-proteins. These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of G(i/o) versus G(s/olf) G-proteins that are not identified by conventional GTPγS binding. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  9. D-Arg0-Bradykinin-Arg-Arg, a Latent Vasoactive Bradykinin B2 Receptor Agonist Metabolically Activated by Carboxypeptidases

    Directory of Open Access Journals (Sweden)

    Hélène Bachelard

    2018-03-01

    Full Text Available We previously reported hypotensive and vasodilator effects from C-terminally extended bradykinin (BK sequences that behave as B2 receptor (B2R agonists activated by vascular or plasma peptidases. D-Arg0-BK-Arg-Arg (r-BK-RR is a novel prodrug peptide hypothetically activated by two catalytic cycles of Arg-carboxypeptidases (CPs to release the direct agonist D-Arg0-BK. N-terminally extending the BK sequence with D-Arg0 in the latter peptide was meant to block the second kinin inactivation pathway in importance, aminopeptidase P. The affinity of r-BK and r-BK-RR for recombinant B2R was assessed using a [3H]BK binding displacement assay. Their pharmacology was evaluated in human isolated umbilical vein, a contractile bioassay for the B2R, in a morphological assay involving the endocytosis of B2R-green fusion protein (GFP and in anesthetized rats instrumented to record hemodynamic responses to bolus intravenous injection of both peptides. r-BK exhibited an affinity equal to that of BK for the rat B2R, while r-BK-RR was 61-fold less potent. In the vein and the B2R-GFP internalization assay, r-BK was a direct agonist unaffected by the blockade of angiotensin converting enzyme (ACE with enalaprilat, or Arg-CPs with Plummer’s inhibitor. However, the in vitro effects of r-BK-RR were reduced by these inhibitors, more so by enalaprilat. In anesthetized rats, r-BK and r-BK-RR were equipotent hypotensive agents and their effects were inhibited by icatibant (a B2R antagonist. The hypotensive effects of r-BK were potentiated by enalaprilat, but not influenced by the Arg-CPs inhibitor, which is consistent with a minor role of Arg-CPs in the metabolism of r-BK. However, in rats pretreated with both enalaprilat and Plummer’s inhibitor, the hypotensive responses and the duration of the hypotensive episode to r-BK were significantly potentiated. The hypotensive responses to r-BK-RR were not affected by enalaprilat, but were reduced by pre-treatment with the Arg

  10. A new metabotropic glutamate receptor agonist with in vivo anti-allodynic activity

    DEFF Research Database (Denmark)

    Stanley, Nathan J; Hutchinson, Mark R; Kvist, Trine

    2010-01-01

    -substituted carboxycyclopropylglycines, utilizing novel synthetic chemistry. The reaction between substituted 1,2-dioxines and an aminophosphonate furnished the cyclopropane core in a single step with all required stereochemistry of pendant groups. In vitro binding assays at metabotropic glutamate receptors revealed selective activity...

  11. The muscarinic M1/M4 receptor agonist xanomeline exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, Maibritt B; Fink-Jensen, Anders; Peacock, Linda

    2003-01-01

    Xanomeline is a muscarinic M(1)/M(4) preferring receptor agonist with little or no affinity for dopamine receptors. The compound reduces psychotic-like symptoms in patients with Alzheimer's disease and exhibits an antipsychotic-like profile in rodents without inducing extrapyramidal side effects ...

  12. Chimeric NDP-MSH and MTII melanocortin peptides with agouti-related protein (AGRP) Arg-Phe-Phe amino acids possess agonist melanocortin receptor activity.

    Science.gov (United States)

    Joseph, Christine G; Wilczynski, Andrzej; Holder, Jerry R; Xiang, Zhimin; Bauzo, Rayna M; Scott, Joseph W; Haskell-Luevano, Carrie

    2003-12-01

    Agouti-related protein (AGRP) is one of only two known endogenous antagonists of G-protein coupled receptors (GPCRs). Specifically, AGRP antagonizes the brain melanocortin-3 and -4 receptors involved in energy homeostasis, regulation of feeding behavior, and obesity. Alpha-melanocyte stimulating hormone (alpha-MSH) is one of the known endogenous agonists for these receptors. It has been hypothesized that the Arg-Phe-Phe (111-113) human AGRP amino acids may be mimicking the melanocortin agonist Phe-Arg-Trp (7-9) residue interactions with the melanocortin receptors that are important for both receptor molecular recognition and stimulation. To test this hypothesis, we generated thirteen chimeric peptide ligands based upon the melanocortin agonist peptides NDP-MSH (Ac-Ser-Tyr-Ser-Nle4-Glu-His-DPhe-Arg-Trp-Gly-Lys-Pro-Val-NH2) and MTII (Ac-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-NH2). In these chimeric ligands, the agonist DPhe-Arg-Trp amino acids were replaced by the AGRP Arg-Phe-Phe residues, and resulted in agonist activity at the mouse melanocortin receptors (mMC1R and mMC3-5Rs), supporting the hypothesis that the AGRP antagonist ligand Arg-Phe-Phe residues mimic the agonist Phe-Arg-Trp amino acids. Interestingly, the Ac-Ser-Tyr-Ser-Nle4-Glu-His-Arg-DPhe-Phe-Gly-Lys-Pro-Val-NH2 peptide possessed 7 nM mMC1R agonist potency, and is 850-fold selective for the mMC1R versus the mMC3R, 2300-fold selective for the mMC1R versus the mMC4R, and 60-fold selective for the MC1R versus the mMC5R, resulting in the discovery of a new peptide template for the design of melanocortin receptor selective ligands.

  13. Therapeutic actions of an insulin receptor activator and a novel peroxisome proliferator-activated receptor gamma agonist in the spontaneously hypertensive obese rat model of metabolic syndrome X.

    Science.gov (United States)

    Velliquette, Rodney A; Friedman, Jacob E; Shao, J; Zhang, Bei B; Ernsberger, Paul

    2005-07-01

    Insulin resistance clusters with hyperlipidemia, impaired glucose tolerance, and hypertension as metabolic syndrome X. We tested a low molecular weight insulin receptor activator, demethylasterriquinone B-1 (DMAQ-B1), and a novel indole peroxisome proliferator-activated receptor gamma agonist, 2-(2-(4-phenoxy-2-propylphenoxy)ethyl)indole-5-acetic acid (PPEIA), in spontaneously hypertensive obese rats (SHROB), a genetic model of syndrome X. Agents were given orally for 19 days. SHROB showed fasting normoglycemia but impaired glucose tolerance after an oral load, as shown by increased glucose area under the curve (AUC) [20,700 mg x min/ml versus 8100 in lean spontaneously hypertensive rats (SHR)]. Insulin resistance was indicated by 20-fold excess fasting insulin and increased insulin AUC (6300 ng x min/ml versus 990 in SHR). DMAQ-B1 did not affect glucose tolerance (glucose AUC = 21,300) but reduced fasting insulin 2-fold and insulin AUC (insulin AUC = 4300). PPEIA normalized glucose tolerance (glucose AUC = 9100) and reduced insulin AUC (to 3180) without affecting fasting insulin. PPEIA also increased food intake, fat mass, and body weight gain (81 +/- 12 versus 45 +/- 8 g in untreated controls), whereas DMAQ-B1 had no effect on body weight but reduced subscapular fat mass. PPEIA but not DMAQ-B1 reduced blood pressure. In skeletal muscle, insulin-stimulated phosphorylation of the insulin receptor and insulin receptor substrate protein 1-associated phosphatidylinositol 3-kinase activity were decreased by 40 to 55% in SHROB relative to lean SHR. PPEIA, but not DMAQ-B1, enhanced both insulin actions. SHROB also showed severe hypertriglyceridemia (355 +/- 42 mg/dl versus 65 +/- 3 in SHR) attenuated by both agents (DMAQ-B1, 228 +/- 18; PPEIA, 79 +/- 3). Both these novel antidiabetic agents attenuate insulin resistance and hypertriglyceridemia associated with metabolic syndrome but via distinct mechanisms.

  14. A conserved aspartic acid is important for agonist (VUAA1 and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco.

    Directory of Open Access Journals (Sweden)

    Brijesh N Kumar

    Full Text Available Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco. An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.

  15. Anti-kindling Effect of Bezafibrate, a Peroxisome Proliferator-activated Receptors Alpha Agonist, in Pentylenetetrazole Induced Kindling Seizure Model.

    Science.gov (United States)

    Saha, Lekha; Bhandari, Swati; Bhatia, Alka; Banerjee, Dibyajyoti; Chakrabarti, Amitava

    2014-12-01

    Studies in the animals suggested that Peroxisome proliferators activated receptors (PPARs) may be involved in seizure control and selective agonists of PPAR α or PPAR γ raise seizure thresholds. The present study was contemplated with the aim of evaluating the anti kindling effects and the mechanism of bezafibrate, a Peroxisome proliferator-activated receptors α (PPAR-α) agonist in pentylenetetrazole (PTZ) induced kindling model of seizures in rats. In a PTZ kindled Wistar rat model, different doses of bezafibrate (100 mg/kg, 200 mg/kg and 300 mg/kg) were administered intraperitoneally 30 minutes before the PTZ injection. The PTZ injection was given on alternate day till the animal became fully kindled or till 10 weeks. The parameters measured were the latency to develop kindling and incidence of kindling, histopathological study of hippocampus, hippocampal lipid peroxidation studies, serum neuron specific enolase, and hippocampal DNA fragmentation study. In this study, bezafibrate significantly reduced the incidence of kindling in PTZ treated rats and exhibited a marked prolongation in the latencies to seizures. In the present study bezafibrate decreased the thiobarbituric acid-reactive substance i.e. Malondialdehyde levels, increased the reduced glutathione levels, catalase and superoxide dismutase activity in the brain. This added to its additional neuroprotective effects. Bezafibrate also reduced the neuronal damage and apoptosis in hippocampal area of the brain. Therefore bezafibrate exerted anticonvulsant properties in PTZ induced kindling model in rats. These findings may provide insights into the understanding of the mechanism of bezafibrate as an anti kindling agent and could offer a useful support to the basic antiepileptic therapy in preventing the development of PTZ induced seizures, suggesting its potential for therapeutic applications in temporal lobe epilepsy.

  16. Peroxisome proliferator-activated receptor α agonist-induced down-regulation of hepatic glucocorticoid receptor expression in SD rats

    International Nuclear Information System (INIS)

    Chen Xiang; Li Ming; Sun Weiping; Bi Yan; Cai Mengyin; Liang Hua; Yu Qiuqiong; He Xiaoying; Weng Jianping

    2008-01-01

    It was reported that glucocorticoid production was inhibited by fenofibrate through suppression of type-1 11β-hydroxysteroid dehydrogenase gene expression in liver. The inhibition might be a negative-feedback regulation of glucocorticoid receptor (GR) activity by peroxisome proliferator-activated receptor alpha (PPARα), which is quickly induced by glucocorticoid in the liver. However, it is not clear if GR expression is changed by fenofibrate-induced PPARα activation. In this study, we tested this possibility in the liver of Sprague-Dawley rats. GR expression was reduced by fenofibrate in a time- and does-dependent manner. The inhibition was observed in liver, but not in fat and muscle. The corticosterone level in the blood was increased significantly by fenofibrate. These effects of fenofibrate were abolished by PPARα inhibitor MK886, suggesting that fenofibrate activated through PPARα. In conclusion, inhibition of GR expression may represent a new molecular mechanism for the negative feedback regulation of GR activity by PPARα

  17. Relationship between structure, conformational flexibility, and biological activity of agonists and antagonists at the N-methyl-D-aspartic acid subtype of excitatory amino acid receptors

    DEFF Research Database (Denmark)

    Madsen, U; Brehm, L; Schaumburg, Kjeld

    1990-01-01

    The relationship between conformational flexibility and agonist or antagonist actions at the N-Methyl-D-aspartic acid (NMDA) subtype of central L-glutamic acid (GLU) receptors of a series of racemic piperidinedicarboxylic acids (PDAs) was studied. The conformational analyses were based on 1H NMR...... receptors. Each of the three cyclic acidic amino acids showing NMDA agonist activities was found to exist as an equilibrium mixture of two conformers in aqueous solution. In contrast, the NMDA antagonists cis-2,3-PDA and cis-2,4-PDA as well as the inactive compounds trans-2,5-PDA and cis-2,6-PDA were shown...

  18. Direct assessment of cumulative aryl hydrocarbon receptor agonist activity in sera from experimentally exposed mice and environmentally exposed humans

    DEFF Research Database (Denmark)

    Schlezinger, Jennifer J; Bernard, Pamela L; Haas, Amelia

    2010-01-01

    (PCB)-exposed Faroe Islanders using an AhR-driven reporter cell line. To validate relationships between serum AhR agonist levels and biological outcomes, AhR agonist activity in mouse sera correlated with toxic end points. AhR agonist activity in unmanipulated ("neat") human sera was compared......, was associated with the frequency of recent pilot whale dinners, but did not correlate with levels of PCBs quantified by GC/MS. Surprisingly, significant "baseline" AhR activity was found in commercial human sera. CONCLUSIONS: An AhR reporter assay revealed cumulative levels of AhR activation potential in neat...

  19. Protease-activated receptor 2 agonist increases cell proliferation and invasion of human pancreatic cancer cells

    Science.gov (United States)

    XIE, LIQUN; DUAN, ZEXING; LIU, CAIJU; ZHENG, YANMIN; ZHOU, JING

    2015-01-01

    The aim of this study was to determine the expression of protease-activated receptor 2 (PAR-2) in the human pancreatic cancer cell line SW1990, and to evaluate its effect on cell proliferation and invasion. The expression of PAR-2 protein and mRNA in SW1990 cells was determined by immunocytochemistry and reverse transcription polymerase chain reaction (PCR), respectively. MTT and cell invasion and migration assays, as well as semi-quantitative PCR and zymography analysis, were additionally performed. PAR-2 mRNA was significantly upregulated in the cells treated with trypsin or the PAR-2 activating peptide Ser-Leu-Ile-Gly-Lys-Val (SLIGKV) (P0.05). Trypsin and SLIGKV significantly promoted SW1990 cell proliferation in a dose- and time-dependent manner (P<0.05). Compared with the control group, trypsin and SLIGKV significantly increased the mRNA expression (P<0.01) and gelatinolytic activity (P<0.01) of matrix metalloproteinase (MMP)-2. In conclusion, PAR-2 is expressed in SW1990 cells. PAR-2 activation may promote the invasion and migration of human pancreatic cancer cells by increasing MMP-2 expression. PMID:25452809

  20. Synthesis and structure-activity relationship of the first nonpeptidergic inverse agonists for the human cytomegalovirus encoded chemokine receptor US28

    NARCIS (Netherlands)

    Hulshof, Janneke W; Casarosa, Paola; Menge, Wiro M P B; Kuusisto, Leena M S; van der Goot, Henk; Smit, Martine J; de Esch, Iwan J P; Leurs, Rob

    2005-01-01

    US28 is a human cytomegalovirus (HCMV) encoded G-protein-coupled receptor that signals in a constitutively active manner. Recently, we identified 1 [5-(4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl)-2,2-diphenylpentanenitrile] as the first reported nonpeptidergic inverse agonist for a viral-encoded

  1. Peroxisome-proliferator-activated receptoragonists inhibit the release of proinflammatory cytokines from RSV-infected epithelial cells

    International Nuclear Information System (INIS)

    Arnold, Ralf; Koenig, Wolfgang

    2006-01-01

    The epithelial cells of the airways are the target cells for respiratory syncytial virus (RSV) infection and the site of the majority of the inflammation associated with the disease. Recently, peroxisome-proliferator-activated receptor γ (PPARγ), a member of the nuclear hormone receptor superfamily, has been shown to possess anti-inflammatory properties. Therefore, we investigated the role of PPARγ agonists (15d-PGJ 2 , ciglitazone and troglitazone) on the synthesis of RSV-induced cytokine release from RSV-infected human lung epithelial cells (A549). We observed that all PPARγ ligands inhibited dose-dependently the release of TNF-α, GM-CSF, IL-1α, IL-6 and the chemokines CXCL8 (IL-8) and CCL5 (RANTES) from RSV-infected A549 cells. Concomitantly, the PPARγ ligands diminished the cellular amount of mRNA encoding for IL-6, CXCL8 and CCL5 and the RSV-induced binding activity of the transcription factors NF-κB (p65/p50) and AP-1 (c-fos), respectively. Our data presented herein suggest a potential application of PPARγ ligands in the anti-inflammatory treatment of RSV infection

  2. Effects of peroxisome proliferator activated receptors (PPAR-γ and -α agonists on cochlear protection from oxidative stress.

    Directory of Open Access Journals (Sweden)

    Marijana Sekulic-Jablanovic

    Full Text Available Various insults cause ototoxicity in mammals by increasing oxidative stress leading to apoptosis of auditory hair cells (HCs. The thiazolidinediones (TZDs; e.g., pioglitazone and fibrate (e.g., fenofibrate drugs are used for the treatment of diabetes and dyslipidemia. These agents target the peroxisome proliferator-activated receptors, PPARγ and PPARα, which are transcription factors that influence glucose and lipid metabolism, inflammation, and organ protection. In this study, we explored the effects of pioglitazone and other PPAR agonists to prevent gentamicin-induced oxidative stress and apoptosis in mouse organ of Corti (OC explants. Western blots showed high levels of PPARγ and PPARα proteins in mouse OC lysates. Immunofluorescence assays indicated that PPARγ and PPARα proteins are present in auditory HCs and other cell types in the mouse cochlea. Gentamicin treatment induced production of reactive oxygen species (ROS, lipid peroxidation, caspase activation, PARP-1 cleavage, and HC apoptosis in cultured OCs. Pioglitazone mediated its anti-apoptotic effects by opposing the increase in ROS induced by gentamicin, which inhibited the subsequent formation of 4-hydroxy-2-nonenal (4-HNE and activation of pro-apoptotic mediators. Pioglitazone mediated its effects by upregulating genes that control ROS production and detoxification pathways leading to restoration of the reduced:oxidized glutathione ratio. Structurally diverse PPAR agonists were protective of HCs. Pioglitazone (PPARγ-specific, tesaglitazar (PPARγ/α-specific, and fenofibric acid (PPARα-specific all provided >90% protection from gentamicin toxicity by regulation of overlapping subsets of genes controlling ROS detoxification. This study revealed that PPARs play important roles in the cochlea, and that PPAR-targeting drugs possess therapeutic potential as treatment for hearing loss.

  3. A pepducin derived from the third intracellular loop of FPR2 is a partial agonist for direct activation of this receptor in neutrophils but a full agonist for cross-talk triggered reactivation of FPR2.

    Directory of Open Access Journals (Sweden)

    Michael Gabl

    Full Text Available We recently described a novel receptor cross-talk mechanism in neutrophils, unique in that the signals generated by the PAF receptor (PAFR and the ATP receptor (P2Y2R transfer formyl peptide receptor 1 (FPR1 from a desensitized (non-signaling state back to an actively signaling state (Forsman H et al., PLoS One, 8:e60169, 2013; Önnheim K, et al., Exp Cell Res, 323∶209, 2014. In addition to the G-protein coupled FPR1, neutrophils also express the closely related receptor FPR2. In this study we used an FPR2 specific pepducin, proposed to work as an allosteric modulator at the cytosolic signaling interface, to determine whether the cross-talk pathway is utilized also by FPR2. The pepducin used contains a fatty acid linked to a peptide sequence derived from the third intracellular loop of FPR2, and it activates as well as desensensitizes this receptor. We now show that neutrophils desensitized with the FPR2-specific pepducin display increased cellular responses to stimulation with PAF or ATP. The secondary PAF/ATP induced response was sensitive to FPR2-specific inhibitors, disclosing a receptor cross-talk mechanism underlying FPR2 reactivation. The pepducin induced an activity in naïve cells similar to that of a conventional FPR2 agonist, but with lower potency (partial efficacy, meaning that the pepducin is a partial agonist. The PAF- or ATP-induced reactivation was, however, much more pronounced when neutrophils had been desensitized to the pepducin as compared to cells desensitized to conventional agonists. The pepducin should thus in this respect be classified as a full agonist. In summary, we demonstrate that desensitized FPR2 can be transferred back to an actively signaling state by receptor cross-talk signals generated through PAFR and P2Y2R, and the difference in agonist potency with respect to pepducin-induced direct receptor activation and cross-talk reactivation of FPR2 puts the concept of functional selectivity in focus.

  4. Α-amino-β-fluorocyclopropanecarboxylic acids as a new tool for drug development: synthesis of glutamic acid analogs and agonist activity towards metabotropic glutamate receptor 4.

    Science.gov (United States)

    Lemonnier, Gérald; Lion, Cédric; Quirion, Jean-Charles; Pin, Jean-Philippe; Goudet, Cyril; Jubault, Philippe

    2012-08-01

    Herein we describe the diastereoselective synthesis of glutamic acid analogs and the evaluation of their agonist activity towards metabotropic glutamate receptor subtype 4 (mGluR4). These analogs are based on a monofluorinated cyclopropane core substituted with an α-aminoacid function. The potential of this new building block as a tool for the development of a novel class of drugs is demonstrated with racemic analog 11a that displayed the best agonist activity with an EC50 of 340 nM. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. In vitro study on the agonistic and antagonistic activities of bisphenol-S and other bisphenol-A congeners and derivatives via nuclear receptors

    International Nuclear Information System (INIS)

    Molina-Molina, José-Manuel; Amaya, Esperanza; Grimaldi, Marina; Sáenz, José-María; Real, Macarena; Fernández, Mariana F.; Balaguer, Patrick; Olea, Nicolás

    2013-01-01

    Bisphenols are a group of chemicals structurally similar to bisphenol-A (BPA) in current use as the primary raw material in the production of polycarbonate and epoxy resins. Some bisphenols are intended to replace BPA in several industrial applications. This is the case of bisphenol-S (BPS), which has an excellent stability at high temperature and resistance to sunlight. Studies on the endocrine properties of BPS have focused on its interaction with human estrogen receptor alpha (hERα), but information on its interaction with other nuclear receptors is scarce. The aim of this study was to investigate interactions of BPS, BPF, BPA and its halogenated derivatives, tetrachlorobisphenol A (TCBPA), and tetrabromobisphenol A (TBBPA), with human estrogen receptors (hERα and hERβ), androgen receptor (hAR), and pregnane X receptor (hPXR), using a panel of in vitro bioassays based on competitive binding to nuclear receptors (NRs), reporter gene expression, and cell proliferation assessment. BPS, BPF, and BPA efficiently activated both ERs, while TCBPA behaved as weak hERα agonist. Unlike BPF and BPA, BPS was more active in the hERβ versus hERα assay. BPF and BPA were full hAR antagonists (BPA > BPF), whereas BPA and BPS were weak hAR agonists. Only BPA, TCBPA, and TBBPA, were hPXR agonists (TCBPA > TBBPA > BPA). These findings provide evidence that BPA congeners and derivatives disrupt multiple NRs and may therefore interfere with the endocrine system. Hence, further research is needed to evaluate the potential endocrine-disrupting activity of putative BPA substitutes. - Highlights: • We investigated the agonist/antagonist activities of BPS, BPF, BPA, TCBPA and TBBPA. • The direct interaction of these compounds with hERα, hERβ, hAR and hPXR was studied. • BPA congeners and derivatives were found to disrupt multiple NRs. • Further evaluation of their role as endocrine-disrupting chemicals is needed

  6. In vitro study on the agonistic and antagonistic activities of bisphenol-S and other bisphenol-A congeners and derivatives via nuclear receptors

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Molina, José-Manuel, E-mail: molinajm@ugr.es [Laboratory of Medical Investigations, San Cecilio University Hospital, University of Granada, Cíber en Epidemiología y Salud Pública (CIBERESP), Granada E-18071 (Spain); Amaya, Esperanza [Laboratory of Medical Investigations, San Cecilio University Hospital, University of Granada, Cíber en Epidemiología y Salud Pública (CIBERESP), Granada E-18071 (Spain); Grimaldi, Marina [INSERM, U896, Montpellier F-34298 (France); Université de Montpellier I, Montpellier F-34298 (France); Sáenz, José-María; Real, Macarena; Fernández, Mariana F. [Laboratory of Medical Investigations, San Cecilio University Hospital, University of Granada, Cíber en Epidemiología y Salud Pública (CIBERESP), Granada E-18071 (Spain); Balaguer, Patrick [INSERM, U896, Montpellier F-34298 (France); Université de Montpellier I, Montpellier F-34298 (France); Olea, Nicolás [Laboratory of Medical Investigations, San Cecilio University Hospital, University of Granada, Cíber en Epidemiología y Salud Pública (CIBERESP), Granada E-18071 (Spain)

    2013-10-01

    Bisphenols are a group of chemicals structurally similar to bisphenol-A (BPA) in current use as the primary raw material in the production of polycarbonate and epoxy resins. Some bisphenols are intended to replace BPA in several industrial applications. This is the case of bisphenol-S (BPS), which has an excellent stability at high temperature and resistance to sunlight. Studies on the endocrine properties of BPS have focused on its interaction with human estrogen receptor alpha (hERα), but information on its interaction with other nuclear receptors is scarce. The aim of this study was to investigate interactions of BPS, BPF, BPA and its halogenated derivatives, tetrachlorobisphenol A (TCBPA), and tetrabromobisphenol A (TBBPA), with human estrogen receptors (hERα and hERβ), androgen receptor (hAR), and pregnane X receptor (hPXR), using a panel of in vitro bioassays based on competitive binding to nuclear receptors (NRs), reporter gene expression, and cell proliferation assessment. BPS, BPF, and BPA efficiently activated both ERs, while TCBPA behaved as weak hERα agonist. Unlike BPF and BPA, BPS was more active in the hERβ versus hERα assay. BPF and BPA were full hAR antagonists (BPA > BPF), whereas BPA and BPS were weak hAR agonists. Only BPA, TCBPA, and TBBPA, were hPXR agonists (TCBPA > TBBPA > BPA). These findings provide evidence that BPA congeners and derivatives disrupt multiple NRs and may therefore interfere with the endocrine system. Hence, further research is needed to evaluate the potential endocrine-disrupting activity of putative BPA substitutes. - Highlights: • We investigated the agonist/antagonist activities of BPS, BPF, BPA, TCBPA and TBBPA. • The direct interaction of these compounds with hERα, hERβ, hAR and hPXR was studied. • BPA congeners and derivatives were found to disrupt multiple NRs. • Further evaluation of their role as endocrine-disrupting chemicals is needed.

  7. Activation of Relaxin Family Receptor 1 from different mammalian species by relaxin peptide and small molecule agonist ML290

    Directory of Open Access Journals (Sweden)

    Zaohua eHuang

    2015-08-01

    Full Text Available Relaxin peptide (RLN, which signals through the relaxin family peptide 1 (RXFP1 GPCR receptor, has shown therapeutic effects in an acute heart failure clinical trial. We have identified a small molecule agonist of human RXFP1, ML290; however, it does not activate the mouse receptor. To find a suitable animal model for ML290 testing and to gain mechanistic insights into the interaction of various ligands with RXFP1, we have cloned rhesus macaque, pig, rabbit, and guinea pig RXFP1s and analyzed their activation by RLN and ML290. HEK293T cells expressing macaque or pig RXFP1 responded to relaxin and ML290 treatment as measured by an increase of cAMP production. Guinea pig RXFP1 responded to relaxin but had very low response to ML290 treatment only at highest concentrations used. The rabbit RXFP1 amino acid sequence was the most divergent, with a number of unique substitutions within the ectodomain and the 7-transmembrane domain (7TM. Two splice variants of rabbit RXFP1 derived through alternative splicing of the forth exon were identified. In contrast to the other species, rabbit RXFP1s were activated by ML290, but not with human, pig, mouse, or rabbit relaxins. Using FLAG-tagged constructs, we have shown that both rabbit RXFP1 variants are expressed on the cell surface. No binding of human Eu-labeled relaxin to rabbit RXFP1 was detected, suggesting that in this species RXFP1 might be non-functional. We used chimeric rabbit-human and guinea pig-human constructs to identify regions important for RLN or ML290 receptor activation. Chimeras with the human ectodomain and rabbit 7TM domain were activated by RLN, whereas substitution of part of the guinea pig 7TM domain with the human sequence only partially restored ML290 activation, confirming the allosteric mode of action for the two ligands. Our data demonstrate that macaque and pig models can be used for ML290 testing.

  8. Infusion of adrenergic receptor agonists and antagonists into the locus coeruleus and ventricular system of the brain. Effects on swim-motivated and spontaneous motor activity.

    Science.gov (United States)

    Weiss, J M; Simson, P G; Hoffman, L J; Ambrose, M J; Cooper, S; Webster, A

    1986-04-01

    These studies examined how pharmacological stimulation and blockade of alpha receptors would affect active motor behavior in rats. In experiment I, alpha-2 receptor antagonists (piperoxane, yohimbine) and agonists [clonidine, norepinephrine (NE)] were infused into various locations in the ventricular system of the brain, including the locus coeruleus region, and motor activity was measured. Activity was measured principally in a swim test but spontaneous (ambulatory) activity was also recorded while drugs were being infused. When infused into the locus coeruleus region, small doses of the antagonists piperoxane and yohimbine depressed activity in the swim test while infusion of the agonists clonidine and NE had the opposite effect of stimulating activity. These effects were highly specific to the region of the locus coeruleus, since infusions of these drugs into other nearby locations in the ventricular system or use of larger doses had different, often opposite effects. This was especially true of clonidine and NE which profoundly depressed activity when infused posterior to the locus coeruleus, particularly over the dorsal vagal complex. Infusion of small doses of these drugs into the lateral ventricle had effects similar to infusion into the locus coeruleus region, though less pronounced. Changes in spontaneous motor activity were also observed, but this measure differentiated the groups less well than did the swim test. In experiment II, the predominantly postsynaptic receptor agonists isoproterenol (beta agonist) and phenylephrine (alpha-1 agonist) were infused into the ventricular system. Since infusions of piperoxane and yohimbine into the locus coeruleus that decreased activity in experiment I increase the release of NE by blocking alpha-2 inhibitory receptors on cell bodies and dendrites of the locus coeruleus, experiment II tested whether ventricular infusion of predominantly postsynaptic receptor agonists would also decrease activity in the swim test

  9. Stereostructure-activity studies on agonists at the AMPA and kainate subtypes of ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Johansen, Tommy N; Greenwood, Jeremy R; Frydenvang, Karla Andrea

    2003-01-01

    (S)-Glutamic acid (Glu), the major excitatory neurotransmitter in the central nervous system, operates through ionotropic as well as metabotropic receptors and is considered to be involved in certain neurological disorders and degenerative brain diseases that are currently without any satisfactory...

  10. The muscarinic M1/M4 receptor agonist xanomeline exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, Maibritt B; Fink-Jensen, Anders; Peacock, Linda

    2003-01-01

    (EPS) at therapeutically relevant doses. In the present study, we examined whether the xanomeline-induced functional dopamine antagonism found in rodent studies could also be observed in nonhuman primates. In addition, we studied whether the lack of EPS observed in rodents also applies to primates......Xanomeline is a muscarinic M(1)/M(4) preferring receptor agonist with little or no affinity for dopamine receptors. The compound reduces psychotic-like symptoms in patients with Alzheimer's disease and exhibits an antipsychotic-like profile in rodents without inducing extrapyramidal side effects...

  11. Toll-like receptor agonist augments virus-like particle-mediated protection from Ebola virus with transient immune activation.

    Directory of Open Access Journals (Sweden)

    Karen A O Martins

    Full Text Available Identifying safe and effective adjuvants is critical for the advanced development of protein-based vaccines. Pattern recognition receptor (PRR agonists are increasingly being explored as potential adjuvants, but there is concern that the efficacy of these molecules may be dependent on potentially dangerous levels of non-specific immune activation. The filovirus virus-like particle (VLP vaccine protects mice, guinea pigs, and nonhuman primates from viral challenge. In this study, we explored the impact of a stabilized dsRNA mimic, polyICLC, on VLP vaccination of C57BL/6 mice and Hartley guinea pigs. We show that at dose levels as low as 100 ng, the adjuvant increased the efficacy of the vaccine in mice. Antigen-specific, polyfunctional CD4 and CD8 T cell responses and antibody responses increased significantly upon inclusion of adjuvant. To determine whether the efficacy of polyICLC correlated with systemic immune activation, we examined serum cytokine levels and cellular activation in the draining lymph node. PolyICLC administration was associated with increases in TNFα, IL6, MCP1, MIP1α, KC, and MIP1β levels in the periphery and with the activation of dendritic cells (DCs, NK cells, and B cells. However, this activation resolved within 24 to 72 hours at efficacious adjuvant dose levels. These studies are the first to examine the polyICLC-induced enhancement of antigen-specific immune responses in the context of non-specific immune activation, and they provide a framework from which to consider adjuvant dose levels.

  12. In silico discovery of novel Retinoic Acid Receptor agonist structures

    Directory of Open Access Journals (Sweden)

    Samuels Herbert H

    2001-06-01

    Full Text Available Abstract Background Several Retinoic Acid Receptors (RAR agonists have therapeutic activity against a variety of cancer types; however, unacceptable toxicity profiles have hindered the development of drugs. RAR agonists presenting novel structural and chemical features could therefore open new avenues for the discovery of leads against breast, lung and prostate cancer or leukemia. Results We have analysed the induced fit of the active site residues upon binding of a known ligand. The derived binding site models were used to dock over 150,000 molecules in silico (or virtually to the structure of the receptor with the Internal Coordinates Mechanics (ICM program. Thirty ligand candidates were tested in vitro. Conclusions Two novel agonists resulting from the predicted receptor model were active at 50 nM. One of them displays novel structural features which may translate into the development of new ligands for cancer therapy.

  13. Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist inhibits collagen synthesis in human hypertrophic scar fibroblasts by targeting Smad3 via miR-145

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hua-Yu; Li, Chao; Zheng, Zhao; Zhou, Qin; Guan, Hao; Su, Lin-Lin; Han, Jun-Tao; Zhu, Xiong-Xiang; Wang, Shu-yue; Li, Jun, E-mail: lijunfmmu@163.com; Hu, Da-Hai, E-mail: hudahaifmmu@aliyun.com

    2015-03-27

    The transcription factor peroxisome proliferator-activated receptor-γ (PPAR-γ) functions to regulate cell differentiation and lipid metabolism. Recently, its agonist has been documented to regulate extracellular matrix production in human dermal fibroblasts. This study explored the underlying molecular mechanisms and gene interactions in hypertrophic scar fibroblasts (HSFBs) in vitro. HSFBs were cultured and treated with or without PPAR-γ agonist or antagonist for gene expression. Bioinformatical analysis predicted that miR-145 could target Smad3 expression. Luciferase assay was used to confirm such an interaction. The data showed that PPAR-γ agonist troglitazone suppressed expression of Smad3 and Col1 in HSFBs. PPAR-γ agonist induced miR-145 at the gene transcriptional level, which in turn inhibited Smad3 expression and Col1 level in HSFBs. Furthermore, ELISA data showed that Col1 level in HSFBs was controlled by a feedback regulation mechanism involved in PPAR-γ agonist and antagonist-regulated expression of miR-145 and Smad3 in HSFBs. These findings indicate that PPAR-γ-miR-145-Smad3 axis plays a role in regulation of collagen synthesis in HSFBs. - Highlights: • PPAR-γ agonist inhibits collagen synthesis in HSFBs. • Smad3 and type I collagen expression are decreased by PPAR-γ agonist. • miR-145 expression is increased by PPAR-γ agonist in HSFBs. • Increased miR-145 inhibits collagen synthesis by targeting Smad3. • miR-145 regulates collagen synthesis.

  14. Emerging GLP-1 receptor agonists

    DEFF Research Database (Denmark)

    Lund, Asger; Knop, Filip K; Vilsbøll, Tina

    2011-01-01

    and liraglutide, as well as the emerging GLP-1R agonists including the long-acting compounds. Expert opinion: An emerging therapeutic trend toward initial or early combination therapy with metformin- and incretin-based therapy is anticipated for patients with type 2 diabetes. GLP-1-based therapy has so far proven...... development may improve the effects of GLP-1 even further with optimized pharmacokinetic profiles resulting in fewer side effects. Meta-analyses have shown promising effects on cardiovascular disease and data from ongoing multicenter trials with cardiovascular endpoints are expected in 2015....

  15. Medium chain fatty acids are selective peroxisome proliferator activated receptor (PPAR) γ activators and pan-PPAR partial agonists

    NARCIS (Netherlands)

    Liberato, Marcelo Vizoná; Nascimento, Alessandro S; Ayers, Steven D; Lin, Jean Z; Cvoro, Aleksandra; Silveira, Rodrigo L; Martínez, Leandro; Souza, Paulo C T; Saidemberg, Daniel; Deng, Tuo; Amato, Angela Angelica; Togashi, Marie; Hsueh, Willa A; Phillips, Kevin; Palma, Mário Sérgio; Neves, Francisco A R; Skaf, Munir S; Webb, Paul; Polikarpov, Igor

    2012-01-01

    Thiazolidinediones (TZDs) act through peroxisome proliferator activated receptor (PPAR) γ to increase insulin sensitivity in type 2 diabetes (T2DM), but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of

  16. Beta 2-adrenergic receptor agonists are novel regulators of macrophage activation in diabetic renal and cardiovascular complications.

    Science.gov (United States)

    Noh, Hyunjin; Yu, Mi Ra; Kim, Hyun Joo; Lee, Ji Hye; Park, Byoung-Won; Wu, I-Hsien; Matsumoto, Motonobu; King, George L

    2017-07-01

    Macrophage activation is increased in diabetes and correlated with the onset and progression of vascular complications. To identify drugs that could inhibit macrophage activation, we developed a cell-based assay and screened a 1,040 compound library for anti-inflammatory effects. Beta2-adrenergic receptor (β2AR) agonists were identified as the most potent inhibitors of phorbol myristate acetate-induced tumor necrosis factor-α production in rat bone marrow macrophages. In peripheral blood mononuclear cells isolated from streptozotocin-induced diabetic rats, β2AR agonists inhibited diabetes-induced tumor necrosis factor-α production, which was prevented by co-treatment with a selective β2AR blocker. To clarify the underlying mechanisms, THP-1 cells and bone marrow macrophages were exposed to high glucose. High glucose reduced β-arrestin2, a negative regulator of NF-κB activation, and its interaction with IκBα. This subsequently enhanced phosphorylation of IκBα and activation of NF-κB. The β2AR agonists enhanced β-arrestin2 and its interaction with IκBα, leading to downregulation of NF-κB. A siRNA specific for β-arrestin2 reversed β2AR agonist-mediated inhibition of NF-κB activation and inflammatory cytokine production. Treatment of Zucker diabetic fatty rats with a β2AR agonist for 12 weeks attenuated monocyte activation as well as pro-inflammatory and pro-fibrotic responses in the kidneys and heart. Thus, β2AR agonists might have protective effects against diabetic renal and cardiovascular complications. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  17. Principles of agonist recognition in Cys-loop receptors

    Directory of Open Access Journals (Sweden)

    Timothy eLynagh

    2014-04-01

    Full Text Available Cys-loop receptors are ligand-gated ion channels that are activated by a structurally diverse array of neurotransmitters, including acetylcholine, serotonin, glycine and GABA. After the term chemoreceptor emerged over 100 years ago, there was some wait until affinity labeling, molecular cloning, functional studies and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically diverse as glycine and serotonin has been subject to intense research over the last three decades. This review outlines the functional diversity and current structural understanding of agonist-binding sites, including those of invertebrate Cys-loop receptors. Together, this provides a framework to understand the atomic determinants involved in how these valuable therapeutic targets recognize and bind their ligands.

  18. Peroxisome proliferator-activated receptoragonists inhibit the replication of respiratory syncytial virus (RSV) in human lung epithelial cells

    International Nuclear Information System (INIS)

    Arnold, Ralf; Koenig, Wolfgang

    2006-01-01

    We have previously shown that peroxisome proliferator-activated receptor-γ (PPARγ) agonists inhibited the inflammatory response of RSV-infected human lung epithelial cells. In this study, we supply evidence that specific PPARγ agonists (15d-PGJ 2 , ciglitazone, troglitazone, Fmoc-Leu) efficiently blocked the RSV-induced cytotoxicity and development of syncytia in tissue culture (A549, HEp-2). All PPARγ agonists under study markedly inhibited the cell surface expression of the viral G and F protein on RSV-infected A549 cells. This was paralleled by a reduced cellular amount of N protein-encoding mRNA determined by real-time RT-PCR. Concomitantly, a reduced release of infectious progeny virus into the cell supernatants of human lung epithelial cells (A549, normal human bronchial epithelial cells (NHBE)) was observed. Similar results were obtained regardless whether PPARγ agonists were added prior to RSV infection or thereafter, suggesting that the agonists inhibited viral gene expression and not the primary adhesion or fusion process

  19. Peptide and small molecules rescue the functional activity and agonist potency of dysfunctional human melanocortin-4 receptor polymorphisms.

    Science.gov (United States)

    Xiang, Zhimin; Pogozheva, Irina D; Sorenson, Nicholas B; Wilczynski, Andrzej M; Holder, Jerry Ryan; Litherland, Sally A; Millard, William J; Mosberg, Henry I; Haskell-Luevano, Carrie

    2007-07-17

    The melanocortin pathway, specifically the melanocortin-4 receptor and the cognate endogenous agonist and antagonist ligands, have been strongly implicated in the regulation of energy homeostasis and satiety. Genetic studies of morbidly obese human patients and normal weight control patients have resulted in the discovery of over 70 human melanocortin-4 receptor (MC4R) polymorphisms observed as both heterozygous and homozygous forms. A number of laboratories have been studying these hMC4R polymorphisms attempting to understand the molecular mechanism(s) that might explain the obese human phenotype. Herein, we have studied 13 polymorphic hMC4Rs that have been identified to possess statistically significant decreased endogenous agonist potency with synthetic peptides and small molecules attempting to identify ligands that can pharmacologically rescue the hMC4R polymorphic agonist response. The ligands examined in this study include NDP-MSH, MTII, Ac-His-DPhe-Arg-Trp-NH2 (JRH887-9), Ac-Anc-DPhe-Arg-Trp-NH2 (amino-2-naphtylcarboxylic acid, Anc, JRH420-12), Ac-His-(pI)DPhe-Arg-Trp-NH2 (JRH322-18), chimeric AGRP-melanocortin based ligands (Tyr-c[Cys-His-DPhe-Arg-Trp-Asn-Ala-Phe-Cys]-Tyr-NH2, AMW3-130 and Ac-mini-(His-DPhe-Arg-Trp)-hAGRP-NH2, AMW3-106), and the small molecules JB25 and THIQ. The hMC4R polymorphisms included in this study are S58C, N97D, I102S, L106P, S127L, T150I, R165Q, R165W, L250Q, G252S, C271Y, Y287Stop, and I301T. These studies resulted in the NDP-MSH, MTII, AMW3-130, THIQ, and AMW3-106 ligands possessing nanomolar to subnanomolar agonist potency at the hMC4R polymorphisms examined in this study. Thus, these ligands could generically rescue the potency and stimulatory response of the abnormally functioning hMC4Rs studied and may provide tools to further clarify the molecular mechanism(s) involving these receptor modifications.

  20. Trial Watch: Toll-like receptor agonists for cancer therapy.

    Science.gov (United States)

    Vacchelli, Erika; Eggermont, Alexander; Sautès-Fridman, Catherine; Galon, Jérôme; Zitvogel, Laurence; Kroemer, Guido; Galluzzi, Lorenzo

    2013-08-01

    Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology , we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.

  1. Induction of ovulation by a potent, orally active, low molecular weight agonist (Org 43553) of the luteinizing hormone receptor.

    Science.gov (United States)

    van de Lagemaat, R; Timmers, C M; Kelder, J; van Koppen, C; Mosselman, S; Hanssen, R G J M

    2009-03-01

    In assisted reproductive technology, human chorionic gonadotrophin (hCG) is administered subcutaneously for the induction of oocyte maturation and ovulation. Our efforts to develop orally bioavailable luteinizing hormone (LH) receptor agonists have led to the discovery of Org 43553, a low molecular weight (LMW) LH receptor (LH-R) agonist. Org 43553 was tested in vitro and in vivo in pre-clinical pharmacological models to demonstrate efficacy and oral availability. Org 43553 is a potent stimulator of the human LH-R in vitro (EC(50) 3.7 nM). In primary mouse Leydig cells, Org 43553 stimulated testosterone production. Pharmacokinetic analyses showed high oral bioavailability in rats (79%) and dogs (44%) with a shorter half-life compared with hCG (3.4 versus 5.6 h in the rat). Ovulation induction by Org 43553 was demonstrated in immature mice as well as in cyclic rats after single-dose oral administration (50 mg/kg). The ovulated oocytes were of good quality as demonstrated by successful fertilization and implantation of normal embryos. In male rats, testosterone production was substantially induced after oral administration. Org 43553 is the first LMW LH-R mimetic with demonstrated in vivo efficacy upon oral administration and could therefore replace subcutaneously administered hCG. The elimination half-life of Org 43553 is substantially shorter than hCG, which could potentially represent a clinical benefit in reducing the risk of ovarian hyperstimulation syndrome (OHSS).

  2. Identification of 6-octadecynoic acid from a methanol extract of Marrubium vulgare L. as a peroxisome proliferator-activated receptor γ agonist

    Energy Technology Data Exchange (ETDEWEB)

    Ohtera, Anna; Miyamae, Yusaku; Nakai, Naomi [Graduate School of Biostudies, Kyoto University, Kyoto 606-8502 (Japan); Kawachi, Atsushi; Kawada, Kiyokazu; Han, Junkyu; Isoda, Hiroko [Alliance for Research on North Africa (ARENA), University of Tsukuba, Ibaraki 305-8572 (Japan); Faculty of Life and Environment, University of Tsukuba, Ibaraki 305-8572 (Japan); Neffati, Mohamed [Arid Zone Research Institute (IRA), Médenine 4119 (Tunisia); Akita, Toru; Maejima, Kazuhiro [Nippon Shinyaku CO., LTD., Kyoto 601-8550 (Japan); Masuda, Seiji; Kambe, Taiho [Graduate School of Biostudies, Kyoto University, Kyoto 606-8502 (Japan); Mori, Naoki; Irie, Kazuhiro [Graduate School of Agriculture, Kyoto University, Kyoto 606-8502 (Japan); Nagao, Masaya, E-mail: mnagao@kais.kyoto-u.ac.jp [Graduate School of Biostudies, Kyoto University, Kyoto 606-8502 (Japan)

    2013-10-18

    Highlights: •6-ODA, a rare fatty acid with a triple bond, was identified from Marrubium vulgare. •6-ODA was synthesized from petroselinic acid as a starting material. •6-ODA stimulated lipid accumulation in HSC-T6 and 3T3-L1 cells. •The first report of a fatty acid with a triple bond functioning as a PPARγ agonist. •This study sheds light on novel functions of a fatty acid with a triple bond. -- Abstract: 6-Octadecynoic acid (6-ODA), a fatty acid with a triple bond, was identified in the methanol extract of Marrubium vulgare L. as an agonist of peroxisome proliferator-activated receptor γ (PPARγ). Fibrogenesis caused by hepatic stellate cells is inhibited by PPARγ whose ligands are clinically used for the treatment of diabetes. Plant extracts of Marrubium vulgare L., were screened for activity to inhibit fibrosis in the hepatic stellate cell line HSC-T6 using Oil Red-O staining, which detects lipids that typically accumulate in quiescent hepatic stellate cells. A methanol extract with activity to stimulate accumulation of lipids was obtained. This extract was found to have PPARγ agonist activity using a luciferase reporter assay. After purification using several chromatographic methods, 6-ODA, a fatty acid with a triple bond, was identified as a candidate of PPARγ agonist. Synthesized 6-ODA and its derivative 9-octadecynoic acid (9-ODA), which both have a triple bond but in different positions, activated PPARγ in a luciferase reporter assay and increased lipid accumulation in 3T3-L1 adipocytes in a PPARγ-dependent manner. There is little information about the biological activity of fatty acids with a triple bond, and to our knowledge, this is the first report that 6-ODA and 9-ODA function as PPARγ agonists.

  3. Synthesis and biological evaluation of 2-heteroarylthioalkanoic acid analogues of clofibric acid as peroxisome proliferator-activated receptor alpha agonists.

    Science.gov (United States)

    Giampietro, Letizia; Ammazzalorso, Alessandra; Giancristofaro, Antonella; Lannutti, Fabio; Bettoni, Giancarlo; De Filippis, Barbara; Fantacuzzi, Marialuigia; Maccallini, Cristina; Petruzzelli, Michele; Morgano, Annalisa; Moschetta, Antonio; Amoroso, Rosa

    2009-10-22

    A series of 2-heteroarylthioalkanoic acids were synthesized through systematic structural modifications of clofibric acid and evaluated for human peroxisome proliferator-activated receptor alpha (PPARalpha) transactivation activity, with the aim of obtaining new hypolipidemic compounds. Some thiophene and benzothiazole derivatives showing a good activation of the receptor alpha were screened for activity against the PPARgamma isoform. The gene induction of selected compounds was also investigated in the human hepatoma cell line.

  4. Synthesis and structure-activity relationship of the first nonpeptidergic inverse agonists for the human cytomegalovirus encoded chemokine receptor US28.

    Science.gov (United States)

    Hulshof, Janneke W; Casarosa, Paola; Menge, Wiro M P B; Kuusisto, Leena M S; van der Goot, Henk; Smit, Martine J; de Esch, Iwan J P; Leurs, Rob

    2005-10-06

    US28 is a human cytomegalovirus (HCMV) encoded G-protein-coupled receptor that signals in a constitutively active manner. Recently, we identified 1 [5-(4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl)-2,2-diphenylpentanenitrile] as the first reported nonpeptidergic inverse agonist for a viral-encoded chemokine receptor. Interestingly, this compound is able to partially inhibit the viral entry of HIV-1. In this study we describe the synthesis of 1 and several of its analogues and unique structure-activity relationships for this first class of small-molecule ligands for the chemokine receptor US28. Moreover, the compounds have been pharmacologically characterized as inverse agonists on US28. By modification of lead structure 1, it is shown that a 4-phenylpiperidine moiety is essential for affinity and activity. Other structural features of 1 are shown to be of less importance. These compounds define the first SAR of ligands on a viral GPCR (US28) and may therefore serve as important tools to investigate the significance of US28-mediated constitutive activity during viral infection.

  5. Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10−/− mice by attenuating the activation of T cells and promoting their apoptosis

    International Nuclear Information System (INIS)

    Singh, Udai P.; Singh, Narendra P.; Singh, Balwan; Price, Robert L.; Nagarkatti, Mitzi; Nagarkatti, Prakash S.

    2012-01-01

    Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10 −/− mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10 −/− mice. After JWH-133 treatment, the percentage of CD4 + T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ► JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ► JWH-133 suppressed inflammation and toxicity to colon

  6. Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10{sup −/−} mice by attenuating the activation of T cells and promoting their apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Udai P.; Singh, Narendra P. [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Singh, Balwan [National Primate Research Center, Emory University, Atlanta GA 30329 (United States); Price, Robert L. [Department of Cell and Developmental Biology, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Mitzi [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Prakash S., E-mail: Prakash.Nagarkatti@uscmed.sc.edu [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States)

    2012-01-15

    Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10{sup −/−} mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10{sup −/−} mice. After JWH-133 treatment, the percentage of CD4{sup +} T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ► JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ► JWH-133 suppressed inflammation and

  7. Comparison of hippocampal G protein activation by 5-HT(1A) receptor agonists and the atypical antipsychotics clozapine and S16924.

    Science.gov (United States)

    Newman-Tancredi, A; Rivet, J-M; Cussac, D; Touzard, M; Chaput, C; Marini, L; Millan, M J

    2003-09-01

    This study employed [(35)S]guanosine 5'- O-(3-thiotriphosphate) ([(35)S]GTPgammaS) binding to compare the actions of antipsychotic agents known to stimulate cloned, human 5-HT(1A) receptors with those of reference agonists at postsynaptic 5-HT(1A) receptors. In rat hippocampal membranes, the following order of efficacy was observed (maximum efficacy, E(max), values relative to 5-HT=100): (+)8-OH-DPAT (85), flesinoxan (62), eltoprazine (60), S14506 (59), S16924 (48), buspirone (41), S15535 (22), clozapine (22), ziprasidone (21), pindolol (7), p-MPPI (0), WAY100,635 (0), spiperone (0). Despite differences in species and tissue source, the efficacy and potency (pEC(50)) of agonists (with the exception of clozapine) correlated well with those determined previously at human 5-HT(1A) receptors expressed in Chinese hamster ovary (CHO) cells. In contrast, clozapine was more potent at hippocampal membranes. The selective antagonists p-MPPI and WAY100,635 abolished stimulation of binding by (+)8-OH-DPAT, clozapine and S16924 (p-MPPI), indicating that these actions were mediated specifically by 5-HT(1A) receptors. Clozapine and S16924 also attenuated 5-HT- and (+)8-OH-DPAT-stimulated [(35)S]GTPgammaS binding, consistent with partial agonist properties. In [(35)S]GTPgammaS autoradiographic studies, 5-HT-induced stimulation, mediated through 5-HT(1A) receptors, was more potent in the septum (pEC(50) approximately 6.5) than in the dentate gyrus of the hippocampus (pEC(50) approximately 5) suggesting potential differences in coupling efficiency or G protein expression. Though clozapine (30 and 100 microM) did not enhance [(35)S]GTPgammaS labelling in any structure, S16924 (10 micro M) modestly increased [(35)S]GTPgammaS labelling in the dentate gyrus. On the other hand, both these antipsychotic agents attenuated 5-HT (10 microM)-stimulated [(35)S]GTPgammaS binding in the dentate gyrus and septum. In conclusion, clozapine, S16924 and ziprasidone act as partial agonists for G

  8. The adenosine A2A receptor agonist CGS 21680 exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, M B; Fuxe, K; Werge, T

    2002-01-01

    and lack of EPS in rodents could also be observed in non-human primates. We investigated the effects of CGS 21680 on behaviours induced by D-amphetamine and (-)-apomorphine in EPS-sensitized Cebus apella monkeys. CGS 21680 was administered s.c. in doses of 0.01, 0.025 and 0.05 mg/kg, alone...... and in combination with D-amphetamine and (-)-apomorphine. The monkeys were videotaped after drug administration and the tapes were rated for EPS and psychosis-like symptoms. CGS 21680 decreased apomorphine-induced behavioural unrest, arousal (0.01-0.05 mg/kg) and stereotypies (0.05 mg/kg) while amphetamine...... showed a functional anti-dopaminergic effect in Cebus apella monkeys without production of EPS. This further substantiates that adenosine A2A receptor agonists may have potential as antipsychotics with atypical profiles....

  9. The selective alpha7 nicotinic acetylcholine receptor agonist A-582941 activates immediate early genes in limbic regions of the forebrain

    DEFF Research Database (Denmark)

    Thomsen, M S; Mikkelsen, J D; Timmermann, D B

    2008-01-01

    to study whether alpha7 nAChR stimulation activates brain regions involved in cognition in juvenile as well as adult individuals. Here, we compared the effects of the novel and selective alpha7 nAChR agonist 2-methyl-5-(6-phenyl-pyridazin-3-yl)-octahydro-pyrrolo[3,4-c]pyrrole (A-582941) in the juvenile...... regions critically involved in working memory and attention. Furthermore, this effect is more pronounced in juvenile than adult rats, indicating that the juvenile forebrain is more responsive to alpha7 nAChR stimulation. This observation may be relevant in the treatment of juvenile-onset schizophrenia....

  10. An ophthalmic solution of a peroxisome proliferator-activated receptor gamma agonist prevents corneal inflammation in a rat alkali burn model.

    Science.gov (United States)

    Uchiyama, Masaaki; Shimizu, Akira; Masuda, Yukinari; Nagasaka, Shinya; Fukuda, Yuh; Takahashi, Hiroshi

    2013-01-01

    We clarified the effects of an ophthalmic solution of a peroxisome proliferator-activated receptor gamma (PPARγ) agonist on corneal inflammation and wound healing after alkali burn injury in rats. After alkali exposure, either an ophthalmic solution with 0.1% pioglitazone hydrochloride (the PPARγ group) or vehicle (the vehicle group) was topically applied to the cornea until day 14. Histological, immunohistochemical, and real-time reverse transcription polymerase chain reaction analysis were performed. After alkali injury, PPARγ expression increased, with the infiltration of many inflammatory cells. The infiltration of neutrophils and macrophages started from the corneal limbus within 6 h, and developed in the corneal center by day 7, with associated neovascularization. The accumulation of α-smooth muscle actin-positive myofibroblasts and the deposition of type III collagen were noted on day 14. The histological changes were suppressed significantly by treatment with the ophthalmic solution of the PPARγ agonist. In addition, the number of infiltrating M2 macrophages in the cornea was increased by PPARγ agonist treatment. In real-time reverse transcription polymerase chain reaction analysis, the messenger ribonucleic acid expression levels of interleukin-1β (IL-1β), IL-6, IL-8, monocyte chemoattractant protein-1, tumor necrosis factor-α, transforming growth factor beta 1, and vascular endothelial growth factor-A were decreased in the PPARγ group compared to the vehicle group in the early periods of corneal inflammation. The ophthalmic solution of the PPARγ agonist inhibited inflammation, decreased the fibrotic reaction, and prevented neovascularization in the cornea from the early phase after alkali burn injury. The ophthalmic solution of the PPARγ agonist may provide a new treatment strategy with useful clinical applications for corneal inflammation and wound healing.

  11. An ophthalmic solution of a peroxisome proliferator-activated receptor gamma agonist prevents corneal inflammation in a rat alkali burn model

    Science.gov (United States)

    Uchiyama, Masaaki; Masuda, Yukinari; Nagasaka, Shinya; Fukuda, Yuh; Takahashi, Hiroshi

    2013-01-01

    Purpose We clarified the effects of an ophthalmic solution of a peroxisome proliferator-activated receptor gamma (PPARγ) agonist on corneal inflammation and wound healing after alkali burn injury in rats. Methods After alkali exposure, either an ophthalmic solution with 0.1% pioglitazone hydrochloride (the PPARγ group) or vehicle (the vehicle group) was topically applied to the cornea until day 14. Histological, immunohistochemical, and real-time reverse transcription polymerase chain reaction analysis were performed. Results After alkali injury, PPARγ expression increased, with the infiltration of many inflammatory cells. The infiltration of neutrophils and macrophages started from the corneal limbus within 6 h, and developed in the corneal center by day 7, with associated neovascularization. The accumulation of α-smooth muscle actin-positive myofibroblasts and the deposition of type III collagen were noted on day 14. The histological changes were suppressed significantly by treatment with the ophthalmic solution of the PPARγ agonist. In addition, the number of infiltrating M2 macrophages in the cornea was increased by PPARγ agonist treatment. In real-time reverse transcription polymerase chain reaction analysis, the messenger ribonucleic acid expression levels of interleukin-1β (IL-1β), IL-6, IL-8, monocyte chemoattractant protein-1, tumor necrosis factor-α, transforming growth factor beta 1, and vascular endothelial growth factor-A were decreased in the PPARγ group compared to the vehicle group in the early periods of corneal inflammation. Conclusions The ophthalmic solution of the PPARγ agonist inhibited inflammation, decreased the fibrotic reaction, and prevented neovascularization in the cornea from the early phase after alkali burn injury. The ophthalmic solution of the PPARγ agonist may provide a new treatment strategy with useful clinical applications for corneal inflammation and wound healing. PMID:24194635

  12. AMP is an adenosine A1 receptor agonist.

    Science.gov (United States)

    Rittiner, Joseph E; Korboukh, Ilia; Hull-Ryde, Emily A; Jin, Jian; Janzen, William P; Frye, Stephen V; Zylka, Mark J

    2012-02-17

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5'-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5'-monophosphonate, ACP) directly activated the adenosine A(1) receptor (A(1)R). In contrast, AMP only activated the adenosine A(2B) receptor (A(2B)R) after hydrolysis to adenosine by ecto-5'-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A(1)R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A(1)R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A(1)R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A(1)R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine.

  13. Nicotine receptor partial agonists for smoking cessation

    Directory of Open Access Journals (Sweden)

    Kate Cahill

    Full Text Available BACKGROUND: Nicotine receptor partial agonists may help people to stop smoking by a combination of maintaining moderate levels of dopamine to counteract withdrawal symptoms (acting as an agonist and reducing smoking satisfaction (acting as an antagonist. OBJECTIVES: The primary objective of this review is to assess the efficacy and tolerability of nicotine receptor partial agonists, including cytisine, dianicline and varenicline for smoking cessation. SEARCH METHODS: We searched the Cochrane Tobacco Addiction Group's specialised register for trials, using the terms ('cytisine' or 'Tabex' or 'dianicline' or 'varenicline' or 'nicotine receptor partial agonist' in the title or abstract, or as keywords. The register is compiled from searches of MEDLINE, EMBASE, PsycINFO and Web of Science using MeSH terms and free text to identify controlled trials of interventions for smoking cessation and prevention. We contacted authors of trial reports for additional information where necessary. The latest update of the specialized register was in December 2011. We also searched online clinical trials registers. SELECTION CRITERIA: We included randomized controlled trials which compared the treatment drug with placebo. We also included comparisons with bupropion and nicotine patches where available. We excluded trials which did not report a minimum follow-up period of six months from start of treatment. DATA COLLECTION AND ANALYSIS: We extracted data on the type of participants, the dose and duration of treatment, the outcome measures, the randomization procedure, concealment of allocation, and completeness of follow-up. The main outcome measured was abstinence from smoking at longest follow-up. We used the most rigorous definition of abstinence, and preferred biochemically validated rates where they were reported. Where appropriate we pooled risk ratios (RRs, using the Mantel-Haenszel fixed-effect model. MAIN RESULTS: Two recent cytisine trials (937 people

  14. Nicotine receptor partial agonists for smoking cessation.

    Science.gov (United States)

    Cahill, Kate; Stead, Lindsay F; Lancaster, Tim

    2012-04-18

    Nicotine receptor partial agonists may help people to stop smoking by a combination of maintaining moderate levels of dopamine to counteract withdrawal symptoms (acting as an agonist) and reducing smoking satisfaction (acting as an antagonist). The primary objective of this review is to assess the efficacy and tolerability of nicotine receptor partial agonists, including cytisine, dianicline and varenicline for smoking cessation. We searched the Cochrane Tobacco Addiction Group's specialised register for trials, using the terms ('cytisine' or 'Tabex' or 'dianicline' or 'varenicline' or 'nicotine receptor partial agonist') in the title or abstract, or as keywords. The register is compiled from searches of MEDLINE, EMBASE, PsycINFO and Web of Science using MeSH terms and free text to identify controlled trials of interventions for smoking cessation and prevention. We contacted authors of trial reports for additional information where necessary. The latest update of the specialised register was in December 2011. We also searched online clinical trials registers. We included randomized controlled trials which compared the treatment drug with placebo. We also included comparisons with bupropion and nicotine patches where available. We excluded trials which did not report a minimum follow-up period of six months from start of treatment. We extracted data on the type of participants, the dose and duration of treatment, the outcome measures, the randomization procedure, concealment of allocation, and completeness of follow-up.The main outcome measured was abstinence from smoking at longest follow-up. We used the most rigorous definition of abstinence, and preferred biochemically validated rates where they were reported. Where appropriate we pooled risk ratios (RRs), using the Mantel-Haenszel fixed-effect model. Two recent cytisine trials (937 people) found that more participants taking cytisine stopped smoking compared with placebo at longest follow-up, with a pooled RR of

  15. Cannabinoid CB1 /CB2 receptor agonists attenuate hyperactivity and body weight loss in a rat model of activity-based anorexia.

    Science.gov (United States)

    Scherma, Maria; Satta, Valentina; Collu, Roberto; Boi, Maria Francesca; Usai, Paolo; Fratta, Walter; Fadda, Paola

    2017-08-01

    Anorexia nervosa (AN) is a serious psychiatric condition characterized by excessive body weight loss and disturbed perceptions of body shape and size, often associated with excessive physical activity. There is currently no effective drug-related therapy of this disease and this leads to high relapse rate. Clinical data suggest that a promising therapy to treat and reduce reoccurrence of AN may be based on the use of drugs that target the endocannabinoid (EC) system, which appears dysregulated in AN patients. The activity-based anorexia (ABA) rodent model mimics the severe body weight loss and increased physical activity, as well as the neuroendocrine disturbances (i.e. hypoleptinaemia and hypercortisolaemia) in AN. This study investigated whether cannabinoid agonists can effectively modify anorexic-like behaviours and neuroendocrine changes in rats subjected to a repeated ABA regime that mimics the human condition in which patients repeatedly undergo a recovery and illness cycle. Our data show that subchronic treatment with both the natural CB 1 /CB 2 receptor agonist Δ 9 -tetrahydrocannabinol and the synthetic CB 1 /CB 2 receptor agonist CP-55,940 significantly reduced body weight loss and running wheel activity in ABA rats. These behavioural effects were accompanied by an increase in leptin signalling and a decrease in plasma levels of corticosterone. Taken together, our results further demonstrate the involvement of the EC system in AN pathophysiology and that strategies which modulate EC signalling are useful to treat this disorder, specifically in patients where physical hyperactivity plays a central role in its progression and maintenance. © 2017 The British Pharmacological Society.

  16. Differential effects of the Toll-like receptor 2 agonists, PGN and Pam3CSK4 on anti-IgE induced human mast cell activation.

    Directory of Open Access Journals (Sweden)

    Yangyang Yu

    Full Text Available Mast cells are pivotal in the pathogenesis of allergy and inflammation. In addition to the classical IgE-dependent mechanism involving crosslinking of the high-affinity receptor for IgE (FcεRI, mast cells are also activated by Toll-like receptors (TLRs which are at the center of innate immunity. In this study, we demonstrated that the response of LAD2 cells (a human mast cell line to anti-IgE was altered in the presence of the TLR2 agonists peptidoglycan (PGN and tripalmitoyl-S-glycero-Cys-(Lys4 (Pam3CSK4. Pretreatment of PGN and Pam3CSK4 inhibited anti-IgE induced calcium mobilization and degranulation without down-regulation of FcεRI expression. Pam3CSK4 but not PGN acted in synergy with anti-IgE for IL-8 release when the TLR2 agonist was added simultaneously with anti-IgE. Studies with inhibitors of key enzymes implicated in mast cell signaling revealed that the synergistic release of IL-8 induced by Pam3CSK4 and anti-IgE involved ERK and calcineurin signaling cascades. The differential modulations of anti-IgE induced mast cell activation by PGN and Pam3CSK4 suggest that dimerization of TLR2 with TLR1 or TLR6 produced different modulating actions on FcεRI mediated human mast cell activation.

  17. Structural motifs of importance for the constitutive activity of the orphan 7TM receptor EBI2: analysis of receptor activation in the absence of an agonist

    DEFF Research Database (Denmark)

    Benned-Jensen, Tau; Rosenkilde, Mette M

    2008-01-01

    were identified by a systematic mutational analysis of 29 residues in EBI2. The cAMP response element-binding protein transcription factor was used as a measure of receptor activity and was correlated to the receptor surface expression. PheVI:13 (Phe257), and the neighboring CysVI:12 (Cys256......, but not to Lys, decreased the constitutive activity more than 7-fold compared with wt EBI2. IleIII:03 (Ile106) is located only 4 A from ArgII:20, and a favorable electrostatic interaction with ArgII:20 was created by introduction of Glu in III:03, given that the activity increased to 4.4-fold of that wt EBI2...

  18. Anticonvulsant activity of a mGlu(4alpha) receptor selective agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid.

    Science.gov (United States)

    Chapman, A G; Talebi, A; Yip, P K; Meldrum, B S

    2001-07-20

    The metabotropic Group III agonist, (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid (ACPT-1), selective for the mGlu(4alpha) receptor, suppresses sound-induced seizures in DBA/2 mice following its intracerebroventricular (i.c.v.) administration (ED(50) 5.6 [2.9-10.7], nmol i.c.v., 15 min, clonic phase) and in genetically epilepsy-prone (GEP) rats following focal administration into the inferior colliculus (ED(50) 0.08 [0.01-0.50], nmol, 60 min, clonic phase). ACPT-1 also protects against clonic seizures induced in DBA/2 mice by the Group I agonist, (RS)-3,5-dihydroxyphenylglycine (3,5-DHPG) (ED(50) 0.60 [0.29-1.2], nmol i.c.v.) and by the Group III antagonist, (RS)-alpha-methylserine-O-phosphate (MSOP) (ED(50) 49.3 [37.9-64.1], nmol i.c.v.). Another Group III agonist, (RS)-4-phosphonophenyl-glycine (PPG), preferentially activating the mGlu(8) receptor, previously shown to protect against sound-induced seizures in DBA/2 mice and GEP rats, also protects against seizures induced in DBA/2 by 3,5-DHPG (ED(50) 3.7 [2.4-5.7], nmol i.c.v.) and by the Group III antagonist, MSOP (ED(50) 40.2 [21.0-77.0], nmol i.c.v.). At very high doses (500 nmol i.c.v. and above), Group III antagonists have pro-convulsant and convulsant activity. The anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(4) receptor agonist ACPT-1, is partially reversed by the co-administration of the Group III antagonists, MSOP, (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG) or (S)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP4), in the 20-50 nmol dose range. At doses of 50-200 nmol, MPPG and MAP4 cause further reversal of the ACPT-1 anticonvulsant protection, while the MSOP effect on ACPT-1 protection is abolished at higher doses. In contrast, the anticonvulsant protection against sound-induced seizures in DBA/2 mice provided by a fully protective dose (20 nmol, i.c.v.) of the mGlu(8) receptor agonist PPG, is not

  19. Innate immune receptors in human airway smooth muscle cells: activation by TLR1/2, TLR3, TLR4, TLR7 and NOD1 agonists.

    Directory of Open Access Journals (Sweden)

    Anne Månsson Kvarnhammar

    Full Text Available BACKGROUND: Pattern-recognition receptors (PRRs, including Toll-like receptors (TLRs, NOD-like receptors (NLRs and RIG-I-like receptors (RLRs, recognize microbial components and trigger a host defense response. Respiratory tract infections are common causes of asthma exacerbations, suggesting a role for PRRs in this process. The present study aimed to examine the expression and function of PRRs on human airway smooth muscle cells (HASMCs. METHODS: Expression of TLR, NLR and RLR mRNA and proteins was determined using real-time RT-PCR, flow cytometry and immunocytochemistry. The functional responses to ligand stimulation were investigated in terms of cytokine and chemokine release, cell surface marker expression, proliferation and proteins regulating the contractile state. RESULTS: HASMCs expressed functional TLR2, TLR3, TLR4, TLR7 and NOD1. Stimulation with the corresponding agonists Pam3CSK4, poly(I:C, LPS, R-837 and iE-DAP, respectively, induced IL-6, IL-8 and GM-CSF release and up-regulation of ICAM-1 and HLA-DR, while poly(I:C also affected the release of eotaxin and RANTES. The proliferative response was slightly increased by LPS. Stimulation, most prominently with poly(I:C, down-regulated myosin light chain kinase and cysteinyl leukotriene 1 receptor expression and up-regulated β2-adrenoceptor expression. No effects were seen for agonist to TLR2/6, TLR5, TLR8, TLR9, NOD2 or RIG-I/MDA-5. CONCLUSION: Activation of TLR2, TLR3, TLR4, TLR7 and NOD1 favors a synthetic phenotype, characterized by an increased ability to release inflammatory mediators, acquire immunomodulatory properties by recruiting and interacting with other cells, and reduce the contractile state. The PRRs might therefore be of therapeutic use in the management of asthma and infection-induced disease exacerbations.

  20. Gonadotropin-releasing hormone type II (GnRH-II) agonist regulates the invasiveness of endometrial cancer cells through the GnRH-I receptor and mitogen-activated protein kinase (MAPK)-dependent activation of matrix metalloproteinase (MMP)-2

    International Nuclear Information System (INIS)

    Wu, Hsien-Ming; Wang, Hsin-Shih; Huang, Hong-Yuan; Lai, Chyong-Huey; Lee, Chyi-Long; Soong, Yung-Kuei; Leung, Peter CK

    2013-01-01

    More than 25% of patients diagnosed with endometrial carcinoma have an invasive primary cancer accompanied by metastases. Gonadotropin-releasing hormone (GnRH) plays an important role in reproduction. In mammals, expression of GnRH-II is higher than GnRH-I in reproductive tissues. Here, we examined the effect of a GnRH-II agonist on the motility of endometrial cancer cells and its mechanism of action in endometrial cancer therapy. Immunoblotting and immunohistochemistry (IHC) were used to determine the expression of the GnRH-I receptor protein in human endometrial cancer. The activity of MMP-2 in the conditioned medium was determined by gelatin zymography. Cell motility was assessed by invasion and migration assay. GnRH-I receptor si-RNA was applied to knockdown GnRH-I receptor. The GnRH-I receptor was expressed in the endometrial cancer cells. The GnRH-II agonist promoted cell motility in a dose-dependent manner. The GnRH-II agonist induced the phosphorylation of ERK1/2 and JNK, and the phosphorylation was abolished by ERK1/2 inhibitor (U0126) and the JNK inhibitor (SP600125). Cell motility promoted by GnRH-II agonist was suppressed in cells that were pretreated with U0126 and SP600125. Moreover, U0126 and SP600125 abolished the GnRH-II agonist-induced activation of MMP-2. The inhibition of MMP-2 with MMP-2 inhibitor (OA-Hy) suppressed the increase in cell motility in response to the GnRH-II agonist. Enhanced cell motility mediated by GnRH-II agonist was also suppressed by the knockdown of the endogenous GnRH-I receptor using siRNA. Our study indicates that GnRH-II agonist promoted cell motility of endometrial cancer cells through the GnRH-I receptor via the phosphorylation of ERK1/2 and JNK, and the subsequent, MAPK-dependent activation of MMP-2. Our findings represent a new concept regarding the mechanism of GnRH-II-induced cell motility in endometrial cancer cells and suggest the possibility of exploring GnRH-II as a potential therapeutic target for the

  1. Binding Mode and Structure-Activity Relationships of ITE as an Aryl Hydrocarbon Receptor (AhR) Agonist.

    Science.gov (United States)

    Dolciami, Daniela; Gargaro, Marco; Cerra, Bruno; Scalisi, Giulia; Bagnoli, Luana; Servillo, Giuseppe; Fazia, Maria Agnese Della; Puccetti, Paolo; Quintana, Francisco J; Fallarino, Francesca; Macchiarulo, Antonio

    2018-02-06

    Discovered as a modulator of the toxic response to environmental pollutants, aryl hydrocarbon receptor (AhR) has recently gained attention for its involvement in various physiological and pathological pathways. AhR is a ligand-dependent transcription factor activated by a large array of chemical compounds, which include metabolites of l-tryptophan (l-Trp) catabolism as endogenous ligands of the receptor. Among these, 2-(1'H-indole-3'-carbonyl)thiazole-4-carboxylic acid methyl ester (ITE) has attracted interest in the scientific community, being endowed with nontoxic, immunomodulatory, and anticancer AhR-mediated functions. So far, no information about the binding mode and interactions of ITE with AhR is available. In this study, we used docking and molecular dynamics to propose a putative binding mode of ITE into the ligand binding pocket of AhR. Mutagenesis studies were then instrumental in validating the proposed binding mode, identifying His 285 and Tyr 316 as important key residues for ligand-dependent receptor activation. Finally, a set of ITE analogues was synthesized and tested to further probe molecular interactions of ITE to AhR and characterize the relevance of specific functional groups in the chemical structure for receptor activity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Peroxisome Proliferator-Activated Receptor -β/δ, -γ Agonists and Resveratrol Modulate Hypoxia Induced Changes in Nuclear Receptor Activators of Muscle Oxidative Metabolism

    Directory of Open Access Journals (Sweden)

    Timothy R. H. Regnault

    2010-01-01

    Full Text Available PPAR-α, PPAR-β, and PPAR-γ, and RXR in conjunction with PGC-1α and SIRT1, activate oxidative metabolism genes determining insulin sensitivity. In utero, hypoxia is commonly observed in Intrauterine Growth Restriction (IUGR, and reduced insulin sensitivity is often observed in these infants as adults. We sought to investigate how changes in oxygen tension might directly impact muscle PPAR regulation of oxidative genes. Following eight days in culture at 1% oxygen, C2C12 muscle myoblasts displayed a reduction of PGC-1α, PPAR-α, and RXR-α mRNA, as well as CPT-1b and UCP-2 mRNA. SIRT1 and PGC-1α protein was reduced, and PPAR-γ protein increased. The addition of a PPAR-β agonist (L165,041 for the final 24 hours of 1% treatment resulted in increased levels of UCP-2 mRNA and protein whereas Rosiglitazone induced SIRT1, PGC-1α, RXR-α, PPAR-α, CPT-1b, and UCP-2 mRNA and SIRT1 protein. Under hypoxia, Resveratrol induced SIRT1, RXR-α, PPAR-α mRNA, and PPAR-γ and UCP-2 protein. These findings demonstrate that hypoxia alters the components of the PPAR pathway involved in muscle fatty acid oxidative gene transcription and translation. These results have implications for understanding selective hypoxia adaptation and how it might impact long-term muscle oxidative metabolism and insulin sensitivity.

  3. Molecular Docking, Molecular Dynamics, and Structure-Activity Relationship Explorations of 14-Oxygenated N-Methylmorphinan-6-ones as Potent μ-Opioid Receptor Agonists.

    Science.gov (United States)

    Noha, Stefan M; Schmidhammer, Helmut; Spetea, Mariana

    2017-06-21

    Among opioids, morphinans are of major importance as the most effective analgesic drugs acting primarily via μ-opioid receptor (μ-OR) activation. Our long-standing efforts in the field of opioid analgesics from the class of morphinans led to N-methylmorphinan-6-ones differently substituted at positions 5 and 14 as μ-OR agonists inducing potent analgesia and fewer undesirable effects. Herein we present the first thorough molecular modeling study and structure-activity relationship (SAR) explorations aided by docking and molecular dynamics (MD) simulations of 14-oxygenated N-methylmorphinan-6-ones to gain insights into their mode of binding to the μ-OR and interaction mechanisms. The structure of activated μ-OR provides an essential model for how ligand/μ-OR binding is encoded within small chemical differences in otherwise structurally similar morphinans. We reveal important molecular interactions that these μ-agonists share and distinguish them. The molecular docking outcomes indicate the crucial role of the relative orientation of the ligand in the μ-OR binding site, influencing the propensity of critical non-covalent interactions that are required to facilitate ligand/μ-OR interactions and receptor activation. The MD simulations point out minor differences in the tendency to form hydrogen bonds by the 4,5α-epoxy group, along with the tendency to affect the 3-7 lock switch. The emerged SARs reveal the subtle interplay between the substituents at positions 5 and 14 in the morphinan scaffold by enabling the identification of key structural elements that determine the distinct pharmacological profiles. This study provides a significant structural basis for understanding ligand binding and μ-OR activation by the 14-oxygenated N-methylmorphinan-6-ones, which should be useful for guiding drug design.

  4. Combining GLP-1 receptor agonists with insulin

    DEFF Research Database (Denmark)

    Holst, Jens Juul; Vilsbøll, T

    2013-01-01

    Due to the increasing prevalence of type 2 diabetes mellitus (T2DM), the emergent trend towards diagnosis in younger patients and the progressive nature of this disease, many more patients than before now require insulin to maintain glycaemic control. However, there is a degree of inertia among...... physicians and patients regarding the initiation and intensification of insulin therapy, in part due to concerns about the associated weight gain and increased risk of hypoglycaemia. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) increase insulin release and suppress glucagon secretion in a glucose......, compared with insulin, the antihyperglycaemic efficacy of GLP-1RAs is limited. The combination of a GLP-1RA and insulin might thus be highly effective for optimal glucose control, ameliorating the adverse effects typically associated with insulin. Data from clinical studies support the therapeutic...

  5. Identification of novel selective V2 receptor non-peptide agonists.

    Science.gov (United States)

    Del Tredici, Andria L; Vanover, Kim E; Knapp, Anne E; Bertozzi, Sine M; Nash, Norman R; Burstein, Ethan S; Lameh, Jelveh; Currier, Erika A; Davis, Robert E; Brann, Mark R; Mohell, Nina; Olsson, Roger; Piu, Fabrice

    2008-10-30

    Peptides with agonist activity at the vasopressin V(2) receptor are used clinically to treat fluid homeostasis disorders such as polyuria and central diabetes insipidus. Of these peptides, the most commonly used is desmopressin, which displays poor bioavailability as well as potent activity at the V(1b) receptor, with possible stress-related adverse effects. Thus, there is a strong need for the development of small molecule chemistries with selective V(2) receptor agonist activity. Using the functional cell-based assay Receptor Selection and Amplification Technology (R-SAT((R))), a screening effort identified three small molecule chemotypes (AC-94544, AC-88324, and AC-110484) with selective agonist activity at the V(2) receptor. One of these compounds, AC-94544, displayed over 180-fold selectivity at the V(2) receptor compared to related vasopressin and oxytocin receptors and no activity at 28 other G protein-coupled receptors (GPCRs). All three compounds also showed partial agonist activity at the V(2) receptor in a cAMP accumulation assay. In addition, in a rat model of central diabetes insipidus, AC-94544 was able to significantly reduce urine output in a dose-dependent manner. Thus, AC-94544, AC-88324, and AC-110484 represent novel opportunities for the treatment of disorders associated with V(2) receptor agonist deficiency.

  6. Agonist Binding to Chemosensory Receptors: A Systematic Bioinformatics Analysis

    Directory of Open Access Journals (Sweden)

    Fabrizio Fierro

    2017-09-01

    Full Text Available Human G-protein coupled receptors (hGPCRs constitute a large and highly pharmaceutically relevant membrane receptor superfamily. About half of the hGPCRs' family members are chemosensory receptors, involved in bitter taste and olfaction, along with a variety of other physiological processes. Hence these receptors constitute promising targets for pharmaceutical intervention. Molecular modeling has been so far the most important tool to get insights on agonist binding and receptor activation. Here we investigate both aspects by bioinformatics-based predictions across all bitter taste and odorant receptors for which site-directed mutagenesis data are available. First, we observe that state-of-the-art homology modeling combined with previously used docking procedures turned out to reproduce only a limited fraction of ligand/receptor interactions inferred by experiments. This is most probably caused by the low sequence identity with available structural templates, which limits the accuracy of the protein model and in particular of the side-chains' orientations. Methods which transcend the limited sampling of the conformational space of docking may improve the predictions. As an example corroborating this, we review here multi-scale simulations from our lab and show that, for the three complexes studied so far, they significantly enhance the predictive power of the computational approach. Second, our bioinformatics analysis provides support to previous claims that several residues, including those at positions 1.50, 2.50, and 7.52, are involved in receptor activation.

  7. AMP Is an Adenosine A1 Receptor Agonist*

    Science.gov (United States)

    Rittiner, Joseph E.; Korboukh, Ilia; Hull-Ryde, Emily A.; Jin, Jian; Janzen, William P.; Frye, Stephen V.; Zylka, Mark J.

    2012-01-01

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5′-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5′-monophosphonate, ACP) directly activated the adenosine A1 receptor (A1R). In contrast, AMP only activated the adenosine A2B receptor (A2BR) after hydrolysis to adenosine by ecto-5′-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A1R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A1R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A1R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A1R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine. PMID:22215671

  8. Identification of agonists for a group of human odorant receptors

    Directory of Open Access Journals (Sweden)

    Daniela eGonzalez-Kristeller

    2015-03-01

    Full Text Available Olfaction plays a critical role in several aspects of the human life. Odorants are detected by hundreds of odorant receptors (ORs which belong to the superfamily of G protein-coupled receptors. These receptors are expressed in the olfactory sensory neurons of the nose. The information provided by the activation of different combinations of ORs in the nose is transmitted to the brain, leading to odorant perception and emotional and behavioral responses. There are ~400 intact human ORs, and to date only a small percentage of these receptors (~10% have known agonists. The determination of the specificity of the human ORs will contribute to a better understanding of how odorants are discriminated by the olfactory system. In this work, we aimed to identify human specific ORs, that is, ORs that are present in humans but absent from other species, and their corresponding agonists. To do this, we first selected 22 OR gene sequences from the human genome with no counterparts in the mouse, rat or dog genomes. Then we used a heterologous expression system to screen a subset of these human ORs against a panel of odorants of biological relevance, including foodborne aroma volatiles. We found that different types of odorants are able to activate some of these previously uncharacterized human ORs.

  9. Transcriptional Regulation of Δ6-Desaturase by Peroxisome Proliferative-Activated Receptor δ Agonist in Human Pancreatic Cancer Cells: Role of MEK/ERK1/2 Pathway

    Directory of Open Access Journals (Sweden)

    Maryam Darabi

    2013-01-01

    Full Text Available The Δ6-desaturase (Δ6D, also known as fatty acid desaturase 2, is a regulatory enzyme in de novo fatty acid synthesis, which has been linked to obesity and diabetes. The aim of the present study was to investigate the effect of peroxisome proliferative-activated receptor δ (PPARδ agonist and MEK/ERK1/2-dependent pathway on the expression of Δ6D in human pancreatic carcinoma cell line PANC-1. PANC-1 cells cultured in RPMI-1640 were exposed to the commonly used ERK1/2 pathway inhibitor PD98059 and PPARδ agonist GW0742. Changes in mRNA and protein expression of Δ6D were then determined using real-time RT-PCR and Western blot, respectively. The expression of Δ6D (P40%, P25%, P<0.05 pretreatment. PPARδ and MEK/ERK1/2 signaling pathways affect differentially the expression of Δ6D in pancreatic cancer cells. Furthermore, there may be an inhibitory crosstalk between these two regulatory pathways on the mRNA expression of Δ6D and subsequently on Δ6D protein expression.

  10. Arctigenin functions as a selective agonist of estrogen receptor β to restrict mTORC1 activation and consequent Th17 differentiation.

    Science.gov (United States)

    Wu, Xin; Tong, Bei; Yang, Yan; Luo, Jinque; Yuan, Xusheng; Wei, Zhifeng; Yue, Mengfan; Xia, Yufeng; Dai, Yue

    2016-12-20

    Arctigenin was previously proven to inhibit Th17 cell differentiation and thereby attenuate colitis in mice by down-regulating the activation of mechanistic target of rapamycin complex 1 (mTORC1). The present study was performed to address its underlying mechanism in view of estrogen receptor (ER). The specific antagonist PHTPP or siRNA of ERβ largely diminished the inhibitory effect of arctigenin on the mTORC1 activation in T cell lines and primary CD4+ T cells under Th17-polarization condition, suggesting that arctigenin functioned in an ERβ-dependent manner. Moreover, arctigenin was recognized to be an agonist of ERβ, which could bind to ERβ with a moderate affinity, promote dissociation of ERβ/HSP90 complex and nuclear translocation and phosphorylation of ERβ, and increase the transcription activity. Following activation of ERβ, arctigenin inhibited the activity of mTORC1 by disruption of ERβ-raptor-mTOR complex assembly. Deficiency of ERβ markedly abolished arctigenin-mediated inhibition of Th17 cell differentiation. In colitis mice, the activation of ERβ, inhibition of mTORC1 activation and Th17 response by arctigenin were abolished by PHTPP treatment. In conclusion, ERβ might be the target protein of arctigenin responsible for inhibition of mTORC1 activation and resultant prevention of Th17 cell differentiation and colitis development.

  11. Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, independently of PPARγ in human glioma cells

    International Nuclear Information System (INIS)

    Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee; Koo, Hong Hoe; Sung, Ki Woong

    2012-01-01

    Highlights: ► Greater than 30 μM ciglitazone induces cell death in glioma cells. ► Cell death by ciglitazone is independent of PPARγ in glioma cells. ► CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor γ (PPARγ) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPARγ in CGZ-induced cell death was examined. At concentrations of greater than 30 μM, CGZ, a synthetic PPARγ agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 μM CGZ effectively induced cell death after pretreatment with 30 μM of the PPARγ antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPARγ was down-regulated cells by siRNA, lower concentrations of CGZ (<30 μM) were sufficient to induce cell death, although higher concentrations of CGZ (⩾30 μM) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPARγ. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPARγ in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

  12. Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, independently of PPARγ in human glioma cells.

    Science.gov (United States)

    Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee; Koo, Hong Hoe; Sung, Ki Woong

    2012-01-06

    Peroxisome proliferator-activated receptor γ (PPARγ) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPARγ in CGZ-induced cell death was examined. At concentrations of greater than 30 μM, CGZ, a synthetic PPARγ agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 μM CGZ effectively induced cell death after pretreatment with 30 μM of the PPARγ antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPARγ was down-regulated cells by siRNA, lower concentrations of CGZ (death, although higher concentrations of CGZ (≥30 μM) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPARγ. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPARγ in glioma cells, by down-regulating Akt activity and inducing MMP collapse. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reverses the adverse effects of diet-induced obesity on oocyte quality.

    Science.gov (United States)

    Minge, Cadence E; Bennett, Brenton D; Norman, Robert J; Robker, Rebecca L

    2008-05-01

    Obesity and its physiological consequences are increasingly prevalent among women of reproductive age and are associated with infertility. To investigate, female mice were fed a high-fat diet until the onset of insulin resistance, followed by assessments of ovarian gene expression, ovulation, fertilization, and oocyte developmental competence. We report defects to ovarian function associated with diet-induced obesity (DIO) that result in poor oocyte quality, subsequently reduced blastocyst survival rates, and abnormal embryonic cellular differentiation. To identify critical cellular mediators of ovarian responses to obesity induced insulin resistance, DIO females were treated for 4 d before mating with an insulin-sensitizing pharmaceutical: glucose and lipid-lowering AMP kinase activator, 5-aminoimidazole 4-carboxamide-riboside, 30 mg/kg.d; sodium salicylate, IkappaK inhibitor that reverses insulin resistance, 50 mg/kg.d; or peroxisome proliferator activated receptor-gamma agonist rosiglitazone, 10 mg/kg.d. 5-aminoimidazole 4-carboxamide-riboside or sodium salicylate treatment did not have significant effects on the reproductive parameters examined. However, embryonic development to the blastocyst stage was significantly improved when DIO mice were treated with rosiglitazone, effectively repairing development rates. Rosiglitazone also normalized DIO-associated abnormal blastomere allocation to the inner cell mass. Such improvements to oocyte quality were coupled with weight loss, improved glucose metabolism, and changes in ovarian mRNA expression of peroxisome proliferator activated receptor-regulated genes, Cd36, Scarb1, and Fabp4 cholesterol transporters. These studies demonstrate that peri-conception treatment with select insulin-sensitizing pharmaceuticals can directly influence ovarian functions and ultimately exert positive effects on oocyte developmental competence. Improved blastocyst quality in obese females treated with rosiglitazone before mating

  14. Helminthosporic acid functions as an agonist for gibberellin receptor.

    Science.gov (United States)

    Miyazaki, Sho; Jiang, Kai; Kobayashi, Masatomo; Asami, Tadao; Nakajima, Masatoshi

    2017-11-01

    Helminthosporol was isolated from a fungus, Helminthosporium sativum, as a natural plant growth regulator in 1963. It showed gibberellin-like bioactivity that stimulated the growth of the second leaf sheath of rice. After studying the structure-activity relationship between the compound and some synthesized analogs, it was found that helminthosporic acid (H-acid) has higher gibberellin-like activity and chemical stability than helminthosporol. In this study, we showed that (1) H-acid displays gibberellin-like activities not only in rice but also in Arabidopsis, (2) it regulates the expression of gibberellin-related genes, (3) it induces DELLA degradation through binding with a gibberellin receptor (GID1), and (4) it forms the GID1-(H-acid)-DELLA complex to transduce the gibberellin signal in the same manner as gibberellin. This work shows that the H-acid mode of action acts as an agonist for gibberellin receptor.

  15. Principles of agonist recognition in Cys-loop receptors

    DEFF Research Database (Denmark)

    Lynagh, Timothy Peter; Pless, Stephan Alexander

    2014-01-01

    , functional studies, and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically...

  16. Peroxisome proliferator-activated receptor α agonists modulate Th1 and Th2 chemokine secretion in normal thyrocytes and Graves' disease

    International Nuclear Information System (INIS)

    Antonelli, Alessandro; Ferrari, Silvia Martina; Frascerra, Silvia; Corrado, Alda; Pupilli, Cinzia; Bernini, Giampaolo; Benvenga, Salvatore; Ferrannini, Ele; Fallahi, Poupak

    2011-01-01

    Until now, no data are present about the effect of peroxisome proliferator-activated receptor (PPAR)α activation on the prototype Th1 [chemokine (C-X-C motif) ligand (CXCL)10] (CXCL10) and Th2 [chemokine (C-C motif) ligand 2] (CCL2) chemokines secretion in thyroid cells. The role of PPARα and PPARγ activation on CXCL10 and CCL2 secretion was tested in Graves' disease (GD) and control primary thyrocytes stimulated with interferon (IFN)γ and tumor necrosis factor (TNF)α. IFNγ stimulated both CXCL10 and CCL2 secretion in primary GD and control thyrocytes. TNFα alone stimulated CCL2 secretion, while had no effect on CXCL10. The combination of IFNγ and TNFα had a synergistic effect both on CXCL10 and CCL2 chemokines in GD thyrocytes at levels comparable to those of controls. PPARα activators inhibited the secretion of both chemokines (stimulated with IFNγ and TNFα) at a level higher (for CXCL10, about 60-72%) than PPARγ agonists (about 25-35%), which were confirmed to inhibit CXCL10, but not CCL2. Our data show that CCL2 is modulated by IFNγ and TNFα in GD and normal thyrocytes. Furthermore we first show that PPARα activators inhibit the secretion of CXCL10 and CCL2 in thyrocytes, suggesting that PPARα may be involved in the modulation of the immune response in the thyroid.

  17. ''Spare'' alpha 1-adrenergic receptors and the potency of agonists in rat vas deferens

    International Nuclear Information System (INIS)

    Minneman, K.P.; Abel, P.W.

    1984-01-01

    The existence of ''spare'' alpha 1-adrenergic receptors in rat vas deferens was examined directly using radioligand binding assays and contractility measurements. Alpha 1-adrenergic receptors in homogenates of rat vas deferens were labeled with [ 125 I]BE 2254 ( 125 IBE). Norepinephrine and other full alpha 1-adrenergic receptor agonists were much less potent in inhibiting 125 IBE binding than in contracting the vas deferens in vitro. Treatment with 300 nM phenoxybenzamine for 10 min to irreversibly inactivate alpha 1-adrenergic receptors caused a large decrease in the potency of full agonists in causing contraction of this tissue and a 23-48% decrease in the maximal contraction observed. Using those data, equilibrium constants for activation (Kact values) of the receptors by agonists were calculated. These Kact values agreed well with the equilibrium binding constants (KD values) determined from displacement of 125 IBE binding. The reduction in alpha 1-adrenergic receptor density following phenoxybenzamine treatment was determined by Scatchard analysis of specific 125 IBE binding sites and compared with the expected reduction (q values) calculated from the agonist dose-response curves before and after phenoxybenzamine treatment. This suggests that phenoxybenzamine functionally inactivates alpha 1-adrenergic receptors at or near the receptor binding site. These experiments suggest that the potencies of agonists in activating alpha 1-adrenergic receptors in rat vas deferens agree well with their potencies in binding to the receptors. The greater potency of agonists in causing contraction may be due to spare receptors in this tissue. The data also demonstrate that phenoxybenzamine irreversibly inactivates alpha 1-adrenergic receptors in rat vas deferens, but that the decrease in receptor density is much smaller than that predicted from receptor theory

  18. Pulmonary Administration of GW0742, a High-Affinity Peroxisome Proliferator-Activated Receptor Agonist, Repairs Collapsed Alveoli in an Elastase-Induced Mouse Model of Emphysema.

    Science.gov (United States)

    Ozawa, Chihiro; Horiguchi, Michiko; Akita, Tomomi; Oiso, Yuki; Abe, Kaori; Motomura, Tomoki; Yamashita, Chikamasa

    2016-01-01

    Pulmonary emphysema is a disease in which lung alveoli are irreversibly damaged, thus compromising lung function. Our previous study revealed that all-trans-retinoic acid (ATRA) induces the differentiation of human lung alveolar epithelial type 2 progenitor cells and repairs the alveoli of emphysema model mice. ATRA also reportedly has the ability to activate peroxisome proliferator-activated receptor (PPAR) β/δ. A selective PPARβ/δ ligand has been reported to induce the differentiation of human keratinocytes during wound repair. Here, we demonstrate that treatment using a high-affinity PPARβ/δ agonist, GW0742, reverses the lung tissue damage induced by elastase in emphysema-model mice and improves respiratory function. Mice treated with elastase, which collapsed their alveoli, were then treated with either 10% dimethyl sulfoxide (DMSO) in saline (control group) or GW0742 (1.0 mg/kg twice a week) by pulmonary administration. Treatment with GW0742 for 2 weeks increased the in vivo expression of surfactant proteins A and D, which are known alveolar type II epithelial cell markers. GW0742 treatment also shortened the average distance between alveolar walls in the lungs of emphysema model mice, compared with a control group treated with 10% DMSO in saline. Treatment with GW0742 for 3 weeks also improved tissue elastance (cm H2O/mL), as well as the ratio of the forced expiratory volume in the first 0.05 s to the forced vital capacity (FEV 0.05/FVC). In each of these experiments, GW0742 treatment reversed the damage caused by elastase. In conclusion, PPARβ/δ agonists are potential therapeutic agents for pulmonary emphysema.

  19. Immunomodulatory properties of mesenchymal stem cells derived from dental pulp and dental follicle are susceptible to activation by toll-like receptor agonists.

    Science.gov (United States)

    Tomic, Sergej; Djokic, Jelena; Vasilijic, Sasa; Vucevic, Dragana; Todorovic, Vera; Supic, Gordana; Colic, Miodrag

    2011-04-01

    Adult mesenchymal stem cells (MSCs) have recently become a potent tool in regenerative medicine. Due to certain shortcomings of obtaining bone marrow MSCs, alternate sources of MSCs have been sought. In this work, we studied MSCs from dental pulp (DP-MSCs) and dental follicle (DF-MSCs), isolated from the same tooth/donor, to define differences in their phenotypic properties, differentiation potential, and immunomodulatory activities. Both cell types showed colony-forming ability and expressed typical MSCs markers, but differed in the levels of their expression. DF-MSCs proliferated faster, contained cells larger in diameter, exhibited a higher potential to form adipocytes and a lower potential to form chondrocytes and osteoblasts, compared with DP-MSCs. In contrast to DF-MSCs, DP-MSCs produced the transforming growth factor (TGF)-β and suppressed proliferation of peripheral blood mononuclear cells, which could be neutralized with anti-TGF-β antibody. The treatment with toll-like receptor 3 (TLR3) agonist augmented the suppressive potential of both cell types and potentiated TGF-β and interleukin-6 secretions by these cells. TLR4 agonist augmented the suppressive potential of DF-MSCs and increased TGF-β production, but abrogated the immunosuppressive activity of DP-MSCs by inhibiting TGF-β production and the expression of indolamine-2,3-dioxygenase-1. Some of these effects correlated with the higher expression of TLR3 and TLR4 by DP-MSCs compared with DF-MSCs. When transplanted in imunocompetent xenogenic host, both cell types induced formation of granulomatous tissue. In conclusion, our results suggest that dental MSCs are functionally different and each of these functions should be further explored in vivo before their specific biomedical applications.

  20. Urolinin: The First Linear Peptidic Urotensin-II Receptor Agonist.

    Science.gov (United States)

    Bandholtz, Sebastian; Erdmann, Sarah; von Hacht, Jan Lennart; Exner, Samantha; Krause, Gerd; Kleinau, Gunnar; Grötzinger, Carsten

    2016-11-23

    This study investigated the role of individual U-II amino acid positions and side chain characteristics important for U-IIR activation. A complete permutation library of 209 U-II variants was studied in an activity screen that contained single substitution variants of each position with one of the other 19 proteinogenic amino acids. Receptor activation was measured using a cell-based high-throughput fluorescence calcium mobilization assay. We generated the first complete U-II substitution map for U-II receptor activation, resulting in a detailed view into the structural features required for receptor activation, accompanied by complementary information from receptor modeling and ligand docking studies. On the basis of the systematic SAR study of U-II, we created 33 further short and linear U-II variants from eight to three amino acids in length, including d- and other non-natural amino acids. We identified the first high-potency linear U-II analogues. Urolinin, a linear U-II agonist (nWWK-Tyr(3-NO 2 )-Abu), shows low nanomolar potency as well as improved metabolic stability.

  1. Modulation of cholinephosphotransferase activity in breast cancer cell lines by Ro5-4864, a peripheral benzodiazepine receptor agonist

    International Nuclear Information System (INIS)

    Akech, Jacqueline; Roy, Somdutta Sinha; Das, Salil K.

    2005-01-01

    Changes in phospholipid and fatty acid profile are hallmarks of cancer progression. Increase in peripheral benzodiazepine receptor expression has been implicated in breast cancer. The benzodiazepine, Ro5-4864, increases cell proliferation in some breast cancer cell lines. Biosynthesis of phosphatidylcholine (PC) has been identified as a marker for cells proliferating at high rates. Cholinephosphotransferase (CPT) is the terminal enzyme for the de novo biosynthesis of PC. We have addressed here whether Ro5-4864 facilitates some cancer causing mechanisms in breast cancer. We report that cell proliferation increases exponentially in aggressive breast cancer cell lines 11-9-1-4 and BT-549 when treated with nanomolar concentrations of Ro5-4864. This increase is seen within 24 h of treatment, consistent with the cell doubling time in these cells. Ro5-4864 also upregulates c-fos expression in breast cancer cell lines 11-9-1-4 and BT-549, while expression in non-tumorigenic cell line MCF-12A was either basal or slightly downregulated. We further examined the expression of the CPT gene in breast cancer (11-9-1-4, BT-549) and non-tumorigenic cell lines (MCF-12A, MCF-12F). We found that the CPT gene is overexpressed in breast cancer cell lines compared to the non-tumorigenic cell lines. Furthermore, the activity of CPT in forming PC is increased in the breast cancer cell lines cultured for 24 h. Additionally, we examined the CPT activity in the presence of nanomolar concentrations of Ro5-4864. Biosynthesis of PC was increased in breast cancer cell lines upon treatment. We therefore propose that Ro5-4864 facilitates PC formation, a process important in membrane biogenesis for proliferating cells

  2. Contamination with retinoic acid receptor agonists in two rivers in the Kinki region of Japan.

    Science.gov (United States)

    Inoue, Daisuke; Nakama, Koki; Sawada, Kazuko; Watanabe, Taro; Takagi, Mai; Sei, Kazunari; Yang, Min; Hirotsuji, Junji; Hu, Jianying; Nishikawa, Jun-ichi; Nakanishi, Tsuyoshi; Ike, Michihiko

    2010-04-01

    This study was conducted to investigate the agonistic activity against human retinoic acid receptor (RAR) alpha in the Lake Biwa-Yodo River and the Ina River in the Kinki region of Japan. To accomplish this, a yeast two-hybrid assay was used to elucidate the spatial and temporal variations and potential sources of RARalpha agonist contamination in the river basins. RARalpha agonistic activity was commonly detected in the surface water samples collected along two rivers at different periods, with maximum all-trans retinoic acid (atRA) equivalents of 47.6 ng-atRA/L and 23.5 ng-atRA/L being observed in Lake Biwa-Yodo River and Ina River, respectively. The results indicated that RARalpha agonists are always present and widespread in the rivers. Comparative investigation of RARalpha and estrogen receptor alpha agonistic activities at 20 stations along each river revealed that the spatial variation pattern of RARalpha agonist contamination was entirely different from that of the estrogenic compound contamination. This suggests that the effluent from municipal wastewater treatment plants, a primary source of estrogenic compounds, seemed not to be the cause of RARalpha agonist contamination in the rivers. Fractionation using high performance liquid chromatography (HPLC) directed by the bioassay found two bioactive fractions from river water samples, suggesting the presence of at least two RARalpha agonists in the rivers. Although a trial conducted to identify RARalpha agonists in the major bioactive fraction was not completed as part of this study, comparison of retention times in HPLC analysis and quantification with liquid chromatography-mass spectrometry analysis revealed that the major causative contaminants responsible for the RARalpha agonistic activity were not RAs (natural RAR ligands) and 4-oxo-RAs, while 4-oxo-RAs were identified as the major RAR agonists in sewage in Beijing, China. These findings suggest that there are unknown RARalpha agonists with high

  3. Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

    International Nuclear Information System (INIS)

    Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin; Lee, Dong-Ho; Lee, Hak Ju; Lee, Chul; Lee, Myung Koo; Hwang, Bang Yeon; Lee, Sung-Joon

    2013-01-01

    Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARα and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages

  4. Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

    Energy Technology Data Exchange (ETDEWEB)

    Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao; Lee, Ji Hae; Jun, Hee Jin [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Dong-Ho [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Lee, Hak Ju [Division of Green Business Management, Department of Forest Resources Utilization, Korean Forest Research Institute, Seoul 130-712 (Korea, Republic of); Lee, Chul; Lee, Myung Koo [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Hwang, Bang Yeon, E-mail: byhwang@chungbuk.ac.kr [College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Lee, Sung-Joon, E-mail: junelee@korea.ac.kr [Department of Biotechnology, Graduate School of Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of); Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713 (Korea, Republic of)

    2013-01-25

    Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARα and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages.

  5. MELATONIN DAN MELATONIN RECEPTOR AGONIST SEBAGAI PENANGANAN INSOMNIA PRIMER KRONIS

    Directory of Open Access Journals (Sweden)

    Ni Luh Putu Ayu Maha Iswari

    2013-04-01

    Full Text Available Melatonin is a hormone that has an important role in the mechanism of sleep. Hypnotic effects of melatonin and melatonin receptor agonist are mediated via MT1 and MT2 receptors, especially in circadian rhythm pacemaker, suprachiasmatic nucleus, which is worked on the hypothalamic sleep switch. This mechanism is quite different with the GABAergic drugs such as benzodiazepine. Agonist melatonin triggers the initiation of sleep and normalize circadian rhythms so that makes it easier to maintain sleep. The main disadvantage of melatonin in helping sleep maintenance on primary insomnia is that the half life is very short. The solution to this problem is the use of prolonged-release melatonin and melatonin receptor agonist agents such as ramelteon. Melatoninergic agonist does not cause withdrawal effects, dependence, as well as cognitive and psychomotor disorders as often happens on the use of benzodiazepine.  

  6. Scaffold-based pan-agonist design for the PPARα, PPARβ and PPARγ receptors.

    Directory of Open Access Journals (Sweden)

    Li-Song Zhang

    Full Text Available As important members of nuclear receptor superfamily, Peroxisome proliferator-activated receptors (PPAR play essential roles in regulating cellular differentiation, development, metabolism, and tumorigenesis of higher organisms. The PPAR receptors have 3 identified subtypes: PPARα, PPARβ and PPARγ, all of which have been treated as attractive targets for developing drugs to treat type 2 diabetes. Due to the undesirable side-effects, many PPAR agonists including PPARα/γ and PPARβ/γ dual agonists are stopped by US FDA in the clinical trials. An alternative strategy is to design novel pan-agonist that can simultaneously activate PPARα, PPARβ and PPARγ. Under such an idea, in the current study we adopted the core hopping algorithm and glide docking procedure to generate 7 novel compounds based on a typical PPAR pan-agonist LY465608. It was observed by the docking procedures and molecular dynamics simulations that the compounds generated by the core hopping and glide docking not only possessed the similar functions as the original LY465608 compound to activate PPARα, PPARβ and PPARγ receptors, but also had more favorable conformation for binding to the PPAR receptors. The additional absorption, distribution, metabolism and excretion (ADME predictions showed that the 7 compounds (especially Cpd#1 hold high potential to be novel lead compounds for the PPAR pan-agonist. Our findings can provide a new strategy or useful insights for designing the effective pan-agonists against the type 2 diabetes.

  7. Novel Agonist Bioisosteres and Common Structure-Activity Relationships for The Orphan G Protein-Coupled Receptor GPR139

    DEFF Research Database (Denmark)

    Shehata, Mohamed A; Jensen, Anne Cathrine Nøhr; Lissa, Delphine

    2016-01-01

    GPR139 is an orphan class A G protein-coupled receptor found mainly in the central nervous system. It has its highest expression levels in the hypothalamus and striatum, regions regulating metabolism and locomotion, respectively, and has therefore been suggested as a potential target for obesity...

  8. Binding Mode of Insulin Receptor and Agonist Peptide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Insulin is a protein hormone secreted by pancreatic β cells. One of its main functions is to keep the balance of glucose inside the body by regulating the absorption and metabolism of glucose in the periphery tissue, as well as the production and storage of hepatic glycogen. The insulin receptor is a transmembrane glycoprotein in which two α subunits with a molecular weight of 135 kD and twoβ subunits with a molecular weight of 95 kD are joined by a disulfide bond to form a β-α-α-β structure. The extracellular α subunit, especially, its three domains near the N-terminal are partially responsible for signal transduction or ligand-binding, as indicated by the experiments. The extracellular α subunits are involved in binding the ligands. The experimental results indicate that the three domains of the N-terminal of the α subunits are the main determinative parts of the insulin receptor to bind the insulin or mimetic peptide.We employed the extracellular domain (PDBID: 1IGR) of the insulin-like growth factor-1 receptor (IGF-1 R ) as the template to simulate and optimize the spatial structures of the three domains in the extracellular domain of the insulin receptor, which includes 468 residues. The work was accomplished by making use of the homology program in the Insight Ⅱ package on an Origin3800 server. The docking calculations of the insulin receptor obtained by homology with hexapeptides were carried out by means of the program Affinity. The analysis indicated that there were hydrogen bonding, and electrostatic and hydrophobic effects in the docking complex of the insulin receptor with hexapeptides.Moreover, we described the spatial orientation of a mimetic peptide with agonist activity in the docking complex. We obtained a rough model of binding of DLAPSQ or STIVYS with the insulin receptor, which provides the powerful theoretical support for designing the minimal insulin mimetic peptide with agonist activity, making it possible to develop oral small

  9. Inhibition of rotavirus ECwt infection in ICR suckling mice by N-acetylcysteine, peroxisome proliferator-activated receptor gamma agonists and cyclooxygenase-2 inhibitors

    Directory of Open Access Journals (Sweden)

    Carlos Arturo Guerrero

    2013-09-01

    Full Text Available Live attenuated vaccines have recently been introduced for preventing rotavirus disease in children. However, alternative strategies for prevention and treatment of rotavirus infection are needed mainly in developing countries where low vaccine coverage occurs. In the present work, N-acetylcysteine (NAC, ascorbic acid (AA, some nonsteroidal anti-inflammatory drugs (NSAIDs and peroxisome proliferator-activated receptor gamma (PPARγ agonists were tested for their ability to interfere with rotavirus ECwt infectivity as detected by the percentage of viral antigen-positive cells of small intestinal villi isolated from ECwt-infected ICR mice. Administration of 6 mg NAC/kg every 8 h for three days following the first diarrhoeal episode reduced viral infectivity by about 90%. Administration of AA, ibuprofen, diclofenac, pioglitazone or rosiglitazone decreased viral infectivity by about 55%, 90%, 35%, 32% and 25%, respectively. ECwt infection of mice increased expression of cyclooxygenase-2, ERp57, Hsc70, NF-κB, Hsp70, protein disulphide isomerase (PDI and PPARγ in intestinal villus cells. NAC treatment of ECwt-infected mice reduced Hsc70 and PDI expression to levels similar to those observed in villi from uninfected control mice. The present results suggest that the drugs tested in the present work could be assayed in preventing or treating rotaviral diarrhoea in children and young animals.

  10. Administration of the peroxisomal proliferator-activated receptor γ agonist pioglitazone during fractionated brain irradiation prevents radiation-induced cognitive impairment

    International Nuclear Information System (INIS)

    Zhao Weiling; Payne, Valerie; Tommasi, Ellen; Diz, Debra I.; Hsu, F.-C.; Robbins, Mike E.

    2007-01-01

    Purpose: We hypothesized that administration of the anti-inflammatory peroxisomal proliferator-activated receptor γ (PPARγ) agonist pioglitazone (Pio) to adult male rats would inhibit radiation-induced cognitive impairment. Methods and Materials: Young adult male F344 rats received one of the following: (1) fractionated whole brain irradiation (WBI); 40 or 45 Gy γ-rays in 4 or 4.5 weeks, respectively, two fractions per week and normal diet; (2) sham-irradiation and normal diet; (3) WBI plus Pio (120 ppm) before, during, and for 4 or 54 weeks postirradiation; (4) sham-irradiation plus Pio; or (5) WBI plus Pio starting 24h after completion of WBI. Results: Administration of Pio before, during, and for 4 or 54 weeks after WBI prevented Radiation-induced cognitive impairment. Administration of Pio for 54 weeks starting after completion of fractionated WBI substantially but not significantly reduced Radiation-induced cognitive impairment. Conclusions: These findings offer the promise of improving the quality of life and increasing the therapeutic window for brain tumor patients

  11. Peroxisome proliferator-activated receptor {alpha} agonists modulate Th1 and Th2 chemokine secretion in normal thyrocytes and Graves' disease

    Energy Technology Data Exchange (ETDEWEB)

    Antonelli, Alessandro, E-mail: a.antonelli@med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Ferrari, Silvia Martina, E-mail: sm.ferrari@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Frascerra, Silvia, E-mail: lafrasce@gmail.com [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Corrado, Alda, E-mail: dala_res@hotmail.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Pupilli, Cinzia, E-mail: c.pupilli@dfc.unifi.it [Endocrinology Unit, Azienda Ospedaliera Careggi and University of Florence, Viale Morgagni 85, I-50134, Florence (Italy); Bernini, Giampaolo, E-mail: g.bernini@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Benvenga, Salvatore, E-mail: s.benvenga@me.nettuno.it [Department of Clinical and Experimental Medicine, Section of Endocrinology, University of Messina, Piazza Pugliatti 1, I-98122, Messina (Italy); Ferrannini, Ele, E-mail: eferrannini@med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy); Fallahi, Poupak, E-mail: poupak@int.med.unipi.it [Department of Internal Medicine, University of Pisa-School of Medicine, Via Roma 67, I-56100, Pisa (Italy)

    2011-07-01

    Until now, no data are present about the effect of peroxisome proliferator-activated receptor (PPAR){alpha} activation on the prototype Th1 [chemokine (C-X-C motif) ligand (CXCL)10] (CXCL10) and Th2 [chemokine (C-C motif) ligand 2] (CCL2) chemokines secretion in thyroid cells. The role of PPAR{alpha} and PPAR{gamma} activation on CXCL10 and CCL2 secretion was tested in Graves' disease (GD) and control primary thyrocytes stimulated with interferon (IFN){gamma} and tumor necrosis factor (TNF){alpha}. IFN{gamma} stimulated both CXCL10 and CCL2 secretion in primary GD and control thyrocytes. TNF{alpha} alone stimulated CCL2 secretion, while had no effect on CXCL10. The combination of IFN{gamma} and TNF{alpha} had a synergistic effect both on CXCL10 and CCL2 chemokines in GD thyrocytes at levels comparable to those of controls. PPAR{alpha} activators inhibited the secretion of both chemokines (stimulated with IFN{gamma} and TNF{alpha}) at a level higher (for CXCL10, about 60-72%) than PPAR{gamma} agonists (about 25-35%), which were confirmed to inhibit CXCL10, but not CCL2. Our data show that CCL2 is modulated by IFN{gamma} and TNF{alpha} in GD and normal thyrocytes. Furthermore we first show that PPAR{alpha} activators inhibit the secretion of CXCL10 and CCL2 in thyrocytes, suggesting that PPAR{alpha} may be involved in the modulation of the immune response in the thyroid.

  12. The lipidated peptidomimetic Lau-[(S)-Aoc]-(Lys-βNphe)6-NH2 is a novel formyl peptide receptor 2 agonist that activates both human and mouse neutrophil NADPH-oxidase

    DEFF Research Database (Denmark)

    Holdfeldt, Andre; Skovbakke, Sarah Line; Winther, Malene

    2016-01-01

    Neutrophils expressing formyl peptide receptor 2 (FPR2) play key roles in host defense, immune regulation, and resolution of inflammation. Consequently, the search for FPR2-specific modulators has attracted much attention due to its therapeutic potential. Earlier described agonists......2 (F2M2), showing comparable potency in activating human and mouse neutrophils by inducing a rise in intracellular Ca2+ concentration and assembly of the superoxide-generating NADPH oxidase. This FPR2/Fpr2 agonist contains a headgroup consisting of a 2-aminooctanoic acid (Aoc) residue acylated......2 signaling as well as for development of prophylactic immunomodulatory therapy. This novel class of cross-species FPR2/Fpr2 agonists should enable translation of results obtained with mouse neutrophils (and disease models) into enhanced understanding of human inflammatory and immune diseases....

  13. Epigenetic Activity of Peroxisome Proliferator-Activated Receptor Gamma Agonists Increases the Anticancer Effect of Histone Deacetylase Inhibitors on Multiple Myeloma Cells.

    Directory of Open Access Journals (Sweden)

    Nassera Aouali

    Full Text Available Epigenetic modifications play a major role in the development of multiple myeloma. We have previously reported that the PPARγ agonist pioglitazone (PIO enhances, in-vitro, the cytotoxic effect of the Histone deacetylase inhibitor (HDACi, valproic acid (VPA, on multiple myeloma cells. Here, we described the development of a new multiple myeloma mouse model using MOLP8 cells, in order to evaluate the effect of VPA/PIO combination on the progression of myeloma cells, by analyzing the proliferation of bone marrow plasma cells. We showed that VPA/PIO delays the progression of the disease and the invasion of myeloma cells in the bone marrow. Mechanistically, we demonstrated that VPA/PIO increases the cleavage of caspase 3 and PARP, and induces the acetylation of Histone 3 (H3. Furthermore, we provided evidence that PPARγ agonist is able to enhance the action of other HDACi such as Vorinostat or Mocetinostat. Using PPARγ antagonist or siPPARγ, we strongly suggest that, as described during adipogenesis, PIO behaves as an epigenetic regulator by improving the activity of HDACi. This study highlights the therapeutic benefit of PIO/VPA combination, compared to VPA treatment as a single-arm therapy on multiple myeloma and further highlights that such combination may constitute a new promising treatment strategy which should be supported by clinical trials.

  14. Double di oxygenation by mouse 8S-lipoxygenase: Specific formation of a potent peroxisome proliferator-activated receptor α agonist

    International Nuclear Information System (INIS)

    Jisaka, Mitsuo; Iwanaga, Chitose; Takahashi, Nobuyuki; Goto, Tsuyoshi; Kawada, Teruo; Yamamoto, Tatsuyuki; Ikeda, Izumi; Nishimura, Kohji; Nagaya, Tsutomu; Fushiki, Tohru; Yokota, Kazushige

    2005-01-01

    Mouse 8S-lipoxygenase (8-LOX) metabolizes arachidonic acid (AA) specifically to 8S-hydroperoxyeicosatetraenoic acid (8S-HPETE), which will be readily reduced under physiological circumstances to 8S-hydroxyeicosatetraenoic acid (8S-HETE), a natural agonist of peroxisome proliferator-activated receptor α (PPARα). Here, we investigated whether 8-LOX could further oxygenate AA and whether the products could activate PPARs. The purified recombinant 8-LOX converted AA exclusively to 8S-HPETE and then to (8S,15S)-dihydroperoxy-5Z,9E,11Z,13E-eicosatetraenoic acid (8S,15S-diHPETE). The k cat /K m values for 8S-HPETE and AA were 3.3 x 10 3 and 2.7 x 10 4 M -1 s -1 , respectively. 8-LOX also dioxygenated 8S-HETE and 15S-H(P)ETE specifically to the corresponding 8S,15S-disubstituted derivatives. By contrast, 15-LOX-2, a human homologue of 8-LOX, produced 8S,15S-diH(P)ETE from 8S-H(P)ETE but not from AA nor 15S-H(P)ETE. 8S,15S-diHETE activated PPARα more strongly than 8S-HETE did. The present results suggest that 8S,15S-diH(P)ETE as well as 8S-H(P)ETE would contribute to the physiological function of 8-LOX and also that 8-LOX can function as a potential 15-LOX

  15. Abnormalities in Dynamic Brain Activity Caused by Mild Traumatic Brain Injury Are Partially Rescued by the Cannabinoid Type-2 Receptor Inverse Agonist SMM-189.

    Science.gov (United States)

    Liu, Yu; McAfee, Samuel S; Guley, Natalie M; Del Mar, Nobel; Bu, Wei; Heldt, Scott A; Honig, Marcia G; Moore, Bob M; Reiner, Anton; Heck, Detlef H

    2017-01-01

    Mild traumatic brain injury (mTBI) can cause severe long-term cognitive and emotional deficits, including impaired memory, depression, and persevering fear, but the neuropathological basis of these deficits is uncertain. As medial prefrontal cortex (mPFC) and hippocampus play important roles in memory and emotion, we used multi-site, multi-electrode recordings of oscillatory neuronal activity in local field potentials (LFPs) in awake, head-fixed mice to determine if the functioning of these regions was abnormal after mTBI, using a closed-skull focal cranial blast model. We evaluated mPFC, hippocampus CA1, and primary somatosensory/visual cortical areas (S1/V1). Although mTBI did not alter the power of oscillations, it did cause increased coherence of θ (4-10 Hz) and β (10-30 Hz) oscillations within mPFC and S1/V1, reduced CA1 sharp-wave ripple (SWR)-evoked LFP activity in mPFC, downshifted SWR frequencies in CA1, and enhanced θ-γ phase-amplitude coupling (PAC) within mPFC. These abnormalities might be linked to the impaired memory, depression, and persevering fear seen after mTBI. Treatment with the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189 has been shown to mitigate functional deficits and neuronal injury after mTBI in mice. We found that SMM-189 also reversed most of the observed neurophysiological abnormalities. This neurophysiological rescue is likely to stem from the previously reported reduction in neuron loss and/or the preservation of neuronal function and connectivity resulting from SMM-189 treatment, which appears to stem from the biasing of microglia from the proinflammatory M1 state to the prohealing M2 state by SMM-189.

  16. [Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

    Science.gov (United States)

    Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

  17. Novel kinin B1 receptor agonists with improved pharmacological profiles.

    Science.gov (United States)

    Côté, Jérôme; Savard, Martin; Bovenzi, Veronica; Bélanger, Simon; Morin, Josée; Neugebauer, Witold; Larouche, Annie; Dubuc, Céléna; Gobeil, Fernand

    2009-04-01

    There is some evidence to suggest that inducible kinin B1 receptors (B1R) may play beneficial and protecting roles in cardiovascular-related pathologies such as hypertension, diabetes, and ischemic organ diseases. Peptide B1R agonists bearing optimized pharmacological features (high potency, selectivity and stability toward proteolysis) hold promise as valuable therapeutic agents in the treatment of these diseases. In the present study, we used solid-phase methodology to synthesize a series of novel peptide analogues based on the sequence of Sar[dPhe(8)]desArg(9)-bradykinin, a relatively stable peptide agonist with moderate affinity for the human B1R. We evaluated the pharmacological properties of these peptides using (1) in vitro competitive binding experiments on recombinant human B1R and B2R (for index of selectivity determination) in transiently transfected human embryonic kidney 293 cells (HEK-293T cells), (2) ex vivo vasomotor assays on isolated human umbilical veins expressing endogenous human B1R, and (3) in vivo blood pressure tests using anesthetized lipopolysaccharide-immunostimulated rabbits. Key chemical modifications at the N-terminus, the positions 3 and 5 on Sar[dPhe(8)]desArg(9)-bradykinin led to potent analogues. For example, peptides 18 (SarLys[Hyp(3),Cha(5), dPhe(8)]desArg(9)-bradykinin) and 20 (SarLys[Hyp(3),Igl(5), dPhe(8)]desArg(9)-bradykinin) outperformed the parental molecule in terms of affinity, functional potency and duration of action in vitro and in vivo. These selective agonists should be valuable in future animal and human studies to investigate the potential benefits of B1R activation.

  18. Melanocortin tetrapeptide Ac-His-DPhe-Arg-Trp-NH2 modified at the para position of the benzyl side chain (DPhe): importance for mouse melanocortin-3 receptor agonist versus antagonist activity.

    Science.gov (United States)

    Proneth, Bettina; Pogozheva, Irina D; Portillo, Federico P; Mosberg, Henry I; Haskell-Luevano, Carrie

    2008-09-25

    The melanocortin-3 and -4 receptors (MC3R, MC4R) have been implicated in energy homeostasis and obesity. Whereas the physiological role of the MC4R is extensively studied, little is known about the MC3R. One caveat is the limited availability of ligands that are selective for the MC3R. Previous studies identified Ac-His-DPhe(p-I)-Arg-Trp-NH 2, which possessed partial agonist/antagonist pharmacology at the mMC3R while retaining full nanomolar agonist pharmacology at the mMC4R. These data allowed for the hypothesis that the DPhe position in melanocortin tetrapeptides can be used to examine ligand side-chain determinants important for differentiation of mMC3R agonist versus antagonist activity. A series of 15 DPhe (7) modified Ac-His-DPhe (7)-Arg-Trp-NH 2 tetrapeptides has been synthesized and pharmacologically characterized. Most notable results include the identification of modifications that resulted in potent antagonists/partial agonists at the mMC3R and full, potent agonists at the mMC4R. These SAR studies provide experimental evidence that the molecular mechanism of antagonism at the mMC3R differentiates this subtype from the mMC4R.

  19. Misoprostol, an anti-ulcer agent and PGE2 receptor agonist, protects against cerebral ischemia

    OpenAIRE

    Li, Jun; Liang, Xibin; Wang, Qian; Breyer, Richard M.; McCullough, Louise; Andreasson, Katrin

    2008-01-01

    Induction of COX-2 activity in cerebral ischemia results in increased neuronal injury and infarct size. Recent studies investigating neurotoxic mechanisms of COX-2 demonstrate both toxic and paradoxically protective effects of downstream prostaglandin receptor signaling pathways. We tested whether misoprostol, a PGE2 receptor agonist that is utilized clinically as an anti-ulcer agent and signals through the protective PGE2 EP2, EP3, and EP4 receptors, would reduce brain injury in the murine m...

  20. Unique interaction pattern for a functionally biased ghrelin receptor agonist

    DEFF Research Database (Denmark)

    Sivertsen, Bjørn Behrens; Lang, Manja; Frimurer, Thomas M.

    2011-01-01

    Based on the conformationally constrained D-Trp-Phe-D-Trp (wFw) core of the prototype inverse agonist [D-Arg(1),D-Phe(5),D-Trp(7,9),Leu(11)]substance P, a series of novel, small, peptide-mimetic agonists for the ghrelin receptor were generated. By using various simple, ring-constrained spacers...... connecting the D-Trp-Phe-D-Trp motif with the important C-terminal carboxyamide group, 40 nm agonism potency was obtained and also in one case (wFw-Isn-NH(2), where Isn is isonipecotic acid) ~80% efficacy. However, in contrast to all previously reported ghrelin receptor agonists, the piperidine-constrained w......Fw-Isn-NH(2) was found to be a functionally biased agonist. Thus, wFw-Isn-NH(2) mediated potent and efficacious signaling through the Ga(q) and ERK1/2 signaling pathways, but in contrast to all previous ghrelin receptor agonists it did not signal through the serum response element, conceivably the Ga(12...

  1. Rosiglitazone, a Peroxisome Proliferator-Activated Receptor (PPAR)-γ Agonist, Attenuates Inflammation Via NF-κB Inhibition in Lipopolysaccharide-Induced Peritonitis.

    Science.gov (United States)

    Zhang, Yun-Fang; Zou, Xun-Liang; Wu, Jun; Yu, Xue-Qing; Yang, Xiao

    2015-12-01

    We assessed the anti-inflammatory effect of peroxisome proliferator-activated receptor (PPAR)-γ agonist, rosiglitazone, in a lipopolysaccharide (LPS)-induced peritonitis rat model. LPS was intraperitoneally injected into rats to establish peritonitis model. Male Sprague-Dawley (SD) rats were assigned to normal saline (the solvent of LPS), LPS, rosiglitazone plus LPS, and rosiglitazone alone. A simple peritoneal equilibrium test was performed with 20 ml 4.25 % peritoneal dialysis fluid. We measured the leukocyte count in dialysate and ultrafiltration volume. Peritoneal membrane histochemical staining was performed, and peritoneal thickness was assessed. CD40 and intercellular adhesion molecule-1 messenger RNA (ICAM-1 mRNA) levels in rat visceral peritoneum were detected by reverse transcription (RT)-PCR. IL-6 in rat peritoneal dialysis effluent was measured using enzyme-linked immunosorbent assay. The phosphorylation of NF-κB-p65 and IκBα was analyzed by Western blot. LPS administration resulted in increased peritoneal thickness and decreased ultrafiltration volume. Rosiglitazone pretreatment significantly decreased peritoneal thickness. In addition to CD40 and ICAM-1 mRNA expression, the IL-6, p-p65, and p-IκBα protein expressions were enhanced in LPS-administered animals. Rosiglitazone pretreatment significantly decreased ICAM-1 mRNA upregulation, secretion of IL-6 protein, and phosphorylation of NF-κB-p65 and IκBα without decreasing CD40 mRNA expression. Rosiglitazone has a protective effect in peritonitis, simultaneously decreasing NF-κB phosphorylation, suggesting that NF-κB signaling pathway mediated peritoneal inflammation induced by LPS. PPAR-γ might be considered a potential therapeutic target against peritonitis.

  2. Design and synthesis of small molecule agonists of EphA2 receptor.

    Science.gov (United States)

    Petty, Aaron; Idippily, Nethrie; Bobba, Viharika; Geldenhuys, Werner J; Zhong, Bo; Su, Bin; Wang, Bingcheng

    2018-01-01

    Ligand-independent activation of EphA2 receptor kinase promotes cancer metastasis and invasion. Activating EphA2 receptor tyrosine kinase with small molecule agonist is a novel strategy to treat EphA2 overexpressing cancer. In this study, we performed a lead optimization of a small molecule Doxazosin that was identified as an EphA2 receptor agonist. 33 new analogs were developed and evaluated; a structure-activity relationship was summarized based on the EphA2 activation of these derivatives. Two new derivative compounds 24 and 27 showed much improved activity compared to Doxazosin. Compound 24 possesses a bulky amide moiety, and compound 27 has a dimeric structure that is very different to the parental compound. Compound 27 with a twelve-carbon linker of the dimer activated the kinase and induced receptor internalization and cell death with the best potency. Another dimer with a six-carbon linker has significantly reduced potency compared to the dimer with a longer linker, suggesting that the length of the linker is critical for the activity of the dimeric agonist. To explore the receptor binding characteristics of the new molecules, we applied a docking study to examine how the small molecule binds to the EphA2 receptor. The results reveal that compounds 24 and 27 form more hydrogen bonds to EphA2 than Doxazosin, suggesting that they may have higher binding affinity to the receptor. Published by Elsevier Masson SAS.

  3. Discovery of novel acetanilide derivatives as potent and selective beta3-adrenergic receptor agonists.

    Science.gov (United States)

    Maruyama, Tatsuya; Onda, Kenichi; Hayakawa, Masahiko; Matsui, Tetsuo; Takasu, Toshiyuki; Ohta, Mitsuaki

    2009-06-01

    In the search for potent and selective human beta3-adrenergic receptor (AR) agonists as potential drugs for the treatment of obesity and noninsulin-dependent (type II) diabetes, a novel series of acetanilide-based analogues were prepared and their biological activities were evaluated at the human beta3-, beta2-, and beta1-ARs. Among these compounds, 2-pyridylacetanilide (2f), pyrimidin-2-ylacetanilide (2u), and pyrazin-2-ylacetanilide (2v) derivatives exhibited potent agonistic activity at the beta3-AR with functional selectivity over the beta1- and beta2-ARs. In particular, compound 2u was found to be the most potent and selective beta3-AR agonist with an EC(50) value of 0.11 microM and no agonistic activity for either the beta1- or beta2-AR. In addition, 2f, 2u, and 2v showed significant hypoglycemic activity in a rodent diabetic model.

  4. Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay.

    Directory of Open Access Journals (Sweden)

    Yiyi Sun

    Full Text Available Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (--arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases.

  5. Thrombopoietin-receptor agonists in haematological disorders: The Danish experience

    DEFF Research Database (Denmark)

    Gudbrandsdottir, Sif; Frederiksen, Henrik; Hasselbalch, Hans

    2011-01-01

    The objective of this study was to investigate the use of thrombopoietin-receptor agonists (TPO-ra) in patients with refractory primary immune thrombocytopenia (ITP) as well as off-label use of TPO-ra in Danish haematology departments. Hospital medical records from 32 of the 39 patients having re...

  6. Differential modulation of Beta-adrenergic receptor signaling by trace amine-associated receptor 1 agonists.

    Directory of Open Access Journals (Sweden)

    Gunnar Kleinau

    Full Text Available Trace amine-associated receptors (TAAR are rhodopsin-like G-protein-coupled receptors (GPCR. TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR, phenylethylamine (PEA, octopamine (OA, but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1 and 2 (ADRB2 have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR octopamine (OAR, ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes.

  7. Agonist discrimination between AMPA receptor subtypes

    DEFF Research Database (Denmark)

    Coquelle, T; Christensen, J K; Banke, T G

    2000-01-01

    The lack of subtype-selective compounds for AMPA receptors (AMPA-R) led us to search for compounds with such selectivity. Homoibotenic acid analogues were investigated at recombinant GluR1o, GluR2o(R), GluR3o and GluR1o + 3o receptors expressed in Sf9 insect cells and affinities determined in [3H...

  8. Assembly of high-affinity insulin receptor agonists and antagonists from peptide building blocks

    Science.gov (United States)

    Schäffer, Lauge; Brissette, Renee E.; Spetzler, Jane C.; Pillutla, Renuka C.; Østergaard, Søren; Lennick, Michael; Brandt, Jakob; Fletcher, Paul W.; Danielsen, Gillian M.; Hsiao, Ku-Chuan; Andersen, Asser S.; Dedova, Olga; Ribel, Ulla; Hoeg-Jensen, Thomas; Hansen, Per Hertz; Blume, Arthur J.; Markussen, Jan; Goldstein, Neil I.

    2003-01-01

    Insulin is thought to elicit its effects by crosslinking the two extracellular α-subunits of its receptor, thereby inducing a conformational change in the receptor, which activates the intracellular tyrosine kinase signaling cascade. Previously we identified a series of peptides binding to two discrete hotspots on the insulin receptor. Here we show that covalent linkage of such peptides into homodimers or heterodimers results in insulin agonists or antagonists, depending on how the peptides are linked. An optimized agonist has been shown, both in vitro and in vivo, to have a potency close to that of insulin itself. The ability to construct such peptide derivatives may offer a path for developing agonists or antagonists for treatment of a wide variety of diseases. PMID:12684539

  9. Inverse agonist and neutral antagonist actions of synthetic compounds at an insect 5-HT1 receptor.

    Science.gov (United States)

    Troppmann, B; Balfanz, S; Baumann, A; Blenau, W

    2010-04-01

    5-Hydroxytryptamine (5-HT) has been shown to control and modulate many physiological and behavioural functions in insects. In this study, we report the cloning and pharmacological properties of a 5-HT(1) receptor of an insect model for neurobiology, physiology and pharmacology. A cDNA encoding for the Periplaneta americana 5-HT(1) receptor was amplified from brain cDNA. The receptor was stably expressed in HEK 293 cells, and the functional and pharmacological properties were determined in cAMP assays. Receptor distribution was investigated by RT-PCR and by immunocytochemistry using an affinity-purified polyclonal antiserum. The P. americana 5-HT(1) receptor (Pea5-HT(1)) shares pronounced sequence and functional similarity with mammalian 5-HT(1) receptors. Activation with 5-HT reduced adenylyl cyclase activity in a dose-dependent manner. Pea5-HT(1) was expressed as a constitutively active receptor with methiothepin acting as a neutral antagonist, and WAY 100635 as an inverse agonist. Receptor mRNA was present in various tissues including brain, salivary glands and midgut. Receptor-specific antibodies showed that the native protein was expressed in a glycosylated form in membrane samples of brain and salivary glands. This study marks the first pharmacological identification of an inverse agonist and a neutral antagonist at an insect 5-HT(1) receptor. The results presented here should facilitate further analyses of 5-HT(1) receptors in mediating central and peripheral effects of 5-HT in insects.

  10. β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo

    Science.gov (United States)

    Jiang, Youde; Zhang, Qiuhua; Ye, Eun-Ah

    2014-01-01

    Purpose Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. Methods Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1Ser307, and IRTyr960. Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. Results A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. Conclusions Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance–based retinal cell apoptosis. PMID:24966659

  11. GABAA receptor partial agonists and antagonists

    DEFF Research Database (Denmark)

    Krall, Jacob; Balle, Thomas; Krogsgaard-Larsen, Niels

    2015-01-01

    to the local temporal pattern of GABA impact, enabling phasic or tonic inhibition. Specific GABAAR antagonists are essential tools for physiological and pharmacological elucidation of the different type of GABAAR inhibition. However, distinct selectivity among the receptor subtypes (populations) has been shown...... antagonists have been essential in defining the tonic current but both remaining issues concerning the GABAARs involved and the therapeutic possibilities of modulating tonic inhibition underline the need for GABAAR antagonists with improved selectivity....

  12. Synergistic action of octopamine receptor agonists on the activity of selected novel insecticides for control of dengue vector Aedes aegypti (Diptera: Culicidae) mosquito.

    Science.gov (United States)

    Ahmed, Mohamed Ahmed Ibrahim; Vogel, Christoph Franz Adam

    2015-05-01

    Studying insecticide resistance in mosquitoes has attracted the attention of many scientists to elucidate the pathways of resistance development and to design novel strategies in order to prevent or minimize the spread and evolution of resistance. Here, we tested the synergistic action of piperonyl butoxide (PBO) and two octopamine receptor (OR) agonists, amitraz (AMZ) and chlordimeform (CDM) on selected novel insecticides to increase their lethal action on the fourth instar larvae of Aedes aegypti L. However, chlorfenapyr was the most toxic insecticide (LC50 = 193, 102, and 48 ng/ml, after 24, 48, and 72 h exposure, respectively) tested. Further, PBO synergized all insecticides and the most toxic combinatorial insecticide was nitenpyram even after 48 and 72 h exposure. In addition, OR agonists significantly synergized most of the selected insecticides especially after 48 and 72 h exposure. The results imply that the synergistic effects of amitraz are a promising approach in increasing the potency of certain insecticides in controlling the dengue vector Ae. aegypti mosquito. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. A Pepducin Derived from the Third Intracellular Loop of FPR2 Is a Partial Agonist for Direct Activation of This Receptor in Neutrophils But a Full Agonist for Cross-Talk Triggered Reactivation of FPR2

    DEFF Research Database (Denmark)

    Gabl, Michael; Winther, Malene; Skovbakke, Sarah Line

    2014-01-01

    We recently described a novel receptor cross-talk mechanism in neutrophils, unique in that the signals generated by the PAF receptor (PAFR) and the ATP receptor (P2Y2R) transfer formyl peptide receptor 1 (FPR1) from a desensitized (non-signaling) state back to an actively signaling state (Forsman H...... et al., PLoS One, 8:e60169, 2013; Önnheim K, et al., Exp Cell Res, 323:209, 2014). In addition to the G-protein coupled FPR1, neutrophils also express the closely related receptor FPR2. In this study we used an FPR2 specific pepducin, proposed to work as an allosteric modulator at the cytosolic...... signaling interface, to determine whether the cross-talk pathway is utilized also by FPR2. The pepducin used contains a fatty acid linked to a peptide sequence derived from the third intracellular loop of FPR2, and it activates as well as desensensitizes this receptor. We now show that neutrophils...

  14. Development of CINPA1 analogs as novel and potent inverse agonists of constitutive androstane receptor

    OpenAIRE

    Lin, Wenwei; Yang, Lei; Chai, Sergio C.; Lu, Yan; Chen, Taosheng

    2015-01-01

    Constitutive androstane receptor (CAR, NR1I3) and pregnane X receptor (PXR, NR1I2) are master regulators of endobiotic and xenobiotic metabolism and disposition. Because CAR is constitutively active in certain cellular contexts, inhibiting CAR might reduce drug-induced hepatotoxicity and resensitize drug-resistant cancer cells to chemotherapeutic drugs. We recently reported a novel CAR inhibitor/inverse agonist CINPA1 (11). Here, we have obtained or designed 54 analogs of CINPA1 and used a ti...

  15. Reports of pathological gambling, hypersexuality, and compulsive shopping associated with dopamine receptor agonist drugs.

    Science.gov (United States)

    Moore, Thomas J; Glenmullen, Joseph; Mattison, Donald R

    2014-12-01

    Severe impulse control disorders involving pathological gambling, hypersexuality, and compulsive shopping have been reported in association with the use of dopamine receptor agonist drugs in case series and retrospective patient surveys. These agents are used to treat Parkinson disease, restless leg syndrome, and hyperprolactinemia. To analyze serious adverse drug event reports about these impulse control disorders received by the US Food and Drug Administration (FDA) and to assess the relationship of these case reports with the 6 FDA-approved dopamine receptor agonist drugs. We conducted a retrospective disproportionality analysis based on the 2.7 million serious domestic and foreign adverse drug event reports from 2003 to 2012 extracted from the FDA Adverse Event Reporting System. Cases were selected if they contained any of 10 preferred terms in the Medical Dictionary for Regulatory Activities (MedDRA) that described the abnormal behaviors. We used the proportional reporting ratio (PRR) to compare the proportion of target events to all serious events for the study drugs with a similar proportion for all other drugs. We identified 1580 events indicating impulse control disorders from the United States and 21 other countries:710 fordopamine receptor agonist drugs and 870 for other drugs. The dopamine receptor agonist drugs had a strong signal associated with these impulse control disorders (n = 710; PRR = 277.6, P < .001). The association was strongest for the dopamine agonists pramipexole (n = 410; PRR = 455.9, P < .001) and ropinirole (n = 188; PRR = 152.5, P < .001), with preferential affinity for the dopamine D3 receptor. A signal was also seen for aripiprazole, an antipsychotic classified as a partial agonist of the D3 receptor (n = 37; PRR = 8.6, P < .001). Our findings confirm and extend the evidence that dopamine receptor agonist drugs are associated with these specific impulse control disorders. At present

  16. Improving the developability profile of pyrrolidine progesterone receptor partial agonists

    Energy Technology Data Exchange (ETDEWEB)

    Kallander, Lara S.; Washburn, David G.; Hoang, Tram H.; Frazee, James S.; Stoy, Patrick; Johnson, Latisha; Lu, Qing; Hammond, Marlys; Barton, Linda S.; Patterson, Jaclyn R.; Azzarano, Leonard M.; Nagilla, Rakesh; Madauss, Kevin P.; Williams, Shawn P.; Stewart, Eugene L.; Duraiswami, Chaya; Grygielko, Eugene T.; Xu, Xiaoping; Laping, Nicholas J.; Bray, Jeffrey D.; Thompson, Scott K. (GSKPA)

    2010-09-17

    The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

  17. A Rationally Designed Agonist Defines Subfamily IIIA Abscisic Acid Receptors As Critical Targets for Manipulating Transpiration.

    Science.gov (United States)

    Vaidya, Aditya S; Peterson, Francis C; Yarmolinsky, Dmitry; Merilo, Ebe; Verstraeten, Inge; Park, Sang-Youl; Elzinga, Dezi; Kaundal, Amita; Helander, Jonathan; Lozano-Juste, Jorge; Otani, Masato; Wu, Kevin; Jensen, Davin R; Kollist, Hannes; Volkman, Brian F; Cutler, Sean R

    2017-11-17

    Increasing drought and diminishing freshwater supplies have stimulated interest in developing small molecules that can be used to control transpiration. Receptors for the plant hormone abscisic acid (ABA) have emerged as key targets for this application, because ABA controls the apertures of stomata, which in turn regulate transpiration. Here, we describe the rational design of cyanabactin, an ABA receptor agonist that preferentially activates Pyrabactin Resistance 1 (PYR1) with low nanomolar potency. A 1.63 Å X-ray crystallographic structure of cyanabactin in complex with PYR1 illustrates that cyanabactin's arylnitrile mimics ABA's cyclohexenone oxygen and engages the tryptophan lock, a key component required to stabilize activated receptors. Further, its sulfonamide and 4-methylbenzyl substructures mimic ABA's carboxylate and C6 methyl groups, respectively. Isothermal titration calorimetry measurements show that cyanabactin's compact structure provides ready access to high ligand efficiency on a relatively simple scaffold. Cyanabactin treatments reduce Arabidopsis whole-plant stomatal conductance and activate multiple ABA responses, demonstrating that its in vitro potency translates to ABA-like activity in vivo. Genetic analyses show that the effects of cyanabactin, and the previously identified agonist quinabactin, can be abolished by the genetic removal of PYR1 and PYL1, which form subclade A within the dimeric subfamily III receptors. Thus, cyanabactin is a potent and selective agonist with a wide spectrum of ABA-like activities that defines subfamily IIIA receptors as key target sites for manipulating transpiration.

  18. The GABAA receptor agonist THIP is neuroprotective in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, Jens; Zimmer, Jens

    2003-01-01

    The potential neuroprotective effects of the GABA(A) receptor agonists THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and muscimol, and the selective GluR5 kainate receptor agonist ATPA ((RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid), which activates GABAergic interneu......The potential neuroprotective effects of the GABA(A) receptor agonists THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and muscimol, and the selective GluR5 kainate receptor agonist ATPA ((RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid), which activates GABAergic...... interneurons, were examined in hippocampal slice cultures exposed to N-methyl-D-aspartate (NMDA). The NMDA-induced excitotoxicity was quantified by densitometric measurements of propidium iodide (PI) uptake. THIP (100-1000 microM) was neuroprotective in slice cultures co-exposed to NMDA (10 microM) for 48 h......, while muscimol (100-1000 microM) and ATPA (1-3 microM) were without effect. The results demonstrate that direct GABA(A) agonism can mediate neuroprotection in the hippocampus in vitro as previously suggested in vivo....

  19. Modulation of Female Genital Tract-Derived Dendritic Cell Migration and Activation in Response to Inflammatory Cytokines and Toll-Like Receptor Agonists.

    Science.gov (United States)

    Shey, Muki S; Maharaj, Niren; Archary, Derseree; Ngcapu, Sinaye; Garrett, Nigel; Abdool Karim, Salim; Passmore, Jo-Ann S

    2016-01-01

    HIV transmission across the genital mucosa is a major mode of new HIV infections in women. The probability of infection may be influenced by several factors including recruitment and activation of HIV target cells, such as dendritic cells (DCs) and cytokine production, associated with genital inflammation. We evaluated the role of inflammatory cytokines and TLR signaling in migration and activation of genital tract DCs in the human cervical explant model. Hysterectomy tissues from 10 HIV-negative and 7 HIV-positive donor women were separated into ecto- and endocervical explants, and incubated with inflammatory cytokines (TNF-α, IL-1β, IL-8, MIP-1β) or agonists for TLR4 (LPS), TLR2/1 (PAM3) and TLR7/8 (R848). Migration (frequency) and activation (HLA-DR expression) of myeloid and plasmacytoid DCs and Langerhans cells were measured by flow cytometry. We observed that cytokines, LPS and PAM3 induced activation of migrating myeloid and plasmacytoid DCs. LPS induced a 3.6 fold lower levels of migration of plasmacytoid DCs from HIV-infected women compared with HIV-uninfected women (median activation indices of 2.932 vs 0.833). There was however a 4.5 fold increase in migration of Langerhans cells in HIV-infected compared with HIV-uninfected women in response to cytokines (median activation indices of 3.539 vs 0.77). Only TLR agonists induced migration and activation of DCs from endocervical explants. Hormonal contraception use was associated with an increase in activation of DC subsets in the endo and ectocervical explants. We conclude that inflammatory signals in the female genital tract induced DC migration and activation, with possible important implications for HIV susceptibility of cervical tissues.

  20. Modulation of Female Genital Tract-Derived Dendritic Cell Migration and Activation in Response to Inflammatory Cytokines and Toll-Like Receptor Agonists.

    Directory of Open Access Journals (Sweden)

    Muki S Shey

    Full Text Available HIV transmission across the genital mucosa is a major mode of new HIV infections in women. The probability of infection may be influenced by several factors including recruitment and activation of HIV target cells, such as dendritic cells (DCs and cytokine production, associated with genital inflammation. We evaluated the role of inflammatory cytokines and TLR signaling in migration and activation of genital tract DCs in the human cervical explant model. Hysterectomy tissues from 10 HIV-negative and 7 HIV-positive donor women were separated into ecto- and endocervical explants, and incubated with inflammatory cytokines (TNF-α, IL-1β, IL-8, MIP-1β or agonists for TLR4 (LPS, TLR2/1 (PAM3 and TLR7/8 (R848. Migration (frequency and activation (HLA-DR expression of myeloid and plasmacytoid DCs and Langerhans cells were measured by flow cytometry. We observed that cytokines, LPS and PAM3 induced activation of migrating myeloid and plasmacytoid DCs. LPS induced a 3.6 fold lower levels of migration of plasmacytoid DCs from HIV-infected women compared with HIV-uninfected women (median activation indices of 2.932 vs 0.833. There was however a 4.5 fold increase in migration of Langerhans cells in HIV-infected compared with HIV-uninfected women in response to cytokines (median activation indices of 3.539 vs 0.77. Only TLR agonists induced migration and activation of DCs from endocervical explants. Hormonal contraception use was associated with an increase in activation of DC subsets in the endo and ectocervical explants. We conclude that inflammatory signals in the female genital tract induced DC migration and activation, with possible important implications for HIV susceptibility of cervical tissues.

  1. Effect of ghrelin receptor agonist and antagonist on the activity of arcuate nucleus tyrosine hydroxylase containing neurons in C57BL/6 male mice exposed to normal or high fat diet

    Czech Academy of Sciences Publication Activity Database

    Pirník, Z.; Majerčíková, Z.; Holubová, Martina; Pirník, R.; Železná, Blanka; Maletínská, Lenka; Kiss, A.

    2014-01-01

    Roč. 65, č. 4 (2014), s. 477-486 ISSN 0867-5910 Institutional support: RVO:61388963 Keywords : growth hormone secretagogue receptor * ghrelin receptor agonist * ghrelin receptor antagonist * high fat diet * tyrosine hydroxylase * arcuate nucleus * food intake Subject RIV: CE - Biochemistry Impact factor: 2.386, year: 2014

  2. The therapeutic potential of nicotinic acetylcholine receptor agonists for pain control.

    Science.gov (United States)

    Decker, M W; Meyer, M D; Sullivan, J P

    2001-10-01

    Due to the limitations of currently available analgesics, a number of novel alternatives are currently under investigation, including neuronal nicotinic acetylcholine receptor (nAChR) agonists. During the 1990s, the discovery of the antinociceptive properties of the potent nAChR agonist epibatidine in rodents sparked interest in the analgesic potential of this class of compounds. Although epibatidine also has several mechanism-related toxicities, the identification of considerable nAChR diversity suggested that the toxicities and therapeutic actions of the compound might be mediated by distinct receptor subtypes. Consistent with this view, a number of novel nAChR agonists with antinociceptive activity and improved safety profiles in preclinical models have now been identified, including A-85380, ABT-594, DBO-83, SIB-1663 and RJR-2403. Of these, ABT-594 is the most advanced and is currently in Phase II clinical evaluation. Nicotinically-mediated antinociception has been demonstrated in a variety of rodent pain models and is likely mediated by the activation of descending inhibitory pathways originating in the brainstem with the predominant high-affinity nicotine site in brain, the alpha4beta2 subtype, playing a critical role. Thus, preclinical findings suggest that nAChR agonists have the potential to be highly efficacious treatments in a variety of pain states. However, clinical proof-of-principle studies will be required to determine if nAChR agonists are active in pathological pain.

  3. Sigma-1 receptor agonists directly inhibit Nav1.2/1.4 channels.

    Directory of Open Access Journals (Sweden)

    Xiao-Fei Gao

    Full Text Available (+-SKF 10047 (N-allyl-normetazocine is a prototypic and specific sigma-1 receptor agonist that has been used extensively to study the function of sigma-1 receptors. (+-SKF 10047 inhibits K(+, Na(+ and Ca2+ channels via sigma-1 receptor activation. We found that (+-SKF 10047 inhibited Na(V1.2 and Na(V1.4 channels independently of sigma-1 receptor activation. (+-SKF 10047 equally inhibited Na(V1.2/1.4 channel currents in HEK293T cells with abundant sigma-1 receptor expression and in COS-7 cells, which barely express sigma-1 receptors. The sigma-1 receptor antagonists BD 1063,BD 1047 and NE-100 did not block the inhibitory effects of (+-SKF-10047. Blocking of the PKA, PKC and G-protein pathways did not affect (+-SKF 10047 inhibition of Na(V1.2 channel currents. The sigma-1 receptor agonists Dextromethorphan (DM and 1,3-di-o-tolyl-guanidine (DTG also inhibited Na(V1.2 currents through a sigma-1 receptor-independent pathway. The (+-SKF 10047 inhibition of Na(V1.2 currents was use- and frequency-dependent. Point mutations demonstrated the importance of Phe(1764 and Tyr(1771 in the IV-segment 6 domain of the Na(V1.2 channel and Phe(1579 in the Na(V1.4 channel for (+-SKF 10047 inhibition. In conclusion, our results suggest that sigma-1 receptor agonists directly inhibit Na(V1.2/1.4 channels and that these interactions should be given special attention for future sigma-1 receptor function studies.

  4. Dopamine agonist activity of EMD 23,448

    Energy Technology Data Exchange (ETDEWEB)

    Martin, G E; Pettibone, D J [Merck Sharp and Dohme Research Laboratories, West Point, Pennsylvania (USA). Dept. of Pharmacology

    1985-01-01

    EMD 23,448 was examined in tests of dopaminergic function and was found to be an atypical dopamine (DA) agonist. EMD 23,448 was a weak or inactive DA agonist when examined in tests of normal postsynaptic DA receptor function: production of stereotypy in the rat (ED/sub 50/ greater than sign 5.0 mg/kg.i.p.); production of emesis in beagles (minimum effective dose = 81..mu..g/kg i.v.); and, enhanced locomotor activity of the mouse (no excitation in doses <=50 mg/i.p.). Moreover, EMD 23,448 was relatively weak in competing for (/sup 3/H)-apomorphine binding to rat striatal membranes (Ki, 205 nM). On the other hand, this indolyl-3-butylamine did activate supersensitive postsynaptic DA receptors. Specifically, it elicited contralateral turning in rats with a unilateral 6-hydroxydopamine lesion of the substantia nigra (ED/sub 50/ value = 0.9 mg/kg) and did elicit stereotypy in rats given chronic daily haloperidol treatments. EMD 23,448 also exerted pharmacological effects in tests designed to measure activation of dopamine autoreceptors. It inhibited the ..gamma..-butyrolactone-induced increase in striatal dopa levels (ED/sub 50/ = 1 mg/kg i.p.) and produced a dose-related fall in the locomotor activity of the mouse. The results are discussed and contrasted with data derived for apomorphine and the putatively selective autoreceptor agonist (+-)-3-PPP.

  5. Dopamine agonist activity of EMD 23,448

    International Nuclear Information System (INIS)

    Martin, G.E.; Pettibone, D.J.

    1985-01-01

    EMD 23,448 was examined in tests of dopaminergic function and was found to be an atypical dopamine (DA) agonist. EMD 23,448 was a weak or inactive DA agonist when examined in tests of normal postsynaptic DA receptor function: production of stereotypy in the rat (ED 50 greater than sign 5.0 mg/kg.i.p.); production of emesis in beagles (minimum effective dose = 81μg/kg i.v.); and, enhanced locomotor activity of the mouse (no excitation in doses 3 H]-apomorphine binding to rat striatal membranes (Ki, 205 nM). On the other hand, this indolyl-3-butylamine did activate supersensitive postsynaptic DA receptors. Specifically, it elicited contralateral turning in rats with a unilateral 6-hydroxydopamine lesion of the substantia nigra (ED 50 value = 0.9 mg/kg) and did elicit stereotypy in rats given chronic daily haloperidol treatments. EMD 23,448 also exerted pharmacological effects in tests designed to measure activation of dopamine autoreceptors. It inhibited the γ-butyrolactone-induced increase in striatal dopa levels (ED 50 = 1 mg/kg i.p.) and produced a dose-related fall in the locomotor activity of the mouse. The results are discussed and contrasted with data derived for apomorphine and the putatively selective autoreceptor agonist (+-)-3-PPP. (Author)

  6. High constitutive signaling of the ghrelin receptor--identification of a potent inverse agonist

    DEFF Research Database (Denmark)

    Holst, Birgitte; Cygankiewicz, Adam; Jensen, Tine Halkjaer

    2003-01-01

    Ghrelin is a GH-releasing peptide that also has an important role as an orexigenic hormone-stimulating food intake. By measuring inositol phosphate turnover or by using a reporter assay for transcriptional activity controlled by cAMP-responsive elements, the ghrelin receptor showed strong, ligand......-independent signaling in transfected COS-7 or human embryonic kidney 293 cells. Ghrelin and a number of the known nonpeptide GH secretagogues acted as agonists stimulating inositol phosphate turnover further. In contrast, the low potency ghrelin antagonist, [D-Arg1,D-Phe5,D-Trp7,9,Leu11]-substance P was surprisingly...... found to be a high potency (EC50 = 5.2 nm) full inverse agonist as it decreased the constitutive signaling of the ghrelin receptor down to that observed in untransfected cells. The homologous motilin receptor functioned as a negative control as it did not display any sign of constitutive activity...

  7. Homologous histamine H1 receptor desensitization results in reduction of H1 receptor agonist efficacy

    NARCIS (Netherlands)

    Leurs, R; Smit, M J; Bast, A; Timmerman, H

    1991-01-01

    Prolonged exposure of the guinea-pig intestinal longitudinal smooth muscle to histamine caused homologous desensitization of the H1 receptor, which led to reduced H1 receptor-mediated production of [3H]inositol phosphates as well as to reduced H1 agonist-induced contractions. [3H]Mepyramine binding

  8. SB265610 is an allosteric, inverse agonist at the human CXCR2 receptor

    Science.gov (United States)

    Bradley, ME; Bond, ME; Manini, J; Brown, Z; Charlton, SJ

    2009-01-01

    Background and purpose: In several previous studies, the C-X-C chemokine receptor (CXCR)2 antagonist 1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea (SB265610) has been described as binding competitively with the endogenous agonist. This is in contrast to many other chemokine receptor antagonists, where the mechanism of antagonism has been described as allosteric. Experimental approach: To determine whether it displays a unique mechanism among the chemokine receptor antagonists, the mode of action of SB265610 was investigated at the CXCR2 receptor using radioligand and [35S]-GTPγS binding approaches in addition to chemotaxis of human neutrophils. Key results: In equilibrium saturation binding studies, SB265610 depressed the maximal binding of [125I]-interleukin-8 ([125I]-IL-8) without affecting the Kd. In contrast, IL-8 was unable to prevent binding of [3H]-SB265610. Kinetic binding experiments demonstrated that this was not an artefact of irreversible or slowly reversible binding. In functional experiments, SB265610 caused a rightward shift of the concentration-response curves to IL-8 and growth-related oncogene α, but also a reduction in maximal response elicited by each agonist. Fitting these data to an operational allosteric ternary complex model suggested that, once bound, SB265610 completely blocks receptor activation. SB265610 also inhibited basal [35S]-GTPγS binding in this preparation. Conclusions and implications: Taken together, these data suggest that SB265610 behaves as an allosteric inverse agonist at the CXCR2 receptor, binding at a region distinct from the agonist binding site to prevent receptor activation, possibly by interfering with G protein coupling. PMID:19422399

  9. Distinct Signaling Cascades Elicited by Different Formyl Peptide Receptor 2 (FPR2 Agonists

    Directory of Open Access Journals (Sweden)

    Fabio Cattaneo

    2013-04-01

    Full Text Available The formyl peptide receptor 2 (FPR2 is a remarkably versatile transmembrane protein belonging to the G-protein coupled receptor (GPCR family. FPR2 is activated by an array of ligands, which include structurally unrelated lipids and peptide/proteins agonists, resulting in different intracellular responses in a ligand-specific fashion. In addition to the anti-inflammatory lipid, lipoxin A4, several other endogenous agonists also bind FPR2, including serum amyloid A, glucocorticoid-induced annexin 1, urokinase and its receptor, suggesting that the activation of FPR2 may result in potent pro- or anti-inflammatory responses. Other endogenous ligands, also present in biological samples, include resolvins, amyloidogenic proteins, such as beta amyloid (Aβ-42 and prion protein (Prp106–126, the neuroprotective peptide, humanin, antibacterial peptides, annexin 1-derived peptides, chemokine variants, the neuropeptides, vasoactive intestinal peptide (VIP and pituitary adenylate cyclase activating polypeptide (PACAP-27, and mitochondrial peptides. Upon activation, intracellular domains of FPR2 mediate signaling to G-proteins, which trigger several agonist-dependent signal transduction pathways, including activation of phospholipase C (PLC, protein kinase C (PKC isoforms, the phosphoinositide 3-kinase (PI3K/protein kinase B (Akt pathway, the mitogen-activated protein kinase (MAPK pathway, p38MAPK, as well as the phosphorylation of cytosolic tyrosine kinases, tyrosine kinase receptor transactivation, phosphorylation and nuclear translocation of regulatory transcriptional factors, release of calcium and production of oxidants. FPR2 is an attractive therapeutic target, because of its involvement in a range of normal physiological processes and pathological diseases. Here, we review and discuss the most significant findings on the intracellular pathways and on the cross-communication between FPR2 and tyrosine kinase receptors triggered by different FPR2

  10. The delta-opioid receptor agonist SNC80 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-(3-methoxybenzyl)-N,N-diethylbenzamide] synergistically enhances the locomotor-activating effects of some psychomotor stimulants, but not direct dopamine agonists, in rats.

    Science.gov (United States)

    Jutkiewicz, Emily M; Baladi, Michelle G; Folk, John E; Rice, Kenner C; Woods, James H

    2008-02-01

    The nonpeptidic delta-opioid agonist SNC80 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-(3-methoxybenzyl)-N,N-diethylbenzamide] produces many stimulant-like behavioral effects in rodents and monkeys, such as locomotor stimulation, generalization to cocaine in discrimination procedures, and antiparkinsonian effects. Tolerance to the locomotor-stimulating effects of SNC80 develops after a single administration of SNC80 in rats; it is not known whether cross-tolerance develops to the effects of other stimulant compounds. In the initial studies to determine whether SNC80 produced cross-tolerance to other stimulant compounds, it was discovered that amphetamine-stimulated locomotor activity was greatly enhanced in SNC80-pretreated rats. This study evaluated acute cross-tolerance between delta-opioid agonists and other locomotor-stimulating drugs. Locomotor activity was measured in male Sprague-Dawley rats implanted with radiotransmitters, and activity levels were recorded in the home cage environment. Three-hour SNC80 pretreatment produced tolerance to further delta-opioid receptor stimulation but also augmented greatly amphetamine-stimulated locomotor activity in a dose-dependent manner. Pretreatments with other delta-opioid agonists, (+)BW373U86 [(+)-4-[alpha(R)-alpha-[(2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl]-3-hydroxybenzyl]-N,N-diethylbenzamide] and oxymorphindole (17-methyl-6,7-dehydro-4,5-epoxy-3,14-dihydroxy-6,7,2',3'-indolomorphinan), also modified amphetamine-induced activity levels. SNC80 pretreatment enhanced the stimulatory effects of the dopamine/norepinephrine transporter ligands cocaine and nomifensine (1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-isoquinolinanmine maleate salt), but not the direct dopamine receptor agonists SKF81297 [R-(+)-6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide] and quinpirole [trans-(-)-(4alphaR)-4,4a, 5,6,7,8,8a,9-octahydro-5-propyl-1H-pyrazolo[3,4-g] quinoline

  11. Synergistic Anti-Tumor Activity of EZH2 Inhibitors and Glucocorticoid Receptor Agonists in Models of Germinal Center Non-Hodgkin Lymphomas.

    Directory of Open Access Journals (Sweden)

    Sarah K Knutson

    Full Text Available Patients with non-Hodgkin lymphoma (NHL are treated today with a cocktail of drugs referred to as CHOP (Cyclophosphamide, Hydroxyldaunorubicin, Oncovin, and Prednisone. Subsets of patients with NHL of germinal center origin bear oncogenic mutations in the EZH2 histone methyltransferase. Clinical testing of the EZH2 inhibitor EPZ-6438 has recently begun in patients. We report here that combining EPZ-6438 with CHOP in preclinical cell culture and mouse models results in dramatic synergy for cell killing in EZH2 mutant germinal center NHL cells. Surprisingly, we observe that much of this synergy is due to Prednisolone - a glucocorticoid receptor agonist (GRag component of CHOP. Dramatic synergy was observed when EPZ-6438 is combined with Prednisolone alone, and a similar effect was observed with Dexamethasone, another GRag. Remarkably, the anti-proliferative effect of the EPZ-6438+GRag combination extends beyond EZH2 mutant-bearing cells to more generally impact germinal center NHL. These preclinical data reveal an unanticipated biological intersection between GR-mediated gene regulation and EZH2-mediated chromatin remodeling. The data also suggest the possibility of a significant and practical benefit of combining EZH2 inhibitors and GRag that warrants further investigation in a clinical setting.

  12. Synergistic Anti-Tumor Activity of EZH2 Inhibitors and Glucocorticoid Receptor Agonists in Models of Germinal Center Non-Hodgkin Lymphomas.

    Science.gov (United States)

    Knutson, Sarah K; Warholic, Natalie M; Johnston, L Danielle; Klaus, Christine R; Wigle, Tim J; Iwanowicz, Dorothy; Littlefield, Bruce A; Porter-Scott, Margaret; Smith, Jesse J; Moyer, Mikel P; Copeland, Robert A; Pollock, Roy M; Kuntz, Kevin W; Raimondi, Alejandra; Keilhack, Heike

    2014-01-01

    Patients with non-Hodgkin lymphoma (NHL) are treated today with a cocktail of drugs referred to as CHOP (Cyclophosphamide, Hydroxyldaunorubicin, Oncovin, and Prednisone). Subsets of patients with NHL of germinal center origin bear oncogenic mutations in the EZH2 histone methyltransferase. Clinical testing of the EZH2 inhibitor EPZ-6438 has recently begun in patients. We report here that combining EPZ-6438 with CHOP in preclinical cell culture and mouse models results in dramatic synergy for cell killing in EZH2 mutant germinal center NHL cells. Surprisingly, we observe that much of this synergy is due to Prednisolone - a glucocorticoid receptor agonist (GRag) component of CHOP. Dramatic synergy was observed when EPZ-6438 is combined with Prednisolone alone, and a similar effect was observed with Dexamethasone, another GRag. Remarkably, the anti-proliferative effect of the EPZ-6438+GRag combination extends beyond EZH2 mutant-bearing cells to more generally impact germinal center NHL. These preclinical data reveal an unanticipated biological intersection between GR-mediated gene regulation and EZH2-mediated chromatin remodeling. The data also suggest the possibility of a significant and practical benefit of combining EZH2 inhibitors and GRag that warrants further investigation in a clinical setting.

  13. N-methyl-D-aspartic acid receptor agonists

    DEFF Research Database (Denmark)

    Madsen, U; Frydenvang, Karla Andrea; Ebert, B

    1996-01-01

    (R,S)-2-Amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid [(R,S)-AMAA, 4] is a potent and selective agonist at the N-methyl-D-aspartic acid (NMDA) subtype of excitatory amino acid receptors. Using the Ugi "four-component condensation" method, the two diastereomers (2R)- and (2S)-2-[3-(benzyloxy......) showed peak affinity for [3H]AMPA receptor sites (IC50 = 72 +/- 13 microM) and was shown to be a more potent inhibitor of [3H]CPP binding (IC50 = 3.7 +/- 1.5 microM) than (S)-AMAA (9) (IC50 = 61 +/- 6.4 microM). Neither enantiomer of AMAA affected [3H]kainic acid receptor binding significantly...

  14. The nicotinic alpha7 acetylcholine receptor agonist ssr180711 is unable to activate limbic neurons in mice overexpressing human amyloid-beta1-42

    DEFF Research Database (Denmark)

    Soderman, A.; Spang-Thomsen, Mogens; Hansen, H.

    2008-01-01

    Recent studies have demonstrated that amyloid-beta1-42 (Abeta1-42) binds to the nicotinergic alpha7 acetylcholine receptor (alpha7 nAChR) and that the application of Abeta1-42 to cells inhibits the function of the alpha7 nAChR. The in vivo consequences of the pharmacological activation of the alp...

  15. The fibroblast growth factor receptor (FGFR) agonist FGF1 and the neural cell adhesion molecule-derived peptide FGL activate FGFR substrate 2alpha differently

    DEFF Research Database (Denmark)

    Chen, Yongshuo; Li, Shizhong; Berezin, Vladimir

    2010-01-01

    Activation of fibroblast growth factor (FGF) receptors (FGFRs) both by FGFs and by the neural cell adhesion molecule (NCAM) is crucial in the development and function of the nervous system. We found that FGFR substrate 2alpha (FRS2alpha), Src homologous and collagen A (ShcA), and phospholipase-Cg...

  16. Overlapping binding site for the endogenous agonist, small-molecule agonists, and ago-allosteric modulators on the ghrelin receptor

    DEFF Research Database (Denmark)

    Holst, Birgitte; Frimurer, Thomas M; Mokrosinski, Jacek

    2008-01-01

    A library of robust ghrelin receptor mutants with single substitutions at 22 positions in the main ligand-binding pocket was employed to map binding sites for six different agonists: two peptides (the 28-amino-acid octanoylated endogenous ligand ghrelin and the hexapeptide growth hormone......, and PheVI:23 on the opposing face of transmembrane domain (TM) VI. Each of the agonists was also affected selectively by specific mutations. The mutational map of the ability of L-692,429 and GHRP-6 to act as allosteric modulators by increasing ghrelin's maximal efficacy overlapped with the common....... It is concluded that although each of the ligands in addition exploits other parts of the receptor, a large, common binding site for both small-molecule agonists--including ago-allosteric modulators--and the endogenous agonist is found on the opposing faces of TM-III and -VI of the ghrelin receptor....

  17. Exploring the binding energy profiles of full agonists, partial agonists, and antagonists of the α7 nicotinic acetylcholine receptor.

    Science.gov (United States)

    Tabassum, Nargis; Ma, Qianyun; Wu, Guanzhao; Jiang, Tao; Yu, Rilei

    2017-09-01

    Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop receptor family and are important drug targets for the treatment of neurological diseases. However, the precise determinants of the binding efficacies of ligands for these receptors are unclear. Therefore, in this study, the binding energy profiles of various ligands (full agonists, partial agonists, and antagonists) were quantified by docking those ligands with structural ensembles of the α7 nAChR exhibiting different degrees of C-loop closure. This approximate treatment of interactions suggested that full agonists, partial agonists, and antagonists of the α7 nAChR possess distinctive binding energy profiles. Results from docking revealed that ligand binding efficacy may be related to the capacity of the ligand to stabilize conformational states with a closed C loop.

  18. Detection of glucocorticoid receptor agonists in effluents from sewage treatment plants in Japan.

    Science.gov (United States)

    Suzuki, Go; Sato, Kentaro; Isobe, Tomohiko; Takigami, Hidetaka; Brouwer, Abraham; Nakayama, Kei

    2015-09-15

    Glucocorticoids (GCs) are widely used as anti-inflammatory drugs. Our previous study demonstrated that several GCs such as cortisol and dexamethasone (Dex) were frequently detected in effluents collected from Japanese sewage treatment plants (STPs) in 2012. In this study, we used the GC-Responsive Chemical-Activated LUciferase gene eXpression (GR-CALUX) assay to elucidate GC receptor (GR) agonistic activities of ten pure synthetic GCs and selected STP effluents in Japan for assessment of the risks associated with the presence of GR agonists. The tested GCs demonstrated dose-dependent agonistic effects in the GR-CALUX assay and their EC50 values were calculated for estimation of relative potencies (REPs) compared to Dex. The GR agonistic potency was in the rank of: clobetasol propionate > clobetasone butyrate > betamethasone 17-valerate > difluprednate > betamethasone 17,21-dipropionate > Dex > betamethasone > 6α-methylprednisolone > prednisolone > cortisol. The GR agonistic activity in STP effluents as measured in Dex-equivalent (Dex-EQ) activities ranged from effluents in Japan. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Melanocortin Receptor Agonists Facilitate Oxytocin-Dependent Partner Preference Formation in the Prairie Vole.

    Science.gov (United States)

    Modi, Meera E; Inoue, Kiyoshi; Barrett, Catherine E; Kittelberger, Kara A; Smith, Daniel G; Landgraf, Rainer; Young, Larry J

    2015-07-01

    The central melanocortin (MC) system has been widely studied for its effects on food intake and sexual behavior. However, the MC system, and more specifically the MC4 receptor (MC4R), also interacts with neurochemical systems that regulate socioemotional behaviors, including oxytocin (OT) and dopamine. In monogamous prairie voles, OT and dopamine interact to promote partner preference formation, a laboratory measure of an enduring social bond between mates. Here we investigated the effects of MC receptor activation on partner preference formation in prairie voles, as well as the interaction between the MC and OT systems during this process. Peripheral administration of the brain penetrant MC3/4R receptor peptide agonist, Melanotan II (MTII), and the highly selective, small-molecule MC4R agonist, Pf-446687, enhanced partner preference formation in the prairie vole, but not in the non-monogamous meadow vole. MTII-induced partner preferences were enduring, as they were present 1 week after drug manipulation. The prosocial effects of MCR agonists may be mediated, in part, through modulation of OT, as coadministration of an OT receptor antagonist prevented MTII-induced partner preferences. MTII also selectively activated hypothalamic OT neurons and potentiated central OT release. As OT has been shown to enhance some aspects of social cognition in humans, our data suggest that the MC4R may be a viable therapeutic target for enhancing social function in psychiatric disorders, including autism spectrum disorders and schizophrenia, potentially through activation of the OT system.

  20. Cardiovascular safety and benefits of GLP-1 receptor agonists

    DEFF Research Database (Denmark)

    Dalsgaard, Niels B; Brønden, Andreas; Lauritsen, Tina Vilsbøll

    2017-01-01

    INTRODUCTION: Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) constitute a class of drugs for the treatment of type 2 diabetes, and currently, six different GLP-1RAs are approved. Besides improving glycemic control, the GLP-1RAs have other beneficial effects such as weight loss...... and a low risk of hypoglycemia. Treatment with the GLP-1RA lixisenatide has been shown to be safe in patients with type 2 diabetes and recent acute coronary syndrome. Furthermore, liraglutide and semaglutide have been shown to reduce cardiovascular (CV) disease (CVD) risk in type 2 diabetes patients...

  1. Development of CINPA1 analogs as novel and potent inverse agonists of constitutive androstane receptor.

    Science.gov (United States)

    Lin, Wenwei; Yang, Lei; Chai, Sergio C; Lu, Yan; Chen, Taosheng

    2016-01-27

    Constitutive androstane receptor (CAR, NR1I3) and pregnane X receptor (PXR, NR1I2) are master regulators of endobiotic and xenobiotic metabolism and disposition. Because CAR is constitutively active in certain cellular contexts, inhibiting CAR might reduce drug-induced hepatotoxicity and resensitize drug-resistant cancer cells to chemotherapeutic drugs. We recently reported a novel CAR inhibitor/inverse agonist CINPA1 (11). Here, we have obtained or designed 54 analogs of CINPA1 and used a time-resolved fluorescence resonance energy transfer (TR-FRET) assay to evaluate their CAR inhibition potency. Many of the 54 analogs showed CAR inverse agonistic activities higher than those of CINPA1, which has an IC50 value of 687 nM. Among them, 72 has an IC50 value of 11.7 nM, which is about 59-fold more potent than CINPA1 and over 10-fold more potent than clotrimazole (an IC50 value of 126.9 nM), the most potent CAR inverse agonist in a biochemical assay previously reported by others. Docking studies provide a molecular explanation of the structure-activity relationship (SAR) observed experimentally. To our knowledge, this effort is the first chemistry endeavor in designing and identifying potent CAR inverse agonists based on a novel chemical scaffold, leading to 72 as the most potent CAR inverse agonist so far. The 54 chemicals presented are novel and unique tools for characterizing CAR's function, and the SAR information gained from these 54 analogs could guide future efforts to develop improved CAR inverse agonists. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  2. Interleukin-24 as a target cytokine of environmental aryl hydrocarbon receptor agonist exposure in the lung

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yueh-Hsia; Kuo, Yu-Chun; Tsai, Ming-Hsien; Ho, Chia-Chi; Tsai, Hui-Ti; Hsu, Chin-Yu; Chen, Yu-Cheng; Lin, Pinpin, E-mail: pplin@nhri.org.tw

    2017-06-01

    Exposure to environmental aryl hydrocarbon receptor (AhR) agonists, such as halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), has great impacts on the development of various lung diseases. As emerging molecular targets for AhR agonists, cytokines may contribute to the inflammatory or immunotoxic effects of environmental AhR agonists. However, general cytokine expression may not specifically indicate environmental AhR agonist exposure. By comparing cytokine and chemokine expression profiles in human lung adenocarcinoma cell line CL5 treated with AhR agonists and the non-AhR agonist polychlorinated biphenyl (PCB) 39, we identified a target cytokine of environmental AhR agonist exposure of in the lungs. Thirteen cytokine and chemokine genes were altered in the AhR agonists-treated cells, but none were altered in the PCB39-treated cells. Interleukin (IL)-24 was the most highly induced gene among AhR-modulated cytokines. Cotreatment with AhR antagonist completely prevented IL-24 induction by AhR agonists in the CL5 cells. Knockdown AhR expression with short-hairpin RNA (shRNA) significantly reduced benzo[a]pyrene (BaP)-induced IL-24 mRNA levels. We further confirmed that gene transcription, but not mRNA stability, was involved in IL-24 upregulation by BaP. Particulate matter (PM) in the ambient air contains some PAHs and is reported to activate AhR. Oropharyngeal aspiration of PM significantly increased IL-24 levels in lung epithelia and in bronchoalveolar lavage fluid of mice 4 weeks after treatment. Thus, our data suggests that IL-24 is a pulmonary exposure target cytokine of environmental AhR agonists. - Graphical abstract: (A) Cytokine and chemokine gene expressions were examined in CL5 cells treated with AhR and non-AhR agonists. Thirteen cytokines and chemokines genes were altered in the AhR agonist-treated cells, but not in the non-AhR agonist-treated cells. IL-24 was the most highly induced gene among the AhR-modulated cytokines. (B

  3. Conversion of agonist site to metal-ion chelator site in the beta(2)-adrenergic receptor

    DEFF Research Database (Denmark)

    Elling, C E; Thirstrup, K; Holst, Birgitte

    1999-01-01

    Previously metal-ion sites have been used as structural and functional probes in seven transmembrane receptors (7TM), but as yet all the engineered sites have been inactivating. Based on presumed agonist interaction points in transmembrane III (TM-III) and -VII of the beta(2)-adrenergic receptor,...... as generic, pharmacologic tools to switch 7TM receptors with engineered metal-ion sites on or off at will.......Previously metal-ion sites have been used as structural and functional probes in seven transmembrane receptors (7TM), but as yet all the engineered sites have been inactivating. Based on presumed agonist interaction points in transmembrane III (TM-III) and -VII of the beta(2)-adrenergic receptor......, in this paper we construct an activating metal-ion site between the amine-binding Asp-113 in TM-III-or a His residue introduced at this position-and a Cys residue substituted for Asn-312 in TM-VII. No increase in constitutive activity was observed in the mutant receptors. Signal transduction was activated...

  4. Quantitative phosphoproteomics dissection of 7TM receptor signaling using full and biased agonists

    DEFF Research Database (Denmark)

    Christensen, Gitte L; Kelstrup, Christian D; Lyngsø, Christina

    2010-01-01

    only activates the Gaq protein-independent signaling.e quantified more than ten thousand phosphorylation sites of which 1183 were regulated by Angiotensin II or its analogue SII Angiotensin II. 36% of the AT1R regulated phosphorylations were regulated by SII Angiotensin II. Analysis of phosphorylation...... into Angiotensin II signal transduction and is the first study dissecting the differences between a full agonist and a biased agonist from a 7TMR on a systems-wide scale. Importantly, it reveals a previously unappreciated diversity and quantity of Gaq protein-independent signaling and uncovers novel signaling......Seven-transmembrane receptors (7TMRs) signal through the well described heterotrimeric G proteins, but can also activate G protein-independent signaling pathways of which the impact and complexity are less understood. The Angiotensin II type 1 receptor (AT1R) is a prototypical 7TMR and an important...

  5. [Safety and tolerability of GLP-1 receptor agonists].

    Science.gov (United States)

    Soldevila, Berta; Puig-Domingo, Manel

    2014-09-01

    Glucagon-like peptide-1 receptor agonists (GLP-1ra) are a new group of drugs with a glucose-lowering action due to their incretin effect. The GLP-1 receptor is expressed in various human tissues, which could be related to the pleiotropic effects of human GLP-1, as well as to the adverse effects described in patients treated with GLP-1ra. The risk of hypoglycaemia is low, which is one of the main considerations in the safety of this family of compounds and is also important to patients with diabetes. The most frequent adverse effect is nausea, which usually occurs at the start of treatment and is transient in 20-60% of affected patients. This article also reviews the information available on antibody formation, the potential effect on the thyroid gland, and the controversial association between this group of drugs with pancreatitis and cancer. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

  6. Group III mGlu receptor agonists potentiate the anticonvulsant effect of AMPA and NMDA receptor block.

    Science.gov (United States)

    De Sarro, Giovambattista; Chimirri, Alba; Meldrum, Brian S

    2002-09-06

    We report the anticonvulsant action in DBA/2 mice of two mGlu Group III receptor agonists: (R,S)-4-phosphonophenylglycine, (R,S)-PPG, a compound with moderate mGlu8 selectivity, and of (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid, ACPT-1, a selective agonist for mGlu4alpha receptors. Both compounds, given intracerebroventricularly at doses which did not show marked anticonvulsant activity, produced a consistent shift to the left of the dose-response curves (i.e. enhanced the anticonvulsant properties) of 1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one hydrochloride, CFM-2, a noncompetitive AMPA receptor antagonist, and 3-((+/-)-2-carboxypiperazin-4-yl)-1-phosphonic acid, CPPene, a competitive NMDA receptor antagonist, in DBA/2 mice. In addition, (R,S)-PPG and ACPT-1 administered intracerebroventricularly prolonged the time course of the anticonvulsant properties of CFM-2 (33 micromol/kg, i.p.) and CPPene (3.3 micromol/kg, i.p.) administered intraperitoneally. We conclude that modest reduction of synaptic glutamate release by activation of Group III metabotropic receptors potentiates the anticonvulsant effect of AMPA and NMDA receptor blockade. Copyright 2002 Elsevier Science B.V.

  7. Therapeutic potential of α7 nicotinic receptor agonists to regulate neuroinflammation in neurodegenerative diseases

    Directory of Open Access Journals (Sweden)

    Laura Foucault-Fruchard

    2017-01-01

    Full Text Available Neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's diseases, are all characterized by a component of innate immunity called neuroinflammation. Neuronal loss and neuroinflammation are two phenomena closely linked. Hence, the neuroinflammation is a relevant target for the management of the neurodegenerative diseases given that, to date, there is no treatment to stop neuronal loss. Several studies have investigated the potential effects of activators of alpha 7 nicotinic acetylcholine receptors in animal models of neurodegenerative diseases. These receptors are widely distributed in the central nervous system. After activation, they seem to mediate the cholinergic anti-inflammatory pathway in the brain. This anti-inflammatory pathway, first described in periphery, regulates activation of microglial cells considered as the resident macrophage population of the central nervous system. In this article, we shortly review the agonists of the alpha 7 nicotinic acetylcholine receptors that have been evaluated in vivo and we focused on the selective positive allosteric modulators of these receptors. These compounds represent a key element to enhance receptor activity only in the presence of the endogenous agonist.

  8. Arctigenin functions as a selective agonist of estrogen receptor ? to restrict mTORC1 activation and consequent Th17 differentiation

    OpenAIRE

    Wu, Xin; Tong, Bei; Yang, Yan; Luo, Jinque; Yuan, Xusheng; Wei, Zhifeng; Yue, Mengfan; Xia, Yufeng; Dai, Yue

    2016-01-01

    Arctigenin was previously proven to inhibit Th17 cell differentiation and thereby attenuate colitis in mice by down-regulating the activation of mechanistic target of rapamycin complex 1 (mTORC1). The present study was performed to address its underlying mechanism in view of estrogen receptor (ER). The specific antagonist PHTPP or siRNA of ER? largely diminished the inhibitory effect of arctigenin on the mTORC1 activation in T cell lines and primary CD4+ T cells under Th17-polarization condit...

  9. Quantitative phosphoproteomics dissection of seven-transmembrane receptor signaling using full and biased agonists

    DEFF Research Database (Denmark)

    Christensen, Gitte L; Kelstrup, Christian D; Lyngsø, Christina

    2010-01-01

    (q)-dependent and -independent AT(1)R signaling. This study provides substantial novel insight into angiotensin II signal transduction and is the first study dissecting the differences between a full agonist and a biased agonist from a 7TMR on a systems-wide scale. Importantly, it reveals a previously unappreciated diversity......Seven-transmembrane receptors (7TMRs) signal through the well described heterotrimeric G proteins but can also activate G protein-independent signaling pathways of which the impact and complexity are less understood. The angiotensin II type 1 receptor (AT(1)R) is a prototypical 7TMR...... and quantity of Galpha(q) protein-independent signaling and uncovers novel signaling pathways. We foresee that the amount and diversity of G protein-independent signaling may be more pronounced than previously recognized for other 7TMRs as well. Quantitative mass spectrometry is a promising tool for evaluation...

  10. The liver X receptor agonist T0901317 acts as androgen receptor antagonist in human prostate cancer cells

    International Nuclear Information System (INIS)

    Chuu, Chih-pin; Chen, Rou-Yu; Hiipakka, Richard A.; Kokontis, John M.; Warner, Karen V.; Xiang, Jialing; Liao, Shutsung

    2007-01-01

    T0901317 is a potent non-steroidal synthetic liver X receptor (LXR) agonist. T0901317 blocked androgenic stimulation of the proliferation of androgen-dependent LNCaP 104-S cells and androgenic suppression of the proliferation of androgen-independent LNCaP 104-R2 cells, inhibited the transcriptional activation of an androgen-dependent reporter gene by androgen, and suppressed gene and protein expression of prostate specific antigen (PSA), a target gene of androgen receptor (AR) without affecting gene and protein expression of AR. T0901317 also inhibited binding of a radiolabeled androgen to AR, but inhibition was much weaker compared to the effect of the antiandrogens, bicalutamide and hydroxyflutamide. The LXR agonist T0901317, therefore, acts as an antiandrogen in human prostate cancer cells

  11. Preclinical evaluation of SMM-189, a cannabinoid receptor 2-specific inverse agonist.

    Science.gov (United States)

    Presley, Chaela; Abidi, Ammaar; Suryawanshi, Satyendra; Mustafa, Suni; Meibohm, Bernd; Moore, Bob M

    2015-08-01

    Cannabinoid receptor 2 agonists and inverse agonists are emerging as new therapeutic options for a spectrum of autoimmune-related disease. Of particular interest, is the ability of CB2 ligands to regulate microglia function in neurodegenerative diseases and traumatic brain injury. We have previously reported the receptor affinity of 3',5'-dichloro-2,6-dihydroxy-biphenyl-4-yl)-phenyl-methanone (SMM-189) and the characterization of the beneficial effects of SMM-189 in the mouse model of mild traumatic brain injury. Herein, we report the further characterization of SMM-189 as a potent and selective CB2 inverse agonist, which acts as a noncompetitive inhibitor of CP 55,940. The ability of SMM-189 to regulate microglial activation, in terms of chemokine expression and cell morphology, has been determined. Finally, we have determined that SMM-189 possesses acceptable biopharmaceutical properties indicating that the triaryl class of CB2 inverse agonists are viable compounds for continued preclinical development for the treatment of neurodegenerative disorders and traumatic brain injury.

  12. The 5-HT(1F) receptor agonist lasmiditan as a potential treatment of migraine attacks

    DEFF Research Database (Denmark)

    Tfelt-Hansen, Peer C; Olesen, Jes

    2012-01-01

    Lasmiditan is a novel selective 5-HT(1F) receptor agonist. It is both scientifically and clinically relevant to review whether a 5-HT(1F) receptor agonist is effective in the acute treatment of migraine. Two RCTs in the phase II development of lasmiditan was reviewed. In the intravenous placebo...

  13. Small-molecule agonists for the glucagon-like peptide 1 receptor

    DEFF Research Database (Denmark)

    Knudsen, Lotte Bjerre; Kiel, Dan; Teng, Min

    2007-01-01

    and independent agonists. Potency of GLP-1 was not changed by the allosteric agonists, but affinity of GLP-1 for the receptor was increased. The most potent compound identified stimulates glucose-dependent insulin release from normal mouse islets but, importantly, not from GLP-1 receptor knockout mice. Also...

  14. Click-Chemistry-Mediated Synthesis of Selective Melanocortin Receptor 4 Agonists

    DEFF Research Database (Denmark)

    Palmer, Daniel; Gonçalves, Juliana P.L.; Hansen, Louise V.

    2017-01-01

    The melanocortin receptor 4 (MC4R) subtype of the melanocortin receptor family is a target for therapeutics to ameliorate metabolic dysfunction. Endogenous MC4R agonists possess a critical pharmacophore (HFRW), and cyclization of peptide agonists often enhances potency. Thus, 17 cyclized peptides...

  15. Discovery of a potent and selective free fatty acid receptor 1 agonist with low lipophilicity and high oral bioavailability

    DEFF Research Database (Denmark)

    Christiansen, Elisabeth; Due-Hansen, Maria E; Urban, Christian

    2013-01-01

    The free fatty acid receptor 1 (FFA1, also known as GPR40) mediates enhancement of glucose-stimulated insulin secretion and is emerging as a new target for the treatment of type 2 diabetes. Several FFA1 agonists are known, but the majority of these suffer from high lipophilicity. We have previously...... reported the FFA1 agonist 3 (TUG-424). We here describe the continued structure-activity exploration and optimization of this compound series, leading to the discovery of the more potent agonist 40, a compound with low lipophilicity, excellent in vitro metabolic stability and permeability, complete oral...

  16. Trial Watch: Toll-like receptor agonists in oncological indications.

    Science.gov (United States)

    Aranda, Fernando; Vacchelli, Erika; Obrist, Florine; Eggermont, Alexander; Galon, Jérôme; Sautès-Fridman, Catherine; Cremer, Isabelle; Henrik Ter Meulen, Jan; Zitvogel, Laurence; Kroemer, Guido; Galluzzi, Lorenzo

    2014-01-01

    Toll-like receptors (TLRs) are an evolutionarily conserved group of enzymatically inactive, single membrane-spanning proteins that recognize a wide panel of exogenous and endogenous danger signals. Besides constituting a crucial component of the innate immune response to bacterial and viral pathogens, TLRs appear to play a major role in anticancer immunosurveillance. In line with this notion, several natural and synthetic TLR ligands have been intensively investigated for their ability to boost tumor-targeting immune responses elicited by a variety of immunotherapeutic and chemotherapeutic interventions. Three of these agents are currently approved by the US Food and Drug Administration (FDA) or equivalent regulatory agencies for use in cancer patients: the so-called bacillus Calmette-Guérin, monophosphoryl lipid A, and imiquimod. However, the number of clinical trials testing the therapeutic potential of both FDA-approved and experimental TLR agonists in cancer patients is stably decreasing, suggesting that drug developers and oncologists are refocusing their interest on alternative immunostimulatory agents. Here, we summarize recent findings on the use of TLR agonists in cancer patients and discuss how the clinical evaluation of FDA-approved and experimental TLR ligands has evolved since the publication of our first Trial Watch dealing with this topic.

  17. Discovery of an Oxybenzylglycine Based Peroxisome Proliferator Activated Receptor [alpha] Selective Agonist 2-((3-((2-(4-Chlorophenyl)-5-methyloxazol-4-yl)methoxy)benzyl)(methoxycarbonyl)amino)acetic Acid (BMS-687453)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun; Kennedy, Lawrence J.; Shi, Yan; Tao, Shiwei; Ye, Xiang-Yang; Chen, Stephanie Y.; Wang, Ying; Hernndez, Andrs S.; Wang, Wei; Devasthale, Pratik V.; Chen, Sean; Lai, Zhi; Zhang, Hao; Wu, Shung; Smirk, Rebecca A.; Bolton, Scott A.; Ryono, Denis E.; Zhang, Huiping; Lim, Ngiap-Kie; Chen, Bang-Chi; Locke, Kenneth T.; O’Malley, Kevin M.; Zhang, Litao; Srivastava, Rai Ajit; Miao, Bowman; Meyers, Daniel S.; Monshizadegan, Hossain; Search, Debra; Grimm, Denise; Zhang, Rongan; Harrity, Thomas; Kunselman, Lori K.; Cap, Michael; Kadiyala, Pathanjali; Hosagrahara, Vinayak; Zhang, Lisa; Xu, Carrie; Li, Yi-Xin; Muckelbauer, Jodi K.; Chang, Chiehying; An, Yongmi; Krystek, Stanley R.; Blanar, Michael A.; Zahler, Robert; Mukherjee, Ranjan; Cheng, Peter T.W.; Tino, Joseph A. (BMS)

    2010-04-12

    An 1,3-oxybenzylglycine based compound 2 (BMS-687453) was discovered to be a potent and selective peroxisome proliferator activated receptor (PPAR) {alpha} agonist, with an EC{sub 50} of 10 nM for human PPAR{alpha} and 410-fold selectivity vs human PPAR{gamma} in PPAR-GAL4 transactivation assays. Similar potencies and selectivity were also observed in the full length receptor co-transfection assays. Compound 2 has negligible cross-reactivity against a panel of human nuclear hormone receptors including PPAR{delta}. Compound 2 demonstrated an excellent pharmacological and safety profile in preclinical studies and thus was chosen as a development candidate for the treatment of atherosclerosis and dyslipidemia. The X-ray cocrystal structures of the early lead compound 12 and compound 2 in complex with PPAR{alpha} ligand binding domain (LBD) were determined. The role of the crystal structure of compound 12 with PPAR{alpha} in the development of the SAR that ultimately resulted in the discovery of compound 2 is discussed.

  18. Evaluation of partial beta-adrenoceptor agonist activity.

    Science.gov (United States)

    Lipworth, B J; Grove, A

    1997-01-01

    A partial beta-adrenoceptor (beta-AR) agonist will exhibit opposite agonist and antagonist activity depending on the prevailing degree of adrenergic tone or the presence of a beta-AR agonist with higher intrinsic activity. In vivo partial beta-AR agonist activity will be evident at rest with low endogenous adrenergic tone, as for example with chronotropicity (beta 1/beta 2), inotropicity (beta 1) or peripheral vasodilatation and finger tremor (beta 2). beta-AR blocking drugs which have partial agonist activity may exhibit a better therapeutic profile when used for hypertension because of maintained cardiac output without increased systemic vascular resistance, along with an improved lipid profile. In the presence of raised endogenous adrenergic tone such as exercise or an exogenous full agonist, beta-AR subtype antagonist activity will become evident in terms of effects on exercise induced heart rate (beta 1) and potassium (beta 2) responses. Reduction of exercise heart rate will occur to a lesser degree in the case of a beta-adrenoceptor blocker with partial beta 1-AR agonist activity compared with a beta-adrenoceptor blocker devoid of partial agonist activity. This may result in reduced therapeutic efficacy in the treatment of angina on effort when using beta-AR blocking drugs with partial beta 1-AR agonist activity. Effects on exercise hyperkalaemia are determined by the balance between beta 2-AR partial agonist activity and endogenous adrenergic activity. For predominantly beta 2-AR agonist such as salmeterol and salbutamol, potentiation of exercise hyperkalaemia occurs. For predominantly beta 2-AR antagonists such as carteolol, either potentiation or attenuation of exercise hyperkalaemia occurs at low and high doses respectively. beta 2-AR partial agonist activity may also be expressed as antagonism in the presence of an exogenous full agonist, as for example attenuation of fenoterol induced responses by salmeterol. Studies are required to investigate whether

  19. Radiosynthesis and evaluation of 11C-CIMBI-5 as a 5-HT2A receptor agonist radioligand for PET

    DEFF Research Database (Denmark)

    Ettrup, Anders; Palner, Mikael; Gillings, Nic

    2010-01-01

    PET brain imaging of the serotonin 2A (5-hydroxytryptamine 2A, or 5-HT(2A)) receptor has been widely used in clinical studies, and currently, several well-validated radiolabeled antagonist tracers are used for in vivo imaging of the cerebral 5-HT(2A) receptor. Access to 5-HT(2A) receptor agonist...... PET tracers would, however, enable imaging of the active, high-affinity state of receptors, which may provide a more meaningful assessment of membrane-bound receptors. In this study, we radiolabel the high-affinity 5-HT(2A) receptor agonist 2-(4-iodo-2,5-dimethoxyphenyl)-N-(2-[(11)C-OCH(3......)]methoxybenzyl)ethanamine ((11)C-CIMBI-5) and investigate its potential as a PET tracer....

  20. Transcriptomic and phenotypic profiling in developing zebrafish exposed to thyroid hormone receptor agonists

    Energy Technology Data Exchange (ETDEWEB)

    Haggard, Derik E.; Noyes, Pamela D.; Waters, Katrina M.; Tanguay, Robert L.

    2018-04-01

    There is a need to develop novel, high-throughput screening and prioritization methods to identify chemicals with adverse estrogen, androgen, and thyroid activity to protect human health and the environment and is of interest to the Endocrine Disruptor Screening Program. The current aim is to explore the utility of zebrafish as a testing paradigm to classify endocrine activity using phenotypically anchored transcriptome profiling. Transcriptome analysis was conducted on embryos exposed to 25 estrogen-, androgen-, or thyroid-active chemicals at a concentration that elicited adverse malformations or mortality at 120 hours post-fertilization in 80% of the animals exposed. Analysis of the top 1000 significant differentially expressed transcripts across all treatments identified a unique transcriptional and phenotypic profile for thyroid hormone receptor agonists, which can be used as a biomarker screen for potential thyroid hormone agonists.

  1. A Novel Role of Serotonin Receptor 2B Agonist as an Anti-Melanogenesis Agent

    Directory of Open Access Journals (Sweden)

    Eun Ju Oh

    2016-04-01

    Full Text Available BW723C86, a serotonin receptor 2B agonist, has been investigated as a potential therapeutic for various conditions such as anxiety, hyperphagia and hypertension. However, the functional role of BW723C86 against melanogenesis remains unclear. In this study, we investigate the effect of serotonin receptor 2B (5-HTR2B agonist on melanogenesis and elucidate the mechanism involved. BW723C86 reduced melanin synthesis and intracellular tyrosinase activity in melan-A cells and normal human melanocytes. The expression of melanogenesis-related proteins (tyrosinase, TRP-1 and TRP-2 and microphthalmia-associated transcription factor (MITF in melan-A cells decreased after BW723C86 treatment. The promoter activity of MITF was also reduced by BW723C86 treatment. The reduced level of MITF was associated with inhibition of protein kinase A (PKA and cAMP response element-binding protein (CREB activation by BW723C86 treatment. These results suggest that the serotonin agonist BW723C86 could be a potential therapeutic agent for skin hyperpigmentation disorders.

  2. Agonist-mediated activation of Bombyx mori diapause hormone receptor signals to extracellular signal-regulated kinases 1 and 2 through Gq-PLC-PKC-dependent cascade.

    Science.gov (United States)

    Jiang, Xue; Yang, Jingwen; Shen, Zhangfei; Chen, Yajie; Shi, Liangen; Zhou, Naiming

    2016-08-01

    Diapause is a developmental strategy adopted by insects to survive in challenging environments such as the low temperatures of a winter. This unique process is regulated by diapause hormone (DH), which is a neuropeptide hormone that induces egg diapause in Bombyx mori and is involved in terminating pupal diapause in heliothis moths. An G protein-coupled receptor from the silkworm, B. mori, has been identified as a specific cell surface receptor for DH. However, the detailed information on the DH-DHR system and its mechanism(s) involved in the induction of embryonic diapause remains unknown. Here, we combined functional assays with various specific inhibitors to elucidate the DHR-mediated signaling pathways. Upon activation by DH, B. mori DHR is coupled to the Gq protein, leading to a significant increase of intracellular Ca(2+) and cAMP response element-driven luciferase activity in an UBO-QIC, a specific Gq inhibitor, sensitive manner. B. mori DHR elicited ERK1/2 phosphorylation in a dose- and time-dependent manner in response to DH. This effect was almost completely inhibited by co-incubation with UBO-QIC and was also significantly suppressed by PLC inhibitor U73122, PKC inhibitors Gö6983 and the Ca(2+) chelator EGTA. Moreover, DHR-induced activation of ERK1/2 was significantly attenuated by treatment with the Gβγ specific inhibitors gallein and M119K and the PI3K specific inhibitor Wortmannin, but not by the Src specific inhibitor PP2. Our data also demonstrates that the EGFR-transactivation pathway is not involved in the DHR-mediated ERK1/2 phosphorylation. Future efforts are needed to clarify the role of the ERK1/2 signaling pathway in the DH-mediated induction of B. mori embryonic diapause. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Differential Modulation of GABAA and NMDA Receptors by an α7-nicotinic Acetylcholine Receptor Agonist in Chronic Glaucoma

    Directory of Open Access Journals (Sweden)

    Xujiao Zhou

    2017-12-01

    Full Text Available Presynaptic modulation of γ-aminobutyric acid (GABA release by an alpha7 nicotinic acetylcholine receptor (α7-nAChR agonist promotes retinal ganglion cell (RGC survival and function, as suggested by a previous study on a chronic glaucomatous model from our laboratory. However, the role of excitatory and inhibitory amino acid receptors and their interaction with α7-nAChR in physiological and glaucomatous events remains unknown. In this study, we investigated GABAA and N-methyl-D-aspartate (NMDA receptor activity in control and glaucomatous retinal slices and the regulation of amino acid receptor expression and function by α7-nAChR. Whole-cell patch-clamp recordings from RGCs revealed that the α7-nAChR specific agonist PNU-282987 enhanced the amplitude of currents elicited by GABA and reduced the amplitude of currents elicited by NMDA. The positive modulation of GABAA receptor and the negative modulation of NMDA receptor (NMDAR by PNU-282987-evoked were prevented by pre-administration of the α7-nAChR antagonist methyllycaconitine (MLA. The frequency and the amplitude of glutamate receptor-mediated miniature glutamatergic excitatory postsynaptic currents (mEPSCs were not significantly different between the control and glaucomatous RGCs. Additionally, PNU-282987-treated slices showed no alteration in the frequency or amplitude of mEPSCs relative to control RGCs. Moreover, we showed that expression of the α1 subunit of the GABAA receptor was downregulated and the expression of the NMDAR NR2B subunit was upregulated by intraocular pressure (IOP elevation, and the changes of high IOP were blocked by PNU-282987. In conclusion, retina GABAA and NMDARs are modulated positively and negatively, respectively, by activation of α7-nAChR in in vivo chronic glaucomatous models.

  4. Agonist-induced affinity alterations of a central nervous system. cap alpha. -bungarotoxin receptor

    Energy Technology Data Exchange (ETDEWEB)

    Lukas, R.J.; Bennett, E.L.

    1979-01-01

    The ability of cholinergic agonists to block the specific interaction of ..cap alpha..-bungarotoxin (..cap alpha..-Bgt) with membrane-bound sites derived from rat brain is enhanced when membranes are preincubated with agonist. Thus, pretreatment of ..cap alpha..-Bgt receptors with agonist (but not antagonist) causes transformation of sites to a high-affinity form toward agonist. This change in receptor state occurs with a half-time on the order of minutes, and is fully reversible on dilution of agonist. The results are consistent with the identity of ..cap alpha..-Bgt binding sites as true central nicotinic acetylcholine receptors. Furthermore, this agonist-induced alteration in receptor state may represent an in vitro correlate of physiological desensitization. As determined from the effects of agonist on toxin binding isotherms, and on the rate of toxin binding to specific sites, agonist inhibition of toxin binding to the high-affinity state is non-competitive. This result suggests that there may exist discrete toxin-binding and agonist-binding sites on central toxin receptors.

  5. Endomorphin-2: a biased agonist at the μ-opioid receptor.

    Science.gov (United States)

    Rivero, Guadalupe; Llorente, Javier; McPherson, Jamie; Cooke, Alex; Mundell, Stuart J; McArdle, Craig A; Rosethorne, Elizabeth M; Charlton, Steven J; Krasel, Cornelius; Bailey, Christopher P; Henderson, Graeme; Kelly, Eamonn

    2012-08-01

    Previously we correlated the efficacy for G protein activation with that for arrestin recruitment for a number of agonists at the μ-opioid receptor (MOPr) stably expressed in HEK293 cells. We suggested that the endomorphins (endomorphin-1 and -2) might be biased toward arrestin recruitment. In the present study, we investigated this phenomenon in more detail for endomorphin-2, using endogenous MOPr in rat brain as well as MOPr stably expressed in HEK293 cells. For MOPr in neurons in brainstem locus ceruleus slices, the peptide agonists [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) and endomorphin-2 activated inwardly rectifying K(+) current in a concentration-dependent manner. Analysis of these responses with the operational model of pharmacological agonism confirmed that endomorphin-2 had a much lower operational efficacy for G protein-mediated responses than did DAMGO at native MOPr in mature neurons. However, endomorphin-2 induced faster desensitization of the K(+) current than did DAMGO. In addition, in HEK293 cells stably expressing MOPr, the ability of endomorphin-2 to induce phosphorylation of Ser375 in the COOH terminus of the receptor, to induce association of arrestin with the receptor, and to induce cell surface loss of receptors was much more efficient than would be predicted from its efficacy for G protein-mediated signaling. Together, these results indicate that endomorphin-2 is an arrestin-biased agonist at MOPr and the reason for this is likely to be the ability of endomorphin-2 to induce greater phosphorylation of MOPr than would be expected from its ability to activate MOPr and to induce activation of G proteins.

  6. Liver X Receptor Agonists Inhibit the Phospholipid Regulatory Gene CTP: Phosphoethanolamine Cytidylyltransferase-Pcyt2

    Directory of Open Access Journals (Sweden)

    Lin Zhu

    2008-01-01

    Full Text Available Metabolic pulse-chase experiments demonstrated that 25-hydroxycholesterol (25-OH, the endogenous activator of the liver X receptor (LXR, significantly reduced the biosynthesis of phosphatidylethanolamine via CDP-ethanolamine (Kennedy pathway at the step catalyzed by CTP: phosphoethanolamine cytidylyltransferase (Pcyt2. In the mouse embryonic fibroblasts C3H10T1/2, the LXR synthetic agonist TO901317 lowered Pcyt2 promoter-luciferase activity in a concentration-dependent manner. Furthermore, 25-OH and TO901317 reduced mouse Pcyt2 mRNA and protein levels by 35–60%. The inhibitory effects of oxysterols and TO901317 on the Pcyt2 promoter function, mRNA and protein expression were conserved in the human breast cancer cells MCF-7. These studies identify the Pcyt2 gene as a novel target whereby LXR agonists may indirectly modulate inflammatory responses and atherosclerosis.

  7. Effects of agonist efficacy on desensitization of phosphoinositide hydrolysis mediated by m1 and m3 muscarinic receptors expressed in Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    Hu, J.; Wang, S.Z.; el-Fakahany, E.E.

    1991-01-01

    Muscarinic receptor agonist-induced desensitization of phosphoinositide (PI) hydrolysis and loss of receptors were studied in Chinese hamster ovary (CHO) cells transfected with the m1 and m3 muscarinic receptor genes. Long-term exposure to the full agonist carbamylcholine (CBC) resulted in a time-dependent attenuation of the maximal PI response and a decrease in agonist potency. This desensitization was accompanied by a parallel loss of maximal ligand binding without an alteration of the binding affinity. The time course of both receptor desensitization and down-regulation was similar in m1 and m3 CHO cells. The PI response to the partial agonist McN-A-343 (McN) in m1 cells was more sensitive to desensitization by CBC than the response to the latter agonist, and this desensitization was faster than receptor down-regulation. Desensitization of the PI response to McN was reflected as a decrease in the maximal response without a marked change in potency. McN induced slow desensitization of the PI response to CBC but a much faster desensitization of its own response. Our data provide evidence that although muscarinic agonist-induced desensitization of PI hydrolysis in CHO cells is due mainly to loss of receptors, there are other important factors which play a role in this process, e.g., receptor-effector uncoupling. The relative contribution of these different mechanisms depends on the efficacy of the agonists used for the receptor desensitization and activation steps

  8. The electrophysiological effects of the serotonin 1A receptor agonist buspirone in emotional face processing.

    Science.gov (United States)

    Bernasconi, Fosco; Kometer, Michael; Pokorny, Thomas; Seifritz, Erich; Vollenweider, Franz X

    2015-04-01

    Emotional face processing is critically modulated by the serotonergic system, and serotonin (5-HT) receptor agonists impair emotional face processing. However, the specific contribution of the 5-HT1A receptor remains poorly understood. Here we investigated the spatiotemporal brain mechanisms underpinning the modulation of emotional face processing induced by buspirone, a partial 5-HT1A receptor agonist. In a psychophysical discrimination of emotional faces task, we observed that the discrimination fearful versus neutral faces were reduced, but not happy versus neutral faces. Electrical neuroimaging analyses were applied to visual evoked potentials elicited by emotional face images, after placebo and buspirone administration. Buspirone modulated response strength (i.e., global field power) in the interval 230-248ms after stimulus onset. Distributed source estimation over this time interval revealed that buspirone decreased the neural activity in the right dorsolateral prefrontal cortex that was evoked by fearful faces. These results indicate temporal and valence-specific effects of buspirone on the neuronal correlates of emotional face processing. Furthermore, the reduced neural activity in the dorsolateral prefrontal cortex in response to fearful faces suggests a reduced attention to fearful faces. Collectively, these findings provide new insights into the role of 5-HT1A receptors in emotional face processing and have implications for affective disorders that are characterized by an increased attention to negative stimuli. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  9. Muscarinic receptor agonists stimulate matrix metalloproteinase 1-dependent invasion of human colon cancer cells

    International Nuclear Information System (INIS)

    Raufman, Jean-Pierre; Cheng, Kunrong; Saxena, Neeraj; Chahdi, Ahmed; Belo, Angelica; Khurana, Sandeep; Xie, Guofeng

    2011-01-01

    Highlights: ► Muscarinic receptor agonists stimulated robust human colon cancer cell invasion. ► Anti-matrix metalloproteinase1 antibody pre-treatment blocks cell invasion. ► Bile acids stimulate MMP1 expression, cell migration and MMP1-dependent invasion. -- Abstract: Mammalian matrix metalloproteinases (MMPs) which degrade extracellular matrix facilitate colon cancer cell invasion into the bloodstream and extra-colonic tissues; in particular, MMP1 expression correlates strongly with advanced colon cancer stage, hematogenous metastasis and poor prognosis. Likewise, muscarinic receptor signaling plays an important role in colon cancer; muscarinic receptors are over-expressed in colon cancer compared to normal colon epithelial cells. Muscarinic receptor activation stimulates proliferation, migration and invasion of human colon cancer cells. In mouse intestinal neoplasia models genetic ablation of muscarinic receptors attenuates carcinogenesis. In the present work, we sought to link these observations by showing that MMP1 expression and activation plays a mechanistic role in muscarinic receptor agonist-induced colon cancer cell invasion. We show that acetylcholine, which robustly increases MMP1 expression, stimulates invasion of HT29 and H508 human colon cancer cells into human umbilical vein endothelial cell monolayers – this was abolished by pre-incubation with atropine, a non-selective muscarinic receptor inhibitor, and by pre-incubation with anti-MMP1 neutralizing antibody. Similar results were obtained using a Matrigel chamber assay and deoxycholyltaurine (DCT), an amidated dihydroxy bile acid associated with colon neoplasia in animal models and humans, and previously shown to interact functionally with muscarinic receptors. DCT treatment of human colon cancer cells resulted in time-dependent, 10-fold increased MMP1 expression, and DCT-induced cell invasion was also blocked by pre-treatment with anti-MMP1 antibody. This study contributes to understanding

  10. Muscarinic receptor agonists stimulate matrix metalloproteinase 1-dependent invasion of human colon cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Raufman, Jean-Pierre, E-mail: jraufman@medicine.umaryland.edu [Division of Gastroenterology and Hepatology, University of Maryland School of Medicine, Baltimore, MD (United States); Cheng, Kunrong; Saxena, Neeraj; Chahdi, Ahmed; Belo, Angelica; Khurana, Sandeep; Xie, Guofeng [Division of Gastroenterology and Hepatology, University of Maryland School of Medicine, Baltimore, MD (United States)

    2011-11-18

    Highlights: Black-Right-Pointing-Pointer Muscarinic receptor agonists stimulated robust human colon cancer cell invasion. Black-Right-Pointing-Pointer Anti-matrix metalloproteinase1 antibody pre-treatment blocks cell invasion. Black-Right-Pointing-Pointer Bile acids stimulate MMP1 expression, cell migration and MMP1-dependent invasion. -- Abstract: Mammalian matrix metalloproteinases (MMPs) which degrade extracellular matrix facilitate colon cancer cell invasion into the bloodstream and extra-colonic tissues; in particular, MMP1 expression correlates strongly with advanced colon cancer stage, hematogenous metastasis and poor prognosis. Likewise, muscarinic receptor signaling plays an important role in colon cancer; muscarinic receptors are over-expressed in colon cancer compared to normal colon epithelial cells. Muscarinic receptor activation stimulates proliferation, migration and invasion of human colon cancer cells. In mouse intestinal neoplasia models genetic ablation of muscarinic receptors attenuates carcinogenesis. In the present work, we sought to link these observations by showing that MMP1 expression and activation plays a mechanistic role in muscarinic receptor agonist-induced colon cancer cell invasion. We show that acetylcholine, which robustly increases MMP1 expression, stimulates invasion of HT29 and H508 human colon cancer cells into human umbilical vein endothelial cell monolayers - this was abolished by pre-incubation with atropine, a non-selective muscarinic receptor inhibitor, and by pre-incubation with anti-MMP1 neutralizing antibody. Similar results were obtained using a Matrigel chamber assay and deoxycholyltaurine (DCT), an amidated dihydroxy bile acid associated with colon neoplasia in animal models and humans, and previously shown to interact functionally with muscarinic receptors. DCT treatment of human colon cancer cells resulted in time-dependent, 10-fold increased MMP1 expression, and DCT-induced cell invasion was also blocked by pre

  11. The selective alpha7 nicotinic acetylcholine receptor agonist PNU-282987 [N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide hydrochloride] enhances GABAergic synaptic activity in brain slices and restores auditory gating deficits in anesthetized rats.

    Science.gov (United States)

    Hajós, M; Hurst, R S; Hoffmann, W E; Krause, M; Wall, T M; Higdon, N R; Groppi, V E

    2005-03-01

    Schizophrenic patients are thought to have an impaired ability to process sensory information. This deficit leads to disrupted auditory gating measured electrophysiologically as a reduced suppression of the second of paired auditoryevoked responses (P50) and is proposed to be associated with decreased function and/or expression of the homomeric alpha7 nicotinic acetylcholine receptor (nAChR). Here, we provide evidence that N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide hydrochloride (PNU-282987), a novel selective agonist of the alpha7 nAChR, evoked whole-cell currents from cultured rat hippocampal neurons that were sensitive to the selective alpha7 nAChR antagonist methyllycaconitine (MLA) and enhanced GABAergic synaptic activity when applied to hippocampal slices. Amphetamine-induced sensory gating deficit, determined by auditory-evoked potentials in hippocampal CA3 region, was restored by systemic administration of PNU-282987 in chloral hydrate-anesthetized rats. Auditory gating of rat reticular thalamic neurons was also disrupted by amphetamine; however, PNU-282987 normalized gating deficit only in a subset of tested neurons (6 of 11). Furthermore, PNU-282987 improved the inherent hippocampal gating deficit occurring in a subpopulation of anesthetized rats, and enhanced amphetamine-induced hippocampal oscillation. We propose that the alpha7 nAChR agonist PNU-282987, via modulating/enhancing hippocampal GABAergic neurotransmission, improves auditory gating and enhances hippocampal oscillatory activity. These results provide further support for the concept that drugs that selectively activate alpha7 nAChRs may offer a novel, potential pharmacotherapy in treatment of schizophrenia.

  12. Revealing a steroid receptor ligand as a unique PPAR[gamma] agonist

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shengchen; Han, Ying; Shi, Yuzhe; Rong, Hui; Zheng, Songyang; Jin, Shikan; Lin, Shu-Yong; Lin, Sheng-Cai; Li, Yong (Pitt); (Xiamen)

    2012-06-28

    Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) regulates metabolic homeostasis and is a molecular target for anti-diabetic drugs. We report here the identification of a steroid receptor ligand, RU-486, as an unexpected PPAR{gamma} agonist, thereby uncovering a novel signaling route for this steroid drug. Similar to rosiglitazone, RU-486 modulates the expression of key PPAR{gamma} target genes and promotes adipocyte differentiation, but with a lower adipogenic activity. Structural and functional studies of receptor-ligand interactions reveal the molecular basis for a unique binding mode for RU-486 in the PPAR{gamma} ligand-binding pocket with distinctive properties and epitopes, providing the molecular mechanisms for the discrimination of RU-486 from thiazolidinediones (TZDs) drugs. Our findings together indicate that steroid compounds may represent an alternative approach for designing non-TZD PPAR{gamma} ligands in the treatment of insulin resistance.

  13. Phosphodiesterase inhibitor KMUP-3 displays cardioprotection via protein kinase G and increases cardiac output via G-protein-coupled receptor agonist activity and Ca2+ sensitization

    Directory of Open Access Journals (Sweden)

    Chung-Pin Liu

    2016-02-01

    -kl pyrrolo(3,4-i(1,6benzodiazocine-10-carboxylic acid, methyl ester] (3μM reversed KMUP-3 (1–100μM-induced Ca2+-entry blockade. GPCR agonist activity of KMUP-3 appeared opposed to KMUP-1, and increased cardiac output via Ca2+ sensitization, and displayed cardioprotection via cyclic GMP/PKG-mediated myocardial preconditioning in animal studies.

  14. Working memory span capacity improved by a D2 but not D1 receptor family agonist.

    Science.gov (United States)

    Tarantino, Isadore S; Sharp, Richard F; Geyer, Mark A; Meves, Jessica M; Young, Jared W

    2011-06-01

    Patients with schizophrenia exhibit poor working memory (WM). Although several subcomponents of WM can be measured, evidence suggests the primary subcomponent affected in schizophrenia is span capacity (WMC). Indeed, the NIMH-funded MATRICS initiative recommended assaying the WMC when assessing the efficacy of a putative therapeutic for FDA approval. Although dopamine D1 receptor agonists improve delay-dependent memory in animals, evidence for improvements in WMC due to dopamine D1 receptor activation is limited. In contrast, the dopamine D2-family agonist bromocriptine improves WMC in humans. The radial arm maze (RAM) can be used to assess WMC, although complications due to ceiling effects or strategy confounds have limited its use. We describe a 12-arm RAM protocol designed to assess whether the dopamine D1-family agonist SKF 38393 (0, 1, 3, and 10 mg/kg) or bromocriptine (0, 1, 3, and 10 mg/kg) could improve WMC in C57BL/6N mice (n=12) in cross-over designs. WMC increased and strategy usage decreased with training. The dopamine D1 agonist SKF 38393 had no effect on WMC or long-term memory. Bromocriptine decreased WMC errors, without affecting long-term memory, consistent with human studies. These data confirm that WMC can be measured in mice and reveal drug effects that are consistent with reported effects in humans. Future research is warranted to identify the subtype of the D2-family of receptors responsible for the observed improvement in WMC. Finally, this RAM procedure may prove useful in developing animal models of deficient WMC to further assess putative treatments for the cognitive deficits in schizophrenia. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Agonist-induced internalisation of the glucagon-like peptide-1 receptor is mediated by the Gαq pathway.

    Science.gov (United States)

    Thompson, Aiysha; Kanamarlapudi, Venkateswarlu

    2015-01-01

    The glucagon-like peptide-1 receptor (GLP-1R) is a G-protein-coupled receptor (GPCR) and an important target in the treatment of type 2 diabetes mellitus (T2DM). Upon stimulation with agonist, the GLP-1R signals through both Gαs and Gαq coupled pathways to stimulate insulin secretion. The agonist-induced GLP-1R internalisation has recently been shown to be important for insulin secretion. However, the molecular mechanisms underlying GLP-1R internalisation remain unknown. The aim of this study was to determine the role of GLP-1R downstream signalling pathways in its internalisation. Agonist-induced human GLP-1R (hGLP-1R) internalisation and activity were examined using a number of techniques including immunoblotting, ELISA, immunofluorescence and luciferase assays to determine cAMP production, intracellular Ca(2+) accumulation and ERK phosphorylation. Agonist-induced hGLP-1R internalisation is dependent on caveolin-1 and dynamin. Inhibition of the Gαq pathway but not the Gαs pathway affected hGLP-1R internalisation. Consistent with this, hGLP-1R mutant T149M and small-molecule agonists (compound 2 and compound B), which activate only the Gαs pathway, failed to induce internalisation of the receptor. Chemical inhibitors of the Gαq pathway, PKC and ERK phosphorylation significantly reduced agonist-induced hGLP-1R internalisation. These inhibitors also suppressed agonist-induced ERK1/2 phosphorylation demonstrating that the phosphorylated ERK acts downstream of the Gαq pathway in the hGLP-1R internalisation. In summary, agonist-induced hGLP-1R internalisation is mediated by the Gαq pathway. The internalised hGLP-1R stimulates insulin secretion from pancreatic β-cells, indicating the importance of GLP-1 internalisation for insulin secretion. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Melanocortin Tetrapeptide Ac-His-DPhe-Arg-Trp-NH2 Modified at the Para Position of the Benzyl Side Chain (DPhe): Importance for Mouse Melanocortin-3 Receptor Agonist versus Antagonist Activity

    OpenAIRE

    Proneth, Bettina; Pogozheva, Irina D.; Portillo, Federico P.; Mosberg, Henry I.; Haskell-Luevano, Carrie

    2008-01-01

    The melanocortin-3 and -4 receptors (MC3R, MC4R) have been implicated in energy homeostasis and obesity. Whereas the physiological role of the MC4R is extensively studied, little is known about the MC3R. One caveat is the limited availability of ligands that are selective for the MC3R. Previous studies identified Ac-His-DPhe(p-I)-Arg-Trp-NH2, which possessed partial agonist/antagonist pharmacology at the mMC3R while retaining full nanomolar agonist pharmacology at the mMC4R. These data allowe...

  17. The selective estrogen receptor alpha agonist Org 37663 induces estrogenic effects but lacks antirheumatic activity: a phase IIa trial investigating efficacy and safety of Org 37663 in postmenopausal female rheumatoid arthritis patients receiving stable background methotrexate or sulfasalazine.

    Science.gov (United States)

    van Vollenhoven, Ronald F; Houbiers, Jos G A; Buttgereit, Frank; In 't Hout, Joanna; Boers, Maarten; Leij, Susanne; Kvien, Tore K; Dijkmans, Ben A C; Szczepański, Leszek; Szombati, Istvan; Sierakowski, Stanislaw; Miltenburg, André M M

    2010-02-01

    Multiple lines of evidence suggest that sex hormones may play a role in the pathogenesis or clinical expression of rheumatoid arthritis (RA). Studies on the effects of exogenous estrogens in RA patients have yielded contradictory results. We undertook this study to determine the effects of the selective estrogen receptor alpha (ERalpha) agonist Org 37663 in patients with RA, in terms of both its estrogenic effects and its ability to ameliorate disease activity. A 10-week, multicenter, randomized, double-blind, placebo-controlled, parallel group, dose-finding, proof-of-concept trial was initiated to obtain data on the efficacy and safety of Org 37663 in postmenopausal female patients with RA who were receiving background treatment with either methotrexate or sulfasalazine. Patients were randomized to receive placebo or Org 37663 at doses of 4 mg/day, 15 mg/day, or 50 mg/week. The primary efficacy variable was the Disease Activity Score in 28 joints (DAS28). Org 37663 induced a clear biologic, estrogenic response in several organ systems, including a dose-related increase in levels of sex hormone binding globulin. However, the DAS28 decreased similarly for all treatment groups including placebo, indicating lack of clinical efficacy of Org 37663 in this trial. The observed lack of clinical benefit in RA patients treated with an ERalpha agonist, in association with a clear biologic response to the study drug, provides evidence that a biologically relevant ERalpha-mediated estrogenic effect is not associated with a clinically relevant effect on RA symptoms and signs.

  18. Ghrelin receptor (GHS-R1A) agonists show potential as interventive agents during aging.

    Science.gov (United States)

    Smith, Roy G; Sun, Yuxiang; Jiang, Hong; Albarran-Zeckler, Rosie; Timchenko, Nikolai

    2007-11-01

    Administration of an orally active agonist (MK-0677) of the growth hormone secretagogue receptor (GHS-R1a) to elderly subjects restored the amplitude of endogenous episodic growth hormone (GH) release to that of young adults. Functional benefits include increased lean mass and bone density and modest improvements in strength. In old mice, a similar agonist partially restored function to the thymus and reduced tumor cell growth and metastasis. Treatment of old mice with the endogenous GHS-R1a agonist ghrelin restored a young liver phenotype. The mechanism involves inhibition of cyclin D3:cdk4/cdk6 activity and increased protein phosphatase-2A (PP2A) activity in liver nuclei, which stabilizes the dephosphorylated form of the transcription factor C/EBPalpha preventing the age-dependent formation of the C/EBPalpha-Rb-E2F4-Brm nuclear complex. By inhibiting formation of this complex, repression of E2F target genes is de-repressed and C/EBPalpha regulated expression of Pepck, a regulator of gluconeogenesis, is normalized, thereby restoring a young liver phenotype. In the brain, aging is associated with decline in dopamine function. We investigated the potential neuromodulatory role of GHS-R1a on dopamine action. Neurons were identified in the hippocampus, cortex, substantia nigra, and ventral tegmental areas that coexpressed GHS-R1a and dopamine receptor subtype-1 (D1R). Cell culture studies showed that, in the presence of ghrelin and dopamine, GHS-R and D1R form heterodimers, which modified G-protein signal transduction resulting in amplification of dopamine signaling. We speculate that aging is associated with deficient endogenous ghrelin signaling that can be rescued by intervention with GHS-R1a agonists to improve quality of life and maintain independence.

  19. Agonist/antagonist interactions with cloned human 5-HT(1A) receptors: Variations in intrinsic activity studied in transfected HeLa cells

    NARCIS (Netherlands)

    Boddeke, H.W.G.M.; Fargin, A.; Raymond, J.R.; Schoeffter, P.; Hoyer, D.

    1992-01-01

    The characteristics of 5-HT(1A)-recognition sites and receptor-mediated release of intracellular calcium were established in two transfected HeLa cell lines (HA 6 and HA 7) expressing different levels of human 5-HT(1A) receptors (about 3000 and 500 fmol/mg protein, Fargin et al. 1989; 1991; Raymond

  20. (+)Lysergic acid diethylamide, but not its nonhallucinogenic congeners, is a potent serotonin 5HT1C receptor agonist

    International Nuclear Information System (INIS)

    Burris, K.D.; Breeding, M.; Sanders-Bush, E.

    1991-01-01

    Activation of central serotonin 5HT2 receptors is believed to be the primary mechanism whereby lysergic acid diethylamide (LSD) and other hallucinogens induce psychoactive effects. This hypothesis is based on extensive radioligand binding and electrophysiological and behavioral studies in laboratory animals. However, the pharmacological profiles of 5HT2 and 5HT1C receptors are similar, making it difficult to distinguish between effects due to activation of one or the other receptor. For this reason, it was of interest to investigate the interaction of LSD with 5HT1C receptors. Agonist-stimulated phosphoinositide hydrolysis in rat choroid plexus was used as a direct measure of 5HT1C receptor activation. (+)LSD potently stimulated phosphoinositide hydrolysis in intact choroid plexus and in cultures of choroid plexus epithelial cells, with EC50 values of 9 and 26 nM, respectively. The effect of (+)LSD in both systems was blocked by 5HT receptor antagonists with an order of activity consistent with interaction at 5HT1C receptors. Neither (+)-2-bromo-LSD nor lisuride, two nonhallucinogenic congeners of LSD, were able to stimulate 5HT1C receptors in cultured cells or intact choroid plexus. In contrast, lisuride, like (+)LSD, is a partial agonist at 5HT2 receptors in cerebral cortex slices and in NIH 3T3 cells transfected with 5HT2 receptor cDNA. The present finding that (+)LSD, but not its nonhallucinogenic congeners, is a 5HT1C receptor agonist suggests a possible role for these receptors in mediating the psychoactive effects of LSD

  1. Cold suppresses agonist-induced activation of TRPV1.

    Science.gov (United States)

    Chung, M-K; Wang, S

    2011-09-01

    Cold therapy is frequently used to reduce pain and edema following acute injury or surgery such as tooth extraction. However, the neurobiological mechanisms of cold therapy are not completely understood. Transient receptor potential vanilloid 1 (TRPV1) is a capsaicin- and heat-gated nociceptive ion channel implicated in thermosensation and pathological pain under conditions of inflammation or injury. Although capsaicin-induced nociception, neuropeptide release, and ionic currents are suppressed by cold, it is not known if cold suppresses agonist-induced activation of recombinant TRPV1. We demonstrate that cold strongly suppressed the activation of recombinant TRPV1 by multiple agonists and capsaicin-evoked currents in trigeminal ganglia neurons under normal and phosphorylated conditions. Cold-induced suppression was partially impaired in a TRPV1 mutant that lacked heat-mediated activation and potentiation. These results suggest that cold-induced suppression of TRPV1 may share a common molecular basis with heat-induced potentiation, and that allosteric inhibition may contribute, in part, to the cold-induced suppression. We also show that combination of cold and a specific antagonist of TRPV1 can produce an additive suppression. Our results provide a mechanistic basis for cold therapy and may enhance anti-nociceptive approaches that target TRPV1 for managing pain under inflammation and tissue injury, including that from tooth extraction.

  2. Diindolylmethane Derivatives: Potent Agonists of the Immunostimulatory Orphan G Protein-Coupled Receptor GPR84.

    Science.gov (United States)

    Pillaiyar, Thanigaimalai; Köse, Meryem; Sylvester, Katharina; Weighardt, Heike; Thimm, Dominik; Borges, Gleice; Förster, Irmgard; von Kügelgen, Ivar; Müller, Christa E

    2017-05-11

    The G i protein-coupled receptor GPR84, which is activated by (hydroxy)fatty acids, is highly expressed on immune cells. Recently, 3,3'-diindolylmethane was identified as a heterocyclic, nonlipid-like GPR84 agonist. We synthesized a broad range of diindolylmethane derivatives by condensation of indoles with formaldehyde in water under microwave irradiation. The products were evaluated at the human GPR84 in cAMP and β-arrestin assays. Structure-activity relationships (SARs) were steep. 3,3'-Diindolylmethanes bearing small lipophilic residues at the 5- and/or 7-position of the indole rings displayed the highest activity in cAMP assays, the most potent agonists being di(5-fluoro-1H-indole-3-yl)methane (38, PSB-15160, EC 50 80.0 nM) and di(5,7-difluoro-1H-indole-3-yl)methane (57, PSB-16671, EC 50 41.3 nM). In β-arrestin assays, SARs were different, indicating biased agonism. The new compounds were selective versus related fatty acid receptors and the arylhydrocarbon receptor. Selected compounds were further investigated and found to display an ago-allosteric mechanism of action and increased stability in comparison to the lead structure.

  3. Molecular and Therapeutic Characterization of Anti-ectodysplasin A Receptor (EDAR) Agonist Monoclonal Antibodies*

    Science.gov (United States)

    Kowalczyk, Christine; Dunkel, Nathalie; Willen, Laure; Casal, Margret L.; Mauldin, Elizabeth A.; Gaide, Olivier; Tardivel, Aubry; Badic, Giovanna; Etter, Anne-Lise; Favre, Manuel; Jefferson, Douglas M.; Headon, Denis J.; Demotz, Stéphane; Schneider, Pascal

    2011-01-01

    The TNF family ligand ectodysplasin A (EDA) and its receptor EDAR are required for proper development of skin appendages such as hair, teeth, and eccrine sweat glands. Loss of function mutations in the Eda gene cause X-linked hypohidrotic ectodermal dysplasia (XLHED), a condition that can be ameliorated in mice and dogs by timely administration of recombinant EDA. In this study, several agonist anti-EDAR monoclonal antibodies were generated that cross-react with the extracellular domains of human, dog, rat, mouse, and chicken EDAR. Their half-life in adult mice was about 11 days. They induced tail hair and sweat gland formation when administered to newborn EDA-deficient Tabby mice, with an EC50 of 0.1 to 0.7 mg/kg. Divalency was necessary and sufficient for this therapeutic activity. Only some antibodies were also agonists in an in vitro surrogate activity assay based on the activation of the apoptotic Fas pathway. Activity in this assay correlated with small dissociation constants. When administered in utero in mice or at birth in dogs, agonist antibodies reverted several ectodermal dysplasia features, including tooth morphology. These antibodies are therefore predicted to efficiently trigger EDAR signaling in many vertebrate species and will be particularly suited for long term treatments. PMID:21730053

  4. Structural Probing and Molecular Modeling of the A₃ Adenosine Receptor: A Focus on Agonist Binding.

    Science.gov (United States)

    Ciancetta, Antonella; Jacobson, Kenneth A

    2017-03-11

    Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR) subtypes, termed A₁, A 2A , A 2B and A₃, which belong to the G protein-coupled receptor (GPCR) superfamily. The human A₃AR (hA₃AR) subtype is implicated in several cytoprotective functions. Therefore, hA₃AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure-activity relationships (SARs) of newly emerged A₃AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM) data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A₃AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates.

  5. Structural Probing and Molecular Modeling of the A3 Adenosine Receptor: A Focus on Agonist Binding

    Science.gov (United States)

    Ciancetta, Antonella; Jacobson, Kenneth A.

    2017-01-01

    Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR) subtypes, termed A1, A2A, A2B and A3, which belong to the G protein-coupled receptor (GPCR) superfamily. The human A3AR (hA3AR) subtype is implicated in several cytoprotective functions. Therefore, hA3AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure-activity relationships (SARs) of newly emerged A3AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM) data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A3AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates. PMID:28287473

  6. Structural Probing and Molecular Modeling of the A3 Adenosine Receptor: A Focus on Agonist Binding

    Directory of Open Access Journals (Sweden)

    Antonella Ciancetta

    2017-03-01

    Full Text Available Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR subtypes, termed A1, A2A, A2B and A3, which belong to the G protein-coupled receptor (GPCR superfamily. The human A3AR (hA3AR subtype is implicated in several cytoprotective functions. Therefore, hA3AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure–activity relationships (SARs of newly emerged A3AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A3AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates.

  7. Misoprostol, an anti-ulcer agent and PGE2 receptor agonist, protects against cerebral ischemia.

    Science.gov (United States)

    Li, Jun; Liang, Xibin; Wang, Qian; Breyer, Richard M; McCullough, Louise; Andreasson, Katrin

    2008-06-20

    Induction of COX-2 activity in cerebral ischemia results in increased neuronal injury and infarct size. Recent studies investigating neurotoxic mechanisms of COX-2 demonstrate both toxic and paradoxically protective effects of downstream prostaglandin receptor signaling pathways. We tested whether misoprostol, a PGE(2) receptor agonist that is utilized clinically as an anti-ulcer agent and signals through the protective PGE(2) EP2, EP3, and EP4 receptors, would reduce brain injury in the murine middle cerebral artery occlusion-reperfusion (MCAO-RP) model. Administration of misoprostol, at the time of MCAO or 2h after MCAO, resulted in significant rescue of infarct volume at 24 and 72h. Immunocytochemistry demonstrated dynamic regulation of the EP2 and EP4 receptors during reperfusion in neurons and endothelial cells of cerebral cortex and striatum, with limited expression of EP3 receptor. EP3-/- mice had no significant changes in infarct volume compared to control littermates. Moreover, administration of misoprostol to EP3+/+ and EP3-/- mice showed similar levels of infarct rescue, indicating that misoprostol protection was not mediated through the EP3 receptor. Taken together, these findings suggest a novel function for misoprostol as a protective agent in cerebral ischemia acting via the PGE(2) EP2 and/or EP4 receptors.

  8. Trialkyltin rexinoid-X receptor agonists selectively potentiate thyroid hormone induced programs of xenopus laevis metamorphosis

    NARCIS (Netherlands)

    Mengeling, Brenda J.; Murk, Albertinka J.; Furlow, J.D.

    2016-01-01

    The trialkyltins tributyltin (TBT) and triphenyltin (TPT) can function as rexinoid-X receptor (RXR) agonists. We recently showed that RXR agonists can alter thyroid hormone (TH) signaling in a mammalian pituitary TH-responsive reporter cell line, GH3.TRE-Luc. The prevalence of TBT and TPT in the

  9. Efficacy and Safety of GLP-1 Receptor Agonists for Type 2 Diabetes Mellitus Treatment: Systematic Review

    Directory of Open Access Journals (Sweden)

    Ana Paula Martins

    2016-04-01

    Full Text Available Introduction: Glucagon-like peptide analogues are a new class of drugs used in the treatment of type 2 diabetes mellitus that mimic the endogenous hormone glucagon-like peptide 1. Glucagon-like peptide 1 regulates glucose levels by stimulating glucose-dependent insulin secretion, suppressing glucagon secretion, delayed gastric emptying and promoting satiety. The individualized treatment of type 2 diabetes mellitus, using various glucagon--like peptide receptor agonists, has recently been described and the interest related to these drugs continues to grow. Objectives: To review the efficacy and safety of glucagon-like peptide 1 agonists in patients with inadequately controlled type 2 diabetes mellitus on metformin alone, highlighting their added value in therapeutic use comparatively to second line oral therapies used in type 2 diabetes mellitus. Methods: Studies were obtained from electronic searches of The Cochrane Library and PubMed. Randomized controlled trials were selected if they were at least 8 weeks in duration; compared a glucagon-like peptide 1 analogue with an oral anti-diabetic agent in patients experiencing inadequate glycemic control with metformin monotherapy; and reported hemoglobin A1c data in non-pregnant adults with type 2 diabetes mellitus. Results: Of 72 potentially relevant articles identified, 23 were retrieved for detailed evaluation and 10 met the inclusion criteria. The majority of glucagon-like peptide 1 agonists showed equivalent or superior efficacy than most active comparators for reducing hemoglobin A1c, with a greater proportion of patients achieving hemoglobin A1c <7%. Glucagon-like peptide 1 agonists also showed extra-glycemic effects such as weight loss and the reduction of important cardiovascular parameters. Side effects included gastrointestinal complications, mainly nausea, vomiting and diarrhea. The incidence of hypoglycemia was less common for this class of agents. Conclusion: Glucagon-like peptide 1

  10. Picosecond dynamics of the glutamate receptor in response to agonist-induced vibrational excitation.

    Science.gov (United States)

    Kubo, Minoru; Shiomitsu, Eiji; Odai, Kei; Sugimoto, Tohru; Suzuki, Hideo; Ito, Etsuro

    2004-02-01

    Conformational changes of proteins are dominated by the excitation and relaxation processes of their vibrational states. To elucidate the mechanism of receptor activation, the conformation dynamics of receptors must be analyzed in response to agonist-induced vibrational excitation. In this study, we chose the bending vibrational mode of the guanidinium group of Arg485 of the glutamate receptor subunit GluR2 based on our previous studies, and we investigated picosecond dynamics of the glutamate receptor caused by the vibrational excitation of Arg485 via molecular dynamics simulations. The vibrational excitation energy in Arg485 in the ligand-binding site initially flowed into Lys730, and then into the J-helix at the subunit interface of the ligand-binding domain. Consequently, the atomic displacement in the subunit interface around an intersubunit hydrogen bond was evoked in about 3 ps. This atomic displacement may perturb the subunit packing of the receptor, triggering receptor activation. Copyright 2003 Wiley-Liss, Inc.

  11. Non-coplanar polychlorinated biphenyls (PCBs) are direct agonists for the human pregnane-X receptor and constitutive androstane receptor, and activate target gene expression in a tissue-specific manner

    International Nuclear Information System (INIS)

    Al-Salman, Fadheela; Plant, Nick

    2012-01-01

    The polychlorinated biphenyl group possesses high environmental persistence, leading to bioaccumulation and a number of adverse effects in mammals. Whilst coplanar PCBs elicit their toxic effects through agonism of the aryl hydrocarbon receptor; however, non-coplanar PCBs are not ligands for AhR, but may be ligands for members of the nuclear receptor family of proteins. To better understand the biological actions of non-coplanar PCBs, we have undertaken a systematic analysis of their ability to activate PXR and CAR-mediated effects. Cells were exposed to a range of non-coplanar PCBs (99, 138, 153, 180 and 194), or the coplanar PCB77: Direct activation of PXR and CAR was measured using a mammalian receptor activation assay in human liver cells, with rifampicin and CITCO used as positive controls ligands for PXR and CAR, respectively; activation of target gene expression was examined using reporter gene plasmids for CYP3A4 and MDR1 transfected into liver, intestine and lung cell lines. Several of the non-coplanar PCBs directly activated PXR and CAR, whilst the coplanar PCB77 did not. Non-coplanar PCBs were also able to activate PXR/CAR target gene expression in a substitution- and tissue-specific manner. Non-coplanar PCBs act as direct activators for the nuclear receptors PXR and CAR, and are able to elicit transcriptional activation of target genes in a substitution- and tissue-dependent manner. Chronic activation of PXR/CAR is linked to adverse effects and must be included in any risk assessment of PCBs. -- Highlights: ► Several Non-coplanar PCBs are able to directly activate both PXR and CAR in vitro. ► PCB153 is the most potent direct activator of PXR and CAR nuclear receptors. ► Non-coplanar PCB activation of CYP3A4/MDR1 reporter genes is structure-dependent. ► Non-coplanar PCB activate CYP3A4/MDR1 reporter genes in a tissue-dependent. ► PCB153 is the most potent activator of PXR/CAR target gene in all tissues.

  12. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

    Science.gov (United States)

    Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-05-03

    Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

  13. The alpha7 nicotinic receptor agonist SSR180711 increases activity regulated cytoskeleton protein (Arc) gene expression in the prefrontal cortex of the rat

    DEFF Research Database (Denmark)

    Kristensen, Søren E; Thomsen, Morten S; Hansen, Henrik H

    2007-01-01

    Nicotinic alpha7 acetylcholine receptors (alpha7 nAChR) have been shown to enhance attentional function and aspects of memory function in experimental models and in man. The protein Arc encoded by the effector immediate early gene arc or arg3.1 has been shown to be strongly implicated in long...

  14. Selective orthosteric free fatty acid receptor 2 (FFA2) agonists: identification of the structural and chemical requirements for selective activation of FFA2 versus FFA3

    DEFF Research Database (Denmark)

    Schmidt, Johannes; Smith, Nicola J; Christiansen, Elisabeth

    2011-01-01

    given its size. Propionate, however, does not discriminate between FFA2 and the closely related receptor FFA3 (GPR41). To identify FFA2 selective ligands and understand the molecular basis for FFA2 selectivity, a targeted library of small carboxylic acids (SCAs) was examined using holistic, label...

  15. Structural Determinants for the Binding of Morphinan Agonists to the μ-Opioid Receptor.

    Directory of Open Access Journals (Sweden)

    Xiaojing Cong

    Full Text Available Atomistic descriptions of the μ-opioid receptor (μOR noncovalently binding with two of its prototypical morphinan agonists, morphine (MOP and hydromorphone (HMP, are investigated using molecular dynamics (MD simulations. Subtle differences between the binding modes and hydration properties of MOP and HMP emerge from the calculations. Alchemical free energy perturbation calculations show qualitative agreement with in vitro experiments performed in this work: indeed, the binding free energy difference between MOP and HMP computed by forward and backward alchemical transformation is 1.2±1.1 and 0.8±0.8 kcal/mol, respectively, to be compared with 0.4±0.3 kcal/mol from experiment. Comparison with an MD simulation of μOR covalently bound with the antagonist β-funaltrexamine hints to agonist-induced conformational changes associated with an early event of the receptor's activation: a shift of the transmembrane helix 6 relative to the transmembrane helix 3 and a consequent loss of the key R165-T279 interhelical hydrogen bond. This finding is consistent with a previous proposal suggesting that the R165-T279 hydrogen bond between these two helices indicates an inactive receptor conformation.

  16. Design of Glucagon-Like Peptide-1 Receptor Agonist for Diabetes Mellitus from Traditional Chinese Medicine

    Directory of Open Access Journals (Sweden)

    Hsin-Chieh Tang

    2014-01-01

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a promising target for diabetes mellitus (DM therapy and reduces the occurrence of diabetes due to obesity. However, GLP-1 will be hydrolyzed soon by the enzyme dipeptidyl peptidase-4 (DPP-4. We tried to design small molecular drugs for GLP-1 receptor agonist from the world's largest traditional Chinese medicine (TCM Database@Taiwan. According to docking results of virtual screening, we selected 2 TCM compounds, wenyujinoside and 28-deglucosylchikusetsusaponin IV, for further molecular dynamics (MD simulation. GLP-1 was assigned as the control compound. Based on the results of root mean square deviation (RMSD, solvent accessible surface (SAS, mean square deviation (MSD, Gyrate, total energy, root mean square fluctuation (RMSF, matrices of smallest distance of residues, database of secondary structure assignment (DSSP, cluster analysis, and distance of H-bond, we concluded that all the 3 compounds could bind and activate GLP-1 receptor by computational simulation. Wenyujinoside and 28-deglucosylchikusetsusaponin IV were the TCM compounds that could be GLP-1 receptor agonists.

  17. In vivo brain dopaminergic receptor site mapping using 75Se-labeled pergolide analogs: the effects of various dopamine receptor agonists and antagonists

    International Nuclear Information System (INIS)

    Weaver, A.

    1986-01-01

    Perogolide mesylate is a new synthetic ergoline derivative which is reported to possess agonistic activity at central dopamine receptor sites in the brain. The authors have synthesized a [ 75 Se]-radiolabeled pergolide mesylate derivative, [ 75 Se]-pergolide tartrate, which, after i.v. administration to mature male rats, showed a time course differentiation in the uptake of this radiolabeled compound in isolated peripheral and central (brain) tissues that are known to be rich in dopamine receptor sites. Further studies were conducted in which the animals were preexposed to the dopamine receptor agonist SKF-38393, as well as the dopamine receptor antagonists (+)-butaclamol, (-)-butaclamol, (+/-)-butaclamol and (-)-chloroethylnorapomorphine, to substantiate the specific peripheral and central localization patterns of [ 75 Se]-pergolide tartrate. Further investigations were also conducted in which the animals received an i.v. administration of N-isopropyl-l-123-p-iodoamphetamine ([ 123 I]-iodoamphetamine). However, [ 123 I]-iodoamphetamine did not demonstrate a specific affinity for any type of receptor site in the brain. These investigations further substantiated the fact that [ 75 Se]-pergolide tartrate does cross the blood-brain barrier is quickly localized at specific dopamine receptor sites in the intact rat brain and that this localization pattern can be affected by preexposure to different dopamine receptor agonists and antagonists. Therefore, these investigations provided further evidence that [ 75 Se]-pergolide tartrate and other radiolabeled ergoline analogs might be useful as brain dopamine receptor localization radiopharmaceuticals

  18. Optimisation of in silico derived 2-aminobenzimidazole hits as unprecedented selective kappa opioid receptor agonists

    DEFF Research Database (Denmark)

    Sasmal, Pradip K; Krishna, C Vamsee; Sudheerkumar Adabala, S

    2015-01-01

    Kappa opioid receptor (KOR) is an important mediator of pain signaling and it is targeted for the treatment of various pains. Pharmacophore based mining of databases led to the identification of 2-aminobenzimidazole derivative as KOR agonists with selectivity over the other opioid receptors DOR a...... of novel benzimidazole derivatives as KOR agonists are described. The in vivo proof of principle for anti-nociceptive effect with a lead compound from this series is exemplified....

  19. Prediction of selective estrogen receptor beta agonist using open data and machine learning approach.

    Science.gov (United States)

    Niu, Ai-Qin; Xie, Liang-Jun; Wang, Hui; Zhu, Bing; Wang, Sheng-Qi

    2016-01-01

    Estrogen receptors (ERs) are nuclear transcription factors that are involved in the regulation of many complex physiological processes in humans. ERs have been validated as important drug targets for the treatment of various diseases, including breast cancer, ovarian cancer, osteoporosis, and cardiovascular disease. ERs have two subtypes, ER-α and ER-β. Emerging data suggest that the development of subtype-selective ligands that specifically target ER-β could be a more optimal approach to elicit beneficial estrogen-like activities and reduce side effects. Herein, we focused on ER-β and developed its in silico quantitative structure-activity relationship models using machine learning (ML) methods. The chemical structures and ER-β bioactivity data were extracted from public chemogenomics databases. Four types of popular fingerprint generation methods including MACCS fingerprint, PubChem fingerprint, 2D atom pairs, and Chemistry Development Kit extended fingerprint were used as descriptors. Four ML methods including Naïve Bayesian classifier, k-nearest neighbor, random forest, and support vector machine were used to train the models. The range of classification accuracies was 77.10% to 88.34%, and the range of area under the ROC (receiver operating characteristic) curve values was 0.8151 to 0.9475, evaluated by the 5-fold cross-validation. Comparison analysis suggests that both the random forest and the support vector machine are superior for the classification of selective ER-β agonists. Chemistry Development Kit extended fingerprints and MACCS fingerprint performed better in structural representation between active and inactive agonists. These results demonstrate that combining the fingerprint and ML approaches leads to robust ER-β agonist prediction models, which are potentially applicable to the identification of selective ER-β agonists.

  20. Antibodies against the melanocortin-4 receptor act as inverse agonists in vitro and in vivo.

    Science.gov (United States)

    Peter, Jean-Christophe; Nicholson, Janet R; Heydet, Déborah; Lecourt, Anne-Catherine; Hoebeke, Johan; Hofbauer, Karl G

    2007-06-01

    Functionally active antibodies (Abs) against central G-protein-coupled receptors have not yet been reported. We selected the hypothalamic melanocortin-4 receptor (MC4-R) as a target because of its crucial role in the regulation of energy homeostasis. A 15 amino acid sequence of the N-terminal (NT) domain was used as an antigen. This peptide showed functional activity in surface plasmon resonance experiments and in studies on HEK-293 cells overexpressing the human MC4-R (hMC4-R). Rats immunized against the NT peptide produced specific antibodies, which were purified and characterized in vitro. In HEK-293 cells, rat anti-NT Abs showed specific immunofluorescence labeling of hMC4-R. They reduced the production of cAMP under basal conditions and after stimulation with a synthetic MC4-R agonist. Rats immunized against the NT peptide developed a phenotype consistent with MC4-R blockade, that is, increased food intake and body weight, increased liver and fat pad weight, and elevated plasma triglycerides. In a separate experiment in rats, an increase in food intake could be produced after injection of purified Abs into the third ventricle. Similar results were obtained in rats injected with anti-NT Abs raised in rabbits. Our data show for the first time that active immunization of rats against the NT sequence of the MC4-R results in specific Abs, which appear to stimulate food intake by acting as inverse agonists in the hypothalamus.

  1. Prolonging survival of corneal transplantation by selective sphingosine-1-phosphate receptor 1 agonist.

    Directory of Open Access Journals (Sweden)

    Min Gao

    Full Text Available Corneal transplantation is the most used therapy for eye disorders. Although the cornea is somewhat an immune privileged organ, immune rejection is still the major problem that reduces the success rate. Therefore, effective chemical drugs that regulate immunoreactions are needed to improve the outcome of corneal transplantations. Here, a sphingosine-1-phosphate receptor 1 (S1P1 selective agonist was systematically evaluated in mouse allogeneic corneal transplantation and compared with the commonly used immunosuppressive agents. Compared with CsA and the non-selective sphingosine 1-phosphate (S1P receptor agonist FTY720, the S1P1 selective agonist can prolong the survival corneal transplantation for more than 30 days with a low immune response. More importantly, the optimal dose of the S1P1 selective agonist was much less than non-selective S1P receptor agonist FTY720, which would reduce the dose-dependent toxicity in drug application. Then we analyzed the mechanisms of the selected S1P1 selective agonist on the immunosuppression. The results shown that the S1P1 selective agonist could regulate the distribution of the immune cells with less CD4+ T cells and enhanced Treg cells in the allograft, moreover the expression of anti-inflammatory cytokines TGF-β1 and IL-10 unregulated which can reduce the immunoreactions. These findings suggest that S1P1 selective agonist may be a more appropriate immunosuppressive compound to effectively prolong mouse allogeneic corneal grafts survival.

  2. The effect of a full agonist/antagonist of the D1 receptor on locomotor activity sensorimotor gating and cognitive function in dizocilpine-treated rats

    Czech Academy of Sciences Publication Activity Database

    Bubeníková-Valešová, V.; Svoboda, Jan; Horáček, J.; Valeš, Karel

    2009-01-01

    Roč. 12, č. 7 (2009), s. 873-883 ISSN 1461-1457 R&D Projects: GA MŠk(CZ) 1M0517; GA ČR(CZ) GA309/07/0341; GA MZd(CZ) NR9178 Institutional research plan: CEZ:AV0Z50110509 Keywords : animal model * cognitive function * D1 receptor Subject RIV: FH - Neurology Impact factor: 4.874, year: 2009

  3. The dopamine D1 receptor agonist SKF81297 has dose-related effects on locomotor activity but is without effect in a CER trace conditioning procedure conducted with two versus four trials.

    Science.gov (United States)

    Pezze, M A; Marshall, H J; Cassaday, H J

    2016-08-01

    In an appetitively motivated procedure, we have previously reported that systemic treatment with the dopamine (DA) D1 receptor agonist SKF81297 (0.4 and 0.8 mg/kg) depressed acquisition at a 2 s inter-stimulus-interval (ISI), suitable to detect trace conditioning impairment. However since DA is involved in reinforcement processes, the generality of effects across appetitively- and aversively-motivated trace conditioning procedures cannot be assumed. The present study tested the effects of SKF81297 (0.4 and 0.8 mg/kg) in an established conditioned emotional response (CER) procedure. Trace-dependent conditioning was clearly shown in two experiments: while conditioning was relatively strong at a 3-s ISI, it was attenuated at a 30-s ISI. This was shown after two (Experiment 1) or four (Experiment 2) conditioning trials conducted in - as far as possible - the same CER procedure. Contrary to prediction, in neither experiment was there any indication that trace conditioning was attenuated by treatment with 0.4 or 0.8 mg/kg SKF81297. In the same rats, locomotor activity was significantly enhanced at the 0.8 mg/kg dose of SKF81297. These results suggest that procedural details of the trace conditioning variant in use are an important determinant of the profile of dopaminergic modulation.

  4. Treatment with a New Peroxisome Proliferator-Activated Receptor Gamma Agonist, Pyridinecarboxylic Acid Derivative, Increases Angiogenesis and Reduces Inflammatory Mediators in the Heart of Trypanosoma cruzi-Infected Mice

    Directory of Open Access Journals (Sweden)

    Federico Nicolás Penas

    2017-12-01

    Full Text Available Trypanosoma cruzi infection induces an intense inflammatory response in diverse host tissues. The immune response and the microvascular abnormalities associated with infection are crucial aspects in the generation of heart damage in Chagas disease. Upon parasite uptake, macrophages, which are involved in the clearance of infection, increase inflammatory mediators, leading to parasite killing. The exacerbation of the inflammatory response may lead to tissue damage. Peroxisome proliferator-activated receptor gamma (PPARγ is a ligand-dependent nuclear transcription factor that exerts important anti-inflammatory effects and is involved in improving endothelial functions and proangiogenic capacities. In this study, we evaluated the intermolecular interaction between PPARγ and a new synthetic PPARγ ligand, HP24, using virtual docking. Also, we showed that early treatment with HP24, decreases the expression of NOS2, a pro-inflammatory mediator, and stimulates proangiogenic mediators (vascular endothelial growth factor A, CD31, and Arginase I both in macrophages and in the heart of T. cruzi-infected mice. Moreover, HP24 reduces the inflammatory response, cardiac fibrosis and the levels of inflammatory cytokines (TNF-α, interleukin 6 released by macrophages of T. cruzi-infected mice. We consider that PPARγ agonists might be useful as coadjuvants of the antiparasitic treatment of Chagas disease, to delay, reverse, or preclude the onset of heart damage.

  5. Prediction of selective estrogen receptor beta agonist using open data and machine learning approach

    Directory of Open Access Journals (Sweden)

    Niu AQ

    2016-07-01

    for the classification of selective ER-β agonists. Chemistry Development Kit extended fingerprints and MACCS fingerprint performed better in structural representation between active and inactive agonists. Conclusion: These results demonstrate that combining the fingerprint and ML approaches leads to robust ER-β agonist prediction models, which are potentially applicable to the identification of selective ER-β agonists. Keywords: estrogen receptor subtype β, selective estrogen receptor modulators, quantitative structure-activity relationship models, machine learning approach

  6. (S)-homo-AMPA, a specific agonist at the mGlu6 subtype of metabotropic glutamic acid receptors

    DEFF Research Database (Denmark)

    Ahmadian, H; Nielsen, B; Bräuner-Osborne, Hans

    1997-01-01

    of the spectroscopic configurational assignments. The activities of 6 and 7 at ionotropic EAA (iGlu) receptors and at mGlu1-7 were studied. (S)-Homo-AMPA (6) was shown to be a specific agonist at mGlu6 (EC50 = 58 +/- 11 microM) comparable in potency with the endogenous mGlu agonist (S)-glutamic acid (EC50 = 20 +/- 3......Our previous publication (J. Med. Chem. 1996, 39, 3188-3194) described (RS)-2-amino-4-(3-hydroxy-5-methylisoxazol-4-yl)butyric acid (Homo-AMPA) as a highly selective agonist at the mGlu6 subtype of metabotropic excitatory amino acid (EAA) receptors. Homo-AMPA has already become a standard agonist...... microM). Although Homo-AMPA did not show significant effects at iGlu receptors, (R)-Homo-AMPA (7), which was inactive at mGlu1-7, turned out to be a weak N-methyl-D-aspartic acid (NMDA) receptor antagonist (IC50 = 131 +/- 18 microM)....

  7. Interactions of dopaminergic agonists and antagonists with dopaminergic D3 binding sites in rat striatum. Evidence that [3H]dopamine can label a high affinity agonist-binding state of the D1 dopamine receptor

    International Nuclear Information System (INIS)

    Leff, S.E.; Creese, I.

    1985-01-01

    The interactions of dopaminergic agonists and antagonists with 3 H-agonist labeled D3 dopaminergic binding sites of rat striatum have been characterized by radioligand-binding techniques. When the binding of [ 3 H]dopamine and [ 3 H]apomorphine to D2 dopamine receptors is blocked by the inclusion of D2 selective concentrations of unlabeled spiroperidol or domperidone, these ligands appear to label selectively the previously termed D3 binding site. Antagonist/[ 3 H]dopamine competition curves are of uniformly steep slope (nH . 1.0), suggesting the presence of a single D3 binding site. The relative potencies of antagonists to inhibit D3 specific [ 3 H]dopamine binding are significantly correlated with their potencies to block D1 dopamine receptors as measured by the inhibition of both dopamine-stimulated adenylate cyclase and [ 3 H]flupentixol-binding activities. The affinities of agonists to inhibit D3 specific [ 3 H]dopamine binding are also correlated with estimates of these agonists affinities for the high affinity binding component of agonist/[ 3 H]flupentixol competition curves. Both D3 specific [ 3 H] dopamine binding and the high affinity agonist-binding component of dopamine/[ 3 H]flupentixol competition curves show a similar sensitivity to guanine nucleotides. Taken together, these data strongly suggest that the D3 binding site is related to a high affinity agonist-binding state of the D1 dopamine receptor

  8. Structure and biological activity of endogenous and synthetic agonists of GPR119

    Science.gov (United States)

    Tyurenkov, I. N.; Ozerov, A. A.; Kurkin, D. V.; Logvinova, E. O.; Bakulin, D. A.; Volotova, E. V.; Borodin, D. D.

    2018-02-01

    A G-protein-coupled receptor, GPR119, is a promising pharmacological target for a new class of hypoglycaemic drugs with an original mechanism of action, namely, increase in the glucose-dependent incretin and insulin secretion. In 2005, the first ligands were found and in the subsequent years, a large number of GPR119 agonists were synthesized in laboratories in various countries; the safest and most promising agonists have entered phase I and II clinical trials as agents for the treatment of type 2 diabetes mellitus and obesity. The review describes the major endogenous GPR119 agonists and the main trends in the design and modification of synthetic structures for increasing the hypoglycaemic activity. The data on synthetic agonists are arranged according to the type of the central core of the molecules. The bibliography includes 104 references.

  9. Identification of Natural Compound Carnosol as a Novel TRPA1 Receptor Agonist

    Directory of Open Access Journals (Sweden)

    Chenxi Zhai

    2014-11-01

    Full Text Available The transient receptor potential ankyrin 1 (TRPA1 cation channel is one of the well-known targets for pain therapy. Herbal medicine is a rich source for new drugs and potentially useful therapeutic agents. To discover novel natural TRPA1 agonists, compounds isolated from Chinese herbs were screened using a cell-based calcium mobilization assay. Out of the 158 natural compounds derived from traditional Chinese herbal medicines, carnosol was identified as a novel agonist of TRPA1 with an EC50 value of 12.46 µM. And the agonistic effect of carnosol on TRPA1 could be blocked by A-967079, a selective TRPA1 antagonist. Furthermore, the specificity of carnosol was verified as it showed no significant effects on two other typical targets of TRP family member: TRPM8 and TRPV3. Carnosol exhibited anti-inflammatory and anti-nociceptive properties; the activation of TRPA1 might be responsible for the modulation of inflammatory nociceptive transmission. Collectively, our findings indicate that carnosol is a new anti-nociceptive agent targeting TRPA1 that can be used to explore further biological role in pain therapy.

  10. The Protective Role of PAC1-Receptor Agonist Maxadilan in BCCAO-Induced Retinal Degeneration.

    Science.gov (United States)

    Vaczy, A; Reglodi, D; Somoskeoy, T; Kovacs, K; Lokos, E; Szabo, E; Tamas, A; Atlasz, T

    2016-10-01

    A number of studies have proven that pituitary adenylate cyclase activating polypeptide (PACAP) is protective in neurodegenerative diseases. Permanent bilateral common carotid artery occlusion (BCCAO) causes severe degeneration in the rat retina. In our previous studies, protective effects were observed with PACAP1-38, PACAP1-27, and VIP but not with their related peptides, glucagon, or secretin in BCCAO. All three PACAP receptors (PAC1, VPAC1, VPAC2) appear in the retina. Molecular and immunohistochemical analysis demonstrated that the retinoprotective effects are most probably mainly mediated by the PAC1 receptor. The aim of the present study was to investigate the retinoprotective effects of a selective PAC1-receptor agonist maxadilan in BCCAO-induced retinopathy. Wistar rats were used in the experiment. After performing BCCAO, the right eye was treated with intravitreal maxadilan (0.1 or 1 μM), while the left eye was injected with vehicle. Sham-operated rats received the same treatment. Two weeks after the operation, retinas were processed for standard morphometric and molecular analysis. Intravitreal injection of 0.1 or 1 μM maxadilan caused significant protection in the thickness of most retinal layers and the number of cells in the GCL compared to the BCCAO-operated eyes. In addition, 1 μM maxadilan application was more effective than 0.1 μM maxadilan treatment in the ONL, INL, IPL, and the entire retina (OLM-ILM). Maxadilan treatment significantly decreased cytokine expression (CINC-1, IL-1α, and L-selectin) in ischemia. In summary, our histological and molecular analysis showed that maxadilan, a selective PAC1 receptor agonist, has a protective role in BCCAO-induced retinal degeneration, further supporting the role of PAC1 receptor conveying the retinoprotective effects of PACAP.

  11. Selective adenosine A2A receptor agonists and antagonists protect against spinal cord injury through peripheral and central effects

    Directory of Open Access Journals (Sweden)

    Esposito Emanuela

    2011-04-01

    Full Text Available Abstract Background Permanent functional deficits following spinal cord injury (SCI arise both from mechanical injury and from secondary tissue reactions involving inflammation. Enhanced release of adenosine and glutamate soon after SCI represents a component in the sequelae that may be responsible for resulting functional deficits. The role of adenosine A2A receptor in central ischemia/trauma is still to be elucidated. In our previous studies we have demonstrated that the adenosine A2A receptor-selective agonist CGS21680, systemically administered after SCI, protects from tissue damage, locomotor dysfunction and different inflammatory readouts. In this work we studied the effect of the adenosine A2A receptor antagonist SCH58261, systemically administered after SCI, on the same parameters. We investigated the hypothesis that the main action mechanism of agonists and antagonists is at peripheral or central sites. Methods Spinal trauma was induced by extradural compression of SC exposed via a four-level T5-T8 laminectomy in mouse. Three drug-dosing protocols were utilized: a short-term systemic administration by intraperitoneal injection, a chronic administration via osmotic minipump, and direct injection into the spinal cord. Results SCH58261, systemically administered (0.01 mg/kg intraperitoneal. 1, 6 and 10 hours after SCI, reduced demyelination and levels of TNF-α, Fas-L, PAR, Bax expression and activation of JNK mitogen-activated protein kinase (MAPK 24 hours after SCI. Chronic SCH58261 administration, by mini-osmotic pump delivery for 10 days, improved the neurological deficit up to 10 days after SCI. Adenosine A2A receptors are physiologically expressed in the spinal cord by astrocytes, microglia and oligodendrocytes. Soon after SCI (24 hours, these receptors showed enhanced expression in neurons. Both the A2A agonist and antagonist, administered intraperitoneally, reduced expression of the A2A receptor, ruling out the possibility that the

  12. Serotonin 2A receptor agonist binding in the human brain with [C]Cimbi-36

    DEFF Research Database (Denmark)

    Ettrup, A.; da Cunha-Bang, S.; McMahon, Barry P.

    2014-01-01

    [C]Cimbi-36 was recently developed as a selective serotonin 2A (5-HT) receptor agonist radioligand for positron emission tomography (PET) brain imaging. Such an agonist PET radioligand may provide a novel, and more functional, measure of the serotonergic system and agonist binding is more likely ....... Thus, we here describe [C]Cimbi-36 as the first agonist PET radioligand to successfully image and quantify 5-HT receptors in the human brain.Journal of Cerebral Blood Flow & Metabolism advance online publication, 30 April 2014; doi:10.1038/jcbfm.2014.68....... than antagonist binding to reflect 5-HT levels in vivo. Here, we show data from a first-in-human clinical trial with [C]Cimbi-36. In 29 healthy volunteers, we found high brain uptake and distribution according to 5-HT receptors with [C]Cimbi-36 PET. The two-tissue compartment model using arterial input...

  13. New benzylureas as a novel series of potent, nonpeptidic vasopressin V2 receptor agonists.

    Science.gov (United States)

    Yea, Christopher M; Allan, Christine E; Ashworth, Doreen M; Barnett, James; Baxter, Andy J; Broadbridge, Janice D; Franklin, Richard J; Hampton, Sally L; Hudson, Peter; Horton, John A; Jenkins, Paul D; Penson, Andy M; Pitt, Gary R W; Rivière, Pierre; Robson, Peter A; Rooker, David P; Semple, Graeme; Sheppard, Andy; Haigh, Robert M; Roe, Michael B

    2008-12-25

    Vasopressin (AVP) is a hormone that stimulates an increase in water permeability through activation of V2 receptors in the kidney. The analogue of AVP, desmopressin, has proven an effective drug for diseases where a reduction of urine output is desired. However, its peptidic nature limits its bioavailability. We report herein the discovery of potent, nonpeptidic, benzylurea derived agonists of the vasopressin V2 receptor. We describe substitutions on the benzyl group to give improvements in potency and subsequent modifications to the urea end group to provide improvements in solubility and increased oral efficacy in a rat model of diuresis. The lead compound 20e (VA106483) is reported for the first time and has been selected for clinical development.

  14. An Oral Selective Alpha-1A Adrenergic Receptor Agonist Prevents Doxorubicin Cardiotoxicity

    Directory of Open Access Journals (Sweden)

    Ju Youn Beak, PhD

    2017-02-01

    Full Text Available Summary: Alpha-1 adrenergic receptors (α1-ARs play adaptive and protective roles in the heart. Dabuzalgron is an oral selective α1A-AR agonist that was well tolerated in multiple clinical trials of treatment for urinary incontinence, but has never been used to treat heart disease in humans or animal models. In this study, the authors administered dabuzalgron to mice treated with doxorubicin (DOX, a widely used chemotherapeutic agent with dose-limiting cardiotoxicity that can lead to heart failure (HF. Dabuzalgron protected against DOX-induced cardiotoxicity, likely by preserving mitochondrial function. These results suggest that activating cardiac α1A-ARs with dabuzalgron, a well-tolerated oral agent, might represent a novel approach to treating HF. Key Words: alpha adrenergic receptors, anthracyclines, cardioprotection, catecholamines, heart failure

  15. Proton pump inhibitor Lansoprazole is a nuclear Liver X Receptor agonist

    Science.gov (United States)

    Cronican, Andrea A.; Fitz, Nicholas F.; Pham, Tam; Fogg, Allison; Kifer, Brionna; Koldamova, Radosveta; Lefterov, Iliya

    2010-01-01

    The liver X receptors (LXRα and LXRβ) are transcription factors that control the expression of genes primarily involved in cholesterol metabolism. In brain, in addition to normal neuronal function, cholesterol metabolism is important for APP proteolytic cleavage, secretase activities, Aβ aggregation and clearance. Particularly significant in this respect is the LXR mediated transcriptional control of APOE, which is the only proven risk factor for late onset Alzheimer’s disease. Using a transactivation reporter assay for screening pharmacologically active compounds and off patent drugs we identified the Proton Pump Inhibitor Lansoprazole as an LXR agonist. In secondary screens and counter-screening assays, it was confirmed that Lansoprazole directly activates LXR, increases the expression of LXR target genes in brain-derived human cell lines, and increases Abca1 and Apo-E protein levels in primary astrocytes derived from wild type but not LXRα/β double knockout mice. Other PPIs activate LXR as well, but the efficiency of activation depends on their structural similarities to Lansoprazole. The identification of widely used, drug with LXR agonist-like activity opens the possibility for systematic preclinical testing in at least two diseases – Alzheimer’s disease and atherosclerosis. PMID:20060385

  16. Ascorbic acid enables reversible dopamine receptor 3H-agonist binding

    International Nuclear Information System (INIS)

    Leff, S.; Sibley, D.R.; Hamblin, M.; Creese, I.

    1981-01-01

    The effects of ascorbic acid on dopaminergic 3 H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the 3 H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total 3 H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable 3 H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable 3 H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of 3 H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific 3 H-agonist binding to dopamine receptors

  17. Agonist and antagonist actions of antipsychotic agents at 5-HT1A receptors: a [35S]GTPgammaS binding study.

    Science.gov (United States)

    Newman-Tancredi, A; Gavaudan, S; Conte, C; Chaput, C; Touzard, M; Verrièle, L; Audinot, V; Millan, M J

    1998-08-21

    Recombinant human (h) 5-HT1A receptor-mediated G-protein activation was characterised in membranes of transfected Chinese hamster ovary (CHO) cells by use of guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS binding). The potency and efficacy of 21 5-HT receptor agonists and antagonists was determined. The agonists, 5-CT (carboxamidotryptamine) and flesinoxan displayed high affinity (subnanomolar Ki values) and high efficacy (Emax > 90%, relative to 5-HT = 100%). In contrast, ipsapirone, zalospirone and buspirone displayed partial agonist activity. EC50s for agonist stimulation of [35S]GTPgammaS binding correlated well with Ki values from competition binding (r = +0.99). Among the compounds tested for antagonist activity, methiothepin and (+)butaclamol exhibited 'inverse agonist' behaviour, inhibiting basal [35S]GTPgammaS binding. The actions of 17 antipsychotic agents were investigated. Clozapine and several putatively 'atypical' antipsychotic agents, including ziprasidone, quetiapine and tiospirone, exhibited partial agonist activity and marked affinity at h5-HT1A receptors, similar to their affinity at hD2 dopamine receptors. In contrast, risperidone and sertindole displayed low affinity at h5-HT1A receptors and behaved as 'neutral' antagonists, inhibiting 5-HT-stimulated [35S]GTPgammaS binding. Likewise the 'typical' neuroleptics, haloperidol, pimozide, raclopride and chlorpromazine exhibited relatively low affinity and 'neutral' antagonist activity at h5-HT1A receptors with Ki values which correlated with their respective Kb values. The present data show that (i) [35S]GTPgammaS binding is an effective method to evaluate the efficacy and potency of agonists and antagonists at recombinant human 5-HT1A receptors. (ii) Like clozapine, several putatively 'atypical' antipsychotic drugs display balanced serotonin h5-HT1A/dopamine hD2 receptor affinity and partial agonist activity at h5-HT1A receptors. (iii) Several 'typical' and some putatively 'atypical

  18. In vitro assessment of the agonist properties of the novel 5-HT1A receptor ligand, CUMI-101 (MMP), in rat brain tissue

    International Nuclear Information System (INIS)

    Hendry, Nicola; Christie, Isabel; Rabiner, Eugenii Alfredovich; Laruelle, Marc; Watson, Jeannette

    2011-01-01

    Introduction: Development of agonist positron emission tomography (PET) radioligands for the 5-HT neurotransmitter system is an important target to enable the understanding of human 5-HT function in vivo. [ 11 C]CUMI-101, proposed as the first 5-HT 1A receptor agonist PET ligand, has been reported to behave as a potent 5-HT 1A agonist in a cellular system stably expressing human recombinant 5-HT 1A receptors. In this study, we investigate the agonist properties of CUMI-101 in rat brain tissue. Methods: [ 35 S]-GTPγS binding studies were used to determine receptor function in HEK (human embryonic kidney) 293 cells transfected with human recombinant 5-HT 1A receptors and in rat cortex and rat hippocampal tissue, following administration of CUMI-101 and standard 5-HT1A antagonists (5-HT, 5-CT and 8-OH-DPAT). Results: CUMI-101 behaved as an agonist at human recombinant 5-HT 1A receptors (pEC 50 9.2). However, CUMI-101 did not show agonist activity in either rat cortex or hippocampus at concentrations up to 10 μM. In these tissues, CUMI-behaved as an antagonist with pK B s of 9.2 and 9.3, respectively. Conclusions: Our studies demonstrate that as opposed to its behavior in human recombinant system, in rat brain tissue CUMI-101 behaves as a potent 5-HT 1A receptor antagonist.

  19. Adenine Nucleotide Analogues Locked in a Northern Methanocarba Conformation: Enhanced Stability and Potency as P2Y1 Receptor Agonists

    Science.gov (United States)

    Ravi, R. Gnana; Kim, Hak Sung; Servos, Jörg; Zimmermann, Herbert; Lee, Kyeong; Maddileti, Savitri; Boyer, José L.; Harden, T. Kendall; Jacobson, Kenneth A.

    2016-01-01

    Preference for the Northern (N) ring conformation of the ribose moiety of nucleotide 5′-triphosphate agonists at P2Y1, P2Y2, P2Y4, and P2Y11 receptors, but not P2Y6 receptors, was established using a ring-constrained methanocarba (a 3.1.0-bicyclohexane) ring as a ribose substitute (Kim et al. J. Med. Chem. 2002, 45, 208–218.). We have now combined the ring-constrained (N)-methanocarba modification of adenine nucleotides with other functionalities known to enhance potency at P2 receptors. The potency of the newly synthesized analogues was determined in the stimulation of phospholipase C through activation of turkey erythrocyte P2Y1 or human P2Y1 and P2Y2 receptors stably expressed in astrocytoma cells. An (N)-methanocarba-2-methylthio-ADP analogue displayed an EC50 at the hP2Y1 receptor of 0.40 nM and was 55-fold more potent than the corresponding triphosphate and 16-fold more potent than the riboside 5′-diphosphate. 2-Cl–(N)-methanocarba-ATP and its N6-Me analogue were also highly selective, full agonists at P2Y1 receptors. The (N)-methanocarba-2-methylthio and 2-chloromonophosphate analogues were full agonists exhibiting micromolar potency at P2Y1 receptors, while the corresponding ribosides were inactive. Although β,γ-methylene-ATP was inactive at P2Y receptors, β,γ-methylene-(N)-methanocarba-ATP was a potent hP2Y1 receptor agonist with an EC50 of 160 nM and was selective versus hP2Y2 and hP2Y4 receptors. The rates of hydrolysis of Northern (N) and Southern (S) methanocarba analogues of AMP by rat 5′-ectonucleotidase were negligible. The rates of hydrolysis of the corresponding triphosphates by recombinant rat NTPDase1 and 2 were studied. Both isomers were hydrolyzed by NTPDase 1 at about half the rate of ATP hydrolysis. The (N) isomer was hardly hydrolyzed by NTPDase 2, while the (S) isomer was hydrolyzed at one-third of the rate of ATP hydrolysis. This suggests that new, more stable and selective nucleotide agonists may be designed on the basis of

  20. Liraglutide, a GLP-1 Receptor Agonist, Which Decreases Hypothalamic 5-HT2A Receptor Expression, Reduces Appetite and Body Weight Independently of Serotonin Synthesis in Mice

    Directory of Open Access Journals (Sweden)

    Katsunori Nonogaki

    2018-01-01

    Full Text Available A recent report suggested that brain-derived serotonin (5-HT is critical for maintaining weight loss induced by glucagon-like peptide-1 (GLP-1 receptor activation in rats and that 5-HT2A receptors mediate the feeding suppression and weight loss induced by GLP-1 receptor activation. Here, we show that changes in daily food intake and body weight induced by intraperitoneal administration of liraglutide, a GLP-1 receptor agonist, over 4 days did not differ between mice treated with the tryptophan hydroxylase (Tph inhibitor p-chlorophenylalanine (PCPA for 3 days and mice without PCPA treatment. Treatment with PCPA did not affect hypothalamic 5-HT2A receptor expression. Despite the anorexic effect of liraglutide disappearing after the first day of treatment, the body weight loss induced by liraglutide persisted for 4 days in mice treated with or without PCPA. Intraperitoneal administration of liraglutide significantly decreased the gene expression of hypothalamic 5-HT2A receptors 1 h after injection. Moreover, the acute anorexic effects of liraglutide were blunted in mice treated with the high-affinity 5-HT2A agonist (4-bromo-3,6-dimethoxybenzocyclobuten-1-yl methylamine hydrobromide 14 h or 24 h before liraglutide injection. These findings suggest that liraglutide reduces appetite and body weight independently of 5-HT synthesis in mice, whereas GLP-1 receptor activation downregulates the gene expression of hypothalamic 5-HT2A receptors.

  1. Unraveling the high- and low-sensitivity agonist responses of nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Harpsøe, Kasper; Ahring, Philip K; Christensen, Jeppe K

    2011-01-01

    The neuronal a4ß2 nicotinic acetylcholine receptors exist as two distinct subtypes, (a4)(2)(ß2)(3) and (a4)(3)(ß2)(2), and biphasic responses to acetylcholine and other agonists have been ascribed previously to coexistence of these two receptor subtypes. We offer a novel and radical explanation...

  2. Bioassay directed identification of natural aryl hydrocarbon-receptor agonists in marmalade

    NARCIS (Netherlands)

    Ede, van K.I.; Li, A.; Antunes Fernandes, E.C.; Mulder, P.P.J.; Peijnenburg, A.A.C.M.; Hoogenboom, L.A.P.

    2008-01-01

    Citrus fruit and citrus fruit products, like grapefruit, lemon and marmalade were shown to contain aryl hydrocarbon receptor (AhR) agonists, as detected with the DR CALUX® bioassay. This is of interest regarding the role of the Ah-receptor pathway in the adverse effects of dioxins, PCBs and other

  3. Tweaking agonist efficacy at N-methyl-D-aspartate receptors by site-directed mutagenesis

    DEFF Research Database (Denmark)

    Hansen, Kasper B; Clausen, Rasmus P; Bjerrum, Esben J

    2005-01-01

    The structural basis for partial agonism at N-methyl-D-aspartate (NMDA) receptors is currently unresolved. We have characterized several partial agonists at the NR1/NR2B receptor and investigated the mechanisms underlying their reduced efficacy by introducing mutations in the glutamate binding site...

  4. Identification of potent, nonabsorbable agonists of the calcium-sensing receptor for GI-specific administration.

    Science.gov (United States)

    Sparks, Steven M; Spearing, Paul K; Diaz, Caroline J; Cowan, David J; Jayawickreme, Channa; Chen, Grace; Rimele, Thomas J; Generaux, Claudia; Harston, Lindsey T; Roller, Shane G

    2017-10-15

    Modulation of gastrointestinal nutrient sensing pathways provides a promising a new approach for the treatment of metabolic diseases including diabetes and obesity. The calcium-sensing receptor has been identified as a key receptor involved in mineral and amino acid nutrient sensing and thus is an attractive target for modulation in the intestine. Herein we describe the optimization of gastrointestinally restricted calcium-sensing receptor agonists starting from a 3-aminopyrrolidine-containing template leading to the identification of GI-restricted agonist 19 (GSK3004774). Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Biostructural and pharmacological studies of bicyclic analogues of the 3-isoxazolol glutamate receptor agonist ibotenic acid

    DEFF Research Database (Denmark)

    Frydenvang, Karla Andrea; Pickering, Darryl S; Greenwood, Jeremy R

    2010-01-01

    We describe an improved synthesis and detailed pharmacological characterization of the conformationally restricted analogue of the naturally occurring nonselective glutamate receptor agonist ibotenic acid (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-7-carboxylic acid (7-HPCA, 5......) at AMPA receptor subtypes. Compound 5 was shown to be a subtype-discriminating agonist at AMPA receptors with higher binding affinity and functional potency at GluA1/2 compared to GluA3/4, unlike the isomeric analogue (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-5-carboxylic acid (5-HPCA, 4...

  6. Development of a new knock-in mouse model and evaluation of pharmacological activities of lusutrombopag, a novel, nonpeptidyl small-molecule agonist of the human thrombopoietin receptor c-Mpl.

    Science.gov (United States)

    Yoshida, Hiroshi; Yamada, Hajime; Nogami, Wataru; Dohi, Keiji; Kurino-Yamada, Tomomi; Sugiyama, Koji; Takahashi, Koji; Gahara, Yoshinari; Kitaura, Motoji; Hasegawa, Minoru; Oshima, Itsuki; Kuwabara, Kenji

    2018-03-01

    Lusutrombopag (S-888711), an oral small-molecule thrombopoietin receptor (TPOR) agonist, has gained first approval as a drug to treat thrombocytopenia of chronic liver disease in patients undergoing elective invasive procedures in Japan. Preclinical studies were performed to evaluate its efficacy against megakaryopoiesis and thrombopoiesis. To investigate the proliferative activity and efficacy of megakaryocytic colony formation via human TPOR, lusutrombopag was applied to cultured human c-Mpl-expressing Ba/F3 (Ba/F3-hMpl) cells and human bone marrow-derived CD34-positive cells, respectively. Lusutrombopag caused a robust increase in Ba/F3-hMpl cells by activating pathways in a manner similar to that of thrombopoietin and induced colony-forming units-megakaryocyte and polyploid megakaryocytes in human CD34-positive cells. Because lusutrombopag has high species specificity for human TPOR, there was no suitable experimental animal model for drug evaluation, except for immunodeficient mouse-based xenograft models. Therefore, a novel genetically modified knock-in mouse, TPOR-Ki/Shi, was developed by replacing mouse Mpl with human-mouse chimera Mpl. In TPOR-Ki/Shi mice, lusutrombopag significantly increased circulating platelets in a dose-dependent manner during 21-day repeated oral administration. Histopathological study of the TPOR-Ki/Shi mice on day 22 also revealed a significant increase in megakaryocytes in the bone marrow. These results indicate that lusutrombopag acts on human TPOR to upregulate differentiation and proliferation of megakaryocytic cells, leading to platelet production. Copyright © 2018 ISEH – Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.

  7. Enhanced induction of apoptosis by combined treatment of human carcinoma cells with X rays and death receptor agonists

    International Nuclear Information System (INIS)

    Hamasu, Taku; Inanami, Osamu; Asanuma, Taketoshi; Kuwabara, Mikinori

    2005-01-01

    The death receptors Fas and DR5 are known to be expressed not only in immune cells but also in various tumor cells. The aim of the present study was to determine whether X irradiation enhanced induction of apoptosis in Tp53 wild type and Tp53-mutated tumor cell lines treated with agonists against these death receptors. We showed that 5 Gy of X irradiation significantly up-regulated the expression of death receptors Fas and DR5 on the plasma membrane in gastric cancer cell lines MKN45 and MKN28, lung cancer cell line A549, and prostate cancer cell line DU145, and that subsequent treatments with agonistic molecules for these death receptors, Fas antibody CHl1 and TRAIL, increased the formation of active fragment p20 of caspase 3 followed by the induction of apoptosis. This death-receptor-mediated apoptosis was independent of Tp53 status since MKN28 and DU145 were Tp53-mutated. The post-irradiation treatment of the cells with N-acetyl-L-cysteine (NAC) abolished the up-regulation of the expression of Fas and DR5 on the plasma membrane. NAC also attenuated the increase in the formation of p20 and the induction of apoptosis by agonistic molecules. These results suggested that the increase in the induction of apoptosis by combined treatment with X irradiation and CHl1 or TRAIL occurred through a change of the intracellular redox state independent of Tp53 status in human carcinoma cell lines. (author)

  8. Hypothermia in mouse is caused by adenosine A1 and A3 receptor agonists and AMP via three distinct mechanisms.

    Science.gov (United States)

    Carlin, Jesse Lea; Jain, Shalini; Gizewski, Elizabeth; Wan, Tina C; Tosh, Dilip K; Xiao, Cuiying; Auchampach, John A; Jacobson, Kenneth A; Gavrilova, Oksana; Reitman, Marc L

    2017-03-01

    Small mammals have the ability to enter torpor, a hypothermic, hypometabolic state, allowing impressive energy conservation. Administration of adenosine or adenosine 5'-monophosphate (AMP) can trigger a hypothermic, torpor-like state. We investigated the mechanisms for hypothermia using telemetric monitoring of body temperature in wild type and receptor knock out (Adora1 -/- , Adora3 -/- ) mice. Confirming prior data, stimulation of the A 3 adenosine receptor (AR) induced hypothermia via peripheral mast cell degranulation, histamine release, and activation of central histamine H 1 receptors. In contrast, A 1 AR agonists and AMP both acted centrally to cause hypothermia. Commonly used, selective A 1 AR agonists, including N 6 -cyclopentyladenosine (CPA), N 6 -cyclohexyladenosine (CHA), and MRS5474, caused hypothermia via both A 1 AR and A 3 AR when given intraperitoneally. Intracerebroventricular dosing, low peripheral doses of Cl-ENBA [(±)-5'-chloro-5'-deoxy-N 6 -endo-norbornyladenosine], or using Adora3 -/- mice allowed selective stimulation of A 1 AR. AMP-stimulated hypothermia can occur independently of A 1 AR, A 3 AR, and mast cells. A 1 AR and A 3 AR agonists and AMP cause regulated hypothermia that was characterized by a drop in total energy expenditure, physical inactivity, and preference for cooler environmental temperatures, indicating a reduced body temperature set point. Neither A 1 AR nor A 3 AR was required for fasting-induced torpor. A 1 AR and A 3 AR agonists and AMP trigger regulated hypothermia via three distinct mechanisms. Published by Elsevier Ltd.

  9. Influence of TCDD and natural Ah receptor agonists on benzo[a]pyrene-DNA adduct formation in the Caco-2 human colon cell line

    NARCIS (Netherlands)

    Waard, de W.J.; Kok, de T.M.C.M.; Maas, L.M.; Peijnenburg, A.A.C.M.; Hoogenboom, L.A.P.; Aarts, H.J.M.; Schooten, van F.J.

    2008-01-01

    Several compounds originating from cruciferous vegetables and citrus fruits bind to and activate the aryl hydrocarbon receptor (AhR). This receptor plays an important role in the toxicity of the known tumour promoter and potent AhR-agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). However,

  10. A human intervention study with foods containing natural Ah-receptor agonists does not significantly show AhR-mediated effects as measured in blood cells and urine

    NARCIS (Netherlands)

    Waard, de W.J.; Peijnenburg, A.A.C.M.; Baykus, H.; Aarts, H.J.M.; Hoogenboom, L.A.P.; Schooten, van F.J.; Kok, E.J.

    2008-01-01

    Binding and activation of the aryl hydrocarbon receptor (AhR) is thought to be an essential step in the toxicity of the environmental pollutants dioxins and dioxin-like PCBs. However, also a number of natural compounds, referred to as NAhRAs (natural Ah-receptor agonists), which are present in, for

  11. Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response.

    Science.gov (United States)

    Zhou, Wei; Zhang, Xuan; Zhu, Cai-Lian; He, Zhi-Yan; Liang, Jing-Ping; Song, Zhong-Chen

    2016-01-01

    "Perioceutics" including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential "perioceutics" treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation. Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA). Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgpA, rgpB, hag

  12. Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response.

    Directory of Open Access Journals (Sweden)

    Wei Zhou

    Full Text Available "Perioceutics" including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential "perioceutics" treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS-induced inflammation.Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM. The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8 was measured by enzyme-linked immunosorbent assay (ELISA.Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgp

  13. Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

    Science.gov (United States)

    Newman-Tancredi, Adrian; Cussac, Didier; Quentric, Yann; Touzard, Manuelle; Verrièle, Laurence; Carpentier, Nathalie; Millan, Mark J

    2002-11-01

    Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their

  14. Dynamical Binding Modes Determine Agonistic and Antagonistic Ligand Effects in the Prostate-Specific G-Protein Coupled Receptor (PSGR).

    Science.gov (United States)

    Wolf, Steffen; Jovancevic, Nikolina; Gelis, Lian; Pietsch, Sebastian; Hatt, Hanns; Gerwert, Klaus

    2017-11-22

    We analysed the ligand-based activation mechanism of the prostate-specific G-protein coupled receptor (PSGR), which is an olfactory receptor that mediates cellular growth in prostate cancer cells. Furthermore, it is an olfactory receptor with a known chemically near identic antagonist/agonist pair, α- and β-ionone. Using a combined theoretical and experimental approach, we propose that this receptor is activated by a ligand-induced rearrangement of a protein-internal hydrogen bond network. Surprisingly, this rearrangement is not induced by interaction of the ligand with the network, but by dynamic van der Waals contacts of the ligand with the involved amino acid side chains, altering their conformations and intraprotein connectivity. Ligand recognition in this GPCR is therefore highly stereo selective, but seemingly lacks any ligand recognition via polar contacts. A putative olfactory receptor-based drug design scheme will have to take this unique mode of protein/ligand action into account.

  15. Effects of structural modifications of N-CPM-normorphine derivatives on agonist and antagonist activities in isolated organs.

    Science.gov (United States)

    Riba, P; Tóth, Z; Hosztafi, S; Friedmann, T; Fürst, S

    2003-01-01

    The agonistic and antagonistic properties of N-cyclopropylmethyl (N-CPM) morphine derivatives were observed in mouse vas deferens (MVD), longitudinal muscle of guinea pig ileum (GPI) and rabbit vas deferens (LVD). In MVD the K(e) values of the titled compounds (N-CPM-morphine, N-CPM-isomorphine, N-CPM-dihydromorphine, N-CPM-dihydroisomorpPhine, N-CPM-dihydromorphone and naltrexone) were measured for mu-, kappa- and delta-receptors using normorphine, ethylketocyclazocine (EKC) and D-Pen2-D-Pen5-enkephaline (DPDPE) as selective agonists on the receptors, respectively. For mu-receptors of MVD the tested compounds showed similar affinity. For kappa-receptors the non-iso-6-OH derivatives possessed much less affinity than the iso-derivatives. Similar difference could be observed for delta-receptors. The agonistic activities of these compounds in MVD were observed to be between 0-20% of the inhibition of muscle contractions. In GPI the compounds except naltrexone possessed strong agonistic activities effectively antagonized by nor-binaltorphimine (nor-BNI) (K(e) of nor-BNI was 0.23 nM) suggesting that they were strong kappa-receptor agonists. We investigated these agents in LVD too, which contains kappa-receptors, but they did not produce any agonist potencies. It raises the possibility that the kappa-receptor subtypes of LVD and MVD are different from the kappa-receptor subtype of GPI or the vasa deferentia contain much fewer kappa-receptors than GPI and the intrinsic activities of these compounds are too small to reach the 50% inhibition of the contractions.

  16. Cannabinoid CB2 receptor agonists protect the striatum against malonate toxicity: relevance for Huntington’s disease

    Science.gov (United States)

    Sagredo, Onintza; González, Sara; Aroyo, Ilia; Pazos, María Ruth; Benito, Cristina; Lastres-Becker, Isabel; Romero, Juan P.; Tolón, Rosa M.; Mechoulam, Raphael; Brouillet, Emmanuel; Romero, Julián; Fernández-Ruiz, Javier

    2009-01-01

    Cannabinoid agonists might serve as neuroprotective agents in neurodegenerative disorders. Here, we examined this hypothesis in a rat model of Huntington’s disease (HD) generated by intrastriatal injection of the mitochondrial complex II inhibitor malonate. Our results showed that only compounds able to activate CB2 receptors were capable of protecting striatal projection neurons from malonate-induced death. That CB2 receptor agonists are neuroprotective was confirmed by using the selective CB2 receptor antagonist, SR144528, and by the observation that mice deficient in CB2 receptor were more sensitive to malonate than wild-type animals. CB2 receptors are scarce in the striatum in healthy conditions but they are markedly up-regulated after the lesion with malonate. Studies of double immunostaining revealed a significant presence of CB2 receptors in cells labelled with the marker of reactive microglia OX-42, and also in cells labelled with GFAP (a marker of astrocytes). We further showed that the activation of CB2 receptors significantly reduced the levels of tumor necrosis factor-α (TNF-α) that had been increased by the lesion with malonate. In summary, our results demonstrate that stimulation of CB2 receptors protect the striatum against malonate toxicity, likely through a mechanism involving glial cells, in particular reactive microglial cells in which CB2 receptors would be up-regulated in response to the lesion. Activation of these receptors would reduce the generation of proinflammatory molecules like TNF-α. Altogether our results support the hypothesis that CB2 receptors could constitute a therapeutic target to slowdown neurodegeneration in HD. PMID:19115380

  17. Effects of Trace Amine-associated Receptor 1 Agonists on the Expression, Reconsolidation, and Extinction of Cocaine Reward Memory.

    Science.gov (United States)

    Liu, Jian-Feng; Thorn, David A; Zhang, Yanan; Li, Jun-Xu

    2016-07-01

    As a modulator of dopaminergic system, trace amine-associated receptor 1 has been shown to play a critical role in regulating the rewarding properties of additive drugs. It has been demonstrated that activation of trace amine-associated receptor 1 decreased the abuse-related behaviors of cocaine in rats. However, the role of trace amine-associated receptor 1 in specific stages of cocaine reward memory is still unclear. Here, using a cocaine-induced conditioned place preference model, we tested the effects of a selective trace amine-associated receptor 1 agonist RO5166017 on the expression, reconsolidation, and extinction of cocaine reward memory. We found that RO5166017 inhibited the expression but not retention of cocaine-induced conditioned place preference. RO5166017 had no effect on the reconsolidation of cocaine reward memory. Pretreatment with RO5166017 before extinction hindered the formation of extinction long-term memory. RO5166017 did not affect the movement during the conditioned place preference test, indicating the inhibitory effect of RO5166017 on the expression of cocaine-induced conditioned place preference was not caused by locomotion inhibition. Using a cocaine i.v. self-administration model, we found that the combined trace amine-associated receptor 1 partial agonist RO5263397 with extinction had no effect on the following cue- and drug-induced reinstatement of cocaine-seeking behavior. Repeated administration of the trace amine-associated receptor 1 agonist during extinction showed a continually inhibitory effect on the expression of cocaine reward memory both in cocaine-induced conditioned place preference and cocaine self-administration models. Taken together, these results indicate that activation of trace amine-associated receptor 1 specifically inhibited the expression of cocaine reward memory. The inhibitory effect of trace amine-associated receptor 1 agonists on cocaine reward memory suggests that trace amine-associated receptor 1

  18. Adenosine A(2A) receptor dynamics studied with the novel fluorescent agonist Alexa488-APEC.

    Science.gov (United States)

    Brand, Frank; Klutz, Athena M; Jacobson, Kenneth A; Fredholm, Bertil B; Schulte, Gunnar

    2008-08-20

    G protein-coupled receptors, such as the adenosine A(2A) receptor, are dynamic proteins, which undergo agonist-dependent redistribution from the cell surface to intracellular membranous compartments, such as endosomes. In order to study the kinetics of adenosine A(2A) receptor redistribution in living cells, we synthesized a novel fluorescent agonist, Alexa488-APEC. Alexa488-APEC binds to adenosine A(2A) (K(i)=149+/-27 nM) as well as A(3) receptors (K(i)=240+/-160 nM) but not to adenosine A(1) receptors. Further, we characterized the dose-dependent increase in Alexa488-APEC-induced cAMP production as well as cAMP response element binding (CREB) protein phosphorylation, verifying the ligand's functionality at adenosine A(2A) but not A(2B) receptors. In live-cell imaging studies, Alexa488-APEC-induced adenosine A(2A) receptor internalization, which was blocked by the competitive reversible antagonist ZM 241385 and hyperosmolaric sucrose. Further, internalized adenosine A(2A) receptors co-localized with clathrin and Rab5, indicating that agonist stimulation promotes adenosine A(2A) receptor uptake through a clathrin-dependent mechanism to Rab5-positive endosomes. The basic characterization of Alexa488-APEC described here showed that it provides a useful tool for tracing adenosine A(2A) receptors in vitro.

  19. Procaine rapidly inactivates acetylcholine receptors from Torpedo and competes with agonist for inhibition sites

    International Nuclear Information System (INIS)

    Forman, S.A.; Miller, K.W.

    1989-01-01

    The relationship between the high-affinity procaine channel inhibition site and the agonist self-inhibition site on acetylcholine receptors (AChRs) from Torpedo electroplaque was investigated by using rapid 86 Rb + quenched-flux assays at 4 degree C in native AChR-rich vesicles on which 50-60% of ACh activation sites were blocked with α-bungarotoxin (α-BTX). In the presence of channel-activating acetylcholine (ACh) concentrations alone, AChR undergoes one phase of inactivation in under a second. Addition of procaine produces two-phase inactivation similar to that seen with self-inhibiting ACh concentrations rapid inactivation complete in 30-75 ms is followed by fast desensitization at the same k d observed without procaine. The dependence of k r on [procaine] is consistent with a bimolecular association between procaine and its AChR site. Inhibition of AChR function by mixtures of procaine plus self-inhibiting concentrations of ACh or suberyldicholine was studied by reducing the level of α-BTX block in vesicles. The data support a mechanism where procaine binds preferentially to the open-channel AChR state, since no procaine-induced inactivation is observed without agonist and k r 's dependence on [ACh] in channel-activating range closely parallels that of 86 Rb + flux response to ACh

  20. BIASED AGONISM OF THREE DIFFERENT CANNABINOID RECEPTOR AGONISTS IN MOUSE BRAIN CORTEX

    Directory of Open Access Journals (Sweden)

    Rebeca Diez-Alarcia

    2016-11-01

    Full Text Available Cannabinoid receptors are able to couple to different families of G-proteins when activated by an agonist drug. It has been suggested that different intracellular responses may be activated depending on the ligand. The goal of the present study was to characterize the pattern of G protein subunit stimulation triggered by three different cannabinoid ligands, THC, WIN55212-2 and ACEA in mouse brain cortex.Stimulation of the [35S]GTPS binding coupled to specific immunoprecipitation with antibodies against different subtypes of G proteins (Gαi1, Gαi2, Gαi3, Gαo, Gαz, Gαs, Gαq/11, and Gα12/13, in the presence of Δ9-THC, WIN55212-2 and ACEA (submaximal concentration 10 µM was determined by Scintillation Proximity Assay (SPA technique in mouse cortex of wild type, CB1 knock-out, CB2 knock-out and CB1/CB2 double knock-out mice. Results show that, in mouse brain cortex, cannabinoid agonists are able to significantly stimulate not only the classical inhibitory Gαi/o subunits but also other G subunits like Gαz, Gαq/11, and Gα12/13. Moreover, the specific pattern of G protein subunit activation is different depending on the ligand. In conclusion, our results demonstrate that, in mice brain native tissue, different exogenous cannabinoid ligands are able to selectively activate different inhibitory and non-inhibitory Gα protein subtypes, through the activation of CB1 and/or CB2 receptors. Results of the present study may help to understand the specific molecular pathways involved in the pharmacological effects of cannabinoid-derived drugs.

  1. The effects of dopamine receptor 1 and 2 agonists and antagonists on sexual and aggressive behaviors in male green anoles.

    Science.gov (United States)

    Smith, Alexandra N; Kabelik, David

    2017-01-01

    The propensity to exhibit social behaviors during interactions with same-sex and opposite-sex conspecifics is modulated by various neurotransmitters, including dopamine. Dopamine is a conserved neurotransmitter among vertebrates and dopaminergic receptors are also highly conserved among taxa. Activation of D1 and D2 dopamine receptor subtypes has been shown to modulate social behaviors, especially in mammalian and avian studies. However, the specific behavioral functions of these receptors vary across taxa. In reptiles there have been few studies examining the relationship between dopaminergic receptors and social behaviors. We therefore examined the effects of D1 and D2 agonists and antagonists on sexual and aggressive behaviors in the male green anole lizard (Anolis carolinensis). Treatment with high doses of both D1 and D2 agonists was found to impair both sexual and aggressive behaviors. However, the D1 agonist treatment was also found to impair motor function, suggesting that those effects were likely nonspecific. Lower doses of both agonists and antagonists failed to affect social behaviors. These findings provide some evidence for D2 receptor regulation of social behaviors, but in contrast with previous research, these effects are all inhibitory and no effects were found for manipulations of D1 receptors. A potential reason for the lack of more widespread effects on social behaviors using moderate or low drug doses is that systemic injection of drugs resulted in effects throughout the whole brain, thus affecting counteracting circuits which negated one another, making measurable changes in behavioral output difficult to detect. Future studies should administer drugs directly into brain regions known to regulate sexual and aggressive behaviors.

  2. The effects of dopamine receptor 1 and 2 agonists and antagonists on sexual and aggressive behaviors in male green anoles.

    Directory of Open Access Journals (Sweden)

    Alexandra N Smith

    Full Text Available The propensity to exhibit social behaviors during interactions with same-sex and opposite-sex conspecifics is modulated by various neurotransmitters, including dopamine. Dopamine is a conserved neurotransmitter among vertebrates and dopaminergic receptors are also highly conserved among taxa. Activation of D1 and D2 dopamine receptor subtypes has been shown to modulate social behaviors, especially in mammalian and avian studies. However, the specific behavioral functions of these receptors vary across taxa. In reptiles there have been few studies examining the relationship between dopaminergic receptors and social behaviors. We therefore examined the effects of D1 and D2 agonists and antagonists on sexual and aggressive behaviors in the male green anole lizard (Anolis carolinensis. Treatment with high doses of both D1 and D2 agonists was found to impair both sexual and aggressive behaviors. However, the D1 agonist treatment was also found to impair motor function, suggesting that those effects were likely nonspecific. Lower doses of both agonists and antagonists failed to affect social behaviors. These findings provide some evidence for D2 receptor regulation of social behaviors, but in contrast with previous research, these effects are all inhibitory and no effects were found for manipulations of D1 receptors. A potential reason for the lack of more widespread effects on social behaviors using moderate or low drug doses is that systemic injection of drugs resulted in effects throughout the whole brain, thus affecting counteracting circuits which negated one another, making measurable changes in behavioral output difficult to detect. Future studies should administer drugs directly into brain regions known to regulate sexual and aggressive behaviors.

  3. Dopamine agonist increases risk taking but blunts reward-related brain activity.

    Directory of Open Access Journals (Sweden)

    Jordi Riba

    Full Text Available The use of D2/D3 dopaminergic agonists in Parkinson's disease (PD may lead to pathological gambling. In a placebo-controlled double-blind study in healthy volunteers, we observed riskier choices in a lottery task after administration of the D3 receptor-preferring agonist pramipexole thus mimicking risk-taking behavior in PD. Moreover, we demonstrate decreased activation in the rostral basal ganglia and midbrain, key structures of the reward system, following unexpected high gains and therefore propose that pathological gambling in PD results from the need to seek higher rewards to overcome the blunted response in this system.

  4. Free Fatty Acid Receptor 1 (FFA1/GPR40) Agonists

    DEFF Research Database (Denmark)

    Christiansen, Elisabeth; Due-Hansen, Maria E; Urban, Christian

    2012-01-01

    FFA1 (GPR40) is a new target for treatment of type 2 diabetes. We recently identified the potent FFA1 agonist TUG-469 (5). Inspired by the structurally related TAK-875, we explored the effects of a mesylpropoxy appendage on 5. The appendage significantly lowers lipophilicity and improves metaboli...

  5. Differential regulation by agonist and phorbol ester of cloned m1 and m2 muscarinic acetylcholine receptors in mouse Y1 adrenal cells and in Y1 cells deficient in cAMP-dependent protein kinase

    International Nuclear Information System (INIS)

    Scherer, N.M.; Nathanson, N.M.

    1990-01-01

    Cloned muscarinic acetylcholine m1 and m2 receptors were expressed in stably transfected mouse Y1 adrenal cells and in a variant Y1 line, Kin-8, which is deficient in cAMP-dependent protein kinase activity (PKA - ). m1 and m2 receptors were rapidly internalized following exposure of transfected PKA + or PKA - cells to the muscarinic agonist carbachol. Thus, agonist-dependent internalization of m1 and m2 did not require PKA activity. A differential effect of PKA on regulation by agonist of the m2 receptor, but not the m1 receptor, was unmasked in PKA - cells. These data indicate that the basal activity of PKA may modulate the agonist-dependent internalization of the m2 receptor, but not the m1 receptor. The internalization of the m1 and m2 receptors in both PKA + and PKA - cells was accompanied by desensitization of functional responses. Exposure of PKA + cells to 10 -7 M phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, resulted in a 30 ± 9% decrease in the number of m1 receptors on the cell surface. The m2 receptor was not internalized following treatment of either PKA + or PKA - cells with PMA. Thus, the m1 and m2 receptors show differential sensitivity to internalization by PMA. Agonist-dependent internalization of the m1 receptor appeared to be independent of activation of PKC because (1) agonist-dependent internalization of m1 was not attenuated in PKA - cells, (2) the rate and extent of internalization of m1 in cells exposed to PMA were less than those in cells exposed to agonist, and (3) treatment of cells with concanavalin A selectivity blocked internalization of m1 in cells exposed to PMA, but not to agonist. The effects of agonist and PMA on receptor internalization were not additive. Exposure of PKA + or PKA - cells to PMA reduced the magnitude of pilocarpine-stimulated PI hydrolysis by about 25%

  6. Suppression of the cough reflex by α2-adrenergic receptor agonists in the rabbit

    Science.gov (United States)

    Cinelli, Elenia; Bongianni, Fulvia; Pantaleo, Tito; Mutolo, Donatella

    2013-01-01

    The α2-adrenergic receptor agonist clonidine has been shown to inhibit citric acid-induced cough responses in guinea pigs when administered by aerosol, but not orally. In contrast, oral or inhaled clonidine had no effect on capsaicin-induced cough and reflex bronchoconstriction in humans. In addition, intravenous administration of clonidine has been shown to depress fentanyl-induced cough in humans. We investigated the effects of the α2-adrenergic receptor agonists, clonidine and tizanidine, on cough responses induced by mechanical and chemical (citric acid) stimulation of the tracheobronchial tree. Drugs were microinjected (30–50 nL) into the caudal nucleus tractus solitarii (cNTS) and the caudal ventral respiratory group (cVRG) as well as administered intravenously in pentobarbital sodium-anesthetized, spontaneously breathing rabbits. Bilateral microinjections of clonidine into the cNTS or the cVRG reduced cough responses at 0.5 mmol/L and abolished the cough reflex at 5 mmol/L. Bilateral microinjections of 0.5 mmol/L tizanidine into the cNTS completely suppressed cough responses, whereas bilateral microinjections of 5 mmol/L into the cVRG only caused mild reductions in them. Depressant effects on the cough reflex of clonidine and tizanidine were completely reverted by microinjections of 10 mmol/L yohimbine. Intravenous administration of clonidine (80–120 μg/kg) or tizanidine (150–300 μg/kg) strongly reduced or completely suppressed cough responses. These effects were reverted by intravenous administration of yohimbine (300 μg/kg). The results demonstrate that activation of α2-adrenergic receptors in the rabbit exerts potent inhibitory effects on the central mechanism generating the cough motor pattern with a clear action at the level of the cNTS and the cVRG. PMID:24400133

  7. Effects of BMS-902483, an α7 nicotinic acetylcholine receptor partial agonist, on cognition and sensory gating in relation to receptor occupancy in rodents.

    Science.gov (United States)

    Pieschl, Rick L; Miller, Regina; Jones, Kelli M; Post-Munson, Debra J; Chen, Ping; Newberry, Kimberly; Benitex, Yulia; Molski, Thaddeus; Morgan, Daniel; McDonald, Ivar M; Macor, John E; Olson, Richard E; Asaka, Yukiko; Digavalli, Siva; Easton, Amy; Herrington, James; Westphal, Ryan S; Lodge, Nicholas J; Zaczek, Robert; Bristow, Linda J; Li, Yu-Wen

    2017-07-15

    The α7 nicotinic acetylcholine receptor is thought to play an important role in human cognition. Here we describe the in vivo effects of BMS-902483, a selective potent α7 nicotinic acetylcholine receptor partial agonist, in relationship to α7 nicotinic acetylcholine receptor occupancy. BMS-902483 has low nanomolar affinity for rat and human α7 nicotinic acetylcholine receptors and elicits currents in cells expressing human or rat α7 nicotinic acetylcholine receptors that are about 60% of the maximal acetylcholine response. BMS-902483 improved 24h novel object recognition memory in mice with a minimal effective dose (MED) of 0.1mg/kg and reversed MK-801-induced deficits in a rat attentional set-shifting model of executive function with an MED of 3mg/kg. Enhancement of novel object recognition was blocked by the silent α7 nicotinic acetylcholine receptor agonist, NS6740, demonstrating that activity of BMS-902483 was mediated by α7 nicotinic acetylcholine receptors. BMS-902483 also reversed ketamine-induced deficits in auditory gating in rats, and enhanced ex vivo hippocampal long-term potentiation examined 24h after dosing in mice. Results from an ex vivo brain homogenate binding assay showed that α7 receptor occupancy ranged from 64% (novel object recognition) to ~90% (set shift and gating) at the MED for behavioral and sensory processing effects of BMS-902483. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Regulation of ventilation and oxygen consumption by delta- and mu-opioid receptor agonists.

    Science.gov (United States)

    Schaeffer, J I; Haddad, G G

    1985-09-01

    To study the effect of endorphins on metabolic rate and on the relationship between O2 consumption (VO2) and ventilation, we administered enkephalin analogues (relatively selective delta-receptor agonists) and a morphiceptin analogue (a highly selective mu-receptor agonist) intracisternally in nine unanesthetized chronically instrumented adult dogs. Both delta- and mu-agonists decreased VO2 by 40-60%. delta-Agonists induced a dose-dependent decrease in mean instantaneous minute ventilation (VT/TT) associated with periodic breathing. The decrease in VT/TT started and resolved prior to the decrease and returned to baseline of VO2, respectively. In contrast, the mu-agonists induced an increase in VT/TT associated with rapid shallow breathing. Arterial PCO2 increased and arterial PO2 decreased after both delta- and mu-agonists. Low doses of intracisternal naloxone (0.002-2.0 micrograms/kg) reversed the opioid effect on VT/TT but not on VO2; higher doses of naloxone (5-25 micrograms/kg) reversed both. Naloxone administered alone had no effect on VT/TT or VO2. These data suggest that 1) both delta- and mu-agonists induce alveolar hypoventilation despite a decrease in VO2, 2) this hypoventilation results from a decrease in VT/TT after delta-agonists but an increase in dead space ventilation after mu-agonists, and 3) endorphins do not modulate ventilation and metabolic rate tonically, but we speculate that they may do so in response to stressful stimulation.

  9. [The receptorial responsiveness method (RRM): a new possibility to estimate the concentration of pharmacologic agonists at their receptors].

    Science.gov (United States)

    Pák, Krisztián; Kiss, Zsuzsanna; Erdei, Tamás; Képes, Zita; Gesztelyi, Rudolf

    2014-01-01

    Cardiovascular disease is the biggest challenge in terms of life expectancy in developed countries. Adenosine contributes to the adaptation of the heart to ischemia and hypoxia, because adenosine, in addition to its metabolite role in the nucleic acid metabolism, is the endogenous agonist of the ubiquitous adenosine receptor family. Adenosine receptor activation is beneficial in most cases, it improves the balance between energy supply and consumption, reduces injury caused by stressors and inhibits the unfavorable tissue remodeling. Pharmacological manipulation of cardioprotective effects evoked by adenosine is an important, although to date not sufficiently utilized endeavor that may have therapeutic and preventive implications in cardiovascular diseases. As the ligand binding site of adenosine receptors is accessible from the extracellular space, it is especially important to know the adenosine concentration of the interstitial fluid ([Ado](ISF)). However, in the functioning heart, [Ado](ISF) values range in an extremely wide interval, spanning from nano- to micromolar concentrations, as estimated by the commonly used methods. Our recently developed procedure, the receptorial responsiveness method (RRM), may resolve this problem in certain cases. RRM enables quantification of an acute increase in the concentration of a pharmacological agonist, uniquely in the microenvironment of the receptors of the given agonist. As a limitation, concentration of agonists with short half-life (just like adenosine) at their receptors can only be quantified with the equieffective concentration of a stable agonist exerting the same action. In a previous study using RRM, inhibition of the transmembrane nucleoside transport in the euthyroid guinea pig atrium produced an increase in [Ado](ISF) that was equieffective with 18.8 +/- 3 nM CPA (N6-cyclopentyladenosine, a stable, selective A1 adenosine receptor agonist). This finding is consistent with observations of others, i.e., in the

  10. Identification of benzothiazole derivatives and polycyclic aromatic hydrocarbons as aryl hydrocarbon receptor agonists present in tire extracts.

    Science.gov (United States)

    He, Guochun; Zhao, Bin; Denison, Michael S

    2011-08-01

    Leachate from rubber tire material contains a complex mixture of chemicals previously shown to produce toxic and biological effects in aquatic organisms. The ability of these leachates to induce Ah receptor (AhR)-dependent cytochrome P4501A1 expression in fish indicated the presence of AhR active chemicals, but the responsible chemicals and their direct interaction with the AhR signaling pathway were not examined. Using a combination of AhR-based bioassays, we have demonstrated the ability of tire extract to stimulate both AhR DNA binding and AhR-dependent gene expression and confirmed that the responsible chemicals were metabolically labile. The application of CALUX (chemical-activated luciferase gene expression) cell bioassay-driven toxicant identification evaluation not only revealed that tire extract contained a variety of known AhR-active polycyclic aromatic hydrocarbons but also identified 2-methylthiobenzothiazole and 2-mercaptobenzothiazole as AhR agonists. Analysis of a structurally diverse series of benzothiazoles identified many that could directly stimulate AhR DNA binding and transiently activate the AhR signaling pathway and identified benzothiazoles as a new class of AhR agonists. In addition to these compounds, the relatively high AhR agonist activity of a large number of fractions strongly suggests that tire extract contains a large number of physiochemically diverse AhR agonists whose identities and toxicological/biological significances are unknown. Copyright © 2011 SETAC.

  11. Novel GLP-1 fusion chimera as potent long acting GLP-1 receptor agonist.

    Directory of Open Access Journals (Sweden)

    Qinghua Wang

    2010-09-01

    Full Text Available GLP-1 has a variety of anti-diabetic effects. However, native GLP-1 is not suitable for therapy of diabetes due to its short half-life (t1/2168 h. Intraperitoneal glucose tolerance test (IPGTT in mice showed that GLP-1/hIgG2 significantly decreased glucose excursion. Furthermore, IPGTT performed on mice one week after a single drug-injection also displayed significantly reduced glucose excursion, indicating that GLP-1/hIgG2 fusion protein has long-lasting effects on the modulation of glucose homeostasis. GLP-1/hIgG2 was found to be effective in reducing the incidence of diabetes in multiple-low-dose streptozotocin-induced type 1 diabetes in mice. Together, the long-lasting bioactive GLP-1/hIgG2 retains native GLP-1 activities and thus may serve as a potent GLP-1 receptor agonist.

  12. Angiotensin II Type 2 Receptor Agonist Experts Sustained Neuroprotective Effects In Aged Rats

    DEFF Research Database (Denmark)

    Sumners, Colin; Isenberg, Jacob; Harmel, Allison

    2016-01-01

    OBJECTIVE: The renin angiotensin system is a promising target for stroke neuroprotection and therapy through activation of angiotensin type II receptors (AT2R). The selective non-peptide AT2R agonist, Compound 21 (C21), has been shown to exhibit neuroprotection and improve stroke outcomes...... in preclinical studies, effects that likely involve neurotropic actions. However, these beneficial actions of C21 have not been demonstrated to occur beyond 1 week post stroke. The objective of this study was to determine if systemic administration of C21 would exert sustained neuroprotective effects in aged...... min), 24 h, and 48 h after stroke. Infarct size was assessed by magnetic resonance imaging at 21 days post MCAO. Animals received blinded neurological exams at 4 h, 24 h, 72 h, 7d, 14d, and 21d post-MCAO. RESULTS: Systemic treatment with C21 after stroke significantly improved neurological function...

  13. A key agonist-induced conformational change in the cannabinoid receptor CB1 is blocked by the allosteric ligand Org 27569.

    Science.gov (United States)

    Fay, Jonathan F; Farrens, David L

    2012-09-28

    Allosteric ligands that modulate how G protein-coupled receptors respond to traditional orthosteric drugs are an exciting and rapidly expanding field of pharmacology. An allosteric ligand for the cannabinoid receptor CB1, Org 27569, exhibits an intriguing effect; it increases agonist binding, yet blocks agonist-induced CB1 signaling. Here we explored the mechanism behind this behavior, using a site-directed fluorescence labeling approach. Our results show that Org 27569 blocks conformational changes in CB1 that accompany G protein binding and/or activation, and thus inhibit formation of a fully active CB1 structure. The underlying mechanism behind this behavior is that simultaneous binding of Org 27569 produces a unique agonist-bound conformation, one that may resemble an intermediate structure formed on the pathway to full receptor activation.

  14. Novel 5-HT6 receptor antagonists/D2 receptor partial agonists targeting behavioral and psychological symptoms of dementia.

    Science.gov (United States)

    Kołaczkowski, Marcin; Marcinkowska, Monika; Bucki, Adam; Śniecikowska, Joanna; Pawłowski, Maciej; Kazek, Grzegorz; Siwek, Agata; Jastrzębska-Więsek, Magdalena; Partyka, Anna; Wasik, Anna; Wesołowska, Anna; Mierzejewski, Paweł; Bienkowski, Przemyslaw

    2015-03-06

    We describe a novel class of designed multiple ligands (DMLs) combining serotonin 5-HT6 receptor (5-HT6R) antagonism with dopamine D2 receptor (D2R) partial agonism. Prototype hybrid molecules were designed using docking to receptor homology models. Diverse pharmacophore moieties yielded 3 series of hybrids with varying in vitro properties at 5-HT6R and D2R, and at M1 receptor and hERG channel antitargets. 4-(piperazin-1-yl)-1H-indole derivatives showed highest antagonist potency at 5-HT6R, with 7-butoxy-3,4-dihydroquinolin-2(1H)-one and 2-propoxybenzamide derivatives having promising D2R partial agonism. 2-(3-(4-(1-(phenylsulfonyl)-1H-indol-4-yl)piperazin-1-yl)propoxy)benzamide (47) exhibited nanomolar affinity at both 5-HT6R and D2R and was evaluated in rat models. It displayed potent antidepressant-like and anxiolytic-like activity in the Porsolt and Vogel tests, respectively, more pronounced than that of a reference selective 5-HT6R antagonist or D2R partial agonist. In addition, 47 also showed antidepressant-like activity (Porsolt's test) and anxiolytic-like activity (open field test) in aged (>18-month old) rats. In operant conditioning tests, 47 enhanced responding for sweet reward in the saccharin self-administration test, consistent with anti-anhedonic properties. Further, 47 facilitated extinction of non-reinforced responding for sweet reward, suggesting potential procognitive activity. Taken together, these studies suggest that DMLs combining 5-HT6R antagonism and D2R partial agonism may successfully target affective disorders in patients from different age groups without a risk of cognitive deficits. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  15. Effects of cannabinoid and vanilloid receptor agonists and their interaction on learning and memory in rats.

    Science.gov (United States)

    Shiri, Mariam; Komaki, Alireza; Oryan, Shahrbanoo; Taheri, Masoumeh; Komaki, Hamidreza; Etaee, Farshid

    2017-04-01

    Despite previous findings on the effects of cannabinoid and vanilloid systems on learning and memory, the effects of the combined stimulation of these 2 systems on learning and memory have not been studied. Therefore, in this study, we tested the interactive effects of cannabinoid and vanilloid systems on learning and memory in rats by using passive avoidance learning (PAL) tests. Forty male Wistar rats were divided into the following 4 groups: (1) control (DMSO+saline), (2) WIN55,212-2, (3) capsaicin, and (4) WIN55,212-2 + capsaicin. On test day, capsaicin, a vanilloid receptor type 1 (TRPV1) agonist, or WIN55,212-2, a cannabinoid receptor (CB 1 /CB 2 ) agonist, or both substances were injected intraperitoneally. Compared to the control group, the group treated with capsaicin (TRPV1 agonist) had better scores in the PAL acquisition and retention test, whereas treatment with WIN55,212-2 (CB 1 /CB 2 agonist) decreased the test scores. Capsaicin partly reduced the effects of WIN55,212-2 on PAL and memory. We conclude that the acute administration of a TRPV1 agonist improves the rats' cognitive performance in PAL tasks and that a vanilloid-related mechanism may underlie the agonistic effect of WIN55,212-2 on learning and memory.

  16. Synthesis and evaluation of 18F-labeled 5-HT2A receptor agonists as PET ligands

    DEFF Research Database (Denmark)

    Herth, Matthias M; Petersen, Ida Nymann; Hansen, Hanne Demant

    2016-01-01

    INTRODUCTION: The serotonin 2A receptor (5-HT2AR) is the most abundant excitatory 5-HT receptor in the human brain and implicated in various brain disorders such as schizophrenia, depression, and Alzheimer's disease. Positron emission tomography (PET) can be used to image specific proteins...... to be potent 5-HT2A agonists. (18)F-labeling of the appropriate precursors was performed using [(18)F]FETos, typically yielding 0.2-2.0GBq and specific activities of 40-120GBq/μmol. PET studies in Danish landrace pigs revealed that [(18)F]1 displayed brain uptake in 5-HT2AR rich regions. However, high uptake...

  17. Discovery and cardioprotective effects of the first non-Peptide agonists of the G protein-coupled prokineticin receptor-1.

    Directory of Open Access Journals (Sweden)

    Adeline Gasser

    Full Text Available Prokineticins are angiogenic hormones that activate two G protein-coupled receptors: PKR1 and PKR2. PKR1 has emerged as a critical mediator of cardiovascular homeostasis and cardioprotection. Identification of non-peptide PKR1 agonists that contribute to myocardial repair and collateral vessel growth hold promises for treatment of heart diseases. Through a combination of in silico studies, medicinal chemistry, and pharmacological profiling approaches, we designed, synthesized, and characterized the first PKR1 agonists, demonstrating their cardioprotective activity against myocardial infarction (MI in mice. Based on high throughput docking protocol, 250,000 compounds were computationally screened for putative PKR1 agonistic activity, using a homology model, and 10 virtual hits were pharmacologically evaluated. One hit internalizes PKR1, increases calcium release and activates ERK and Akt kinases. Among the 30 derivatives of the hit compound, the most potent derivative, IS20, was confirmed for its selectivity and specificity through genetic gain- and loss-of-function of PKR1. Importantly, IS20 prevented cardiac lesion formation and improved cardiac function after MI in mice, promoting proliferation of cardiac progenitor cells and neovasculogenesis. The preclinical investigation of the first PKR1 agonists provides a novel approach to promote cardiac neovasculogenesis after MI.

  18. In Vivo Protection against Strychnine Toxicity in Mice by the Glycine Receptor Agonist Ivermectin

    Directory of Open Access Journals (Sweden)

    Ahmed Maher

    2014-01-01

    Full Text Available The inhibitory glycine receptor, a ligand-gated ion channel that mediates fast synaptic inhibition in mammalian spinal cord and brainstem, is potently and selectively inhibited by the alkaloid strychnine. The anthelminthic and anticonvulsant ivermectin is a strychnine-independent agonist of spinal glycine receptors. Here we show that ivermectin is an effective antidote of strychnine toxicity in vivo and determine time course and extent of ivermectin protection. Mice received doses of 1 mg/kg and 5 mg/kg ivermectin orally or intraperitoneally, followed by an intraperitoneal strychnine challenge (2 mg/kg. Ivermectin, through both routes of application, protected mice against strychnine toxicity. Maximum protection was observed 14 hours after ivermectin administration. Combining intraperitoneal and oral dosage of ivermectin further improved protection, resulting in survival rates of up to 80% of animals and a significant delay of strychnine effects in up to 100% of tested animals. Strychnine action developed within minutes, much faster than ivermectin, which acted on a time scale of hours. The data agree with a two-compartment distribution of ivermectin, with fat deposits acting as storage compartment. The data demonstrate that toxic effects of strychnine in mice can be prevented if a basal level of glycinergic signalling is maintained through receptor activation by ivermectin.

  19. A monoclonal antibody TrkB receptor agonist as a potential therapeutic for Huntington's disease.

    Directory of Open Access Journals (Sweden)

    Daniel Todd

    Full Text Available Huntington's disease (HD is a devastating, genetic neurodegenerative disease caused by a tri-nucleotide expansion in exon 1 of the huntingtin gene. HD is clinically characterized by chorea, emotional and psychiatric disturbances and cognitive deficits with later symptoms including rigidity and dementia. Pathologically, the cortico-striatal pathway is severely dysfunctional as reflected by striatal and cortical atrophy in late-stage disease. Brain-derived neurotrophic factor (BDNF is a neuroprotective, secreted protein that binds with high affinity to the extracellular domain of the tropomyosin-receptor kinase B (TrkB receptor promoting neuronal cell survival by activating the receptor and down-stream signaling proteins. Reduced cortical BDNF production and transport to the striatum have been implicated in HD pathogenesis; the ability to enhance TrkB signaling using a BDNF mimetic might be beneficial in disease progression, so we explored this as a therapeutic strategy for HD. Using recombinant and native assay formats, we report here the evaluation of TrkB antibodies and a panel of reported small molecule TrkB agonists, and identify the best candidate, from those tested, for in vivo proof of concept studies in transgenic HD models.

  20. (-)-N-[(11)C]propyl-norapomorphine: a positron-labeled dopamine agonist for PET imaging of D(2) receptors.

    Science.gov (United States)

    Hwang, D R; Kegeles, L S; Laruelle, M

    2000-08-01

    Imaging neuroreceptors with radiolabeled agonists might provide valuable information on the in vivo agonist affinity states of receptors of interest. We report here the radiosynthesis, biodistribution in rodents, and imaging studies in baboons of [(11)C]-labeled (-)-N-propyl-norapomorphine [(-)-NPA]. (-)-[(11)C]NPA was prepared by reacting norapomorphine with [(11)C]propionyl chloride and a lithium aluminum hydride reduction. [(11)C]Propionyl chloride was prepared by reacting [(11)C]CO(2) with ethylmagnesium bromide, followed by reacting with phthaloyl chloride. The radiochemical yield of (-)-[(11)C]NPA was 2.5% at end of synthesis (EOS), and the synthesis time was 60 min. The specific activity was 1700+/-1900 mCi/micromol ( N=7; ranged 110-5200 mCi/micromol at EOS). Rodent biodistribution studies showed high uptake of [(11)C](-)-NPA in D(2) receptor-rich areas, and the striatum/cerebellum ratios were 1.7, 3.4, and 4.4 at 5 min, 30 min, and 60 min postinjection, respectively. Pretreating the animals with haloperidol (1 mg/kg) decreased the striatum/cerebellum ratio at 30 min postinjection to 1.3. (-)-[(11)C]NPA was also evaluated via baboon positron emission tomography (PET) studies. Under control conditions ( N=4), rapid uptake of the tracer was observed and the striatum/cerebellum ratio reached 2.86+/-0.15 at 45 min postinjection. Following haloperidol pretreatment (0.2 mg/kg IV), the striatum/cerebellum ratio was 1.29 at 45 min postinjection. The result demonstrated the existence of specific binding of this new tracer to the D(2) receptor. To our knowledge, the current finding of a striatum/cerebellum ratio of 2.8 in baboon was the highest reported with a radiolabeled D(2) agonist. (-)-[(11)C]NPA is a promising new D(2) agonist PET tracer for probing D(2) receptors in vivo using PET.

  1. Pharmacological Characterization of 30 Human Melanocortin-4 Receptor Polymorphisms with the Endogenous Proopiomelanocortin Derived Agonists, Synthetic Agonists, and the Endogenous Agouti-Related Protein (AGRP) Antagonist

    Science.gov (United States)

    Xiang, Zhimin; Proneth, Bettina; Dirain, Marvin L.; Litherland, Sally A.; Haskell-Luevano, Carrie

    2010-01-01

    The melanocortin-4 receptor (MC4R) is a G-protein coupled receptor (GPCR) that is expressed in the central nervous system and has a role in regulating feeding behavior, obesity, energy homeostasis, male erectile response, and blood pressure. Since the report of the MC4R knockout mouse in 1997, the field has been searching for links between this genetic bio marker and human obesity and type 2 diabetes. More then 80 single nucleotide polymorphisms (SNPs) have been identified from human patients, both obese and non-obese controls. Many significant studies have been performed examining the pharmacological characteristics of these hMC4R SNPs in attempts to identify a molecular defects/insights that might link a genetic factor to the obese phenotype observed in patients possessing these mutations. Our laboratory has previously reported the pharmacological characterization of 40 of these polymorphic hMC4 receptors with multiple endogenous and synthetic ligands. The goal of the current study is to perform a similar comprehensive side-by-side characterization of 30 additional human hMC4R with single nucleotide polymorphisms using multiple endogenous agonists [α-, β, γ2-melanocyte stimulating hormones (MSH) and adrenocorticotropin (ACTH)], the antagonist agouti-related protein hAGRP(87-132), and synthetic agonists [NDP-MSH, MTII, and the tetrapeptide Ac-His-DPhe-Arg-Trp-NH2 (JRH887-9)]. These in vitro data, in some cases, provide a putative molecular link between dysfunctional hMC4R's and human obesity. These 30 hMC4R SNPs include R7H, R18H, R18L, S36Y, P48S, V50M, F51L, E61K, I69T, D90N, S94R, G98R, I121T, A154D, Y157S, W174C, G181D, F202L, A219V, I226T, G231S, G238D, N240S, C271R, S295P, P299L, E308K, I317V, L325F and 750DelGA. All but the N240S hMC4R were identified in obese patients. Additionally, we have characterized a double I102T/V103I hMC4R. In addition to the pharmacological characterization, the hMC4R variants were evaluated for cell surface expression by flow

  2. Pharmacological characterization of 30 human melanocortin-4 receptor polymorphisms with the endogenous proopiomelanocortin-derived agonists, synthetic agonists, and the endogenous agouti-related protein antagonist.

    Science.gov (United States)

    Xiang, Zhimin; Proneth, Bettina; Dirain, Marvin L; Litherland, Sally A; Haskell-Luevano, Carrie

    2010-06-08

    The melanocortin-4 receptor (MC4R) is a G-protein-coupled receptor (GPCR) that is expressed in the central nervous system and has a role in regulating feeding behavior, obesity, energy homeostasis, male erectile response, and blood pressure. Since the report of the MC4R knockout mouse in 1997, the field has been searching for links between this genetic biomarker and human obesity and type 2 diabetes. More then 80 single nucleotide polymorphisms (SNPs) have been identified from human patients, both obese and nonobese controls. Many significant studies have been performed examining the pharmacological characteristics of these hMC4R SNPs in attempts to identify a molecular defects/insights that might link a genetic factor to the obese phenotype observed in patients possessing these mutations. Our laboratory has previously reported the pharmacological characterization of 40 of these polymorphic hMC4 receptors with multiple endogenous and synthetic ligands. The goal of the current study is to perform a similar comprehensive side-by-side characterization of 30 additional human hMC4R with single nucleotide polymorphisms using multiple endogenous agonists [alpha-, beta-, and gamma(2)-melanocyte stimulating hormones (MSH) and adrenocorticotropin (ACTH)], the antagonist agouti-related protein hAGRP(87-132), and synthetic agonists [NDP-MSH, MTII, and the tetrapeptide Ac-His-dPhe-Arg-Trp-NH(2) (JRH887-9)]. These in vitro data, in some cases, provide a putative molecular link between dysfunctional hMC4R's and human obesity. These 30 hMC4R SNPs include R7H, R18H, R18L, S36Y, P48S, V50M, F51L, E61K, I69T, D90N, S94R, G98R, I121T, A154D, Y157S, W174C, G181D, F202L, A219 V, I226T, G231S, G238D, N240S, C271R, S295P, P299L, E308K, I317V, L325F, and 750DelGA. All but the N240S hMC4R were identified in obese patients. Additionally, we have characterized a double I102T/V103I hMC4R. In addition to the pharmacological characterization, the hMC4R variants were evaluated for cell surface

  3. Differential effects of a selective dopamine D1-like receptor agonist on motor activity and c-fos expression in the frontal-striatal circuitry of SHR and Wistar-Kyoto rats

    Directory of Open Access Journals (Sweden)

    Diaz Heijtz Rochellys

    2006-05-01

    Full Text Available Abstract Background Molecular genetic studies suggest the dopamine D1 receptor (D1R may be implicated in attention-deficit/hyperactivity disorder (ADHD. As little is known about the potential motor role of D1R in ADHD, animal models may provide important insights into this issue. Methods We investigated the effects of a full and selective D1R agonist, SKF-81297 (0.3, 3 and 10 mg/kg, on motor behaviour and expression of the plasticity-associated gene, c-fos, in habituated young adult male Spontaneously Hypertensive Rats (SHR, the most commonly used animal model of ADHD, and Wistar-Kyoto (WKY; the strain from which SHR were derived. Results SHR rats were more behaviourally active than WKY rats after injection with vehicle. The 0.3 mg/kg dose of SKF-81297 increased motor behaviour (locomotion, sifting, rearing, and sniffing in both SHR and WKY rats. Total grooming was also stimulated, but only in WKY rats. The same dose increased c-fos mRNA expression in the piriform cortex of both strains. The 3 mg/kg dose increased sifting and sniffing in both strains. Locomotion was also stimulated towards the end of the testing period. The intermediate dose decreased total rearing in both strains, and produced a significant increase in c-fos mRNA in the striatum, nucleus accumbens, olfactory tuberculum, and in the cingulate, agranular insular and piriform cortices. The 10 mg/kg dose of SKF-81297 produced a biphasic effect on locomotion, which was characterized by an initial decrease followed by later stimulation. The latter stimulatory effect was more pronounced in SHR than in WKY rats when compared to their respective vehicle-injected groups. The 10 mg/kg dose also stimulated sifting and sniffing in both strains. Both the 3 and 10 mg/kg doses had no effect on total grooming. The 10 mg/kg dose induced significantly higher levels of c-fos mRNA expression in the nucleus accumbens and adjacent cortical regions (but not striatum of SHR when compared to WKY rats

  4. Serotonin(4) (5-HT(4)) receptor agonists are putative antidepressants with a rapid onset of action

    DEFF Research Database (Denmark)

    Lucas, Guillaume; Rymar, Vladimir V; Du, Jenny

    2007-01-01

    parameters considered to be key markers of antidepressant action, but that are observed only after 2-3 week treatments with classical molecules: desensitization of 5-HT(1A) autoreceptors, increased tonus on hippocampal postsynaptic 5-HT(1A) receptors, and enhanced phosphorylation of the CREB protein...... intake consecutive to a chronic mild stress. These findings point out 5-HT(4) receptor agonists as a putative class of antidepressants with a rapid onset of action. Udgivelsesdato: 2007-Sep-6...

  5. Design and Discovery of Functionally Selective Serotonin 2C (5-HT2C) Receptor Agonists.

    Science.gov (United States)

    Cheng, Jianjun; McCorvy, John D; Giguere, Patrick M; Zhu, Hu; Kenakin, Terry; Roth, Bryan L; Kozikowski, Alan P

    2016-11-10

    On the basis of the structural similarity of our previous 5-HT 2C agonists with the melatonin receptor agonist tasimelteon and the putative biological cross-talk between serotonergic and melatonergic systems, a series of new (2,3-dihydro)benzofuran-based compounds were designed and synthesized. The compounds were evaluated for their selectivity toward 5-HT 2A , 5-HT 2B , and 5-HT 2C receptors in the calcium flux assay with the ultimate goal to generate selective 5-HT 2C agonists. Selected compounds were studied for their functional selectivity by comparing their transduction efficiency at the G protein signaling pathway versus β-arrestin recruitment. The most functionally selective compound (+)-7e produced weak β-arrestin recruitment and also demonstrated less receptor desensitization compared to serotonin in both calcium flux and phosphoinositide (PI) hydrolysis assays. We report for the first time that selective 5-HT 2C agonists possessing weak β-arrestin recruitment can produce distinct receptor desensitization properties.

  6. Intersubunit bridge formation governs agonist efficacy at nicotinic acetylcholine alpha4beta2 receptors

    DEFF Research Database (Denmark)

    Rohde, Line Aagot Hede; Ahring, Philip Kiær; Jensen, Marianne Lerbech

    2012-01-01

    The a4ß2 subtype of the nicotinic acetylcholine receptor (nAChR) has been pursued as a drug target for treatment of psychiatric and neurodegenerative disorders and smoking cessation aids for decades. Still, a thorough understanding of structure-function relationships of a4ß2 agonists is lacking...

  7. Therapeutic efficacy of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) against organophosphate intoxication

    NARCIS (Netherlands)

    Bueters, T.J.H.; Groen, B.; Danhof, M.; IJzerman, A.P.; Helden, H.P.M. van

    2002-01-01

    The objective of the present study was to investigate whether reduction of central acetylcholine (ACh) accumulation by adenosine receptor agonists could serve as a generic treatment against organophosphate (OP) poisoning. The OPs studied were tabun (O-ethyl-N-dimethylphosphoramidocyanidate), sarin

  8. Novel non-indolic melatonin receptor agonists differentially entrain endogenous melatonin rhythm and increase its amplitude

    NARCIS (Netherlands)

    Drijfhout, W.J; de Vries, J.B; Homan, E.J; Brons, H.F; Copinga, S; Gruppen, G; Beresford, I.J M; Hagan, R.M; Grol, Cor; Westerink, B.H.C.

    1999-01-01

    In this study we have examined the ability of melatonin and four synthetic melatonin receptor agonists to entrain endogenous melatonin secretion in rats, free running in constant darkness. The circadian melatonin profile was measured by trans-pineal microdialysis, which not only reveals the time of

  9. Differential Effects of Cannabinoid Receptor Agonist on Social Discrimination and Contextual Fear in Amygdala and Hippocampus

    Science.gov (United States)

    Segev, Amir; Akirav, Irit

    2011-01-01

    We examined whether the cannabinoid receptor agonist WIN55,212-2 (WIN; 5 [mu]g/side) microinjected into the hippocampus or the amygdala would differentially affect memory processes in a neutral vs. an aversive task. In the aversive contextual fear task, WIN into the basolateral amygdala impaired fear acquisition/consolidation, but not retrieval.…

  10. The angiotensin type 2 receptor agonist Compound 21 elicits cerebroprotection in endothelin-1 induced ischemic stroke

    DEFF Research Database (Denmark)

    Joseph, Jason P; Mecca, Adam P; Regenhardt, Robert W

    2014-01-01

    Evidence indicates that angiotensin II type 2 receptors (AT2R) exert cerebroprotective actions during stroke. A selective non-peptide AT2R agonist, Compound 21 (C21), has been shown to exert beneficial effects in models of cardiac and renal disease, as well as hemorrhagic stroke. Here, we hypothe...

  11. G-protein mediates voltage regulation of agonist binding to muscarinic receptors: effects on receptor-Na+ channel interaction

    International Nuclear Information System (INIS)

    Cohen-Armon, M.; Garty, H.; Sokolovsky, M.

    1988-01-01

    The authors previous experiments in membranes prepared from rat heart and brain led them to suggest that the binding of agonist to the muscarinic receptors and to the Na + channels is a coupled event mediated by guanine nucleotide binding protein(s) [G-protein(s)]. These in vitro findings prompted us to employ synaptoneurosomes from brain stem tissue to examine (i) the binding properties of [ 3 H] acetylcholine at resting potential and under depolarization conditions in the absence and presence of pertussis toxin; (ii) the binding of [ 3 H]batrachotoxin to Na + channel(s) in the presence of the muscarinic agonists; and (iii) muscarinically induced 22 Na + uptake in the presence and absence of tetrodotoxin, which blocks Na + channels. The findings indicate that agonist binding to muscarinic receptors is voltage dependent, that this process is mediated by G-protein(s), and that muscarinic agonists induce opening of Na + channels. The latter process persists even after pertussis toxin treatment, indicating that it is not likely to be mediated by pertussis toxin sensitive G-protein(s). The system with its three interacting components-receptor, G-protein, and Na + channel-is such that at resting potential the muscarinic receptor induces opening of Na + channels; this property may provide a possible physiological mechanism for the depolarization stimulus necessary for autoexcitation or repetitive firing in heart or brain tissues

  12. Effects of the potential 5-HT7 receptor agonist AS 19 in an autoshaping learning task.

    Science.gov (United States)

    Perez-García, Georgina S; Meneses, A

    2005-08-30

    This work aimed to evaluate further the role of 5-HT7 receptors during memory formation in an autoshaping Pavlovian/instrumental learning task. Post-training administration of the potential 5-HT7 receptor agonist AS 19 or antagonist SB-269970 enhanced memory formation or had no effect, respectively. The AS 19 facilitatory effect was reversed by SB-269970, but not by the selective 5-HT1A antagonist WAY100635. Amnesia induced by scopolamine (cholinergic antagonist) or dizocilpine (NMDA antagonist) was also reversed by AS 19. Certainly, reservations regarding the selectivity of AS 19 for 5-HT7 and other 5-HT receptors in vivo are noteworthy and, therefore, its validity for use in animal models as a pharmacological tool. Having mentioned that, it should be noticed that together these data are providing further support to the notion of the 5-HT7 receptors role in memory formation. Importantly, this 5-HT7 receptor agonist AS 19 appears to represent a step forward respect to the notion that potent and selective 5-HT7 receptor agonists can be useful in the treatment of dysfunctional memory in aged-related decline and Alzheimer's disease.

  13. Inhibition of receptor tyrosine kinase signalling by small molecule agonist of T-cell protein tyrosine phosphatase

    International Nuclear Information System (INIS)

    Mattila, Elina; Marttila, Heidi; Sahlberg, Niko; Kohonen, Pekka; Tähtinen, Siri; Halonen, Pasi; Perälä, Merja; Ivaska, Johanna

    2010-01-01

    T-cell protein tyrosine phosphatase (TCPTP/TC45) is a ubiquitously expressed intra-cellular non-receptor protein tyrosine phosphatase involved in the negative regulation of several cancer relevant cellular signalling pathways. We have previously shown that interaction between the α-cytoplasmic tail of α1β1 integrin and TCPTP activates TCPTP by disrupting an inhibitory intra-molecular bond in TCPTP. Thus, inhibition of the regulatory interaction in TCPTP is a desirable strategy for TCPTP activation and attenuation of oncogenic RTK signalling. However, this is challenging with low molecular weight compounds. We developed a high-throughput compatible assay to analyse activity of recombinant TCPTP in vitro. Using this assay we have screened 64280 small molecules to identify novel agonists for TCPTP. Dose-dependent response to TCPTP agonist was performed using the in vitro assay. Inhibition effects and specificity of TCPTP agonists were evaluated using TCPTP expressing and null mouse embryonic fibroblasts. Western blot analysis was used to evaluate attenuation of PDGFRβ and EGFR phosphorylation. Inhibition of VEGF signalling was analysed with VEGF-induced endothelial cell sprouting assays. From the screen we identified six TCPTP agonists. Two compounds competed with α1-cytoplasmic domain for binding to TCPTP, suggesting that they activate TCPTP similar to α1-cyt by disrupting the intra-molecular bond in TCPTP. Importantly, one of the compounds (spermidine) displayed specificity towards TCPTP in cells, since TCPTP -/- cells were 43-fold more resistant to the compound than TCPTP expressing cells. This compound attenuates PDGFRβ and VEGFR2 signalling in cells in a TCPTP-dependent manner and functions as a negative regulator of EGFR phosphorylation in cancer cells. In this study we showed that small molecules mimicking TCPTP-α1 interaction can be used as TCPTP agonists. These data provide the first proof-of-concept description of the use of high-throughput screening

  14. Structural basis for constitutive activity and agonist-induced activation of the enteroendocrine fat sensor GPR119

    DEFF Research Database (Denmark)

    Engelstoft, Maja Storm; Norn, C; Pedersen, Maria Hauge

    2014-01-01

    BACKGROUND AND PURPOSE: GPR119 is a Gαs-coupled 7TM receptor activated by endogenous lipids such as oleoylethanolamide (OEA) and by the dietary triglyceride metabolite 2-monoacylglycerol. GPR119 stimulates enteroendocrine hormone and insulin secretion. But despite massive drug discovery efforts...... activation (AR231453 and OEA). Novel Rosetta-based receptor modelling was applied, using a composite template approach with segments from different X-ray structures and fully flexible ligand docking. KEY RESULTS: The increased signalling induced by increasing the cell surface expression of GPR119...... in the absence of agonist and the inhibitory effect of two synthetic inverse agonists demonstrated that GRP119 signals with a high degree of constitutive activity through the Gαs pathway. The mutational maps for AR231453 and OEA were very similar and, surprisingly, also similar to the mutational map for residues...

  15. Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors

    Energy Technology Data Exchange (ETDEWEB)

    Di Paolo, T.; Falardeau, P.

    1987-08-31

    The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p < 0.001). Competition for (/sup 3/H)-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-(..beta..-..gamma..-imino)triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables.

  16. Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors

    International Nuclear Information System (INIS)

    Di Paolo, T.; Falardeau, P.

    1987-01-01

    The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p 3 H]-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-[β-γ-imino]triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables

  17. Mechanisms of anorexia-cachexia syndrome and rational for treatment with selective ghrelin receptor agonist.

    Science.gov (United States)

    Esposito, Angela; Criscitiello, Carmen; Gelao, Lucia; Pravettoni, Gabriella; Locatelli, Marzia; Minchella, Ida; Di Leo, Maria; Liuzzi, Rita; Milani, Alessandra; Massaro, Mariangela; Curigliano, Giuseppe

    2015-11-01

    Cancer cachexia is a multi-organ, multifactorial and often irreversible syndrome affecting many patients with cancer. Cancer cachexia is invariably associated with weight loss, mainly from loss of skeletal muscle and body fat, conditioning a reduced quality of life due to asthenia, anorexia, anaemia and fatigue. Treatment options for treating cancer cachexia are limited. The approach is multimodal and may include: treatment of secondary gastrointestinal symptoms, nutritional treatments, drug, and non-drug treatments. Nutritional counselling and physical training may be beneficial in delaying or preventing the development of anorexia-cachexia. However, these interventions are limited in their effect, and no definitive pharmacological treatment is available to address the relevant components of the syndrome. Anamorelin is a first-in-class, orally active ghrelin receptor agonist that binds and stimulates the growth hormone secretagogue receptor centrally, thereby mimicking the appetite-enhancing and anabolic effects of ghrelin. It represents a new class of drug and an additional treatment option for this patient group, whose therapeutic options are currently limited. In this review we examine the mechanisms of anamorelin by which it contrasts catabolic states, its role in regulation of metabolism and energy homeostasis, the data of recent trials in the setting of cancer cachexia and its safety profile. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Lixisenatide, a novel GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Christensen, Mikkel; Knop, Filip K; Holst, Jens J

    2009-01-01

    Lixisenatide, under development by sanofi-aventis, is a novel human glucagon-like peptide-1 receptor (GLP-1R) agonist for the treatment of type 2 diabetes mellitus (T2DM; non-insulin dependent diabetes). The structure of lixisenatide, based on exendin-4(1-39) modified C-terminally with six Lys...... of the anticipated effects of lixisenatide on glycemic measures and weight; favorable results would place lixisenatide for consideration among other GLP-1R agonists in the treatment armamentarium for T2DM....

  19. Partial agonists and subunit selectivity at NMDA receptors

    DEFF Research Database (Denmark)

    Risgaard, Rune; Hansen, Kasper Bø; Clausen, Rasmus Prætorius

    2010-01-01

    Subunit-selective ligands for glutamate receptors remains an area of interest as glutamate is the major excitatory neurotransmitter in the brain and involved in a number of diseased states in the central nervous system (CNS). Few subtype-selective ligands are known, especially among the N...

  20. The role of adenosine receptor agonists in regulation of hematopoiesis

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Weiterová, Lenka; Hoferová, Zuzana

    2011-01-01

    Roč. 16, č. 1 (2011), s. 675-685 ISSN 1420-3049 R&D Projects: GA MO OVBIOFYZ20101; GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : adenosine receptors * hematopoiesis * myelosuppression Subject RIV: BO - Biophysics Impact factor: 2.386, year: 2011

  1. [18F]F15599, a novel 5-HT1A receptor agonist, as a radioligand for PET neuroimaging

    International Nuclear Information System (INIS)

    Lemoine, Laetitia; Verdurand, Mathieu; Vacher, Bernard; Blanc, Elodie; Newman-Tancredi, Adrian; Le Bars, Didier; Zimmer, Luc

    2010-01-01

    The serotonin-1A (5-HT 1A ) receptor is implicated in the pathophysiology of major neuropsychiatric disorders. Thus, the functional imaging of 5-HT 1A receptors by positron emission tomography (PET) may contribute to the understanding of its role in those pathologies and their therapeutics. These receptors exist in high- and low-affinity states and it is proposed that agonists bind preferentially to the high-affinity state of the receptor and therefore could provide a measure of the functional 5-HT 1A receptors. Since all clinical PET 5-HT 1A radiopharmaceuticals are antagonists, it is of great interest to develop a 18 F labelled agonist. F15599 (3-chloro-4-fluorophenyl-(4-fluoro-4{ [(5-methyl-pyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone) is a novel ligand with high affinity and selectivity for 5-HT 1A receptors and is currently tested as an antidepressant. In pharmacological tests in rat, it exhibits preferential agonist activity at post-synaptic 5-HT 1A receptors in cortical brain regions. Here, its nitro-precursor was synthesised and radiolabelled via a fluoronucleophilic substitution. Radiopharmacological evaluations included in vitro and ex vivo autoradiography in rat brain and PET scans on rats and cats. Results were compared with simultaneous studies using [ 18 F]MPPF, a validated 5-HT 1A antagonist radiopharmaceutical. The chemical and radiochemical purities of [ 18 F]F15599 were >98%. In vitro [ 18 F ]F15599 binding was consistent with the known 5-HT 1A receptors distribution (hippocampus, dorsal raphe nucleus, and notably cortical areas) and addition of Gpp(NH)p inhibited [ 18 F ]F15599 binding, consistent with a specific binding to G protein-coupled receptors. In vitro binding of [ 18 F]F15599 was blocked by WAY100635 and 8-OH-DPAT, respectively, prototypical 5-HT 1A antagonist and agonist. The ex vivo and in vivo studies demonstrated that the radiotracer readily entered the rat and the cat brain and generated few brain radioactive

  2. [18F]F15599, a novel 5-HT1A receptor agonist, as a radioligand for PET neuroimaging.

    Science.gov (United States)

    Lemoine, Laëtitia; Verdurand, Mathieu; Vacher, Bernard; Blanc, Elodie; Le Bars, Didier; Newman-Tancredi, Adrian; Zimmer, Luc

    2010-03-01

    The serotonin-1A (5-HT(1A)) receptor is implicated in the pathophysiology of major neuropsychiatric disorders. Thus, the functional imaging of 5-HT(1A) receptors by positron emission tomography (PET) may contribute to the understanding of its role in those pathologies and their therapeutics. These receptors exist in high- and low-affinity states and it is proposed that agonists bind preferentially to the high-affinity state of the receptor and therefore could provide a measure of the functional 5-HT(1A) receptors. Since all clinical PET 5-HT(1A) radiopharmaceuticals are antagonists, it is of great interest to develop a( 18)F labelled agonist. F15599 (3-chloro-4-fluorophenyl-(4-fluoro-4{[(5-methyl-pyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone) is a novel ligand with high affinity and selectivity for 5-HT(1A) receptors and is currently tested as an antidepressant. In pharmacological tests in rat, it exhibits preferential agonist activity at post-synaptic 5-HT(1A) receptors in cortical brain regions. Here, its nitro-precursor was synthesised and radiolabelled via a fluoronucleophilic substitution. Radiopharmacological evaluations included in vitro and ex vivo autoradiography in rat brain and PET scans on rats and cats. Results were compared with simultaneous studies using [(18)F]MPPF, a validated 5-HT(1A) antagonist radiopharmaceutical. The chemical and radiochemical purities of [(18)F]F15599 were >98%. In vitro [(18)F]F15599 binding was consistent with the known 5-HT(1A) receptors distribution (hippocampus, dorsal raphe nucleus, and notably cortical areas) and addition of Gpp(NH)p inhibited [(18)F]F15599 binding, consistent with a specific binding to G protein-coupled receptors. In vitro binding of [(18)F]F15599 was blocked by WAY100635 and 8-OH-DPAT, respectively, prototypical 5-HT(1A) antagonist and agonist. The ex vivo and in vivo studies demonstrated that the radiotracer readily entered the rat and the cat brain and generated few brain

  3. Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms.

    Science.gov (United States)

    Wang, Jingxian; Bernhöft, Silke; Pfister, Gerd; Schramm, Karl-Werner

    2014-10-15

    SPMD-based virtual organisms (VOs) were deployed at five to eight sites in the Three Gorges Reservoir (TGR), China for five periods in 2008, 2009 and 2011. The water exposure of aryl hydrocarbon receptor (AhR) agonists was assessed by the VOs. The chosen bioassay response for the extracts of the VOs, the induction of 7-ethoxyresorufin-O-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The results show that the extracts from the VOs could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) accounted for water level reached a maximum of 175 m. Although the aqueous concentration of AhR agonists of 0.8-4.8 pg TCDDL(-1) in TGR was not alarming, the tendency of accumulating high concentration of AhR agonists in VO lipid and existence of possible synergism or antagonism in the water may exhibit a potential hazard to local biota being exposed to AhR agonists. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Characterization of melanocortin NDP-MSH agonist peptide fragments at the mouse central and peripheral melanocortin receptors.

    Science.gov (United States)

    Haskell-Luevano, C; Holder, J R; Monck, E K; Bauzo, R M

    2001-06-21

    The central melanocortin receptors, melanocortin-4 (MC4R) and melanocortin-3 (MC3R), are involved in the regulation of satiety and energy homeostasis. The MC4R in particular has become a pharmaceutical industry drug target due to its direct involvement in the regulation of food intake and its potential therapeutic application for the treatment of obesity-related diseases. The melanocortin receptors are stimulated by the native ligand, alpha-melanocyte stimulating hormone (alpha-MSH). The potent and enzymatically stable analogue NDP-MSH (Ac-Ser-Tyr-Ser-Nle-Glu-His-DPhe-Arg-Trp-Gly-Lys-Pro-Val-NH(2)) is a lead peptide for the identification of melanocortin amino acids important for receptor molecular recognition and stimulation. We have synthesized nine peptide fragments of NDP-MSH, deleting N- and C-terminal amino acids to determine the "minimally active" sequence of NDP-MSH. Additionally, five peptides were synthesized to study stereochemical inversion at the Phe 7 and Trp 9 positions in attempts to increase tetra- and tripeptide potencies. These peptide analogues were pharmacologically characterized at the mouse melanocortin MC1, MC3, MC4, and MC5 receptors. This study has identified the Ac-His-DPhe-Arg-Trp-NH(2) tetrapeptide as possessing 10 nM agonist activity at the brain MC4R. The tripeptide Ac-DPhe-Arg-Trp-NH(2) possessed micromolar agonist activities at the MC1R, MC4R, and MC5R but only slight stimulatory activity was observed at the MC3R (at up to 100 microM concentration). This study has also examined to importance of both N- and C-terminal NDP-MSH amino acids at the different melanocortin receptors, providing information for drug design and identification of putative ligand-receptor interactions.

  5. Molecular sampling of the allosteric binding pocket of the TSH receptor provides discriminative pharmacophores for antagonist and agonists.

    Science.gov (United States)

    Hoyer, Inna; Haas, Ann-Karin; Kreuchwig, Annika; Schülein, Ralf; Krause, Gerd

    2013-02-01

    The TSHR (thyrotropin receptor) is activated endogenously by the large hormone thyrotropin and activated pathologically by auto-antibodies. Both activate and bind at the extracellular domain. Recently, SMLs (small-molecule ligands) have been identified, which bind in an allosteric binding pocket within the transmembrane domain. Modelling driven site-directed mutagenesis of amino acids lining this pocket led to the delineation of activation and inactivation sensitive residues. Modified residues showing CAMs (constitutively activating mutations) indicate signalling-sensitive positions and mark potential trigger points for agonists. Silencing mutations lead to an impairment of basal activity and mark contact points for antagonists. Mapping these residues on to a structural model of TSHR indicates locations where an SML may switch the receptor to an inactive or active conformation. In the present article, we report the effects of SMLs on these signalling-sensitive amino acids at the TSHR. Surprisingly, the antagonistic effect of SML compound 52 was reversed to an agonistic effect, when tested at the CAM Y667A. Switching agonism to antagonism and the reverse by changing either SMLs or residues covering the binding pocket provides detailed knowledge about discriminative pharmacophores. It prepares the basis for rational optimization of new high-affinity antagonists to interfere with the pathogenic activation of the TSHR.

  6. Metabolic rate in different rat brain areas during seizures induced by a specific delta opiate receptor agonist.

    Science.gov (United States)

    Haffmans, J; De Kloet, R; Dzoljic, M R

    1984-06-04

    The glucose utilization during specific delta opiate agonist-induced epileptiform phenomena, determined by the [14C]2-deoxyglucose technique (2-DG), was examined in various rat brain areas at different time intervals. The peak in EEG spiking response and the most intensive 2-DG uptake occurred 5 min after intraventricular (i.v.t.) administration of the delta opiate receptor agonist. The most pronounced 2-DG uptake at this time interval can be observed in the subiculum, including the CA1 hippocampal area, frontal cortex and central amygdala. A general decrease of glucose consumption, compared to control values, is observed after 10 min, in all regions, with exception of the subiculum. Since functional activity and 2-DG uptake are correlated, we suggest that the subiculum and/or CA1 area, are probably the brain regions most involved in the enkephalin-induced epileptic phenomena.

  7. In vitro and mouse in vivo characterization of the potent free fatty acid 1 receptor agonist TUG-469

    DEFF Research Database (Denmark)

    Urban, C; Hamacher, A; Partke, H J

    2013-01-01

    in vitro potency of TUG-469 compared to the reference FFA1 agonist GW9508 and to prove in vivo activity in a pre-diabetic mouse model. The in vitro pharmacology of TUG-469 was studied using Ca(2+)-, cAMP-, and impedance-based assays at recombinant FFA1 and free fatty acid receptor 4, formerly known as GPR......120 (FFA4) expressing 1321N1 cells and the rat insulinoma cell line INS-1. Furthermore, we investigated the systemic effect of TUG-469 on glucose tolerance in pre-diabetic New Zealand obese (NZO) mice performing a glucose tolerance test after intraperitoneal administration of 5 mg/kg TUG-469...... significantly improved glucose tolerance in pre-diabetic NZO mice. TUG-469 turned out as a promising candidate for further drug development of FFA1 agonists for treatment of type 2 diabetes mellitus....

  8. A combined α7 nicotinic acetylcholine receptor agonist and monoamine reuptake inhibitor, NS9775, represents a novel profile with potential benefits in emotional and cognitive disturbances

    DEFF Research Database (Denmark)

    Andreasen, Jesper T; Redrobe, John P; Nielsen, Elsebet Ø

    2013-01-01

    also improve by nicotinic acetylcholine receptor (nAChR) activation. Preclinical studies have corroborated this and also demonstrated a synergistic antidepressant-like action when nAChR agonists and MRIs are combined. Here, we present the in vitro and in vivo profile of NS9775, a combined full α7 n...

  9. X-ray structures of progesterone receptor ligand binding domain in its agonist state reveal differing mechanisms for mixed profiles of 11beta-substituted steroids.

    NARCIS (Netherlands)

    Lusher, S.J.; Raaijmakers, H.C.A.; Vu-Pham, D.; Kazemier, B.; Bosch, R.; McGuire, R.; Azevedo, R.; Hamersma, H.; Dechering, K.; Oubrie, A.; Duin, M. van; Vlieg, J. de

    2012-01-01

    We present here the x-ray structures of the progesterone receptor (PR) in complex with two mixed profile PR modulators whose functional activity results from two differing molecular mechanisms. The structure of Asoprisnil bound to the agonist state of PR demonstrates the contribution of the ligand

  10. The effects of acute multiple intraperitoneal injections of the GABAB receptor agonist baclofen on food intake in rats.

    Science.gov (United States)

    Patel, Sunit M; Ebenezer, Ivor S

    2008-12-28

    This study was undertaken to examine the effects of acute repeated administration of the GABA(B) receptor agonist baclofen on food intake in rats. In Experiment 1, the effects of repeated intraperitoneal (i.p.) injections of the GABA(B) receptor agonist baclofen (1 and 2 mg/kg) at 2 h intervals were investigated on food intake in non-deprived male Wistar rats. Both doses of baclofen significantly increased food intake after the 1st injection (PGABA(B) receptor agonists on food intake and energy homeostasis.

  11. Stereochemical studies of the monocyclic agouti-related protein (103-122) Arg-Phe-Phe residues: conversion of a melanocortin-4 receptor antagonist into an agonist and results in the discovery of a potent and selective melanocortin-1 agonist.

    Science.gov (United States)

    Joseph, Christine G; Wang, Xiang S; Scott, Joseph W; Bauzo, Rayna M; Xiang, Zhimin; Richards, Nigel G; Haskell-Luevano, Carrie

    2004-12-30

    The agouti-related protein (AGRP) is an endogenous antagonist of the centrally expressed melanocortin receptors. The melanocortin-4 receptor (MC4R) is involved in energy homeostasis, food intake, sexual function, and obesity. The endogenous hAGRP protein is 132 amino acids in length, possesses five disulfide bridges at the C-terminus of the molecule, and is expressed in the hypothalamus of the brain. We have previously reported that a monocyclic hAGRP(103-122) peptide is an antagonist at the melanocortin receptors expressed in the brain. Stereochemical inversion from the endogenous l- to d-isomers of single or multiple amino acid modifications in this monocyclic truncated hAGRP sequence resulted in molecules that are converted from melanocortin receptor antagonists into melanocortin receptor agonists. The Asp-Pro-Ala-Ala-Thr-Ala-Tyr-cyclo[Cys-Arg-DPhe-DPhe-Asn-Ala-Phe-Cys]-Tyr-Ala-Arg-Lys-Leu peptide resulted in a 60 nM melanocortin-1 receptor agonist that is 100-fold selective versus the mMC4R, 1000-fold selective versus the mMC3R, and ca. 180-fold selective versus the mMC5R. In attempts to identify putative ligand-receptor interactions that may be participating in the agonist induced stimulation of the MC4R, selected ligands were docked into a homology molecular model of the mMC4R. These modeling studies have putatively identified hAGRP ligand DArg111-mMC4RAsn115 (TM3) and the hAGRP DPhe113-mMC4RPhe176 (TM4) interactions as important for agonist activity.

  12. Drug and cell type-specific regulation of genes with different classes of estrogen receptor beta-selective agonists.

    Directory of Open Access Journals (Sweden)

    Sreenivasan Paruthiyil

    2009-07-01

    Full Text Available Estrogens produce biological effects by interacting with two estrogen receptors, ERalpha and ERbeta. Drugs that selectively target ERalpha or ERbeta might be safer for conditions that have been traditionally treated with non-selective estrogens. Several synthetic and natural ERbeta-selective compounds have been identified. One class of ERbeta-selective agonists is represented by ERB-041 (WAY-202041 which binds to ERbeta much greater than ERalpha. A second class of ERbeta-selective agonists derived from plants include MF101, nyasol and liquiritigenin that bind similarly to both ERs, but only activate transcription with ERbeta. Diarylpropionitrile represents a third class of ERbeta-selective compounds because its selectivity is due to a combination of greater binding to ERbeta and transcriptional activity. However, it is unclear if these three classes of ERbeta-selective compounds produce similar biological activities. The goals of these studies were to determine the relative ERbeta selectivity and pattern of gene expression of these three classes of ERbeta-selective compounds compared to estradiol (E(2, which is a non-selective ER agonist. U2OS cells stably transfected with ERalpha or ERbeta were treated with E(2 or the ERbeta-selective compounds for 6 h. Microarray data demonstrated that ERB-041, MF101 and liquiritigenin were the most ERbeta-selective agonists compared to estradiol, followed by nyasol and then diarylpropionitrile. FRET analysis showed that all compounds induced a similar conformation of ERbeta, which is consistent with the finding that most genes regulated by the ERbeta-selective compounds were similar to each other and E(2. However, there were some classes of genes differentially regulated by the ERbeta agonists and E(2. Two ERbeta-selective compounds, MF101 and liquiritigenin had cell type-specific effects as they regulated different genes in HeLa, Caco-2 and Ishikawa cell lines expressing ERbeta. Our gene profiling studies

  13. Comparison of the effects of the GABAB receptor positive modulator BHF177 and the GABAB receptor agonist baclofen on anxiety-like behavior, learning, and memory in mice.

    Science.gov (United States)

    Li, Xia; Risbrough, Victoria B; Cates-Gatto, Chelsea; Kaczanowska, Katarzyna; Finn, M G; Roberts, Amanda J; Markou, Athina

    2013-07-01

    γ-Aminobutyric acid B (GABAB) receptor activation is a potential therapeutic approach for the treatment of drug addiction, pain, anxiety, and depression. However, full agonists of this receptor induce side-effects, such as sedation, muscle relaxation, tolerance, and cognitive disruption. Positive allosteric modulators (PAMs) of the GABAB receptor may have similar therapeutic effects as agonists with superior side-effect profiles. The present study behaviorally characterized N-([1R,2R,4S]-bicyclo[2.2.1]hept-2-yl)-2-methyl-5-(4-[trifluoromethyl]phenyl)-4-pyrimidinamine (BHF177), a GABAB receptor PAM, in mouse models of anxiety-like behavior, learning and memory. In addition, the effects of BHF177 were compared with the agonist baclofen. Unlike the anxiolytic chlordiazepoxide, baclofen (0.5, 1.5, and 2.5 mg/kg, intraperitoneally) and BHF177 (10, 20, and 40 mg/kg, orally) had no effect on anxiety-like behavior in the elevated plus maze, light/dark box, or Vogel conflict test. Baclofen increased punished drinking in the Vogel conflict test, but this effect may be attributable to the analgesic actions of baclofen. At the highest dose tested (2.5 mg/kg), baclofen-treated mice exhibited sedation-like effects (i.e., reduced locomotor activity) across many of the tests, whereas BHF177-treated mice exhibited no sedation-like effects. BHF177 exhibited pro-convulsion properties only in mice, but not in rats, indicating that this effect may be species-specific. At doses that were not sedative or pro-convulsant, baclofen and BHF177 had no selective effects on fear memory retrieval in contextual and cued fear conditioning or spatial learning and memory in the Barnes maze. These data suggest that BHF177 has little sedative activity, no anxiolytic-like profile, and minimal impairment of learning and memory in mice. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Allosteric interactions between agonists and antagonists within the adenosine A2A receptor-dopamine D2 receptor heterotetramer.

    Science.gov (United States)

    Bonaventura, Jordi; Navarro, Gemma; Casadó-Anguera, Verònica; Azdad, Karima; Rea, William; Moreno, Estefanía; Brugarolas, Marc; Mallol, Josefa; Canela, Enric I; Lluís, Carme; Cortés, Antoni; Volkow, Nora D; Schiffmann, Serge N; Ferré, Sergi; Casadó, Vicent

    2015-07-07

    Adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromers are key modulators of striatal neuronal function. It has been suggested that the psychostimulant effects of caffeine depend on its ability to block an allosteric modulation within the A2AR-D2R heteromer, by which adenosine decreases the affinity and intrinsic efficacy of dopamine at the D2R. We describe novel unsuspected allosteric mechanisms within the heteromer by which not only A2AR agonists, but also A2AR antagonists, decrease the affinity and intrinsic efficacy of D2R agonists and the affinity of D2R antagonists. Strikingly, these allosteric modulations disappear on agonist and antagonist coadministration. This can be explained by a model that considers A2AR-D2R heteromers as heterotetramers, constituted by A2AR and D2R homodimers, as demonstrated by experiments with bioluminescence resonance energy transfer and bimolecular fluorescence and bioluminescence complementation. As predicted by the model, high concentrations of A2AR antagonists behaved as A2AR agonists and decreased D2R function in the brain.

  15. The pharmacology of TD-8954, a potent and selective 5-HT4 receptor agonist with gastrointestinal prokinetic properties

    Directory of Open Access Journals (Sweden)

    David T Beattie

    2011-05-01

    Full Text Available This study evaluated the in vitro and in vivo pharmacological properties of TD-8954, a potent and selective 5-HT4 receptor agonist. TD-8954 had high affinity (pKi = 9.4 for human recombinant 5-HT4(c (h5-HT4(c receptors, and selectivity (> 2,000-fold over all other 5-HT receptors and non-5-HT receptors, ion channels, enzymes and transporters tested (n = 78. TD-8954 produced an elevation of cAMP in HEK-293 cells expressing the h5-HT4(c receptor (pEC50 = 9.3, and contracted the guinea pig colonic longitudinal muscle/myenteric plexus (LMMP preparation (pEC50 = 8.6. TD-8954 had moderate intrinsic activity (IA in the in vitro assays. In conscious guinea pigs, subcutaneous (s.c. administration of TD 8954 (0.03 - 3 mg/kg increased the colonic transit of carmine red dye, reducing the time taken for its excretion. Following intraduodenal (i.d. dosing to anesthetized rats, TD 8954 (0.03 - 10 mg/kg evoked a dose-dependent relaxation of the esophagus. Following oral administration to conscious dogs, TD 8954 (10 and 30 µg/kg produced an increase in contractility of the antrum, duodenum and jejunum. In a single ascending oral dose study in healthy human subjects, TD-8954 (0.1 - 20 mg increased bowel movement frequency and reduced the time to first stool. It is concluded that TD-8954 is a potent and selective 5-HT4 receptor agonist in vitro, with robust in vivo stimulatory activity in the gastrointestinal (GI tract of guinea pigs, rats, dogs and humans. TD-8954 may have clinical utility in patients with disorders of reduced GI motility.

  16. Differential activation of catalase expression and activity by PPAR agonists: Implications for astrocyte protection in anti-glioma therapy☆

    Science.gov (United States)

    Khoo, Nicholas K.H.; Hebbar, Sachin; Zhao, Weiling; Moore, Steven A.; Domann, Frederick E.; Robbins, Mike E.

    2013-01-01

    Glioma survival is dismal, in part, due to an imbalance in antioxidant expression and activity. Peroxisome proliferator-activated receptor (PPAR) agonists have antineoplastic properties which present new redox-dependent targets for glioma anticancer therapies. Herein, we demonstrate that treatment of primary cultures of normal rat astrocytes with PPAR agonists increased the expression of catalase mRNA protein, and enzymatic activity. In contrast, these same agonists had no effect on catalase expression and activity in malignant rat glioma cells. The increase in steady-state catalase mRNA observed in normal rat astrocytes was due, in part, to de novo mRNA synthesis as opposed to increased catalase mRNA stability. Moreover, pioglitazone-mediated induction of catalase activity in normal rat astrocytes was completely blocked by transfection with a PPARγ-dominant negative plasmid. These data suggest that defects in PPAR-mediated signaling and gene expression may represent a block to normal catalase expression and induction in malignant glioma. The ability of PPAR agonists to differentially increase catalase expression and activity in normal astrocytes but not glioma cells suggests that these compounds might represent novel adjuvant therapeutic agents for the treatment of gliomas. PMID:24024139

  17. Treatment of type 2 diabetes with glucagon-like peptide-1 receptor agonists

    DEFF Research Database (Denmark)

    Hansen, K B; Knop, F K; Holst, Jens Juul

    2009-01-01

    of hypoglycaemia with GLP-1 receptor agonists is low, the compounds have clinically relevant effects on body weight, and data are suggesting beneficial effects on cardiovascular risk factors. Exenatide was released in 2005 for the treatment of type 2 diabetes and liraglutide is expected to be approved by the Food......The incretin system is an area of great interest for the development of new therapies for the management of type 2 diabetes. Existing antidiabetic drugs are often insufficient at getting patients to glycaemic goals. Furthermore, current treatment modalities are not able to prevent the continued...... ongoing decline in pancreatic beta-cell function and, lastly, they have a number of side effects including hypoglycaemia and weight gain. Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of pharmacological agents, which improve glucose homeostasis in a multifaceted way. Their effects...

  18. Therapeutic Effects of Melatonin Receptor Agonists on Sleep and Comorbid Disorders

    Directory of Open Access Journals (Sweden)

    Moshe Laudon

    2014-09-01

    Full Text Available Several melatonin receptors agonists (ramelteon, prolonged-release melatonin, agomelatine and tasimelteon have recently become available for the treatment of insomnia, depression and circadian rhythms sleep-wake disorders. The efficacy and safety profiles of these compounds in the treatment of the indicated disorders are reviewed. Accumulating evidence indicates that sleep-wake disorders and co-existing medical conditions are mutually exacerbating. This understanding has now been incorporated into the new Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5. Therefore, when evaluating the risk/benefit ratio of sleep drugs, it is pertinent to also evaluate their effects on wake and comorbid condition. Beneficial effects of melatonin receptor agonists on comorbid neurological, psychiatric, cardiovascular and metabolic symptomatology beyond sleep regulation are also described. The review underlines the beneficial value of enhancing physiological sleep in comorbid conditions.

  19. Alpha-2 receptor agonists for the treatment of posttraumatic stress disorder

    Directory of Open Access Journals (Sweden)

    Molly R Belkin

    2017-09-01

    Full Text Available Clonidine and guanfacine are alpha-2 receptor agonists that decrease sympathetic outflow from the central nervous system. Posttraumatic stress disorder (PTSD is an anxiety disorder that is theorized to be related to a hyperactive sympathetic nervous system. Currently, the only US Food and Drug Administration (FDA-approved medications for PTSD are the selective serotonin reuptake inhibitors (SSRIs sertraline and paroxetine. Sometimes use of the SSRIs may not lead to full remission and symptoms of hyperarousal often persist. This article specifically reviews the literature on alpha-2 receptor agonist use for the treatment of PTSD and concludes that while the evidence base is limited, these agents might be considered useful when SSRIs fail to treat symptoms of agitation and hyperarousal in patients with PTSD.

  20. The Novel, Nicotinic Alpha7 Receptor Partial Agonist, BMS-933043, Improves Cognition and Sensory Processing in Preclinical Models of Schizophrenia.

    Directory of Open Access Journals (Sweden)

    Linda J Bristow

    Full Text Available The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we characterized the novel agent, (2R-N-(6-(1H-imidazol-1-yl-4-pyrimidinyl-4'H-spiro[4-azabicyclo[2.2.2]octane-2,5'-[1,3]oxazol]-2'-amine (BMS-933043, in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat and 0.29 micromolar (human. BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM. BMS-933043 treatment i improved 24 hour novel object recognition memory in mice (0.1-10 mg/kg, sc, ii reversed MK-801-induced deficits in Y maze performance in mice (1-10 mg/kg, sc and set shift performance in rats (1-10 mg/kg, po and iii reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1-3 mg/kg, po. BMS-933043 also improved auditory gating (0.56-3 mg/kg, sc and mismatch negativity (0.03-3 mg/kg, sc in rats treated with S(+ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.

  1. Toll-like receptor-2 agonist-allergen coupling efficiently redirects Th2 cell responses and inhibits allergic airway eosinophilia.

    Science.gov (United States)

    Krishnaswamy, Jayendra Kumar; Jirmo, Adan Chari; Baru, Abdul Mannan; Ebensen, Thomas; Guzmán, Carlos A; Sparwasser, Tim; Behrens, Georg M N

    2012-12-01

    Toll-like receptor (TLR) agonists beneficially modulate allergic airway inflammation. However, the efficiency of TLR agonists varies considerably, and their exact cellular mechanisms (especially of TLR 2/6 agonists) are incompletely understood. We investigated at a cellular level whether the administration of the pharmacologically improved TLR2/6 agonist S-[2,3-bispalmitoyiloxy-(2R)-propyl]-R-cysteinyl-amido-monomethoxy polyethylene glycol (BPP) conjugated to antigenic peptide (BPP-OVA) could divert an existing Th2 response and influence airway eosinophilia. The effects of BPP-OVA on airway inflammation were assessed in a classic murine sensitization/challenge model and an adoptive transfer model, which involved the adoptive transfer of in vitro differentiated ovalbumin (OVA)-specific Th2 cells. Functional T-cell stimulation by lung dendritic cells (DCs) was determined both in vitro and in vivo, combined with a cytokine secretion analysis. A single mucosal application of BPP-OVA efficiently delivered antigen, led to TLR2-mediated DC activation, and resulted in OVA-specific T-cell proliferation via lung DCs in vivo. In alternative models of allergic airway disease, a single administration of BPP-OVA before OVA challenge (but not BPP alone) significantly reduced airway eosinophilia, most likely through altered antigen-specific T-cell stimulation via DCs. Analyses of adoptively transferred Th2-biased cells after BPP-OVA administration in vivo suggested that BPP-OVA guides antigen-specific Th2 cells to produce significantly higher amounts of IFN-γ upon allergen challenge. In conclusion, our data show for the first time that a single mucosal administration of a TLR 2/6 agonist-allergen conjugate can provoke IFN-γ responses in Th2-biased cells and alleviate allergic airway inflammation.

  2. Strategies to improve outcome after islet transplantation using the GLP-1 receptor agonist, extendin-4

    OpenAIRE

    Sharma, Amit

    2007-01-01

    Transplantation of pancreatic islets into the liver via the portal vein has emerged as a treatment option for patients with type I diabetes mellitus. However, loss of functional beta cell mass during isolation and following implantation is a major obstacle in obtaining good long-term results. Exendin-4, a glucagonlike peptide-1 (GLP-1) receptor agonist, improves glucose homeostasis in patients with diabetes. It also has anti-apoptotic and beta cell proliferative properties t...

  3. Maternal Characteristics of Women Exposed to Hypnotic Benzodiazepine Receptor Agonist during Pregnancy

    OpenAIRE

    Askaa, Bjarke; Jimenez-Solem, Espen; Enghusen Poulsen, Henrik; Traerup Andersen, Jon

    2014-01-01

    Background. There is little knowledge regarding the characteristics of women treated with hypnotic benzodiazepine receptor agonists (HBRAs) during pregnancy. In this large Danish cohort study, we characterize women exposed to HBRA during pregnancy. We determined changes in prevalence of HBRA use from 1997 to 2010 and exposure to HBRAs in relation to pregnancy. Methods. We performed a retrospective cohort study including 911,017 pregnant women in the period from 1997 to 2010. Information was r...

  4. NOpiates: Novel Dual Action Neuronal Nitric Oxide Synthase Inhibitors with μ-Opioid Agonist Activity.

    Science.gov (United States)

    Renton, Paul; Green, Brenda; Maddaford, Shawn; Rakhit, Suman; Andrews, John S

    2012-03-08

    A novel series of benzimidazole designed multiple ligands (DMLs) with activity at the neuronal nitric oxide synthase (nNOS) enzyme and the μ-opioid receptor was developed. Targeting of the structurally dissimilar heme-containing enzyme and the μ-opioid GPCR was predicated on the modulatory role of nitric oxide on μ-opioid receptor function. Structure-activity relationship studies yielded lead compound 24 with excellent nNOS inhibitory activity (IC50 = 0.44 μM), selectivity over both endothelial nitric oxide synthase (10-fold) and inducible nitric oxide synthase (125-fold), and potent μ-opioid binding affinity, K i = 5.4 nM. The functional activity as measured in the cyclic adenosine monosphospate secondary messenger assay resulted in full agonist activity (EC50 = 0.34 μM). This work represents a novel approach in the development of new analgesics for the treatment of pain.

  5. Functionalized Ergot-alkaloids as potential dopamine D3 receptor agonists for treatment of schizophrenia

    Science.gov (United States)

    Ivanova, Bojidarka; Spiteller, Michael

    2012-12-01

    The relationship between the molecular structure and physical properties of functionalized naturally occurred Ergot-alkaloids as potential dopamine D3 receptor agonists is presented. The molecular modeling of the ergoline-skeleton is based on the comprehensive theoretical study of the binding affinity of the isolated chemicals towards the active sites of the D3 sub-type receptor (D3R) loops. The studied proton accepting ability under physiological conditions allows classifying four types of monocationics, characterizing with the different binding modes to D3R involving selected amino acid residues to the active sites. These results marked the pharmaceutical potential and clinical usage of the reported compounds as antipsychotic drugs for Schizophrenia treatment, since they allowed evaluating the highlights of the different hypothesizes of the biochemical causes the illness. The applied complex approach for theoretical and experimental elucidation, including quantum chemistry method, electrospray ionization (ESI) and matrix assisted laser desorption/ionization (MALDI) mass spectrometric (MS) methods, nuclear magnetic resonance and vibrational IR and Raman spectroscopy on the isolated fifteen novel derivatives (1)-(15) and their different protonated forms (1a)-(15a) evidenced a strong dependence of molecular conformation, physical properties and binding affinity. Thus, the semi-synthetic functionalization of the naturally occurred products (NPs), provided significant possibilities to further molecular drugs-design and development of novel derivatives with wanted biological function, using the established profile of selected classes/families of NPs. The work described chiefly the non-linear (NL) approach for the interpretation of the mass chromatograms on the performed hybrid high performance liquid chromatography (HPLC) tandem MS/MS and MS/MS/MS experiments, discussing the merits and great diversity of instrumentation flexibility, thus achieving fundamental

  6. Beta-Adrenergic Receptors and Mechanisms in Asthma: The New Long-Acting Beta-Agonists

    Directory of Open Access Journals (Sweden)

    Robert G Townley

    1996-01-01

    Full Text Available The objective is to review β-adrenergic receptors and mechanisms in the immediate and late bronchial reaction in asthma and the new long-acting β-agonist. This will be discussed in light of the controversy of the potential adverse effect of regular use of long-acting β-agonists. We studied the effect of formoterol on the late asthmatic response (LAR and airway inflammation in guinea-pigs. Formoterol suppressed the LAR, antigen-induced airway inflammation and hyperresponsiveness, although isoproterenol failed to inhibit these parameters. β-Adrenergic hyporesponsiveness, and cholinergic and a- adrenergic hyperresponsiveness have been implicated in the pathogenesis of asthma. A decrease in β-adrenoreceptor function can result either from exogenously administered β-agonist or from exposure to allergens resulting in a late bronchial reaction. There is increasing evidence that eosinophils, macrophages, and lymphocytes which are of primary importance in the late bronchial reaction are also modulated by β2- adrenoreceptors. In functional studies of guinea-pig or human isolated trachea and lung parenchyma, PAF and certain cytokines significantly reduced the potency of isoproterenol to reverse methacholine- or histamine-induced contraction. The effect of glucocorticoids on pulmonary β-adrenergic receptors and responses suggests an important role for glucocorticoids to increase β-adrenergic receptors and responsiveness.

  7. Agonist and antagonist binding to rat brain muscarinic receptors: influence of aging

    International Nuclear Information System (INIS)

    Gurwitz, D.; Egozi, Y.; Henis, Y.I.; Kloog, Y.; Sokolovsky, M.

    1987-01-01

    The objective of the present study was to determine the binding properties of muscarinic receptors in six brain regions in mature and old rats of both sexes by employing direct binding of [ 3 H]-antagonist as well as of the labeled natural neurotransmitter, [ 3 H]-acetylcholine [( 3 H]-AcCh). In addition, age-related factors were evaluated in the modulation processes involved in agonist binding. The results indicate that as the rat ages the density of the muscarinic receptors is altered differently in the various brain regions: it is decreased in the cerebral cortex, hippocampus, striatum and olfactory bulb of both male and female rats, but is increased (58%) in the brain stem of senescent males while no significant change is observed for females. The use of the highly sensitive technique measuring direct binding of [ 3 H]-AcCh facilitated the separate detection of age-related changes in the two classes (high- and low-affinity) of muscarinic agonist binding sites. In old female rats the density of high-affinity [ 3 H]-AcCh binding sites was preserved in all tissues studied, indicating that the decreases in muscarinic receptor density observed with [ 3 H]-antagonist represent a loss of low-affinity agonist binding sites. In contrast, [ 3 H]-AcCh binding is decreased in the hypothalamus and increased in the brain stem of old male rats. These data imply sexual dimorphism of the aging process in central cholinergic mechanisms

  8. Nonergot dopamine-receptor agonists for treating Parkinson's disease – a network meta-analysis

    Directory of Open Access Journals (Sweden)

    Thorlund K

    2014-05-01

    Full Text Available Kristian Thorlund,1,2,4 Ping Wu,3,4 Eric Druyts,3,4 Shawn Eapen,3,4 Edward J Mills2–4 1Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada; 2Stanford Prevention Research Center, Stanford University, Stanford, CA, USA; 3Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada; 4Redwood Outcomes, Vancouver, BC, Canada Objective: To compare the efficacy of the three nonergot dopamine-receptor agonists (DAs pramipexole, ropinirole, and rotigotine for the treatment of early and advanced Parkinson's disease (PD. Materials and methods: Bayesian network meta-analyses were performed separately for early and advanced PD, and at time points 11–16 and 24–28 weeks. Outcomes for early PD included improvement on the Unified Parkinson's Disease Rating Scale (UPDRS activities in daily life (UPDRS-II, motor function (UPDRS-III, and their subtotal (UPDRS-II + III. Outcomes for advanced PD also included daily “off time” (hours, but not UPDRS-II + III. Results: Totals of 23 and 24 trials informed early and advanced PD analyses. For early PD UPDRS-II at 11–16 weeks, pramipexole and rotigotine were statistically significantly superior to placebo, but ropinirole was not. For UPDRS-III and UPDRS-II + III, all DAs were statistically significantly better than placebo and exhibited similar improvements. At 24–28 weeks, results were also statistically significant for all DAs versus placebo, and the magnitudes of improvements were similar for pramipexole, ropinirole and rotigotine. Advanced PD improvements on UPDRS-II, UPRDS-III, and off time were statistically significant for pramipexole, ropinirole, and rotigotine versus placebo. At 11–16 weeks, rotigotine yielded slightly smaller effects than ropinirole and pramipexole, but credible intervals on differences were wide. For off time, results were near identical. At 24–28 weeks, results were similar for all three outcomes. Ropinirole yielded a

  9. The putative imidazoline receptor agonist, harmane, promotes intracellular calcium mobilisation in pancreatic beta-cells.

    Science.gov (United States)

    Squires, Paul E; Hills, Claire E; Rogers, Gareth J; Garland, Patrick; Farley, Sophia R; Morgan, Noel G

    2004-10-06

    beta-Carbolines (including harmane and pinoline) stimulate insulin secretion by a mechanism that may involve interaction with imidazoline I(3)-receptors but which also appears to be mediated by actions that are additional to imidazoline receptor agonism. Using the MIN6 beta-cell line, we now show that both the imidazoline I(3)-receptor agonist, efaroxan, and the beta-carboline, harmane, directly elevate cytosolic Ca(2+) and increase insulin secretion but that these responses display different characteristics. In the case of efaroxan, the increase in cytosolic Ca(2+) was readily reversible, whereas, with harmane, the effect persisted beyond removal of the agonist and resulted in the development of a repetitive train of Ca(2+)-oscillations whose frequency, but not amplitude, was concentration-dependent. Initiation of the Ca(2+)-oscillations by harmane was independent of extracellular calcium but was sensitive to both dantrolene and high levels (20 mM) of caffeine, suggesting the involvement of ryanodine receptor-gated Ca(2+)-release. The expression of ryanodine receptor-1 and ryanodine receptor-2 mRNA in MIN6 cells was confirmed using reverse transcription-polymerase chain reaction (RT-PCR) and, since low concentrations of caffeine (1 mM) or thimerosal (10 microM) stimulated increases in [Ca(2+)](i), we conclude that ryanodine receptors are functional in these cells. Furthermore, the increase in insulin secretion induced by harmane was attenuated by dantrolene, consistent with the involvement of ryanodine receptors in mediating this response. By contrast, the smaller insulin secretory response to efaroxan was unaffected by dantrolene. Harmane-evoked changes in cytosolic Ca(2+) were maintained by nifedipine-sensitive Ca(2+)-influx, suggesting the involvement of L-type voltage-gated Ca(2+)-channels. Taken together, these data imply that harmane may interact with ryanodine receptors to generate sustained Ca(2+)-oscillations in pancreatic beta-cells and that this effect

  10. Identification of a potent and selective free fatty acid receptor 1 (FFA1/GPR40) agonist with favorable physicochemical and in vitro ADME properties

    DEFF Research Database (Denmark)

    Christiansen, Elisabeth; Urban, Christian; Grundmann, Manuel

    2011-01-01

    The free fatty acid receptor 1 (FFA1, also known as GPR40) enhances glucose-stimulated insulin secretion from pancreatic ß-cells and is recognized as an interesting new target for treatment of type 2 diabetes. Several series of selective FFA1 agonists are already known. Most of these are derived...... from free fatty acids (FFAs) or glitazones, and are relatively lipophilic. Aiming at the development of potent, selective and less lipophilic FFA1 agonists, the terminal phenyl of a known compound series was replaced by nitrogen containing heterocycles. This resulted in the identification of 37......, a selective FFA1 agonist with potent activity on recombinant human FFA1 receptors and on the rat insulinoma cell line INS-1E, optimal lipophilicity and excellent in vitro permeability and metabolic stability....

  11. Evaluation of Computational Docking to Identify Pregnane X Receptor Agonists in the ToxCast Database

    OpenAIRE

    Kortagere, Sandhya; Krasowski, Matthew D.; Reschly, Erica J.; Venkatesh, Madhukumar; Mani, Sridhar; Ekins, Sean

    2010-01-01

    Background The pregnane X receptor (PXR) is a key transcriptional regulator of many genes [e.g., cytochrome P450s (CYP2C9, CYP3A4, CYP2B6), MDR1] involved in xenobiotic metabolism and excretion. Objectives As part of an evaluation of different approaches to predict compound affinity for nuclear hormone receptors, we used the molecular docking program GOLD and a hybrid scoring scheme based on similarity weighted GoldScores to predict potential PXR agonists in the ToxCast database of pesticides...

  12. Triazolophostins: a library of novel and potent agonists of IP3 receptors

    OpenAIRE

    Vibhute, Amol M; Konieczny, Vera; Taylor, Colin William; Sureshan, Kana M

    2015-01-01

    IP3 receptors are channels that mediate the release of Ca2+ from the intracellular stores of cells stimulated by hormones or neurotransmitters. Adenophostin A (AdA) is the most potent agonist of IP3 receptors, with the β-anomeric adenine contributing to the increased potency. The potency of AdA and its stability towards the enzymes that degrade IP3 have aroused interest in AdA analogs for biological studies. The complex structure of AdA poses problems that have necessitated optimization of sy...

  13. Cell-Free Expression, Purification, and Characterization of the Functional β2-Adrenergic Receptor for Multianalyte Detection of β-Agonists.

    Science.gov (United States)

    Wang, Jian; Liu, Yuan; Zhang, Junhua; Han, Zhengzheng; Wang, Wei; Liu, Yang; Wei, Dong; Huang, Wei

    2017-11-01

    Large-scale expression of β 2 -adrenergic receptor (β 2 -AR) in functional form is necessary for establishment of receptor assays for detecting illegally abused β-adrenergic agonists (β-agonists). Cell-based heterologous expression systems have manycritical difficulties in synthesizing this membrane protein, such as low protein yields and aberrant folding. To overcome these challenges, the main objective of the present work was to synthesize large amounts of functional β 2 -AR in a cell-free system based on Escherichia coli extracts. A codon-optimized porcine β 2 -AR gene (codon adaptation index: 0.96) suitable for high expression in E. coli was synthesized and transcribed to the cell-free system, which contributed to increase the expression up to 1.1 mg/ml. After purification using Ni-affinity chromatography, the bioactivity of the purified receptor was measured by novel enzyme-linked receptor assays. It was determined that the relative affinities of the purified β 2 -AR for β-agonists in descending order were as follows: clenbuterol > salbutamol > ractopamine. Moreover, their IC 50 values were 45.99, 60.38, and 78.02 µg/liter, respectively. Although activity of the cell-free system was slightly lower than activity of systems based on insect and mammalian cells, this system should allow production of β 2 -AR in bulk amounts sufficient for the development of multianalyte screening methods for detecting β-agonist residues.

  14. Helminthosporic acid functions as an agonist for gibberellin receptor

    OpenAIRE

    Miyazaki, Sho; Jiang, Kai; Kobayashi, Masatomo; Asami, Tadao; Nakajima, Masatoshi

    2017-01-01

    Helminthosporol was isolated from a fungus, Helminthosporium sativum, as a natural plant growth regulator in 1963. It showed gibberellin-like bioactivity that stimulated the growth of the second leaf sheath of rice. After studying the structure–activity relationship between the compound and some synthesized analogs, it was found that helminthosporic acid (H-acid) has higher gibberellin-like activity and chemical stability than helminthosporol. In this study, we showed that (1) H-acid displays...

  15. Synthesis and SAR study of a novel series of dopamine receptor agonists

    DEFF Research Database (Denmark)

    Risgaard, R.; Jensen, M.; Jørgensen, M.

    2014-01-01

    The synthesis of a novel series of dopamine receptor agonists are described as well as their in vitro potency and efficacy on dopamine D and D receptors. This series was designed from pergolide and (4aR,10aR)-1-propyl-1,2,3,4,4a,5,10,10a-octahydro-benzo[g]quinolin-6-ol (PHBQ) and resulted in the ...... in the synthesis of (2R,4aR,10aR)-2-methylsulfanylmethyl-4-propyl-3,4,4a,5,10,10a-hexahydro-2H-naphtho[2,3-b][1,4]oxazin-9-ol (compound 27), which has a D and D receptor profile similar to that of the most recently approved drug for Parkinson's disease, rotigotine.......The synthesis of a novel series of dopamine receptor agonists are described as well as their in vitro potency and efficacy on dopamine D and D receptors. This series was designed from pergolide and (4aR,10aR)-1-propyl-1,2,3,4,4a,5,10,10a-octahydro-benzo[g]quinolin-6-ol (PHBQ) and resulted...

  16. Nalfurafine hydrochloride, a selective κ opioid receptor agonist, has no reinforcing effect on intravenous self-administration in rhesus monkeys

    Directory of Open Access Journals (Sweden)

    Kaoru Nakao

    2016-01-01

    Full Text Available Nalfurafine hydrochloride [(E-N-[17-(cyclopropylmethyl-4,5α-epoxy-3,14-dihydroxymorphinan-6β-yl]-3-(furan-3-yl-N-methylprop-2-enamide monohydrochloride; nalfurafine] is used in Japan as an antipruritic for the treatment of intractable pruritus in patients undergoing hemodialysis or with chronic liver disease. It is a potent and selective agonist at the κ opioid receptor, but also has weak and partial agonist activity at μ opioid receptors. Opioids, especially those acting at μ receptors, carry a risk of abuse. This is an important factor in the consideration of therapeutic risk vs. benefit in clinical use and the potential for misuse as a public health problem. It is therefore necessary to carefully evaluate the reinforcing effects of nalfurafine. To this end, we investigated intravenous self-administration of nalfurafine in rhesus monkeys. The number of self-administration of nalfurafine at doses of 0.0625, 0.125 and 0.25 μg/kg/infusion was not higher than that of saline in rhesus monkeys that frequently self-administered pentazocine (0.25 mg/kg/infusion. These results indicate that nalfurafine has no reinforcing effect in rhesus monkeys in the intravenous self-administration paradigm.

  17. Effects of mosapride citrate, a 5-HT4-receptor agonist, on gastric distension-induced visceromotor response in conscious rats.

    Science.gov (United States)

    Seto, Yasuhiro; Yoshida, Naoyuki; Kaneko, Hiroshi

    2011-01-01

    Mosapride citrate (mosapride), a prokinetic agent with 5-HT(4)-receptor agonistic activity, is known to enhance gastric emptying and alleviate symptoms in patients with functional dyspepsia (FD). As hyperalgesia and delayed gastric emptying play an important role in the pathogenesis of FD, we used in this study balloon gastric distension to enable abdominal muscle contractions and characterized the visceromotor response (VMR) to such distension in conscious rats. We also investigated the effects of mosapride on gastric distension-induced VMR in the same model. Mosapride (3-10 mg/kg, p.o.) dose-dependently inhibited gastric distension-induced VMR in rats. However, itopride even at 100 mg/kg failed to inhibit gastric distension-induced VMR in rats. Additionally, a major metabolite M1 of mosapride, which possesses 5-HT(3)-receptor antagonistic activity, inhibited gastric distension-induced VMR. The inhibitory effect of mosapride on gastric distension-induced visceral pain was partially, but significantly inhibited by SB-207266, a selective 5-HT(4)-receptor antagonist. This study shows that mosapride inhibits gastric distension-induced VMR in conscious rats. The inhibitory effect of mosapride is mediated via activation of 5-HT(4) receptors and blockage of 5-HT(3) receptors by a mosapride metabolite. This finding indicates that mosapride may be useful in alleviating FD-associated gastrointestinal symptoms via increase in pain threshold.

  18. CL316,243, a β3-adrenergic receptor agonist, induces muscle hypertrophy and increased strength.

    Science.gov (United States)

    Puzzo, Daniela; Raiteri, Roberto; Castaldo, Clotilde; Capasso, Raffaele; Pagano, Ester; Tedesco, Mariateresa; Gulisano, Walter; Drozd, Lisaveta; Lippiello, Pellegrino; Palmeri, Agostino; Scotto, Pietro; Miniaci, Maria Concetta

    2016-11-22

    Studies in vitro have demonstrated that β3-adrenergic receptors (β3-ARs) regulate protein metabolism in skeletal muscle by promoting protein synthesis and inhibiting protein degradation. In this study, we evaluated whether activation of β3-ARs by the selective agonist CL316,243 modifies the functional and structural properties of skeletal muscles of healthy mice. Daily injections of CL316,243 for 15 days resulted in a significant improvement in muscle force production, assessed by grip strength and weight tests, and an increased myofiber cross-sectional area, indicative of muscle hypertrophy. In addition, atomic force microscopy revealed a significant effect of CL316,243 on the transversal stiffness of isolated muscle fibers. Interestingly, the expression level of mammalian target of rapamycin (mTOR) downstream targets and neuronal nitric oxide synthase (NOS) was also found to be enhanced in tibialis anterior and soleus muscles of CL316,243 treated mice, in accordance with previous data linking β3-ARs to mTOR and NOS signaling pathways. In conclusion, our data suggest that CL316,243 systemic administration might be a novel therapeutic strategy worthy of further investigations in conditions of muscle wasting and weakness associated with aging and muscular diseases.

  19. Agonist-induced alterations in lymphocyte β-adrenergic receptor photoaffintiy labelling: effects of phenylarsine oxide

    International Nuclear Information System (INIS)

    Feldman, R.D.; McArdle, W.; Lai, C.

    1986-01-01

    In several models, desensitization of the β-adrenergic receptor (βAR) is associated with a decrease in binding of hydrophilic but not hydrophobic βAR ligands. This suggests a sequestration of cell surface βAR. Desensitization of the lymphobyte βAR is also associated with a selective reduction in the photoaffinity labelling of a 55K βAR protein as compared to a 68K βAR protein. In order to examine the relationship between sequestration and reduction in labelling of the 55K peptide, the authors have studied the effect of phenylarsine oxide (PAO; an inhibitor of sequestration) on lymphocyte βAR desensitization. Incubation of cells with PAO prior to desensitization did not block the consequent reduction in isoproterenol-stimulated adenylate cyclase activity. However, the agonist-induced reduction in binding of the hydrophilic βAR ligand CGP-12177 was blocked by PAO (without PAO:57 +/- 4% of control, with PAO: 97 +/- 2% of control). Photolabelling studies with [ 125 I] iodocyanopindolol diazirine revealed that PAO pretreatment also blocked the selective loss in labelling of the 55K βAR protein seen with desensitization. These data suggest that loss of labelling of the 55K protein of the βAR is closely coupled to βAR sequestration

  20. Mutational analysis of the extracellular disulphide bridges of the atypical chemokine receptor ACKR3/CXCR7 uncovers multiple binding and activation modes for its chemokine and endogenous non-chemokine agonists.

    Science.gov (United States)

    Szpakowska, Martyna; Meyrath, Max; Reynders, Nathan; Counson, Manuel; Hanson, Julien; Steyaert, Jan; Chevigné, Andy

    2018-07-01

    The atypical chemokine receptor ACKR3/CXCR7 plays crucial roles in numerous physiological processes but also in viral infection and cancer. ACKR3 shows strong propensity for activation and, unlike classical chemokine receptors, can respond to chemokines from both the CXC and CC families as well as to the endogenous peptides BAM22 and adrenomedullin. Moreover, despite belonging to the G protein coupled receptor family, its function appears to be mainly dependent on β-arrestin. ACKR3 has also been shown to continuously cycle between the plasma membrane and the endosomal compartments, suggesting a possible role as a scavenging receptor. So far, the molecular basis accounting for these atypical binding and signalling properties remains elusive. Noteworthy, ACKR3 extracellular domains bear three disulphide bridges. Two of them lie on top of the two main binding subpockets and are conserved among chemokine receptors, and one, specific to ACKR3, forms an intra-N terminus four-residue-loop of so far unknown function. Here, by mutational and functional studies, we examined the impact of the different disulphide bridges for ACKR3 folding, ligand binding and activation. We showed that, in contrast to most classical chemokine receptors, none of the extracellular disulphide bridges was essential for ACKR3 function. However, the disruption of the unique ACKR3 N-terminal loop drastically reduced the binding of CC chemokines whereas it only had a mild impact on CXC chemokine binding. Mutagenesis also uncovered that chemokine and endogenous non-chemokine ligands interact and activate ACKR3 according to distinct binding modes characterized by different transmembrane domain subpocket occupancy and N-terminal loop contribution, with BAM22 mimicking the binding mode of CC chemokine N terminus. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Neural correlate of resting-state functional connectivity under α2 adrenergic receptor agonist, medetomidine.

    Science.gov (United States)

    Nasrallah, Fatima A; Lew, Si Kang; Low, Amanda Si-Min; Chuang, Kai-Hsiang

    2014-01-01

    Correlative fluctuations in functional MRI (fMRI) signals across the brain at rest have been taken as a measure of functional connectivity, but the neural basis of this resting-state MRI (rsMRI) signal is not clear. Previously, we found that the α2 adrenergic agonist, medetomidine, suppressed the rsMRI correlation dose-dependently but not the stimulus evoked activation. To understand the underlying electrophysiology and neurovascular coupling, which might be altered due to the vasoconstrictive nature of medetomidine, somatosensory evoked potential (SEP) and resting electroencephalography (EEG) were measured and correlated with corresponding BOLD signals in rat brains under three dosages of medetomidine. The SEP elicited by electrical stimulation to both forepaws was unchanged regardless of medetomidine dosage, which was consistent with the BOLD activation. Identical relationship between the SEP and BOLD signal under different medetomidine dosages indicates that the neurovascular coupling was not affected. Under resting state, EEG power was the same but a depression of inter-hemispheric EEG coherence in the gamma band was observed at higher medetomidine dosage. Different from medetomidine, both resting EEG power and BOLD power and coherence were significantly suppressed with increased isoflurane level. Such reduction was likely due to suppressed neural activity as shown by diminished SEP and BOLD activation under isoflurane, suggesting different mechanisms of losing synchrony at resting-state. Even though, similarity between electrophysiology and BOLD under stimulation and resting-state implicates a tight neurovascular coupling in both medetomidine and isoflurane. Our results confirm that medetomidine does not suppress neural activity but dissociates connectivity in the somatosensory cortex. The differential effect of medetomidine and its receptor specific action supports the neuronal origin of functional connectivity and implicates the mechanism of its sedative

  2. Tumor necrosis factor α sensitizes spinal cord TRPV1 receptors to the endogenous agonist N-oleoyldopamine

    Directory of Open Access Journals (Sweden)

    Spicarova Diana

    2010-08-01

    Full Text Available Abstract Modulation of synaptic transmission in the spinal cord dorsal horn is thought to be involved in the development and maintenance of different pathological pain states. The proinflamatory cytokine, tumor necrosis factor α (TNFα, is an established pain modulator in both the peripheral and the central nervous system. Up-regulation of TNFα and its receptors (TNFR in dorsal root ganglion (DRG cells and in the spinal cord has been shown to play an important role in neuropathic and inflammatory pain conditions. Transient receptor potential vanilloid 1 (TRPV1 receptors are known as molecular integrators of nociceptive stimuli in the periphery, but their role on the spinal endings of nociceptive DRG neurons is unclear. The endogenous TRPV1 receptor agonist N-oleoyldopamine (OLDA was shown previously to activate spinal TRPV1 receptors. In our experiments the possible influence of TNFα on presynaptic spinal cord TRPV1 receptor function was investigated. Using the patch-clamp technique, miniature excitatory postsynaptic currents (mEPSCs were recorded in superficial dorsal horn neurons in acute slices after incubation with 60 nM TNFα. A population of dorsal horn neurons with capsaicin sensitive primary afferent input recorded after the TNFα pretreatment had a basal mEPSC frequency of 1.35 ± 0.20 Hz (n = 13, which was significantly higher when compared to a similar population of neurons in control slices (0.76 ± 0.08 Hz; n = 53; P

  3. Can the anti-inflammatory activities of β2-agonists be harnessed in the clinical setting?

    Directory of Open Access Journals (Sweden)

    Theron AJ

    2013-11-01

    Full Text Available Annette J Theron,1,2 Helen C Steel,1 Gregory R Tintinger,1 Charles Feldman,3 Ronald Anderson1 1Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, Faculty of Health Sciences, University of Pretoria, 2Tshwane Academic Division of the National Health Laboratory Service, Pretoria, 3Division of Pulmonology, Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand and Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa Abstract: Beta2-adrenoreceptor agonists (β2-agonists are primarily bronchodilators, targeting airway smooth muscle and providing critical symptomatic relief in conditions such as bronchial asthma and chronic obstructive pulmonary disease. These agents also possess broad-spectrum, secondary, anti-inflammatory properties. These are mediated largely, though not exclusively, via interactions with adenylyl cyclase-coupled β2-adrenoreceptors on a range of immune and inflammatory cells involved in the immunopathogenesis of acute and chronic inflammatory disorders of the airways. The clinical relevance of the anti-inflammatory actions of β2-agonists, although often effective in the experimental setting, remains contentious. The primary objectives of the current review are: firstly, to assess the mechanisms, both molecular and cell-associated, that may limit the anti-inflammatory efficacy of β2-agonists; secondly, to evaluate pharmacological strategies, several of which are recent and innovative, that may overcome these limitations. These are preceded by a consideration of the various types of β2-agonists, their clinical applications, and spectrum of anti-inflammatory activities, particularly those involving adenosine 3',5'-cyclic adenosine monophosphate-activated protein kinase-mediated clearance of cytosolic calcium, and altered gene expression in immune and inflammatory cells. Keywords: adenylyl cyclase, corticosteroids, cyclic AMP, muscarinic

  4. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    The family C seven transmembrane (7TM) receptors constitutes a small and especially well characterized subfamily of the large 7TM receptor superfamily. Approximately 50% of current prescription drugs target 7TM receptors, this biologically important family represents the largest class of drug...... to be fully defined. This review presents the biochemical support for family C 7TM receptor dimerization and discusses its importance for receptor biosynthesis, surface expression, ligand binding and activation, since lessons learnt here may well be applicable to the whole superfamily of 7TM receptors.......-targets today. It is well established that family C 7TM receptors form homo- or hetero-dimers on the cell surface of living cells. The large extra-cellular domains (ECD) have been crystallized as a dimer in the presence and absence of agonist. Upon agonist binding, the dimeric ECD undergoes large conformational...

  5. Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

    Science.gov (United States)

    Thompson, Aiysha; Stephens, Jeffrey W; Bain, Stephen C; Kanamarlapudi, Venkateswarlu

    2016-01-01

    The glucagon-like peptide receptor (GLP-1R), which is a G-protein coupled receptor (GPCR), signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R) expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39) and JANT-4 and the orthosteric binding site mutation (V36A) in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

  6. Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

    Directory of Open Access Journals (Sweden)

    Aiysha Thompson

    Full Text Available The glucagon-like peptide receptor (GLP-1R, which is a G-protein coupled receptor (GPCR, signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39 and JANT-4 and the orthosteric binding site mutation (V36A in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

  7. Adrenergic Agonists Bind to Adrenergic-Receptor-Like Regions of the Mu Opioid Receptor, Enhancing Morphine and Methionine-Enkephalin Binding: A New Approach to "Biased Opioids"?

    Science.gov (United States)

    Root-Bernstein, Robert; Turke, Miah; Subhramanyam, Udaya K Tiruttani; Churchill, Beth; Labahn, Joerg

    2018-01-17

    Extensive evidence demonstrates functional interactions between the adrenergic and opioid systems in a diversity of tissues and organs. While some effects are due to receptor and second messenger cross-talk, recent research has revealed an extracellular, allosteric opioid binding site on adrenergic receptors that enhances adrenergic activity and its duration. The present research addresses whether opioid receptors may have an equivalent extracellular, allosteric adrenergic binding site that has similar enhancing effects on opioid binding. Comparison of adrenergic and opioid receptor sequences revealed that these receptors share very significant regions of similarity, particularly in some of the extracellular and transmembrane regions associated with adrenergic binding in the adrenergic receptors. Five of these shared regions from the mu opioid receptor (muOPR) were synthesized as peptides and tested for binding to adrenergic, opioid and control compounds using ultraviolet spectroscopy. Adrenergic compounds bound to several of these muOPR peptides with low micromolar affinity while acetylcholine, histamine and various adrenergic antagonists did not. Similar studies were then conducted with purified, intact muOPR with similar results. Combinations of epinephrine with methionine enkephalin or morphine increased the binding of both by about half a log unit. These results suggest that muOPR may be allosterically enhanced by adrenergic agonists.

  8. Synthesis and enantiopharmacology of new AMPA-kainate receptor agonists

    DEFF Research Database (Denmark)

    Conti, P; De Amici, M; De Sarro, G

    1999-01-01

    . The convulsant properties of all the compounds were evaluated in vivo on DBA/2 mice after icv injection. CIP-A showed a convulsant activity, measured as tonus and clonus seizures, 18-65 times higher than that produced by AMPA. It was also quite active after ip administration, since it induced seizures in mice...... at doses as low as 3.2 nmol/mouse. On the basis of the above-reported results we prepared and tested the enantiomers of CIP-A and CIP-B, obtained by reacting (S)-3,4-didehydroproline and (R)-3,4-didehydroproline, respectively, with ethoxycarbonylformonitrile oxide. In all the tests the S-form, CIP...

  9. Design and development of a peptide-based adiponectin receptor agonist for cancer treatment

    Directory of Open Access Journals (Sweden)

    Lovas Sandor

    2011-10-01

    displayed excellent stability (at least 30 min in mouse blood or serum and did not induce gross toxic effects at 5-50 mg/kg bolus doses in normal CBA/J mice. Conclusions ADP 355 is a first-in-class adiponectin receptor agonist. Its biological activity, superior stability in biological fluids as well as acceptable toxicity profile indicate that the peptidomimetic represents a true lead compound for pharmaceutical development to replace low adiponectin levels in cancer and other malignancies.

  10. The peroxisome proliferator-activated receptor alpha agonist fenofibrate has no effect on insulin sensitivity compared to atorvastatin in type 2 diabetes mellitus; a randomised, double-blind controlled trial.

    Science.gov (United States)

    Black, R Neil A; Ennis, Cieran N; Young, Ian S; Hunter, Steven J; Atkinson, A Brew; Bell, Patrick M

    2014-01-01

    Assess insulin sensitivity after treatment with a selective PPAR-alpha agonist compared to an HMG CoA reductase inhibitor in human subjects with type 2 diabetes mellitus. Thirteen subjects with Type 2 diabetes mellitus were studied in a double-blind crossover design with 4-week placebo run-in and washout and 12-week treatment periods, randomised to micronised fenofibrate 267 mg or atorvastatin 10mg daily followed by the alternate drug in the second period. Insulin resistance was measured using the isoglycaemic hyperinsulinaemic clamp method with isotope dilution. Weight, physical activity and other medications did not change. Total cholesterol (mean +/- standard error) was 4.60+/-0.21 versus 3.9+/-0.22 mmol/L after fenofibrate and atorvastatin respectively, p19 versus 1.95+/-0.23 mmol/L, p1.64+/-0.23 versus 1.84+/-0.26 mmol/L, pInsulin-stimulated whole-body glucose disposal (35.4+/-3.1 versus 33.2+/-3.0 μmol/kg/min) and nadir endogenous glucose production (6.2+/-1.4 versus 7.0+/-1.1 μmol/kg/min) revealed no significant differences in effects of the treatments. In human subjects with Type 2 diabetes mellitus there were characteristic differences in lipid profile changes but no difference in insulin sensitivity after treatment with micronised fenofibrate compared to atorvastatin. This study finds no evidence of increased insulin sensitivity using this selective PPAR-alpha agonist over a commonly used statin at these doses. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Novel Zn2+ Modulated GPR39 Receptor Agonists Do Not Drive Acute Insulin Secretion in Rodents.

    Directory of Open Access Journals (Sweden)

    Ola Fjellström

    Full Text Available Type 2 diabetes (T2D occurs when there is insufficient insulin release to control blood glucose, due to insulin resistance and impaired β-cell function. The GPR39 receptor is expressed in metabolic tissues including pancreatic β-cells and has been proposed as a T2D target. Specifically, GPR39 agonists might improve β-cell function leading to more adequate and sustained insulin release and glucose control. The present study aimed to test the hypothesis that GPR39 agonism would improve glucose stimulated insulin secretion in vivo. A high throughput screen, followed by a medicinal chemistry program, identified three novel potent Zn2+ modulated GPR39 agonists. These agonists were evaluated in acute rodent glucose tolerance tests. The results showed a lack of glucose lowering and insulinotropic effects not only in lean mice, but also in diet-induced obese (DIO mice and Zucker fatty rats. It is concluded that Zn2+ modulated GPR39 agonists do not acutely stimulate insulin release in rodents.

  12. Antithetic regulation by β-adrenergic receptors of Gq receptor signaling via phospholipase C underlies the airway β-agonist paradox

    OpenAIRE

    McGraw, Dennis W.; Almoosa, Khalid F.; Paul, Richard J.; Kobilka, Brian K.; Liggett, Stephen B.

    2003-01-01

    β-adrenergic receptors (βARs) relax airway smooth muscle and bronchodilate, but chronic β-agonist treatment in asthma causes increased sensitivity to airway constriction (hyperreactivity) and is associated with exacerbations. This paradox was explored using mice with ablated βAR genes (βAR–/–) and transgenic mice overexpressing airway smooth muscle β2AR (β2AR-OE) representing two extremes: absence and persistent activity of airway βAR. Unexpectedly, βAR–/– mice, lacking these bronchodilating ...

  13. Structure-activity relationships of rosiglitazone for peroxisome proliferator-activated receptor gamma transrepression.

    Science.gov (United States)

    Toyota, Yosuke; Nomura, Sayaka; Makishima, Makoto; Hashimoto, Yuichi; Ishikawa, Minoru

    2017-06-15

    Anti-inflammatory effects of peroxisome proliferator-activated receptor gamma (PPRAγ) ligands are thought to be largely due to PPARγ-mediated transrepression. Thus, transrepression-selective PPARγ ligands without agonistic activity or with only partial agonistic activity should exhibit anti-inflammatory properties with reduced side effects. Here, we investigated the structure-activity relationships (SARs) of PPARγ agonist rosiglitazone, focusing on transrepression activity. Alkenic analogs showed slightly more potent transrepression with reduced efficacy of transactivating agonistic activity. Removal of the alkyl group on the nitrogen atom improved selectivity for transrepression over transactivation. Among the synthesized compounds, 3l exhibited stronger transrepressional activity (IC 50 : 14μM) and weaker agonistic efficacy (11%) than rosiglitazone or pioglitazone. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Virtual screening studies of Chinese medicine Coptidis Rhizoma as alpha7 nicotinic acetylcholine receptor agonists for treatment of Alzheimer's disease

    Science.gov (United States)

    Xiang, Li; Xu, Youdong; Zhang, Yan; Meng, Xianli; Wang, Ping

    2015-04-01

    Alzheimer's disease (AD) is an age-related neurodegenerative disease. Extensive in vitro and in vivo experiments have proved that the decreased activity of the cholinergic neuron is responsible for the memory and cognition deterioration. The alpha7 nicotinic acetylcholine receptor (α7-nAChR) is proposed to a drug target of AD, and compounds which acting as α7-nAChR agonists are considered as candidates in AD treatment. Chinese medicine CoptidisRhizoma and its compounds are reported in various anti-AD effects. In this study, virtual screening, docking approaches and hydrogen bond analyses were applied to screen potential α7-nAChR agonists from CoptidisRhizome. The 3D structure of the protein was obtained from PDB database. 87 reported compounds were included in this research and their structures were accessed by NCBI Pubchem. Docking analysis of the compounds was performed using AutoDock 4.2 and AutoDock Vina. The images of the binding modes hydrogen bonds and the hydrophobic interaction were rendered with PyMOL1.5.0.4. and LigPlot+ respectively. Finally, N-tran-feruloyltyramine, isolariciresinol, flavanone, secoisolariciresinol, (+)-lariciresinol and dihydrochalcone, exhibited the lowest docking energy of protein-ligand complex. The results indicate these 6 compounds are potential α7 nAChR agonists, and expected to be effective in AD treatment.

  15. Estrogen receptor beta-selective agonists stimulate calcium oscillations in human and mouse embryonic stem cell-derived neurons.

    Directory of Open Access Journals (Sweden)

    Lili Zhang

    2010-07-01

    Full Text Available Estrogens are used extensively to treat hot flashes in menopausal women. Some of the beneficial effects of estrogens in hormone therapy on the brain might be due to nongenomic effects in neurons such as the rapid stimulation of calcium oscillations. Most studies have examined the nongenomic effects of estrogen receptors (ER in primary neurons or brain slices from the rodent brain. However, these cells can not be maintained continuously in culture because neurons are post-mitotic. Neurons derived from embryonic stem cells could be a potential continuous, cell-based model to study nongenomic actions of estrogens in neurons if they are responsive to estrogens after differentiation. In this study ER-subtype specific estrogens were used to examine the role of ERalpha and ERbeta on calcium oscillations in neurons derived from human (hES and mouse embryonic stem cells. Unlike the undifferentiated hES cells the differentiated cells expressed neuronal markers, ERbeta, but not ERalpha. The non-selective ER agonist 17beta-estradiol (E(2 rapidly increased [Ca2+]i oscillations and synchronizations within a few minutes. No change in calcium oscillations was observed with the selective ERalpha agonist 4,4',4''-(4-Propyl-[1H]-pyrazole-1,3,5-triyltrisphenol (PPT. In contrast, the selective ERbeta agonists, 2,3-bis(4-Hydroxyphenyl-propionitrile (DPN, MF101, and 2-(3-fluoro-4-hydroxyphenyl-7-vinyl-1,3 benzoxazol-5-ol (ERB-041; WAY-202041 stimulated calcium oscillations similar to E(2. The ERbeta agonists also increased calcium oscillations and phosphorylated PKC, AKT and ERK1/2 in neurons derived from mouse ES cells, which was inhibited by nifedipine demonstrating that ERbeta activates L-type voltage gated calcium channels to regulate neuronal activity. Our results demonstrate that ERbeta signaling regulates nongenomic pathways in neurons derived from ES cells, and suggest that these cells might be useful to study the nongenomic mechanisms of estrogenic compounds.

  16. 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

    2013-01-01

    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......-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...... of the agonists in the orthosteric site. The carbonyl group of DZP is predicted to interact with two threonines a1T206 and c2T142, similar to the acidic moiety of GABA. The chlorine atom of DZP is placed near the important a1H101 and the N-methyl group near a1Y159, a1T206, and a1Y209. We present a binding mode...

  17. Profound and Rapid Reduction in Body Temperature Induced by the Melanocortin Receptor Agonists

    Science.gov (United States)

    Xu, Yuanzhong; Kim, Eun Ran; Fan, Shengjie; Xia, Yan; Xu, Yong; Huang, Cheng; Tong, Qingchun

    2014-01-01

    The melanocortin receptor 4 (MC4R) plays a major role in body weight regulation and its agonist MTII has been widely used to study the role of MC4Rs in energy expenditure promotion and feeding reduction. Unexpectedly, we observed that intraperitoneal (i.p.) administration of MTII induced a rapid reduction in both body temperature and energy expenditure, which was independent of its effect on feeding and followed by a prolonged increase in energy expenditure. The rapid reduction was at least partly mediated by brain neurons since intracerebroventricular (icv) administration of alpha melanocyte-stimulating hormone, an endogenous melanocortin receptor agonist, produced a similar response. In addition, the body temperature-lowering effect of MTII was independent of the presence of MC4Rs, but in a similar fashion to the previously shown effect on body temperature by 5′AMP. Moreover, β-adrenergic receptors (β-ARs) were required for the recovery from low body temperature induced by MTII and further pharmacological studies showed that the MTII’s effect on body temperature may be partially mediated by the vasopressin V1a receptors. Collectively, our results reveal a previously unappreciated role for the melanocortin pathway in rapidly lowering body temperature. PMID:25065745

  18. Profound and rapid reduction in body temperature induced by the melanocortin receptor agonists.

    Science.gov (United States)

    Xu, Yuanzhong; Kim, Eun Ran; Fan, Shengjie; Xia, Yan; Xu, Yong; Huang, Cheng; Tong, Qingchun

    2014-08-22

    The melanocortin receptor 4 (MC4R) plays a major role in body weight regulation and its agonist MTII has been widely used to study the role of MC4Rs in energy expenditure promotion and feeding reduction. Unexpectedly, we observed that intraperitoneal (i.p.) administration of MTII induced a rapid reduction in both body temperature and energy expenditure, which was independent of its effect on feeding and followed by a prolonged increase in energy expenditure. The rapid reduction was at least partly mediated by brain neurons since intracerebroventricular (icv) administration of alpha melanocyte-stimulating hormone, an endogenous melanocortin receptor agonist, produced a similar response. In addition, the body temperature-lowering effect of MTII was independent of the presence of MC4Rs, but in a similar fashion to the previously shown effect on body temperature by 5'AMP. Moreover, β-adrenergic receptors (β-ARs) were required for the recovery from low body temperature induced by MTII and further pharmacological studies showed that the MTII's effect on body temperature may be partially mediated by the vasopressin V1a receptors. Collectively, our results reveal a previously unappreciated role for the melanocortin pathway in rapidly lowering body temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. (-)-N-[11C]propyl-norapomorphine: a positron-labeled dopamine agonist for PET imaging of D2 receptors

    International Nuclear Information System (INIS)

    Hwang, Dah-Ren; Kegeles, Lawrence S.; Laruelle, Marc

    2000-01-01

    Imaging neuroreceptors with radiolabeled agonists might provide valuable information on the in vivo agonist affinity states of receptors of interest. We report here the radiosynthesis, biodistribution in rodents, and imaging studies in baboons of [ 11 C]-labeled (-)-N-propyl-norapomorphine [(-)-NPA]. (-)-[ 11 C]NPA was prepared by reacting norapomorphine with [ 11 C]propionyl chloride and a lithium aluminum hydride reduction. [ 11 C]Propionyl chloride was prepared by reacting [ 11 C]CO 2 with ethylmagnesium bromide, followed by reacting with phthaloyl chloride. The radiochemical yield of (-)-[ 11 C]NPA was 2.5% at end of synthesis (EOS), and the synthesis time was 60 min. The specific activity was 1700±1900 mCi/μmol ( N=7; ranged 110-5200 mCi/μmol at EOS). Rodent biodistribution studies showed high uptake of [ 11 C](-)-NPA in D 2 receptor-rich areas, and the striatum/cerebellum ratios were 1.7, 3.4, and 4.4 at 5 min, 30 min, and 60 min postinjection, respectively. Pretreating the animals with haloperidol (1 mg/kg) decreased the striatum/cerebellum ratio at 30 min postinjection to 1.3. (-)-[ 11 C]NPA was also evaluated via baboon positron emission tomography (PET) studies. Under control conditions ( N=4), rapid uptake of the tracer was observed and the striatum/cerebellum ratio reached 2.86±0.15 at 45 min postinjection. Following haloperidol pretreatment (0.2 mg/kg IV), the striatum/cerebellum ratio was 1.29 at 45 min postinjection. The result demonstrated the existence of specific binding of this new tracer to the D 2 receptor. To our knowledge, the current finding of a striatum/cerebellum ratio of 2.8 in baboon was the highest reported with a radiolabeled D 2 agonist. (-)-[ 11 C]NPA is a promising new D 2 agonist PET tracer for probing D 2 receptors in vivo using PET

  20. Effect of GABA receptor agonists or antagonists injected spinally on the blood glucose level in mice.

    Science.gov (United States)

    Sim, Yun-Beom; Park, Soo-Hyun; Kang, Yu-Jung; Kim, Sung-Su; Kim, Chea-Ha; Kim, Su-Jin; Jung, Jun-Sub; Ryu, Ohk-Hyun; Choi, Moon-Gi; Suh, Hong-Won

    2013-05-01

    The possible roles of gamma-amino butyric acid (GABA) receptors located in the spinal cord for the regulation of the blood glucose level were studied in ICR mice. We found in the present study that intrathecal (i.t.) injection with baclofen (a GABAB receptor agonist; 1-10 μg/5 μl) or bicuculline (a GABAA receptor antagonist; 1-10 μg/5 μl) caused an elevation of the blood glucose level in a dose-dependent manner. The hyperglycemic effect induced by baclofen was more pronounced than that induced by bicuculline. However, muscimol (a GABAA receptor agonist; 1-5 μg/5 μl) or phaclofen (a GABAB receptor antagonist; 5-10 μg/5 μl) administered i.t. did not affect the blood glucose level. Baclofen-induced elevation of the blood glucose was dose-dependently attenuated by phaclofen. Furthermore, i.t. pretreatment with pertussis toxin (PTX; 0.05 or 0.1 μg/5 μl) for 6 days dose-dependently reduced the hyperglycemic effect induced by baclofen. Our results suggest that GABAB receptors located in the spinal cord play important roles for the elevation of the blood glucose level. Spinally located PTX-sensitive G-proteins appear to be involved in hyperglycemic effect induced by baclofen. Furthermore, inactivation of GABAA receptors located in the spinal cord appears to be responsible for tonic up-regulation of the blood glucose level.

  1. In vitro binding and receptor-mediated activity of terlipressin at vasopressin receptors V1 and V2.

    Science.gov (United States)

    Jamil, Khurram; Pappas, Stephen Chris; Devarakonda, Krishna R

    2018-01-01

    Terlipressin, a synthetic, systemic vasoconstrictor with selective activity at vasopressin-1 (V 1 ) receptors, is a pro-drug for the endogenous/natural porcine hormone [Lys 8 ]-vasopressin (LVP). We investigated binding and receptor-mediated cellular activities of terlipressin, LVP, and endogenous human hormone [Arg 8 ]-vasopressin (AVP) at V 1 and vasopressin-2 (V 2 ) receptors. Cell membrane homogenates of Chinese hamster ovary cells expressing human V 1 and V 2 receptors were used in competitive binding assays to measure receptor-binding activity. These cells were used in functional assays to measure receptor-mediated cellular activity of terlipressin, LVP, and AVP. Binding was measured by [ 3 H]AVP counts, and the activity was measured by fluorometric detection of intracellular calcium mobilization (V 1 ) and cyclic adenosine monophosphate (V 2 ). Binding potency at V 1 and V 2 was AVP>LVP>terlipressin. LVP and terlipressin had approximately sixfold higher affinity for V 1 than for V 2 . Cellular activity potency was also AVP>LVP>terlipressin. Terlipressin was a partial agonist at V 1 and a full agonist at V 2 ; LVP was a full agonist at both V 1 and V 2 . The in vivo response to terlipressin is likely due to the partial V 1 agonist activity of terlipressin and full V 1 agonist activity of its metabolite, LVP. These results provide supportive evidence for previous findings and further establish terlipressin pharmacology for vasopressin receptors.

  2. Glucagon-like peptide-1 receptor agonists for the treatment of type 2 diabetes

    DEFF Research Database (Denmark)

    Lund, Asger; Knop, Filip K; Vilsbøll, Tina

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone, secreted in response to ingestion of nutrients, and has important effects on several of the pathophysiological features of type 2 diabetes (T2D). The effects include potentiation of insulin secretion, suppression of glucagon secretion...... effects. This review gives an overview of the clinical data on GLP-1R agonists that have been compared in head-to-head studies and focuses on relevant differences between the compounds. Highlighting these similarities and differences could be beneficial for physicians in choosing the best treatment......, slowing of gastric emptying and suppression of appetite. In circulation, GLP-1 has a half-life of approximately 2min due to rapid degradation by the enzyme dipeptidyl peptidase 4 (DPP-4). Because of this short half-life GLP-1 receptor (GLP-1R) agonists, resistant to degradation by DPP-4 have been...

  3. Progress in the development of histamine H3 receptor antagonists/inverse agonists: a patent review (2013-2017).

    Science.gov (United States)

    Łażewska, Dorota; Kieć-Kononowicz, Katarzyna

    2018-03-01

    Since years, ligands blocking histamine H 3 receptor (H 3 R) activity (antagonists/inverse agonists) are interesting targets in the search for new cures for CNS disorders. Intensive works done by academic and pharmaceutical company researchers have led to many potent and selective H 3 R antagonists/inverse agonists. Some of them have reached to clinical trials. Areas covered: Patent applications from January 2013 to September 2017 and the most important topics connected with H 3 R field are analysed. Espacenet, Patentscope, Pubmed, GoogleScholar or Cochrane Library online databases were principially used to collect all the materials. Expert opinion: The research interest in histamine H 3 R field is still high although the number of patent applications has decreased during the past 4 years (around 20 publications). Complexity of histamine H 3 R biology e.g. many isoforms, constitutive activity, heteromerization with other receptors (dopamine D 2 , D 1 , adenosine A 2A ) and pharmacology make not easy realization and evaluation of therapeutic potential of anti-H 3 R ligands. First results from clinical trials have verified potential utility of histamine H 3 R antagonist/inverse agonists in some diseases. However, more studies are necessary for better understanding of an involvement of the histaminergic system in CNS-related disorders and helping more ligands approach to clinical trials and the market. Lists of abbreviations: hAChEI - human acetylcholinesterase inhibitor; hBuChEI - human butyrylcholinesterase inhibitor; hMAO - human monoamine oxidase; MAO - monoamine oxidase.

  4. Agonistic effects of a monoclonal antibody specific for the interleukin-2 receptor

    International Nuclear Information System (INIS)

    Eardley, D.D.; Makrides, V.

    1986-01-01

    Interleukin-2 (IL-2) mediated immune responses can be blocked by monoclonal antibodies to the IL-2 receptor. The monoclonal antibody, M720, is defined as specific for the IL-2 receptor because it blocks 35 S-IL-2 binding to Con A blasts, reacts with lymphoblasts but not resting splenocytes, and inhibits IL-2 induced proliferation to mitogen, antigen, or allogeneic stimuli. Under appropriate culture conditions, the IL-2 receptor-specific antibody can act like IL-2 in that it will induce proliferation in T cells in the absence of additional antigen or mitogen. This agonistic effect is dependent on time, dose of antibody, and requires fetal calf serum (FCS) in the media. Because the FCS is not mitogenic by itself, the authors propose that the FCS components act as incomplete mitogen to induce appearance of IL-2 receptors but lack a factor which would push the majority of the cells into the S phase of the cell cycle. This factor is usually IL-2, but in the authors experiments, the IL-2 receptor-specific antibody can provide the same stimulus. These data indicate that factors like FCS can induce IL-2 receptors, but without additional IL-2 or receptor triggering, the cells will not proceed through the synthetic and proliferative phases of cell growth

  5. The effects of the alpha2-adrenergic receptor agonists clonidine and rilmenidine, and antagonists yohimbine and efaroxan, on the spinal cholinergic receptor system in the rat

    DEFF Research Database (Denmark)

    Abelson, Klas S P; Höglund, A Urban

    2004-01-01

    Cholinergic agonists produce spinal antinociception via mechanisms involving an increased release of intraspinal acetylcholine. The cholinergic receptor system interacts with several other receptor types, such as alpha2-adrenergic receptors. To fully understand these interactions, the effects...... of various receptor ligands on the cholinergic system must be investigated in detail. This study was initiated to investigate the effects of the alpha2-adrenergic receptor agonists clonidine and rilmenidine and the alpha2-adrenergic receptor antagonists yohimbine and efaroxan on spinal cholinergic receptors......, all ligands possessed affinity for nicotinic receptors. Clonidine and yohimbine binding was best fit to a one site binding curve and rilmenidine and efaroxan to a two site binding curve. The present study demonstrates that the tested alpha2-adrenergic receptor ligands affect intraspinal acetylcholine...

  6. In vitro screening for aryl hydrocarbon receptor agonistic activity in 200 pesticides using a highly sensitive reporter cell line, DR-EcoScreen cells, and in vivo mouse liver cytochrome P450-1A induction by propanil, diuron and linuron.

    Science.gov (United States)

    Takeuchi, Shinji; Iida, Mitsuru; Yabushita, Hisatoshi; Matsuda, Tadashi; Kojima, Hiroyuki

    2008-12-01

    The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that regulates genes involved in xenobiotic metabolism, cellular proliferation and differentiation. In this study, we have developed a highly sensitive AhR-mediated reporter cell line, DR-EcoScreen cells, which are mouse hepatoma Hepa1c1c7 cells stably transfected with a reporter plasmid containing seven copies of dioxin-responsive element. Using these DR-EcoScreen cells, we performed the reporter gene assay and characterized the AhR agonistic activities of 200 pesticides (29 organochlorines, 11 diphenyl ethers, 56 organophosphorus pesticides, 12 pyrethroids, 22 carbamates, 12 acid amides, 7 triazines, 6 ureas, and 45 others). Eleven of the 200 pesticides (acifluorfen-methyl, bifenox, chlorpyrifos, isoxathion, quinalphos, chlorpropham, diethofencarb, propanil, diuron, linuron, and prochloraz) showed AhR-mediated transcriptional activity. In particular, three herbicides (propanil, diuron, and linuron) have a common chemical structure and showed more potent agonistic activity than other pesticides. To investigate the in vivo effects, we examined the gene expression of AhR-inducible cytochrome P450 1As (CYP1As) in the liver of female C57BL/6 mice intraperitoneally injected with these three herbicides (300 mg kg(-1)) by quantitative RT-PCR, resulting in induction of significant high levels of CYP1A1 and CYP1A2 mRNAs. This indicates that propanil, diuron and linuron possess AhR-mediated transactivation effect in vivo as well as in vitro. Through the present study, we demonstrated that DR-EcoScreen cells are useful for sensitive, rapid and simple identification of AhR agonists among a large number of environmental chemicals.

  7. PPARγ agonist pioglitazone reduces matrix metalloproteinase-9 activity and neuronal damage after focal cerebral ischemia

    International Nuclear Information System (INIS)

    Lee, Seong-Ryong; Kim, Hahn-Young; Hong, Jung-Suk; Baek, Won-Ki; Park, Jong-Wook

    2009-01-01

    Pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, has shown protective effects against ischemic insult in various tissues. Pioglitazone is also reported to reduce matrix metalloproteinase (MMP) activity. MMPs can remodel extracellular matrix components in many pathological conditions. The current study was designed to investigate whether the neuroprotection of pioglitazone is related to its MMP inhibition in focal cerebral ischemia. Mice were subjected to 90 min focal ischemia and reperfusion. In gel zymography, pioglitazone reduced the upregulation of active form of MMP-9 after ischemia. In in situ zymograms, pioglitazone also reduced the gelatinase activity induced by ischemia. After co-incubation with pioglitazone, in situ gelatinase activity was directly reduced. Pioglitazone reduced the infarct volume significantly compared with controls. These results demonstrate that pioglitazone may reduce MMP-9 activity and neuronal damage following focal ischemia. The reduction of MMP-9 activity may have a possible therapeutic effect for the management of brain injury after focal ischemia.

  8. Quinuclidine compounds differently act as agonists of Kenyon cell nicotinic acetylcholine receptors and induced distinct effect on insect ganglionic depolarizations.

    Science.gov (United States)

    Mathé-Allainmat, Monique; Swale, Daniel; Leray, Xavier; Benzidane, Yassine; Lebreton, Jacques; Bloomquist, Jeffrey R; Thany, Steeve H

    2013-12-01

    We have recently demonstrated that a new quinuclidine benzamide compound named LMA10203 acted as an agonist of insect nicotinic acetylcholine receptors. Its specific pharmacological profile on cockroach dorsal unpaired median neurons (DUM) helped to identify alpha-bungarotoxin-insensitive nAChR2 receptors. In the present study, we tested its effect on cockroach Kenyon cells. We found that it induced an inward current demonstrating that it bounds to nicotinic acetylcholine receptors expressed on Kenyon cells. Interestingly, LMA10203-induced currents were completely blocked by the nicotinic antagonist α-bungarotoxin. We suggested that LMA10203 effect occurred through the activation of α-bungarotoxin-sensitive receptors and did not involve α-bungarotoxin-insensitive nAChR2, previously identified in DUM neurons. In addition, we have synthesized two new compounds, LMA10210 and LMA10211, and compared their effects on Kenyon cells. These compounds were members of the 3-quinuclidinyl benzamide or benzoate families. Interestingly, 1 mM LMA10210 was not able to induce an inward current on Kenyon cells compared to LMA10211. Similarly, we did not find any significant effect of LMA10210 on cockroach ganglionic depolarization, whereas these three compounds were able to induce an effect on the central nervous system of the third instar M. domestica larvae. Our data suggested that these three compounds could bind to distinct cockroach nicotinic acetylcholine receptors.

  9. The α4β2 nicotine acetylcholine receptor agonist ispronicline induces c-Fos expression in selective regions of the rat forebrain

    DEFF Research Database (Denmark)

    Jacobsen, Julie; Hansen, Henrik H; Kiss, Alexander

    2012-01-01

    The dominant nicotine acetylcholine receptor (nAChR) subtype in the brain is the pentameric receptor containing both α4 and β2 subunits (α4β2). Due to the lack of selective agonists it has not been ruled out what neuronal circuits that are stimulated after systemic administration with nicotine. We...... or indirectly involved in acute stress regulation after a single dose of ispronicline, supports earlier studies that the α4β2 receptors are strongly involved in nicotine-dependent activation of the hypothalamo-pituitary adrenocortical axis....

  10. RM-493, a melanocortin-4 receptor (MC4R) agonist, increases resting energy expenditure in obese individuals.

    Science.gov (United States)

    Chen, Kong Y; Muniyappa, Ranganath; Abel, Brent S; Mullins, Katherine P; Staker, Pamela; Brychta, Robert J; Zhao, Xiongce; Ring, Michael; Psota, Tricia L; Cone, Roger D; Panaro, Brandon L; Gottesdiener, Keith M; Van der Ploeg, Lex H T; Reitman, Marc L; Skarulis, Monica C

    2015-04-01

    Activation of the melanocortin-4 receptor (MC4R) with the synthetic agonist RM-493 decreases body weight and increases energy expenditure (EE) in nonhuman primates. The effects of MC4R agonists on EE in humans have not been examined to date. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effects of the MC4R agonist RM-493 on resting energy expenditure (REE) in obese subjects in an inpatient setting. Twelve healthy adults (6 men and 6 women) with body mass index of 35.7 ± 2.9 kg/m(2) (mean ± SD) received RM-493 (1 mg/24 h) or placebo by continuous subcutaneous infusion over 72 hours, followed immediately by crossover to the alternate treatment. All subjects received a weight-maintenance diet (50% carbohydrate, 30% fat, and 20% protein) and performed 30 minutes of standardized exercise daily. Continuous EE was measured on the third treatment day in a room calorimeter, and REE in the fasting state was defined as the mean of 2 30-minute resting periods. RM-493 increased REE vs placebo by 6.4% (95% confidence interval, 0.68-13.02%), on average by 111 kcal/24 h (95% confidence interval, 15-207 kcal, P = .03). Total daily EE trended higher, whereas the thermic effect of a test meal and exercise EE did not differ significantly. The 23-hour nonexercise respiratory quotient was lower during RM-493 treatment (0.833 ± 0.021 vs 0.848 ± 0.022, P = .02). No adverse effect on heart rate or blood pressure was observed. Short-term administration of the MC4R agonist RM-493 increases REE and shifts substrate oxidation to fat in obese individuals.

  11. FXR agonist activity of conformationally constrained analogs of GW 4064.

    Science.gov (United States)

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Bruce Wisely, G

    2009-08-15

    Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

  12. Characteristics in Molecular Vibrational Frequency Patterns between Agonists and Antagonists of Histamine Receptors

    Directory of Open Access Journals (Sweden)

    S. June Oh

    2012-06-01

    Full Text Available To learn the differences between the structure-activity relationship and molecular vibration-activity relationship in the ligand-receptor interaction of the histamine receptor, 47 ligands of the histamine receptor were analyzed by structural similarity and molecular vibrational frequency patterns. The radial tree that was produced by clustering analysis of molecular vibrational frequency patterns shows its potential for the functional classification of histamine receptor ligands.

  13. Unsaturated free fatty acids increase benzodiazepine receptor agonist binding depending on the subunit composition of the GABAA receptor complex.

    Science.gov (United States)

    Witt, M R; Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nielsen, M

    1996-11-01

    It has been shown previously that unsaturated free fatty acids (FFAs) strongly enhance the binding of agonist benzodiazepine receptor ligands and GABAA receptor ligands in the CNS in vitro. To investigate the selectivity of this effect, recombinant human GABAA/benzodiazepine receptor complexes formed by different subunit compositions (alpha x beta y gamma 2, x = 1, 2, 3, and 5; y = 1, 2, and 3) were expressed using the baculovirus-transfected Sf9 insect cell system. At 10(-4) M, unsaturated FFAs, particularly arachidonic (20:4) and docosahexaenoic (22:6) acids, strongly stimulated (> 200% of control values) the binding of [3H]flunitrazepam ([3H]FNM) to the alpha 3 beta 2 gamma 2 receptor combination in whole cell preparations. No effect or small increases in levels of unsaturated FFAs on [3H]FNM binding to alpha 1 beta x gamma 2 and alpha 2 beta x gamma 2 receptor combinations were observed, and weak effects (130% of control values) were detected using the alpha 5 beta 2 gamma 2 receptor combination. The saturated FFAs, stearic and palmitic acids, were without effect on [3H]FNM binding to any combination of receptor complexes. The hydroxylated unsaturated FFAs, ricinoleic and ricinelaidic acids, were shown to decrease the binding of [3H]FNM only if an alpha 1 beta 2 gamma 2 receptor combination was used. Given the heterogeneity of the GABAA/ benzodiazepine receptor subunit distribution in the CNS, the effects of FFAs on the benzodiazepine receptor can be assumed to vary at both cellular and regional levels.

  14. The effect of various opiate receptor agonists on the seizure threshold in the rat. Is dynorphin an endogenous anticonvulsant?

    Science.gov (United States)

    Przewłocka, B; Stala, L; Lasoń, W; Przewłocki, R

    1983-01-01

    The effects of various opiate receptor agonists on the seizure threshold after an intravenous infusion of pentylenetetrazol were investigated in rats. The mu- and epsilon-receptor agonists, morphine (20-40 micrograms) and beta-endorphin (5-10 micrograms) show proconvulsant properties towards clonic and tonic seizures. The delta-receptor agonist (D-Ala2,D-Leu5-enkephalin, DADL 5-40 micrograms) and alpha-neoendorphin (20-40 micrograms) show pro- and anticonvulsant properties towards clonic and tonic seizures, respectively. Anticonvulsant properties of DADL are possibly due to its action on the spinal cord, since after the intrathecal injection this effect is still observed. Similarities between DADL and alpha-neoendorphin suggest that they may act through the same receptor. The kappa-receptor agonist dynorphin A (5-20 micrograms) and its degradation-resistant analogue D-Arg-dynorphin1-13 (10 micrograms) show significant anticonvulsant properties. Our present results suggest that the kappa-receptor agonist dynorphin may act physiologically as an endogenous anticonvulsant, in contrast to other opioid peptides.

  15. Structural and energetic effects of A2A adenosine receptor mutations on agonist and antagonist binding.

    Directory of Open Access Journals (Sweden)

    Henrik Keränen

    Full Text Available To predict structural and energetic effects of point mutations on ligand binding is of considerable interest in biochemistry and pharmacology. This is not only useful in connection with site-directed mutagenesis experiments, but could also allow interpretation and prediction of individual responses to drug treatment. For G-protein coupled receptors systematic mutagenesis has provided the major part of functional data as structural information until recently has been very limited. For the pharmacologically important A(2A adenosine receptor, extensive site-directed mutagenesis data on agonist and antagonist binding is available and crystal structures of both types of complexes have been determined. Here, we employ a computational strategy, based on molecular dynamics free energy simulations, to rationalize and interpret available alanine-scanning experiments for both agonist and antagonist binding to this receptor. These computer simulations show excellent agreement with the experimental data and, most importantly, reveal the molecular details behind the observed effects which are often not immediately evident from the crystal structures. The work further provides a distinct validation of the computational strategy used to assess effects of point-mutations on ligand binding. It also highlights the importance of considering not only protein-ligand interactions but also those mediated by solvent water molecules, in ligand design projects.

  16. Palovarotene, a novel retinoic acid receptor gamma agonist for the treatment of emphysema.

    Science.gov (United States)

    Hind, Matthew; Stinchcombe, Sian

    2009-11-01

    Emphysema is characterized by the destruction of alveoli and alveolar ducts within the lungs. Retinoid signaling is believed to play a role in alveologenesis, with the retinoic acid receptor gamma thought to be required for alveolar formation. Based on this hypothesis, Roche Holding AG is developing palovarotene (R-667, RO-3300074), a selective retinoic acid receptor gamma agonist for the treatment of emphysema. In small animal studies, palovarotene was claimed to reverse the structural, functional and inflammatory features of cigarette smoke-induced emphysema. Phase I clinical trials of palovarotene in patients with emphysema demonstrated that the drug is well tolerated, with improvements observed in markers of emphysema progression. Unlike all-trans retinoic acid, the pharmacokinetic profile of palovarotene appears to be dose-proportional. At the time of publication, a phase II, placebo-controlled trial was ongoing, and was expected to report prospective measurements of exercise, gas transfer and lung densitometry endpoints. The development of a selective retinoic acid receptor gamma agonist for the treatment of emphysema represents the first of a new class of small-molecule regenerative therapies that may prove useful for the treatment of destructive or age-related lung disease.

  17. Studies To Examine Potential Tolerability Differences between the 5-HT2C Receptor Selective Agonists Lorcaserin and CP-809101.

    Science.gov (United States)

    Higgins, Guy A; Silenieks, Leonardo B; Patrick, Amy; De Lannoy, Ines A M; Fletcher, Paul J; Parker, Linda A; MacLusky, Neil J; Sullivan, Laura C; Chavera, Teresa A; Berg, Kelly A

    2017-05-17

    Lorcaserin (LOR) is a selective 5-HT 2C receptor agonist that has been FDA approved as a treatment for obesity. The most frequently reported side-effects of LOR include nausea and headache, which can be dose limiting. We have previously reported that in the rat, while LOR produced unconditioned signs characteristic of nausea/malaise, the highly selective 5-HT 2C agonist CP-809101 (CP) produced fewer equivalent signs. Because this may indicate a subclass of 5-HT 2C agonists having better tolerability, the present studies were designed to further investigate this apparent difference. In a conditioned gaping model, a rodent test of nausea, LOR produced significantly higher gapes compared to CP consistent with it having higher emetogenic properties. Subsequent studies were designed to identify features of each drug that may account for such differences. In rats trained to discriminate CP-809101 from saline, both CP and LOR produced full generalization suggesting a similar interoceptive cue. In vitro tests of functional selectivity designed to examine signaling pathways activated by both drugs in CHO (Chinese hamster ovary) cells expressing h5-HT 2C receptors failed to identify evidence for biased signaling differences between LOR and CP. Thus, both drugs showed similar profiles across PLC, PLA 2 , and ERK signaling pathways. In studies designed to examine pharmacokinetic differences between LOR and CP, while drug plasma levels correlated with increasing dose, CSF levels did not. CSF levels of LOR increased proportionally with dose; however CSF levels of CP plateaued from 6 to 12 mg/kg. Thus, the apparently improved tolerability of CP likely reflects a limit to CNS levels attained at relatively high doses.

  18. The effects of benzodiazepine-receptor antagonists and partial inverse agonists on acute hepatic encephalopathy in the rat

    NARCIS (Netherlands)

    Bosman, D. K.; van den Buijs, C. A.; de Haan, J. G.; Maas, M. A.; Chamuleau, R. A.

    1991-01-01

    Two benzodiazepine-receptor partial inverse agonists (Ro 15-4513, Ro 15-3505) and one benzodiazepine-receptor antagonist (flumazenil) were administered to rats with hepatic encephalopathy due to acute liver ischemia. Significant improvement (P less than 0.002) of both the clinical grade of hepatic

  19. Preventing or attenuating amphotericin B nephrotoxicity with dopamine receptor agonists: a literature review

    Directory of Open Access Journals (Sweden)

    Iman Karimzadeh

    2016-09-01

    Full Text Available Nephrotoxicity is generally considered as the most clinically significant and dose-limiting adverse reaction of amphotericin B. Currently, only the clinical effectiveness of salt loading and administering lipid formulations of amphotericin B have been clearly demonstrated to prevent its nephrotoxicity. In this review, we collected the published data related to dopamine receptor agonists in preventing amphotericin B nephrotoxicity. A literature search was conducted by the relevant keywords like ‘‘amphotericin B”, “nephrotoxicity’’, and ‘‘dopamine’’in databases such as Scopus, Medline, Embase and ISI Web of Knowledge. Four relevant articles were considered. Results of all the 3 experimental studies demonstrated that co-administration of dopamine (0.5-10 μg/kg/min as continuous intravenous infusion, SK&F R-105058, a prodrug of fenoldopam (10 mg/kg twice daily, orally or fenoldopam, a relatively selective dopamine receptor type 1 agonist, (0.5 or 1 μg/kg/min as continuous intravenous infusion can at least significantly mitigate the decrease in creatinine clearance caused by amphotericin B. Furthermore, fenoldopam and SK&F R-105058 can also protect against or delay amphotericin B-induced tubular damage. In contrast, the only clinical trial published until now found that simultaneous continuous intravenous infusion of low dose dopamine (3 μg/kg/min had no beneficial effect on the incidence, severity and time onset of developing amphotericin B-induced nephrotoxicity in autologous bone marrow transplant and leukemia patients. Considering the lack of beneficial effects in different settings such as acute kidney injury of any cause, negative results of the only clinical trial, and risk of significant adverse reactions, continuous intravenous infusion of low dose dopamine (1-3 μg/kg/min or selective dopamine receptor type 1 agonists (e.g., fenoldopam currently appears to have no promising clinical role in preventing or attenuating

  20. Potent μ-Opioid Receptor Agonists from Cyclic Peptides Tyr-c[D-Lys-Xxx-Tyr-Gly]: Synthesis, Biological, and Structural Evaluation.

    Science.gov (United States)

    Li, Yangmei; Cazares, Margret; Wu, Jinhua; Houghten, Richard A; Toll, Laurence; Dooley, Colette

    2016-02-11

    To optimize the structure of a μ-opioid receptor ligand, analogs H-Tyr-c[D-Lys-Xxx-Tyr-Gly] were synthesized and their biological activity was tested. The analog containing a Phe(3) was identified as not only exhibiting binding affinity 14-fold higher than the original hit but also producing agonist activity 3-fold more potent than morphine. NMR study suggested that a trans conformation at D-Lys(2)-Xxx(3) is crucial for these cyclic peptides to maintain high affinity, selectivity, and functional activity toward the μ-opioid receptor.

  1. Agonist-dependent modulation of G-protein coupling and transduction of 5-HT1A receptors in rat dorsal raphe nucleus

    OpenAIRE

    Valdizán, Elsa M.; Castro, Elena; Pazos, Ángel

    2009-01-01

    5-HT1A receptors couple to different Go/Gi proteins in order to mediate a wide range of physiological actions. While activation of post-synaptic 5-HT1A receptors is mainly related to inhibition of adenylyl cyclase activity, functionality of autoreceptors located in raphe nuclei has been classically ascribed to modifications of the activity of potassium and calcium channels. In order to evaluate the possible existence of agonist-directed trafficking for 5-HT1A autoreceptors in the rat dorsal r...

  2. Synthesis and evaluation of 18F-labeled 5-HT2A receptor agonists as PET ligands

    International Nuclear Information System (INIS)

    Herth, Matthias M.; Petersen, Ida Nymann; Hansen, Hanne Demant; Hansen, Martin; Ettrup, Anders; Jensen, Anders A.; Lehel, Szabolcs; Dyssegaard, Agnete; Gillings, Nic; Knudsen, Gitte M.

    2016-01-01

    Introduction: The serotonin 2A receptor (5-HT 2A R) is the most abundant excitatory 5-HT receptor in the human brain and implicated in various brain disorders such as schizophrenia, depression, and Alzheimer's disease. Positron emission tomography (PET) can be used to image specific proteins and processes in the human brain and several 5-HT 2A R PET antagonist radioligands are available. In contrast to an antagonist radioligand, an agonist radioligand should be able to image the population of functional receptors, i.e., those capable of inducing neuroreceptor signaling. Recently, we successfully developed and validated the first 5-HT 2A R agonist PET tracer, [ 11 C]Cimbi-36, for neuroimaging in humans and herein disclose some of our efforts to develop an 18 F-labeled 5-HT 2A R agonist PET-ligand. Methods and results: Three fluorine containing derivatives of Cimbi-36 were synthesized and found to be potent 5-HT 2A agonists. 18 F-labeling of the appropriate precursors was performed using [ 18 F]FETos, typically yielding 0.2–2.0 GBq and specific activities of 40–120 GBq/μmol. PET studies in Danish landrace pigs revealed that [ 18 F]1 displayed brain uptake in 5-HT 2A R rich regions. However, high uptake in bone was also observed. No blocking effect was detected during a competition experiment with a 5-HT 2A R selective antagonist. [ 18 F]2 and [ 18 F]3 showed very low brain uptake. Conclusion: None of the investigated 18 F-labeled Cimbi-36 derivatives [ 18 F]1, [ 18 F]2 and [ 18 F]3 show suitable tracer characteristics for in vivo PET neuroimaging of the 5-HT 2A R. Although for [ 18 F]1 there was reasonable brain uptake, we suggest that a large proportion radioactivity in the brain was due to radiometabolites, which would explain why it could not be displaced by a 5-HT 2A R antagonist.

  3. Metal ion-mediated agonism and agonist enhancement in melanocortin MC1 and MC4 receptors

    DEFF Research Database (Denmark)

    Holst, Birgitte; Elling, Christian E; Schwartz, Thue W

    2002-01-01

    -melanocortin stimulating hormone (alpha-MSH) in the MC1 and MC4 receptors, respectively. In the presence of peptide agonist, Zn(II) acted as an enhancer on both receptors, because it shifted the dose-response curves to the left: most pronounced was a 6-fold increase in alpha-MSH potency on the MC1 receptor. The effect......An endogenous metal-ion site in the melanocortin MC1 and MC4 receptors was characterized mainly in transiently transfected COS-7 cells. ZnCl(2) alone stimulated signaling through the Gs pathway with a potency of 11 and 13 microm and an efficacy of 50 and 20% of that of alpha...... affinities and profiles were similar for a number of the 2,2'-bipyridine and 1,10-phenanthroline analogs in complex with Zn(II) in the MC1 and MC4 receptors. However, the potencies and efficacies of the metal-ion complexes were very different in the two receptors, and close to full agonism was obtained...

  4. Evidence that the angiotensin at 2-receptor agonist compound 21 is also a low affinity thromboxane TXA2-receptor antagonist

    DEFF Research Database (Denmark)

    Fredgart, M.; Leurgans, T.; Stenelo, M.

    2015-01-01

    Objective: The objective of this study was to test whether Compound 21 (C21), a high-affinity, non-peptide angiotensinAT2-receptor agonist, is also an antagonist of thromboxane A2 (TXA2) receptors thus reducing both vasoconstriction and platelet aggregation. Design and method: Binding of C21...... to the TXA2 receptor was determined by TBXA2R Arrestin Biosensor Assay. Mouse mesenteric arteries were mounted in wire myographs, and responses to increasing concentrations of C21 (1nM- 10muM) were recorded during submaximal contractions with 0.1muM U46619 (TXA2 analogue) or 1muMphenylephrine. To control for......AT2-receptor specificity, arteries were pre-incubated with the AT2-receptor antagonist PD123319 (10muM), or mesenteric arteries from AT2-receptor knock-out (AT2R-/y) mice were used. An inhibitory effect of C21 (100nM - 10muM) on U46619 (0,3muM) induced platelet aggregation was examined in whole human...

  5. Molecular interactions of agonist and inverse agonist ligands at serotonin 5-HT2C G protein-coupled receptors: computational ligand docking and molecular dynamics studies validated by experimental mutagenesis results

    Science.gov (United States)

    Córdova-Sintjago, Tania C.; Liu, Yue; Booth, Raymond G.

    2015-02-01

    To understand molecular determinants for ligand activation of the serotonin 5-HT2C G protein-coupled receptor (GPCR), a drug target for obesity and neuropsychiatric disorders, a 5-HT2C homology model was built according to an adrenergic β2 GPCR (β2AR) structure and validated using a 5-HT2B GPCR crystal structure. The models were equilibrated in a simulated phosphatidyl choline membrane for ligand docking and molecular dynamics studies. Ligands included (2S, 4R)-(-)-trans-4-(3'-bromo- and trifluoro-phenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalene-2-amine (3'-Br-PAT and 3'-CF3-PAT), a 5-HT2C agonist and inverse agonist, respectively. Distinct interactions of 3'-Br-PAT and 3'-CF3-PAT at the wild-type (WT) 5-HT2C receptor model were observed and experimental 5-HT2C receptor mutagenesis studies were undertaken to validate the modelling results. For example, the inverse agonist 3'-CF3-PAT docked deeper in the WT 5-HT2C binding pocket and altered the orientation of transmembrane helices (TM) 6 in comparison to the agonist 3'-Br-PAT, suggesting that changes in TM orientation that result from ligand binding impact function. For both PATs, mutation of 5-HT2C residues S3.36, T3.37, and F5.47 to alanine resulted in significantly decreased affinity, as predicted from modelling results. It was concluded that upon PAT binding, 5-HT2C residues T3.37 and F5.47 in TMs 3 and 5, respectively, engage in inter-helical interactions with TMs 4 and 6, respectively. The movement of TMs 5 and 6 upon agonist and inverse agonist ligand binding observed in the 5-HT2C receptor modelling studies was similar to movements reported for the activation and deactivation of the β2AR, suggesting common mechanisms among aminergic neurotransmitter GPCRs.

  6. Treatment of type 2 diabetes by free Fatty Acid receptor agonists

    DEFF Research Database (Denmark)

    Watterson, Kenneth R; Hudson, Brian D; Ulven, Trond

    2014-01-01

    been developed as potential treatments for type 2 diabetes (T2D). In particular, clinical studies show that Fasiglifam, an agonist of the long-chain FFA receptor, FFA1, improved glycemic control and reduced HbA1c levels in T2D patients, with a reduced risk of hypoglycemia. However, this ligand...... was removed from clinical trials due to potential liver toxicity and determining if this is a target or a ligand-specific feature is now of major importance. Pre-clinical studies also show that FFA4 agonism increases insulin sensitivity, induces weight loss, and reduces inflammation and the metabolic and anti...

  7. The melatonin receptor agonist ramelteon effectively treats insomnia and behavioral symptoms in autistic disorder.

    Science.gov (United States)

    Kawabe, Kentaro; Horiuchi, Fumie; Oka, Yasunori; Ueno, Shu-Ichi

    2014-01-01

    Children with autism spectrum disorders (ASD), including autistic disorder, frequently suffer from comorbid sleep problems. An altered melatonin rhythm is considered to underlie the impairment in sleep onset and maintenance in ASD. We report three cases with autistic disorder in whom nocturnal symptoms improved with ramelteon, a selective melatonin receptor agonist. Insomnia and behavior, assessed using the Clinical Global Impression-Improvement Scale, improved in two cases with 2 mg ramelteon and in the third case with 8 mg ramelteon. Our findings demonstrate that ramelteon is effective not only for insomnia, but for behavioral problems as well, in patients with autistic disorder.

  8. Anxiogenic properties of an inverse agonist selective for α3 subunit-containing GABAA receptors

    OpenAIRE

    Atack, John R; Hutson, Peter H; Collinson, Neil; Marshall, George; Bentley, Graham; Moyes, Christopher; Cook, Susan M; Collins, Ian; Wafford, Keith; McKernan, Ruth M; Dawson, Gerard R

    2005-01-01

    α3IA (6-(4-pyridyl)-5-(4-methoxyphenyl)-3-carbomethoxy-1-methyl-1H-pyridin-2-one) is a pyridone with higher binding and functional affinity and greater inverse agonist efficacy for GABAA receptors containing an α3 rather than an α1, α2 or α5 subunit. If doses are selected that minimise the occupancy at these latter subtypes, then the in vivo effects of α3IA are most probably mediated by the α3 subtype.α3IA has good CNS penetration in rats and mice as measured using a [3H]Ro 15-1788 in vivo bi...

  9. Melatonin Receptor Agonists as the “Perioceutics” Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response

    Science.gov (United States)

    Zhu, Cai-Lian; He, Zhi-Yan; Liang, Jing-Ping; Song, Zhong-Chen

    2016-01-01

    Aim “Perioceutics” including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential “perioceutics” treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation. Methods Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA). Results Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence

  10. Agonist-dependent modulation of G-protein coupling and transduction of 5-HT1A receptors in rat dorsal raphe nucleus.

    Science.gov (United States)

    Valdizán, Elsa Maria; Castro, Elena; Pazos, Angel

    2010-08-01

    5-HT1A receptors couple to different Go/Gi proteins in order to mediate a wide range of physiological actions. While activation of post-synaptic 5-HT1A receptors is mainly related to inhibition of adenylyl cyclase activity, functionality of autoreceptors located in raphe nuclei has been classically ascribed to modifications of the activity of potassium and calcium channels. In order to evaluate the possible existence of agonist-directed trafficking for 5-HT1A autoreceptors in the rat dorsal raphe nucleus, we studied their activation by two agonists with a different profile of efficacy [(+)8-OH-DPAT and buspirone], addressing simultaneously the identification of the specific Galpha subtypes ([35S]GTPgammaS labelling and immunoprecipitation) involved and the subsequent changes in cAMP formation. A significant increase (32%, plabelling of immunoprecipitates was obtained with anti-Galphai3 antibodies but not with anti-Galphao, anti-Galphai1, anti-Galphai2, anti-Galphaz or anti-Galphas antibodies. In contrast, in the presence of buspirone, significant [35S]GTPgammaS labelling of immunoprecipitates was obtained with anti-Galphai3 (50%, plabelling with anti-Galphai1, anti-Galphaz or anti-Galphas. The selective 5-HT1A antagonist WAY 100635 blocked the labelling induced by both agonists. Furthermore, (+)8-OH-DPAT failed to modify forskolin-stimulated cAMP accumulation, while buspirone induced a dose-dependent, WAY 100635-sensitive, inhibition of this response (Imax 30.8+/-4.9, pIC50 5.95+/-0.46). These results demonstrate the existence of an agonist-dependency pattern of G-protein coupling and transduction for 5-HT1A autoreceptors in native brain tissue. These data also open new perspectives for the understanding of the differential profiles of agonist efficacy in pre- vs. post-synaptic 5-HT1A receptor-associated responses.

  11. The acute effect of a mineralocorticoid receptor agonist on corticotrope secretion in Addison's disease.

    Science.gov (United States)

    Berardelli, R; Karamouzis, I; D'Angelo, V; Fussotto, B; Minetto, M A; Ghigo, E; Giordano, R; Arvat, E

    2016-05-01

    Mineralocorticoid receptors (MR) in the hippocampus display an important role in the control of hypothalamic-pituitary-adrenal (HPA) axis, mediating the ''proactive'' feedback of glucocorticoids (GC). Fludrocortisone (FC), a potent MR agonist, has been shown to decrease HPA activity through a hippocampal mechanism. Since it has been demonstrated that FC shows a significant inhibition of the HPA axis response to hCRH stimulus in normal subjects, also at doses usually administered as replacement therapy in patients with Addison's disease, an FC effect at MRs in human pituitary or a GR-pituitary agonism stronger than believed until now has been postulated. Ten patients affected by autoimmune Addison's disease received: (1) placebo p.o. + placebo i.v., (2) hydrocortisone (H) 10 mg p.o. + placebo i.v., (3) FC 0.1 mg p.o. + placebo i.v., (4) FC 0.1 mg and H 10 mg p.o. + placebo i.v. to verify a possible GR FC-mediated effect that might display a repercussion on the GC-replacement therapy. H reduced ACTH (p < 0.01) and increased cortisol levels (p < 0.01) with respect to the placebo session, while FC did not affect either ACTH or cortisol levels compared to placebo, and higher ACTH and lower cortisol levels (p < 0.03 and p < 0.01) were observed compared with the H session; furthermore the co-administration of FC + H showed ACTH and cortisol profiles similar to that observed during H alone. Our study showed a lack of FC effect on corticotrope secretion in Addison's disease, thus making unlikely the hypothesis of its GR pituitary agonism and the risk of glucocorticoid excess in primary adrenal insufficiency.

  12. Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists?

    Science.gov (United States)

    Hong, Seongjin; Lee, Junghyun; Lee, Changkeun; Yoon, Seo Joon; Jeon, Seungyeon; Kwon, Bong-Oh; Lee, Jong-Hyeon; Giesy, John P; Khim, Jong Seong

    2016-06-01

    Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g(-1) dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g(-1) dm) and outer regions (mean = 25 ng g(-1) dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (coastal environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Nanoparticles containing a liver X receptor agonist inhibit inflammation and atherosclerosis.

    Science.gov (United States)

    Zhang, Xue-Qing; Even-Or, Orli; Xu, Xiaoyang; van Rosmalen, Mariska; Lim, Lucas; Gadde, Suresh; Farokhzad, Omid C; Fisher, Edward A

    2015-01-28

    Liver X receptor (LXR) signaling pathways regulate lipid metabolism and inflammation, which has generated widespread interest in developing synthetic LXR agonists as potential therapeutics for the management of atherosclerosis. In this study, it is demonstrated that nanoparticles (NPs) containing the synthetic LXR agonist GW3965 (NP-LXR) exert anti-inflammatory effects and inhibit the development of atherosclerosis without causing hepatic steatosis. These NPs are engineered through self-assembly of a biodegradable diblock poly(lactide-co-glycolide)-b-poly(ethylene glycol) (PLGA-b-PEG) copolymer. NP-LXR is significantly more effective than free GW3965 at inducing LXR-target gene expression and suppressing inflammatory factors in macrophages in vitro and in vivo. Additionally, the NPs elicit negligible lipogenic gene stimulation in the liver. Using the Ldlr (-/-) mouse model of atherosclerosis, abundant colocalization of fluorescently labeled NPs within plaque macrophages following systemic administration is seen. Notably, six intravenous injections of NP-LXR over 2 weeks markedly reduce the CD68-positive cell (macrophage) content of plaques (by 50%) without increasing total cholesterol or triglycerides in the liver and plasma. Together, these findings identify GW3965-encapsulated PLGA-b-PEG NPs as a promising nanotherapeutic approach to combat atherosclerosis, providing the benefits of LXR agonists without their adverse effects on hepatic and plasma lipid metabolism. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Conformation guides molecular efficacy in docking screens of activated β-2 adrenergic G protein coupled receptor.

    Science.gov (United States)

    Weiss, Dahlia R; Ahn, SeungKirl; Sassano, Maria F; Kleist, Andrew; Zhu, Xiao; Strachan, Ryan; Roth, Bryan L; Lefkowitz, Robert J; Shoichet, Brian K

    2013-05-17

    A prospective, large library virtual screen against an activated β2-adrenergic receptor (β2AR) structure returned potent agonists to the exclusion of inverse-agonists, providing the first complement to the previous virtual screening campaigns against inverse-agonist-bound G protein coupled receptor (GPCR) structures, which predicted only inverse-agonists. In addition, two hits recapitulated the signaling profile of the co-crystal ligand with respect to the G protein and arrestin mediated signaling. This functional fidelity has important implications in drug design, as the ability to predict ligands with predefined signaling properties is highly desirable. However, the agonist-bound state provides an uncertain template for modeling the activated conformation of other GPCRs, as a dopamine D2 receptor (DRD2) activated model templated on the activated β2AR structure returned few hits of only marginal potency.

  15. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons.

    Directory of Open Access Journals (Sweden)

    Sergiy V Korol

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM, an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM plus diazepam (1 μM, only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons.

  16. Identification and in Vivo Evaluation of Liver X Receptor β-Selective Agonists for the Potential Treatment of Alzheimer’s Disease

    Energy Technology Data Exchange (ETDEWEB)

    Stachel, Shawn J.; Zerbinatti, Celina; Rudd, Michael T.; Cosden, Mali; Suon, Sokreine; Nanda, Kausik K.; Wessner, Keith; DiMuzio, Jillian; Maxwell, Jill; Wu, Zhenhua; Uslaner, Jason M.; Michener, Maria S.; Szczerba, Peter; Brnardic, Edward; Rada, Vanessa; Kim, Yuntae; Meissner, Robert; Wuelfing, Peter; Yuan, Yang; Ballard, Jeanine; Holahan, Marie; Klein, Daniel J.; Lu, Jun; Fradera, Xavier; Parthasarathy, Gopal; Uebele, Victor N.; Chen, Zhongguo; Li, Yingjie; Li, Jian; Cooke, Andrew J.; Bennett, D. Jonathan; Bilodeau, Mark T.; Renger, John (Merck); (WuXi App Tec)

    2016-04-14

    Herein, we describe the development of a functionally selective liver X receptor β (LXRβ) agonist series optimized for Emax selectivity, solubility, and physical properties to allow efficacy and safety studies in vivo. Compound 9 showed central pharmacodynamic effects in rodent models, evidenced by statistically significant increases in apolipoprotein E (apoE) and ATP-binding cassette transporter levels in the brain, along with a greatly improved peripheral lipid safety profile when compared to those of full dual agonists. These findings were replicated by subchronic dosing studies in non-human primates, where cerebrospinal fluid levels of apoE and amyloid-β peptides were increased concomitantly with an improved peripheral lipid profile relative to that of nonselective compounds. These results suggest that optimization of LXR agonists for Emax selectivity may have the potential to circumvent the adverse lipid-related effects of hepatic LXR activity.

  17. Common structural basis for constitutive activity of the ghrelin receptor family

    DEFF Research Database (Denmark)

    Holst, Birgitte; Holliday, Nicholas D; Bach, Anders

    2004-01-01

    Three members of the ghrelin receptor family were characterized in parallel: the ghrelin receptor, the neurotensin receptor 2 and the orphan receptor GPR39. In transiently transfected COS-7 and human embryonic kidney 293 cells, all three receptors displayed a high degree of ligand......-independent signaling activity. The structurally homologous motilin receptor served as a constitutively silent control; upon agonist stimulation, however, it signaled with a similar efficacy to the three related receptors. The constitutive activity of the ghrelin receptor and of neurotensin receptor 2 through the G...... demonstrated that the epitope-tagged ghrelin receptor was constitutively internalized but could be trapped at the cell surface by an inverse agonist, whereas GPR39 remained at the cell surface. Mutational analysis showed that the constitutive activity of both the ghrelin receptor and GPR39 could systematically...

  18. Helix 11 Dynamics is Critical for Constitutive Androstane Receptor Activity

    OpenAIRE

    Wright, Edward; Busby, Scott A.; Wisecarver, Sarah; Vincent, Jeremy; Griffin, Patrick R.; Fernandez, Elias J.

    2011-01-01

    The constitutive androstane receptor (CAR) transactivation can occur in the absence of exogenous ligand and this activity is enhanced by agonists TCPOBOP and meclizine. We use biophysical and cell-based assays to show that increased activity of CAR(TCPOBOP) relative to CAR(meclizine) corresponds to a higher affinity of CAR(TCPOBOP) for the steroid receptor coactivator-1. Additionally, steady-state fluorescence spectra suggest conformational differences between CAR(TCPOBOP):RXR and CAR(meclizi...

  19. Chronic exposure to dopamine agonists affects the integrity of striatal D2 receptors in Parkinson's patients

    Directory of Open Access Journals (Sweden)

    Marios Politis

    2017-01-01

    Full Text Available We aimed to investigate the integrity and clinical relevance of striatal dopamine receptor type-2 (D2R availability in Parkinson's disease (PD patients. We studied 68 PD patients, spanning from early to advanced disease stages, and 12 healthy controls. All participants received one [11C]raclopride PET scan in an OFF medication condition for quantification of striatal D2R availability in vivo. Parametric images of [11C]raclopride non-displaceable binding potential were generated from the dynamic [11C]raclopride scans using implementation of the simplified reference tissue model with cerebellum as the reference tissue. PET data were interrogated for correlations with clinical data related to disease burden and dopaminergic treatment. PD patients showed a mean 16.7% decrease in caudate D2R and a mean 3.5% increase in putaminal D2R availability compared to healthy controls. Lower caudate [11C]raclopride BPND correlated with longer PD duration. PD patients on dopamine agonist treatment had 9.2% reduced D2R availability in the caudate and 12.8% in the putamen compared to PD patients who never received treatment with dopamine agonists. Higher amounts of lifetime dopamine agonist therapy correlated with reduced D2Rs availability in both caudate and putamen. No associations between striatal D2R availability and levodopa treatment and dyskinesias were found. In advancing PD the caudate and putamen D2R availability are differentially affected. Chronic exposure to treatment with dopamine agonists, but no levodopa, suppresses striatal D2R availability, which may have relevance to output signaling to frontal lobes and the occurrence of executive deficits, but not dyskinesias.

  20. Diabetes and obesity treatment based on dual incretin receptor activation

    DEFF Research Database (Denmark)

    Skow, M A; Bergmann, N C; Knop, F K

    2016-01-01

    , whereas GIP seems to affect lipid metabolism. The introduction of selective GLP-1 receptor (GLP-1R) agonists for the treatment of type 2 diabetes and obesity has increased the scientific and clinical interest in incretins. Combining the body weight-lowering and glucose-lowering effects of GLP-1...... with a more potent improvement of β cell function through additional GIP action could potentially offer a more effective treatment of diabetes and obesity, with fewer adverse effects than selective GLP-1R agonists; therefore, new drugs designed to co-activate both the GIP receptor (GIPR) and the GLP-1R...

  1. Molecular interaction of a potent nonpeptide agonist with the chemokine receptor CCR8

    DEFF Research Database (Denmark)

    Jensen, Pia C; Nygaard, Rie; Thiele, Stefanie

    2007-01-01

    Most nonpeptide antagonists for CC-chemokine receptors share a common pharmacophore with a centrally located, positively charged amine that interacts with the highly conserved glutamic acid (Glu) located in position 6 of transmembrane helix VII (VII:06). We present a novel CCR8 nonpeptide agonist......, 8-[3-(2-methoxyphenoxy)benzyl]-1-phenethyl-1,3,8-triaza-spiro[4.5]decan-4-one (LMD-009), that also contains a centrally located, positively charged amine. LMD-009 selectively stimulated CCR8 among the 20 identified human chemokine receptors. It mediated chemotaxis, inositol phosphate accumulation......-binding pockets of CCR8 uncovered that the binding of LMD-009 and of four analogs [2-(1-(3-(2-methoxyphenoxy)benzyl)-4-hydroxypiperidin-4-yl)benzoic acid (LMD-584), N-ethyl-2-4-methoxybenzenesulfonamide (LMD-902), N-(1-(3-(2-methoxyphenoxy)benzyl)piperidin-4-yl)-2-phenyl-4-(pyrrolidin-1yl)butanamide (LMD-268...

  2. Neutral Loss Scan - Based Strategy for Integrated Identification of Amorfrutin Derivatives, New Peroxisome Proliferator-Activated Receptor Gamma Agonists, from Amorpha Fruticosa by UPLC-QqQ-MS/MS and UPLC-Q-TOF-MS.

    Science.gov (United States)

    Chen, Chu; Xue, Ying; Li, Qing-Miao; Wu, Yan; Liang, Jian; Qing, Lin-Sen

    2018-04-01

    Amorfrutins with a 2-hydroxybenzoic acid core structure are promising natural PPARγ agonists with potent antidiabetic activity. Owing to the complex matrix and low concentration in botanical material, the identification of unknown amorfrutins remains a challenge. In the present study, a combined application of UPLC-Q-TOF-MS and UPLC-QqQ-MS was developed to discover unknown amorfrutins from fruits of Amorpha fruticosa. First, reference compounds of amorfrutin A (AA), amorfrutin B (AB), and 2-carboxy-3,5-dihydroxy-4-geranylbibenzyl (AC) were analyzed using UPLC-Q-TOF-MS to reveal the characteristic fragment ions and the possible neutral loss. Second, the extract of A. fruticosa was separated and screened by UPLC-QqQ-MS using neutral loss scan to find out suspect compounds associated with the specified neutral fragment Δm/z 44. Third, the extract was re-analyzed by UPLC-Q-TOF-MS to obtain the exact mass of quasi-molecular ion and fragment ions of each suspect compound, and to subsequently calculate their corresponding molecular formulas. Finally, according to the molecular formula of suspect compound and its fragment ions and comparing with literature data, structure elucidation of four unidentified amorfrutins was achieved. The results indicated that the combination of QqQ-MS neutral loss scan and Q-TOF-MS molecular formula calculation was proven to be a powerful tool for unknown natural product identification, and this strategy provides an effective solution to discover natural products or metabolites of trace content. Graphical Abstract ᅟ.

  3. Recent Advances in GLP-1 Receptor Agonists for Use in Diabetes Mellitus.

    Science.gov (United States)

    McBrayer, Dominic N; Tal-Gan, Yftah

    2017-09-01

    Preclinical Research Mimetics of Glucagon-like peptide 1 (GLP-1) represent a useful alternative or complementary treatment choice to insulin in the treatment of diabetes mellitus. The lack of hypoglycemia as a side effect when GLP-1 receptor agonists are used along with the tendency of these therapeutic agents to prevent or even reduce weight gain makes them valuable targets in therapy development. However, native GLP-1 and many of its early analogues have very short half-lives, requiring repeated treatment to maintain therapeutic levels. As all current treatments are injected subcutaneously, a large focus has been made on trying to extend the half-lives of GLP-1 analogues while retaining bioactivity. Most success in this regard has been achieved with the use of peptide-protein fusions, which are not as well suited for oral administration. However, recent work focused on the development of non-fusion peptides with increased half-lives that may be more appropriate for oral administration. This minireview discusses the structural characteristics of past and present analogues as well as the recent work conducted toward developing novel GLP-1 receptor agonists. Drug Dev Res 78 : 292-299, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. Novel retinoic acid receptor alpha agonists for treatment of kidney disease.

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    Yifei Zhong

    Full Text Available Development of pharmacologic agents that protect podocytes from injury is a critical strategy for the treatment of kidney glomerular diseases. Retinoic acid reduces proteinuria and glomerulosclerosis in multiple animal models of kidney diseases. However, clinical studies are limited because of significant side effects of retinoic acid. Animal studies suggest that all trans retinoic acid (ATRA attenuates proteinuria by protecting podocytes from injury. The physiological actions of ATRA are mediated by binding to all three isoforms of the nuclear retinoic acid receptors (RARs: RARα, RARβ, and RARγ. We have previously shown that ATRA exerts its renal protective effects mainly through the agonism of RARα. Here, we designed and synthesized a novel boron-containing derivative of the RARα-specific agonist Am580. This new derivative, BD4, binds to RARα receptor specifically and is predicted to have less toxicity based on its structure. We confirmed experimentally that BD4 binds to RARα with a higher affinity and exhibits less cellular toxicity than Am580 and ATRA. BD4 induces the expression of podocyte differentiation markers (synaptopodin, nephrin, and WT-1 in cultured podocytes. Finally, we confirmed that BD4 reduces proteinuria and improves kidney injury in HIV-1 transgenic mice, a model for HIV-associated nephropathy (HIVAN. Mice treated with BD4 did not develop any obvious toxicity or side effect. Our data suggest that BD4 is a novel RARα agonist, which could be used as a potential therapy for patients with kidney disease such as HIVAN.

  5. GLP-1 receptor agonists in the treatment of polycystic ovary syndrome.

    Science.gov (United States)

    Lamos, Elizabeth Mary; Malek, Rana; Davis, Stephen N

    2017-04-01

    Polycystic ovarian syndrome (PCOS) affects many women of child-bearing age and is characterized by hyperandrogenism, ovulatory and metabolic dysfunction. A primary treatment goal is weight reduction. The weight loss effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), previously demonstrated in diabetic and obese non-diabetic patients, offer a unique opportunity to expand the medical options available to PCOS patients. Areas covered: Available clinical trials of glucagon-like peptide-1 receptor agonist therapy in PCOS were reviewed. Literature was searched from PubMed using appropriate search terms up to November 2016. Expert commentary: The available studies of GLP-1 RA therapy in the treatment of excess body weight in women with PCOS demonstrate that exenatide and liraglutide are effective in weight reduction either as monotherapy or in combination with metformin. A few studies showed that androgens may be modestly decreased and menstrual frequency may be increased. Eating behavior may be improved with liraglutide therapy. Glucose parameters are generally improved. GLP-1RAs were well-tolerated, with nausea being the most significant adverse side effect. Barriers to utilization may be the short duration studies, lack of familiarity of the medication, the route of administration (injection) and the variable outcomes on ovulation and hyperandrogenism.

  6. Maternal aggression in Wistar rats: effect of 5-HT2A/2C receptor agonist and antagonist microinjected into the dorsal periaqueductal gray matter and medial septum

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    Almeida R.M.M. de

    2005-01-01

    Full Text Available The objective of the present study was to assess the role of the 5-HT2A/2C receptor at two specific brain sites, i.e., the dorsal periaqueductal gray matter (DPAG and the medial septal (MS area, in maternal aggressive behavior after the microinjection of either a 5-HT2A/2C receptor agonist or antagonist. Female Wistar rats were microinjected on the 7th postpartum day with the selective agonist alpha-methyl-5-hydroxytryptamine maleate (5-HT2A/2C or the antagonist 5-HT2A/2C, ketanserin. The agonist was injected into the DPAG at 0.2 (N = 9, 0.5 (N = 10, and 1.0 µg/0.2 µl (N = 9, and the antagonist was injected at 1.0 µg/0.2 µl (N = 9. The agonist was injected into the medial septal area (MS at 0.2 (N = 9, 0.5 (N = 7, and 1.0 µg/0.2 µl (N = 6 and the antagonist was injected at 1.0 µg/0.2 µl (N = 5. For the control, saline was injected into the DPAG (N = 7 and the MS (N = 12. Both areas are related to aggressive behavior and contain a high density of 5-HT receptors. Non-aggressive behaviors such as horizontal locomotion (walking and social investigation and aggressive behaviors such as lateral threat (aggressive posture, attacks (frontal and lateral, and biting the intruder were analyzed when a male intruder was placed into the female resident's cage. For each brain area studied, the frequency of the behaviors was compared among the various treatments by analysis of variance. The results showed a decrease in maternal aggressive behavior (number of bites directed at the intruder after microinjection of the agonist at 0.2 and 1.0 µg/0.2 µl (1.6 ± 0.7 and 0.9 ± 0.3 into the DPAG compared to the saline group (5.5 ± 1.1. There was no dose-response relationship with the agonist. The present findings suggest that the 5-HT2A/2C receptor agonist has an inhibitory effect on maternal aggressive behavior when microinjected into the DPAG and no effect when microinjected into the MS. Ketanserin (1.0 µg/0.2 µl decreased locomotion when microinjected

  7. Discovery and Characterization of a Novel Small-Molecule Agonist for Medium-Chain Free Fatty Acid Receptor G Protein-Coupled Receptor 84.

    Science.gov (United States)

    Zhang, Qing; Yang, Hui; Li, Jing; Xie, Xin

    2016-05-01

    G protein-coupled receptor 84 (GPR84) is a free fatty acid receptor activated by medium-chain free fatty acids with 9-14 carbons. It is expressed mainly in the immune-related tissues, such as spleen, bone marrow, and peripheral blood leukocytes. GPR84 plays significant roles in inflammatory processes and may represent a novel drug target for the treatment of immune-mediated diseases. However, the lack of potent and specific ligands for GPR84 hindered the study of its functions and the development of potential clinical applications. Here, we report the screen of 160,000 small-molecule compounds with a calcium mobilization assay using a human embryonic kidney 293 cell line stably expressing GPR84 and Gα16, and the identification of 2-(hexylthio)pyrimidine-4,6-diol (ZQ-16) as a potent and selective agonist of GPR84 with a novel structure. ZQ-16 activates several GPR84-mediated signaling pathways, including calcium mobilization, inhibition of cAMP accumulation, phosphorylation of extracellular signal-regulated protein kinase 1/2, receptor desensitization and internalization, and receptor-β-arrestin interaction. This compound may be a useful tool to study the functions of GPR84 and a potential candidate for further structural optimization. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  8. Neonatal co-lesion by DSP-4 and 5,7-DHT produces adulthood behavioral sensitization to dopamine D(2) receptor agonists.

    Science.gov (United States)

    Nowak, Przemysław; Nitka, Dariusz; Kwieciński, Adam; Jośko, Jadwiga; Drab, Jacek; Pojda-Wilczek, Dorota; Kasperski, Jacek; Kostrzewa, Richard M; Brus, Ryszard

    2009-01-01

    To assess the possible modulatory effects of noradrenergic and serotoninergic neurons on dopaminergic neuronal activity, the noradrenergic and serotoninergic neurotoxins DSP-4 N-(2-chlorethyl)-N-ethyl-2-bromobenzylamine (50.0 mg/kg, sc) and 5,7-dihydroxytryptamine (5,7-DHT) (37.5 microg icv, half in each lateral ventricle), respectively, were administered toWistar rats on the first and third days of postnatal ontogeny, and dopamine (DA) agonist-induced behaviors were assessed in adulthood. At eight weeks, using an HPLC/ED technique, DSP-4 treatment was associated with a reduction in NE content of the corpus striatum (> 60%), hippocampus (95%), and frontal cortex (> 85%), while 5,7-DHT was associated with an 80-90% serotonin reduction in the same brain regions. DA content was unaltered in the striatum and the cortex. In the group lesioned with both DSP-4 and 5,7-DHT, quinpirole-induced (DA D(2) agonist) yawning, 7-hydroxy-DPAT-induced (DA D(3) agonist) yawning, and apomorphine-induced (non-selective DA agonist) stereotypies were enhanced. However, SKF 38393-induced (DA D(1) agonist) oral activity was reduced in the DSP-4 + 5,7-DHT group. These findings demonstrate that DA D(2)- and D(3)-agonist-induced behaviors are enhanced while DA D(1)-agonist-induced behaviors are suppressed in adult rats in which brain noradrenergic and serotoninergic innervation of the brain has largely been destroyed. This study indicates that noradrenergic and serotoninergic neurons have a great impact on the development of DA receptor reactivity (sensitivity).

  9. A flagellin-derived toll-like receptor 5 agonist stimulates cytotoxic lymphocyte-mediated tumor immunity.

    Directory of Open Access Journals (Sweden)

    Nicholas D Leigh

    Full Text Available Toll-like receptor (TLR mediated recognition of pathogen associated molecular patterns allows the immune system to rapidly respond to a pathogenic insult. The "danger context" elicited by TLR agonists allows an initially non-immunogenic antigen to become immunogenic. This ability to alter environment is highly relevant in tumor immunity, since it is inherently difficult for the immune system to recognize host-derived tumors as immunogenic. However, immune cells may have encountered certain TLR ligands associated with tumor development, yet the endogenous stimulation is typically not sufficient to induce spontaneous tumor rejection. Of special interest are TLR5 agonists, because there are no endogenous ligands that bind TLR5. CBLB502 is a pharmacologically optimized TLR5 agonist derived from Salmonella enterica flagellin. We examined the effect of CBLB502 on tumor immunity using two syngeneic lymphoma models, both of which do not express TLR5, and thus do not directly respond to CBLB502. Upon challenge with the T-cell lymphoma RMAS, CBLB502 treatment after tumor inoculation protects C57BL/6 mice from death caused by tumor growth. This protective effect is both natural killer (NK cell- and perforin-dependent. In addition, CBLB502 stimulates clearance of the B-cell lymphoma A20 in BALB/c mice in a CD8(+ T cell-dependent fashion. Analysis on the cellular level via ImageStream flow cytometry reveals that CD11b(+ and CD11c(+ cells, but neither NK nor T cells, directly respond to CBLB502 as determined by NFκB nuclear translocation. Our findings demonstrate that CBLB502 stimulates a robust antitumor response by directly activating TLR5-expressing accessory immune cells, which in turn activate cytotoxic lymphocytes.

  10. 5-HT2 and 5-HT7 receptor agonists facilitate plantar stepping in chronic spinal rats through actions on different populations of spinal neurons

    Directory of Open Access Journals (Sweden)

    Urszula eSlawinska

    2014-08-01

    Full Text Available There is considerable evidence from research in neonatal and adult rat and mouse preparations to warrant the conclusion that activation of 5-HT2 and 5-HT1A/7 receptors leads to activation of the spinal cord circuitry for locomotion. These receptors are involved in control of locomotor movements, but it is not clear how they are implicated in the responses to 5-HT agonists observed after spinal cord injury. Here we used agonists that are efficient in promoting locomotor recovery in paraplegic rats, 8-OHDPAT (acting on 5-HT1A/7 receptors and quipazine (acting on 5-HT2 receptors, to examine this issue. Analysis of intra- and interlimb coordination confirmed that the locomotor performance was significantly improved by either drug, but the data revealed marked differences in their mode of action. Interlimb coordination was significantly better after 8-OHDPAT application, and the activity of the extensor soleus muscle was significantly longer during the stance phase of locomotor movements enhanced by quipazine. Our results show that activation of both receptors facilitates locomotion, but their effects are likely exerted on different populations of spinal neurons. Activation of 5-HT2 receptors facilitates the output stage of the locomotor system, in part by directly activating motoneurons, and also through activation of interneurons of the locomotor CPG. Activation of 5-HT7/1A receptors facilitates the activity of the locomotor CPG, without direct actions on the output components of the locomotor system, including motoneurons. Although our findings show that the combined use of these two drugs results in production of well-coordinated weight supported locomotion with a reduced need for exteroceptive stimulation, they also indicate that there might be some limitations to the utility of combined treatment. Sensory feedback and some intraspinal circuitry recruited by the drugs can conflict with the locomotor activation.

  11. 5-HT₂ and 5-HT₇ receptor agonists facilitate plantar stepping in chronic spinal rats through actions on different populations of spinal neurons.

    Science.gov (United States)

    Sławińska, Urszula; Miazga, Krzysztof; Jordan, Larry M

    2014-01-01

    There is considerable evidence from research in neonatal and adult rat and mouse preparations to warrant the conclusion that activation of 5-HT2 and 5-HT1A/7 receptors leads to activation of the spinal cord circuitry for locomotion. These receptors are involved in control of locomotor movements, but it is not clear how they are implicated in the responses to 5-HT agonists observed after spinal cord injury. Here we used agonists that are efficient in promoting locomotor recovery in paraplegic rats, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OHDPAT) (acting on 5-HT1A/7 receptors) and quipazine (acting on 5-HT2 receptors), to examine this issue. Analysis of intra- and interlimb coordination confirmed that the locomotor performance was significantly improved by either drug, but the data revealed marked differences in their mode of action. Interlimb coordination was significantly better after 8-OHDPAT application, and the activity of the extensor soleus muscle was significantly longer during the stance phase of locomotor movements enhanced by quipazine. Our results show that activation of both receptors facilitates locomotion, but their effects are likely exerted on different populations of spinal neurons. Activation of 5-HT2 receptors facilitates the output stage of the locomotor system, in part by directly activating motoneurons, and also through activation of interneurons of the locomotor central pattern generator (CPG). Activation of 5-HT7/1A receptors facilitates the activity of the locomotor CPG, without direct actions on the output components of the locomotor system, including motoneurons. Although our findings show that the combined use of these two drugs results in production of well-coordinated weight supported locomotion with a reduced need for exteroceptive stimulation, they also indicate that there might be some limitations to the utility of combined treatment. Sensory feedback and some intraspinal circuitry recruited by the drugs can conflict with the

  12. Aryl hydrocarbon receptor (AhR agonists suppress interleukin-6 expression by bone marrow stromal cells: an immunotoxicology study

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    Schlezinger Jennifer J

    2003-12-01

    Full Text Available Abstract Background Bone marrow stromal cells produce cytokines required for the normal growth and development of all eight hematopoietic cell lineages. Aberrant cytokine production by stromal cells contributes to blood cell dyscrasias. Consequently, factors that alter stromal cell cytokine production may significantly compromise the development of normal blood cells. We have shown that environmental chemicals, such as aromatic hydrocarbon receptor (AhR agonists, suppress B lymphopoiesis by modulating bone marrow stromal cell function. Here, we extend these studies to evaluate the potential for two prototypic AhR agonists, 7,12-dimethylbenz [a]anthracene (DMBA and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, to alter stromal cell cytokine responses. Methods Bone marrow stromal cells were treated with AhR agonists and bacterial lipopolysaccharide (LPS to mimic innate inflammatory cytokine responses and to study the effects of AhR ligands on those responses. Steady state cytokine RNA levels were screened by RNAse protection assays (RPA and quantified by real-time PCR. Cytokine (IL-6 protein production was measured by ELISA. NF-κB EMSAs were used to study IL-6 transcriptional regulation. Results RPAs indicated that AhR+ bone marrow stromal cells consistently up-regulated genes encoding IL-6 and LIF in response to LPS, presumably through activation of Toll-like receptor 4. Pre-treatment with low doses of DMBA or TCDD selectively abrogated IL-6 gene induction but had no effect on LIF mRNA. Real-time-PCR indicated a significant inhibition of IL-6 mRNA by AhR ligands within 1 hour of LPS challenge which was reflected in a profound down-regulation of IL-6 protein induction, with DMBA and TCDD suppressing IL-6 levels as much as 65% and 88%, respectively. This potent inhibitory effect persisted for at least 72 hours. EMSAs measuring NF-κB binding to IL-6 promoter sequences, an event known to induce IL-6 transcription, indicated a significant decrease in

  13. Antipsychotic-like effect of the muscarinic acetylcholine receptor agonist BuTAC in non-human primates

    DEFF Research Database (Denmark)

    Andersen, Maibritt B; Croy, Carrie Hughes; Dencker, Ditte

    2015-01-01

    Cholinergic, muscarinic receptor agonists exhibit functional dopamine antagonism and muscarinic receptors have been suggested as possible future targets for the treatment of schizophrenia and drug abuse. The muscarinic ligand (5R,6R)-6-(3-butylthio-1,2,5-thiadiazol-4-yl)-1-azabicyclo[3.2.1]octane...... (BuTAC) exhibits high affinity for muscarinic receptors with no or substantially less affinity for a large number of other receptors and binding sites, including the dopamine receptors and the dopamine transporter. In the present study, we wanted to examine the possible antipsychotic-like effects...

  14. Aryl hydrocarbon receptor (AhR and its endogenous agonist – indoxyl sulfate in chronic kidney disease

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    Tomasz Kamiński

    2017-07-01

    Full Text Available The indoxyl sulfate (IS, indoxyl sulphate is the end product of dietary tryptophan degradation by indole pathway and significantly higher serum and tissue concentrations of this compound is observed in patients with impaired renal function. Despite the high albumin binding affinity, the remaining free fraction of IS has a number of biological effects related to the generation of oxidative stress andactivation of signaling pathways related to NF-кB, p53 protein, STAT3, TGF-β and Smad2/3. IS induces the inflammatory process, exerts nephrotoxic activity and is also a factor impairing the cardiovascular system.Its high concentrations are associated with the occurrence of cardiovascular incidents, whose frequency is significantly higher in patients with chronic kidney disease. Evaluation of the mechanisms that underlie the high reactivity of indoxyl sulfate and its biological effects showed that this compound is an agonist of the aryl hydrocarbon receptor (AhR. This receptor plays an important role in maintaining homeostasis Moreover, AhR exerts high transcriptional activity, so ligands of obciążethis receptor may exert different biological effects. The following paper describes the role of indoxyl sulfate as AhR ligand in the context of the excessive accumulation, which appears as one of the symptoms associated with chronic kidney disease.

  15. Polyamidoamine (PAMAM) Dendrimer Conjugates of Clickable Agonists of the A3 Adenosine Receptor and Coactivation of the P2Y14 Receptor by a Tethered Nucleotide

    Energy Technology Data Exchange (ETDEWEB)

    Tosh, Dilip, K. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Yoo, Lena S. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Chinn, Moshe [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Hong, Kunlun [ORNL; Kilbey, II, S Michael [ORNL; Barrett, Matthew O. [University of North Carolina School of Medicine; Fricks, Ingrid P. [University of North Carolina School of Medicine; Harden, T. Kendall [University of North Carolina School of Medicine; Jacobson, Kenneth A. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health

    2010-01-01

    We previously synthesized a series of potent and selective A{sub 3} adenosine receptor (AR) agonists (North-methanocarba nucleoside 5{prime}-uronamides) containing dialkyne groups on extended adenine C2 substituents. We coupled the distal alkyne of a 2-octadiynyl nucleoside by Cu(I)-catalyzed 'click' chemistry to azide-derivatized G4 (fourth-generation) PAMAM dendrimers to form triazoles. A{sub 3}AR activation was preserved in these multivalent conjugates, which bound with apparent Ki of 0.1-0.3 nM. They were substituted with nucleoside moieties, solely or in combination with water-solubilizing carboxylic acid groups derived from hexynoic acid. A comparison with various amide-linked dendrimers showed that triazole-linked conjugates displayed selectivity and enhanced A{sub 3}AR affinity. We prepared a PAMAM dendrimer containing equiproportioned peripheral azido and amino groups for conjugation of multiple ligands. A bifunctional conjugate activated both A{sub 3} and P2Y{sub 14} receptors (via amide-linked uridine-5{prime}-diphosphoglucuronic acid), with selectivity in comparison to other ARs and P2Y receptors. This is the first example of targeting two different GPCRs with the same dendrimer conjugate, which is intended for activation of heteromeric GPCR aggregates. Synergistic effects of activating multiple GPCRs with a single dendrimer conjugate might be useful in disease treatment.

  16. Receptor structure-based discovery of non-metabolite agonists for the succinate receptor GPR91

    DEFF Research Database (Denmark)

    Trauelsen, Mette; Rexen Ulven, Elisabeth; Hjorth, Siv A

    2017-01-01

    therefore binds in a very different mode than generally believed. Importantly, an empty side-pocket is identified next to the succinate binding site. All this information formed the basis for a substructure-based search query, which, combined with molecular docking, was used in virtual screening of the ZINC...... database to pick two serial mini-libraries of a total of only 245 compounds from which sub-micromolar, selective GPR91 agonists of unique structures were identified. The best compounds were backbone-modified succinate analogs in which an amide-linked hydrophobic moiety docked into the side-pocket next...

  17. Sphingosine-1-Phosphate Receptor-1 Selective Agonist Enhances Collateral Growth and Protects against Subsequent Stroke.

    Directory of Open Access Journals (Sweden)

    Masahiko Ichijo

    Full Text Available Collateral growth after acute occlusion of an intracranial artery is triggered by increasing shear stress in preexisting collateral pathways. Recently, sphingosine-1-phosphate receptor-1 (S1PR1 on endothelial cells was reported to be essential in sensing fluid shear stress. Here, we evaluated the expression of S1PR1 in the hypoperfused mouse brain and investigated the effect of a selective S1PR1 agonist on leptomeningeal collateral growth and subsequent ischemic damage after focal ischemia.In C57Bl/6 mice (n = 133 subjected to unilateral common carotid occlusion (CCAO and sham surgery. The first series examined the time course of collateral growth, cell proliferation, and S1PR1 expression in the leptomeningeal arteries after CCAO. The second series examined the relationship between pharmacological regulation of S1PR1 and collateral growth of leptomeningeal anastomoses. Animals were randomly assigned to one of the following groups: LtCCAO and daily intraperitoneal (i.p. injection for 7 days of an S1PR1 selective agonist (SEW2871, 5 mg/kg/day; sham surgery and daily i.p. injection for 7 days of SEW2871 after surgery; LtCCAO and daily i.p. injection for 7 days of SEW2871 and an S1PR1 inverse agonist (VPC23019, 0.5 mg/kg; LtCCAO and daily i.p. injection of DMSO for 7 days after surgery; and sham surgery and daily i.p. injection of DMSO for 7 days. Leptomeningeal anastomoses were visualized 14 days after LtCCAO by latex perfusion method, and a set of animals underwent subsequent permanent middle cerebral artery occlusion (pMCAO 7 days after the treatment termination. Neurological functions 1 hour, 1, 4, and 7 days and infarction volume 7 days after pMCAO were evaluated.In parallel with the increase in S1PR1 mRNA levels, S1PR1 expression colocalized with endothelial cell markers in the leptomeningeal arteries, increased markedly on the side of the CCAO, and peaked 7 days after CCAO. Mitotic cell numbers in the leptomeningeal arteries increased after

  18. Characterization of a series of anabaseine-derived compounds reveals that the 3-(4)-dimethylaminocinnamylidine derivative is a selective agonist at neuronal nicotinic alpha 7/125I-alpha-bungarotoxin receptor subtypes.

    Science.gov (United States)

    de Fiebre, C M; Meyer, E M; Henry, J C; Muraskin, S I; Kem, W R; Papke, R L

    1995-01-01

    Investigation of the naturally occurring, nicotinic agonist anabaseine and novel derivatives has shown that these compounds have cytoprotective and memory-enhancing effects. The hypothesis that these arise at least in part through actions on brain nicotinic receptors was evaluated by examining the ability of these compounds to displace the binding of nicotinic ligands and to affect the function of the alpha 4 beta 2 and alpha 7 receptor subtypes expressed in Xenopus oocytes. The derivative 3-(4)-dimethylaminocinnamylidine anabaseine (DMAC) was found to be a selective alpha 7 receptor agonist; it was more potent than nicotine, acetylcholine, anabaseine, and other derivatives at activating the alpha 7 receptor subtype, while displaying little agonist activity at alpha 4 beta 2 and other receptor subtypes. Compared with anabaseine and the other derivatives, DMAC was the most potent at displacing 125I-alpha-bungarotoxin binding (putative alpha 7) and the least potent at displacing [3H]cytisine binding (putative alpha 4 beta 2) to brain membranes. Independently of agonist activities, all of the novel compounds displayed secondary inhibitory activity at both receptor subtypes. At the alpha 4 beta 2 receptor subtype, inhibition by the 3-(2,4)-dimethoxybenzylidene derivative was enhanced by coapplication of acetylcholine, suggesting a noncompetitive form of inhibition. Anabaseine and nicotine prolonged the time course of activation of alpha 4 beta 2 receptors, compared with acetylcholine, suggesting sequential channel-blocking activity. As selective agonists, anabaseine derivatives such as DMAC may be useful for elucidating the function of alpha 7 nicotinic receptors, including their potential role(s) in the cytoprotective and memory-enhancing effects of nicotinic agents.

  19. Reduced beta-adrenergic receptor activation decreases G-protein expression and beta-adrenergic receptor kinase activity in porcine heart.

    OpenAIRE

    Ping, P; Gelzer-Bell, R; Roth, D A; Kiel, D; Insel, P A; Hammond, H K

    1995-01-01

    To determine whether beta-adrenergic receptor agonist activation influences guanosine 5'-triphosphate-binding protein (G-protein) expression and beta-adrenergic receptor kinase activity in the heart, we examined the effects of chronic beta 1-adrenergic receptor antagonist treatment (bisoprolol, 0.2 mg/kg per d i.v., 35 d) on components of the myocardial beta-adrenergic receptor-G-protein-adenylyl cyclase pathway in porcine myocardium. Three novel alterations in cardiac adrenergic signaling as...

  20. Growth hormone-releasing hormone as an agonist of the ghrelin receptor GHS-R1a.

    Science.gov (United States)

    Casanueva, Felipe F; Camiña, Jesus P; Carreira, Marcos C; Pazos, Yolanda; Varga, Jozsef L; Schally, Andrew V

    2008-12-23

    Ghrelin synergizes with growth hormone-releasing hormone (GHRH) to potentiate growth hormone (GH) response through a mechanism not yet fully characterized. This study was conducted to analyze the role of GHRH as a potential ligand of the ghrelin receptor, GHS-R1a. The results show that hGHRH(1-29)NH(2) (GHRH) induces a dose-dependent calcium mobilization in HEK 293 cells stably transfected with GHS-R1a an effect not observed in wild-type HEK 293 cells. This calcium rise is also observed using the GHRH receptor agonists JI-34 and JI-36. Radioligand binding and cross-linking studies revealed that calcium response to GHRH is mediated by the ghrelin receptor GHS-R1a. GHRH activates the signaling route of inositol phosphate and potentiates the maximal response to ghrelin measured in inositol phosphate turnover. The presence of GHRH increases the binding capacity of (125)I-ghrelin in a dose dependent-fashion showing a positive binding cooperativity. In addition, confocal microscopy in CHO cells transfected with GHS-R1a tagged with enhanced green fluorescent protein shows that GHRH activates the GHS-R1a endocytosis. Furthermore, the selective GHRH-R antagonists, JV-1-42 and JMR-132, act also as antagonists of the ghrelin receptor GHS-R1a. Our findings suggest that GHRH interacts with ghrelin receptor GHS-R1a, and, in consequence, modifies the ghrelin-associated intracellular signaling pathway. This interaction may represent a form of regulation, which could play a putative role in the physiology of GH regulation and appetite control.

  1. Positive versus negative modulation of different endogenous chemokines for CC-chemokine receptor 1 by small molecule agonists through allosteric versus orthosteric binding

    DEFF Research Database (Denmark)

    Jensen, Pia C; Thiele, Stefanie; Ulven, Trond

    2008-01-01

    7 transmembrane-spanning (7TM) chemokine receptors having multiple endogenous ligands offer special opportunities to understand the molecular basis for allosteric mechanisms. Thus, CC-chemokine receptor 1 (CCR1) binds CC-chemokine 3 and 5 (CCL3 and CCL5) with K(d) values of 7.3 and 0.16 nm......5 and not CCL3 activation is affected by substitutions in the main ligand binding pocket including the conserved GluVII:06 anchor point. A series of metal ion chelator complexes were found to act as full agonists on CCR1 and to be critically affected by the same substitutions in the main ligand...... binding pocket as CCL5 but not by mutations in the extracellular domain. In agreement with the overlapping binding sites, the small non-peptide agonists displaced radiolabeled CCL5 with high affinity. Interestingly, the same compounds acted as allosteric enhancers of the binding of CCL3, with which...

  2. Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Hiromasa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Nomiyama, Takashi, E-mail: tnomiyama@fukuoka-u.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Kawamori, Ryuzo [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Beta Cell Biology and Regeneration, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Fujitani, Yoshio; Hirose, Takahisa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Watada, Hirotaka, E-mail: hwatada@juntendo.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan)

    2011-02-04

    Research highlights: {yields} Exendin-4 reduces neointimal formation after vascular injury in a mouse model. {yields} Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. {yields} Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. {yields} Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

  3. Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

    International Nuclear Information System (INIS)

    Goto, Hiromasa; Nomiyama, Takashi; Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio; Kawamori, Ryuzo; Fujitani, Yoshio; Hirose, Takahisa; Watada, Hirotaka

    2011-01-01

    Research highlights: → Exendin-4 reduces neointimal formation after vascular injury in a mouse model. → Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. → Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. → Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

  4. Distinct neural pathways mediate alpha7 nicotinic acetylcholine receptor-dependent activation of the forebrain

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hay-Schmidt, Anders; Hansen, Henrik H

    2010-01-01

    alpha(7) nicotinic acetylcholine receptor (nAChR) agonists are candidates for the treatment of cognitive deficits in schizophrenia. Selective alpha(7) nAChR agonists, such as SSR180711, activate neurons in the medial prefrontal cortex (mPFC) and nucleus accumbens shell (ACCshell) in rats, regions...

  5. The pharmacological rationale for combining muscarinic receptor antagonists and beta-adrenoceptor agonists in the treatment of airway and bladder disease

    NARCIS (Netherlands)

    Dale, Philippa R.; Cernecka, Hana; Schmidt, Martina; Dowling, Mark R.; Charlton, Steven J.; Pieper, Michael P.; Michel, Martin C.

    Muscarinic receptor antagonists and beta-adrenoceptor agonists are used in the treatment of obstructive airway disease and overactive bladder syndrome. Here we review the pharmacological rationale for their combination. Muscarinic receptors and beta-adrenoceptors are physiological antagonists for

  6. Structure-Activity Relationships Based on 3D-QSAR CoMFA/CoMSIA and Design of Aryloxypropanol-Amine Agonists with Selectivity for the Human β3-Adrenergic Receptor and Anti-Obesity and Anti-Diabetic Profiles

    Directory of Open Access Journals (Sweden)

    Marcos Lorca

    2018-05-01

    Full Text Available The wide tissue distribution of the adrenergic β3 receptor makes it a potential target for the treatment of multiple pathologies such as diabetes, obesity, depression, overactive bladder (OAB, and cancer. Currently, there is only one drug on the market, mirabegron, approved for the treatment of OAB. In the present study, we have carried out an extensive structure-activity relationship analysis of a series of 41 aryloxypropanolamine compounds based on three-dimensional quantitative structure-activity relationship (3D-QSAR techniques. This is the first combined comparative molecular field analysis (CoMFA and comparative molecular similarity index analysis (CoMSIA study in a series of selective aryloxypropanolamines displaying anti-diabetes and anti-obesity pharmacological profiles. The best CoMFA and CoMSIA models presented values of r2ncv = 0.993 and 0.984 and values of r2test = 0.865 and 0.918, respectively. The results obtained were subjected to extensive external validation (q2, r2, r2m, etc. and a final series of compounds was designed and their biological activity was predicted (best pEC50 = 8.561.

  7. Synthesis and SAR studies of benzyl ether derivatives as potent orally active S1P₁ agonists.

    Science.gov (United States)

    Tsuji, Takashi; Suzuki, Keisuke; Nakamura, Tsuyoshi; Goto, Taiji; Sekiguchi, Yukiko; Ikeda, Takuya; Fukuda, Takeshi; Takemoto, Toshiyasu; Mizuno, Yumiko; Kimura, Takako; Kawase, Yumi; Nara, Futoshi; Kagari, Takashi; Shimozato, Takaichi; Yahara, Chizuko; Inaba, Shinichi; Honda, Tomohiro; Izumi, Takashi; Tamura, Masakazu; Nishi, Takahide

    2014-08-01

    We report herein the synthesis and structure-activity relationships (SAR) of a series of benzyl ether compounds as an S1P₁ receptor modulator. From our SAR studies, the installation of substituents onto the central benzene ring of 2a was revealed to potently influence the S1P₁ and S1P₃ agonistic activities, in particular, an ethyl group on the 2-position afforded satisfactory S1P₁/S1P₃ selectivity. These changes of the S1P₁ and S1P₃ agonistic activities caused by the alteration of substituents on the 2-position were reasonably explained by a docking study using an S1P₁ X-ray crystal structure and S1P₃ homology modeling. We found that compounds 2b and 2e had a potent in vivo immunosuppressive efficacy along with acceptable S1P₁/S1P₃ selectivity, and confirmed that these compounds had less in vivo bradycardia risk through the evaluation of heart rate change after oral administration of the compounds (30 mg/kg, p.o.) in rats. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Synthesis and in vivo evaluation of [11C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors

    International Nuclear Information System (INIS)

    Dumont, Filip; Waterhouse, Rikki N.; Montoya, Julie A.; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S.; Laruelle, Marc

    2003-01-01

    The synthesis and evaluation of [ 11 C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [ 11 C] methyl iodide afforded the title compound [ 11 C]zolpidem in a yield of 19.19 ± 3.23% in 41 ± 2 min in specific activities of 0.995-1.19 Ci/μmol (1.115 ± 0.105 Ci/μmol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 ± 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [ 11 C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors

  9. Synthesis and in vivo evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Filip; Waterhouse, Rikki N. E-mail: rnw7@columbia.edu; Montoya, Julie A.; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S.; Laruelle, Marc

    2003-05-01

    The synthesis and evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [{sup 11}C] methyl iodide afforded the title compound [{sup 11}C]zolpidem in a yield of 19.19 {+-} 3.23% in 41 {+-} 2 min in specific activities of 0.995-1.19 Ci/{mu}mol (1.115 {+-} 0.105 Ci/{mu}mol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 {+-} 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [{sup 11}C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors.

  10. Synthesis and in vivo evaluation of [11C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors.

    Science.gov (United States)

    Dumont, Filip; Waterhouse, Rikki N; Montoya, Julie A; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S; Laruelle, Marc

    2003-05-01

    The synthesis and evaluation of [(11)C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [(11)C] methyl iodide afforded the title compound [(11)C]zolpidem in a yield of 19.19 +/- 3.23% in 41 +/- 2 min in specific activities of 0.995-1.19 Ci/micromol (1.115 +/- 0.105 Ci/micromol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 +/- 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [(11)C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors.

  11. Role of estrogen receptor β selective agonist in ameliorating portal hypertension in rats with CCl4-induced liver cirrhosis.

    Science.gov (United States)

    Zhang, Cheng-Gang; Zhang, Bin; Deng, Wen-Sheng; Duan, Ming; Chen, Wei; Wu, Zhi-Yong

    2016-05-14

    To investigate the role of diarylpropionitrile (DPN), a selective agonist of estrogen receptor β (ERβ), in liver cirrhosis with portal hypertension (PHT) and isolated hepatic stellate cells (HSCs). Female Sprague-Dawley rats were ovariectomized (OVX), and liver cirrhosis with PHT was induced by CCl4 injection. DPN and PHTPP, the selective ERβ agonist and antagonist, were used as drug interventions. Liver fibrosis was assessed by hematoxylin and eosin (HE) and Masson's trichrome staining and by analyzing smooth muscle actin expression. Hemodynamic parameters were determined in vivo using colored microspheres technique. Protein expression and phosphorylation were determined by immunohistochemical staining and Western blot analysis. Messenger RNA levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Collagen gel contraction assay was performed using gel lattices containing HSCs treated with DPN, PHTPP, or Y-27632 prior to ET-1 addition. Treatment with DPN in vivo greatly lowered portal pressure and improved hemodynamic parameters without affecting mean arterial pressure, which was associated with the attenuation of liver fibrosis and intrahepatic vascular resistance (IHVR). In CCl4-treated rat livers, DPN significantly decreased the expression of RhoA and ROCK II, and even suppressed ROCK II activity. Moreover, DPN remarkedly increased the levels of endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS, and promoted the activities of protein kinase G (PKG), which is an NO effector in the liver. Furthermore, DPN reduced the contractility of activated HSCs in the 3-dimensional stress-relaxed collagen lattices, and decreased the ROCK II activity in activated HSCs. Finally, in vivo/in vitro experiments demonstrated that MLC activity was inhibited by DPN. For OVX rats with liver cirrhosis, DPN suppressed liver RhoA/ROCK signal, facilitated NO/PKG pathways, and decreased IHVR, giving rise to reduced portal pressure. Therefore, DPN

  12. Molecular Mechanism of Action for Allosteric Modulators and Agonists in CC-chemokine Receptor 5 (CCR5).

    Science.gov (United States)

    Karlshøj, Stefanie; Amarandi, Roxana Maria; Larsen, Olav; Daugvilaite, Viktorija; Steen, Anne; Brvar, Matjaž; Pui, Aurel; Frimurer, Thomas Michael; Ulven, Trond; Rosenkilde, Mette Marie

    2016-12-23

    The small molecule metal ion chelators bipyridine and terpyridine complexed with Zn 2+ (ZnBip and ZnTerp) act as CCR5 agonists and strong positive allosteric modulators of CCL3 binding to CCR5, weak modulators of CCL4 binding, and competitors for CCL5 binding. Here we describe their binding site using computational modeling, binding, and functional studies on WT and mutated CCR5. The metal ion Zn 2+ is anchored to the chemokine receptor-conserved Glu-283 VII:06/7.39 Both chelators interact with aromatic residues in the transmembrane receptor domain. The additional pyridine ring of ZnTerp binds deeply in the major binding pocket and, in contrast to ZnBip, interacts directly with the Trp-248 VI:13/6.48 microswitch, contributing to its 8-fold higher potency. The impact of Trp-248 was further confirmed by ZnClTerp, a chloro-substituted version of ZnTerp that showed no inherent agonism but maintained positive allosteric modulation of CCL3 binding. Despite a similar overall binding mode of all three metal ion chelator complexes, the pyridine ring of ZnClTerp blocks the conformational switch of Trp-248 required for receptor activation, thereby explaining its lack of activity. Importantly, ZnClTerp becomes agonist to the same extent as ZnTerp upon Ala mutation of Ile-116 III:16/3.40 , a residue that constrains the Trp-248 microswitch in its inactive conformation. Binding studies with 125 I-CCL3 revealed an allosteric interface between the chemokine and the small molecule binding site, including residues Tyr-37 I:07/1.39 , Trp-86 II:20/2.60 , and Phe-109 III:09/3.33 The small molecules and CCL3 approach this interface from opposite directions, with some residues being mutually exploited. This study provides new insight into the molecular mechanism of CCR5 activation and paves the way for future allosteric drugs for chemokine receptors. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Correlating gene expression with deformities caused by aryl hydrocarbon receptor agonists in zebrafish (Danio rerio)

    Energy Technology Data Exchange (ETDEWEB)

    Bugiak, B.; Weber, L. [Saskatchewan Univ., Saskatoon, SK (Canada)

    2009-07-01

    Exposure to aryl hydrocarbon receptor (AhR) agonists in fish causes lethal disturbances in fish development, but the effects of acute AhR agonist exposure on the cardiovascular system and deformities remain unclear. This study addressed this issue by performing a series of experiments on zebrafish (Danio rerio). The authors hypothesized that genes needed for cardiovascular regulation (PTGS) would exhibit a stronger link to deformities than detoxification enzymes (CYPs). Zebrafish eggs were exposed aqueously until 4 days post-fertilization (dpf) to the AhR agonists benzo(a)pyrene (BaP) or 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD) alone and in combination with the putative AhR antagonists resveratrol or alpha-naphthoflavone (ANF). Gene expression was measured using real-time, reverse transcriptase PCR in zebrafish at 5 and 10 dpf. Although the mortalities did not differ considerably among groups at 10 dpf, the deformities increased significantly after BaP-ANF at 5 dpf and after BaP at 10 dpf, but not after TCDD treatment. CYP and PTGS isozymes exhibited small, but statistically significant changes at 5 dpf. By 10 dpf, the expression returned to control values. In general, CYP1A and PTGS-1 expression at 5 dpf were positively correlated with deformities, while all other genes were negatively correlated with deformities. It was concluded that changes in CYP1A, CYP1C2, and PTGS-1 gene expression at 5 dpf are associated with developmental deformities, but additional work is needed to determine which has the most important mechanistic link.