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Sample records for competitive receptor antagonist

  1. Discovery and characterization of non-competitive antagonists of group I metabotropic glutamate receptors.

    Science.gov (United States)

    Gasparini, F; Floersheim, P; Flor, P J; Heinrich, M; Inderbitzin, W; Ott, D; Pagano, A; Stierlin, C; Stoehr, N; Vranesic, I; Kuhn, R

    2001-01-01

    We have investigated the mechanism of inhibition of the new group I mGluR antagonists CPCCOEt and MPEP and determined that both compounds have a non-competitive mode of inhibition. Furthermore using chimeric/mutated receptors constructs we have found that these antagonists act at a novel pharmacological site located in the trans-membrane (TM). Specific non-conserved amino acid residues in the TM domain have been identified which are necessary for the inhibition by CPCCOEt and MPEP of the mGlul and mGlu5 receptors, respectively. Using molecular modeling a model of the TM domain was built for both mGlu1 and mGlu5 receptor subtypes. Docking of CPCCOEt and MPEP into their respective model allowed the modelisation of the novel binding site.

  2. Competitive (AP7) and non-competitive (MK-801) NMDA receptor antagonists differentially alter glucose utilization in rat cortex

    Energy Technology Data Exchange (ETDEWEB)

    Clow, D.W.; Lee, S.J.; Hammer, R.P. Jr. (Department of Anatomy and Reproductive Biology, School of Medicine, University of Hawaii, Honolulu (USA))

    1991-04-01

    The effects of D,L-2-amino-7-phosphonoheptanoic acid (AP7), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist, and MK-801, a non-competitive NMDA receptor antagonist, on regional brain metabolism were studied in unanesthetized, freely moving rats by using the quantitative {sup 14}C2-deoxyglucose autoradiographic procedure. AP7 (338 or 901 mg/kg) produced a dose-dependent decrease of metabolic activity throughout most of the regions studied including sensory, motor, and limbic cortices. In contrast, MK-801 (0.1 or 1.0 mg/kg) resulted in a dose-dependent decrease of metabolic activity in sensory cortices, and an increase in limbic regions such as the hippocampal stratum lacunosum moleculare and entorhinal cortex. MK-801 also produced a biphasic response in agranular motor cortex, whereby the low dose increased while the high dose decreased labeling. In addition, MK-801 produced heterogeneous effects on regional cerebral metabolism in sensory cortices. Metabolic activity decreased in layer IV relative to layer Va following MK-801 treatment in primary somatosensory (SI) and visual (VI) cortices, suggesting a shift in activity from afferent fibers innervating layer IV to those innervating layer Va. MK-801 administration also decreased metabolic activity in granular SI relative to dysgranular SI, and in VI relative to secondary visual cortex (VII), thus providing a relative sparing of activity in dysgranular SI and VII. Thus, the non-competitive NMDA receptor antagonist suppressed activity from extrinsic neocortical sources, enhancing relative intracortical activity and stimulating limbic regions, while the competitive NMDA antagonist depressed metabolic activity in all cortical regions.

  3. Development of potent selective competitive-antagonists of the melanocortin type 2 receptor.

    Science.gov (United States)

    Bouw, Elise; Huisman, Martin; Neggers, Sebastian J C M M; Themmen, Axel P N; van der Lely, A J; Delhanty, Patric J D

    2014-08-25

    Cushing's disease, a hypercortisolemic state induced by an ACTH overexpressing pituitary adenoma, causes increased morbidity and mortality. Selective antagonism of the melanocortin type 2 receptor (MC2R) may be a novel treatment modality. Five structurally related peptides with modified HFRW sites but intact putative MC2R binding sites were tested for antagonistic activity at MC1R, MC2R/MRAP, MC3R, MC4R and MC5R. Two of these peptides (GPS1573 and GPS1574) dose-dependently antagonized ACTH-stimulated MC2R activity (IC50s of 66±23 nM and 260±1 nM, respectively). GPS1573 and 1574 suppressed the Rmax but not EC50 of ACTH on MC2R, indicating non-competitive antagonism. These peptides did not antagonize α-MSH stimulation of MC1R and antagonized MC3, 4 and 5R at markedly lower potency. GP1573 and GPS1574 antagonize MC4R with IC50s of 950 nM and 3.7 μM, respectively. In conclusion, two peptide antagonists were developed with selectivity for MC2R, forming a platform for development of a medical treatment for Cushing's disease.

  4. Tying up Nicotine: New Selective Competitive Antagonist of the Neuronal Nicotinic Acetylcholine Receptors

    DEFF Research Database (Denmark)

    Petersen, Ida Nymann; Crestey, François; Jensen, Anders A

    2015-01-01

    Conformational restriction of the pyrrolidine nitrogen in nicotine by the introduction of an ethylene bridge provided a potent and selective antagonist of the α4β2-subtype of the nicotinic acetylcholine receptors. Resolution by chiral SFC, pharmacological characterization of the two enantiomers...

  5. Species-specific action of (Pro3)GIP - an efficacious agonist on human GIP receptor, but partial agonist and competitive antagonist on rat and mouse GIP receptors

    DEFF Research Database (Denmark)

    Sparre-Ulrich, A H; Hansen, Lærke Smidt; Svendsen, B

    2016-01-01

    BACKGROUND AND PURPOSE: Specific high potent receptor antagonists are valuable tools when evaluating animal and human physiology. Within the glucose-dependent insulinotropic polypeptide (GIP) system, considerable attention has been given to the presumed GIP receptor antagonist (Pro3)GIP and its e...... level. Thus, in rodent models human GIP is a comparatively weak partial agonist. Human (Pro3)GIP is not an effective antagonist, so there is still a need for an effective antagonist for the elucidation of GIP's physiology.......BACKGROUND AND PURPOSE: Specific high potent receptor antagonists are valuable tools when evaluating animal and human physiology. Within the glucose-dependent insulinotropic polypeptide (GIP) system, considerable attention has been given to the presumed GIP receptor antagonist (Pro3)GIP and its...... effect in murine studies. We conducted a pharmacological analysis of this ligand including interspecies differences between the rodent and human GIP system. EXPERIMENTAL APPROACH: Transiently transfected COS-7 cells were assessed for cAMP accumulation upon ligand stimulation and assayed in competition...

  6. Synthesis of inositol phosphate-based competitive antagonists of inositol 1,4,5-trisphosphate receptors

    OpenAIRE

    Konieczny, Vera; Stefanakis, John G.; Sitsanidis, Efstratios; Ioannidou, Natalia-Anastasia T.; Papadopoulos, Nikolaos V.; Fylaktakidou, Konstantina C.; Taylor, Colin W.; Koumbis, Alexandros E.

    2016-01-01

    This is the final version of the article. It first appeared from the Royal Chemistry Society via http://dx.doi.org/10.1039/C5OB02623G Inositol 1,4,5-trisphosphate receptors (IP3R) are intracellular Ca²⁺ channels that are widely expressed in animal cells, where they mediate the release of Ca²⁺ from intracellular stores evoked by extracellular stimuli. A diverse array of synthetic agonists of IP3Rs has defined structure-activity relationships, but existing antagonists have severe limitations...

  7. Using the self-administration of apomorphine and cocaine to measure the pharmacodynamic potencies and pharmacokinetics of competitive dopamine receptor antagonists.

    Science.gov (United States)

    Norman, Andrew B; Tabet, Michael R; Norman, Mantana K; Tsibulsky, Vladimir L

    2011-01-15

    Competitive dopamine receptor antagonists accelerate psychomotor stimulant self-administration. According to pharmacological theory of competitive antagonism antagonists raise the equiactive agonist concentration. In the self-administration paradigm this is assumed to be the satiety threshold or C(min). The magnitude of the proportional increase in satiety threshold (agonist concentration ratio) as a function of antagonist dose should reflect the antagonist pharmacodynamic potency. The time course of this effect should reflect the rate of change of antagonist occupancy of receptors and, therefore, antagonist concentration, i.e. pharmacokinetics. Rats self-administered apomorphine or cocaine at a stable rate and were then injected i.v. with one of four competitive D₁-like or D₂-like dopamine receptor antagonists and the session continued. The agonist concentrations at the time of each self-administration (satiety thresholds) were calculated during the session. The antagonists accelerated self-administration of both agonists with a concomitant increase in the calculated satiety thresholds. The maximum agonist concentration ratio was proportional to the dose of antagonist. The time courses of the changes in agonist concentration ratio were independent of the agonist and of the dose of antagonist. Schild analysis of the maximum agonist concentration ratio as a function of the antagonist dose allowed apparent pA₂ (or K(dose)) to be measured. Antagonist K(dose) values should provide a quantitative basis for receptor identification in behavioral pharmacology. The assay system may also measure the pharmacokinetics of antagonist elimination from the brain. Agonist self-administration represents a sensitive in vivo pharmacological assay system that provides information useful for pharmacokinetic/pharmacodynamic modeling of antagonist effects.

  8. The effect of the non-NMDA receptor antagonist GYKI 52466 and NBQX and the competitive NMDA receptor antagonist D-CPPene on the development of amygdala kindling and on amygdala-kindled seizures.

    Science.gov (United States)

    Dürmüller, N; Craggs, M; Meldrum, B S

    1994-02-01

    A competitive (NBQX) and a non-competitive (GYKI 52466) AMPA antagonist, and a competitive NMDA antagonist (D-CPPene) were tested against the development of kindling and against fully kindled seizures in amygdala-kindled rats. GYKI 52466, 10 mg/kg given i.p. 5 min prior to electrical stimulation in fully kindled animals, reduces both the cortical after-discharge duration and the behavioural seizure score. GYKI 52466, 20 mg/kg, reduces seizure score and after-discharge duration significantly (after 5-30 min) but the animals show severe motor side effects and an irregular cortical and hippocampal EEG. Administration of GYKI 52466, 10 mg/kg, prior to kindling stimulation on days 3-8, does not slow the development of kindling. NBQX, 20 mg/kg or 40 mg/kg i.p., 30 min prior to stimulation, significantly reduces the seizure score in fully kindled animals. NBQX 20 mg/kg i.p. has no effect on the development of kindling. D-CPPene, 8 mg/kg or 12 mg/kg, 120 min prior to stimulation reduces the behavioural seizure score in fully kindled animals. D-CPPene, 8 mg/kg on days 3-8, delays the development of kindling. NMDA receptors play a key role in the kindling process. Expression of kindled seizures involves non-NMDA and NMDA receptors.

  9. N- and C-terminally truncated forms of glucose-dependent insulinotropic polypeptide are high-affinity competitive antagonists of the human GIP receptor

    DEFF Research Database (Denmark)

    Hansen, L S; Sparre-Ulrich, A H; Christensen, M.

    2016-01-01

    BACKGROUND AND PURPOSE: Glucose-dependent insulinotropic polypeptide (GIP) impacts lipid, bone, and glucose homeostasis. The GIP receptor belongs to G protein-coupled receptor family B1 and signals through GαS. High affinity ligands for in vivo use are needed to elucidate GIP's physiological...... functions and pharmacological potential. GIP(1-30)NH2 is a naturally occurring truncation of GIP(1-42). Here we characterize eight N-terminal trrncations of human GIP(1-30)NH2 : GIP(2- to 9-30)NH2 . EXPERIMENTAL APPROACH: COS-7 cells were transiently transfected with the human GIP receptor and assessed......, but superior antagonist GIP(3-30)NH2 , that together with GIP(5-30)NH2 were high-affinity competitive antagonist and thus may be suitable tool compounds for basic GIP research and future pharmacological interventions....

  10. Excitatory amino acid receptor antagonists

    DEFF Research Database (Denmark)

    Johansen, T N; Frydenvang, Karla Andrea; Ebert, B

    1997-01-01

    We have previously shown that (RS)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA) is an antagonist at N-methyl-D-aspartic acid (NMDA) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. We have now resolved ATAA via diastereomeric salt formation......)-phenylethylamine salt of N-BOC-(R)-ATAA. Like ATAA, neither (R)- nor (S)-ATAA significantly affected (IC50 > 100 microM) the receptor binding of tritiated AMPA, kainic acid, or (RS)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, the latter being a competitive NMDA antagonist. Electrophysiological experiments......, using the rat cortical wedge preparation, showed the NMDA antagonist effect as well as the AMPA antagonist effect of ATAA to reside exclusively in the (R)-enantiomer (Ki = 75 +/- 5 microM and 57 +/- 1 microM, respectively). Neither (R)- nor (S)-ATAA significantly reduced kainic acid-induced excitation...

  11. NSC23766, a widely used inhibitor of Rac1 activation, additionally acts as a competitive antagonist at muscarinic acetylcholine receptors.

    Science.gov (United States)

    Levay, Magdolna; Krobert, Kurt Allen; Wittig, Karola; Voigt, Niels; Bermudez, Marcel; Wolber, Gerhard; Dobrev, Dobromir; Levy, Finn Olav; Wieland, Thomas

    2013-10-01

    Small molecules interfering with Rac1 activation are considered as potential drugs and are already studied in animal models. A widely used inhibitor without reported attenuation of RhoA activity is NSC23766 [(N(6)-[2-[[4-(diethylamino)-1-methylbutyl]amino]-6-methyl-4-pyrimidinyl]-2-methyl-4,6-quinolinediamine trihydrochloride]. We found that NSC23766 inhibits the M2 muscarinic acetylcholine receptor (M2 mAChR)-induced Rac1 activation in neonatal rat cardiac myocytes. Surprisingly, NSC27366 concomitantly suppressed the carbachol-induced RhoA activation and a M2 mAChR-induced inotropic response in isolated neonatal rat hearts requiring the activation of Rho-dependent kinases. We therefore aimed to identify the mechanisms by which NSC23766 interferes with the differentially mediated, M2 mAChR-induced responses. Interestingly, NSC23766 caused a rightward shift of the carbachol concentration response curve for the positive inotropic response without modifying carbachol efficacy. To analyze the specificity of NSC23766, we compared the carbachol and the similarly Giβγ-mediated, adenosine-induced activation of Gi protein-regulated potassium channel (GIRK) channels in human atrial myocytes. Application of NSC23766 blocked the carbachol-induced K(+) current but had no effect on the adenosine-induced GIRK current. Similarly, an adenosine A1 receptor-induced positive inotropic response in neonatal rat hearts was not attenuated by NSC23766. To investigate its specificity toward the different mAChR types, we studied the carbachol-induced elevation of intracellular Ca(2+) concentrations in human embryonic kidney 293 (HEK-293) cells expressing M1, M2, or M3 mAChRs. NSC23766 caused a concentration-dependent rightward shift of the carbachol concentration response curves at all mAChRs. Thus, NSC23766 is not only an inhibitor of Rac1 activation, but it is within the same concentration range a competitive antagonist at mAChRs. Molecular docking analysis at M2 and M3 mAChR crystal

  12. Altered expression of metabotropic glutamate receptor 1 alpha after acute diffuse brain injury Effect of the competitive antagonist 1-aminoindan-1, 5-dicarboxylic acid

    Institute of Scientific and Technical Information of China (English)

    Fei Cao; Mantao Chen; Gu Li; Ke Ye; Xin Huang; Xiujue Zheng

    2012-01-01

    The diffuse brain injury model was conducted in Sprague-Dawley rats, according to Marmarou's free-fall attack. The water content in brain tissue, expression of metabotropic glutamate receptor 1α mRNA and protein were significantly increased after injury, reached a peak at 24 hours, and then gradually decreased. After treatment with the competitive antagonist of metabotropic glutamate receptor 1α, (RS)-1-aminoindan-1, 5-dicarboxylic acid, the water content of brain tissues decreased between 12-72 hours after injury, and neurological behaviors improved at 2 weeks. These experimental findings suggest that the 1-aminoindan-1, 5-dicarboxylic acid may result in marked neuroprotection against diffuse brain injury.

  13. Non-competitive metabotropic glutamate 1 receptor antagonists block activity of slowly adapting type I mechanoreceptor units in the rat sinus hair follicle.

    Science.gov (United States)

    Cahusac, P M B; Mavulati, S C

    2009-10-20

    Previous studies suggested that Group I metabotropic glutamate (mGlu) receptors play a role in mechanotransduction processes of slowly adapting type I mechanoreceptors. Using an isolated rat sinus hair follicle preparation we tested a range of compounds. Surprisingly, only non-competitive mGlu1 receptor antagonists produced profound and long-lasting depression of mechanically evoked firing. 6-Amino-N-cyclohexyl-N,3-dimethylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (YM-298198) had an IC(50) of 8.7 muM (95% CI 5.7 to 13.2 microM), representing the most potent known blocker of type I mechanoreceptors. The derivative 6-amino-N-cyclohexyl-3-methylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (desmethyl YM-298198) had a comparable potency. Another compound 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) had a similar depressant effect, although it was less potent with an approximate IC(50) of 100 microM. Between three and seven times the concentration of CPCCOEt and YM-298198 respectively was required to produce similar depressions in slowly adapting type II units. No depression, and some weak excitatory effects, were observed using the following ligands: the competitive mGlu1 receptor antagonist alpha-amino-5-carboxy-3-methyl-2-thiopheneacetic acid (3-MATIDA) (300 microM), the phosphoserine phosphatase inhibitor dl-2-amino-3-phosphonopropionic acid (dl-AP3) (2 mM), non-competitive mGlu5 receptor antagonists 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine; (S)-3,5-DHPG, (S)-3,5-dihydroxyphenylglycine (MTEP) (10 microM) and 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) (100 microM), the mGlu1 receptor agonist (S)-3,5-dihydroxyphenylglycine ((S)-3,5-DHPG) (500 microM), and the mGlu5 receptor agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) (1 mM). The results suggest that the non-competitive mGlu1 receptor antagonists are not acting at conventional mGlu1 receptors but at other binding sites, possibly

  14. The Beneficial Effect of Fesoterodine, a Competitive Muscarinic Receptor Antagonist on Erectile Dysfunction in Streptozotocin-induced Diabetic Rats.

    Science.gov (United States)

    Yilmaz-Oral, Didem; Bayatli, Nur; Gur, Serap

    2017-09-01

    To investigate the possible role of fesoterodine (a competitive muscarinic receptor antagonist) on erectile dysfunction in streptozotocin-induced diabetic rats. A total of 16 adult male Sprague-Dawley rats were equally divided into control and diabetic groups. Diabetes was induced by a single intravenous injection of streptozotocin (25-35 mg/kg). In vivo erectile responses were evaluated by the stimulation of cavernosal nerves, and measurements were repeated after the intracavernosal injection of fesoterodine (1 µM) in rats. The relaxation responses to fesoterodine were examined via incubation with various inhibitors. The relaxant responses of corpus cavernosum (CC) strips were observed in the presence or the absence of fesoterodine (10 µM). Intracavernous administration of fesoterodine restored in vivo erectile response at 5.0- and 7.5-V levels, except for 2.5 V in diabetic rats. Basal intracavernosal pressure (5.4 ± 0.9 mm Hg) in diabetic rats was markedly increased after injection of fesoterodine (33.9 ± 7.9 mm Hg, P fesoterodine resulted in a relaxation of CC in a concentration-dependent manner, which was reduced in diabetic rats. Nifedipine (l-type Ca(2+) channel blocker) inhibited maximum fesoterodine-induced relaxation by 58%. The nonselective K(+) channel blocker tetraethylammonium and glibenclamide incubation did not change the relaxant response to fesoterodine. The relaxant responses to acetylcholine (10 µM), electrical field stimulation (10 Hz), and sodium nitroprusside (0.01 µM) in diabetic rats were increased after incubation with fesoterodine (10 µM). Fesoterodine improved erectile function and relaxation of isolated strips of rat CC. The underlying mechanism of fesoterodine is likely due to the blocking of l-type calcium channels independent of the nitric oxide-cyclic guanosine monophosphate pathway. Further investigations are warranted to fully elucidate the restorative effects of fesoterodine on overactive

  15. 4,5-Substituted 3-Isoxazolols with Insecticidal Activity Act as Competitive Antagonists of Housefly GABA Receptors.

    Science.gov (United States)

    Liu, Genyan; Ozoe, Fumiyo; Furuta, Kenjiro; Ozoe, Yoshihisa

    2015-07-22

    The insect GABA receptor (GABAR), which is composed of five RDL subunits, represents an important target for insecticides. A series of 4,5-disubstituted 3-isoxazolols, including muscimol analogues, were synthesized and examined for their activities against four splice variants (ac, ad, bc, and bd) of housefly GABARs expressed in Xenopus oocytes. Muscimol was a more potent agonist than GABA in all four splice variants, whereas synthesized analogues did not exhibit agonism but rather antagonism in housefly GABARs. The introduction of bicyclic aromatic groups at the 4-position of muscimol and the simultaneous replacement of the aminomethyl group with a carbamoyl group at the 5-position to afford six 4-aryl-5-carbamoyl-3-isoxazolols resulted in compounds that exhibited significantly enhanced antagonism with IC50 values in the low micromolar range in the ac variant. The inhibition of GABA-induced currents by 100 μM analogues was approximately 1.5-4-fold greater in the ac and bc variants than in the ad and bd variants. 4-(3-Biphenylyl)-5-carbamoyl-3-isoxazolol displayed competitive antagonism, with IC50 values of 30, 34, 107, and 96 μM in the ac, bc, ad, and bd variants, respectively, and exhibited moderate insecticidal activity against houseflies, with an LD50 value of 5.6 nmol/fly. These findings suggest that these 3-isoxazolol analogues are novel lead compounds for the design and development of insecticides that target the orthosteric site of housefly GABARs.

  16. The non-competitive acetylcholinesterase inhibitor APS12-2 is a potent antagonist of skeletal muscle nicotinic acetylcholine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Grandič, Marjana [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia); Aráoz, Romulo; Molgó, Jordi [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Turk, Tom; Sepčić, Kristina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana (Slovenia); Benoit, Evelyne [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Frangež, Robert, E-mail: robert.frangez@vf.uni-lj.si [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia)

    2012-12-01

    APS12-2, a non-competitive acetylcholinesterase inhibitor, is one of the synthetic analogs of polymeric alkylpyridinium salts (poly-APS) isolated from the marine sponge Reniera sarai. In the present work the effects of APS12-2 were studied on isolated mouse phrenic nerve–hemidiaphragm muscle preparations, using twitch tension measurements and electrophysiological recordings. APS12-2 in a concentration-dependent manner blocked nerve-evoked isometric muscle contraction (IC{sub 50} = 0.74 μM), without affecting directly-elicited twitch tension up to 2.72 μM. The compound (0.007–3.40 μM) decreased the amplitude of miniature endplate potentials until a complete block by concentrations higher than 0.68 μM, without affecting their frequency. Full size endplate potentials, recorded after blocking voltage-gated muscle sodium channels, were inhibited by APS12-2 in a concentration-dependent manner (IC{sub 50} = 0.36 μM) without significant change in the resting membrane potential of the muscle fibers up to 3.40 μM. The compound also blocked acetylcholine-evoked inward currents in Xenopus oocytes in which Torpedo (α1{sub 2}β1γδ) muscle-type nicotinic acetylcholine receptors (nAChRs) have been incorporated (IC{sub 50} = 0.0005 μM), indicating a higher affinity of the compound for Torpedo (α1{sub 2}β1γδ) than for the mouse (α1{sub 2}β1γε) nAChR. Our data show for the first time that APS12-2 blocks neuromuscular transmission by a non-depolarizing mechanism through an action on postsynaptic nAChRs of the skeletal neuromuscular junction. -- Highlights: ► APS12-2 produces concentration-dependent inhibition of nerve-evoked muscle contraction in vitro. ► APS12-2 blocks MEPPs and EPPs at the neuromuscular junction. APS12-2 blocks ACh-activated current in Xenopus oocytes incorporated with Torpedo nAChRs.

  17. 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.

  18. Blocking S1P interaction with S1P{sub 1} receptor by a novel competitive S1P{sub 1}-selective antagonist inhibits angiogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Yasuyuki, E-mail: y.fujii@po.rd.taisho.co.jp [Department of Molecular Function and Pharmacology Laboratories, Taisho Pharmaceutical Co. Ltd., 1-403 Saitama, Saitama 331-9530 (Japan); Ueda, Yasuji; Ohtake, Hidenori; Ono, Naoya; Takayama, Tetsuo; Nakazawa, Kiyoshi [Department of Molecular Function and Pharmacology Laboratories, Taisho Pharmaceutical Co. Ltd., 1-403 Saitama, Saitama 331-9530 (Japan); Igarashi, Yasuyuki [Laboratory of Biomembrane and Biofunctional Chemistry, Hokkaido University, Sapporo, Hokkaido 060-0812 (Japan); Goitsuka, Ryo [Division of Development and Aging, Research Institute for Biological Sciences, Tokyo University of Science, Noda, Chiba 278-0022 (Japan)

    2012-03-23

    Highlights: Black-Right-Pointing-Pointer The effect of a newly developed S1P{sub 1}-selective antagonist on angiogenic responses. Black-Right-Pointing-Pointer S1P{sub 1} is a critical component of VEGF-related angiogenic responses. Black-Right-Pointing-Pointer S1P{sub 1}-selective antagonist showed in vitro activity to inhibit angiogenesis. Black-Right-Pointing-Pointer S1P{sub 1}-selective antagonist showed in vivo activity to inhibit angiogenesis. Black-Right-Pointing-Pointer The efficacy of S1P{sub 1}-selective antagonist for anti-cancer therapies. -- Abstract: Sphingosine 1-phosphate receptor type 1 (S1P{sub 1}) was shown to be essential for vascular maturation during embryonic development and it has been demonstrated that substantial crosstalk exists between S1P{sub 1} and other pro-angiogenic growth factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor. We developed a novel S1P{sub 1}-selective antagonist, TASP0277308, which is structurally unrelated to S1P as well as previously described S1P{sub 1} antagonists. TASP0277308 inhibited S1P- as well as VEGF-induced cellular responses, including migration and proliferation of human umbilical vein endothelial cells. Furthermore, TASP0277308 effectively blocked a VEGF-induced tube formation in vitro and significantly suppressed tumor cell-induced angiogenesis in vivo. These findings revealed that S1P{sub 1} is a critical component of VEGF-related angiogenic responses and also provide evidence for the efficacy of TASP0277308 for anti-cancer therapies.

  19. Benzodiazepine receptor antagonists for hepatic encephalopathy

    DEFF Research Database (Denmark)

    Als-Nielsen, B; Gluud, L L; Gluud, C

    2004-01-01

    Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.......Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy....

  20. Effects of the non-competitive NMDA receptor antagonist memantine on the volitional consumption of ethanol by alcohol-preferring rats.

    Science.gov (United States)

    Malpass, Gloria E; Williams, Helen L; McMillen, Brian A

    2010-05-01

    Potent N-methyl-d-aspartate (NMDA) receptor antagonists decrease volitional consumption of ethanol by rats. This study examined the effects of memantine, a low-affinity, open channel NMDA antagonist, on volitional consumption of ethanol by alcohol-preferring rats and potential locomotor, sedative and hypothermic effects. Volitional consumption of ethanol in a 24-hr two-choice paradigm was determined for male Myers' high-ethanol-preferring (mHEP) rats. Effects of memantine (0.3, 1.0, 3.0 and 10.0 mg/kg, i.p., b.i.d. [twice daily] for 3 days) or vehicle on volitional consumption of ethanol, proportion of ethanol to total fluids consumed, total fluid intake and consumption of food were observed. Potential sedating and locomotor effects of memantine (10.0 mg/kg, i.p., b.i.d.) were determined using an elevated plus maze and an Auto-Track Opto-Varimex activity monitoring system. Rectal temperature was measured to determine if memantine (10.0 mg/kg, i.p.) produces a hypothermic effect. The results indicate that memantine dose-dependently decreased the amount of ethanol and proportion of ethanol to total fluids consumed daily, reaching 48% and 24%, respectively, at the highest dose. These effects did not appear to be anti-caloric. Memantine (10.0 mg/kg) partially reversed both the sedation and the reductions in locomotor activity induced by ethanol. This dose did, however, produce a small, partially reversible hypothermic effect. In conclusion, memantine may decrease ethanol consumption with fewer side effects than other NMDA receptor antagonists, such as phencyclidine (PCP), MK 801 and ketamine.

  1. Therapeutic window of opportunity for the neuroprotective effect of valproate versus the competitive AMPA receptor antagonist NS1209 following status epilepticus in rats.

    Science.gov (United States)

    Langer, Melanie; Brandt, Claudia; Zellinger, Christina; Löscher, Wolfgang

    2011-01-01

    Epileptogenesis, i.e., the process leading to epilepsy, is a presumed consequence of brain insults including head trauma, stroke, infections, tumors, status epilepticus (SE), and complex febrile seizures. Typically, brain insults produce morphological and functional alterations in the hippocampal formation, including neurodegeneration in CA1, CA3, and, most consistently, the dentate hilus. Most of these alterations develop gradually, over several days, after the insult, providing a therapeutic window of opportunity for neuroprotective agents in the immediate post-injury period. We have previously reported that prolonged (four weeks) treatment with the antiepileptic drug valproate (VPA) after SE prevents hippocampal damage and most of the behavioral alterations that occur after brain insult, but not the development of spontaneously occurring seizures. These data indicated that VPA, although not preventing epilepsy, might be an effective disease-modifying treatment following brain insult. The present study was designed to (1) determine the therapeutic window for the neuroprotective effect of VPA after SE; (2) compare the efficacy of different intermittent i.p. versus continuous i.v. VPA treatment protocols; and (3) compare VPA with the glutamate (AMPA) receptor antagonist NS1209. As in our previous study with VPA, SE was induced by sustained electrical stimulation of the basolateral amygdala in rats and terminated after 4 h by diazepam. In vehicle controls, >90% of the animals developed significant neurodegeneration in the dentate hilus, whereas damage in CA1 and CA3 was more variable. Hilar parvalbumin-expressing interneurons were more sensitive to the effects of seizures than somatostatin-stained hilar interneurons or hilar mossy cells. Among the various VPA treatment protocols, continuous infusion of VPA for 24 immediately following the SE was the most effective neuroprotective treatment, preventing most of the neuronal damage. Infusion with NS1209 for 24 h

  2. Antagonistic competition moderates virulence in Bacillus thuringiensis.

    Science.gov (United States)

    Garbutt, Jennie; Bonsall, Michael B; Wright, Denis J; Raymond, Ben

    2011-08-01

    Classical models of the evolution of virulence predict that multiple infections should select for elevated virulence, if increased competitiveness arises from faster growth. However, diverse modes of parasite competition (resource-based, antagonism, immunity manipulation) can lead to adaptations with different implications for virulence. Using an experimental evolution approach we investigated the hypothesis that selection in mixed-strain infections will lead to increased antagonism that trades off against investment in virulence. Selection in mixed infections led to improved suppression of competitors in the bacterial insect pathogen Bacillus thuringiensis. Increased antagonism was associated with decreased virulence in three out of four selected lines. Moreover, mixed infections were less virulent than single-strain infections, and between-strain competition tended to decrease pathogen growth in vivo and in vitro. Spiteful interactions among these bacteria may be favoured because of the high metabolic costs of virulence factors and the high risk of mixed infections.

  3. Why are mineralocorticoid receptor antagonists cardioprotective?

    NARCIS (Netherlands)

    W. Chai (Wenxia); A.H.J. Danser (Jan)

    2006-01-01

    textabstractTwo clinical trials, the Randomized ALdosterone Evaluation Study (RALES) and the EPlerenone HEart failure and SUrvival Study (EPHESUS), have recently shown that mineralocorticoid receptor (MR) antagonists reduce mortality in patients with heart failure on top of ACE inhibition. This effe

  4. GABAA receptor partial agonists and antagonists

    DEFF Research Database (Denmark)

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

    2015-01-01

    A high degree of structural heterogeneity of the GABAA receptors (GABAARs) has been revealed and is reflected in multiple receptor subtypes. The subunit composition of GABAAR subtypes is believed to determine their localization relative to the synapses and adapt their functional properties...... 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...

  5. EFFECT OF ANGIOTENSIN II RECEPTOR ANTAGONIST AND ENDOTHELIN RECEPTOR ANTAGONIST ON NITROGLYCERIN TOLERANCE IN RATS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective. To investigate whether angiotensin II receptor antagonist and endothelin receptor antagonist can improve the nitroglycerin (Nit) tolerance in vivo. Methods. Twenty-four rats were divided into 4 groups (n=6,each): Control group, Nitroglycerin (Nit) group, Nit+ bosentan group and Nit+ losartan group. Nitroglycerin tolerance was induced by 2-day treatment of nitroglycerin patch (0.05 mg/h). AngiotensinⅡ receptor antagonist losartan ( 10 mg· kg- 1· d- 1 ) and endothelin receptor antagonist bosentan ( 100 mg· kg- 1· d- 1 ) were given by gavage for 2 days respectively. Results. The least hypotensive response to sodium nitroprusside (SNP) was observed in Nit group . The effective percentages of hypotensive response to SNP were increased in both Nit+ losartan group and Nit+ bosentan group compared with Nit group [(31.95± 4.45 ) % vs (21.00± 3.69 ) % , P Conclusion. Endothelin receptor antagonist and angiotensin Ⅱ receptor antagonist could prevent against the Nit tolerance .

  6. Continuous intracerebroventricular infusion of the competitive NMDA receptor antagonist, LY235959, facilitates escalation of cocaine self-administration and increases break point for cocaine in Sprague-Dawley rats.

    Science.gov (United States)

    Allen, Richard M; Uban, Kristina A; Atwood, Elizabeth M; Albeck, David S; Yamamoto, Dorothy J

    2007-11-01

    Although escalation of consumption is an important characteristic of cocaine dependence, the neurobiological mechanisms that mediate this phenomenon have not been fully described. In this study, we used male, Sprague-Dawley rats to measure the effects of acute and continuous intracerebroventricular (ICV) administration of the competitive NMDA receptor antagonist, LY235959, on cocaine self-administration behavior under various schedules of reinforcement and access conditions. Single ICV infusions of LY235959 (0.03-0.3 microg/5 microl) produced dose-dependent and statistically significant decreases in the number of cocaine infusions earned under a progressive ratio schedule of reinforcement. In a second experiment, vehicle or LY235959 (0.2-0.3 microg/day) was continuously administered ICV to rats via surgically-implanted subcutaneous osmotic minipump/intracranial cannula assemblies. Both vehicle- and LY235959-treated rats significantly escalated cocaine self-administration over the 10 long access sessions; however, rats treated with LY235959 escalated cocaine self-administration faster and to a greater degree than vehicle-treated rats. There was a statistically significant increase in cocaine infusions earned under the PR schedule in LY235959-treated rats, but not vehicle-treated rats, after 10 long access cocaine self-administration sessions. These data support the hypothesis that escalation of cocaine consumption is mediated by hypo-glutamatergic tone in the central nervous system and this facilitation of escalation is associated with an increase in motivation to respond for cocaine.

  7. ETA-receptor antagonists or allosteric modulators?

    DEFF Research Database (Denmark)

    De Mey, Jo G R; Compeer, Matthijs G; Lemkens, Pieter

    2011-01-01

    The paracrine signaling peptide endothelin-1 (ET1) is involved in cardiovascular diseases, cancer and chronic pain. It acts on class A G-protein-coupled receptors (GPCRs) but displays atypical pharmacology. It binds tightly to ET receptor type A (ET(A)) and causes long-lasting effects. In resista......The paracrine signaling peptide endothelin-1 (ET1) is involved in cardiovascular diseases, cancer and chronic pain. It acts on class A G-protein-coupled receptors (GPCRs) but displays atypical pharmacology. It binds tightly to ET receptor type A (ET(A)) and causes long-lasting effects....... In resistance arteries, the long-lasting contractile effects can only be partly and reversibly relaxed by low-molecular-weight ET(A) antagonists (ERAs). However, the neuropeptide calcitonin-gene-related peptide selectively terminates binding of ET1 to ET(A). We propose that ET1 binds polyvalently to ET(A......) and that ERAs and the physiological antagonist allosterically reduce ET(A) functions. Combining the two-state model and the two-domain model of GPCR function and considering receptor activation beyond agonist binding might lead to better anti-endothelinergic drugs. Future studies could lead to compounds...

  8. Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists.

    Science.gov (United States)

    Hansen, Kasper B; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L; Yuan, Hongjie; Vance, Katie M; Orr, Anna G; Kvist, Trine; Ogden, Kevin K; Le, Phuong; Vellano, Kimberly M; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T J; Snyder, James P; Bräuner-Osborne, Hans; Traynelis, Stephen F

    2010-06-01

    N-Methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca(2+)-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism.

  9. A synthetic peptide derivative that is a cholecystokinin receptor antagonist.

    Science.gov (United States)

    Lignon, M F; Galas, M C; Rodriguez, M; Laur, J; Aumelas, A; Martinez, J

    1987-05-25

    So far, there are no known peptidic effective receptor antagonists of both peripheral and central effects of cholecystokinin (CCK). Here, we describe a synthetic peptide derivative of CCK, t-butyloxycarbonyl-Tyr(SO3-)-Met-Gly-D-Trp-Nle-Asp 2-phenylethyl ester 1 (where Nle is norleucine), which is a potent CCK receptor antagonist. In rat and guinea pig dispersed pancreatic acini, this peptide derivative did not alter amylase secretion, but was able to antagonize the stimulation caused by cholecystokinin-related agonists. It caused a parallel rightward shift in the dose-response curve for the stimulation of amylase secretion with half-maximal inhibition of CCK-8-stimulated amylase release at a concentration of about 0.1 microM. Compound 1 was able to inhibit the binding of labeled CCK-9 (the C-terminal nonapeptide of CCK) to rat and guinea pig pancreatic acini (IC50 = 5 X 10(-8) M) as well as to guinea pig cerebral cortical membranes (IC50 = 5 X 10(-7) M). These results indicate that Compound 1 is a potent competitive CCK receptor antagonist.

  10. Phenylthiophenecarboxamide antagonists of the olfactory receptor co-receptor subunit from a mosquito.

    Directory of Open Access Journals (Sweden)

    Sisi Chen

    Full Text Available Insects detect environmental chemicals using chemosensory receptors, such as the ORs, a family of odorant-gated ion channels. Insect ORs are multimeric complexes of unknown stoichiometry, formed by a common subunit (the odorant receptor co-receptor subunit, Orco and one of many variable subunits that confer odorant specificity. The recent discovery of Orco directed ligands, including both agonists and antagonists, suggests Orco as a promising target for chemical control of insects. In addition to competitively inhibiting OR activation by Orco agonists, several Orco antagonists have been shown to act through a non-competitive mechanism to inhibit OR activation by odorants. We previously identified a series of Orco antagonists, including N-(4-ethylphenyl-2-thiophenecarboxamide (OX1a, previously referred to as OLC20. Here, we explore the chemical space around the OX1a structure to identify more potent Orco antagonists. Cqui\\Orco+Cqui\\Or21, an OR from Culex quinquefasciatus (the Southern House Mosquito that responds to 3-methylindole (skatole and is thought to mediate oviposition behavior, was expressed in Xenopus oocytes and receptor function assayed by two-electrode voltage clamp electrophysiology. 22 structural analogs of OX1a were screened for antagonism of OR activation by an Orco agonist. By varying the moieties decorating the phenyl and thiophene rings, and altering the distance between the rings, we were able to identify antagonists with improved potency. Detailed examination of three of these compounds (N-mesityl-2-thiophenecarboxamide, N-(4-methylbenzyl-2-thiophenecarboxamide and N-(2-ethylphenyl-3-(2-thienyl-2-propenamide demonstrated competitive inhibition of receptor activation by an Orco agonist and non-competitive inhibition of receptor activation by an odorant. The ability to inhibit OR activation by odorants may be a general property of this class of Orco antagonist, suggesting that odorant mediated behaviors can be manipulated

  11. Antagonistic action of pitrazepin on human and rat GABAA receptors

    Science.gov (United States)

    Demuro, Angelo; Martinez-Torres, Ataulfo; Francesconi, Walter; Miledi, Ricardo

    1999-01-01

    Pitrazepin, 3-(piperazinyl-1)-9H-dibenz(c,f) triazolo(4,5-a)azepin is a piperazine antagonist of GABA in a variety of electrophysiological and in vitro binding studies involving GABA and glycine receptors. In the present study we have investigated the effects of pitrazepin, and the GABAA antagonist bicuculline, on membrane currents elicited by GABA in Xenopus oocytes injected with rat cerebral cortex mRNA or cDNAs encoding α1β2 or α1β2γ2S human GABAA receptor subunits.The three types of GABAA receptors expressed were reversibly antagonized by bicuculline and pitrazepin in a concentration-dependent manner. GABA dose-current response curves for the three types of receptors were shifted to the right, in a parallel manner, by increasing concentrations of pitrazepin.Schild analyses gave pA2 values of 6.42±0.62, n=4, 6.41±1.2, n=5 and 6.21±1.24, n=6, in oocytes expressing rat cerebral cortex, α1β2 or α1β2γ2S human GABAA receptors respectively (values are given as means±s.e.mean), and the Hill coefficients were all close to unity. All this is consistent with the notion that pitrazepin acts as a competitive antagonist of these GABAA receptors; and that their antagonism by pitrazepin is not strongly dependent on the subunit composition of the receptors here studied.Since pitrazepin has been reported to act also at the benzodiazepine binding site, we studied the effect of the benzodiazepine antagonist Ro 15-1788 (flumazenil) on the inhibition of α1β2γ2S receptors by pitrazepin. Co-application of Ro 15-1788 did not alter the inhibiting effect of pitrazepin. Moreover, pitrazepin did not antagonize the potentiation of GABA-currents by flunitrazepam. All this suggests that pitrazepin does not affect the GABA receptor-chloride channel by interacting with the benzodiazepine receptor site. PMID:10369456

  12. Microinfusion of the non-competitive N-methyl-D-aspartate receptor antagonist MK-801 (dizocilpine) into the dorsal hippocampus of wistar rats does not affect latent inhibition and prepulse inhibition, but increases startle reaction and locomotor activity.

    Science.gov (United States)

    Zhang, W N; Bast, T; Feldon, J

    2000-01-01

    Latent inhibition (the retarded conditioning to a stimulus following its repeated non-reinforced pre-exposure) and prepulse inhibition (the reduction in the startle response to an intense acoustic stimulus when this stimulus is immediately preceded by a prepulse) reflect cognitive and sensorimotor gating processes, respectively, and are deficient in schizophrenic patients. The disruption of latent inhibition and prepulse inhibition in the rat is used as an animal model for the attentional deficits associated with schizophrenia. The present study tested the extent to which latent inhibition and prepulse inhibition, startle reaction and locomotor activity in the open field were affected by infusing the non-competitive N-methyl-D-aspartate receptor antagonist MK-801 (dizocilpine) into the dorsal hippocampus of Wistar rats. We used the same dose of MK-801 (6.25microg/0.5microl per side) previously found to be effective in the disruption of prepulse inhibition when infused into the dorsal hippocampus of Sprague-Dawley rats [Bakshi V. P. and Geyer M. A. (1998) J. Neurosci. 18, 8394-8401; Bakshi V. P. and Geyer M. A. (1999) Neuroscience 92, 113-121]. Bilateral infusion of MK-801 into the dorsal hippocampus did not disrupt latent inhibition. Furthermore, in contrast to previous studies, we failed to find a significant disruption of prepulse inhibition after MK-801 infusion into the dorsal hippocampus, although MK-801 infusion was effective in increasing the startle amplitude as well as locomotor activity in an open field. From our results, we suggest that N-methyl-D-aspartate receptor-mediated processes within the dorsal hippocampus are not necessary for the normal maintenance of the attentional processes reflected by latent inhibition and prepulse inhibition.

  13. Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists.

    Science.gov (United States)

    Ajram, Laura; Begg, Malcolm; Slack, Robert; Cryan, Jenni; Hall, David; Hodgson, Simon; Ford, Alison; Barnes, Ashley; Swieboda, Dawid; Mousnier, Aurelie; Solari, Roberto

    2014-04-15

    The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

  14. Mineralocorticoid and glucocorticoid receptor antagonists in animal models of anxiety

    NARCIS (Netherlands)

    Korte, SM; KorteBouws, GAH; Koob, GF; DeKloet, ER; Bohus, B

    1996-01-01

    The behavioral effects of intracerebroventricular (ICV) administration of a specific mineralocorticoid receptor (MR) antagonist [RU28318 (10-50 ng/2 mu l)], a glucocorticoid receptor (GR) antagonist [RU38486 (1-50 ng/2 mu l)], or both antagonists (50 ng/2 mu l), were studied in two different animal

  15. EFFECT OF ANGIOTENSIN II RECEPTOR ANTAGONIST AND ENDOTHELIN RECEPTOR ANTAGONIST ON NITROGLYCERIN TOLERANCE IN RATS

    Institute of Scientific and Technical Information of China (English)

    张建梅; 陈永红; 王晓红; 唐朝枢

    2001-01-01

    Objective. To investigate whether angiotensin II receptor antagonist and endothelin receptor antagonist can improve the nitroglycerin (Nit) tolerance in vivo. Methods. Twenty-four rats were divided into 4 groups (n =6, each): Control group, Nitroglycerin (Nit) group, Nit + bosentan group and Nit + losartan group. Nitroglycerin tolerance was induced by 2-day treatment ofnitroglycerin patch (0. 05mg/h). Angiotensin I1 receptor antagonist losartan (10mg ·kg-1·d-1) and endothe-lin receptor antagonist bosentan ( 100 mg·kg-1· d-1 ) were given by gavage for 2 days respectively. Results. The least hypotensive response to sodium nitroprusside (SNP) was observed in Nit group. The effec-tive percentages of hypotensive response to SNP were increased in both Nit + losartan group and Nit + bosentangroup compared with Nit group [(31.95±4.45) % vs (21.00±3.69) %, P <0.01and (33. 18±6. 16)% vs (21.00±3.69 ) %, P < 0. 01 , respectivelyl. The maximal vessel relaxation induced by SNP was thesame in 4 different groups but the highest EC50 (concentration which produces 50% of the maximal response toSNP) was found in tolerant group[ (34 ±10) nmol/L, P < 0. 01 ]. The ET-1 amounts in plasma and vasculartissue were markedly increased by 54% and 60% in Nit group compared with those in control group( P<0. 01). The ET-1 amounts in plasma and vascular tissue were decreased by 30% and 37% in Nit + losartangroup compared with those in Nit group ( P < 0.01 ). Conclusion. Endothelin receptor antagonist and angiotensin Ⅱ receptor antagonist could prevent against the Nit tolerance.

  16. The use of organotypic hippocampal slice cultures to evaluate protection by non-competitive NMDA receptor antagonists against excitotoxicity

    DEFF Research Database (Denmark)

    Ring, Avi; Tanso, Rita; Noraberg, Jens

    2010-01-01

    There is a wide interest in testing neuroprotectants which inhibit the neurodegeneration that results from excessive activation of brain NMDA receptors.  As an alternative to in vivo testing in animal models we demonstrate here the use of a complex in vitro model to compare the efficacy...... with in vivo tests in rodents . We conclude that the slice culture model provides valuable pre-clinical data and applying the model to screen neuroprotectants may significantly limit the use of in vivo tests in animals....... blockers that inhibit excitotoxic injury and their neuroprotective capacity have been extensively investigated in vivo in animal models. They have also been evaluated as potential countermeasure agents against organophosphate poisoning. Quantitative densitometric image analysis of propidium iodide uptake...

  17. Characterization of a novel non-steroidal glucocorticoid receptor antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qun-Yi; Zhang, Meng [The National Center for Drug Screening, Shanghai (China); State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai (China); Hallis, Tina M.; DeRosier, Therese A. [Cell Systems Division, Invitrogen, Madison, WI (United States); Yue, Jian-Min; Ye, Yang [State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai (China); Mais, Dale E. [The National Center for Drug Screening, Shanghai (China); MPI Research, Mattawan, MI (United States); Wang, Ming-Wei, E-mail: wangmw@mail.shcnc.ac.cn [The National Center for Drug Screening, Shanghai (China); State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai (China)

    2010-01-15

    Selective antagonists of the glucocorticoid receptor (GR) are desirable for the treatment of hypercortisolemia associated with Cushing's syndrome, psychic depression, obesity, diabetes, neurodegenerative diseases, and glaucoma. NC3327, a non-steroidal small molecule with potent binding affinity to GR (K{sub i} = 13.2 nM), was identified in a high-throughput screening effort. As a full GR antagonist, NC3327 greatly inhibits the dexamethasone (Dex) induction of marker genes involved in hepatic gluconeogenesis, but has a minimal effect on matrix metalloproteinase 9 (MMP-9), a GR responsive pro-inflammatory gene. Interestingly, the compound recruits neither coactivators nor corepressors to the GR complex but competes with glucocorticoids for the interaction between GR and a coactivator peptide. Moreover, NC3327 does not trigger GR nuclear translocation, but significantly blocks Dex-induced GR transportation to the nucleus, and thus appears to be a 'competitive' GR antagonist. Therefore, the non-steroidal compound, NC3327, may represent a new class of GR antagonists as potential therapeutics for a variety of cortisol-related endocrine disorders.

  18. Pharmacology of glutamate receptor antagonists in the kindling model of epilepsy.

    Science.gov (United States)

    Löscher, W

    1998-04-01

    It is widely accepted that excitatory amino acid transmitters such as glutamate are involved in the initiation of seizures and their propagation. Most attention has been directed to synapses using NMDA receptors, but more recent evidence indicates potential roles for ionotropic non-NMDA (AMPA/kainate) and metabotropic glutamate receptors as well. Based on the role of glutamate in the development and expression of seizures, antagonism of glutamate receptors has long been thought to provide a rational strategy in the search for new, effective anticonvulsant drugs. Furthermore, because glutamate receptor antagonists, particularly those acting on NMDA receptors, protect effectively in the induction of kindling, it was suggested that they may have utility in epilepsy prophylaxis, for example, after head trauma. However, first clinical trials with competitive and uncompetitive NMDA receptor antagonists in patients with partial (focal) seizures, showed that these drugs lack convincing anticonvulsant activity but induce severe neurotoxic adverse effects in doses which were well tolerated in healthy volunteers. Interestingly, the only animal model which predicted the unfavorable clinical activity of competitive NMDA antagonists in patients with chronic epilepsy was the kindling model of temporal lobe epilepsy, indicating that this model should be used in the search for more effective and less toxic glutamate receptor antagonists. In this review, results from a large series of experiments on different categories of glutamate receptor antagonists in fully kindled rats are summarized and discussed. NMDA antagonists, irrespective whether they are competitive, high- or low-affinity uncompetitive, glycine site or polyamine site antagonists, do not counteract focal seizure activity and only weakly, if at all, attenuate propagation to secondarily generalized seizures in this model, indicating that once kindling is established, NMDA receptors are not critical for the expression of

  19. HIGH AFFINITY ACYLATING ANTAGONISTS FOR MUSCARINIC RECEPTORS

    Science.gov (United States)

    Baumgold, Jesse; Karton, Yishai; Malka, Naftali; Jacobson, Kenneth A.

    2012-01-01

    Summary The muscarinic antagonists pirenzepine and telenzepine were derivitized as alkylamino derivatives at a site on the molecules corresponding to a region of bulk tolerance in receptor binding. The distal primary amino groups were coupled to the cross-linking reagent meta-phenylene diisothiocyanate, resulting in two isothiocyanate derivatives that were found to inhibit muscarinic receptors irreversibly and in a dose-dependent fashion. Preincubation of rat forebrain membranes with an isothiocyanate derivative followed by radioligand binding using [3H]N-methylscopolamine diminished the Bmax value, but did not affect the Kd value. The receptor binding site was not restored upon repeated washing, indicating that irreversible inhibition had occurred. IC50 values for the irreversible inhibition at rat forebrain muscarinic receptors were 0.15 nM and 0.19 nM, for derivatives of pirenzepine and telenzepine, respectively. The isothiocyanate derivative of pirenzepine was non-selective as an irreversible muscarinic inhibitor, and the corresponding derivative prepared from telenzepine was 5-fold selective for forebrain (mainly m1) vs. heart (m2) muscarinic receptors. PMID:1625525

  20. High affinity retinoic acid receptor antagonists: analogs of AGN 193109.

    Science.gov (United States)

    Johnson, A T; Wang, L; Gillett, S J; Chandraratna, R A

    1999-02-22

    A series of high affinity retinoic acid receptor (RAR) antagonists were prepared based upon the known antagonist AGN 193109 (2). Introduction of various phenyl groups revealed a preference for substitution at the para-position relative to the meta-site. Antagonists with the highest affinities for the RARs possessed hydrophobic groups, however, the presence of polar functionality was also well tolerated.

  1. Anti-idiotypic antibody: A new strategy for the development of a growth hormone receptor antagonist.

    Science.gov (United States)

    Lan, Hainan; Zheng, Xin; Khan, Muhammad Akram; Li, Steven

    2015-11-01

    In general, traditional growth hormone receptor antagonist can be divided into two major classes: growth hormone (GH) analogues and anti-growth hormone receptor (GHR) antibodies. Herein, we tried to explore a new class of growth hormone receptor (GHR) antagonist that may have potential advantages over the traditional antagonists. For this, we developed a monoclonal anti-idiotypic antibody growth hormone, termed CG-86. A series of experiments were conducted to characterize and evaluate this antibody, and the results from a competitive receptor-binding assay, Enzyme Linked Immunosorbent Assays (ELISA) and epitope mapping demonstrate that CG-86 behaved as a typical Ab2β. Next, we examined its antagonistic activity using in vitro cell models, and the results showed that CG-86 could effectively inhibit growth hormone receptor-mediated signalling and effectively inhibit growth hormone-induced Ba/F3-GHR638 proliferation. In summary, these studies show that an anti-idiotypic antibody (CG-86) has promise as a novel growth hormone receptor antagonist. Furthermore, the current findings also suggest that anti-idiotypic antibody may represent a novel strategy to produce a new class of growth hormone receptor antagonist, and this strategy may be applied with other cytokines or growth factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Synthesis and pharmacological evaluation of DHβE analogs as neuronal nicotinic acetylcholine receptor antagonists

    DEFF Research Database (Denmark)

    Jepsen, Tue H.; Jensen, Anders A.; Lund, Mads Henrik;

    2014-01-01

    Dihydro-β-erythroidine (DHβE) is a member of the Erythrina family of alkaloids and a potent competitive antagonist of the α4β2-subtype of the nicotinic acetylcholine receptors (nAChRs). Guided by an X-ray structure of DHβE in complex with an ACh binding protein, we detail the design, synthesis...

  3. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    Directory of Open Access Journals (Sweden)

    Mohammad eKhanfar

    2016-05-01

    Full Text Available With the very recent market approval of pitolisant (Wakix®, the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures.

  4. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists.

    Science.gov (United States)

    Khanfar, Mohammad A; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures.

  5. A pharmacophore model for dopamine D4 receptor antagonists

    Science.gov (United States)

    Boström, Jonas; Gundertofte, Klaus; Liljefors, Tommy

    2000-11-01

    A pharmacophore model for dopamine D4 antagonists has been developed on the basis of a previously reported dopamine D2 model. By using exhaustive conformational analyses (MM3* force field and the GB/SA hydration model) and least-squares molecular superimposition studies, a set of eighteen structurally diverse high affinity D4 antagonists have successfully been accommodated in the D4 pharmacophore model. Enantioselectivities may be rationalized by conformational energies required for the enantiomers to adopt their proposed bioactive conformations. The pharmacophore models for antagonists at the D4 and D2 receptor subtypes have been compared in order to get insight into molecular properties of importance for D2/D4 receptor selectivity. It is concluded that the bioactive conformations of antagonists at the two receptor subtypes are essentially identical. Receptor essential volumes previously identified for the D2 receptor are shown to be present also in the D4 receptor. In addition, a novel receptor essential volume in the D4 receptor, not present in the D2 receptor, has been identified. This feature may be exploited for the design of D4 selective antagonists. However, it is concluded that the major determinant for D2/D4 selectivity is the nature of the interactions between the receptor and aromatic ring systems. The effects of the electronic properties of these ring systems on the affinities for the two receptor subtypes differ substantially.

  6. Heterogeneity of binding of muscarinic receptor antagonists in rat brain homogenates

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.H.; el-Fakahany, E.E.

    1985-06-01

    The binding properties of (-)-(/sup 3/H)quinuclidinyl benzilate and (/sup 3/H) N-methylscopolamine to muscarinic acetylcholine receptors have been investigated in rat brain homogenates. The binding of both antagonists demonstrated high affinity and saturability. Analysis of the binding data resulted in linear Scatchard plots. However, (-)-(/sup 3/H)quinuclidinyl benzilate showed a significantly higher maximal binding capacity than that of (/sup 3/H)N-methylscopolamine. Displacement of both ligands with several muscarinic receptor antagonists resulted in competition curves in accordance with the law of mass-action for quinuclidinyl benzilate, atropine and scopolamine. A similar profile was found for the quaternary ammonium analogs of atropine and scopolamine when (/sup 3/H)N-methylscopolamine was used to label the receptors. However, when these hydrophilic antagonists were used to displace (-)-(/sup 3/H) quinuclidinyl benzilate binding, they showed interaction with high- and low-affinity binding sites. On the other hand, the nonclassical muscarinic receptor antagonist, pirenzepine, was able to displace both ligands from two binding sites. The present data are discussed in terms of the relationship of this anomalous heterogenity of binding of these hydrophilic muscarinic receptor antagonists and the proposed M1 and M2 receptor subtypes.

  7. New antagonist agents of neuropeptide y receptors

    Directory of Open Access Journals (Sweden)

    Ignacio Aldana

    2000-12-01

    Full Text Available In the CNS, NPY has been implicated in obesity and feeding, endocrine function and metabolism. Potent and selective rNPY antagonists will be able to probe the merits of this approach for the treatment of obesity. We report the synthesis and preliminary evaluation of some hydrazide derivatives as antagonists of rNPY.

  8. A SELECTIVE ANTAGONIST OF MINERALOCORTICOID RECEPTOR EPLERENONE IN CARDIOLOGY PRACTICE

    Directory of Open Access Journals (Sweden)

    B. B. Gegenava

    2015-09-01

    Full Text Available The role of aldosterone in pathophysiological processes is considered. The effects of the selective antagonist of mineralocorticoid receptor eplerenone are analyzed. The advantages of eplerenone compared with spironolactone are discussed.

  9. Tranylcypromine substituted cis-hydroxycyclobutylnaphthamides as potent and selective dopamine D₃ receptor antagonists.

    Science.gov (United States)

    Chen, Jianyong; Levant, Beth; Jiang, Cheng; Keck, Thomas M; Newman, Amy Hauck; Wang, Shaomeng

    2014-06-12

    We report a class of potent and selective dopamine D3 receptor antagonists based upon tranylcypromine. Although tranylcypromine has a low affinity for the rat D3 receptor (K(i) = 12.8 μM), our efforts have yielded (1R,2S)-11 (CJ-1882), which has K(i) values of 2.7 and 2.8 nM at the rat and human dopamine D3 receptors, respectively, and displays respective selectivities of >10000-fold and 223-fold over the rat and human D2 receptors. Evaluation in a β-arrestin functional assay showed that (1R,2S)-11 is a potent and competitive antagonist at the human D3 receptor.

  10. Characterization of PCS1055, a novel muscarinic M4 receptor antagonist.

    Science.gov (United States)

    Croy, Carrie H; Chan, Wai Y; Castetter, Andrea M; Watt, Marla L; Quets, Anne T; Felder, Christian C

    2016-07-05

    Identification of synthetic ligands selective for muscarinic receptor subtypes has been challenging due to the high sequence identity and structural homology among the five muscarinic acetylcholine receptors. Here, we report the pharmacological characterization of PCS1055, a novel muscarinic M4 receptor antagonist. PCS1055 inhibited radioligand [(3)H]-NMS binding to the M4 receptor with a Ki=6.5nM. Though the potency of PCS1055 is lower than that of pan-muscarinic antagonist atropine, it has better subtype selectivity over previously reported M4-selective reagents such as the muscarinic-peptide toxins (Karlsson et al., 1994; Santiago and Potter, 2001a) at the M1 subtype, and benzoxazine ligand PD102807 at the M3-subtype (Bohme et al., 2002). A detailed head-to-head comparison study using [(3)H]-NMS competitive binding assays characterizes the selectivity profiles of PCS1055 to that of other potent muscarinic-antagonist compounds PD102807, tropicamide, AF-DX-384, pirenzapine, and atropine. In addition to binding studies, the subtype specificity of PCS1055 is also demonstrated by functional receptor activation as readout by GTP-γ-[(35)S] binding. These GTP-γ-[(35)S] binding studies showed that PCS1055 exhibited 255-, 69.1-, 342- and >1000-fold greater inhibition of Oxo-M activity at the M4 versus the M1-, M2(-), M3-or M5 receptor subtypes, respectively. Schild analyses indicates that PCS1055 acts as a competitive antagonist to muscarinic M4 receptor, and confirms the affinity of the ligand to be low nanomolar, Kb=5.72nM. Therefore, PCS1055 represents a new M4-preferring antagonist that may be useful in elucidating the roles of M4 receptor signaling.

  11. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    OpenAIRE

    Mohammad eKhanfar; Anna eAffini; Kiril eLutsenko; Katarina eNikolic; Stefania eButini; Holger eStark

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex...

  12. Deficiency of interleukin-1 receptor antagonist responsive to anakinra.

    Science.gov (United States)

    Schnellbacher, Charlotte; Ciocca, Giovanna; Menendez, Roxanna; Aksentijevich, Ivona; Goldbach-Mansky, Raphaela; Duarte, Ana M; Rivas-Chacon, Rafael

    2013-01-01

    We describe a 3-month-old infant who presented to our institution with interleukin (IL)-1 receptor antagonist deficiency (DIRA), which consists of neutrophilic pustular dermatosis, periostitis, aseptic multifocal osteomyelitis, and persistently high acute-phase reactants. Skin findings promptly improved upon initiation of treatment with anakinra (recombinant human IL-1 receptor antagonist), and the bony lesions and systemic inflammation resolved with continued therapy.

  13. Histamine-2 receptor antagonists as immunomodulators: new therapeutic views?

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen

    1996-01-01

    from such studies are currently accumulating and suggest that the histamine-2 receptor antagonists have potential beneficial effects in the treatment of certain malignant, autoimmune and skin diseases, either alone or in combination with other drugs. The beneficial effect of histamine-2 receptor...... antagonists as adjuvant single drugs to reduce trauma-, blood transfusion- and sepsis-induced immunosuppression has led to research in combined treatment regimens in major surgery, particularly, of patients operated on for malignant diseases....

  14. Interleukin-2 receptor antagonists as induction therapy after heart transplantation

    DEFF Research Database (Denmark)

    Møller, Christian H; Gustafsson, Finn; Gluud, Christian;

    2008-01-01

    About half of the transplantation centers use induction therapy after heart transplantation. Interleukin-2 receptor antagonists (IL-2Ras) are used increasingly for induction therapy. We conducted a systematic review of randomized trials assessing IL-2Ras.......About half of the transplantation centers use induction therapy after heart transplantation. Interleukin-2 receptor antagonists (IL-2Ras) are used increasingly for induction therapy. We conducted a systematic review of randomized trials assessing IL-2Ras....

  15. Antagonists of the kappa opioid receptor.

    Science.gov (United States)

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  16. Identification of a novel conformationally constrained glucagon receptor antagonist.

    Science.gov (United States)

    Lee, Esther C Y; Tu, Meihua; Stevens, Benjamin D; Bian, Jianwei; Aspnes, Gary; Perreault, Christian; Sammons, Matthew F; Wright, Stephen W; Litchfield, John; Kalgutkar, Amit S; Sharma, Raman; Didiuk, Mary T; Ebner, David C; Filipski, Kevin J; Brown, Janice; Atkinson, Karen; Pfefferkorn, Jeffrey A; Guzman-Perez, Angel

    2014-02-01

    Identification of orally active, small molecule antagonists of the glucagon receptor represents a novel treatment paradigm for the management of type 2 diabetes mellitus. The present work discloses novel glucagon receptor antagonists, identified via conformational constraint of current existing literature antagonists. Optimization of lipophilic ligand efficiency (LLE or LipE) culminated in enantiomers (+)-trans-26 and (-)-trans-27 which exhibit good physicochemical and in vitro drug metabolism profiles. In vivo, significant pharmacokinetic differences were noted with the two enantiomers, which were primarily driven through differences in clearance rates. Enantioselective oxidation by cytochrome P450 was ruled out as a causative factor for pharmacokinetic differences.

  17. Approaches to the rational design of selective melanocortin receptor antagonists

    Science.gov (United States)

    Hruby, Victor J; Cai, Minying; Nyberg, Joel; Muthu, Dhanasekaran

    2015-01-01

    Introduction When establishing the physiological roles of specific receptors in normal and disease states, it is critical to have selective antagonist ligands for each receptor in a receptor system with several subtypes. The melanocortin receptors have five subtypes referred to as the melanocortin 1 receptor, melanocortin 2 receptor, melanocortin 3 receptor, melanocortin 4 receptor and melanocortin 5 receptor, and they are of critical importance for many aspects of human health and disease. Areas covered This article reviews the current efforts to design selective antagonistic ligands for the five human melanocortin receptors summarizing the currently published orthosteric and allosteric antagonists for each of these receptors. Expert opinion Though there has been progress, there are still few drugs available that address the many significant biological activities and diseases that are associated with these receptors, which is possibly due to the lack of receptor selectivity that these designed ligands are currently showing. The authors believe that further studies into the antagonists’ 3D conformational and topographical properties in addition to future mutagenesis studies will provide greater insight into these ligands which could play a role in the treatment of various diseases in the future. PMID:22646078

  18. Combining Elements from Two Antagonists of Formyl Peptide Receptor 2 Generates More Potent Peptidomimetic Antagonists.

    Science.gov (United States)

    Skovbakke, Sarah Line; Holdfeldt, André; Nielsen, Christina; Hansen, Anna Mette; Perez-Gassol, Iris; Dahlgren, Claes; Forsman, Huamei; Franzyk, Henrik

    2017-08-24

    Structural optimization of a peptidomimetic antagonist of formyl peptide receptor 2 (FPR2) was explored by an approach involving combination of elements from the two most potent FPR2 antagonists described: a Rhodamine B-conjugated 10-residue gelsonin-derived peptide (i.e., PBP10, RhB-QRLFQVKGRR-OH) and the palmitoylated α-peptide/β-peptoid hybrid Pam-(Lys-βNspe)6-NH2. This generated an array of hybrid compounds from which a new subclass of receptor-selective antagonists was identified. The most potent representatives displayed activity in the low nanomolar range. The resulting stable and potent FPR2-selective antagonists (i.e., RhB-(Lys-βNphe)n-NH2; n = 4-6) are expected to become valuable tools in further elucidation of the physiological role of FPR2 in health and disease.

  19. Kinetic properties of 'dual' orexin receptor antagonists at OX1R and OX2R orexin receptors.

    Directory of Open Access Journals (Sweden)

    Gabrielle Elizabeth Callander

    2013-12-01

    Full Text Available Orexin receptor antagonists represent attractive targets for the development of drugs for the treatment of insomnia. Both efficacy and safety are crucial in clinical settings and thorough investigations of pharmacokinetics and pharmacodynamics can predict contributing factors such as duration of action and undesirable effects. To this end, we studied the interactions between various ‘dual’ orexin receptor antagonists and the orexin receptors, OX1R and OX2R, over time using saturation and competition radioligand binding with [3H]-BBAC ((S-N-([1,1'-biphenyl]-2-yl-1-(2-((1-methyl-1H-benzo[d]imidazol-2-ylthioacetylpyrrolidine-2-carboxamide. In addition, the kinetics of these compounds were investigated in cells expressing human, mouse and rat OX1R and OX2R using FLIPR® assays for calcium accumulation. We demonstrate that almorexant reaches equilibrium very slowly at OX2R, whereas SB-649868, suvorexant and filorexant may take hours to reach steady state at both orexin receptors. By contrast, compounds such as BBAC or the selective OX2R antagonist IPSU ((2-((1H-Indol-3-ylmethyl-9-(4-methoxypyrimidin-2-yl-2,9-diazaspiro[5.5]undecan-1-one bind rapidly and reach equilibrium very quickly in both binding and / or functional assays. Overall, the dual antagonists tested here tend to be rather unselective under non-equilibrium conditions and reach equilibrium very slowly. Once equilibrium is reached, each ligand demonstrates a selectivity profile that is however, distinct from the non-equilibrium condition. The slow kinetics of the dual antagonists tested suggest that in vitro receptor occupancy may be longer lasting than would be predicted. This raises questions as to whether pharmacokinetic studies measuring plasma or brain levels of these antagonists are accurate reflections of receptor occupancy in vivo.

  20. Identification of three muscarinic receptor subtypes in rat lung using binding studies with selective antagonists

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, A.D.; El-Fakahany, E.E. (Univ. of Maryland, Baltimore (USA))

    1990-01-01

    Heterogeneity of the muscarinic receptor population in the rat central and peripheral lung was found in competition binding experiments against ({sup 3}H)quinuclidinyl benzilate (({sup 3}H)QNB) using the selective antagonists pirenzepine, AF-DX 116 and hexahydrosiladifenidol (HHSiD). Pirenzepine displaced ({sup 3}H)QNB with low affinity from preparations of central airways indicating the absence of M{sub 1} receptors in the trachea and bronchi. Muscarinic receptors in the central airways are comprised of both M{sub 2} and M{sub 3} receptors since AF-DX 116, an M{sub 2}-selective antagonist, bound with high affinity to 70% of the available sites while HHSiD, an M{sub 3}-selective antagonist bound with high affinity to the remaining binding sites. In the peripheral lung, pirenzepine bound with high affinity to 14% of the receptor population, AF-DX 116 bound with high affinity 79% of the binding sites while HHSiD bound with high affinity to 18% of the binding sites. The presence of M{sub 1} receptors in the peripheral airways but not in the central airways was confirmed using ({sup 3}H)telenzepine, an M{sub 1} receptor ligand. ({sup 3}H)Telenzepine showed specific saturable binding to 8% of ({sup 3}H)QNB labeled binding sites in homogenates of rat peripheral lung, while there was no detectable specific binding in homogenates of rat trachea or heart.

  1. Endothelin receptor antagonists influence cardiovascular morphology in uremic rats.

    Science.gov (United States)

    Nabokov, A V; Amann, K; Wessels, S; Münter, K; Wagner, J; Ritz, E

    1999-02-01

    In is generally held that renal failure results in blood pressure (BP)-independent structural changes of the myocardium and the vasculature. The contribution, if any, of endothelin (ET) to these changes has been unknown. We morphometrically studied random samples of the left ventricle myocardium and small intramyocardial arteries in subtotally (5/6) nephrectomized (SNx) male Sprague-Dawley rats treated with either the selective ETA receptor antagonist BMS182874 (30 mg/kg/day) or the nonselective ETA/ETB receptor antagonist Ro46-2005 (30 mg/kg/day) in comparison with either sham-operated rats, untreated SNx, or SNx rats treated with the angiotensin-converting enzyme inhibitor trandolapril (0.1 mg/kg/day). Eight weeks later, systolic BP was lower in trandolapril-treated SNx compared with untreated SNx animals. No decrease in BP was seen following either ET receptor antagonist at the dose used. A significantly increased volume density of the myocardial interstitium was found in untreated SNx rats as compared with sham-operated controls. Such interstitial expansion was prevented by trandolapril and either ET receptor antagonist. SNx caused a substantial increase in the wall thickness of small intramyocardial arteries. The increase was prevented by trandolapril or BMS182874 treatment. The arteriolar wall:lumen ratio was significantly lower in all treated groups when compared with untreated SNx. In contrast, only trandolapril, but not the ET receptor antagonists, attenuated thickening of the aortic media in SNx animals. The ETA-selective and ETA/ETB-nonselective receptor antagonists appear to prevent development of myocardial fibrosis and structural changes of small intramyocardial arteries in experimental chronic renal failure. This effect is independent of systemic BP.

  2. Serotonin 2A receptor antagonists for treatment of schizophrenia

    DEFF Research Database (Denmark)

    Ebdrup, Bjørn Hylsebeck; Rasmussen, Hans; Arnt, Jørn

    2011-01-01

    Introduction: All approved antipsychotic drugs share an affinity for the dopamine 2 (D2) receptor; however, these drugs only partially ameliorate the symptoms of schizophrenia. It is, therefore, of paramount importance to identify new treatment strategies for schizophrenia. Areas covered......: Preclinical, clinical and post-mortem studies of the serotonin 5-HT2A system in schizophrenia are reviewed. The implications of a combined D2 and 5-HT2A receptor blockade, which is obtained by several current antipsychotic drugs, are discussed, and the rationale for the development of more selective 5-HT2A...... receptor antagonists is evaluated. Moreover, the investigational pipeline of major pharmaceutical companies is examined and an Internet search conducted to identify other pharmaceutical companies investigating 5-HT2A receptor antagonists for the treatment of schizophrenia. Expert opinion: 5-HT2A receptor...

  3. Drug discovery and chemokine receptor antagonists: eppur si muove!

    Science.gov (United States)

    Terricabras, Emma; Benjamim, Claudia; Godessart, Nuria

    2004-11-01

    The blockade of leukocyte migration has been demonstrated to be a valid option for the treatment of several autoimmune diseases. Chemokines play an active role in regulating cell infiltration into inflammatory sites and disrupting chemokine-receptor interactions has emerged as an alternative therapeutic approach. Pharmaceutical companies have developed an intense activity in the drug discovery of chemokine receptor antagonists in the last 10 years. Potent and selective compounds have been obtained and some of them are currently being evaluated in the clinic. The success of these trials will demonstrate whether the blockade of a single receptor is of therapeutic benefit. Alternative approaches, such as pan-receptor antagonists or inhibitors of the signalling pathways evoked by chemokines, are also being explored. In the meantime, new relationships between chemokines and receptors will be revealed, increasing our knowledge of such a fascinating field.

  4. Enhanced Chronic Pain Management Utilizing Chemokine Receptor Antagonists

    Science.gov (United States)

    2016-08-01

    swelling and pain determined, along with initial experiments on the chemokine receptor antagonist (CRA) AMD3100. Methods were established for measuring a...Presentations………………………….22 7. Inventions , Patents and Licenses……………………..………….22 8. Reportable Outcomes……………………………………………….22 9. Other Achievements...Chemokines; Chemokine receptor antagonists; Opioid analgesics; Animal models of pain; Chemokine and cytokine measurements 3. OVERALL PROJECT

  5. Interleukin-1-receptor antagonist in type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Larsen, Claus M; Faulenbach, Mirjam; Vaag, Allan

    2007-01-01

    BACKGROUND: The expression of interleukin-1-receptor antagonist is reduced in pancreatic islets of patients with type 2 diabetes mellitus, and high glucose concentrations induce the production of interleukin-1beta in human pancreatic beta cells, leading to impaired insulin secretion, decreased cell...... proliferation, and apoptosis. METHODS: In this double-blind, parallel-group trial involving 70 patients with type 2 diabetes, we randomly assigned 34 patients to receive 100 mg of anakinra (a recombinant human interleukin-1-receptor antagonist) subcutaneously once daily for 13 weeks and 36 patients to receive...

  6. Pharmacological significance of the interplay between angiotensin receptors: MAS receptors as putative final mediators of the effects elicited by angiotensin AT1 receptors antagonists.

    Science.gov (United States)

    Pernomian, Larissa; Pernomian, Laena; Gomes, Mayara S; da Silva, Carlos H T P

    2015-12-15

    The interplay between angiotensin AT1 receptors and MAS receptors relies on several inward regulatory mechanisms from renin-angiotensin system (RAS) including the functional crosstalk between angiotensin II and angiotensin-(1-7), the competitive AT1 antagonism exhibited by angiotensin-(1-7), the antagonist feature assigned to AT1/MAS heterodimerization on AT1 signaling and the AT1-mediated downregulation of angiotensin-converting enzyme 2 (ACE2). Recently, such interplay has acquired an important significance to RAS Pharmacology since a few studies have supporting strong evidences that MAS receptors mediate the effects elicited by AT1 antagonists. The present Perspective provides an overview of the regulatory mechanisms involving AT1 and MAS receptors, their significance to RAS Pharmacology and the future directions on the interplay between angiotensin receptors. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. X-ray structures define human P2X3 receptor gating cycle and antagonist action

    Science.gov (United States)

    Mansoor, Steven E.; Lü, Wei; Oosterheert, Wout; Shekhar, Mrinal; Tajkhorshid, Emad; Gouaux, Eric

    2016-10-01

    P2X receptors are trimeric, non-selective cation channels activated by ATP that have important roles in the cardiovascular, neuronal and immune systems. Despite their central function in human physiology and although they are potential targets of therapeutic agents, there are no structures of human P2X receptors. The mechanisms of receptor desensitization and ion permeation, principles of antagonism, and complete structures of the pore-forming transmembrane domains of these receptors remain unclear. Here we report X-ray crystal structures of the human P2X3 receptor in apo/resting, agonist-bound/open-pore, agonist-bound/closed-pore/desensitized and antagonist-bound/closed states. The open state structure harbours an intracellular motif we term the ‘cytoplasmic cap’, which stabilizes the open state of the ion channel pore and creates lateral, phospholipid-lined cytoplasmic fenestrations for water and ion egress. The competitive antagonists TNP-ATP and A-317491 stabilize the apo/resting state and reveal the interactions responsible for competitive inhibition. These structures illuminate the conformational rearrangements that underlie P2X receptor gating and provide a foundation for the development of new pharmacological agents.

  8. Intracerebroventricular application of competitive and non-competitive NMDA antagonists induce similar effects upon rat hippocampal electroencephalogram and local cerebral glucose utilization

    NARCIS (Netherlands)

    Boddeke, H.W.G.M.; Wiederhold, K.H.; Palacios, J.M.

    1992-01-01

    In this study we have used electrophysiological and metabolic markers to investigate the effects of competitive and non-competitive NMDA antagonists in rats after central or peripheral administration. The non-competitive antagonist, MK-801, induced dose-dependent suppression of rat hippocampal EEG e

  9. Receptor discrimination and control of agonist-antagonist binding.

    Science.gov (United States)

    Tallarida, R J

    1995-08-01

    The law of mass action is the common model for the interaction of agonist and antagonist compounds with cellular receptors. Parameters of the interaction, obtained from functional and radioligand-binding studies, allow discrimination and subtyping of receptors and aid in understanding specific mechanisms. This article reviews the theory and associated mathematical models and graphical transformations of data that underlie the determination of receptor parameters. The main theory assumes that agonist and antagonist compounds bind to cells that have a fixed number of receptors and provides the framework for obtaining drug-receptor parameters from data and their graphical transformations. Conditions that produce a change in receptor number, a newer concept in pharmacology, can have an important effect on the parameter values derived in the usual way. This review concludes with a discussion of the quantitative study of receptor-mediated feedback control of endogenous ligands, a very new topic with potentially important implications for understanding antagonist effectiveness, loss of control, and chaos in regulated mass action binding.

  10. 竞争性α-氨基-3-羟基-5-甲基-4-异唑恶唑丙酸受体拮抗剂研究进展%Competitiveα-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid receptor antagonists:research advances

    Institute of Scientific and Technical Information of China (English)

    肖典; 王凌霄; 周辛波; 李松

    2014-01-01

    α-氨基-3-羟基-5-甲基-4-异唑恶唑丙酸(AMPA)受体是游离型谷氨酸受体,广泛分布于中枢神经系统,介导快速兴奋性突触传递。越来越多的证据表明,其在突触可塑性及中枢敏化中发挥重要作用,并且与神经系统疾病关系密切。过度刺激AMPA受体产生兴奋性毒性会导致神经元损伤,引发癫痫、肌萎缩侧索硬化和帕金森病等一系列神经系统疾病的发生。竞争性AMPA受体拮抗剂能够有效下调AMPA受体活性,对预防和治疗神经系统疾病意义重大。本文对竞争性AMPA受体拮抗剂的研究进展进行综述。%α-Amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) receptor, a subtype of ionotropic glutamate receptors widely distributed in the central nervous system, mediates the fast excitatory neurotransmission. Meanwhile more and more evidence indicates that AMPA receptor plays an important role in synaptic plasticity as well as central sensitization, and it also has close relationships with nervous system diseases. Over stimulation of AMPA receptor would produce excitotoxicity, leading to neuronal damage and finally resulting in a multitude of nervous system diseases, such as epilepsy, amyotrophic lateral scelerosis,Parkinson′s dis-ease. Competitive AMPA receptor antagonists that downregulate AMPA receptor′s function are of great importance in the prevention and treatment of nervous system diseases. This article reviews the research advances of competitive AMPA receptor antagonists.

  11. Bronchoprotection with a leukotriene receptor antagonist in asthmatic preschool children

    DEFF Research Database (Denmark)

    Bisgaard, H; Nielsen, K G

    2000-01-01

    We hypothesized that a leukotriene receptor antagonist (LTRA) could provide bronchoprotection against the cold, dry air-induced response in asthmatic preschool children. In a randomized, double-blind, placebo-controlled crossover study, we examined the effect of the specific LTRA montelukast at 5...

  12. Kappa opioid receptor antagonist and N-methyl-D- aspartate receptor antagonist affect dynorphin- induced spinal cord electrophysiologic impairment

    Institute of Scientific and Technical Information of China (English)

    Yu Chen; Liangbi Xiang; Jun Liu; Dapeng Zhou; Hailong Yu; Qi Wang; Wenfeng Han; Weijian Ren

    2012-01-01

    The latencies of motor- and somatosensory-evoked potentials were prolonged to different degrees, and wave amplitude was obviously decreased, after injection of dynorphin into the rat subarachnoid cavity.The wave amplitude and latencies of motor- and somatosensory-evoked potentials were significantly recovered at 7 and 14 days after combined injection of dynorphin and either the kappa opioid receptor antagonist nor-binaltorphimine or the N-methyl-D-aspartate receptor antagonist MK-801.The wave amplitude and latency were similar in rats after combined injection of dynorphin and nor-binaltorphimine or MK-801.These results suggest that intrathecal injection of dynorphin causes damage to spinal cord function.Prevention of N-methyl-D-aspartate receptor or kappa receptor activation lessened the injury to spinal cord function induced by dynorphin.

  13. Aldosterone receptor antagonists: current perspectives and therapies

    OpenAIRE

    Guichard JL; Clark III D; Calhoun DA; Ahmed MI

    2013-01-01

    Jason L Guichard, Donald Clark III, David A Calhoun, Mustafa I Ahmed University of Alabama at Birmingham, Department of Medicine, Division of Cardiovascular Disease, Vascular Biology and Hypertension Program, Birmingham, AL, USA Abstract: Aldosterone is a downstream effector of angiotensin II in the renin–angiotensin–aldosterone system and binds to the mineralocorticoid receptor. The classical view of aldosterone primarily acting at the level of the kidneys to regulate pl...

  14. Preclinical anxiolytic profiles of 7189 and 8319, novel non-competitive NMDA antagonists

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, R.W.; Corbett, R.; Martin, L.L.; Payack, J.F.; Laws-Ricker, L.; Wilmot, C.A.; Rush, D.K.; Cornfeldt, M.L.; Fielding, S. (Hoechst-Roussel Pharmaceuticals, Inc. Somerville, NJ (USA))

    1990-01-01

    Antagonists at excitatory amino acid receptors, especially the N-methyl-d-aspartate (NMDA) subtype, have been shown to possess anticonvulsant and anxiolytic properties. Two closely related benzeneethanamines, are potential novel anxiolytic agents which bind with high affinity to the NMDA receptor at the non-competitive site and are relatively non-toxic (LD50's-160 mg/kg, ip). 7189 and 8319 showed anxiolytic effects in schedule controlled conflict assays as well as in the social interaction (SI) and elevated plus maze (EPM) procedures in rats. Following intraperitoneal administration of 7189 at 20 to 60 mg/kg, conflict responding was increased from 2- to 7-fold in the modified Cook and Davidson and Geller conflict paradigms. 8319, at 2.5 to 5 mg/kg, produced a two fold increase in conflict responding. In the non-schedule controlled procedures, 7189 at 20 mg/kg increased SI time by 23% while in the EPM at 10 to 20 mg/kg, open arm exploration time increased by 41 to 77%. Likewise, 8319 at 2.5 and 5 mg/kg increased open arm exploration and SI time by 50 and 37%, respectively. In summary, 7189 and 8319 were efficacious in four behavioral procedures predictive of potential anxiolytic agents. Although these compounds have not been submitted for clinical evaluation, they may represent a new class of beneficial compounds for the treatment of anxiety.

  15. Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist

    Science.gov (United States)

    Johnson, David G.; Ulichny Goebel, Camy; Hruby, Victor J.; Bregman, Marvin D.; Trivedi, Dev

    1982-02-01

    The glucagon analog [l-Nα-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.

  16. Pharmacology of JB-9315, a new selective histamine H2-receptor antagonist.

    Science.gov (United States)

    Palacios, B; Montero, M J; Sevilla, M A; San Román, L

    1998-02-01

    1. The histamine H2-receptor antagonistic activity and antisecretory and antiulcer effects of JB-9315 were studied in comparison with the standard H2 blocker ranitidine. 2. In vitro, JB-9315 is a competitive antagonist of histamine H2 receptors in the isolated, spontaneously beating guinea-pig right atrium, with a pA2 value of 7.30 relative to a value of 7.36 for ranitidine. JB-9315 was specific for the histamine H2 receptor because, at high concentration, it did not affect histamine- or acetylcholine-induced contractions in guinea-pig isolated ileum or rat isolated duodenum, respectively. 3. JB-9315 dose dependently inhibited histamine-, pentagastrin- or carbachol-stimulated acid secretion and basal secretion in the perfused stomach preparation of the anesthetized rat. In the pylorus-ligated rat after intraperitoneal administration, total acid output over 4 h was inhibited by JB-9315 with an ID50 of 32.8 mg/kg, confirming its H2-receptor antagonist properties. 4. JB-9315 showed antiulcer activity against cold stress plus indomethacin-induced lesions with an ID50 of 6.8 mg/kg. 5. JB-9315, 50 and 100 mg/kg, inhibited macroscopic gastric hemorrhagic lesions induced by ethanol. In contrast, ranitidine (50 mg/kg) failed to reduce these lesions. 6. These results indicate that JB-9315 is a new antiulcer drug that exerts a cytoprotective effect in addition to its gastric antisecretory activity.

  17. Recombinant human interleukin-1 receptor antagonist in severe traumatic brain injury: a phase II randomized control trial

    OpenAIRE

    Helmy, Adel; Guilfoyle, Mathew R.; Carpenter, Keri LH; Pickard, John D.; Menon, David K.; Hutchinson, Peter J.

    2014-01-01

    Traumatic brain injury (TBI) is the commonest cause of death and disability in those aged under 40 years. Interleukin-1 receptor antagonist (IL1ra) is an endogenous competitive antagonist at the interleukin-1 type-1 receptor (IL-1R). Antagonism at the IL-1R confers neuroprotection in several rodent models of neuronal injury (i.e., trauma, stroke and excitotoxicity). We describe a single center, phase II, open label, randomized-control study of recombinant human IL1ra (rhIL1ra, anakinra) in se...

  18. Halogenation of a capsaicin analogue leads to novel vanilloid TRPV1 receptor antagonists

    Science.gov (United States)

    Appendino, Giovanni; Harrison, Selena; De Petrocellis, Luciano; Daddario, Nives; Bianchi, Federica; Schiano Moriello, Aniello; Trevisani, Marcello; Benvenuti, Francesca; Geppetti, Pierangelo; Di Marzo, Vincenzo

    2003-01-01

    The C-5 halogenation of the vanillyl moiety of resiniferatoxin, an ultrapotent agonist of vanilloid TRPV1 receptors, results in a potent antagonist for these receptors. Here, we have synthesized a series of halogenated derivatives of ‘synthetic capsaicin' (nonanoyl vanillamide=nordihydrocapsaicin) differing for the nature (iodine, bromine–chlorine) and the regiochemistry (C-5, C-6) of the halogenation.The activity of these compounds was investigated on recombinant human TRPV1 receptors overexpressed in HEK-293 cells. None of the six compounds exerted any significant agonist activity, as assessed by measuring their effect on TRPV1-mediated calcium mobilization. Instead, all compounds antagonized, to various extents, the effect of capsaicin in this assay.All 6-halo-nordihydrocapsaicins behaved as competitive antagonists against human TRPV1 according to the corresponding Schild's plots, and were more potent than the corresponding 5-halogenated analogues. The iodo-derivatives were more potent than the bromo- and chloro-derivatives.Using human recombinant TRPV1, 6-iodo-nordihydrocapsaicin (IC50=10 nM against 100 nM capsaicin) was about four times more potent than the prototypical TRPV1 antagonist, capsazepine, and was tested against capsaicin also on native TRPV1 in: (i) rat dorsal root ganglion neurons in culture; (ii) guinea-pig urinary bladder; and (iii) guinea-pig bronchi. In all cases, except for the guinea-pig bronchi, the compound was significantly more potent than capsazepine as a TRPV1 antagonist.In conclusion, 6-iodo-nordihydrocapsaicin, a stable and easily prepared compound, is a potent TRPV1 antagonist and a convenient replacement for capsazepine in most of the in vitro preparations currently used to assess the activity of putative vanilloid receptor agonists. PMID:12922928

  19. μ Opioid receptor: novel antagonists and structural modeling

    Science.gov (United States)

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-02-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

  20. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    Science.gov (United States)

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.

  1. A long-acting GH receptor antagonist through fusion to GH binding protein.

    Science.gov (United States)

    Wilkinson, Ian R; Pradhananga, Sarbendra L; Speak, Rowena; Artymiuk, Peter J; Sayers, Jon R; Ross, Richard J

    2016-10-12

    Acromegaly is a human disease of growth hormone (GH) excess with considerable morbidity and increased mortality. Somatostatin analogues are first line medical treatment but the disease remains uncontrolled in up to 40% of patients. GH receptor (GHR) antagonist therapy is more effective but requires frequent high-dose injections. We have developed an alternative technology for generating a long acting potent GHR antagonist through translational fusion of a mutated GH linked to GH binding protein and tested three candidate molecules. All molecules had the amino acid change (G120R), creating a competitive GHR antagonist and we tested the hypothesis that an amino acid change in the GH binding domain (W104A) would increase biological activity. All were antagonists in bioassays. In rats all antagonists had terminal half-lives >20 hours. After subcutaneous administration in rabbits one variant displayed a terminal half-life of 40.5 hours. A single subcutaneous injection of the same variant in rabbits resulted in a 14% fall in IGF-I over 7 days.

  2. Churg-Strauss syndrome associated with leukotriene receptor antagonists (LTRA).

    Science.gov (United States)

    Cuchacovich, R; Justiniano, M; Espinoza, L R

    2007-10-01

    Churg-Strauss syndrome (CSS) is a rare vasculitic disorder that generally occurs in patients with bronchial asthma. CSS is being increasingly recognized in asthmatic patients treated with leukotriene receptor antagonists. However, the nature of this relationship remains to be elucidated. The present report describes three asthmatic patients who developed clinical manifestations highly suggestive of CSS, although one patient lacked the presence of eosinophilia. The patient, however, exhibited biopsy-proven cutaneous necrotizing vasculitis, which improved after withdrawal of montelukast. The second patient presented with systemic constitutional signs including fever, malaise, arthralgias, clinical jaundice, peripheral blood eosinophilia, and biopsy-proven eosinophilic hepatitis. The third patient also had circulating eosinophilia, scleritis, and arthritis. All patients improved after discontinuation of the leukotriene receptor antagonist (montelukast).

  3. Mineralocorticoid receptor antagonists: emerging roles in cardiovascular medicine

    OpenAIRE

    Funder JW

    2013-01-01

    John W FunderPrince Henry's Institute, Clayton, Victoria, AustraliaAbstract: Spironolactone was first developed over 50 years ago as a potent mineralocorticoid receptor (MR) antagonist with undesirable side effects; it was followed a decade ago by eplerenone, which is less potent but much more MR-specific. From a marginal role as a potassium-sparing diuretic, spironolactone was shown to be an extraordinarily effective adjunctive agent in the treatment of progressive heart failure, as ...

  4. Discovery of dopamine D₄ receptor antagonists with planar chirality.

    Science.gov (United States)

    Sanna, Fabrizio; Ortner, Birgit; Hübner, Harald; Löber, Stefan; Tschammer, Nuska; Gmeiner, Peter

    2013-04-01

    Employing the D4 selective phenylpiperazine 2 as a lead compound, planar chiral analogs with paracyclophane substructure were synthesized and evaluated for their ability to bind and activate dopamine receptors. The study revealed that the introduction of a [2.2]paracyclophane moiety is tolerated by dopamine receptors of the D2 family. Subtype selectivity for D4 and ligand efficacy depend on the absolute configuration of the test compounds. Whereas the achiral single-layered lead 2 and the double-layered paracyclophane (R)-3 showed partial agonist properties, the enantiomer (S)-3 behaved as a neutral antagonist.

  5. Estrogen Receptor Agonists and Antagonists in the Yeast Estrogen Bioassay.

    Science.gov (United States)

    Wang, Si; Bovee, Toine F H

    2016-01-01

    Cell-based bioassays can be used to predict the eventual biological activity of a substance on a living organism. In vitro reporter gene bioassays are based on recombinant vertebrate cell lines or yeast strains and especially the latter are easy-to-handle, cheap, and fast. Moreover, yeast cells do not express estrogen, androgen, progesterone or glucocorticoid receptors, and are thus powerful tools in the development of specific reporter gene systems that are devoid of crosstalk from other hormone pathways. This chapter describes our experience with an in-house developed RIKILT yeast estrogen bioassay for testing estrogen receptor agonists and antagonists, focusing on the applicability of the latter.

  6. Conidial persistence and competitive ability of the antagonist Ulocladium atrum on strawberry leaves.

    NARCIS (Netherlands)

    Boff, P.; Kraker, de J.; Bruggen, van A.H.C.; Gerlagh, M.; Köhl, J.

    2001-01-01

    The persistence of conidia and competitive ability of Ulocladium atrum, an antagonist of Botrytis cinerea, were studied in field plots of strawberry in The Netherlands. Single application of conidial suspensions (2 ± 106 conidia ml-1) of U. atrum were sprayed on the canopy and repeated 14 times, eac

  7. Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues

    Energy Technology Data Exchange (ETDEWEB)

    Waser, Beatrice; Reubi, Jean Claude [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, PO Box 62, Berne (Switzerland)

    2014-06-15

    Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the {sup 125}iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer {sup 125}I-GLP-1(7-36)amide. Receptor autoradiography studies with {sup 125}I-GLP-1(7-36)amide agonist or {sup 125}I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. The antagonist {sup 125}I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer {sup 125}I-GLP-1(7-36)amide. For comparison, {sup 125}I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. The GLP-1 receptor antagonist exendin(9-39) labelled with {sup 125}I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients. (orig.)

  8. Synthesis of 4-Amino-5-furyl-2-yl-4H-1,2,4-triazole-3-thiol Derivatives as a Novel Class of Endothelin(ET) Receptor Antagonists

    Institute of Scientific and Technical Information of China (English)

    Xin Yong LIU; Wen Fang XU; Jing De WU

    2003-01-01

    A series of novel 3-alkylthio-4-arylideneamino-5-(2-furyl)-1, 2, 4-triazole derivatives were synthesized. Their chemical structures were confirmed with elemental analysis and spectral data. Endothelin(ET) receptor competitive binding assay showed that some compounds exhibited high selective as potent ET-1 receptor antagonist.

  9. NMDA receptor antagonists extend the sensitive period for imprinting.

    Science.gov (United States)

    Parsons, C H; Rogers, L J

    2000-03-01

    Filial imprinting in the domestic chick occurs during a sensitive period of development. The exact timing of this period can vary according to the methods used to measure imprinting. Using our imprinting paradigm, we have shown that normal, dark-reared chicks lose the ability to imprint after the second day post-hatching. Further, we reported that chicks treated 10 h after hatching with a mixture of the noncompetitive NMDA receptor antagonist ketamine (55 mg/kg) and the alpha(2)-adrenergic receptor agonist xylazine (6 mg/kg) were able to imprint on day 8 after hatching, whereas controls treated with saline did not imprint. We now show that the effect of the ketamine-xylazine mixture can be mimicked by treating chicks with ketamine alone or with another noncompetitive NMDA receptor antagonist, MK-801 (5 mg/kg). Treating chicks with a single dose of ketamine (55 mg/kg) or with a single dose of xylazine (6 mg/kg) failed to produce the effect on the sensitive period. However, prolonging the action of ketamine by treating chicks with two doses of ketamine (at 10 and 12 h after hatching) did allow imprinting on day 8. In contrast, prolonging the action of xylazine had no effect on the sensitive period for imprinting. Chicks treated with MK-801 were also able to imprint on day 8. Thus, we have evidence that the NMDA receptor system is involved in the mechanisms that control the sensitive period for imprinting.

  10. CGRP receptor antagonists and antibodies against CGRP and its receptor in migraine treatment

    DEFF Research Database (Denmark)

    Edvinsson, Lars

    2015-01-01

    Recently developed calcitonin gene-related peptide (CGRP) receptor antagonistic molecules have shown promising results in clinical trials for acute treatment of migraine attacks. Drugs from the gepant class of CGRP receptor antagonists are effective and do not cause vasoconstriction, one...... for treatment of chronic migraine (attacks >15 days/month). Initial results from phase I and II clinical trials have revealed promising results with minimal side effects and significant relief from chronic migraine as compared with placebo. The effectiveness of these various molecules raises the question...... to understand the localization of CGRP and the CGRP receptor components in these possible sites of migraine-related regions and their relation to the BBB....

  11. Suvorexant: The first orexin receptor antagonist to treat insomnia

    Directory of Open Access Journals (Sweden)

    Ashok K Dubey

    2015-01-01

    Full Text Available Primary insomnia is mainly treated with drugs acting on benzodiazepine receptors and a few other classes of drugs used for different co-morbidities. A novel approach to treat insomnia has been introduced recently, with the approval of suvorexant, the first in a new class of orexin receptor antagonists. Orexin receptors in the brain have been found to play an important role in the regulation of various aspects of arousal and motivation. The drugs commonly used for insomnia therapy to date, have often been associated with adverse effects, such as, day-time somnolence, amnesia, confusion, and gait disturbance, apart from the risk of dependence on chronic use. Suvorexant has not shown these adverse effects because of its unique mechanism of action. It also appears to be suitable as a chronic therapy for insomnia, because of minimal physical dependence. The availability of this new drug as an effective and safe alternative is an important and welcome development in insomnia management.

  12. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    Science.gov (United States)

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  13. Potential Clinical Implications of the Urotensin II Receptor Antagonists

    Directory of Open Access Journals (Sweden)

    Emilie Kane

    2011-07-01

    Full Text Available Urotensin-II (UII, which binds to its receptor UT, plays an important role in the heart, kidneys, pancreas, adrenal gland and CNS. In the vasculature, it acts as a potent endothelium-independent vasoconstrictor and endothelium-dependent vasodilator. In disease states, this constriction-dilation equilibrium is disrupted. There is an upregulation of the UII system in heart disease, metabolic syndrome and kidney failure. The increase in UII release and UT expression suggest that UII system may be implicated in the pathology and pathogenesis of these diseases by causing an increase in ACAT-1 activity leading to SMC proliferation and foam cell infiltration, insulin resistance (DMII, as well as inflammation, high blood pressure and plaque formation. Recently, UT antagonists such as SB-611812, palosuran, and most recently a piperazino-isoindolinone based antagonist have been developed in the hope of better understanding the UII system and treating its associated diseases.

  14. Structure of CC chemokine receptor 2 with orthosteric and allosteric antagonists

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yi; Qin, Ling; Ortiz Zacarías, Natalia V.; de Vries, Henk; Han, Gye Won; Gustavsson, Martin; Dabros, Marta; Zhao, Chunxia; Cherney, Robert J.; Carter, Percy; Stamos, Dean; Abagyan, Ruben; Cherezov, Vadim; Stevens, Raymond C.; IJzerman, Adriaan P.; Heitman, Laura H.; Tebben, Andrew; Kufareva, Irina; Handel , Tracy M. (Vertex Pharm); (Leiden-MC); (USC); (BMS); (UCSD)

    2016-12-07

    CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human class A G-protein-coupled receptors. CCR2 is expressed on monocytes, immature dendritic cells, and T-cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL2 (ref. 1). CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases2 including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer3. These disease associations have motivated numerous preclinical studies and clinical trials4 (see http://www.clinicaltrials.gov) in search of therapies that target the CCR2–chemokine axis. To aid drug discovery efforts5, here we solve a structure of CCR2 in a ternary complex with an orthosteric (BMS-681 (ref. 6)) and allosteric (CCR2-RA-[R]7) antagonist. BMS-681 inhibits chemokine binding by occupying the orthosteric pocket of the receptor in a previously unseen binding mode. CCR2-RA-[R] binds in a novel, highly druggable pocket that is the most intracellular allosteric site observed in class A G-protein-coupled receptors so far; this site spatially overlaps the G-protein-binding site in homologous receptors. CCR2-RA-[R] inhibits CCR2 non-competitively by blocking activation-associated conformational changes and formation of the G-protein-binding interface. The conformational signature of the conserved microswitch residues observed in double-antagonist-bound CCR2 resembles the most inactive G-protein-coupled receptor structures solved so far. Like other protein–protein interactions, receptor–chemokine complexes are considered challenging therapeutic targets for small molecules, and the present structure suggests diverse pocket epitopes that can be exploited to overcome obstacles in drug design.

  15. Expression of metabotropic glutamate receptor 1a in a rat cortical neuronal model of in vitro mechanical injury and the effects of its competitive antagonist (RS)-1-aminoindan-1, 5-dicarboxylic acid

    Institute of Scientific and Technical Information of China (English)

    Fei Cao; Mantao Chen; Xiujue Zheng; Gu Li; Liang Wen; Xiaofeng Yang

    2011-01-01

    The present study established a rat cortical neuronal model of in vitro mechanical injury. At 30 min-utes after injury, the survival rate of the injured cortical neurons was decreased compared with normal neurons, and was gradually decreased with aggravated degree of injury. Reverse transcrip-tion-polymerase chain reaction results showed that at 1 hour after injury, there was increased ex-pression of metabotropic glutamate receptor 1a in cortical neurons. Immunohistochemical staining results showed that at 30 minutes after injury, the number of metabotropic glutamate receptor 1a-positive cells increased compared with normal neurons. At 12 hours after injury, lactate dehy-drogenase activity in the (RS)-1-aminoindan-1, 5-dicarboxylic acid (AIDA)-treated injury neurons was significantly decreased than that in the pure injury group. At 1 hour after injury, intracellular free Ca2+ concentration was markedly decreased in the AIDA-treated injury neurons than that in the pure injury neurons. These findings suggest that after mechanical injury to cortical neurons, metabotropic glutamate receptor 1a expression increased. The resulting increase in intracellular free Ca2+ con-centration was blocked by AIDA, indicating that AIDA exhibits neuroprotective effects after me-chanical injury.

  16. Effects of NMDA receptor antagonists on probability discounting depend on the order of probability presentation.

    Science.gov (United States)

    Yates, Justin R; Breitenstein, Kerry A; Gunkel, Benjamin T; Hughes, Mallory N; Johnson, Anthony B; Rogers, Katherine K; Shape, Sara M

    Risky decision making can be measured using a probability-discounting procedure, in which animals choose between a small, certain reinforcer and a large, uncertain reinforcer. Recent evidence has identified glutamate as a mediator of risky decision making, as blocking the N-methyl-d-aspartate (NMDA) receptor with MK-801 increases preference for a large, uncertain reinforcer. Because the order in which probabilities associated with the large reinforcer can modulate the effects of drugs on choice, the current study determined if NMDA receptor ligands alter probability discounting using ascending and descending schedules. Sixteen rats were trained in a probability-discounting procedure in which the odds against obtaining the large reinforcer increased (n=8) or decreased (n=8) across blocks of trials. Following behavioral training, rats received treatments of the NMDA receptor ligands MK-801 (uncompetitive antagonist; 0, 0.003, 0.01, or 0.03mg/kg), ketamine (uncompetitive antagonist; 0, 1.0, 5.0, or 10.0mg/kg), and ifenprodil (NR2B-selective non-competitive antagonist; 0, 1.0, 3.0, or 10.0mg/kg). Results showed discounting was steeper (indicating increased risk aversion) for rats on an ascending schedule relative to rats on the descending schedule. Furthermore, the effects of MK-801, ketamine, and ifenprodil on discounting were dependent on the schedule used. Specifically, the highest dose of each drug decreased risk taking in rats in the descending schedule, but only MK-801 (0.03mg/kg) increased risk taking in rats on an ascending schedule. These results show that probability presentation order modulates the effects of NMDA receptor ligands on risky decision making. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Evodiamine as a novel antagonist of aryl hydrocarbon receptor

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hui [State Key Laboratory of Trauma, Burns, and Combined Injury, Department 1, Research Institute of Surgery, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China); Department of Laboratory Medicine, The Affiliated Tenth People' s Hospital, Tongji University, Shanghai 200072 (China); Tu, Yongjiu; Zhang, Chun; Fan, Xia; Wang, Xi [State Key Laboratory of Trauma, Burns, and Combined Injury, Department 1, Research Institute of Surgery, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China); Wang, Zhanli [College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014 (China); Liang, Huaping, E-mail: huaping_liang@yahoo.com.cn [State Key Laboratory of Trauma, Burns, and Combined Injury, Department 1, Research Institute of Surgery, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China)

    2010-11-05

    Research highlights: {yields} Evodiamine interacted with the AhR. {yields} Evodiamine inhibited the specific binding of [{sup 3}H]-TCDD to the AhR. {yields} Evodiamine acts as an antagonist of the AhR. -- Abstract: Evodiamine, the major bioactive alkaloid isolated from Wu-Chu-Yu, has been shown to interact with a wide variety of proteins and modify their expression and activities. In this study, we investigated the interaction between evodiamine and the aryl hydrocarbon receptor (AhR). Molecular modeling results revealed that evodiamine directly interacted with the AhR. Cytosolic receptor binding assay also provided the evidence that evodiamine could interact with the AhR with the K{sub i} value of 28.4 {+-} 4.9 nM. In addition, we observed that evodiamine suppressed the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced nuclear translocation of the AhR and the expression of CYP1A1 dose-dependently. These results suggested that evodiamine was able to bind to the AhR as ligand and exhibit antagonistic effects.

  18. Classification and virtual screening of androgen receptor antagonists.

    Science.gov (United States)

    Li, Jiazhong; Gramatica, Paola

    2010-05-24

    Computational tools, such as quantitative structure-activity relationship (QSAR), are highly useful as screening support for prioritization of substances of very high concern (SVHC). From the practical point of view, QSAR models should be effective to pick out more active rather than inactive compounds, expressed as sensitivity in classification works. This research investigates the classification of a big data set of endocrine-disrupting chemicals (EDCs)-androgen receptor (AR) antagonists, mainly aiming to improve the external sensitivity and to screen for potential AR binders. The kNN, lazy IB1, and ADTree methods and the consensus approach were used to build different models, which improve the sensitivity on external chemicals from 57.1% (literature) to 76.4%. Additionally, the models' predictive abilities were further validated on a blind collected data set (sensitivity: 85.7%). Then the proposed classifiers were used: (i) to distinguish a set of AR binders into antagonists and agonists; (ii) to screen a combined estrogen receptor binder database to find out possible chemicals that can bind to both AR and ER; and (iii) to virtually screen our in-house environmental chemical database. The in silico screening results suggest: (i) that some compounds can affect the normal endocrine system through a complex mechanism binding both to ER and AR; (ii) new EDCs, which are nonER binders, but can in silico bind to AR, are recognized; and (iii) about 20% of compounds in a big data set of environmental chemicals are predicted as new AR antagonists. The priority should be given to them to experimentally test the binding activities with AR.

  19. Molecular Probes for Muscarinic Receptors: Derivatives of the M1-Antagonist Telenzepine

    Science.gov (United States)

    Karton, Yishai; Baumgold, Jesse; Handen, Jeffrey S.; Jacobson, Kenneth A.

    2012-01-01

    Functionalized congeners of the M1-selective muscarinic antagonist telenzepine (4,9-dihydro-3-methyl-4-[(4-methyl-1-piperazinyl)acetyl]-10H-thieno[3,4–b][1,5]benzodiazepin-10-one) were developed and found to bind to the receptor with affinities (Ki values) in approximately the nanomolar range. The derivatives contain a 10-aminodecyl group, which provides a nucleophilic functionality for further derivatization. The attachment of a spacer chain to the distal piperazinyl nitrogen was based on previous findings of enhanced affinity at muscarinic receptors in an analogous series of alkylamino derivatives of pirenzepine [J. Med. Chem. (1991) 34, 2133–2145]. The telenzepine derivatives contain prosthetic groups for radioiodination, protein cross-linking, photoaffinity labeling, and fluorescent labeling and biotin for avidin complexation. The affinity for muscarinic receptors in rat forebrain (mainly m1 subtype) was determined in competitive binding assays vs [3H]-N-methylscopolamine. A (p-aminophenyl)-acetyl derivative for photoaffinity labeling had a Ki value of 0.29 nM at forebrain muscarinic receptors (16-fold higher affinity than telenzepine). A biotin conjugate displayed a Ki value of 0.60 nM at m2-receptors and a 5-fold selectivity versus forebrain. The high affinity of these derivatives makes them suitable for the characterization of muscarinic receptors in pharmacological and spectroscopic studies, for peptide mapping, and for histochemical studies. PMID:1520727

  20. Oral Administration of a Retinoic Acid Receptor Antagonist Reversibly Inhibits Spermatogenesis in Mice

    OpenAIRE

    Chung, Sanny S. W.; Wang, Xiangyuan; Roberts, Shelby S.; Stephen M Griffey; Reczek, Peter R.; Wolgemuth, Debra J.

    2011-01-01

    Meeting men's contraceptive needs, orally administered retinoic acid receptor antagonists represent new lead molecules in developing non-hormonal, reversible male contraceptives without adverse side effects.

  1. Does protein binding modulate the effect of angiotensin II receptor antagonists?

    Directory of Open Access Journals (Sweden)

    Marc P Maillard

    2001-03-01

    Full Text Available IntroductionAngiotensin II AT 1-receptor antagonists are highly bound to plasma proteins (≥ 99%. With some antagonists, such as DuP-532, the protein binding was such that no efficacy of the drug could be demonstrated clinically. Whether protein binding interferes with the efficacy of other antagonists is not known. We have therefore investigated in vitro how plasma proteins may affect the antagonistic effect of different AT1-receptor antagonists.MethodsA radio-receptor binding assay was used to analyse the interaction between proteins and the ability of various angiotensin II (Ang II antagonists to block AT1-receptors. In addition, the Biacore technology, a new technique which enables the real-time monitoring of binding events between two molecules, was used to evaluate the dissociation rate constants of five AT1-receptor antagonists from human serum albumin.ResultsThe in vitro AT 1-antagonistic effects of different Ang II receptor antagonists were differentially affected by the presence of human plasma, with rightward shifts of the IC50 ranging from one to several orders of magnitude. The importance of the shift correlates with the dissociation rate constants of these drugs from albumin. Our experiments also show that the way that AT1-receptor antagonists bind to proteins differs from one compound to another. These results suggest that the interaction with plasma proteins appears to modulate the efficacy of some Ang II antagonists.ConclusionAlthough the high binding level of Ang II receptor antagonist to plasma proteins appears to be a feature common to this class of compounds, the kinetics and characteristics of this binding is of great importance. With some antagonists, protein binding interferes markedly with their efficacy to block AT1-receptors.

  2. Crystal structure and pharmacological characterization of a novel N-methyl-D-aspartate (NMDA) receptor antagonist at the GluN1 glycine binding site

    DEFF Research Database (Denmark)

    Kvist, Trine; Steffensen, Thomas Bielefeldt; Greenwood, Jeremy R;

    2013-01-01

    glycine site antagonist, 1-thioxo-1,2-dihydro-[1,2,4]triazolo[4,3-a]quinoxalin-4(5H)-one (TK40). Here, we show by Schild analysis that TK40 is a potent competitive antagonist with Kb values of 21-63 nm at the GluN1 glycine-binding site of the four recombinant GluN1/N2A-D receptors. In addition, TK40...

  3. Effects of 2,3-benzodiazepine AMPA receptor antagonists on dopamine turnover in the striatum of rats with experimental parkinsonism.

    Science.gov (United States)

    Megyeri, Katalin; Marko, Bernadett; Sziray, Nora; Gacsalyi, Istvan; Juranyi, Zsolt; Levay, Gyorgy; Harsing, Laszlo G

    2007-03-15

    Although levodopa is the current "gold standard" for treatment of Parkinson's disease, there has been disputation on whether AMPA receptor antagonists can be used as adjuvant therapy to improve the effects of levodopa. Systemic administration of levodopa, the precursor of dopamine, increases brain dopamine turnover rate and this elevated turnover is believed to be essential for successful treatment of Parkinson's disease. However, long-term treatment of patients with levodopa often leads to development of dyskinesia. Therefore, drugs that feature potentiation of dopamine turnover rate and are able to reduce daily levodopa dosages might be used as adjuvant in the treatment of patients suffering from Parkinson's disease. To investigate such combined treatment, we have examined the effects of two non-competitive AMPA receptor antagonists, GYKI-52466 and GYKI-53405, alone or in combination with levodopa on dopamine turnover rate in 6-hydroxydopamine-lesioned striatum of the rat. We found here that repeated administration of levodopa, added with the peripheral DOPA decarboxylase inhibitor carbidopa, increased dopamine turnover rate after lesioning the striatum with 6-hydroxydopamine. Moreover, combination of levodopa with GYKI-52466 or GYKI-53405 further increased dopamine turnover enhanced by levodopa administration while the AMPA receptor antagonists by themselves failed to influence striatal dopamine turnover. We concluded from the present data that potentiation observed between levodopa and AMPA receptor antagonists may reflect levodopa-sparing effects in clinical treatment indicating the therapeutic potential of such combination in the management of Parkinson's disease.

  4. Molecular properties of psychopharmacological drugs determining non-competitive inhibition of 5-HT3A receptors.

    Science.gov (United States)

    Kornhuber, Johannes; Terfloth, Lothar; Bleich, Stefan; Wiltfang, Jens; Rupprecht, Rainer

    2009-06-01

    We developed a structure-property-activity relationship (SPAR)-model for psychopharmacological drugs acting as non-competitive 5-HT(3A) receptor antagonists by using a decision-tree learner provided by the RapidMiner machine learning tool. A single molecular descriptor, namely the molecular dipole moment per molecular weight (mu/MW), predicts whether or not a substance non-competitively antagonizes 5-HT-induced Na(+) currents. A low mu/MW is compatible with drug-cumulation in apolar lipid rafts. This study confirms that size-intensive descriptors allow the development of compact SPAR models.

  5. Preliminary investigations into triazole derived androgen receptor antagonists.

    Science.gov (United States)

    Altimari, Jarrad M; Niranjan, Birunthi; Risbridger, Gail P; Schweiker, Stephanie S; Lohning, Anna E; Henderson, Luke C

    2014-05-01

    A range of 1,4-substituted-1,2,3-N-phenyltriazoles were synthesized and evaluated as non-steroidal androgen receptor (AR) antagonists. The motivation for this study was to replace the N-phenyl amide portion of small molecule antiandrogens with a 1,2,3-triazole and determine effects, if any, on biological activity. The synthetic methodology presented herein is robust, high yielding and extremely rapid. Using this methodology a series of 17 N-aryl triazoles were synthesized from commercially available starting materials in less than 3h. After preliminary biological screening at 20 and 40 μM, the most promising three compounds were found to display IC50 values of 40-50 μM against androgen dependent (LNCaP) cells and serve as a starting point for further structure-activity investigations. All compounds in this work were the focus of an in silico study to dock the compounds into the human androgen receptor ligand binding domain (hARLBD) and compare their predicted binding affinity with known antiandrogens. A comparison of receptor-ligand interactions for the wild type and T877A mutant AR revealed two novel polar interactions. One with Q738 of the wild type site and the second with the mutated A877 residue.

  6. Orexin receptor antagonists as therapeutic agents for insomnia

    Directory of Open Access Journals (Sweden)

    Ana Clementina Equihua

    2013-12-01

    Full Text Available Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning.Currently, treatment for insomnia involves a combination of cognitive behavioral therapy and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine receptor agonist drugs (GABAA receptor, although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects.Orexin (hypocretin neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g. impaired cognition, disturbed arousal, and motor balance difficulties. However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia.

  7. Discovery and mapping of an intracellular antagonist binding site at the chemokine receptor CCR2

    DEFF Research Database (Denmark)

    Zweemer, Annelien J M; Bunnik, Julia; Veenhuizen, Margo

    2014-01-01

    The chemokine receptor CCR2 is a G protein-coupled receptor that is involved in many diseases characterized by chronic inflammation, and therefore a large variety of CCR2 small molecule antagonists has been developed. On the basis of their chemical structures these antagonists can roughly be divi...

  8. Development of a human vasopressin V1a-receptor antagonist from an evolutionary-related insect neuropeptide

    DEFF Research Database (Denmark)

    Di Giglio, Maria Giulia; Muttenthaler, Markus; Harpsøe, Kasper

    2017-01-01

    Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary...... conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the insect oxytocin/vasopressin orthologue inotocin from the black garden ant (Lasius niger), identified and cloned its cognate receptor and determined its pharmacological properties on the insect and human oxytocin....../vasopressin receptors. Subsequently, we identified a functional dichotomy: inotocin activated the insect inotocin and the human vasopressin V1b receptors, but inhibited the human V1aR. Replacement of Arg8 of inotocin by D-Arg8 led to a potent, stable and competitive V1aR-antagonist ([D-Arg8]-inotocin) with a 3,000-fold...

  9. Testosterone dynamics and psychopathic personality traits independently predict antagonistic behavior towards the perceived loser of a competitive interaction.

    Science.gov (United States)

    Geniole, Shawn N; Busseri, Michael A; McCormick, Cheryl M

    2013-11-01

    Few studies have investigated the influence of changes in testosterone on subsequent competitive, antagonistic behavior in humans. Further, little is known about the extent to which such effects are moderated by personality traits. Here, we collected salivary measures of testosterone before and after a rigged competition. After the competition, participants were given the opportunity to act antagonistically against the competitor (allocate a low honorarium). We hypothesized that changes in testosterone throughout the competition would predict antagonistic behavior such that greater increases would be associated with the allocation of lower honorariums. Further, we investigated the extent to which personality traits related to psychopathy (fearless dominance, FD; self-centered impulsivity, SCI; and coldheartedness) moderated this relationship. In men (n=104), greater increases in testosterone and greater FD were associated with more antagonistic behavior, but testosterone concentrations did not interact with personality measures. In women (n=97), greater FD and SCI predicted greater antagonistic behavior, but there were no significant endocrine predictors or interactions with personality measures. In a secondary set of analyses, we found no support for the dual-hormone hypothesis that the relationship between baseline testosterone concentrations and behavior is moderated by cortisol concentrations. Thus, results are consistent with previous findings that in men, situation-specific testosterone reactivity rather than baseline endocrine function is a better predictor of future antagonistic behavior. The results are discussed with respect to the Challenge Hypothesis and the Biosocial Model of Status, and the possible mechanisms underlying the independent relations of testosterone and personality factors with antagonistic behavior.

  10. Bicuculline, a GABAA-receptor antagonist, blocked HPA axis activation induced by ghrelin under an acute stress.

    Science.gov (United States)

    Gastón, M S; Cid, M P; Salvatierra, N A

    2017-03-01

    Ghrelin is a peptide of 28 amino acids with a homology between species, which acts on the central nervous system to regulate different actions, including the control of growth hormone secretion and metabolic regulation. It has been suggested that central ghrelin is a mediator of behavior linked to stress responses and induces anxiety in rodents and birds. Previously, we observed that the anxiogenic-like behavior induced by ghrelin injected into the intermediate medial mesopallium (IMM) of the forebrain was blocked by bicuculline (a GABAA receptor competitive antagonist) but not by diazepam (a GABAA receptor allosteric agonist) in neonatal meat-type chicks (Cobb). Numerous studies have indicated that hypothalamic-pituitary-adrenal (HPA) axis activation mediates the response to stress in mammals and birds. However, it is still unclear whether this effect of ghrelin is associated with HPA activation. Therefore, we investigated whether anxiety behavior induced by intra-IMM ghrelin and mediated through GABAA receptors could be associated with HPA axis activation in the neonatal chick. In the present study, in an Open Field test, intraperitoneal bicuculline methiodide blocked anxiogenic-like behavior as well as the increase in plasma ACTH and corticosterone levels induced by ghrelin (30pmol) in neonatal chicks. Moreover, we showed for the first time that a competitive antagonist of GABAA receptor suppressed the HPA axis activation induced by an anxiogenic dose of ghrelin. These results show that the anxiogenic ghrelin action involves the activation of the HPA axis, with a complex functional interaction with the GABAA receptor.

  11. HETEROGENEOUS RECEPTOR-BINDING OF CLASSICAL QUATERNARY MUSCARINIC ANTAGONISTS .1. BOVINE TISSUE DISTRIBUTION

    NARCIS (Netherlands)

    ROFFEL, AF; ENSING, K; INTHOUT, WG; DEZEEUW, RA; ZAAGSMA, J

    1991-01-01

    In competition experiments with the teritiary radioligand [H-3]dexetimide, classical quaternary muscarinic antagonists like ipratropium bromide and N-methylscopolamine bromide distinguished two muscarinic binding sites in bovine brain (total brain minus cerebellum) membranes, in contrast to their

  12. Histamine and histamine receptor antagonists in cancer biology.

    Science.gov (United States)

    Blaya, Bruno; Nicolau-Galmés, Francesca; Jangi, Shawkat M; Ortega-Martínez, Idoia; Alonso-Tejerina, Erika; Burgos-Bretones, Juan; Pérez-Yarza, Gorka; Asumendi, Aintzane; Boyano, María D

    2010-07-01

    Histamine has been demonstrated to be involved in cell proliferation, embryonic development, and tumour growth. These various biological effects are mediated through the activation of specific histamine receptors (H1, H2, H3, and H4) that differ in their tissue expression patterns and functions. Although many in vitro and in vivo studies of the modulatory roles of histamine in tumour development and metastasis have been reported, the effect of histamine in the progression of some types of tumours remains controversial; however, recent findings on the role of histamine in the immune system have shed new light on this question. This review focuses on the recent advances in understanding the roles of histamine and its receptors in tumour biology. We report our recent observations of the anti-tumoural effect of H1 histamine antagonists on experimental and human melanomas. We have found that in spite of exogenous histamine stimulated human melanoma cell proliferation, clonogenic ability and migration activity in a dose-dependent manner, the melanoma tumour growth was not modulated by in vivo histamine treatment. On the contrary, terfenadine-treatment in vitro induced melanoma cell death by apoptosis and in vivo terfenadine treatment significantly inhibited tumour growth in murine models. These observations increase our understanding of cancer biology and may inspire novel anticancer therapeutic strategies.

  13. Montelukast: More than a Cysteinyl Leukotriene Receptor Antagonist?

    Directory of Open Access Journals (Sweden)

    Gregory R. Tintinger

    2010-01-01

    Full Text Available The prototype cysteinyl leukotriene receptor antagonist, montelukast, is generally considered to have a niche application in the therapy of exercise- and aspirin-induced asthma. It is also used as add-on therapy in patients whose asthma is poorly controlled with inhaled corticosteroid monotherapy, or with the combination of a long-acting β(2-agonist and an inhaled corticosteroid. Recently, however, montelukast has been reported to possess secondary anti-inflammatory properties, apparently unrelated to conventional antagonism of cysteinyl leukotriene receptors. These novel activities enable montelukast to target eosinophils, monocytes, and, in particular, the corticosteroid-insensitive neutrophil, suggesting that this agent may have a broader spectrum of anti-inflammatory activities than originally thought. If so, montelukast is potentially useful in the chemotherapy of intermittent asthma, chronic obstructive pulmonary disease, cystic fibrosis, and viral bronchiolitis, which, to a large extent, involve airway epithelial cell/neutrophil interactions. The primary objective of this mini-review is to present evidence for the cysteinyl leukotrien–independent mechanisms of action of montelukast and their potential clinical relevance.

  14. Characterization of bicuculline/baclofen-insensitive (rho-like) gamma-aminobutyric acid receptors expressed in Xenopus oocytes. II. Pharmacology of gamma-aminobutyric acidA and gamma-aminobutyric acidB receptor agonists and antagonists.

    Science.gov (United States)

    Woodward, R M; Polenzani, L; Miledi, R

    1993-04-01

    Poly(A)+ RNA from mammalian retina expresses bicuculline/baclofen-insensitive gamma-aminobutyric acid (GABA) receptors in Xenopus oocytes with properties similar to those of homooligomeric GABA rho 1 receptors. The pharmacological profile of these rho-like receptors was extended by measuring sensitivities to various GABAA and GABAB receptor ligands. For direct comparison the same compounds were also assayed with GABAA receptors expressed by rat brain RNA. The potency sequence for heterocyclic GABA analogues at the GABA rho-like receptors was GABA (1.3) > muscimol (2.3) > isoguvacine (100) (approximate EC50 in parentheses; all EC50 and Kb values given in microM). Both muscimol and isoguvacine were partial agonists at the rho-like receptors. 4,5,6,7-Tetrahydroisoxazolo[5,4-c]pyridin-3-ol (Kb congruent to 32), piperidine-4-sulfonic acid (Kb congruent to 85), and isonipecotic acid (Kb congruent to 1000) acted primarily as competitive antagonists, showing little or no activity as agonists. The sulfonic acid GABA analogue 3-aminopropanesulfonic acid was also a competitive antagonist (Kb congruent to 20). Conformationally restricted GABA analogues trans- and cis-4-aminocrotonic acid (TACA and CACA) were agonists at the rho-like receptors. TACA (EC50 congruent to 0.6) had twice the potency of GABA and was 125 times more potent than CACA (EC50 congruent to 75). Z-3-(Amidinothio)propenoic acid, an isothiouronium analogue of GABA, had little activity as an agonist but instead acted as a competitive antagonist (Kb congruent to 20). At concentrations of > 100 microM, bicuculline did have some weak competitive inhibitory effects on the GABA rho-like receptors (Kb congruent to 6000), but it was at least 5000 times more potent at GABAA receptors. Strychnine (Kb congruent to 70) and SR-95531 (Kb congruent to 35) also were competitive inhibitors of the rho-like receptors but were, respectively, 20 and 240 times more potent at GABAA receptors. The GABAB receptor ligands baclofen

  15. Dihydromorphine-peptide hybrids with delta receptor agonistic and mu receptor antagonistic actions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.B.; Medzihradsky, F.; Woods, J.H.

    1986-03-05

    The actions of two morphine derivatives with short peptide side chains were evaluated upon the contraction of the isolated mouse vas deferens and upon displacement of /sup 3/H-etorphine from rat brain membranes. NIH-9833 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-phenylalanyl-L-leucine ethyl ester HCl) was a potent agonist upon the vas deferens. Its EC50 for inhibition of the twitch was 1.2 +/- 0.1 nM. Both naltrexone (10/sup -7/ M) a relatively nonselective opioid antagonist, and ICI-174864 (10/sup -/' M) a highly selective delta receptor antagonist, blocked the actions of NIH-9833 which indicates that this drug is a delta receptor agonist. In contrast, NIH-9835 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-glycyl-L-phenylalanyl-L-leucine ethyl ester HCl), which differs from NIH-9835 by the presence of a single amino acid residue, was devoid of opioid agonistic activity but was a potent antagonist of the inhibitory actions on the vas deferens of morphine and sufentanil. NIH-9833 and NIH-9835 were potent displacers of /sup 3/H-etorphine from rat cerebral membranes with EC50's of 0.58 nM and 1.7 nM, respectively. The observation that addition of a single glycyl group changes a dihydromorphine-peptide analog from a potent delta receptor agonist to an equally potent mu receptor antagonist suggests that the two receptor sites might be structurally quite similar.

  16. Development of selective agonists and antagonists of P2Y receptors

    OpenAIRE

    2008-01-01

    Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were report...

  17. Value of the radiolabelled GLP-1 receptor antagonist exendin(9-39) for targeting of GLP-1 receptor-expressing pancreatic tissues in mice and humans

    Energy Technology Data Exchange (ETDEWEB)

    Waser, Beatrice; Reubi, Jean Claude [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, P.O. Box 62, Bern (Switzerland)

    2011-06-15

    Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. Moreover, it was recently reported that antagonist tracers were superior to agonist tracers for somatostatin and gastrin-releasing peptide receptor targeting of tumours. The present preclinical study determines therefore the value of an established GLP-1 receptor antagonist for the in vitro visualization of GLP-1 receptor-expressing tissues in mice and humans. Receptor autoradiography studies with {sup 125}I-GLP-1(7-36)amide agonist or {sup 125}I-Bolton-Hunter-exendin(9-39) antagonist radioligands were performed in mice pancreas and insulinomas as well as in human insulinomas; competition experiments were performed in the presence of increasing concentration of GLP-1(7-36)amide or exendin(9-39). The antagonist {sup 125}I-Bolton-Hunter-exendin(9-39) labels mouse pancreatic {beta}-cells and mouse insulinomas, but it does not label human pancreatic {beta}-cells and insulinomas. High affinity displacement (IC{sub 50} approximately 2 nM) is observed in mouse {beta}-cells and insulinomas with either the exendin(9-39) antagonist or GLP-1(7-36)amide agonist. For comparison, the agonist {sup 125}I-GLP-1(7-36)amide intensively labels mouse pancreatic {beta}-cells, mouse insulinoma and human insulinomas; high affinity displacement is observed for the GLP-1(7-36)amide in all tissues; however, a 5 and 20 times lower affinity is found for exendin(9-39) in the mouse and human tissues, respectively. This study reports a species-dependent behaviour of the GLP-1 receptor antagonist exendin(9-39) that can optimally target GLP-1 receptors in mice but not in human tissue. Due to its overly low binding affinity, this antagonist is an inadequate targeting agent for human GLP-1 receptor-expressing tissues, as opposed to the GLP-1 receptor agonist, GLP-1(7-36)amide. (orig.)

  18. Discovery of the first small-molecule opioid pan antagonist with nanomolar affinity at mu, delta, kappa, and nociceptin opioid receptors.

    Science.gov (United States)

    Zaveri, Nurulain T; Journigan, V Blair; Polgar, Willma E

    2015-04-15

    The trans-(3R,4R)-dimethyl-4-(3-hydroxyphenyl)piperidine scaffold is a known pharmacophore for mu opioid (MOP), kappa opioid (KOP), and delta opioid (DOP) receptor antagonists; however, it has not been explored in nociceptin opioid (NOP/ORL-1) receptor ligands. We recently found that the selective KOP antagonist JDTic, (3R)-7-hydroxy-N-((1S)-1-{[(3R,4R)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidinyl]methyl}-2-methylpropyl)-1,2,3,4-tetrahydro-3-isoquinolinecarboxamide, containing this opioid antagonist pharmacophore, has significant binding affinity at the NOP receptor (Ki 16.67 ± 0.76 nM), with no intrinsic activity in the [(35)S]GTPγS functional assay. Since this is the first ligand containing the trans-(3R,4R)-dimethyl-4-(3-hydroxyphenyl)piperidine opioid antagonist pharmacophore to have affinity for the NOP receptor, we explored the structural determinants of its NOP binding affinity. When rational chemical modifications of JDTic were carried out, based on our previously established NOP pharmacophoric structure-activity relationship (SAR) model, most modifications led to a significant decrease in NOP and opioid binding affinity compared to JDTic. Interestingly, however, removal of the 3,4-dimethyl groups of the trans-(3R,4R)-dimethyl-4-(3-hydroxyphenyl)piperidine antagonist scaffold of JDTic increased the binding affinity at NOP by 10-fold (Ki 1.75 ± 0.74 nM) while maintaining comparable affinity for KOP, MOP, and DOP receptors (Ki 1.14 ± 0.63, 1.67 ± 0.6, and 19.6 ± 1.3 nM, respectively). In vitro functional efficacy studies using the [(35)S]GTPγS assay showed that this compound AT-076 functions as an antagonist at all four opioid receptors. Detailed characterization of the antagonist activity of AT-076 shows that it has a noncompetitive antagonist profile at the NOP and KOP receptors (insurmountable antagonism), but is a potent competitive antagonist at the MOP and DOP receptors, with Ke values 3-6-fold more potent than those of JDTic. AT-076 is the

  19. Dopamine D(3) receptor antagonists: The quest for a potentially selective PET ligand. Part two: Lead optimization.

    Science.gov (United States)

    Micheli, Fabrizio; Holmes, Ian; Arista, Luca; Bonanomi, Giorgio; Braggio, Simone; Cardullo, Francesca; Di Fabio, Romano; Donati, Daniele; Gentile, Gabriella; Hamprecht, Dieter; Terreni, Silvia; Heidbreder, Christian; Savoia, Chiara; Griffante, Cristiana; Worby, Angela

    2009-08-01

    The lead optimization process to identify new selective dopamine D(3) receptor antagonists is reported. DMPK parameters and binding data suggest that selective D(3) receptor antagonists as potential PET ligands might have been identified.

  20. Anticonvulsive effect of nonimidazole histamine H3 receptor antagonists.

    Science.gov (United States)

    Sadek, Bassem; Kuder, Kamil; Subramanian, Dhanasekaran; Shafiullah, Mohamed; Stark, Holger; Lażewska, Dorota; Adem, Abdu; Kieć-Kononowicz, Katarzyna

    2014-06-01

    To determine the potential of histamine H3 receptor (H3R) ligands as new antiepileptic drugs (AEDs), aromatic ether, and diether derivatives (1-12) belonging to the nonimidazole class of ligands, with high in-vitro binding affinity at human H3R, were tested for their in-vivo anticonvulsive activity in the maximal electroshock (MES)-induced and pentylenetetrazole (PTZ)-kindled seizure models in rats. The anticonvulsive effects of a systemic injection of 1-12 on MES-induced and PTZ-kindled seizures were evaluated against the reference AED phenytoin (PHT) and the structurally related H3R antagonist/inverse agonist pitolisant (PIT). Among the most promising ligands 2, 4, 5, and 11, there was a significant and dose-dependent reduction in the duration of tonic hind limb extension (THLE) in MES-induced seizure subsequent to administration of 4 and 5 [(5, 10, and 15 mg/kg, intraperitoneally (i.p.)]. The protective effects observed for the 1-(3-(3-(4-chlorophenyl)propoxy)propyl)-3-methylpiperidine derivative 11 at 10 mg/kg, i.p. were significantly greater than those of PIT, and were reversed by pretreatment with the central nervous system penetrant H1R antagonist pyrilamine (PYR) (10 mg/kg). Moreover, the protective action of the reference AED PHT, at a dose of 5 mg/kg (without considerable protection in the MES model), was significantly augmented when coadministered with derivative 11 (5 mg/kg, i.p.). Surprisingly, pretreatment with derivative 7 (10 mg/kg, i.p.), an ethylphenoxyhexyl-piperidine derivative without considerable protection in the MES model, potently altered PTZ-kindled seizure, significantly prolonged myoclonic latency time, and clearly shortened the total seizure time when compared with control, PHT, and PIT. These interesting results highlight the potential of H3R ligands as new AEDs or as adjuvants to available AED therapeutics.

  1. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

    Directory of Open Access Journals (Sweden)

    Sadek B

    2016-11-01

    , in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-ylpropoxyphenylmethanol, and its (S-enantiomer (4 significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R-enantiomer (3 in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and reversed when rats were pretreated with the selective H3R agonist R-(α-methyl-histamine. Comparisons of the observed antagonistic in vitro affinities among the ligands 1–6 revealed profound stereoselectivity at human H3Rs with varying preferences for this receptor subtype. Moreover, the in vivo anticonvulsant effects observed in this study for ligands 1–6 showed stereoselectivity in different convulsion models in male adult rats. Keywords: histamine, H3 receptor, isomeric antagonists, anticonvulsant activity, stereo­selectivity

  2. Inhibition of tryptase release from human colon mast cells by histamine receptor antagonists.

    Science.gov (United States)

    He, Shao-Heng; Xie, Hua; Fu, Yi-Ling

    2005-03-01

    The main objective of this study was to investigate the ability of histamine receptor antagonists to modulate tryptase release from human colon mast cells induced by histamine. Enzymatically dispersed cells from human colon were challenged with histamine in the absence or presence of the histamine receptor antagonists, and the tryptase release was determined. It was found that histamine induced tryptase release from colon mast cells was inhibited by up to approximately 61.5% and 24% by the H1 histamine receptor antagonist terfenadine and the H2 histamine receptor antagonist cimetidine, respectively, when histamine and its antagonists were added to cells at the same time. The H3 histamine receptor antagonist clobenpropit had no effect on histamine induced tryptase release from colon mast cells at all concentrations tested. Preincubation of terfenadine, cimetidine or clobenpropit with cells for 20 minutes before challenging with histamine did not enhance the ability of these antihistamines to inhibit histamine induced tryptase release. Apart from terfenadine at 100 microg/ml, the antagonists themselves did not stimulate tryptase release from colon mast cells following both 15 minutes and 35 minutes incubation periods. It was concluded that H1 and H2 histamine receptor antagonists were able to inhibit histamine induced tryptase release from colon mast cells. This not only added some new data to our hypothesis of self-amplification mechanisms of mast cell degranulation, but also suggested that combining these two types of antihistamine drugs could be useful for the treatment of inflammatory bowel disease (IBD).

  3. Synthesis and Dual Histamine H1 and H2 Receptor Antagonist Activity of Cyanoguanidine Derivatives

    OpenAIRE

    2013-01-01

    Premedication with a combination of histamine H1 receptor (H1R) and H2 receptor (H2R) antagonists has been suggested as a prophylactic principle, for instance, in anaesthesia and surgery. Aiming at pharmacological hybrids combining H1R and H2R antagonistic activity, a series of cyanoguanidines 14–35 was synthesized by linking mepyramine-type H1R antagonist substructures with roxatidine-, tiotidine-, or ranitidine-type H2R antagonist moieties. N-desmethylmepyramine was connected via a poly-met...

  4. Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model

    DEFF Research Database (Denmark)

    Chan, K Y; Gupta, S; de Vries, R;

    2010-01-01

    studies have shown that glutamate receptor antagonists affect the pathophysiology of migraine. This study investigated whether antagonists of NMDA (ketamine and MK801), AMPA (GYKI52466) and kainate (LY466195) glutamate receptors affected dural vasodilatation induced by alpha-CGRP, capsaicin......During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical...

  5. Sisters' curse: sexually antagonistic effects constrain the spread of a mitochondrial haplogroup superior in sperm competition.

    Science.gov (United States)

    Padua, Michael V; Zeh, David W; Bonilla, Melvin M; Zeh, Jeanne A

    2014-12-22

    Maternal inheritance of mitochondria creates a sex-specific selective sieve with implications for male longevity, disease susceptibility and infertility. Because males are an evolutionary dead end for mitochondria, mitochondrial mutations that are harmful or beneficial to males but not females cannot respond directly to selection. Although the importance of this male/female asymmetry in evolutionary response depends on the extent to which mitochondrial mutations exert antagonistic effects on male and female fitness, few studies have documented sex-specific selection acting on mitochondria. Here, we exploited the discovery of two highly divergent mitochondrial haplogroups (A and B2) in central Panamanian populations of the pseudoscorpion Cordylochernes scorpioides. Next-generation sequencing and phylogenetic analyses suggest that selection on the ND4 and ND4L mitochondrial genes may partially explain sexually antagonistic mitochondrial effects on reproduction. Males carrying the rare B2 mitochondrial haplogroup enjoy a marked advantage in sperm competition, but B2 females are significantly less sexually receptive at second mating than A females. This reduced propensity for polyandry is likely to significantly reduce female lifetime reproductive success, thereby limiting the spread of the male beneficial B2 haplogroup. Our findings suggest that maternal inheritance of mitochondria and sexually antagonistic selection can constrain male adaptation and sexual selection in nature.

  6. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

    Science.gov (United States)

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  7. Endothelin receptor B antagonists decrease glioma cell viability independently of their cognate receptor

    Directory of Open Access Journals (Sweden)

    Patterson Paul H

    2008-11-01

    Full Text Available Abstract Background Endothelin receptor antagonists inhibit the progression of many cancers, but research into their influence on glioma has been limited. Methods We treated glioma cell lines, LN-229 and SW1088, and melanoma cell lines, A375 and WM35, with two endothelin receptor type B (ETRB-specific antagonists, A-192621 and BQ788, and quantified viable cells by the capacity of their intracellular esterases to convert non-fluorescent calcein AM into green-fluorescent calcein. We assessed cell proliferation by labeling cells with carboxyfluorescein diacetate succinimidyl ester and quantifying the fluorescence by FACS analysis. We also examined the cell cycle status using BrdU/propidium iodide double staining and FACS analysis. We evaluated changes in gene expression by microarray analysis following treatment with A-192621 in glioma cells. We examined the role of ETRB by reducing its expression level using small interfering RNA (siRNA. Results We report that two ETRB-specific antagonists, A-192621 and BQ788, reduce the number of viable cells in two glioma cell lines in a dose- and time-dependent manner. We describe similar results for two melanoma cell lines. The more potent of the two antagonists, A-192621, decreases the mean number of cell divisions at least in part by inducing a G2/M arrest and apoptosis. Microarray analysis of the effects of A-192621 treatment reveals up-regulation of several DNA damage-inducible genes. These results were confirmed by real-time RT-PCR. Importantly, reducing expression of ETRB with siRNAs does not abrogate the effects of either A-192621 or BQ788 in glioma or melanoma cells. Furthermore, BQ123, an endothelin receptor type A (ETRA-specific antagonist, has no effect on cell viability in any of these cell lines, indicating that the ETRB-independent effects on cell viability exhibited by A-192621 and BQ788 are not a result of ETRA inhibition. Conclusion While ETRB antagonists reduce the viability of glioma cells

  8. INTRACEREBROVENTRICULAR APPLICATION OF COMPETITIVE AND NONCOMPETITIVE NMDA ANTAGONISTS INDUCE SIMILAR EFFECTS UPON RAT HIPPOCAMPAL ELECTROENCEPHALOGRAM AND LOCAL CEREBRAL GLUCOSE-UTILIZATION

    NARCIS (Netherlands)

    BODDEKE, HWGM; WIEDERHOLD, KH; PALACIOS, JM

    1992-01-01

    In this study we have used electrophysiological and metabolic markers to investigate the effects of competitive and non-competitive NMDA antagonists in rats after central or peripheral administration. The non-competitive antagonist, MK-801, induced dose-dependent suppression of rat hippocampal EEG e

  9. Development of prolactin receptor antagonists with reduced pH-dependence of receptor binding

    DEFF Research Database (Denmark)

    Hansen, Mathilde Johanne Kaas; Olsen, Johan Gotthardt; Bernichtein, Sophie;

    2011-01-01

    H than at physiological pH and since the extracellular environment around solid tumors often is acidic, it is desirable to develop antagonists that have improved binding affinity at low pH. The pK(a) value of a histidine side chain is ~6.8 making histidine residues obvious candidates for examination....... From evaluation of known molecular structures of human prolactin, of the prolactin receptor and of different complexes of the two, three histidine residues in the hormone-receptor binding site 1 were selected for mutational studies. We analyzed 10 variants by circular dichroism spectroscopy, affinity...... and thermodynamic characterization of receptor binding by isothermal titration calorimetry combined with in vitro bioactivity in living cells. Histidine residue 27 was recognized as a central hot spot for pH sensitivity and conservative substitutions at this site resulted in strong receptor binding at low pH. Pure...

  10. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    Science.gov (United States)

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  11. The muscle relaxant thiocolchicoside is an antagonist of GABAA receptor function in the central nervous system.

    Science.gov (United States)

    Carta, Mario; Murru, Luca; Botta, Paolo; Talani, Giuseppe; Sechi, GianPietro; De Riu, PierLuigi; Sanna, Enrico; Biggio, Giovanni

    2006-09-01

    Thiocolchicoside (TCC) is used clinically for its muscle relaxant, anti-inflammatory, and analgesic properties, and it has been shown to interact with gamma-aminobutyric acid (GABA) type A receptors (GABAARs) and strychnine-sensitive glycine receptors in the rat central nervous system. In contrast to a proposed agonistic action at these two types of inhibitory receptors, pharmacological evidence has shown that, under certain conditions, TCC manifests convulsant activity in animals and humans. We now show that the phasic and tonic GABAAR-mediated currents recorded from Purkinje cells and granule neurons, respectively, in parasagittal cerebellar slices from adult male rats were inhibited by TCC in a concentration-dependent manner. The median inhibitory concentrations of TCC for these effects were approximately 0.15 and approximately 0.9 microM, respectively. TCC did not potentiate GABABR-mediated currents in hippocampal slices, suggesting that its muscle relaxant action is not mediated by GABABRs. Intraperitoneal injection of TCC in rats either alone or in combination with negative modulators of GABAergic transmission revealed convulsant and proconvulsant actions of this drug. Our data, consistent with clinical observations of the epileptogenic effect of this compound, suggest that TCC is a potent competitive antagonist of GABAAR function.

  12. A novel thromboxane receptor antagonist, nstpbp5185, inhibits platelet aggregation and thrombus formation in animal models.

    Science.gov (United States)

    Huang, Shiu-Wen; Kuo, Heng-Lan; Hsu, Ming-Tsung; Tseng, Yufeng Jane; Lin, Shu-Wha; Kuo, Sheng-Chu; Peng, Hui-Chin; Lien, Jin-Cherng; Huang, Tur-Fu

    2016-08-01

    A novel benzimidazole derivative, nstpbp5185, was discovered through in vitro and in vivo evaluations for antiplatelet activity. Thromaboxane receptor (TP) is important in vascular physiology, haemostasis and pathophysiological thrombosis. Nstpbp5185 concentration-dependently inhibited human platelet aggregation caused by collagen, arachidonic acid and U46619. Nstpbp5185 caused a right-shift of the concentration-response curve of U46619 and competitively inhibited the binding of 3H-SQ-29548 to TP receptor expressed on HEK-293 cells, with an IC50 of 0.1 µM, indicating that nstpbp5185 is a TP antagonist. In murine thrombosis models, nstpbp5185 significantly prolonged the latent period in triggering platelet plug formation in mesenteric and FeCl3-induced thrombi formation, and increased the survival rate in pulmonary embolism model with less bleeding than aspirin. This study suggests nstpbp5185, an orally selective anti-thrombotic agent, acting through blockade of TXA2 receptor, may be efficacious for prevention or treatment of pathologic thrombosis.

  13. Effects of the NMDA receptor antagonists on deltamethrin-induced striatal dopamine release in conscious unrestrained rats.

    Science.gov (United States)

    Morikawa, Takuya; Furuhama, Kazuhisa

    2009-08-01

    To better understand the neurotoxicity caused by the pyrethroid pesticide, we examined the effects of the N-methyl-D-aspartate (NMDA) receptor antagonists MK-801, a non-competitive cation channel blocker, and 2-amino-5-phosphonovaleric acid (APV), a competitive Na(+) channel blocker, on extracellular dopamine levels in male Sprague-Dawley rats receiving the type II pyrethroid deltamethrin using an in vivo microdialysis system. Deltamethrin (60 mg/kg, i.p.) evidently increased striatal dopamine levels with a peak time of 120 min, and the local infusion (i.c.) of either MK-801(650 muM) or APV (500 muM) completely blocked these actions. The fluctuation in the dopamine metabolite 3-MT also resembled that in dopamine. Our results suggest that dopamine-releasing neurons would be modulated via the NMDA receptor by the excitatory glutamatergic neurons after deltamethrin treatment.

  14. Iontophoresis of endothelin receptor antagonists in rats and men.

    Directory of Open Access Journals (Sweden)

    Matthieu Roustit

    Full Text Available INTRODUCTION: The treatment of scleroderma-related digital ulcers is challenging. The oral endothelin receptor antagonist (ERA bosentan has been approved but it may induce liver toxicity. The objective of this study was to test whether ERAs bosentan and sitaxentan could be locally delivered using iontophoresis. METHODS: Cathodal and anodal iontophoresis of bosentan and sitaxentan were performed on anaesthetized rat hindquarters without and during endothelin-1 infusion. Skin blood flow was quantified using laser-Doppler imaging and cutaneous tolerability was assessed. Iontophoresis of sitaxentan (20 min, 20 or 100 µA was subsequently performed on the forearm skin of healthy men (n = 5. RESULTS: In rats neither bosentan nor sitaxentan increased skin blood flux compared to NaCl. When simultaneously infusing endothelin-1, cathodal iontophoresis of sitaxentan increased skin blood flux compared to NaCl (AUC(0-20 were 44032.2 ± 12277 and 14957.5 ± 23818.8 %BL.s, respectively; P = 0.01. In humans, sitaxentan did not significantly increase skin blood flux as compared to NaCl. Iontophoresis of ERAs was well tolerated both in animals and humans. CONCLUSIONS: This study shows that cathodal iontophoresis of sitaxentan but not bosentan partially reverses endothelin-induced skin vasoconstriction in rats, suggesting that sitaxentan diffuses into the dermis. However, sitaxentan does not influence basal skin microvascular tone in rats or in humans.

  15. Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure.

    Science.gov (United States)

    Sica, Domenic A

    2015-01-01

    Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered.

  16. Modulation of glutamate transport and receptor binding by glutamate receptor antagonists in EAE rat brain.

    Science.gov (United States)

    Sulkowski, Grzegorz; Dąbrowska-Bouta, Beata; Salińska, Elżbieta; Strużyńska, Lidia

    2014-01-01

    The etiology of multiple sclerosis (MS) is currently unknown. However, one potential mechanism involved in the disease may be excitotoxicity. The elevation of glutamate in cerebrospinal fluid, as well as changes in the expression of glutamate receptors (iGluRs and mGluRs) and excitatory amino acid transporters (EAATs), have been observed in the brains of MS patients and animals subjected to experimental autoimmune encephalomyelitis (EAE), which is the predominant animal model used to investigate the pathophysiology of MS. In the present paper, the effects of glutamatergic receptor antagonists, including amantadine, memantine, LY 367583, and MPEP, on glutamate transport, the expression of mRNA of glutamate transporters (EAATs), the kinetic parameters of ligand binding to N-methyl-D-aspartate (NMDA) receptors, and the morphology of nerve endings in EAE rat brains were investigated. The extracellular level of glutamate in the brain is primarily regulated by astrocytic glutamate transporter 1 (GLT-1) and glutamate-aspartate transporter (GLAST). Excess glutamate is taken up from the synaptic space and metabolized by astrocytes. Thus, the extracellular level of glutamate decreases, which protects neurons from excitotoxicity. Our investigations showed changes in the expression of EAAT mRNA, glutamate transport (uptake and release) by synaptosomal and glial plasmalemmal vesicle fractions, and ligand binding to NMDA receptors; these effects were partially reversed after the treatment of EAE rats with the NMDA antagonists amantadine and memantine. The antagonists of group I metabotropic glutamate receptors (mGluRs), including LY 367385 and MPEP, did not exert any effect on the examined parameters. These results suggest that disturbances in these mechanisms may play a role in the processes associated with glutamate excitotoxicity and the progressive brain damage in EAE.

  17. ASSESSMENT OF EFFICACY OF LEUKOTRIENE RECEPTOR ANTAGONISTS IN THERAPY OF BRONCHIAL ASTHMA IN CHILDREN

    Directory of Open Access Journals (Sweden)

    Yu.G. Levina

    2009-01-01

    Full Text Available The article provides data regarding the clinical efficacy and safety of leukotriene receptor antagonists in treatment of bronchial asthma in children. The only representative of this group that is allowed in Russia for treatment of children over 6 years of age is Montelukast. Approval of new 4 mg dosage of Montelukast for children from 2 years of age is expected in Russia in July 2009. Leukotriene receptor antagonists have a high safety profile and can be used as an alternative first-line therapy for persistent asthma.Key words: leukotriene receptor antagonists, montelukast, bronchial asthma, children.

  18. The substance P/NK-1 receptor system: NK-1 receptor antagonists as anti-cancer drugs

    Indian Academy of Sciences (India)

    Miguel Muñoz; Rafael Coveñas; Francisco Esteban; Maximino Redondo

    2015-06-01

    The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in cancer. SP promotes the proliferation of tumour cells, angiogenesis and the migration of tumour cells. We review the involvement of SP, the NK-1 receptor and NK-1 receptor antagonists in cancer. Tumour cells overexpress NK-1 receptors, which are involved in their viability. This overexpression suggests the possibility of specific treatment against tumour cells using NK-1 receptor antagonists, thus promoting a considerable decrease in the side effects of the treatment. This strategy opens up new approaches for cancer treatment, since these antagonists, after binding to their molecular target, induce the death of tumour cells by apoptosis, exert an antiangiogenic action and inhibit the migration of tumour cells. The use of NK-1 receptor antagonists such as aprepitant (used in clinical practice) as antitumour agents could be a promising innovation. The value of aprepitant as an antitumour agent could be determined faster than for less well-known compounds because many studies addressing its safety and characterization have already been completed. The NK-1 receptor may be a promising target in the treatment of cancer; NK-1 receptor antagonists could act as specific drugs against tumour cells; and these antagonists could be new candidate anti-cancer drugs.

  19. The NK1 receptor antagonist L822429 reduces heroin reinforcement.

    Science.gov (United States)

    Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

    2013-05-01

    Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects.

  20. Different affinity states of alpha-1 adrenergic receptors defined by agonists and antagonists in bovine aorta plasma membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jagadeesh, G.; Deth, R.C.

    1987-11-01

    Evidence for a nonlinear relationship between alpha-1 adrenergic receptor occupancy and tissue responses, together with the finding of different affinity states for agonist binding, has raised the possibility of functional heterogeneity of alpha-1 adrenergic receptors. We have conducted studies to examine: 1) binding characteristics of (/sup 3/H)prazosin, 2) competition of antagonists at these sites and 3) different affinity states of the receptor for agonists and modulation of these states by 5'-guanylylimidodiphosphate (Gpp(NH)p). A plasma membrane-enriched vesicular fraction (F2; 15%/33% sucrose interphase) was prepared from the muscular medial layer of bovine thoracic aorta. (/sup 3/H)Prazosin binding was characterized by a monophasic saturation isotherm (KD = 0.116 nM, Bmax = 112 fmol/mg of protein). Antagonist displacement studies yielded a relative potency order of prazosin greater than or equal to WB4104 much greater than phentolamine greater than corynanthine greater than yohimbine greater than or equal to idazoxan greater than rauwolscine. Competition curves for unlabeled prazosin, WB4101 (2-(2,6-dimethoxyphenoxyethyl)-aminomethyl-1,4 benzodioxane) and phentolamine were shallow and were best modeled to two binding sites with picomolar and nanomolar KD values. Gpp(NH)p was without effect on antagonist affinity. Agonist (epinephrine, norepinephrine and phenylephrine) competition with (/sup 3/H)prazosin binding was biphasic with pseudo-Hill slopes less than 1.0. Binding was best described by a two-site model in which the average contribution of high affinity sites was 23% of total binding. KD values for the high affinity site ranged from 2.9 to 18 nM, and 3.9 to 5.0 microM for the low affinity site.

  1. INCREASED PLASMA-CONCENTRATIONS OF INTERLEUKIN-1 RECEPTOR ANTAGONIST IN NEONATAL SEPSIS

    NARCIS (Netherlands)

    DEBONT, ESJM; DELEIJ, LHFM; OKKEN, A; BAARSMA, R; KIMPEN, JLL

    Newborns are prone to severe infections and sepsis. Cytokines such as tumor necrosis factor-alpha and IL-1 beta play a major role in the initiation of the host response to infections. IL-1 receptor antagonist (IL-1ra) is a naturally occurring antagonist of IL-1 beta. we hypothesized that low IL-1ra

  2. Recombinant human interleukin-1 receptor antagonist in severe traumatic brain injury: a phase II randomized control trial.

    Science.gov (United States)

    Helmy, Adel; Guilfoyle, Mathew R; Carpenter, Keri L H; Pickard, John D; Menon, David K; Hutchinson, Peter J

    2014-05-01

    Traumatic brain injury (TBI) is the commonest cause of death and disability in those aged under 40 years. Interleukin-1 receptor antagonist (IL1ra) is an endogenous competitive antagonist at the interleukin-1 type-1 receptor (IL-1R). Antagonism at the IL-1R confers neuroprotection in several rodent models of neuronal injury (i.e., trauma, stroke and excitotoxicity). We describe a single center, phase II, open label, randomized-control study of recombinant human IL1ra (rhIL1ra, anakinra) in severe TBI, at a dose of 100 mg subcutaneously once a day for 5 days in 20 patients randomized 1:1. We provide safety data (primary outcome) in this pathology, utilize cerebral microdialysis to directly determine brain extracellular concentrations of IL1ra and 41 cytokines and chemokines, and use principal component analysis (PCA) to explore the resultant cerebral cytokine profile. Interleukin-1 receptor antagonist was safe, penetrated into plasma and the brain extracellular fluid. The PCA showed a separation in cytokine profiles after IL1ra administration. A candidate cytokine from this analysis, macrophage-derived chemoattractant, was significantly lower in the rhIL1ra-treated group. Our results provide promising data for rhIL1ra as a therapeutic candidate by showing safety, brain penetration and a modification of the neuroinflammatory response to TBI by a putative neuroprotective agent in humans for the first time.

  3. Melanin concentrating hormone receptor 1 (MCHR1) antagonists - Still a viable approach for obesity treatment?

    DEFF Research Database (Denmark)

    Högberg, T.; Frimurer, T.M.; Sasmal, P.K.

    2012-01-01

    Obesity is a global epidemic associated with multiple severe diseases. Several pharmacotherapies have been investigated including the melanin concentrating hormone (MCH) and its receptor 1. The development of MCHR1 antagonists are described with a specific perspective on different chemotypes...

  4. Mineralocorticoid receptor antagonists for heart failure with reduced ejection fraction : integrating evidence into clinical practice

    NARCIS (Netherlands)

    Zannad, Faiez; Stough, Wendy Gattis; Rossignol, Patrick; Bauersachs, Johann; McMurray, John J. V.; Swedberg, Karl; Struthers, Allan D.; Voors, Adriaan A.; Ruilope, Luis M.; Bakris, George L.; O'Connor, Christopher M.; Gheorghiade, Mihai; Mentz, Robert J.; Cohen-Solal, Alain; Maggioni, Aldo P.; Beygui, Farzin; Filippatos, Gerasimos S.; Massy, Ziad A.; Pathak, Atul; Pina, Ileana L.; Sabbah, Hani N.; Sica, Domenic A.; Tavazzi, Luigi; Pitt, Bertram

    2012-01-01

    Mineralocorticoid receptor antagonists (MRAs) improve survival and reduce morbidity in patients with heart failure, reduced ejection fraction (HFREF), and mild-to-severe symptoms, and in patients with left ventricular systolic dysfunction and heart failure after acute myocardial infarction. These

  5. Therapeutic potential of CRF receptor antagonists: a gut-brain perspective.

    Science.gov (United States)

    Heinrichs, S C; Taché, Y

    2001-04-01

    Activation of the corticotropin-releasing factor (CRF) family of neuropeptide receptors in the brain and periphery appears to mediate stress-related changes in a variety of physiological and functional domains. Comparative pharmacology of CRF receptor agonists suggests that CRF, urocortin, sauvagine and urotensin consistently mimic, and conversely peptide CRF receptor antagonists lessen, the functional consequences of stressor exposure. Together with the development of novel non-peptide CRF receptor antagonists, a growing number of CRF receptor selective ligands are available to elucidate the neurobiology and physiological role of CRF systems. The present review considers available preclinical evidence as well as results from one Phase II clinical trial which address the hypothesis that CRF receptor antagonists may represent a new option for pharmacotherapy of stress-related disorders.

  6. Endothelin receptor antagonist and airway dysfunction in pulmonary arterial hypertension

    Directory of Open Access Journals (Sweden)

    Borst Mathias M

    2009-12-01

    Full Text Available Abstract Background In idiopathic pulmonary arterial hypertension (IPAH, peripheral airway obstruction is frequent. This is partially attributed to the mediator dysbalance, particularly an excess of endothelin-1 (ET-1, to increased pulmonary vascular and airway tonus and to local inflammation. Bosentan (ET-1 receptor antagonist improves pulmonary hemodynamics, exercise limitation, and disease severity in IPAH. We hypothesized that bosentan might affect airway obstruction. Methods In 32 IPAH-patients (19 female, WHO functional class II (n = 10, III (n = 22; (data presented as mean ± standard deviation pulmonary vascular resistance (11 ± 5 Wood units, lung function, 6 minute walk test (6-MWT; 364 ± 363.7 (range 179.0-627.0 m, systolic pulmonary artery pressure, sPAP, 79 ± 19 mmHg, and NT-proBNP serum levels (1427 ± 2162.7 (range 59.3-10342.0 ng/L were measured at baseline, after 3 and 12 months of oral bosentan (125 mg twice per day. Results and Discussion At baseline, maximal expiratory flow at 50 and 25% vital capacity were reduced to 65 ± 25 and 45 ± 24% predicted. Total lung capacity was 95.6 ± 12.5% predicted and residual volume was 109 ± 21.4% predicted. During 3 and 12 months of treatment, 6-MWT increased by 32 ± 19 and 53 ± 69 m, respectively; p Conclusion This study gives first evidence in IPAH, that during long-term bosentan, improvement of hemodynamics, functional parameters or serum biomarker occur independently from persisting peripheral airway obstruction.

  7. Update on leukotriene receptor antagonists in preschool children wheezing disorders

    Directory of Open Access Journals (Sweden)

    Montella Silvia

    2012-06-01

    Full Text Available Abstract Asthma is the most common chronic disease in young children. About 40% of all preschool children regularly wheeze during common cold infections. The heterogeneity of wheezing phenotypes early in life and various anatomical and emotional factors unique to young children present significant challenges in the clinical management of this problem. Anti-inflammatory therapy, mainly consisting of inhaled corticosteroids (ICS, is the cornerstone of asthma management. Since Leukotrienes (LTs are chemical mediators of airway inflammation in asthma, the leukotriene receptor antagonists (LTRAs are traditionally used as potent anti-inflammatory drugs in the long-term treatment of asthma in adults, adolescents, and school-age children. In particular, montelukast decreases airway inflammation, and has also a bronchoprotective effect. The main guidelines on asthma management have confirmed the clinical utility of LTRAs in children older than five years. In the present review we describe the most recent advances on the use of LTRAs in the treatment of preschool wheezing disorders. LTRAs are effective in young children with virus-induced wheeze and with multiple-trigger disease. Conflicting data do not allow to reach definitive conclusions on LTRAs efficacy in bronchiolitis or post-bronchiolitis wheeze, and in acute asthma. The excellent safety profile of montelukast and the possibility of oral administration, that entails better compliance from young children, represent the main strengths of its use in preschool children. Montelukast is a valid alternative to ICS especially in poorly compliant preschool children, or in subjects who show adverse effects related to long-term steroid therapy.

  8. Rational design of an auxin antagonist of the SCF(TIR1) auxin receptor complex.

    Science.gov (United States)

    Hayashi, Ken-ichiro; Neve, Joshua; Hirose, Masakazu; Kuboki, Atsuhito; Shimada, Yukihisa; Kepinski, Stefan; Nozaki, Hiroshi

    2012-03-16

    The plant hormone auxin is a master regulator of plant growth and development. By regulating rates of cell division and elongation and triggering specific patterning events, indole 3-acetic acid (IAA) regulates almost every aspect of plant development. The perception of auxin involves the formation of a ternary complex consisting of an F-box protein of the TIR1/AFB family of auxin receptors, the auxin molecule, and a member the Aux/IAA family of co-repressor proteins. In this study, we identified a potent auxin antagonist, α-(phenylethyl-2-oxo)-IAA, as a lead compound for TIR1/AFB receptors by in silico virtual screening. This molecule was used as the basis for the development of a more potent TIR1 antagonist, auxinole (α-[2,4-dimethylphenylethyl-2-oxo]-IAA), using a structure-based drug design approach. Auxinole binds TIR1 to block the formation of the TIR1-IAA-Aux/IAA complex and so inhibits auxin-responsive gene expression. Molecular docking analysis indicates that the phenyl ring in auxinole would strongly interact with Phe82 of TIR1, a residue that is crucial for Aux/IAA recognition. Consistent with this predicted mode of action, auxinole competitively inhibits various auxin responses in planta. Additionally, auxinole blocks auxin responses of the moss Physcomitrella patens, suggesting activity over a broad range of species. Our works not only substantiates the utility of chemical tools for plant biology but also demonstrates a new class of small molecule inhibitor of protein-protein interactions common to mechanisms of perception of other plant hormones, such as jasmonate, gibberellin, and abscisic acid.

  9. The discovery of the benzazepine class of histamine H3 receptor antagonists.

    Science.gov (United States)

    Wilson, David M; Apps, James; Bailey, Nicholas; Bamford, Mark J; Beresford, Isabel J; Briggs, Michael A; Calver, Andrew R; Crook, Barry; Davis, Robert P; Davis, Susannah; Dean, David K; Harris, Leanne; Heightman, Tom D; Panchal, Terry; Parr, Christopher A; Quashie, Nigel; Steadman, Jon G A; Schogger, Joanne; Sehmi, Sanjeet S; Stean, Tania O; Takle, Andrew K; Trail, Brenda K; White, Trevor; Witherington, Jason; Worby, Angela; Medhurst, Andrew D

    2013-12-15

    This Letter describes the discovery of a novel series of H3 receptor antagonists. The initial medicinal chemistry strategy focused on deconstructing and simplifying an early screening hit which rapidly led to the discovery of a novel series of H3 receptor antagonists based on the benzazepine core. Employing an H3 driven pharmacodynamic model, the series was then further optimised through to a lead compound that showed robust in vivo functional activity and possessed overall excellent developability properties.

  10. Preclinical anticonvulsant and neuroprotective profile of 8319, a non-competitive NMDA antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Fielding, S.; Wilker, J.C.; Chernack, J.; Ramirez, V.; Wilmot, C.A.; Martin, L.L.; Payack, J.F.; Cornfeldt, M.L.; Rudolphi, K.A.; Rush, D.K. (Hoechst-Roussel Pharmaceuticals, Inc., Somerville, NJ (USA))

    1990-01-01

    8319, ((+-)-2-Amino-N-ethyl-alpha- (3-methyl-2-thienyl) benzeneethanamine 2HCl), is a novel compound with the profile of a non-competitive NMDA antagonist. The compound displaced (3H) TCP with high affinity (IC50 = 43 nM), but was inactive at the NMDA, benzodiazepine and GABA sites; in vivo, 8319 showed good efficacy as an anticonvulsant and potential neuroprotective agent. It blocked seizures induced by NMDLA, supramaximal electroshock, pentylenetetrazol (PTZ), picrotoxin, and thiosemicarbazide with ED50's of 1-20 mg/kg ip. As a neuroprotective agent, 8319 (30-100 mg/kg sc) prevented the death of dorsal hippocampal pyramidal cells induced by direct injection of 20 nmol NMDA. At 15 mg/kg ip, the compound was also effective against hippocampal neuronal necrosis induced via bilateral occlusion of the carotid arteries in gerbils. In summary, 8319 is a noncompetitive NMDA antagonist with good anticonvulsant activity and may possess neuroprotective properties useful in the treatment of brain ischemia.

  11. Discovery of antagonists of tick dopamine receptors via chemical library screening and comparative pharmacological analyses.

    Science.gov (United States)

    Ejendal, Karin F K; Meyer, Jason M; Brust, Tarsis F; Avramova, Larisa V; Hill, Catherine A; Watts, Val J

    2012-11-01

    Ticks transmit a wide variety of disease causing pathogens to humans and animals. Considering the global health impact of tick-borne diseases, there is a pressing need to develop new methods for vector control. We are exploring arthropod dopamine receptors as novel targets for insecticide/acaricide development because of their integral roles in neurobiology. Herein, we developed a screening assay for dopamine receptor antagonists to further characterize the pharmacological properties of the two D₁-like dopamine receptors (Isdop1 and Isdop2) identified in the Lyme disease vector, Ixodes scapularis, and develop a screening assay for receptor antagonists. A cell-based, cyclic AMP luciferase reporter assay platform was implemented to screen the LOPAC(1280) small molecule library for Isdop2 receptor antagonists, representing the first reported chemical library screen for any tick G protein-coupled receptor. Screening resulted in the identification of 85 "hit" compounds with antagonist activity at the Isdop2 receptor. Eight of these chemistries were selected for confirmation assays using a direct measurement of cAMP, and the effects on both Isdop1 and Isdop2 were studied for comparison. Each of these eight compounds showed antagonistic activity at both Isdop1 and Isdop2, although differences were observed regarding their relative potencies. Furthermore, comparison of the pharmacological properties of the tick dopamine receptors with that of the AaDOP2 receptor from the yellow fever mosquito and the human dopamine D₁ receptor (hD₁) revealed species-specific pharmacological profiles of these receptors. Compounds influencing dopaminergic functioning, such as the dopamine receptor antagonists discovered here, may provide lead chemistries for discovery of novel acaricides useful for vector control

  12. Discovery of 2-substituted benzoxazole carboxamides as 5-HT3 receptor antagonists.

    Science.gov (United States)

    Yang, Zhicai; Fairfax, David J; Maeng, Jun-Ho; Masih, Liaqat; Usyatinsky, Alexander; Hassler, Carla; Isaacson, Soshanna; Fitzpatrick, Kevin; DeOrazio, Russell J; Chen, Jianqing; Harding, James P; Isherwood, Matthew; Dobritsa, Svetlana; Christensen, Kevin L; Wierschke, Jonathan D; Bliss, Brian I; Peterson, Lisa H; Beer, Cathy M; Cioffi, Christopher; Lynch, Michael; Rennells, W Martin; Richards, Justin J; Rust, Timothy; Khmelnitsky, Yuri L; Cohen, Marlene L; Manning, David D

    2010-11-15

    A new class of 2-substituted benzoxazole carboxamides are presented as potent functional 5-HT(3) receptor antagonists. The chemical series possesses nanomolar in vitro activity against human 5-HT(3)A receptors. A chemistry optimization program was conducted and identified 2-aminobenzoxazoles as orally active 5-HT(3) receptor antagonists with good metabolic stability. These novel analogues possess drug-like characteristics and have potential utility for the treatment of diseases attributable to improper 5-HT(3) receptor function, especially diarrhea predominant irritable bowel syndrome (IBS-D).

  13. Design, synthesis, and pharmacological characterization of novel, potent NMDA receptor antagonists

    DEFF Research Database (Denmark)

    Conti, Paola; De Amici, Marco; Grazioso, Giovanni

    2004-01-01

    acids were tested at ionotropic and metabotropic glutamate receptors. None of the compounds was active, neither as agonists nor as antagonists, at 1 mM on metabotropic receptors (mGluR1, -2, -4, and -5 expressed in CHO cell lines). Conversely, the pair of stereoisomers 8A/8B showed a remarkable affinity......, antagonist potency, and selectivity for NMDA receptors, when tested on ionotropic glutamate receptors. The affinity of 8A proved to be 5 times higher than that of diastereomer 8B (K(i) values 0.21 and 0.96 microM, respectively). Furthermore, compounds 8A and 8B exhibited a noteworthy anticonvulsant activity...

  14. Effect of ghrelin receptor antagonist on meal patterns in cholecystokinin type 1 receptor null mice.

    Science.gov (United States)

    Lee, Jennifer; Martin, Elizabeth; Paulino, Gabriel; de Lartigue, Guillaume; Raybould, Helen E

    2011-05-03

    Vagal afferent neurons (VAN) express the cholecystokinin (CCK) type 1 receptor (CCK₁R) and, as predicted by the role of CCK in inducing satiation, CCK₁R⁻/⁻ mice ingest larger and longer meals. However, after a short fast, CCK₁R⁻/⁻ mice ingesting high fat (HF) diets initiate feeding earlier than wild-type mice. We hypothesized that the increased drive to eat in CCK₁R⁻/⁻ mice eating HF diet is mediated by ghrelin, a gut peptide that stimulates food intake. The decrease in time to first meal, and the increase in meal size and duration in CCK₁R⁻/⁻ compared to wild-type mice ingesting high fat (HF) diet were reversed by administration of GHSR1a antagonist D-(Lys3)-GHRP-6 (p<0.05). Administration of the GHSR1a antagonist significantly increased expression of the neuropeptide cocaine and amphetamine-regulated transcript (CART) in VAN of HF-fed CCK₁R⁻/⁻ but not wild-type mice. Administration of the GHSR1a antagonist decreased neuronal activity measured by immunoreactivity for fos protein in the nucleus of the solitary tract (NTS) and the arcuate nucleus of both HF-fed wild-type and CCK₁R⁻/⁻ mice. The data show that hyperphagia in CCK₁R⁻/⁻ mice ingesting HF diet is reversed by blockade of the ghrelin receptor, suggesting that in the absence of the CCK₁R, there is an increased ghrelin-dependent drive to feed. The site of action of ghrelin receptors is unclear, but may involve an increase in expression of CART peptide in VAN in HF-fed CCK₁R⁻/⁻ mice.

  15. [Comparative pharmacophore analysis of dual dopamine D2/5-HT(2A) receptor antagonists].

    Science.gov (United States)

    Guo, Yan-shen; Guo, Zong-ru

    2009-03-01

    Dual dopamine D2/5-HT2A receptor antagonists have potent activity and are referred to atypical antipsychotics due to their lower propensity to elicit EPS and their moderate efficacy toward negative symptoms. However, an on-going challenge in developing atypical antipsychotics drugs is to maintain the favorable profiles and avoid of cardiovascular risk. In this paper, comparative pharmacophore analysis of dual dopamine D2/5-HT2A receptor antagonists, hERG K+ channel blockers, and alA adrenoceptor antagonists is carried out, and the results could give some insight into multi-target drug design.

  16. A new pyrrolyl-quinoxalinedione series of non-NMDA glutamate receptor antagonists: pharmacological characterization and comparison with NBQX and valproate in the kindling model of epilepsy.

    Science.gov (United States)

    Löscher, W; Lehmann, H; Behl, B; Seemann, D; Teschendorf, H J; Hofmann, H P; Lubisch, W; Höger, T; Lemaire, H G; Gross, G

    1999-01-01

    Antagonists at the ionotropic non-NMDA [AMPA (amino-methyl proprionic acid)/kainate] type of glutamate receptors have been suggested to possess several advantages compared to NMDA (N-methyl-D-aspartate) receptor antagonists, particularly in terms of risk/benefit ratio, but the non-NMDA receptor antagonists available so far have not fulfilled this promise. From a large series of pyrrolyl-quinoxalinedione derivatives, we selected six new competitive non-NMDA receptor antagonists. The basis of selection was high potency and selectivity for AMPA and/or kainate receptors, high in vivo potency after systemic administration, and an acceptable ratio between neuroprotective or anticonvulsant effects and adverse effects. Pharmacological characteristics of these novel compounds are described in this study with special emphasis on their effects in the kindling model of temporal lobe epilepsy, the most common type of epilepsy in humans. In most experiments, NBQX and the major antiepileptic drug valproate were used for comparison with the novel compounds. The novel non-NMDA receptor antagonists markedly differed in their AMPA and kainate receptor affinities from NBQX. Thus, while NBQX essentially did not bind to kainate receptors at relevant concentrations, several of the novel compounds exhibited affinity to rat brain kainate receptors or recombinant kainate receptor subtypes in addition to AMPA receptors. One compound, LU 97175, bound to native high affinity kainate receptors and rat GluR5-GluR7 subunits, i.e. low affinity kainate binding sites, with much higher affinities than to AMPA receptors. All compounds potently blocked AMPA-induced cell death in vitro and, except LU 97175, AMPA-induced convulsions in vivo. In the kindling model, compounds with a high affinity for GluR7 (LU 97175) or compounds (LU 115455, LU 136541) which potently bind to AMPA receptors and low affinity kainate receptor subunits were potent anticonvulsants in the kindling model, whereas the AMPA

  17. Haplotypes of the interleukin-1 receptor antagonist gene, interleukin-1 receptor antagonist mRNA levels and the risk of myocardial infarction

    NARCIS (Netherlands)

    van Minkelen, Rick; Wettinger, Stephanie Bezzina; de Visser, Marieke C.H.; Vos, Hans L.; Reitsma, Pieter H.; Rosendaal, Frits R.; Bertina, Rogier M.; Doggen, Catharina Jacoba Maria

    2009-01-01

    Background The overall effect of the major pro-inflammatory cytokine interleukin-1 (IL-1) on coagulation and fibrinolysis is prothrombotic. We recently found that haplotype 5 (H5) of the gene (IL1RN) coding for the interleukin-1 receptor antagonist (IL-1Ra), the natural inhibitor of IL-1, is

  18. Investigation of the binding and functional properties of extended length D3 dopamine receptor-selective antagonists.

    Science.gov (United States)

    Furman, Cheryse A; Roof, Rebecca A; Moritz, Amy E; Miller, Brittney N; Doyle, Trevor B; Free, R Benjamin; Banala, Ashwini K; Paul, Noel M; Kumar, Vivek; Sibley, Christopher D; Newman, Amy Hauck; Sibley, David R

    2015-09-01

    The D3 dopamine receptor represents an important target in drug addiction in that reducing receptor activity may attenuate the self-administration of drugs and/or disrupt drug or cue-induced relapse. Medicinal chemistry efforts have led to the development of D3 preferring antagonists and partial agonists that are >100-fold selective vs. the closely related D2 receptor, as best exemplified by extended-length 4-phenylpiperazine derivatives. Based on the D3 receptor crystal structure, these molecules are known to dock to two sites on the receptor where the 4-phenylpiperazine moiety binds to the orthosteric site and an extended aryl amide moiety docks to a secondary binding pocket. The bivalent nature of the receptor binding of these compounds is believed to contribute to their D3 selectivity. In this study, we examined if such compounds might also be "bitopic" such that their aryl amide moieties act as allosteric modulators to further enhance the affinities of the full-length molecules for the receptor. First, we deconstructed several extended-length D3-selective ligands into fragments, termed "synthons", representing either orthosteric or secondary aryl amide pharmacophores and investigated their effects on D3 receptor binding and function. The orthosteric synthons were found to inhibit radioligand binding and to antagonize dopamine activation of the D3 receptor, albeit with lower affinities than the full-length compounds. Notably, the aryl amide-based synthons had no effect on the affinities or potencies of the orthosteric synthons, nor did they have any effect on receptor activation by dopamine. Additionally, pharmacological investigation of the full-length D3-selective antagonists revealed that these compounds interacted with the D3 receptor in a purely competitive manner. Our data further support that the 4-phenylpiperazine D3-selective antagonists are bivalent and that their enhanced affinity for the D3 receptor is due to binding at both the orthosteric site as

  19. Low doses of the NMDA receptor antagonists, MK-801, PEAQX, and ifenprodil, induces social facilitation in adolescent male rats.

    Science.gov (United States)

    Morales, Melissa; Varlinskaya, Elena I; Spear, Linda P

    2013-08-01

    Adolescents display high levels of interactions with peers relative to other age groups, with these interactions further enhanced by ethanol under some circumstances. Understanding of the neural mechanisms underlying these high levels of social interactions is important given that alcohol use is initiated during adolescence and adolescents tend to report drinking for social reasons. Given that ethanol's effects are associated in part with functional antagonism of the NMDA receptor system, the current experiment explored the role of NMDA antagonists for facilitating adolescent social behavior. Adolescent male Sprague-Dawley rats were challenged acutely with either the non-competitive NMDA antagonist, MK-801 (0.01, 0.03mg/kg), the NR2A antagonist, PEAQX (1.25, 3.75mg/kg) or the NR2B antagonist, ifenprodil (0.75, 2.25mg/kg) 30min prior to a 10-min social interaction test. All compounds generally increased overall social activity (i.e., sum of social investigation, contact behavior, and play), with ifenprodil also significantly enhancing play and social contact behaviors. Although the frequencies of peer-directed social behaviors were typically greater following administration with these NMDA antagonists, social preference, indexed via the number of crossovers to the side with the partner relative to crossovers away, was significantly reduced in MK-801 and PEAQX-treated rats. None of these changes were associated with concomitant alterations in overall locomotor activity under these test circumstances. These data support the suggestion that the increases in social interactions observed in adolescents following acute ethanol may be driven in part by NMDA receptor antagonism - particularly of the NR2B subunit - given that ifenprodil stimulated social behavior in a manner similar to that produced by low doses of ethanol. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. 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 t...

  1. No effect of angiotensin II AT(2)-receptor antagonist PD 123319 on cerebral blood flow autoregulation

    DEFF Research Database (Denmark)

    Estrup, T M; Paulson, O B; Strandgaard, S

    2001-01-01

    Blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin AT1-receptor antagonists shift the limits of autoregulation of cerebral blood flow (CBF) towards lower blood pressure (BP). The role of AT2-receptors in the regulation of the cerebral cir...

  2. Montelukast, a leukotriene receptor antagonist, modulates lung CysLT1

    Institute of Scientific and Technical Information of China (English)

    ZHANGYan-Jun; ZHANGLei; WANGShao-Bin; SHENHua-Hao; WEIEr-Qing

    2004-01-01

    AIM: To determine the expressions of cysteinyl leukotriene receptors, CysLT, and CysLT2 , in airway eosinophilic inflammation of OVA-induced asthmatic mice and the modulation by montelukast, a CysLT1 receptor antagonist. METHODS: Asthma model was induced by chronic exposure to ovalbumin (OVA) in C57BL/6 mice. The eosinophils in

  3. Pyrrolidin-3-yl-N-methylbenzamides as potent histamine 3 receptor antagonists.

    Science.gov (United States)

    Zhou, Dahui; Gross, Jonathan L; Sze, Jean Y; Adedoyin, Adedayo B; Bowlby, Mark; Di, Li; Platt, Brian J; Zhang, Guoming; Brandon, Nicholas; Comery, Thomas A; Robichaud, Albert J

    2011-10-01

    On the basis of the previously reported benzimidazole 1,3'-bipyrrolidine benzamides (1), a series of related pyrrolidin-3-yl-N-methylbenzamides were synthesized and evaluated as H(3) receptor antagonists. In particular, compound 32 exhibits potent H(3) receptor binding affinity, improved pharmaceutical properties and a favorable in vivo profile.

  4. Bicyclic and tricyclic heterocycle derivatives as histamine H3 receptor antagonists for the treatment of obesity.

    Science.gov (United States)

    de Lera Ruiz, Manuel; Zheng, Junying; Berlin, Michael Y; McCormick, Kevin D; Aslanian, Robert G; West, Robert; Hwa, Joyce; Lachowicz, Jean; van Heek, Margaret

    2013-11-01

    A novel series of non-imidazole bicyclic and tricyclic histamine H3 receptor antagonists has been discovered. Compound 17 was identified as a centrally penetrant molecule with high receptor occupancy which demonstrates robust oral activity in rodent models of obesity. In addition compound 17 possesses clean CYP and hERG profiles and shows no behavioral changes in the Irwin test.

  5. No effect of angiotensin II AT(2)-receptor antagonist PD 123319 on cerebral blood flow autoregulation

    DEFF Research Database (Denmark)

    Estrup, T M; Paulson, O B; Strandgaard, S

    2001-01-01

    Blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin AT1-receptor antagonists shift the limits of autoregulation of cerebral blood flow (CBF) towards lower blood pressure (BP). The role of AT2-receptors in the regulation of the cerebral...

  6. Computer-aided molecular modeling of a thromboxane receptor antagonist S-145 and its related compounds.

    Science.gov (United States)

    Ezumi, K; Yamakawa, M; Narisada, M

    1990-04-01

    Conformational analyses on thromboxane A2 (TxA2), its receptor agonist, U-46619, and its receptor antagonist, sulotroban, were carried out by molecular mechanics (MMFF) or molecular orbital (MNDO) methods. Two kinds of putative active conformations of TxA2 and the agonist were proposed on the basis of these results by referring to the hairpin conformation hypothesis. From the superposition of stable conformers of sulotroban on those conformers, the molecular structural requirements for potent TxA2 receptor antagonism were elucidated. S-145 in which these requirements are satisfied was a very potent TxA2 antagonist.

  7. Chemogenomic discovery of allosteric antagonists at the GPRC6A receptor

    DEFF Research Database (Denmark)

    Gloriam, David E.; Wellendorph, Petrine; Johansen, Lars Dan

    2011-01-01

     pharmacological activity across GPCR families provides proof-of-concept for in silico approaches against Family C targets based on Family A templates, greatly expanding the prospects of successful drug design and discovery. The antagonists were tested against a panel of seven Family A and C G protein-coupled receptors......, calindol and NPS 2143, which both display ~30-fold selectivity for the calcium-sensing receptor compared to GPRC6A. The antagonists constitute novel research tools toward investigating the signaling mechanism of the GPRC6A receptor at the cellular level and serve as initial ligands for further optimization...

  8. Synthesis and Biological Evaluation of Substituted Desloratadines as Potent Arginine Vasopressin V2 Receptor Antagonists

    Directory of Open Access Journals (Sweden)

    Shuai Mu

    2014-02-01

    Full Text Available Twenty-one non-peptide substituted desloratadine class compounds were synthesized as novel arginine vasopressin receptor antagonists from desloratadine via successive acylation, reduction and acylation reactions. Their structures were characterized by 1H-NMR and HRMS, their biological activity was evaluated by in vitro and in vivo studies. The in vitro binding assay and cAMP accumulation assay indicated that these compounds are potent selective V2 receptor antagonists. Among them compounds 1n, 1t and 1v exhibited both high affinity and promising selectivity for V2 receptors. The in vivo diuretic assay demonstrated that 1t presented remarkable diuretic activity. In conclusion, 1t is a potent novel AVP V2 receptor antagonist candidate.

  9. Anti free radical action of calcium antagonists and H1 and H2 receptors antagonists in neoplastic disease.

    Science.gov (United States)

    della Rovere, F; Broccio, M; Granata, A; Zirilli, A; Brugnano, L; Artemisia, A; Broccio, G

    1996-01-01

    The blood of the subjects suffering from Neoplastic Disease (ND) shows phenomena of membrane peroxidation due to the presence of Free Radicals (FRs), in a quantity much greater than the one observed in the blood of healthy subjects. This can be detected either by calculating the time necessary for the formation of "Heinz bodies" (Hbs), (p < 0.00001) after oxidative stress of the blood in vitro with acetylphenylidrazine (APH), or by calculating the methemoglobin (metHb) quantity that forms after the same treatment (P < 0.00001). The statistical analyses we carried out showed that metHb formation was not affected by age, sex, smoking habits, red blood cell number, Hb, Ht or tumor staging. In this study, by using equal parameters of investigation, we noted that the blood of the subjects with ND who were previously treated with calcium-antagonists drugs and with antagonists of H1 and H2 receptors, gave results completely superimposable on the results obtained from healthy subjects, implying that the treatment had avoided the increase of FRs. Therefore we concluded that calcium-antagonists and the antagonists of the H1 and H2 receptors behave as antioxidant substances, having decreased the FRs damaging activity on the cellular membranes, thus controlling, although to a limited degree, the pejorative evolution of the disease. It is also important to remember that investigations into the ND, even possible screenings, must take into account the above said data, submitting the subjects under investigation to a pharmacological wash out, particularly with those substances which, are considered to be scavengers of FRs. Some of these substances are investigated in this work.

  10. THE INTERACTION OF SELECTIVE AND NONSELECTIVE ANTAGONISTS WITH PREJUNCTIONAL AND POSTJUNCTIONAL MUSCARINIC RECEPTOR SUBTYPES IN THE GUINEA-PIG TRACHEA

    NARCIS (Netherlands)

    TENBERGE, REJ; ROFFEL, AF; ZAAGSMA, J

    1993-01-01

    Muscarinic receptor antagonists were used to study prejunctional M2 and postjunctional M3 receptors in the isolated guinea pig trachea. The effects of four M2-selective muscarinic receptor antagonists (gallamine, methoctramine, AQ-RA 741 and AF-DX 116) were studied on twitch contractions, elicited

  11. THE INTERACTION OF SELECTIVE AND NONSELECTIVE ANTAGONISTS WITH PREJUNCTIONAL AND POSTJUNCTIONAL MUSCARINIC RECEPTOR SUBTYPES IN THE GUINEA-PIG TRACHEA

    NARCIS (Netherlands)

    TENBERGE, REJ; ROFFEL, AF; ZAAGSMA, J

    1993-01-01

    Muscarinic receptor antagonists were used to study prejunctional M2 and postjunctional M3 receptors in the isolated guinea pig trachea. The effects of four M2-selective muscarinic receptor antagonists (gallamine, methoctramine, AQ-RA 741 and AF-DX 116) were studied on twitch contractions, elicited b

  12. 5-HT2B Receptor Antagonists Inhibit Fibrosis and Protect from RV Heart Failure

    Directory of Open Access Journals (Sweden)

    Wiebke Janssen

    2015-01-01

    Full Text Available Objective. The serotonin (5-HT pathway was shown to play a role in pulmonary hypertension (PH, but its functions in right ventricular failure (RVF remain poorly understood. The aim of the current study was to investigate the effects of Terguride (5-HT2A and 2B receptor antagonist or SB204741 (5-HT2B receptor antagonist on right heart function and structure upon pulmonary artery banding (PAB in mice. Methods. Seven days after PAB, mice were treated for 14 days with Terguride (0.2 mg/kg bid or SB204741 (5 mg/kg day. Right heart function and remodeling were assessed by right heart catheterization, magnetic resonance imaging (MRI, and histomorphometric methods. Total secreted collagen content was determined in mouse cardiac fibroblasts isolated from RV tissues. Results. Chronic treatment with Terguride or SB204741 reduced right ventricular fibrosis and showed improved heart function in mice after PAB. Moreover, 5-HT2B receptor antagonists diminished TGF-beta1 induced collagen synthesis of RV cardiac fibroblasts in vitro. Conclusion. 5-HT2B receptor antagonists reduce collagen deposition, thereby inhibiting right ventricular fibrosis. Chronic treatment prevented the development and progression of pressure overload-induced RVF in mice. Thus, 5-HT2B receptor antagonists represent a valuable novel therapeutic approach for RVF.

  13. 5-HT2B receptor antagonists inhibit fibrosis and protect from RV heart failure.

    Science.gov (United States)

    Janssen, Wiebke; Schymura, Yves; Novoyatleva, Tatyana; Kojonazarov, Baktybek; Boehm, Mario; Wietelmann, Astrid; Luitel, Himal; Murmann, Kirsten; Krompiec, Damian Richard; Tretyn, Aleksandra; Pullamsetti, Soni Savai; Weissmann, Norbert; Seeger, Werner; Ghofrani, Hossein Ardeschir; Schermuly, Ralph Theo

    2015-01-01

    The serotonin (5-HT) pathway was shown to play a role in pulmonary hypertension (PH), but its functions in right ventricular failure (RVF) remain poorly understood. The aim of the current study was to investigate the effects of Terguride (5-HT2A and 2B receptor antagonist) or SB204741 (5-HT2B receptor antagonist) on right heart function and structure upon pulmonary artery banding (PAB) in mice. Seven days after PAB, mice were treated for 14 days with Terguride (0.2 mg/kg bid) or SB204741 (5 mg/kg day). Right heart function and remodeling were assessed by right heart catheterization, magnetic resonance imaging (MRI), and histomorphometric methods. Total secreted collagen content was determined in mouse cardiac fibroblasts isolated from RV tissues. Chronic treatment with Terguride or SB204741 reduced right ventricular fibrosis and showed improved heart function in mice after PAB. Moreover, 5-HT2B receptor antagonists diminished TGF-beta1 induced collagen synthesis of RV cardiac fibroblasts in vitro. 5-HT2B receptor antagonists reduce collagen deposition, thereby inhibiting right ventricular fibrosis. Chronic treatment prevented the development and progression of pressure overload-induced RVF in mice. Thus, 5-HT2B receptor antagonists represent a valuable novel therapeutic approach for RVF.

  14. Muscarinic receptor antagonists, from folklore to pharmacology; finding drugs that actually work in asthma and COPD.

    Science.gov (United States)

    Moulton, Bart C; Fryer, Allison D

    2011-05-01

    In the lungs, parasympathetic nerves provide the dominant control of airway smooth muscle with release of acetylcholine onto M3 muscarinic receptors. Treatment of airway disease with anticholinergic drugs that block muscarinic receptors began over 2000 years ago. Pharmacologic data all indicated that antimuscarinic drugs should be highly effective in asthma but clinical results were mixed. Thus, with the discovery of effective β-adrenergic receptor agonists the use of muscarinic antagonists declined. Lack of effectiveness of muscarinic antagonists is due to a variety of factors including unwanted side effects (ranging from dry mouth to coma) and the discovery of additional muscarinic receptor subtypes in the lungs with sometimes competing effects. Perhaps the most important problem is ineffective dosing due to poorly understood differences between routes of administration and no effective way of testing whether antagonists block receptors stimulated physiologically by acetylcholine. Newer muscarinic receptor antagonists are being developed that address the problems of side effects and receptor selectivity that appear to be quite promising in the treatment of asthma and chronic obstructive pulmonary disease.

  15. Intrathecal injection of glutamate receptor antagonists/agonist selectively attenuated rat pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch.

    Science.gov (United States)

    Liu, Tong; Pang, Xue-Yan; Bai, Zhan-Tao; Chai, Zhi-Fang; Jiang, Feng; Ji, Yong-Hua

    2007-12-15

    The present study investigated the involvement of spinal glutamate receptors in the induction and maintenance of the pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch (BmK). (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5-10-imine hydrogen maleate (MK-801; 40nmol; a non-competitive NMDA receptor antagonist), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 40nmol; a non-NMDA receptor antagonist), dl-amino-3-phosphonopropionic acid (dl-AP3; 100nmol; a group I metabotropic glutamate receptor antagonist) and 4-aminopyrrolidine-2,4-dicarboxylate (APDC; 100nmol; a group II metabotropic glutamate receptor agonist) were employed. On intrathecal injection of glutamate receptor antagonists/agonist before BmK venom administration by 10min, BmK venom-induced spontaneous nociceptive responses could be suppressed by all tested agents. Primary thermal hyperalgesia could be inhibited by MK-801 and dl-AP3, while bilateral mechanical hyperalgesia could be inhibited by CNQX and dl-AP3 and contralateral mechanical hyperalgesia could be inhibited by APDC. On intrathecal injection of glutamate receptor antagonists/agonist after BmK venom injection by 4.5h, primary thermal hyperalgesia could be partially reversed by all tested agents, while bilateral mechanical hyperalgesia could only be inhibited by APDC. The results suggest that the role of spinal glutamate receptors may be different on the various manifestations of BmK venom-induced pain-related behaviors.

  16. Predictions of in vivo prolactin levels from in vitro k I values of d 2 receptor antagonists using an agonist-antagonist interaction model

    NARCIS (Netherlands)

    Petersson, K.J.; Vermeulen, A.M.J.; Friberg, L.E.

    2013-01-01

    Prolactin elevation is a side effect of all currently available D2 receptor antagonists used in the treatment of schizophrenia. Prolactin elevation is the result of a direct antagonistic D2 effect blocking the tonic inhibition of prolactin release by dopamine. The aims of this work were to assess th

  17. New competition assay for the solubilized hepatic galactosyl receptor

    Energy Technology Data Exchange (ETDEWEB)

    Ray, D.A.; Weigel, P.H.

    1985-02-15

    The present method of quantitating soluble asialoglycoprotein (galactosyl) receptor activity relies on the selective precipitation of receptor-ligand complexes to allow separation from free ligand. To provide an alternative to selective precipitation procedures, a simple and rapid method to assay for detergent-solubilized galactosyl receptor activity has been developed which uses permeabilized, fixed cells as a source of immobilized solid-phase receptors. Isolated rat hepatocytes were treated with digitonin to make available the internal as well as the external receptors. The permeable cells were also treated with glutaraldehyde to prevent further protein loss during subsequent exposure to detergents such as Triton X-100. The permeable/fixed cells, which retained about 70% of their total /sup 125/I-asialo-orosomucoid (/sup 125/I-ASOR)-binding activity, with 89% specific binding, were insoluble even in 0.5% Triton X-100 and were easily pelleted. The permeable/fixed cells can be prepared in advance and stored frozen for months. A detergent extract of receptor is mixed with a constant amount of both /sup 125/I-ASOR and permeable/fixed cells. Soluble active receptors compete with immobilized receptors on the treated cell for binding of the /sup 125/I-ASOR. The assay is reproducible, linear over a broad range of soluble receptor concentration, and can quantitate receptor activity from as few as 10(5) hepatocytes. A modified purification procedure for the rat hepatic galactosyl receptor using this competition assay is also described.

  18. Effects of H1–receptor antagonists in antidepressant tests in rats

    OpenAIRE

    Chitra C. Khanwelkar

    2008-01-01

    : Considering the vast data suggesting the role of brain histamine(HA) in behaviour,emotions,anxiety and depression;four H1-receptor antagonists; promethazine, diphenhydramine, cyclizine and pheniramine were subjected to antidepressant tests in rats. All H1 – antagonists behaved like antidepressants in animal tests. They antagonized reserpine induced catalepsy, potentiated methamphetamine induced stereotypy and reduced the period of immobility in Porsolt’s behavioural despair test. It is sug...

  19. Neurokinin-1 receptor antagonists as antitumor drugs in gastrointestinal cancer: A new approach

    Directory of Open Access Journals (Sweden)

    Miguel Muñoz

    2016-01-01

    Full Text Available Gastrointestinal (GI cancer is the term for a group of cancers affecting the digestive system. After binding to the neurokinin-1 (NK-1 receptor, the undecapeptide substance P (SP regulates GI cancer cell proliferation and migration for invasion and metastasis, and controls endothelial cell proliferation for angiogenesis. SP also exerts an antiapoptotic effect. Both SP and the NK-1 receptor are located in GI tumor cells, the NK-1 receptor being overexpressed. By contrast, after binding to the NK-1 receptor, NK-1 receptor antagonists elicit the inhibition (epidermal growth factor receptor inhibition of the proliferation of GI cancer cells in a concentration-dependent manner, induce the death of GI cancer cells by apoptosis, counteract the Warburg effect, inhibit cancer cell migration (counteracting invasion and metastasis, and inhibit angiogenesis (vascular endothelial growth factor inhibition. NK-1 receptor antagonists are safe and well tolerated. Thus, the NK-1 receptor could be considered as a new target in GI cancer and NK-1 receptor antagonists (eg, aprepitant could be a new promising approach for the treatment of GI cancer.

  20. Optimizing subcutaneous injection of the gonadotropin-releasing hormone receptor antagonist degarelix.

    Science.gov (United States)

    Barkin, Jack; Burton, Shelley; Lambert, Carole

    2016-02-01

    The gonadotropin-releasing hormone (GnRH) receptor antagonist degarelix has several unique characteristics compared to luteinizing hormone-releasing hormone (LHRH) analogs used in the management of prostate cancer. Notable differences of GnRH receptor antagonists include no flare reaction, and a more rapid suppression of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and prostate-specific antigen (PSA) compared to LHRH analogs. Despite emerging evidence supporting the use of GnRH receptor antagonists over the more widely used LHRH analogs in the management of prostate cancer, physicians may be reluctant to prescribe degarelix. They may be concerned about patient complaints about injection-site reactions (ISRs). The subcutaneous injection of degarelix has been associated with a higher rate of ISRs compared with the intramuscular injections of LHRH analogs. This "How I Do It" article describes techniques and strategies that have been developed by physicians and nurses to reduce the discomfort associated with the subcutaneous delivery of degarelix.

  1. Orexin 1 receptor antagonists in compulsive behaviour and anxiety: possible therapeutic use.

    Directory of Open Access Journals (Sweden)

    Emilio eMerlo-Pich

    2014-02-01

    Full Text Available Fifteen years after the discovery of hypocretin/orexin a large body of evidence has been collected supporting its critical role in the modulation of several regulatory physiological functions. While reduced levels of hypocretin/orexin were early on associated with narcolepsy, increased levels have been linked in recent years to pathological states of hypervigilance and, in particular, to insomnia. The filing to FDA of the dual-activity orexin receptor antagonist (DORA suvorexant for the indication of insomnia further corroborates the robustness of such evidences. However, as excessive vigilance is also typical of anxiety and panic episodes, as well as of abstinence and craving in substance misuse disorders, in this review we briefly discuss the evidence supporting the development of hypocretin/orexin receptor 1 (OX1 antagonists for these indications. Experiments using the OX1 antagonist SB-334867 and mutant mice have involved the OX1 receptor in mediating the compulsive reinstatement of drug seeking for ethanol, nicotine, cocaine, cannabinoids and morphine. More recently, data have been generated with the novel selective OX1 antagonists GSK1059865 and ACT-335827 on behavioural and cardiovascular response to stressors and panic-inducing agents in animals. Concluding, while waiting for pharmacologic data to become available in humans, risks and benefits for the development of an OX1 receptor antagonist for Binge Eating and Anxiety Disorders are discussed.

  2. Optimization of ketone-based P2Y(12) receptor antagonists as antithrombotic agents: pharmacodynamics and receptor kinetics considerations.

    Science.gov (United States)

    Giordanetto, Fabrizio; Bach, Peter; Zetterberg, Fredrik; Antonsson, Thomas; Bylund, Ruth; Johansson, Johan; Sellén, Mikael; Brown, David; Hideståhl, Lotta; Berntsson, Pia; Hovdal, Daniel; Zachrisson, Helen; Björkman, Jan-Arne; van Giezen, J J J

    2014-07-01

    Modification of a series of P2Y12 receptor antagonists by replacement of the ester functionality was aimed at minimizing the risk of in vivo metabolic instability and pharmacokinetic variability. The resulting ketones were then optimized for their P2Y12 antagonistic and anticoagulation effects in combination with their physicochemical and absorption profiles. The most promising compound showed very potent antiplatelet action in vivo. However, pharmacodynamic-pharmacokinetic analysis did not reveal a significant separation between its anti-platelet and bleeding effects. The relevance of receptor binding kinetics to the in vivo profile is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Benzodiazepine receptor antagonists for acute and chronic hepatic encephalopathy

    DEFF Research Database (Denmark)

    Als-Nielsen, B; Kjaergard, L L; Gluud, C

    2001-01-01

    The pathogenesis of hepatic encephalopathy is unknown. It has been suggested that liver failure leads to the accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition which may progress to coma. Several trials have assessed benzodiazepine receptor...

  4. Antagonists of the human A(2A) receptor. Part 6: Further optimization of pyrimidine-4-carboxamides.

    Science.gov (United States)

    Gillespie, Roger J; Bamford, Samantha J; Clay, Alex; Gaur, Suneel; Haymes, Tim; Jackson, Philip S; Jordan, Allan M; Klenke, Burkhard; Leonardi, Stefania; Liu, Jeanette; Mansell, Howard L; Ng, Sean; Saadi, Mona; Simmonite, Heather; Stratton, Gemma C; Todd, Richard S; Williamson, Douglas S; Yule, Ian A

    2009-09-15

    Antagonists of the human A(2A) receptor have been reported to have potential therapeutic benefit in the alleviation of the symptoms associated with neurodegenerative movement disorders such as Parkinson's disease. As part of our efforts to discover potent and selective antagonists of this receptor, we herein describe the detailed optimization and structure-activity relationships of a series of pyrimidine-4-carboxamides. These optimized derivatives display desirable physiochemical and pharmacokinetic profiles, which have led to promising oral activity in clinically relevant models of Parkinson's disease.

  5. 5-HT2B Receptor Antagonists Inhibit Fibrosis and Protect from RV Heart Failure

    OpenAIRE

    Wiebke Janssen; Yves Schymura; Tatyana Novoyatleva; Baktybek Kojonazarov; Mario Boehm; Astrid Wietelmann; Himal Luitel; Kirsten Murmann; Damian Richard Krompiec; Aleksandra Tretyn; Soni Savai Pullamsetti; Norbert Weissmann; Werner Seeger; Hossein Ardeschir Ghofrani; Ralph Theo Schermuly

    2015-01-01

    Objective. The serotonin (5-HT) pathway was shown to play a role in pulmonary hypertension (PH), but its functions in right ventricular failure (RVF) remain poorly understood. The aim of the current study was to investigate the effects of Terguride (5-HT2A and 2B receptor antagonist) or SB204741 (5-HT2B receptor antagonist) on right heart function and structure upon pulmonary artery banding (PAB) in mice. Methods. Seven days after PAB, mice were treated for 14 days with Terguride (0.2 mg/kg b...

  6. Development of a human vasopressin V1a-receptor antagonist from an evolutionary-related insect neuropeptide

    Science.gov (United States)

    di Giglio, Maria Giulia; Muttenthaler, Markus; Harpsøe, Kasper; Liutkeviciute, Zita; Keov, Peter; Eder, Thomas; Rattei, Thomas; Arrowsmith, Sarah; Wray, Susan; Marek, Ales; Elbert, Tomas; Alewood, Paul F.; Gloriam, David E.; Gruber, Christian W.

    2017-02-01

    Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the insect oxytocin/vasopressin orthologue inotocin from the black garden ant (Lasius niger), identified and cloned its cognate receptor and determined its pharmacological properties on the insect and human oxytocin/vasopressin receptors. Subsequently, we identified a functional dichotomy: inotocin activated the insect inotocin and the human vasopressin V1b receptors, but inhibited the human V1aR. Replacement of Arg8 of inotocin by D-Arg8 led to a potent, stable and competitive V1aR-antagonist ([D-Arg8]-inotocin) with a 3,000-fold binding selectivity for the human V1aR over the other three subtypes, OTR, V1bR and V2R. The Arg8/D-Arg8 ligand-pair was further investigated to gain novel insights into the oxytocin/vasopressin peptide-receptor interaction, which led to the identification of key residues of the receptors that are important for ligand functionality and selectivity. These observations could play an important role for development of oxytocin/vasopressin receptor modulators that would enable clear distinction of the physiological and pathological responses of the individual receptor subtypes.

  7. SB-258741: a 5-HT7 receptor antagonist of potential clinical interest.

    Science.gov (United States)

    Pouzet, Bruno

    2002-01-01

    Recently, a series of 5-HT7 receptor antagonists have been developed (24,29,36,68). Among them SB-258741, R-(+)-1-(toluene-3-sulfonyl)-2-[2-(4-methylpiperidin-1-yl)ethyl]-pyrrolidine, (compound "13" in 36,37) was one of the most potent and specific compounds. Due to a lack of specific ligands the pharmacology of 5-HT7 receptor antagonists is still relatively unexplored. It has been suggested, however, that 5-HT7 receptor ligands could be useful in the therapy of various disorders such as sleep disorders, schizophrenia, depression, migraine, epilepsy, pain, or memory impairment. Many of these conceivable indications are not supported by pharmacological data. It is, therefore, of particular interest to review the data generated from studies of one of these most potent and specific 5-HT7 receptor antagonists, SB-258741, with a goal of testing the validity of the proposed clinical indications. In this review, the author describes pharmacology of this compound in order to define its potential clinical use. The available safety pharmacology data are discussed in an attempt to predict potential side effects of specific 5-HT7 receptor antagonists.

  8. The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy.

    Science.gov (United States)

    Sato, Atsuhisa

    2015-06-01

    Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.

  9. At last, a truly selective EP2 receptor antagonist

    OpenAIRE

    Birrell, Mark A.; Nials, Anthony T.

    2011-01-01

    Ever since the discovery of prostaglandin E2 (PGE2), this lipid mediator has been the focus of intense research. The diverse biological effects of PGE2 are due, at least in part, to the existence of four distinct receptors (EP1–4). This can complicate the analysis of the biological effects produced by PGE2. While there are currently selective pharmacological tools to explore the roles of the EP1,3,4 receptors in cellular and tissue responses, analysis of EP2 receptor-induced responses has bee...

  10. Microglial inhibition of neuroprotection by antagonists of the EP1 prostaglandin E2 receptor

    Directory of Open Access Journals (Sweden)

    Rojas Monica A

    2009-02-01

    Full Text Available Abstract Background The EP1 receptor for the prostanoid PGE2 is a G-protein coupled receptor that has been shown to contribute to excitotoxic neuronal death. In this study we examined the influence of non-neuronal cells on neuroprotective properties of EP1 receptor antagonists (Ono 8711 and SC 51089. Methods Primary neuronal cultures systems with or without non-neuronal cells were used to examine how the neuroprotective properties of EP1 antagonists were influenced by non-neuronal cells. The influence of astrocytes or microglia were individually tested in excitotoxicity assays using a co-culture system with these cells grown on permeable transwell inserts above the neuronal-enriched cultures. The influence of microglia on PGE2 synthesis and EP1 receptor expression was examined. Results EP1 antagonists were neuroprotective in neuronal-enriched cultures (> 90% neurons but not in mixed cultures (30% neurons plus other non-neuronal cells. Co-cultures of microglia on permeable transwell inserts above neuronal-enriched cultures blocked neuroprotection by EP1 antagonists. Incubation of microglia with neuronal-enriched cultures for 48 hours prior to NMDA challenge was sufficient to block neuroprotection by EP1 antagonists. The loss of neuroprotection by EP1 antagonists was accompanied by a decrease of neuronal EP1 expression in the nucleus in cultures with microglia present. Conclusion These findings demonstrate microglial modulation of neuronal excitotoxicity through interaction with the EP1 receptor and may have important implications in vivo where microglia are associated with neuronal injury.

  11. Modification of formalin-induced nociception by different histamine receptor agonists and antagonists.

    Science.gov (United States)

    Farzin, Davood; Nosrati, Farnaz

    2007-01-15

    The present study evaluated the effects of different histamine receptor agonists and antagonists on the nociceptive response in the mouse formalin test. Intracerebroventricular (20-40 microg/mouse i.c.v.) or subcutaneous (1-10 mg/kg s.c.) injection of HTMT (H(1) receptor agonist) elicited a dose-related hyperalgesia in the early and late phases. Conversely, intraperitoneal (20 and 30 mg/kg i.p.) injection of dexchlorpheniramine (H(1) receptor antagonist) was antinociceptive in both phases. At a dose ineffective per se, dexchlorpheniramine (10 mg/kg i.p.) antagonized the hyperalgesia induced by HTMT (40 mug/mouse i.c.v. or 10 mg/kg s.c.). Dimaprit (H(2) receptor agonist, 30 mg/kg i.p.) and ranitidine (H(2) receptor antagonist, 20 and 40 mg/kg i.p.) reduced the nociceptive responses in the early and late phases. No significant change in the antinociceptive activity was found following the combination of dimaprit (30 mg/kg i.p.) with ranitidine (10 mg/kg i.p.). The antinociceptive effect of dimaprit (30 mg/kg i.p.) was prevented by naloxone (5 mg/kg i.p.) in the early phase or by imetit (H(3) receptor agonist, 25 mg/kg i.p.) in both early and late phases. The histamine H(3) receptor agonist imetit was hyperalgesic following i.p. administration of 50 mg/kg. Imetit-induced hyperalgesia was completely prevented by treatment with a dose ineffective per se of thioperamide (H(3) receptor antagonist, 5 mg/kg i.p.). The results suggest that histamine H(1) and H(3) receptor activations increase sensitivity to nociceptive stimulus in the formalin test.

  12. Effects of GABAB receptor agonists and antagonists on glycemia regulation in mice.

    Science.gov (United States)

    Bonaventura, María M; Crivello, Martín; Ferreira, María Laura; Repetto, Martín; Cymeryng, Cora; Libertun, Carlos; Lux-Lantos, Victoria A

    2012-02-29

    γ-Aminobutyric acid (GABA) inhibits insulin secretion through GABA(B) receptors in pancreatic β-cells. We investigated whether GABA(B) receptors participated in the regulation of glucose homeostasis in vivo. BALB/c mice acutely pre-injected with the GABA(B) receptor agonist baclofen (7.5mg/kg, i.p.) presented glucose intolerance and diminished insulin secretion during a glucose tolerance test (GTT, 2g/kg body weight, i.p.). The GABA(B) receptor antagonist 2-hydroxysaclofen (15 mg/kg, i.p.) improved the GTT and reversed the baclofen effect. Also a slight increase in insulin secretion was observed with 2-hydroxysaclofen. In incubated islets 1.10(-5)M baclofen inhibited 20mM glucose-induced insulin secretion and this effect was reversed by coincubation with 1.10(-5)M 2-hydroxysaclofen. In chronically-treated animals (18 days) both the receptor agonist (5mg/kg/day i.p.) and the receptor antagonist (10mg/kg/day i.p.) induced impaired GTTs; the receptor antagonist, but not the agonist, also induced a decrease in insulin secretion. No alterations in insulin tolerance tests, body weight and food intake were observed with the treatments. In addition glucagon, insulin-like growth factor I, prolactin, corticosterone and growth hormone, other hormones involved in glucose metabolism regulation, were not affected by chronic baclofen or 2-hydroxysaclofen. In islets obtained from chronically injected animals with baclofen, 2-hydroxysaclofen or saline (as above), GABA(B2) mRNA expression was not altered. Results demonstrate that GABA(B) receptors are involved in the regulation of glucose homeostasis in vivo. Treatment with receptor agonists or antagonists, given acutely or chronically, altered glucose homeostasis and insulin secretion alerting to the need to evaluate glucose metabolism during the clinical use of these drugs. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. In vitro and in vivo pharmacological characterization of BIIL 284, a novel and potent leukotriene B(4) receptor antagonist.

    Science.gov (United States)

    Birke, F W; Meade, C J; Anderskewitz, R; Speck, G A; Jennewein, H M

    2001-04-01

    BIIL 284 is a new LTB(4) receptor antagonist. It is a prodrug and has negligible binding to the LTB(4) receptor. However, ubiquitous esterases metabolize BIIL 284 to the active metabolites BIIL 260 and BIIL 315, the glucuronidated form of BIIL 260. Both metabolites have high affinity to the LTB(4) receptor on isolated human neutrophil cell membranes with K(i) values of 1.7 and 1.9 nM, respectively. On vital human neutrophilic granulocytes K(i) was around 1 nM. BIIL 260 and BIIL 315 interact with the LTB(4) receptor in a saturable, reversible, and competitive manner. BIIL 260 and its glucuronide BIIL 315 also potently inhibited LTB(4)-induced intracellular Ca(2+) release in human neutrophils (IC(50) values of 0.82 and 0.75 nM, respectively) as measured with Fura-2. High efficacy of BIIL 284 has been demonstrated in various in vivo models. BIIL 284 inhibited LTB(4)-induced mouse ear inflammation with ED(50) = 0.008 mg/kg p.o., LTB(4)-induced transdermal chemotaxis in guinea pigs with ED(50) = 0.03 mg/kg p.o., LTB(4)-induced neutropenia in various species (monkey: ED(50) = 0.004 mg/kg p.o.), and LTB(4)-induced Mac1-expression in monkeys (ED(50) = 0.05 mg/kg p.o. in Tylose). Full blockade of LTB(4) receptors over 24 h was achieved by 0.3 mg/kg BIIL 284 after single oral dose as measured by LTB(4)-induced neutropenia or Mac1-expression in the monkey model. BIIL 284 is an unusually potent and long-acting orally active LTB(4) antagonist, and is therefore under clinical development as a novel anti-inflammatory principle.

  14. Positive Modulatory Interactions of NMDA Receptor GluN1/2B Ligand Binding Domains Attenuate Antagonists Activity

    Directory of Open Access Journals (Sweden)

    Douglas Bledsoe

    2017-05-01

    Full Text Available N-methyl D-aspartate receptors (NMDAR play crucial role in normal brain function and pathogenesis of neurodegenerative and psychiatric disorders. Functional tetra-heteromeric NMDAR contains two obligatory GluN1 subunits and two identical or different non-GluN1 subunits that include six different gene products; four GluN2 (A–D and two GluN3 (A–B subunits. The heterogeneity of subunit combination facilities the distinct function of NMDARs. All GluN subunits contain an extracellular N-terminal Domain (NTD and ligand binding domain (LBD, transmembrane domain (TMD and an intracellular C-terminal domain (CTD. Interaction between the GluN1 and co-assembling GluN2/3 subunits through the LBD has been proven crucial for defining receptor deactivation mechanisms that are unique for each combination of NMDAR. Modulating the LBD interactions has great therapeutic potential. In the present work, by amino acid point mutations and electrophysiology techniques, we have studied the role of LBD interactions in determining the effect of well-characterized pharmacological agents including agonists, competitive antagonists, and allosteric modulators. The results reveal that agonists (glycine and glutamate potency was altered based on mutant amino acid sidechain chemistry and/or mutation site. Most antagonists inhibited mutant receptors with higher potency; interestingly, clinically used NMDAR channel blocker memantine was about three-fold more potent on mutated receptors (N521A, N521D, and K531A than wild type receptors. These results provide novel insights on the clinical pharmacology of memantine, which is used for the treatment of mild to moderate Alzheimer's disease. In addition, these findings demonstrate the central role of LBD interactions that can be exploited to develop novel NMDAR based therapeutics.

  15. Rational Design of Potent Antagonists to the Human Growth Hormone Receptor

    Science.gov (United States)

    Fuh, Germaine; Cunningham, Brian C.; Fukunaga, Rikiro; Nagata, Shigekazu; Goeddel, David V.; Wells, James A.

    1992-06-01

    A hybrid receptor was constructed that contained the extracellular binding domain of the human growth hormone (hGH) receptor linked to the transmembrane and intracellular domains of the murine granulocyte colony-stimulating factor receptor. Addition of hGH to a myeloid leukemia cell line (FDC-P1) that expressed the hybrid receptor caused proliferation of these cells. The mechanism for signal transduction of the hybrid receptor required dimerization because monoclonal antibodies to the hGH receptor were agonists whereas their monovalent fragments were not. Receptor dimerization occurs sequentially-a receptor binds to site 1 on hGH, and then a second receptor molecule binds to site 2 on hGH. On the basis of this sequential mechanism, which may occur in many other cytokine receptors, inactive hGH analogs were designed that were potent antagonists to hGH-induced cell proliferation. Such antagonists could be useful for treating clinical conditions of hGH excess, such as acromegaly.

  16. (-) Arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β.

    Science.gov (United States)

    Ogungbe, Ifedayo Victor; Crouch, Rebecca A; Demeritte, Teresa

    2014-11-24

    Lignans are important biologically active dietary polyphenolic compounds. Consumption of foods that are rich in lignans is associated with positive health effects. Using modeling tools to probe the ligand-binding pockets of molecular receptors, we found that lignans have high docking affinity for the human thyroid hormone receptor β. Follow-up experimental results show that lignans (-) arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β. The modeled complexes show key plausible interactions between the two ligands and important amino acid residues of the receptor.

  17. (−) Arctigenin and (+) Pinoresinol Are Antagonists of the Human Thyroid Hormone Receptor β

    Science.gov (United States)

    2015-01-01

    Lignans are important biologically active dietary polyphenolic compounds. Consumption of foods that are rich in lignans is associated with positive health effects. Using modeling tools to probe the ligand-binding pockets of molecular receptors, we found that lignans have high docking affinity for the human thyroid hormone receptor β. Follow-up experimental results show that lignans (−) arctigenin and (+) pinoresinol are antagonists of the human thyroid hormone receptor β. The modeled complexes show key plausible interactions between the two ligands and important amino acid residues of the receptor. PMID:25383984

  18. Discovery of Potent and Highly Selective A2B Adenosine Receptor Antagonist Chemotypes.

    Science.gov (United States)

    El Maatougui, Abdelaziz; Azuaje, Jhonny; González-Gómez, Manuel; Miguez, Gabriel; Crespo, Abel; Carbajales, Carlos; Escalante, Luz; García-Mera, Xerardo; Gutiérrez-de-Terán, Hugo; Sotelo, Eddy

    2016-03-10

    Three novel families of A2B adenosine receptor antagonists were identified in the context of the structural exploration of the 3,4-dihydropyrimidin-2(1H)-one chemotype. The most appealing series contain imidazole, 1,2,4-triazole, or benzimidazole rings fused to the 2,3-positions of the parent diazinone core. The optimization process enabled identification of a highly potent (3.49 nM) A2B ligand that exhibits complete selectivity toward A1, A2A, and A3 receptors. The results of functional cAMP experiments confirmed the antagonistic behavior of representative ligands. The main SAR trends identified within the series were substantiated by a molecular modeling study based on a receptor-driven docking model constructed on the basis of the crystal structure of the human A2A receptor.

  19. Exploiting Receptor Competition to Enhance Nanoparticle Binding Selectivity

    Science.gov (United States)

    Angioletti-Uberti, Stefano

    2017-02-01

    Nanoparticles functionalized with multiple ligands can be programed to bind biological targets depending on the receptors they express, providing a general mechanism exploited in various technologies, from selective drug delivery to biosensing. For binding to be highly selective, ligands should exclusively interact with specific targeted receptors, because the formation of bonds with other, untargeted ones would lead to nonspecific binding and potentially harmful behavior. This poses a particular problem for multivalent nanoparticles, because even very weak bonds can collectively lead to strong binding. A statistical mechanical model is used here to describe how competition between different receptors together with multivalent effects can be harnessed to design ligand-functionalized nanoparticles insensitive to the presence of untargeted receptors, preventing nonspecific binding.

  20. Competitive antagonism of AMPA receptors by ligands of different classes

    DEFF Research Database (Denmark)

    Hogner, Anders; Greenwood, Jeremy R; Liljefors, Tommy

    2003-01-01

    that ATPO and DNQX stabilize an open form of the ligand-binding core by different sets of interactions. Computational techniques are used to quantify the differences between these two ligands and to map the binding site. The isoxazole moiety of ATPO acts primarily as a spacer, and other scaffolds could......-(phosphonomethoxy)-4-isoxazolyl]propionic acid (ATPO) in complex with the ligand-binding core of the receptor. Comparison with the only previous structure of the ligand-binding core in complex with an antagonist, 6,7-dinitro-2,3-quinoxalinedione (DNQX) (Armstrong, N.; Gouaux, E. Neuron 2000, 28, 165-181), reveals...

  1. AMPA and GABA receptor antagonists and their interaction in rats with a genetic form of absence epilepsy

    NARCIS (Netherlands)

    Kaminski, R.M.; Rijn, C.M. van; Turski, W.A.; Czuczwar, S.J.; Luijtelaar, E.L.J.M. van

    2001-01-01

    The effects of combined and single administration of the -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, 7,8-methylenedioxy-1-(4-aminophenyl)-4-methyl-3-acetyl-4,5-dihydro-2,3 -benzodiazepine (LY 300164), and of the GABAB receptor antagonist -aminopropyl-n-butyl-phosp

  2. Histamine H3 receptor antagonist decreases cue-induced alcohol reinstatement in mice.

    Science.gov (United States)

    Nuutinen, Saara; Mäki, Tiia; Rozov, Stanislav; Bäckström, Pia; Hyytiä, Petri; Piepponen, Petteri; Panula, Pertti

    2016-07-01

    We have earlier found that the histamine H3 receptor (H3R) antagonism diminishes motivational aspects of alcohol reinforcement in mice. Here we studied the role of H3Rs in cue-induced reinstatement of alcohol seeking in C57BL/6J mice using two different H3R antagonists. Systemic administration of H3R antagonists attenuated cue-induced alcohol seeking suggesting that H3R antagonists may reduce alcohol craving. To understand how alcohol affects dopamine and histamine release, a microdialysis study was performed on C57BL/6J mice and the levels of histamine, dopamine and dopamine metabolites were measured in the nucleus accumbens. Alcohol administration was combined with an H3R antagonist pretreatment to reveal whether modulation of H3R affects the effects of alcohol on neurotransmitter release. Alcohol significantly increased the release of dopamine in the nucleus accumbens but did not affect histamine release. Pretreatment with H3R antagonist ciproxifan did not modify the effect of alcohol on dopamine release. However, histamine release was markedly increased with ciproxifan. In conclusion, our findings demonstrate that H3R antagonism attenuates cue-induced reinstatement of alcohol seeking in mice. Alcohol alone does not affect histamine release in the nucleus accumbens but H3R antagonist instead increases histamine release significantly suggesting that the mechanism by which H3R antagonist inhibits alcohol seeking found in the present study and the decreased alcohol reinforcement, reward and consumption found earlier might include alterations in the histaminergic neurotransmission in the nucleus accumbens. These findings imply that selective antagonists of H3Rs could be a therapeutic strategy to prevent relapse and possibly diminish craving to alcohol use. This article is part of the Special Issue entitled 'Histamine Receptors'.

  3. Synthesis and dual histamine H₁ and H₂ receptor antagonist activity of cyanoguanidine derivatives.

    Science.gov (United States)

    Sadek, Bassem; Alisch, Rudi; Buschauer, Armin; Elz, Sigurd

    2013-11-15

    Premedication with a combination of histamine H₁ receptor (H₁R) and H₂ receptor (H₂R) antagonists has been suggested as a prophylactic principle, for instance, in anaesthesia and surgery. Aiming at pharmacological hybrids combining H₁R and H₂R antagonistic activity, a series of cyanoguanidines 14-35 was synthesized by linking mepyramine-type H₁R antagonist substructures with roxatidine-, tiotidine-, or ranitidine-type H₂R antagonist moieties. N-desmethylmepyramine was connected via a poly-methylene spacer to a cyanoguanidine group as the "urea equivalent" of the H₂R antagonist moiety. The title compounds were screened for histamine antagonistic activity at the isolated ileum (H₁R) and the isolated spontaneously beating right atrium (H₂R) of the guinea pig. The results indicate that, depending on the nature of the H₂R antagonist partial structure, the highest H₁R antagonist potency resided in roxatidine-type compounds with spacers of six methylene groups in length (compound 21), and tiotidine-type compounds irrespective of the alkyl chain length (compounds 28, 32, 33), N-cyano-N'-[2-[[(2-guanidino-4-thiazolyl)methyl]thio]ethyl]-N″-[2-[N-[2-[N-(4-methoxybenzyl)-N-(pyridyl)-amino] ethyl]-N-methylamino]ethyl] guanidine (25, pKB values: 8.05 (H₁R, ileum) and 7.73 (H₂R, atrium) and the homologue with the mepyramine moiety connected by a six-membered chain to the tiotidine-like partial structure (compound 32, pKB values: 8.61 (H₁R) and 6.61 (H₂R) were among the most potent hybrid compounds. With respect to the development of a potential pharmacotherapeutic agent, structural optimization seems possible through selection of other H₁R and H₂R pharmacophoric moieties with mutually affinity-enhancing properties.

  4. Synthesis and Dual Histamine H1 and H2 Receptor Antagonist Activity of Cyanoguanidine Derivatives

    Directory of Open Access Journals (Sweden)

    Bassem Sadek

    2013-11-01

    Full Text Available Premedication with a combination of histamine H1 receptor (H1R and H2 receptor (H2R antagonists has been suggested as a prophylactic principle, for instance, in anaesthesia and surgery. Aiming at pharmacological hybrids combining H1R and H2R antagonistic activity, a series of cyanoguanidines 14–35 was synthesized by linking mepyramine-type H1R antagonist substructures with roxatidine-, tiotidine-, or ranitidine-type H2R antagonist moieties. N-desmethylmepyramine was connected via a poly-methylene spacer to a cyanoguanidine group as the “urea equivalent” of the H2R antagonist moiety. The title compounds were screened for histamine antagonistic activity at the isolated ileum (H1R and the isolated spontaneously beating right atrium (H2R of the guinea pig. The results indicate that, depending on the nature of the H2R antagonist partial structure, the highest H1R antagonist potency resided in roxatidine-type compounds with spacers of six methylene groups in length (compound 21, and tiotidine-type compounds irrespective of the alkyl chain length (compounds 28, 32, 33, N-cyano-N'-[2-[[(2-guanidino-4-thiazolylmethyl]thio]ethyl]-N″-[2-[N-[2-[N-(4-methoxybenzyl-N-(pyridyl-amino] ethyl]-N-methylamino]ethyl] guanidine (25, pKB values: 8.05 (H1R, ileum and 7.73 (H2R, atrium and the homologue with the mepyramine moiety connected by a six-membered chain to the tiotidine-like partial structure (compound 32, pKB values: 8.61 (H1R and 6.61 (H2R were among the most potent hybrid compounds. With respect to the development of a potential pharmacotherapeutic agent, structural optimization seems possible through selection of other H1R and H2R pharmacophoric moieties with mutually affinity-enhancing properties.

  5. Tetrazolyl isoxazole amino acids as ionotropic glutamate receptor antagonists: synthesis, modelling and molecular pharmacology.

    Science.gov (United States)

    Frølund, Bente; Greenwood, Jeremy R; Holm, Mai M; Egebjerg, Jan; Madsen, Ulf; Nielsen, Birgitte; Bräuner-Osborne, Hans; Stensbøl, Tine B; Krogsgaard-Larsen, Povl

    2005-09-15

    Two 3-(5-tetrazolylmethoxy) analogues, 1a and 1b, of (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA), a selective AMPA receptor agonist, and (RS)-2-amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid (ATPA), a GluR5-preferring agonist, were synthesized. Compounds 1a and 1b were pharmacologically characterized in receptor binding assays, and electrophysiologically on homomeric AMPA receptors (GluR1-4), homomeric (GluR5 and GluR6) and heteromeric (GluR6/KA2) kainic acid receptors, using two-electrode voltage-clamped Xenopus laevis oocytes expressing these receptors. Both analogues proved to be antagonists at all AMPA receptor subtypes, showing potencies (Kb=38-161 microM) similar to that of the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4-isoxazolyl]propionic acid (AMOA) (Kb=43-76 microM). Furthermore, the AMOA analogue, 1a, blocked two kainic acid receptor subtypes (GluR5 and GluR6/KA2), showing sevenfold preference for GluR6/KA2 (Kb=19 microM). Unlike the iGluR antagonist (S)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl]propionic acid [(S)-ATPO], the corresponding tetrazolyl analogue, 1b, lacks kainic acid receptor effects. On the basis of docking to a crystal structure of the isolated extracellular ligand-binding core of the AMPA receptor subunit GluR2 and a homology model of the kainic acid receptor subunit GluR5, we were able to rationalize the observed structure-activity relationships.

  6. Orexin Receptor Antagonists: New Therapeutic Agents for the Treatment of Insomnia.

    Science.gov (United States)

    Roecker, Anthony J; Cox, Christopher D; Coleman, Paul J

    2016-01-28

    Since its discovery in 1998, the orexin system, composed of two G-protein coupled receptors, orexins 1 and 2, and two neuropeptide agonists, orexins A and B, has captured the attention of the scientific community as a potential therapeutic target for the treatment of obesity, anxiety, and sleep/wake disorders. Genetic evidence in rodents, dogs, and humans was revealed between 1999 and 2000, demonstrating a causal link between dysfunction or deletion of the orexin system and narcolepsy, a disorder characterized by hypersomnolence during normal wakefulness. These findings encouraged efforts to discover agonists to treat narcolepsy and, alternatively, antagonists to treat insomnia. This perspective will focus on the discovery and development of structurally diverse orexin antagonists suitable for preclinical pharmacology studies and human clinical trials. The work described herein culminated in the 2014 FDA approval of suvorexant as a first-in-class dual orexin receptor antagonist for the treatment of insomnia.

  7. Effect of mineralocorticoid receptor antagonists on proteinuria and progression of chronic kidney disease

    DEFF Research Database (Denmark)

    Currie, Gemma; Taylor, Alison H M; Fujita, Toshiro

    2016-01-01

    BACKGROUND: Hypertension and proteinuria are critically involved in the progression of chronic kidney disease. Despite treatment with renin angiotensin system inhibition, kidney function declines in many patients. Aldosterone excess is a risk factor for progression of kidney disease. Hyperkalaemia...... is a concern with the use of mineralocorticoid receptor antagonists. We aimed to determine whether the renal protective benefits of mineralocorticoid antagonists outweigh the risk of hyperkalaemia associated with this treatment in patients with chronic kidney disease. METHODS: We conducted a meta......-analysis investigating renoprotective effects and risk of hyperkalaemia in trials of mineralocorticoid receptor antagonists in chronic kidney disease. Trials were identified from MEDLINE (1966-2014), EMBASE (1947-2014) and the Cochrane Clinical Trials Database. Unpublished summary data were obtained from investigators...

  8. Pathophysiology of the cysteinyl leukotrienes and effects of leukotriene receptor antagonists in asthma

    DEFF Research Database (Denmark)

    Bisgaard, H

    2001-01-01

    Cysteinyl leukotrienes, synthesized de novo from cell membrane phospholipids, are proinflammatory mediators that play an important role in the pathophysiology of asthma. These mediators are among the most potent of bronchoconstrictors and cause vasodilation, increased microvascular permeability, ...... antagonists are additive with those of beta agonists. These data provide strong support for the use of leukotriene receptor antagonists for treating asthma.......Cysteinyl leukotrienes, synthesized de novo from cell membrane phospholipids, are proinflammatory mediators that play an important role in the pathophysiology of asthma. These mediators are among the most potent of bronchoconstrictors and cause vasodilation, increased microvascular permeability...... ciliary motility, which may hinder mucociliary clearance. Asthmatic patients demonstrate increased production of cysteinyl leukotrienes during naturally occurring asthma and acute asthma attacks as well as after allergen and exercise challenge. The leukotriene receptor antagonists montelukast, zafirlukast...

  9. Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions

    Energy Technology Data Exchange (ETDEWEB)

    Steranka, L.R.; Manning, D.C.; DeHaas, C.J.; Ferkany, J.W.; Borosky, S.A.; Connor, J.R.; Vavrek, R.J.; Stewart, J.M.; Snyder, S.H.

    1988-05-01

    Autoradiographic studies localize (/sup 3/H)bradykinin receptor binding sites to the substantia gelatinosa, dorsal root, and a subset of small cells in both the dorsal root and trigeminal ganglia of the guinea pig. (/sup 3/H)Bradykinin labeling is also observed over myocardinal/coronary visceral afferent fibers. The localization of (/sup 3/H)bradykinin receptors to nociceptive pathways supports a role for bradykinin in pain mediation. Several bradkykinin antagonists block bradykinin-induced acute vascular pain in the rat. The bradykinin antagonists also relieve bradykinin- and urate-induced hyperalgesia in the rat paw. These results indicate that bradykinin is a physiologic mediator of pain and that bradykinin antagonists have analgesic activity in both acute and chronic pain models.

  10. Remote functionalization of SCH 39166: discovery of potent and selective benzazepine dopamine D1 receptor antagonists.

    Science.gov (United States)

    Sasikumar, T K; Burnett, Duane A; Greenlee, William J; Smith, Michelle; Fawzi, Ahmad; Zhang, Hongtao; Lachowicz, Jean E

    2010-02-01

    A series of novel benzazepine derived dopamine D(1) antagonists have been discovered. These compounds are highly potent at D(1) and showed excellent selectivity over D(2) and D(4) receptors. SAR studies revealed that a variety of functional groups are tolerated on the D-ring of known tetracyclic benzazepine analog 2, SCH 39166, leading to compounds with nanomolar potency at D(1) and good selectivity over D(2)-like receptors.

  11. Ionotropic excitatory amino acid receptor ligands. Synthesis and pharmacology of a new amino acid AMPA antagonist

    DEFF Research Database (Denmark)

    Madsen, U; Sløk, F A; Stensbøl, T B;

    2000-01-01

    We have previously described the potent and selective (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA), and the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4......-isoxazolyl]propionic acid (AMOA). Using these AMPA receptor ligands as leads, a series of compounds have been developed as tools for further elucidation of the structural requirements for activation and blockade of AMPA receptors. The synthesized compounds have been tested for activity at ionotropic...... excitatory amino acid (EAA) receptors using receptor binding and electrophysiological techniques, and for activity at metabotropic EAA receptors using second messenger assays. Compounds 1 and 4 were essentially inactive. (RS)-2-Amino-3-[3-(2-carboxyethyl)-5-methyl-4-isoxazolyl]propionic acid (ACMP, 2...

  12. Bartonella quintana lipopolysaccharide is a natural antagonist of Toll-like receptor 4.

    NARCIS (Netherlands)

    Popa, C.; Abdollahi-Roodsaz, S.; Joosten, L.A.B.; Takahashi, N.; Sprong, T.; Matera, G.; Liberto, M.C.; Foca, A.; Deuren, M. van; Kullberg, B.J.; Berg, W.B. van den; Meer, J.W.M. van der; Netea, M.G.

    2007-01-01

    Bartonella quintana is a gram-negative microorganism that causes trench fever and chronic bacteremia. B. quintana lipopolysaccharide (LPS) was unable to induce the production of proinflammatory cytokines in human monocytes. Interestingly, B. quintana LPS is a potent antagonist of Toll-like receptor

  13. Luteinizing hormone-releasing hormone receptor antagonist may reduce postmenopausal flushing

    NARCIS (Netherlands)

    Gastel, P. van; Zanden, M. van der; Telting, D.; Filius, M.; Bancsi, L.; Boer, H. de

    2012-01-01

    OBJECTIVE: Hormone therapy (HT) is the most effective treatment of postmenopausal (PMP) flushing; however, its use is often contraindicated. As an alternative option, we explored the efficacy of the luteinizing hormone-releasing hormone (LHRH) receptor antagonist cetrorelix in women with severe PMP

  14. Bicyclams, selective antagonists of the human chemokine receptor CXCR4, potently inhibit feline immunodeficiency virus replication

    NARCIS (Netherlands)

    Horzinek, M.C.; Egberink, H.F.; Clercq, E. de; Vliet, A.L.W. van; Balzarini, J.; Bridger, G.J.; Henson, G.; Schols, D.

    1999-01-01

    Bicyclams are low-molecular-weight anti-human immunodeficiency virus (HIV) agents that have been shown to act as potent and selective CXC chemokine receptor 4 (CXCR4) antagonists. Here, we demonstrate that bicyclams are potent inhibitors of feline immunodeficiency virus (FIV) replication when evalua

  15. Novel Small Molecule Antagonists of the Interaction of the Androgen Receptor and Transcriptional Co-regulators

    Science.gov (United States)

    2009-01-01

    Netherlands ) (see appendices). Small Molecule Inhibitors of the Androgen Receptor Transcriptional Activity for Prostate Cancer Drug Discovery...peritoneal injection, tail injection, oral gavage, retro-orbital blood sampling, isoflurane anesthesia, CO2 euthanasia , cardiac stick, organ harvesting...Discovery Poster Award, Androgens 2008 Meeting, Rotterdam (The Netherlands ), October 2008 Novel Small Molecules Antagonists of the Interaction of

  16. Predictors of Congestive Heart Failure after Treatment with an Endothelin Receptor Antagonist

    NARCIS (Netherlands)

    Hoekman, Jamo; Lambers Heerspink, Hiddo; Viberti, Giancarlo; Green, Damien; Mann, Johannes F. E.; de Zeeuw, Dick

    2014-01-01

    Background and objectives The Avosentan on Time to Doubling of Serum Creatinine, End Stage Renal Disease or Death (ASCEND) trial tested the renoprotective effect of the endothelin receptor antagonist avosentan in patients with diabetes and nephropathy, but the study was terminated due to an excess o

  17. Effect of the cannabinoid receptor-1 antagonist rimonabant on lipolysis in rats

    DEFF Research Database (Denmark)

    Mølhøj, Signe; Hansen, Harald S; Schweiger, Martina

    2010-01-01

    The cannabinoid receptor 1 antagonist, rimonabant, reduces food intake and body weight, but contradictory findings have been reported as to whether the weight-reducing effect is fully accounted for by the reduced food intake or if rimonabant also mediates a lipolytic effect. In the present study...

  18. I. Effects of a Dopamine Receptor Antagonist on Fathead Minnow, Pimephales promelas ,Reproduction

    Science.gov (United States)

    This study used a 21 d fathead minnow (Pimephales promelas) reproduction assay to test the hypothesis that exposure to the dopamine 2 receptor (D2R) antagonist, haloperidol, would impair fish reproduction. Additionally, a 96 h experiment with fathead minnows and zebrafish (Danio ...

  19. Mineralocorticoid receptor antagonists for heart failure with reduced ejection fraction : integrating evidence into clinical practice

    NARCIS (Netherlands)

    Zannad, Faiez; Stough, Wendy Gattis; Rossignol, Patrick; Bauersachs, Johann; McMurray, John J. V.; Swedberg, Karl; Struthers, Allan D.; Voors, Adriaan A.; Ruilope, Luis M.; Bakris, George L.; O'Connor, Christopher M.; Gheorghiade, Mihai; Mentz, Robert J.; Cohen-Solal, Alain; Maggioni, Aldo P.; Beygui, Farzin; Filippatos, Gerasimos S.; Massy, Ziad A.; Pathak, Atul; Pina, Ileana L.; Sabbah, Hani N.; Sica, Domenic A.; Tavazzi, Luigi; Pitt, Bertram

    2012-01-01

    Mineralocorticoid receptor antagonists (MRAs) improve survival and reduce morbidity in patients with heart failure, reduced ejection fraction (HFREF), and mild-to-severe symptoms, and in patients with left ventricular systolic dysfunction and heart failure after acute myocardial infarction. These cl

  20. Analysis of Agonist and Antagonist Effects on Thyroid Hormone Receptor Conformation by Hydrogen/Deuterium Exchange

    NARCIS (Netherlands)

    Figueira, A C M; Saidemberg, D M; Telles de Souza, Paulo; Martínez, L; Scanlan, T S; Baxter, J D; Skaf, M S; Palma, M S; Webb, P M; Polikarpov, I

    2011-01-01

    Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains i

  1. Long-term use of aldosterone-receptor antagonists in uncontrolled hypertension: A retrospective analysis

    NARCIS (Netherlands)

    P.M. Jansen (Pieter); K. Verdonk (Koen); B.P. Imholz (Ben); A.H.J. Danser (Jan); A.H. van den Meiracker (Anton)

    2011-01-01

    textabstractBackground. The long-term efficacy of aldosterone-receptor antagonists (ARAs) as add-on treatment in uncontrolled hypertension has not yet been reported. Methods. Data from 123 patients (21 with primary aldosteronism, 102 with essential hypertension) with difficult-to-treat hypertension

  2. Pyrazolo Derivatives as Potent Adenosine Receptor Antagonists: An Overview on the Structure-Activity Relationships

    Directory of Open Access Journals (Sweden)

    Siew Lee Cheong

    2011-01-01

    Full Text Available In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A1, A2A, A2B, and A3 has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.

  3. N-Oxide analogs of WAY-100635 : new high affinity 5-HT (1A) receptor antagonists

    NARCIS (Netherlands)

    Oberwinkler - Marchais, Sandrine; Nowicki, B; Pike, VW; Halldin, C; Sandell, J; Chou, YH; Gulyas, B; Brennum, LT; Farde, L; Wikstrom, H V

    2005-01-01

    WAY-100635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl)ethyl))-N-(2-pyridinyl)cyclohexanecarboxamide] 1 and its O-des-methyl derivative DWAY 2 are well-known high affinity 5-HT1A receptor antagonists. which when labeled with carbon-II (beta(+): t(1/2) 20.4min) in the carbonyl group are effective radiol

  4. N-Oxide analogs of WAY-100635 : new high affinity 5-HT1A receptor antagonists

    NARCIS (Netherlands)

    Marchais-Oberwinkler, S; Nowicki, B; Pike, VW; Halldin, C; Sandell, J; Chou, YH; Gulyas, B; Brennum, LT; Farde, L; Wikstrom, HV

    2005-01-01

    WAY-100635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl)ethyl))-N-(2-pyridinyl)cyclohexanecarboxamide] 1 and its O-des-methyl derivative DWAY 2 are well-known high affinity 5-HT1A receptor antagonists. which when labeled with carbon-II (beta(+): t(1/2) 20.4min) in the carbonyl group are effective radiol

  5. Sustained effects of interleukin-1 receptor antagonist treatment in type 2 diabetes

    DEFF Research Database (Denmark)

    Larsen, Claus M; Faulenbach, Mirjam; Vaag, Allan

    2009-01-01

    OBJECTIVE: Interleukin (IL)-1 impairs insulin secretion and induces beta-cell apoptosis. Pancreatic beta-cell IL-1 expression is increased and interleukin-1 receptor antagonist (IL-1Ra) expression reduced in patients with type 2 diabetes. Treatment with recombinant IL-1Ra improves glycemia and beta...

  6. Evidence for homogeneity of thromboxane A2 receptor using structurally different antagonists.

    Science.gov (United States)

    Swayne, G T; Maguire, J; Dolan, J; Raval, P; Dane, G; Greener, M; Owen, D A

    1988-08-01

    Nine structurally dissimilar thromboxane antagonists (SQ 29548, ICI 185282, AH 23848, BM 13505 (Daltroban), BM 13177 (Sulotroban), SK&F 88046, L-636499, L-640035 and a Bayer compound SK&F 47821) were studied for activity as thromboxane A2 receptor antagonists. The assays used were inhibition of responses induced by the thromboxane mimetic, U46619, on human washed platelet aggregation, rabbit platelet aggregation, rabbit aortic strip contraction, anaesthetised guinea-pig bronchoconstriction, and a radio-labelled ligand (125I-PTA-OH) binding assay as a measure of affinity for the human platelet receptor. The results of the present study, with activities spanning at least four orders of magnitude along with statistically significant correlations (at least P less than 0.01), strongly suggests that between assays, antagonists and species a homogenous population of thromboxane A2 receptors exists. This finding is in contrast to those of a close series of 13-azapinane antagonists studied by other workers which have suggested receptor heterogeneity.

  7. Effect of the Urotensin Receptor Antagonist Palosuran in Hypertensive Patients With Type 2 Diabetic Nephropathy

    NARCIS (Netherlands)

    L. Vogt; C. Chiurchiu; H. Chadha-Boreham; P. Danaietash; J. Dingemanse; S. Hadjadj; H. Krum; G. Navis; E. Neuhart; A.I. Parvanova; P. Ruggenenti; A.J. Woittiez; R. Zimlichman; G. Remuzzi; D. de Zeeuw

    2010-01-01

    The urotensin system has been hypothesized to play an important role in the pathophysiology of diabetic nephropathy. In this multicenter, randomized, double-blind, placebo-controlled, 2-period crossover study, the effects of the urotensin receptor antagonist palosuran on urinary albumin excretion an

  8. Effect of the calcitonin gene-related peptide (CGRP) receptor antagonist telcagepant in human cranial arteries

    NARCIS (Netherlands)

    L. Edvinsson (Lars); K.Y. Chan (Kayi); S. Eftekhari; E. Nilsson (Elisabeth); R. de Vries (René); H. Säveland (Hans); C.M.F. Dirven (Clemens); A.H.J. Danser (Jan)

    2010-01-01

    textabstractIntroduction: Calcitonin gene-related peptide (CGRP) is a neuronal messenger in intracranial sensory nerves and is considered to play a significant role in migraine pathophysiology. Materials and methods: We investigated the effect of the CGRP receptor antagonist, telcagepant, on CGRP-in

  9. Design, synthesis, and biological evaluation of 4-phenylpyrrole derivatives as novel androgen receptor antagonists.

    Science.gov (United States)

    Yamamoto, Satoshi; Matsunaga, Nobuyuki; Hitaka, Takenori; Yamada, Masami; Hara, Takahito; Miyazaki, Junichi; Santou, Takashi; Kusaka, Masami; Yamaoka, Masuo; Kanzaki, Naoyuki; Furuya, Shuichi; Tasaka, Akihiro; Hamamura, Kazumasa; Ito, Mitsuhiro

    2012-01-01

    A series of 4-phenylpyrrole derivatives D were designed, synthesized, and evaluated for their potential as novel orally available androgen receptor antagonists therapeutically effective against castration-resistant prostate cancers. 4-Phenylpyrrole compound 1 exhibited androgen receptor (AR) antagonistic activity against T877A and W741C mutant-type ARs as well as wild-type AR. An arylmethyl group incorporated into compound 1 contributed to enhancement of antagonistic activity. Compound 4n, 1-{[6-chloro-5-(hydroxymethyl)pyridin-3-yl]methyl}-4-(4-cyanophenyl)-2,5-dimethyl-1H-pyrrole-3-carbonitrile exhibited inhibitory effects on tumor cell growth against the bicalutamide-resistant LNCaP-cxD2 cell line as well as the androgen receptor-dependent JDCaP cell line in a mouse xenograft model. These results demonstrate that this series of pyrrole compounds are novel androgen receptor antagonists with efficacy against prostate cancer cells, including castration-resistant prostate cancers such as bicalutamide-resistant prostate cancer.

  10. Analysis of Agonist and Antagonist Effects on Thyroid Hormone Receptor Conformation by Hydrogen/Deuterium Exchange

    NARCIS (Netherlands)

    Figueira, A C M; Saidemberg, D M; Telles de Souza, Paulo; Martínez, L; Scanlan, T S; Baxter, J D; Skaf, M S; Palma, M S; Webb, P M; Polikarpov, I

    Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains

  11. Cannabinoid receptor antagonists and the metabolic syndrome: Novel promising therapeutical approaches.

    Science.gov (United States)

    Cervino, C; Pasquali, R; Pagotto, U

    2007-01-01

    Recent findings in animals and in humans have shown that cannabinoid type 1 receptor antagonists are suitable to become the most promising validated class of drugs to tackle obesity and related disorders. This mini-review will provide a concise and updated revision of the state of art on this topic.

  12. A cross-laboratory preclinical study on the effectiveness of interleukin-1 receptor antagonist in stroke.

    Science.gov (United States)

    Maysami, Samaneh; Wong, Raymond; Pradillo, Jesus M; Denes, Adam; Dhungana, Hiramani; Malm, Tarja; Koistinaho, Jari; Orset, Cyrille; Rahman, Mahbubur; Rubio, Marina; Schwaninger, Markus; Vivien, Denis; Bath, Philip M; Rothwell, Nancy J; Allan, Stuart M

    2016-03-01

    Stroke represents a global challenge and is a leading cause of permanent disability worldwide. Despite much effort, translation of research findings to clinical benefit has not yet been successful. Failure of neuroprotection trials is considered, in part, due to the low quality of preclinical studies, low level of reproducibility across different laboratories and that stroke co-morbidities have not been fully considered in experimental models. More rigorous testing of new drug candidates in different experimental models of stroke and initiation of preclinical cross-laboratory studies have been suggested as ways to improve translation. However, to our knowledge, no drugs currently in clinical stroke trials have been investigated in preclinical cross-laboratory studies. The cytokine interleukin 1 is a key mediator of neuronal injury, and the naturally occurring interleukin 1 receptor antagonist has been reported as beneficial in experimental studies of stroke. In the present paper, we report on a preclinical cross-laboratory stroke trial designed to investigate the efficacy of interleukin 1 receptor antagonist in different research laboratories across Europe. Our results strongly support the therapeutic potential of interleukin 1 receptor antagonist in experimental stroke and provide further evidence that interleukin 1 receptor antagonist should be evaluated in more extensive clinical stroke trials.

  13. Pharmacological characterization of LY233053: A structurally novel tetrazole-substituted competitive N-methyl-D-aspartic acid antagonist with a short duration of action

    Energy Technology Data Exchange (ETDEWEB)

    Schoepp, D.D.; Ornstein, P.L.; Leander, J.D.; Lodge, D.; Salhoff, C.R.; Zeman, S.; Zimmerman, D.M. (Eli Lilly and Company, Indianapolis, IN (USA))

    1990-12-01

    This study reports the activity of a structurally novel excitatory amino acid receptor antagonist, LY233053 (cis-(+-)-4-((2H-tetrazol-5-yl)methyl)piperidine-2-carboxylic acid), the first tetrazole-containing competitive N-methyl-D-aspartic acid (NMDA) antagonist. LY233053 potently inhibited NMDA receptor binding to rat brain membranes as shown by the in vitro displacement of (3H) CGS19755 (IC50 = 107 +/- 7 nM). No appreciable affinity in (3H)alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) or (3H)kainate binding assays was observed (IC50 values greater than 10,000 nM). In vitro NMDA receptor antagonist activity was further demonstrated by selective inhibition of NMDA-induced depolarization in cortical wedges (IC50 = 4.2 +/- 0.4 microM vs. 40 microM NMDA). LY233053 was effective after in vivo systemic administration in a number of animal models. In neonatal rats, LY233053 selectively blocked NMDA-induced convulsions (ED50 = 14.5 mg/kg i.p.) with a relatively short duration of action (2-4 hr). In pigeons, LY233053 potently antagonized (ED50 = 1.3 mg/kg i.m.) the behavioral suppressant effects of 10 mg/kg of NMDA. However, a dose of 160 mg/kg, i.m., was required to produce phencyclidine-like catalepsy in pigeons. In mice, LY233053 protected against maximal electroshock-induced seizures at lower doses (ED50 = 19.9 mg/kg i.p.) than those that impaired horizontal screen performance (ED50 = 40.9 mg/kg i.p.). Cholinergic and GABAergic neuronal degenerations after striatal infusion of NMDA were prevented by single or multiple i.p. doses of LY233053. In summary, the antagonist activity of LY233053 after systemic administration demonstrates potential therapeutic value in conditions of neuronal cell loss due to NMDA receptor excitotoxicity.

  14. Preliminary Molecular Dynamic Simulations of the Estrogen Receptor Alpha Ligand Binding Domain from Antagonist to Apo

    Directory of Open Access Journals (Sweden)

    Adrian E. Roitberg

    2008-06-01

    Full Text Available Estrogen receptors (ER are known as nuclear receptors. They exist in the cytoplasm of human cells and serves as a DNA binding transcription factor that regulates gene expression. However the estrogen receptor also has additional functions independent of DNA binding. The human estrogen receptor comes in two forms, alpha and beta. This work focuses on the alpha form of the estrogen receptor. The ERα is found in breast cancer cells, ovarian stroma cells, endometrium, and the hypothalamus. It has been suggested that exposure to DDE, a metabolite of DDT, and other pesticides causes conformational changes in the estrogen receptor. Before examining these factors, this work examines the protein unfolding from the antagonist form found in the 3ERT PDB crystal structure. The 3ERT PDB crystal structure has the estrogen receptor bound to the cancer drug 4-hydroxytamoxifen. The 4-hydroxytamoxifen ligand was extracted before the simulation, resulting in new conformational freedom due to absence of van der Waals contacts between the ligand and the receptor. The conformational changes that result expose the binding clef of the co peptide beside Helix 12 of the receptor forming an apo conformation. Two key conformations in the loops at either end of the H12 are produced resulting in the antagonist to apo conformation transformation. The results were produced over a 42ns Molecular Dynamics simulation using the AMBER FF99SB force field.

  15. Structure of the human M2 muscarinic acetylcholine receptor bound to an antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Haga, Kazuko; Kruse, Andrew C.; Asada, Hidetsugu; Yurugi-Kobayashi, Takami; Shiroishi, Mitsunori; Zhang, Cheng; Weis, William I.; Okada, Tetsuji; Kobilka, Brian K.; Haga, Tatsuya; Kobayashi, Takuya (Stanford-MED); (Kyoto); (Gakushuin); (Kyushu)

    2012-03-15

    The parasympathetic branch of the autonomic nervous system regulates the activity of multiple organ systems. Muscarinic receptors are G-protein-coupled receptors that mediate the response to acetylcholine released from parasympathetic nerves. Their role in the unconscious regulation of organ and central nervous system function makes them potential therapeutic targets for a broad spectrum of diseases. The M2 muscarinic acetylcholine receptor (M2 receptor) is essential for the physiological control of cardiovascular function through activation of G-protein-coupled inwardly rectifying potassium channels, and is of particular interest because of its extensive pharmacological characterization with both orthosteric and allosteric ligands. Here we report the structure of the antagonist-bound human M2 receptor, the first human acetylcholine receptor to be characterized structurally, to our knowledge. The antagonist 3-quinuclidinyl-benzilate binds in the middle of a long aqueous channel extending approximately two-thirds through the membrane. The orthosteric binding pocket is formed by amino acids that are identical in all five muscarinic receptor subtypes, and shares structural homology with other functionally unrelated acetylcholine binding proteins from different species. A layer of tyrosine residues forms an aromatic cap restricting dissociation of the bound ligand. A binding site for allosteric ligands has been mapped to residues at the entrance to the binding pocket near this aromatic cap. The structure of the M2 receptor provides insights into the challenges of developing subtype-selective ligands for muscarinic receptors and their propensity for allosteric regulation.

  16. Antagonistas de los receptores glutamatérgicos NMDA en el tratamiento del dolor crónico NMDA glutamatergic receptor antagonists for the management of chronic pain

    Directory of Open Access Journals (Sweden)

    F. Neira

    2004-05-01

    (ketamine, memantine, amantadine, dextromethorphan, methadone is analyzed. Their potential indications include: cancer-related neuropathic pain; postherpetic neuralgia, chronic traumatism; amputation; spine injury; centrally-originated pain secondary to cerebrovascular accident, phantom limb pain; restless legs syndrome, orofacial chronic pain; fibromyalgia and surgery, among others. The effectiveness of ketamine when orally or parenterally administered has been studied in central dysesthesic pain, neuropathic pain in the traumatic cauda equina syndrome, alodynia and hyperalgesia. Dextromethorphan is a non-opiate antitussive and a non-competitive blocker of NMDA receptors. One of its indications is the management of diabetic neuropathy. Methadone binds mainly to opiate receptors mu, but it is also a non-competitive antagonist of NMDA receptors. The use of methadone improves the management of pain since it reduces the development of tolerance to opiates. Memantine is a non-competitive antagonist of NMDA receptors. It reduces the intracortical activation and increases the intracortical inhibition. Experimentally, it has shown antinociceptive effects during the phase secondary to the inflammation induced by the formaline test. It reduces the thermal and mechanical hyperalgesia. NMDA receptor antagonists open new perspectives for the management of neuropathic pain. These drugs are frequently combined with other analgesics, generally acting as coadjuvants. The disparate results obtained with different antagonists used for the same indication confirm the complexity of their mechanism of action, which is not limited to antagonism of NMDA receptors, but it goes much more beyond that.

  17. Aldosterone and aldosterone receptor antagonists in patients with chronic heart failure

    Directory of Open Access Journals (Sweden)

    Nappi J

    2011-06-01

    Full Text Available Jean M Nappi, Adam SiegClinical Pharmacy and Outcome Sciences, South Carolina College of Pharmacy, Medical University of South Carolina Campus, Charleston, SC, USAAbstract: Aldosterone is a mineralocorticoid hormone synthesized by the adrenal glands that has several regulatory functions to help the body maintain normal volume status and electrolyte balance. Studies have shown significantly higher levels of aldosterone secretion in patients with congestive heart failure compared with normal patients. Elevated levels of aldosterone have been shown to elevate blood pressure, cause left ventricular hypertrophy, and promote cardiac fibrosis. An appreciation of the true role of aldosterone in patients with chronic heart failure did not become apparent until the publication of the Randomized Aldactone Evaluation Study. Until recently, the use of aldosterone receptor antagonists has been limited to patients with severe heart failure and patients with heart failure following myocardial infarction. The Eplerenone in Mild Patients Hospitalization and Survival Study in Heart Failure (EMPHASIS-HF study added additional evidence to support the expanded use of aldosterone receptor antagonists in heart failure patients. The results of the EMPHASIS-HF trial showed that patients with mild-to-moderate (New York Heart Association Class II heart failure had reductions in mortality and hospitalizations from the addition of eplerenone to optimal medical therapy. Evidence remains elusive about the exact mechanism by which aldosterone receptor antagonists improve heart failure morbidity and mortality. The benefits of aldosterone receptor antagonist use in heart failure must be weighed against the potential risk of complications, ie, hyperkalemia and, in the case of spironolactone, possible endocrine abnormalities, in particular gynecomastia. With appropriate monitoring, these risks can be minimized. We now have evidence that patients with mild-to-severe symptoms

  18. Evaluation of selective NK(1) receptor antagonist CI-1021 in animal models of inflammatory and neuropathic pain.

    Science.gov (United States)

    Gonzalez, M I; Field, M J; Hughes, J; Singh, L

    2000-08-01

    CI-1021 ([(2-benzofuran)-CH(2)OCO]-(R)-alpha-MeTrp-(S)-NHCH(CH (3))Ph) is a selective and competitive neurokinin-1 (NK(1)) receptor antagonist. This study examines its activity in animal models of inflammatory and neuropathic pain. In mice, CI-1021 (1-30 mg/kg, s.c.) dose dependently blocked the development of the late phase of the formalin response with a minimum effective dose (MED) of 3 mg/kg. Two chemically unrelated NK(1) receptor antagonists, CP-99,994 (3-30 mg/kg) and SR 140333 (1-100 mg/kg), also dose dependently blocked the late phase, with respective MEDs of 3 and 10 mg/kg. PD 156982, a NK(1) receptor antagonist with poor central nervous system penetration, failed to have any effect. However, when administered i. c.v., it selectively blocked the late phase of the formalin response. Chronic constrictive injury (CCI) to a sciatic nerve in the rat induced spontaneous pain, thermal and mechanical hyperalgesia, and cold, dynamic, and static allodynia. CI-1021 (10-100 mg/kg) and morphine (3 mg/kg) blocked all the responses except dynamic allodynia. Carbamazepine (100 mg/kg) was weakly effective against all the responses. Once daily administration of morphine (3 mg/kg, s. c.) in CCI rats led to the development of tolerance within 6 days. Similar administration of CI-1021 (100 mg/kg, s.c.) for up to 10 days did not induce tolerance. Moreover, the morphine tolerance failed to cross-generalize to CI-1021. CI-1021 blocked the CCI-induced hypersensitivity in the guinea pig, with a MED of 0.1 mg/kg, p.o. CI-1021 (10-100 mg/kg, s.c.) did not show sedative/ataxic action in the rat rota-rod test. It is suggested that NK(1) receptor antagonists possess a superior side effect profile to carbamazepine and morphine and may have a therapeutic use for the treatment of inflammatory and neuropathic pain.

  19. Current perspectives on selective dopamine D(3) receptor antagonists as pharmacotherapeutics for addictions and related disorders.

    Science.gov (United States)

    Heidbreder, Christian A; Newman, Amy H

    2010-02-01

    Repeated exposure to drugs of abuse produces long-term molecular and neurochemical changes that may explain the core features of addiction, such as the compulsive seeking and taking of the drug, as well as the risk of relapse. A growing number of new molecular and cellular targets of addictive drugs have been identified, and rapid advances are being made in relating those targets to specific behavioral phenotypes in animal models of addiction. In this context, the pattern of expression of the dopamine (DA) D(3) receptor in the rodent and human brain and changes in this pattern in response to drugs of abuse have contributed primarily to direct research efforts toward the development of selective DA D(3) receptor antagonists. Growing preclinical evidence indicates that these compounds may actually regulate the motivation to self-administer drugs and disrupt drug-associated cue-induced craving. This report will be divided into three parts. First, preclinical evidence in support of the efficacy of selective DA D(3) receptor antagonists in animal models of drug addiction will be reviewed. The effects of mixed DA D(2)/D(3) receptor antagonists will not be discussed here because most of these compounds have low selectivity at the D(3) versus D(2) receptor, and their efficacy profile is related primarily to functional antagonism at D(2) receptors and possibly interactions with other neurotransmitter systems. Second, major advances in medicinal chemistry for the identification and optimization of selective DA D(3) receptor antagonists and partial agonists will be analyzed. Third, translational research from preclinical efficacy studies to so-called proof-of-concept studies for drug addiction indications will be discussed.

  20. Prevention of Stimulant Induced Euphoria with an Opioid Receptor Antagonist

    Science.gov (United States)

    2015-10-01

    peers, deficits in the interactions with peers and superiors, emotional impulsivity that could lead to low self esteem , substance abuse, criminality...Young Adults With ADHD. J Am Acad Child Adolesc Psychiatry. 50(6): p. 543- 53. 12. Zhu, J., et al., Methylphenidate and mu opioid receptor interactions...Sponsor Approved Recorded by / Date 6/14/13 6/14/13 1770201 The blood draw was not completed on Drug Feeling visit after 2 different phlebotomy

  1. Orexin, orexin receptor antagonists and central cardiovascular control

    OpenAIRE

    Carrive, Pascal

    2013-01-01

    Orexin makes an important contribution to the regulation of cardiovascular function. When injected centrally under anesthesia, orexin increases blood pressure, heart rate and sympathetic nerve activity. This is consistent with the location of orexin neurons in the hypothalamus and the distribution of orexin terminals in the central autonomic network. Thus, the two orexin receptors, Ox1R and Ox2R, which have partly overlapping distributions in the brain, are expressed in the sympathetic pregan...

  2. Radiosensitizing Effect of P2X7 Receptor Antagonist on Melanoma in vitro and in vivo.

    Science.gov (United States)

    Tanamachi, Keisuke; Nishino, Keisuke; Mori, Natsuki; Suzuki, Toshihiro; Tanuma, Sei-Ichi; Abe, Ryo; Tsukimoto, Mitsutoshi

    2017-03-24

    Melanoma is highly malignant, and generally exhibits radioresistance, responding poorly to radiation therapy. We previously reported that activation of P2X7, P2Y6, and P2Y12 receptors is involved in the DNA damage response after γ-irradiation of human lung adenocarcinoma A549 cells. However, it is not clear whether these receptors are also involved in the case of melanoma cells, although P2X7 receptor is highly expressed in various cancers, including melanoma. Here, we show that P2X7 receptor antagonist enhances radiation-induced cytotoxicity in B16 melanoma cells in vitro and in vivo. We confirmed that these cells express P2X7 receptor mRNA and exhibit P2X7 receptor-mediated activities, such as ATP-induced pore formation and cytotoxicity. We further examined the radiosensitizing effect of P2X7 receptor antagonist Brilliant Blue G (BBG) in vitro by colony formation assay of B16 cells. γ-Irradiation dose-dependently reduced cell survival, and pretreatment with BBG enhanced the radiation-induced cytotoxicity. BBG pretreatment also decreased the number of DNA repair foci in nuclei, supporting involvement of P2X7 receptor in the DNA damage response. Finally, we investigated the radiosensitizing effect of BBG on B16 melanoma cells inoculated into the hind footpad of C57BL/6 mice. Neither 1 Gy γ-irradiation alone nor BBG alone suppressed the increase of tumor volume, but the combination of irradiation and BBG significantly suppressed tumor growth. Our results suggest that P2X7 receptor antagonist BBG has a radiosensitizing effect in melanoma in vitro and in vivo. BBG, which is used as a food coloring agent, appears to be a promising candidate as a radiosensitizer.

  3. Effects of histamine H(1) receptor antagonists on depressive-like behavior in diabetic mice.

    Science.gov (United States)

    Hirano, Shoko; Miyata, Shigeo; Onodera, Kenji; Kamei, Junzo

    2006-02-01

    We previously reported that streptozotocin-induced diabetic mice showed depressive-like behavior in the tail suspension test. It is well known that the central histaminergic system regulates many physiological functions including emotional behaviors. In this study, we examined the role of the central histaminergic system in the diabetes-induced depressive-like behavior in the mouse tail suspension test. The histamine contents in the hypothalamus were significantly higher in diabetic mice than in non-diabetic mice. The histamine H(1) receptor antagonist chlorpheniramine (1-10 mg/kg, s.c.) dose-dependently and significantly reduced the duration of immobility in both non-diabetic and diabetic mice. In contrast, the selective histamine H(1) receptor antagonists epinastine (0.03-0.3 microg/mouse, i.c.v.) and cetirizine (0.01-0.1 microg/mouse, i.c.v.) dose-dependently and significantly suppressed the duration of immobility in diabetic mice, but not in non-diabetic mice. Spontaneous locomotor activity was not affected by histamine H(1) receptor antagonists in either non-diabetic or diabetic mice. In addition, the number and affinity of histamine H(1) receptors in the frontal cortex were not affected by diabetes. In conclusion, we suggest that the altered neuronal system mediated by the activation of histamine H(1) receptors is involved, at least in part, in the depressive-like behavior seen in diabetic mice.

  4. Dopamine D3 receptor antagonists as potential therapeutics for the treatment of neurological diseases

    Directory of Open Access Journals (Sweden)

    Samuele Maramai

    2016-10-01

    Full Text Available D3 receptors represent a major focus of current drug design and development of therapeutics for dopamine-related pathological states. Their close homology with the D2 receptor subtype makes the development of D3 selective antagonists a challenging task. In this review, we explore the relevance and therapeutic utility of D3 antagonists or partial agonists endowed with multireceptor affinity profile in the field of central nervous system disorders such as schizophrenia and drug abuse. In fact, the peculiar distribution and low brain abundance of D3 receptors make them a valuable target for the development of drugs devoid of motor side effects classically elicited by D2 antagonists. Recent research efforts were devoted to the conception of chemical templates possibly endowed with a multi-target profile, especially with regards to other G-protein-coupled receptors (GPCRs.A comprehensive overview of the recent literature in the field is herein provided. In particular, the evolution of the chemical templates has been tracked, according to the growing advancements in both the structural information and the refinement of the key pharmacophoric elements.The receptor/multireceptor affinity and functional profiles for the examined compounds has been covered, together with their most significant pharmacological applications.

  5. Rodent antinociception following acute treatment with different histamine receptor agonists and antagonists.

    Science.gov (United States)

    Farzin, Davood; Asghari, Ladan; Nowrouzi, Mahvash

    2002-06-01

    The effects of different histamine receptor agonists and antagonists on the nociceptive threshold were investigated in mice by two different kinds of noxious stimuli: thermal (hot plate) and chemical (acetic acid-induced abdominal writhing). Intracerebroventricular (icv) injection of the histamine H(1) receptor agonist, HTMT (6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide) (50 microg/mouse), produced a hypernociception in the hot plate and writhing tests. Conversely, intraperitoneal (ip) injection of dexchlorpheniramine (30 and 40 mg/kg) and diphenhydramine (20 and 40 mg/kg) increased the pain threshold in both tests. The histamine H(2) receptor agonist, dimaprit (50 and 100 microg/mouse icv), or antagonist, ranitidine (50 and 100 microg/mouse icv), raised the pain threshold in both hot plate and writhing tests. In the mouse hot plate test, the histamine H(3) receptor agonist, imetit (50 mg/kg ip), reduced the pain threshold, while the histamine H(3) receptor antagonist, thioperamide (10 and 20 mg/kg ip), produced an antinociception. The hypernociceptive effects of HTMT and imetit were antagonized by dexchlorpheniramine (20 mg/kg ip) and thioperamide (5 mg/kg ip), respectively. The results suggest that histaminergic mechanisms may be involved in the modulation of nociceptive stimuli.

  6. Serotonin (5-HT3 receptor antagonists for the reduction of symptoms of low anterior resection syndrome

    Directory of Open Access Journals (Sweden)

    Itagaki R

    2014-03-01

    Full Text Available Ryohei Itagaki, Keiji Koda, Masato Yamazaki, Kiyohiko Shuto, Chihiro Kosugi, Atsushi Hirano, Hidehito Arimitsu, Risa Shiragami, Yukino Yoshimura, Masato Suzuki Department of Surgery, Teikyo University Chiba Medical Center, Anesaki, Ichihara, Chiba, Japan Purpose: Serotonin (5-hydroxytryptamine [5-HT]3 receptor antagonists are effective for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D, in which exaggerated intestinal/colonic hypermotility is often observed. Recent studies have suggested that the motility disorder, especially spastic hypermotility, seen in the neorectum following sphincter-preserving operations for rectal cancer may be the basis of the postoperative defecatory malfunction seen in these patients. We investigated the efficacy of 5-HT3 receptor antagonists in patients suffering from severe low anterior resection syndrome. Patients and methods: A total of 25 male patients with complaints of uncontrollable urgency or fecal incontinence following sphincter-preserving operations were enrolled in this study. Defecatory status, assessed on the basis of incontinence score (0–20, urgency grade (0–3, and number of toilet visits per day, was evaluated using a questionnaire before and 1 month after the administration of the 5-HT3 antagonist ramosetron. Results: All the parameters assessed improved significantly after taking ramosetron for 1 month. The effect was more prominent in cases whose anastomotic line was lower, ie, inside the anal canal. Defecatory function was better in patients who commenced ramosetron therapy within 6 months postoperatively, as compared to those who were not prescribed ramosetron for more than 7 months postoperatively. Conclusion: These results suggest that 5-HT3 antagonists are effective for the treatment of low anterior resection syndrome, as in diarrhea-predominant irritable bowel syndrome. The improvement in symptoms is not merely time dependent, but it is related to treatment with 5

  7. Neurokinin-1 receptor antagonists for chemotherapy-induced nausea and vomiting.

    Science.gov (United States)

    Aziz, Fahad

    2012-07-01

    Chemotherapy can be a life-prolonging treatment for many cancer patients, but it is often associated with profound nausea and vomiting that is so distressing that patients may delay or decline treatment to avoid these side effects. The discovery of several NK1 receptor antagonists is a big revolution to dealt this problem. NK1 receptor antagonists prevent both acute and delayed chemotherapy-induced nausea and vomiting (CINV). These agents act centrally at NK-1 receptors in vomiting centers within the central nervous system to block their activation by substance P released as an unwanted consequence of chemotherapy. By controlling nausea and vomiting, these agents help improve patients' daily living and their ability to complete multiple cycles of chemotherapy. They are effective for both moderately and highly emetogenic chemotherapy regimens. Their use might be associated with increased infection rates; however, additional appraisal of specific data from RCTs is needed.

  8. Therapeutic Opportunities for Caffeine and A2A Receptor Antagonists in Retinal Diseases.

    Science.gov (United States)

    Boia, Raquel; Ambrósio, António Francisco; Santiago, Ana Raquel

    2016-01-01

    Caffeine, the major component of coffee, is the most consumed psychostimulant in the world. Caffeine is an adenosine analog and acts as a nonselective adenosine receptor antagonist. The majority of the effects of caffeine are mainly mediated by the blockade of adenosine receptors, and the proved neuroprotective effects of caffeine in brain disorders have been mimicked by the blockade of adenosine A2A receptor (A2AR). A growing body of evidence demonstrates that microglia-mediated neuroinflammation plays a key role in the pathophysiology of brain and retinal diseases. Moreover, the control of microglia reactivity by blocking A2AR has been proposed to be the mechanism underlying the observed protective effects of caffeine. Hence, it is conceivable that caffeine and A2AR antagonists offer therapeutic value for the treatment of retinal diseases, mainly those involving microglia-mediated neuroinflammation.

  9. Novel histamine H3-receptor antagonists and partial agonists with a non-aminergic structure

    OpenAIRE

    Nickel, Tobias; Bauer, Ulrich; Schlicker, Eberhard; Kathmann, Markus; Göthert, Manfred; Sasse, Astrid; Stark, Holger; Schunack, Walter

    2001-01-01

    We determined the affinities of eight novel histamine H3-receptor ligands (ethers and carbamates) for H3-receptor binding sites and their agonistic/antagonistic effects in two functional H3-receptor models. The compounds differ from histamine in that the ethylamine chain is replaced by a propyloxy chain; in the three ethers mentioned below (FUB 335, 373 and 407), R is n-pentyl, 3-methylbutyl and 3,3-dimethylbutyl, respectively.The compounds monophasically inhibited [3H]-Nα-methylhistamine bin...

  10. Blonanserin, an antipsychotic and dopamine D₂/D₃receptor antagonist, and ameliorated alcohol dependence.

    Science.gov (United States)

    Takaki, Manabu; Ujike, Hiroshi

    2013-01-01

    Blonanserin (BNS) is used for treatment of both positive and negative symptoms of schizophrenia in Japan and Korea. Because BNS has weak α1 receptor blocking activities and is almost devoid of histamine H1 and muscarinic M1 antagonist activity, BNS is better tolerated than other atypical antipsychotics. A high degree of D₃ receptor blockage is reported to be predictive of drug abuse and alcoholism, and BNS has strong D₃ receptor antagonism. Thus, BNS may be useful in the treatment of alcoholism. We present a case in which BNS ameliorated alcohol dependence.

  11. Dopamine receptor ligands. Part 18: (1) modification of the structural skeleton of indolobenzazecine-type dopamine receptor antagonists.

    Science.gov (United States)

    Robaa, Dina; Enzensperger, Christoph; Abul Azm, Shams El Din; El Khawass, El Sayeda; El Sayed, Ola; Lehmann, Jochen

    2010-03-25

    On the basis of the D(1/5)-selective dopamine antagonist LE 300 (1), an indolo[3,2-f]benzazecine derivative, we changed the annulation pattern of the heterocycles. The target compounds represent novel heterocyclic ring systems. The most constrained indolo[4,3a,3-ef]benzazecine 2 was inactive, but the indolo[4,3a,3-fg]benzazacycloundecene 3 showed antagonistic properties (functional Ca(2+) assay) with nanomolar affinities (radioligand binding) for all dopamine receptor subtypes, whereas the indolo[2,3-f]benzazecine 4 displayed a selectivity profile similar to 3 but with decreased affinities.

  12. Discovery of new SCH 39166 analogs as potent and selective dopamine D1 receptor antagonists.

    Science.gov (United States)

    Qiang, Li; Sasikumar, T K; Burnett, Duane A; Su, Jing; Tang, Haiqun; Ye, Yuanzan; Mazzola, Robert D; Zhu, Zhaoning; McKittrick, Brian A; Greenlee, William J; Fawzi, Ahmad; Smith, Michelle; Zhang, Hongtao; Lachowicz, Jean E

    2010-02-01

    A series of novel dopamine D(1) antagonists derived from functionalization of the D-ring of SCH 39166 were prepared. A number of these compounds displayed subnanomolar D(1) activity and more than 1000-fold selectivity over D(2). We found C-3 derivatization afforded compounds with superior overall profile in comparison to the C-2 and C-4 derivatization. A number of highly potent D(1) antagonists were discovered which have excellent selectivity over other dopamine receptors and improved PK profile compared to SCH 39166.

  13. Chemogenomic discovery of allosteric antagonists at the GPRC6A receptor

    DEFF Research Database (Denmark)

    Gloriam, David E.; Wellendorph, Petrine; Johansen, Lars Dan;

    2011-01-01

    and pharmacological character: (1) chemogenomic lead identification through the first, to our knowledge, ligand inference between two different GPCR families, Families A and C; and (2) the discovery of the most selective GPRC6A allosteric antagonists discovered to date. The unprecedented inference of...... pharmacological activity across GPCR families provides proof-of-concept for in silico approaches against Family C targets based on Family A templates, greatly expanding the prospects of successful drug design and discovery. The antagonists were tested against a panel of seven Family A and C G protein-coupled receptors...

  14. Identification of clinical candidates from the benzazepine class of histamine H3 receptor antagonists.

    Science.gov (United States)

    Wilson, David M; Apps, James; Bailey, Nicholas; Bamford, Mark J; Beresford, Isabel J; Brackenborough, Kim; Briggs, Michael A; Brough, Stephen; Calver, Andrew R; Crook, Barry; Davis, Rebecca K; Davis, Robert P; Davis, Susannah; Dean, David K; Harris, Leanne; Heslop, Teresa; Holland, Vicky; Jeffrey, Phillip; Panchal, Terrance A; Parr, Christopher A; Quashie, Nigel; Schogger, Joanne; Sehmi, Sanjeet S; Stean, Tania O; Steadman, Jon G A; Trail, Brenda; Wald, Jeffrey; Worby, Angela; Takle, Andrew K; Witherington, Jason; Medhurst, Andrew D

    2013-12-15

    This Letter describes the discovery of GSK189254 and GSK239512 that were progressed as clinical candidates to explore the potential of H3 receptor antagonists as novel therapies for the treatment of Alzheimer's disease and other dementias. By carefully controlling the physicochemical properties of the benzazepine series and through the implementation of an aggressive and innovative screening strategy that employed high throughput in vivo assays to efficiently triage compounds, the medicinal chemistry effort was able to rapidly progress the benzazepine class of H3 antagonists through to the identification of clinical candidates with robust in vivo efficacy and excellent developability properties.

  15. Adenosine A2A receptor antagonists exert motor and neuroprotective effects by distinct cellular mechanisms

    OpenAIRE

    Yu, Liqun; Shen, Hai-Ying; Coelho, Joana E.; Araújo, Inês M.; HUANG, QING-YUAN; Day, Yuan-Ji; Rebola, Nelson; Canas, Paula M.; Rapp, Erica Kirsten; Ferrara, Jarrod; Taylor, Darcie; Müller, Christa E.; Linden, Joel; Cunha, Rodrigo A.; Chen, Jiang-Fan

    2008-01-01

    To investigate whether the motor and neuroprotective effects of adenosine A2A receptor (A2AR) antagonists are mediated by distinct cell types in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease.We used the forebrain A2AR knock-out mice coupled with flow cytometric analyses and intracerebroventricular injection to determine the contribution of A2ARs in forebrain neurons and glial cells to A2AR antagonist-mediated motor and neuroprotective effects.The selecti...

  16. Serotonin receptor antagonists discriminate between PKA- and PKC-mediated plasticity in aplysia sensory neurons.

    Science.gov (United States)

    Dumitriu, Bogdan; Cohen, Jonathan E; Wan, Qin; Negroiu, Andreea M; Abrams, Thomas W

    2006-04-01

    Highly selective serotonin (5-hydroxytryptamine, 5-HT) receptor antagonists developed for mammals are ineffective in Aplysia due to the evolutionary divergence of neurotransmitter receptors and because the higher ionic strength of physiological saline for marine invertebrates reduces antagonist affinity. It has therefore been difficult to identify antagonists that specifically block individual signaling cascades initiated by 5-HT. We studied two broad-spectrum 5-HT receptor antagonists that have been characterized biochemically in Aplysia CNS: methiothepin and spiperone. Methiothepin is highly effective in inhibiting adenylyl cyclase (AC)-coupled 5-HT receptors in Aplysia. Spiperone, which blocks phospholipase C (PLC)-coupled 5-HT receptors in mammals, does not block AC-coupled 5-HT receptors in Aplysia. In electrophysiological studies, we explored whether methiothepin and spiperone can be used in parallel to distinguish between the AC-cAMP and PLC-protein kinase C (PKC) modulatory cascades that are initiated by 5-HT. 5-HT-induced broadening of the sensory neuron action potential in the presence of tetraethylammonium/nifedipine, which is mediated by modulation of the S-K+ currents, was used an assay for the AC-cAMP cascade. Spike broadening initiated by 5 microM 5-HT was unaffected by 100 microM spiperone, whereas it was effectively blocked by 100 microM methiothepin. Facilitation of highly depressed sensory neuron-to-motor neuron synapses by 5-HT was used as an assay for the PLC-PKC cascade. Spiperone completely blocked facilitation of highly depressed synapses by 5 microM 5-HT. In contrast, methiothepin produced a modest, nonsignificant, reduction in the facilitation of depressed synapses. Interestingly, these experiments revealed that the PLC-PKC cascade undergoes desensitization during exposure to 5-HT.

  17. Cheiradone: a vascular endothelial cell growth factor receptor antagonist

    Directory of Open Access Journals (Sweden)

    Ahmed Nessar

    2008-01-01

    Full Text Available Abstract Background Angiogenesis, the growth of new blood vessels from the pre-existing vasculature is associated with physiological (for example wound healing and pathological conditions (tumour development. Vascular endothelial growth factor (VEGF, fibroblast growth factor-2 (FGF-2 and epidermal growth factor (EGF are the major angiogenic regulators. We have identified a natural product (cheiradone isolated from a Euphorbia species which inhibited in vivo and in vitro VEGF- stimulated angiogenesis but had no effect on FGF-2 or EGF activity. Two primary cultures, bovine aortic and human dermal endothelial cells were used in in vitro (proliferation, wound healing, invasion in Matrigel and tube formation and in vivo (the chick chorioallantoic membrane models of angiogenesis in the presence of growth factors and cheiradone. In all cases, the concentration of cheiradone which caused 50% inhibition (IC50 was determined. The effect of cheiradone on the binding of growth factors to their receptors was also investigated. Results Cheiradone inhibited all stages of VEGF-induced angiogenesis with IC50 values in the range 5.20–7.50 μM but did not inhibit FGF-2 or EGF-induced angiogenesis. It also inhibited VEGF binding to VEGF receptor-1 and 2 with IC50 values of 2.9 and 0.61 μM respectively. Conclusion Cheiradone inhibited VEGF-induced angiogenesis by binding to VEGF receptors -1 and -2 and may be a useful investigative tool to study the specific contribution of VEGF to angiogenesis and may have therapeutic potential.

  18. Species differences in the effects of the κ-opioid receptor antagonist zyklophin.

    Science.gov (United States)

    Sirohi, Sunil; Aldrich, Jane V; Walker, Brendan M

    2016-03-01

    We have shown that dysregulation of the dynorphin/kappa-opioid receptor (DYN/KOR) system contributes to escalated alcohol self-administration in alcohol dependence and that KOR antagonists with extended durations of action selectively reduce escalated alcohol consumption in alcohol-dependent animals. As KOR antagonism has gained widespread attention as a potential therapeutic target to treat alcoholism and multiple neuropsychiatric disorders, we tested the effect of zyklophin (a short-acting KOR antagonist) on escalated alcohol self-administration in rats made alcohol-dependent using intermittent alcohol vapor exposure. Following dependence induction, zyklophin was infused centrally prior to alcohol self-administration sessions and locomotor activity tests during acute withdrawal. Zyklophin did not impact alcohol self-administration or locomotor activity in either exposure condition. To investigate the neurobiological basis of this atypical effect for a KOR antagonist, we utilized a κ-, μ-, and δ-opioid receptor agonist-stimulated GTPyS coupling assay to examine the opioid receptor specificity of zyklophin in the rat brain and mouse brain. In rats, zyklophin did not affect U50488-, DAMGO-, or DADLE-stimulated GTPyS coupling, whereas the prototypical KOR antagonist nor-binaltorphimine (norBNI) attenuated U50488-induced stimulation in the rat brain tissue at concentrations that did not impact μ- and δ-receptor function. To reconcile the discrepancy between the present rat data and published mouse data, comparable GTPyS assays were conducted using mouse brain tissue; zyklophin effects were consistent with KOR antagonism in mice. Moreover, at higher concentrations, zyklophin exhibited agonist properties in rat and mouse brains. These results identify species differences in zyklophin efficacy that, given the rising interest in the development of short-duration KOR antagonists, should provide valuable information for therapeutic development efforts.

  19. Cannabinoid-1 receptor antagonists in type-2 diabetes.

    Science.gov (United States)

    Scheen, André J

    2007-12-01

    Type-2 diabetes is closely related to abdominal obesity and is generally associated with other cardiometabolic risk factors, resulting in a risk of major cardiovascular disease. Several animal and human observations suggest that the endocannabinoid system is over-active in the presence of abdominal obesity and/or diabetes. Both central and peripheral endocannabinoid actions, via the activation of CB1 receptors, promote weight gain and associated metabolic changes. Rimonabant, the first selective CB(1) receptor blocker in clinical use, has been shown to reduce body weight, waist circumference, triglycerides, blood pressure, insulin resistance index and C-reactive protein levels, and to increase high-density lipoprotein (HDL) cholesterol and adiponectin concentrations in both non-diabetic and diabetic overweight/obese patients. In addition, a 0.5-0.7% reduction in HbA1c levels was observed in metformin- or sulphonylurea-treated patients with type-2 diabetes and in drug-naïve diabetic patients. Almost half of the metabolic changes, including HbA1c reduction, could not be explained by weight loss, suggesting that there are direct peripheral effects. Rimonabant was generally well-tolerated, and the safety profile was similar in diabetic and non-diabetic patients, with a higher incidence of depressed mood disorders, nausea and dizziness. In conclusion, the potential role of rimonabant in overweight/obese patients with type-2 diabetes and at high risk of cardiovascular disease deserves much consideration.

  20. Effect of dopamine and serotonin receptor antagonists on fencamfamine-induced abolition of latent inhibition.

    Science.gov (United States)

    de Aguiar, Cilene Rejane Ramos Alves; de Aguiar, Marlison José Lima; DeLucia, Roberto; Silva, Maria Teresa Araujo

    2013-01-05

    The purpose of this investigation was to verify the role of dopamine and serotonin receptors in the effect of fencamfamine (FCF) on latent inhibition. FCF is a psychomotor stimulant with an indirect dopaminergic action. Latent inhibition is a model of attention. Latent inhibition is blocked by dopaminergic agents and facilitated by dopamine receptor agonists. FCF has been shown to abolish latent inhibition. The serotonergic system may also participate in the neurochemical mediation of latent inhibition. The selective dopamine D(1) receptor antagonist SCH 23390 (7-chloro-3-methyl-1-phenyl-1,2,4,5-tetrahydro-3-benzazepin-8-ol), D(2) receptor antagonists pimozide (PIM) and methoclopramide (METH), and serotonin 5-HT(2A/C) receptor antagonist ritanserin (RIT) were used in the present study. Latent inhibition was evaluated using a conditioned emotional response procedure. Male Wistar rats that were water-restricted were subjected to a three-phase procedure: preexposure to a tone, tone-shock conditioning, and a test of the effect of the tone on licking frequency. All of the drugs were administered before the preexposure and conditioning phases. The results showed that FCF abolished latent inhibition, and this effect was clearly antagonized by PIM and METH and moderately attenuated by SCH 23390. At the doses used in the present study, RIT pretreatment did not affect latent inhibition and did not eliminate the effect of FCF, suggesting that the FCF-induced abolition of latent inhibition is not mediated by serotonin 5-HT(2A/C) receptors. These results suggest that the effect of FCF on latent inhibition is predominantly related to dopamine D(2) receptors and that dopamine D(2) receptors participate in attention processes.

  1. Opioid Receptor Antagonists in the Treatment of Alcoholism.

    Science.gov (United States)

    Serecigni, Josep Guardia

    2015-09-29

    Objetivos: A partir de los recientes progresos en la farmacoterapia del alcoholismo, hemos efectuado una revisión sobre los fármacos antagonistas de los receptores opioides, que tienen aprobada la indicación para el tratamiento del alcoholismo, como son naltrexona y nalmefeno. Metodología: Hemos revisado más de 100 publicaciones sobre péptidos y receptores opioides, el efecto de los fármacos antagonistas de los receptores opioides sobre el consumo de alcohol, tanto en animales como en humanos, tanto en el laboratorio como para el tratamiento del alcoholismo. También se describen las características farmacológicas de naltrexona y de nalmefeno y su utilidad en la práctica clínica. Resultados: Múltiples evidencias han demostrado la eficacia de naltrexona y nalmefeno para reducir el consumo de alcohol, tanto en animales de laboratorio como también en personas estudiadas en situación de bar experimental, aunque debido al diferente perfil receptorial, nalmefeno ha sido relacionado con una mayor eficacia para la reducción del consumo de alcohol, en ratas que presentan dependencia del alcohol. Además, un gran número de ensayos clínicos controlados han demostrado la eficacia de naltrexona para la prevención de recaídas, en personas que presentan un trastorno por dependencia del alcohol. Ensayos clínicos controlados recientes han demostrado la eficacia de nalmefeno “a demanda” para reducir el consumo de alcohol, en personas que presentan un trastorno por dependencia del alcohol de baja gravedad. Conclusiones: Tanto naltrexona como nalmefeno han demostrado ser fármacos seguros, bien tolerados, de manejo sencillo, y eficaces para el tratamiento del trastorno por dependencia del alcohol, (actualmente llamado trastorno por consumo de alcohol). A partir de recientes ensayos clínicos controlados se ha comprobado que nalmefeno produce una reducción significativa del consumo de alcohol, lo cual supone un nuevo objetivo que amplía las posibilidades de

  2. Growth Hormone Receptor Antagonist Treatment Reduces Exercise Performance in Young Males

    DEFF Research Database (Denmark)

    Goto, K.; Doessing, S.; Nielsen, R.H.

    2009-01-01

    period, they exercised to determine exercise performance and hormonal and metabolic responses. Participants: Twenty healthy males participated in the study. Intervention: Subjects were treated with the GHR antagonist (n = 10; 10 mg/d) or placebo (n = 10). After the treatment period, they performed...... a maximal oxygen uptake ((V) over dotO(2max)) test and a prolonged exercise test, consisting of 60 min of submaximal cycling followed by exercise to fatigue at 90% of (V) over dotO(2max). Main Outcome Measures: (V) over dotO(2max) was measured before and after the treatment period. Hormonal and metabolic......Context: The effects of GH on exercise performance remain unclear. Objective: The aim of the study was to examine the effects of GH receptor (GHR) antagonist treatment on exercise performance. Design: Subjects were treated with the GHR antagonist pegvisomant or placebo for 16 d. After the treatment...

  3. Effects of Proton Pump Inhibitors and H2 Receptor Antagonists on the Ileum Motility

    Directory of Open Access Journals (Sweden)

    Atilla Kurt

    2011-01-01

    Full Text Available Objectives. To investigate the effects of proton pump inhibitors (PPIs and H2 receptor antagonists on ileum motility in rats with peritonitis and compare changes with control group rats. Methods. Peritonitis was induced by cecal ligation and puncture in 8 rats. Another of 8 rats underwent a sham operation and were accepted as controls. Twenty-four hours later after the operation, the rats were killed, and their ileum smooth muscle was excised and placed in circular muscle direction in a 10 mL organ bath. Changes in amplitude and frequency of contractions were analyzed before and after PPIs and H2 receptor blockers. Results. PPI agents decreased the motility in a dose-dependent manner in ileum in both control and intraabdominal sepsis groups. While famotidine had no significant effect on ileum motility, ranitidine and nizatidine enhanced motility in ileum in both control and intraabdominal sepsis groups. This excitatory effect of H2 receptor antagonists and inhibitor effects of PPIs were significantly high in control group when compared to the peritonitis group. The inhibitor effect of pantoprazole on ileum motility was significantly higher than the other two PPI agents. Conclusions. It was concluded that H2 receptor antagonists may be more effective than PPIs for recovering the bowel motility in the intraabdominal sepsis situation.

  4. The 5-HT2A receptor antagonist M100907 produces antiparkinsonian effects and decreases striatal glutamate

    Directory of Open Access Journals (Sweden)

    Twum eAnsah

    2011-06-01

    Full Text Available 5-HT plays a regulatory role in voluntary movements of the basal ganglia and have a major impact on disorders of the basal ganglia such as Parkinson’s disease (PD. Clinical studies have suggested that 5-HT2 receptor antagonists may be useful in the treatment of the motor symptoms of PD. We hypothesized that 5-HT2A receptor antagonists may restore motor function by regulating glutamatergic activity in the striatum. Mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP exhibited decreased performance on the beam-walking apparatus. Peripheral administration of the 5-HT2A receptor antagonist M100907 improved performance of MPTP-treated mice on the beam-walking apparatus. In vivo microdialysis revealed an increase in striatal extracellular glutamate in MPTP-treated mice and local perfusion of M100907 into the dorsal striatum significantly decreased extracellular glutamate levels in saline and MPTP-treated mice. Our studies suggest that blockade of 5-HT2A receptors may represent a novel therapeutic target for the motor symptoms of Parkinson’s disease.

  5. AM-37 and ST-36 Are Small Molecule Bombesin Receptor Antagonists.

    Science.gov (United States)

    Moody, Terry W; Tashakkori, Nicole; Mantey, Samuel A; Moreno, Paola; Ramos-Alvarez, Irene; Leopoldo, Marcello; Jensen, Robert T

    2017-01-01

    While peptide antagonists for the gastrin-releasing peptide receptor (BB2R), neuromedin B receptor (BB1R), and bombesin (BB) receptor subtype-3 (BRS-3) exist, there is a need to develop non-peptide small molecule inhibitors for all three BBR. The BB agonist (BA)1 binds with high affinity to the BB1R, BB2R, and BRS-3. In this communication, small molecule BBR antagonists were evaluated using human lung cancer cells. AM-37 and ST-36 inhibited binding to human BB1R, BB2R, and BRS-3 with similar affinity (Ki = 1.4-10.8 µM). AM-13 and AM-14 were approximately an order of magnitude less potent than AM-37 and ST-36. The ability of BA1 to elevate cytosolic Ca(2+) in human lung cancer cells transfected with BB1R, BB2R, and BRS-3 was antagonized by AM-37 and ST-36. BA1 increased tyrosine phosphorylation of the EGFR and ERK in lung cancer cells, which was blocked by AM-37 and ST-36. AM-37 and ST-36 reduced the growth of lung cancer cells that have BBR. The results indicate that AM-37 and ST-36 function as small molecule BB receptor antagonists.

  6. Novel Alexa Fluor-488 labeled antagonist of the A(2A) adenosine receptor: Application to a fluorescence polarization-based receptor binding assay.

    Science.gov (United States)

    Kecskés, Miklós; Kumar, T Santhosh; Yoo, Lena; Gao, Zhan-Guo; Jacobson, Kenneth A

    2010-08-15

    Fluorescence polarization (FP) assay has many advantages over the traditional radioreceptor binding studies. We developed an A(2A) adenosine receptor (AR) FP assay using a newly synthesized fluorescent antagonist of the A(2A)AR (MRS5346), a pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine derivative conjugated to the fluorescent dye Alexa Fluor-488. MRS5346 displayed a K(i) value of 111+/-16nM in radioligand binding using [(3)H]CGS21680 and membranes prepared from HEK293 cells stably expressing the human A(2A)AR. In a cyclic AMP functional assay, MRS5346 was shown to be an A(2A)AR antagonist. MRS5346 did not show any effect on A(1) and A(3) ARs in binding or the A(2B)AR in a cyclic AMP assay at 10microM. Its suitability as a fluorescent tracer was indicated in an initial observation of an FP signal following A(2A)AR binding. The FP signal was optimal with 20nM MRS5346 and 150microg protein/mL HEK293 membranes. The association and dissociation kinetic parameters were readily determined using this FP assay. The K(d) value of MRS5346 calculated from kinetic parameters was 16.5+/-4.7nM. In FP competition binding experiments using MRS5346 as a tracer, K(i) values of known AR agonists and antagonists consistently agreed with K(i) values from radioligand binding. Thus, this FP assay, which eliminates using radioisotopes, appears to be appropriate for both routine receptor binding and high-throughput screening with respect to speed of analysis, displaceable signal and precision. The approach used in the present study could be generally applicable to other GPCRs.

  7. Classification of 5-HT1A receptor agonists and antagonists using GA-SVM method

    Institute of Scientific and Technical Information of China (English)

    Xue-lian ZHU; Hai-yan CAI; Zhi-jian XU; Yong WANG; He-yao WANG; Ao ZHANG; Wei-liang ZHU

    2011-01-01

    Aim:To construct a reliable computational model for the classification of agonists and antagonists of 5-HT1A receptor.Methods:Support vector machine (SVM),a well-known machine learning method,was employed to build a prediction model,and genetic algorithm (GA) was used to select the most relevant descriptors and to optimize two important parameters,C and r of the SVM model.The overall dataset used in this study comprised 284 ligands of the 5-HT1A receptor with diverse structures reported in the literatures.Results:A SVM model was successfully developed that could be used to predict the probability of a ligand being an agonist or antagonist of the 5-HT1A receptor.The predictive accuracy for training and test sets was 0.942 and 0.865,respectively.For compounds with probability estimate higher than 0.7,the predictive accuracy of the model for training and test sets was 0.954 and 0.927,respectively.To further validate our model,the receiver operating characteristic (ROC) curve was plotted,and the Area-Under-the-ROC-Curve (AUC) value was calculated to be 0.883 for training set and 0.906 for test set.Conclusion:A reliable SVM model was successfully developed that could effectively distinguish agonists and antagonists among the ligands of the 5-HT1A receptor.To our knowledge,this is the first effort for the classification of 5-HT1A receptor agonists and antagonists based on a diverse dataset.This method may be used to classify the ligands of other members of the GPCR family.

  8. Opioid receptor antagonists increase [Ca2+]i in rat arterial smooth muscle cells in hemorrhagic shock

    Institute of Scientific and Technical Information of China (English)

    Li KAI; Zhong-feng WANG; Yu-liang SHI; Liang-ming LIU; De-yao HU

    2004-01-01

    AIM: To examine the effects of opioid receptor antagonists and norepinephrine on intracellular free Ca2+ concentration ([Ca2+]i) in mesenteric arterial (MA) smooth muscle cells (SMC) isolated from normal and hemorrhagic shocked rats in the vascular hyporesponse stage. METHODS: The rat model of hemorrhagic shock was made by withdrawing blood to decrease the artery mean blood pressure to 3.73-4.26 kPa and keeping at the level for 3 h.[Ca2+]i of vascular smooth muscle cells (VSMC) were detected by the laser scan confocal microscopy. RESULTS:In the hyporesponse VMSC of rats in hemorrhagic shock, selective δ-, κ-, and μ-opioid receptor antagonists (naltrindole, nor-binaltorphimine, and β-funaltrexamine, 100 nmol/L) as well as norepinephrine 5 μmol/L significantly increased [Ca2+]i by 47 %±13 %, 37 %±14 %, 33 %±10 %, and 54 %±17 %, respectively, although their effects were lower than those in the normal rat cells (the increased values were 148 %±54 %, 130 %±44 %, 63 %±17 %and 110 %±38 %, respectively); and the norepinephrine-induced increase in [Ca2+]i was further augmented by three δ-, κ-, and μ-opioid receptor antagonists (50 nmol/L, respectively) application (from 52 %± 16 % to 99 %±29 %,146 %±54 % and 137 %±47 %, respectively). CONCLUSION: The disorder of [Ca2+]i regulation induced by hemorrhagic shock was mediated by opioid receptor and α-adrenoceptor, which may be partly responsible for the vascular hyporesponse, and the opioid receptor antagonists improved the response of resistance arteries to vascular stimulants in decompensatory stage of hemorrhagic shock.

  9. The neurokinin 1 receptor antagonist, ezlopitant, reduces appetitive responding for sucrose and ethanol.

    Directory of Open Access Journals (Sweden)

    Pia Steensland

    Full Text Available BACKGROUND: The current obesity epidemic is thought to be partly driven by over-consumption of sugar-sweetened diets and soft drinks. Loss-of-control over eating and addiction to drugs of abuse share overlapping brain mechanisms including changes in motivational drive, such that stimuli that are often no longer 'liked' are still intensely 'wanted' [7], . The neurokinin 1 (NK1 receptor system has been implicated in both learned appetitive behaviors and addiction to alcohol and opioids; however, its role in natural reward seeking remains unknown. METHODOLOGY/PRINCIPAL FINDINGS: We sought to determine whether the NK1-receptor system plays a role in the reinforcing properties of sucrose using a novel selective and clinically safe NK1-receptor antagonist, ezlopitant (CJ-11,974, in three animal models of sucrose consumption and seeking. Furthermore, we compared the effect of ezlopitant on ethanol consumption and seeking in rodents. The NK1-receptor antagonist, ezlopitant decreased appetitive responding for sucrose more potently than for ethanol using an operant self-administration protocol without affecting general locomotor activity. To further evaluate the selectivity of the NK1-receptor antagonist in decreasing consumption of sweetened solutions, we compared the effects of ezlopitant on water, saccharin-, and sodium chloride (NaCl solution consumption. Ezlopitant decreased intake of saccharin but had no effect on water or salty solution consumption. CONCLUSIONS/SIGNIFICANCE: The present study indicates that the NK1-receptor may be a part of a common pathway regulating the self-administration, motivational and reinforcing aspects of sweetened solutions, regardless of caloric value, and those of substances of abuse. Additionally, these results indicate that the NK1-receptor system may serve as a therapeutic target for obesity induced by over-consumption of natural reinforcers.

  10. 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.

  11. A rational approach to the design and synthesis of a new bradykinin B(1) receptor antagonist.

    Science.gov (United States)

    Bedos, P; Amblard, M; Subra, G; Dodey, P; Luccarini, J M; Paquet, J L; Pruneau, D; Aumelas, A; Martinez, J

    2000-06-15

    We have previously synthesized a potent and selective B(1) bradykinin receptor antagonist, JMV1645 (H-Lys-Arg-Pro-Hyp-Gly-Igl-Ser-D-BT-OH), containing a dipeptide mimetic ((3S)-amino-5-carbonylmethyl-2,3-dihydro-1, 5-benzothiazepin-4(5H)-one (D-BT) moiety) at the C-terminal. Analogues of this potent B(1) bradykinin receptor antagonist in which the central Pro(2)-Hyp(3)-Gly(4)-Igl(5) tetrapeptide has been replaced by constrained N-1-substituted-1,3,8-triazaspiro¿4. 5decan-4-one ring system were synthesized. Among these analogues, compound JMV1640 (1) was found to have an affinity of 24.10 +/- 9.48 nM for the human cloned B(1) receptor. It antagonized the ¿des-Arg(10)-kallidin-induced contraction of the human umbilical vein (pA(2) = 6.1 +/- 0.1). Compound 1 was devoid of agonist activity at the kinin B(1) receptor. Moreover, it did not bind to the human cloned B(2) receptor. Therefore, JMV1640 constitutes a lead compound for the rational search of nonpeptide B(1) receptor analogues based on the BK sequence.

  12. [N-allyl-Dmt1]-endomorphins are micro-opioid receptor antagonists lacking inverse agonist properties.

    Science.gov (United States)

    Marczak, Ewa D; Jinsmaa, Yunden; Li, Tingyou; Bryant, Sharon D; Tsuda, Yuko; Okada, Yoshio; Lazarus, Lawrence H

    2007-10-01

    [N-allyl-Dmt1]-endomorphin-1 and -2 ([N-allyl-Dmt1]-EM-1 and -2) are new selective micro-opioid receptor antagonists obtained by N-alkylation with an allyl group on the amino terminus of 2',6'-dimethyl-L-tyrosine (Dmt) derivatives. To further characterize properties of these compounds, their intrinsic activities were assessed by functional guanosine 5'-O-(3-[35S]thiotriphosphate) binding assays and forskolin-stimulated cyclic AMP accumulation in cell membranes obtained from vehicle, morphine, and ethanol-treated SK-N-SH cells and brain membranes isolated from naive and morphine-dependent mice; their mode of action was compared with naloxone or naltrexone, which both are standard nonspecific opioid-receptor antagonists. [N-allyl-Dmt1]-EM-1 and -2 were neutral antagonists under all of the experimental conditions examined, in contrast to naloxone and naltrexone, which behave as neutral antagonists only in membranes from vehicle-treated cells and mice but act as inverse agonists in membranes from morphine- and ethanol-treated cells as well as morphine-treated mice. Both endomorphin analogs inhibited the naloxone- and naltrexone-elicited withdrawal syndromes from acute morphine dependence in mice. This suggests their potential therapeutic application in the treatment of drug addiction and alcohol abuse without the adverse effects observed with inverse agonist alkaloid-derived compounds that produce severe withdrawal symptoms.

  13. Structural and thermodynamic bases for the design of pure prolactin receptor antagonists: X-ray structure of Del1-9-G129R-hPRL

    DEFF Research Database (Denmark)

    Jomain, Jean-Baptiste; Tallet, Estelle; Broutin, Isabelle;

    2007-01-01

    Competitive antagonists of the human prolactin (hPRL) receptor are a novel class of molecules of potential therapeutic interest in the context of cancer. We recently developed the pure antagonist Del1-9-G129R-hPRL by deleting the nine N-terminal residues of G129R-hPRL, a first generation partial...... antagonist. We determined the crystallographic structure of Del1-9-G129R-hPRL, which revealed no major change compared with wild type hPRL, indicating that its pure antagonistic properties are intrinsically due to the mutations. To decipher the molecular bases of pure antagonism, we compared the biological...... agonism can be abolished either by further disrupting hormone site 2-receptor contacts by N-terminal deletion, as in Del1-9-G129R-hPRL, or by stabilizing hPRL and constraining its intrinsic flexibility, as in G129V-hPRL. Udgivelsesdato: 2007-Nov-9...

  14. Structural basis for simvastatin competitive antagonism of complement receptor 3

    DEFF Research Database (Denmark)

    Jensen, Maria Risager; Bajic, Goran; Zhang, Xianwei;

    2016-01-01

    The complement system is an important part of the innate immune response to infection, but may also cause severe complications during inflammation. Small molecule antagonists to complement receptor (CR)3 have been widely sought, but a structural basis for their mode of action is not available. We...... report here on the structure of the human CR3 ligand-binding I domain in complex with simvastatin. Simvastatin targets the metal ion-dependent adhesion site of the open, ligand-binding conformation of the CR3 I domain by direct contact with the chelated Mg2+ ion. Simvastatin antagonizes I domain binding...... to the complement fragments iC3b and C3d, but not to intercellular adhesion molecule-1. By virtue of the I domain's wide distribution in binding kinetics to ligands, it was possible to identify ligand binding kinetics as discriminator for simvastatin antagonism. In static cellular experiments, 15-25 μM simvastatin...

  15. Immunoactive effects of cannabinoids: considerations for the therapeutic use of cannabinoid receptor agonists and antagonists.

    Science.gov (United States)

    Greineisen, William E; Turner, Helen

    2010-05-01

    The active constituents of Cannabis sativa have been used for centuries as recreational drugs and medicinal agents. Today, marijuana is the most prevalent drug of abuse in the United States and, conversely, therapeutic use of marijuana constituents are gaining mainstream clinical and political acceptance. Given the documented contributions of endocannabinoid signaling to a range of physiological systems, including cognitive function, and the control of eating behaviors, it is unsurprising that cannabinoid receptor agonists and antagonists are showing significant clinical potential. In addition to the neuroactive effects of cannabinoids, an emerging body of data suggests that both endogenous and exogenous cannabinoids are potently immunoactive. The central premise of this review article is that the immunological effects of cannabinoids should be considered in the context of each prescribing decision. We present evidence that the immunological effects of cannabinoid receptor agonists and antagonists are highly relevant to the spectrum of disorders for which cannabinoid therapeutics are currently offered.

  16. ANALYSIS OF INTERLEUKIN-1 RECEPTOR ANTAGONIST GENE POLYMORPHISM IN CHINESE PATIENTS WITH ALZHEIMER'S DISEASE

    Institute of Scientific and Technical Information of China (English)

    Sheng Bi; De-sheng Wang; Guo-lin Li; Shang-ha Pan

    2004-01-01

    Objective To identify an interaction between the interleukin-1 receptor antagonist gene polymorphism and risk of Alzheimer's disease.Methods The study included 117 healthy controls, 85 patients with Alzheimer's disease in a Northeastern Chinese population of Han nationality. Genotypes were determined by a polymerase chain reaction amplification of the intron 2 fragment,harbouring a variable number of short tandem nucleotide sequences. Amplification products were separated on a 2% agarose gel.Results The allele 2 frequency was 27% in healthy controls, and 21% in patients with Alzheimer's disease. Thus for allele 2 as well as for all other alleles, genotypes, or carriage rates, no significant differences compared with controls.Conclusions No association ofinterleukin-1 receptor antagonist gene polymorphism with Alzheimer's disease was identified in this population. It is also possible that the increased risk and disease modifying effects are caused by linkage disequilibrium with other genomic variants in other nearby genes.

  17. The safety of interleukin-1 receptor antagonist (anakinra in the treatment of rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    L. Riente

    2011-09-01

    Full Text Available The safety profile of interleukin-1 receptor antagonist (anakinra has been studied with randomised, placebo-controlled trials involving 2932 patients affected by rheumatoid arthritis. The most frequently reported adverse events were represented by injection site reactions (71% and headache (13.6%. No statistically significant difference in the incidence of infections was observed among the patients treated with the interleukin-1 receptor antagonist and the patients receiving placebo. In particular, the incidence of serious infections was 1,8% in rheumatoid arthritis patients on anakinra therapy and 0,7% in patients on placebo. The reported serious infections consisted of pneumonia, cellulitis, bone and joint infections, bursitis. No case of opportunistic infections or tubercolosis was observed. The results of clinical studies suggest that anakinra is a new well-tolerated drug for the treatment of patients affected by rheumatoid arthritis.

  18. How microelectrode array-based chick forebrain neuron biosensors respond to glutamate NMDA receptor antagonist AP5 and GABAA receptor antagonist musimol

    Directory of Open Access Journals (Sweden)

    Serena Y. Kuang

    2016-09-01

    Full Text Available We have established a long-term, stable primary chick forebrain neuron (FBN culture on a microelectrode array platform as a biosensor system for neurotoxicant screening and for neuroelectrophysiological studies for multiple purposes. This paper reports some of our results, which characterize the biosensor pharmacologically. Dose-response experiments were conducted using NMDA receptor antagonist AP5 and GABAA receptor agonist musimol (MUS. The chick FBN biosensor (C-FBN-biosensor responds to the two agents in a pattern similar to that of rodent counterparts; the estimated EC50s (the effective concentration that causes 50% inhibition of the maximal effect are 2.3 μM and 0.25 μM, respectively. Intercultural and intracultural reproducibility and long-term reusability of the C-FBN-biosensor are addressed and discussed. A phenomenon of sensitization of the biosensor that accompanies intracultural reproducibility in paired dose-response experiments for the same agent (AP5 or MUS is reported. The potential application of the C-FBN-biosensor as an alternative to rodent biosensors in shared sensing domains (NMDA receptor and GABAA receptor is suggested.

  19. Relaxant effect of the H2-receptor antagonist oxmetidine on guinea-pig and human airways.

    OpenAIRE

    Advenier, C; Gnassounou, J. P.; Scarpignato, C.

    1987-01-01

    The effects of three different H2-receptor antagonists (cimetidine, ranitidine and oxmetidine) were tested on isolated preparations of guinea-pig trachea and human bronchus against contractions induced by acetylcholine, histamine and potassium chloride (KCl). In addition, their influence on calcium concentration-response curves in guinea-pig tracheal spirals was examined in a potassium-rich solution (30 mM). Finally, their effects were studied in vivo against acetylcholine and histamine-induc...

  20. A novel series of glucagon receptor antagonists with reduced molecular weight and lipophilicity.

    Science.gov (United States)

    Filipski, Kevin J; Bian, Jianwei; Ebner, David C; Lee, Esther C Y; Li, Jian-Cheng; Sammons, Matthew F; Wright, Stephen W; Stevens, Benjamin D; Didiuk, Mary T; Tu, Meihua; Perreault, Christian; Brown, Janice; Atkinson, Karen; Tan, Beijing; Salatto, Christopher T; Litchfield, John; Pfefferkorn, Jeffrey A; Guzman-Perez, Angel

    2012-01-01

    A novel series of glucagon receptor antagonists has been discovered. These pyrazole ethers and aminopyrazoles have lower molecular weight and increased polarity such that the molecules fall into better drug-like property space. This work has culminated in compounds 44 and 50 that were shown to have good pharmacokinetic attributes in dog, in contrast to rats, in which clearance was high; and compound 49, which demonstrated a dose-dependent reduction in glucose excursion in a rat glucagon challenge experiment.

  1. An Autoinflammatory Disease with Deficiency of the Interleukin-1–Receptor Antagonist

    Science.gov (United States)

    Aksentijevich, Ivona; Masters, Seth L.; Ferguson, Polly J.; Dancey, Paul; Frenkel, Joost; van Royen-Kerkhoff, Annet; Laxer, Ron; Tedgård, Ulf; Cowen, Edward W.; Pham, Tuyet-Hang; Booty, Matthew; Estes, Jacob D.; Sandler, Netanya G.; Plass, Nicole; Stone, Deborah L.; Turner, Maria L.; Hill, Suvimol; Butman, John A.; Schneider, Rayfel; Babyn, Paul; El-Shanti, Hatem I.; Pope, Elena; Barron, Karyl; Bing, Xinyu; Laurence, Arian; Lee, Chyi-Chia R.; Chapelle, Dawn; Clarke, Gillian I.; Ohson, Kamal; Nicholson, Marc; Gadina, Massimo; Yang, Barbara; Korman, Benjamin D.; Gregersen, Peter K.; van Hagen, P. Martin; Hak, A. Elisabeth; Huizing, Marjan; Rahman, Proton; Douek, Daniel C.; Remmers, Elaine F.; Kastner, Daniel L.; Goldbach-Mansky, Raphaela

    2010-01-01

    Background Autoinflammatory diseases manifest inflammation without evidence of infection, high-titer autoantibodies, or autoreactive T cells. We report a disorder caused by mutations of IL1RN, which encodes the interleukin-1–receptor antagonist, with prominent involvement of skin and bone. Methods We studied nine children from six families who had neonatal onset of sterile multifocal osteomyelitis, periostitis, and pustulosis. Response to empirical treatment with the recombinant interleukin-1–receptor antagonist anakinra in the first patient prompted us to test for the presence of mutations and changes in proteins and their function in interleukin-1–pathway genes including IL1RN. Results We identified homozygous mutations of IL1RN in nine affected children, from one family from Newfoundland, Canada, three families from the Netherlands, and one consanguineous family from Lebanon. A nonconsanguineous patient from Puerto Rico was homozygous for a genomic deletion that includes IL1RN and five other interleukin-1–family members. At least three of the mutations are founder mutations; heterozygous carriers were asymptomatic, with no cytokine abnormalities in vitro. The IL1RN mutations resulted in a truncated protein that is not secreted, thereby rendering cells hyperresponsive to interleukin-1β stimulation. Patients treated with anakinra responded rapidly. Conclusions We propose the term deficiency of the interleukin-1–receptor antagonist, or DIRA, to denote this autosomal recessive autoinflammatory disease caused by mutations affecting IL1RN. The absence of interleukin-1–receptor antagonist allows unopposed action of interleukin-1, resulting in life-threatening systemic inflammation with skin and bone involvement. (ClinicalTrials.gov number, NCT00059748.) PMID:19494218

  2. Cardiovascular effects of selective agonists and antagonists of histamine H3 receptors in the anaesthetized rat.

    Science.gov (United States)

    Coruzzi, G; Gambarelli, E; Bertaccini, G; Timmerman, H

    1995-06-01

    The cardiovascular responses to a series of selective histamine H3 receptor agonists, (R) alpha-methylhistamine, imetit and immepip and selective antagonists, thioperamide, clobenpropit and clophenpropit, were studied in anaesthetized rats. At 0.003-1 mumol/kg i.v. doses, H3 agonists failed to produce any significant change in the basal blood pressure and heart rate. Larger doses of (R) alpha-methylhistamine increased the blood pressure and heart rate and higher doses of imetit caused vasodepressor responses and reduced heart rate, whereas immepip proved virtually inactive. While (R) alpha-methylhistamine-induced effects were not blocked by histamine H1-, H2- and H3-receptor antagonists, they were however reduced by idazoxan and propranolol, which indicates that the mechanisms involved are adrenergic. The effects induced by imetit are not related to histamine H3 receptors but are mediated by indirect (via 5HT3 receptors) cholinergic mechanisms, since these effects were prevented by 1 mg/kg i.v. atropine and by 0.1 mg/kg i.v. ondansetron. Similarly, the H3 antagonists per se failed to change basal cardiovascular function up to 10 mumol/kg i.v. and only at 30 mumol/kg i.v. were marked decreases observed in the blood pressure and heart rate with a significant reduction in the effects of noradrenaline. These data indicate that in anaesthetized rats, histamine H3 receptor activation or blockade has no effect on basal cardiovascular function. The effects recorded after the administration of large doses of (R) alpha-methylhistamine and imetit are clearly unrelated to histamine H3 receptors and should be taken into account when using these compounds as H3 ligands for "in vivo" experiments.

  3. Efficient photoaffinity labeling of the rat V1a vasopressin receptor using a linear azidopeptidic antagonist.

    Science.gov (United States)

    Carnazzi, E; Aumelas, A; Phalipou, S; Mouillac, B; Guillon, G; Barberis, C; Seyer, R

    1997-08-01

    We have synthesized and fully characterized by fast-atom-bombardment-mass, NMR and ultraviolet spectroscopies the vasopressin antagonist 3-azidophenylpropionyl-D-Tyr(Me)-Phe-Gln-Asn-Arg-Pro-Arg-Tyr(3I )-NH2. Easily radioiodinatable just before use, it has a high affinity for the natural rat liver V1a receptor [dissociation constant (Kd) = 54 +/- 20 pM; Carnazzi, E., Aumelas, A., Barberis, C., Guillon, G. & Seyer, R. (1994) J. Med. Chem. 37, 1841-1849] and for both the rat vasopressin V1a receptor expressed in Spodoptera frugiperda 9 cells (Sf9 cells, Kd = 688 +/- 35 pM) and in COS-7 cells (Kd = 320 +/- 20 pM). This probe labels specifically the V1a receptors in an ultraviolet-dependent manner, and binds covalently to about 12% of the receptors with high stability over several days, even in dissociation or solubilization conditions. SDS/PAGE studies and autoradiographic analyses of the photolabeled receptors reveal a single band (49.5 kDa) and two bands (63 kDa and 93.6 kDa) for receptor-probe associations obtained in Sf9 and COS-7 cells respectively. These molecular masses are consistent with non-glycosylated and highly glycosylated forms of the receptor, according to each expression system. In rat liver membranes, we have identified apparent molecular masses of about 32, 45 and more than 67 kDa. We finally demonstrated a proteolysis of the receptor that appeared to be Zn2+ and leupeptin sensitive. The high potency of this ligand is promising for the monitoring of the purification of the V1a receptor and for mapping its antagonist-binding site.

  4. Extended N-Arylsulfonylindoles as 5-HT₆ Receptor Antagonists: Design, Synthesis & Biological Evaluation.

    Science.gov (United States)

    Vera, Gonzalo; Lagos, Carlos F; Almendras, Sebastián; Hebel, Dan; Flores, Francisco; Valle-Corvalán, Gissella; Pessoa-Mahana, C David; Mella-Raipán, Jaime; Montecinos, Rodrigo; Recabarren-Gajardo, Gonzalo

    2016-08-16

    Based on a known pharmacophore model for 5-HT₆ receptor antagonists, a series of novel extended derivatives of the N-arylsulfonyindole scaffold were designed and identified as a new class of 5-HT₆ receptor modulators. Eight of the compounds exhibited moderate to high binding affinities and displayed antagonist profile in 5-HT₆ receptor functional assays. Compounds 2-(4-(2-methoxyphenyl)piperazin-1-yl)-1-(1-tosyl-1H-indol-3-yl)ethanol (4b), 1-(1-(4-iodophenylsulfonyl)-1H-indol-3-yl)-2-(4-(2-methoxyphenyl)piperazin-1-yl)ethanol (4g) and 2-(4-(2-methoxyphenyl)piperazin-1-yl)-1-(1-(naphthalen-1-ylsulfonyl)-1H-indol-3-yl)ethanol (4j) showed the best binding affinity (4b pKi = 7.87; 4g pKi = 7.73; 4j pKi = 7.83). Additionally, compound 4j was identified as a highly potent antagonist (IC50 = 32 nM) in calcium mobilisation functional assay.

  5. Extended N-Arylsulfonylindoles as 5-HT6 Receptor Antagonists: Design, Synthesis & Biological Evaluation

    Directory of Open Access Journals (Sweden)

    Gonzalo Vera

    2016-08-01

    Full Text Available Based on a known pharmacophore model for 5-HT6 receptor antagonists, a series of novel extended derivatives of the N-arylsulfonyindole scaffold were designed and identified as a new class of 5-HT6 receptor modulators. Eight of the compounds exhibited moderate to high binding affinities and displayed antagonist profile in 5-HT6 receptor functional assays. Compounds 2-(4-(2-methoxyphenylpiperazin-1-yl-1-(1-tosyl-1H-indol-3-ylethanol (4b, 1-(1-(4-iodophenylsulfonyl-1H-indol-3-yl-2-(4-(2-methoxyphenylpiperazin-1-ylethanol (4g and 2-(4-(2-methoxyphenylpiperazin-1-yl-1-(1-(naphthalen-1-ylsulfonyl-1H-indol-3-ylethanol (4j showed the best binding affinity (4b pKi = 7.87; 4g pKi = 7.73; 4j pKi = 7.83. Additionally, compound 4j was identified as a highly potent antagonist (IC50 = 32 nM in calcium mobilisation functional assay.

  6. Attenuation of morphine antinociceptive tolerance by cannabinoid CB1 and CB2 receptor antagonists.

    Science.gov (United States)

    Altun, Ahmet; Yildirim, Kemal; Ozdemir, Ercan; Bagcivan, Ihsan; Gursoy, Sinan; Durmus, Nedim

    2015-09-01

    Cannabinoid CB1 and CB2 receptor antagonists may be useful for their potential to increase or prolong opioid analgesia while attenuating the development of opioid tolerance. The aim of this study was to investigate the effects of AM251 (a selective CB1 antagonist) and JTE907 (a selective CB2 antagonist) on morphine analgesia and tolerance in rats. Adult male Wistar albino rats weighing 205-225 g were used in these experiments. To constitute morphine tolerance, we used a 3 day cumulative dosing regimen. After the last dose of morphine was injected on day 4, morphine tolerance was evaluated by analgesia tests. The analgesic effects of morphine (5 mg/kg), ACEA (a CB1 receptor agonist, 5 mg/kg), JWH-015 (a CB2 receptor agonist, 5 mg/kg), AM251 (1 mg/kg) and JTE907 (5 mg/kg) were considered at 30-min intervals (0, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests. Our findings indicate that ACEA and JWH907 significantly increased morphine analgesia and morphine antinociceptive tolerance in the analgesia tests. In contrast, the data suggested that AM251 and JTE907 significantly attenuated the expression of morphine tolerance. In conclusion, we observed that co-injection of AM251 and JTE907 with morphine attenuated expression of tolerance to morphine analgesic effects and decreased the morphine analgesia.

  7. Naphthalene/quinoline amides and sulfonylureas as potent and selective antagonists of the EP4 receptor.

    Science.gov (United States)

    Burch, Jason D; Farand, Julie; Colucci, John; Sturino, Claudio; Ducharme, Yves; Friesen, Richard W; Lévesque, Jean-François; Gagné, Sébastien; Wrona, Mark; Therien, Alex G; Mathieu, Marie-Claude; Denis, Danielle; Vigneault, Erika; Xu, Daigen; Clark, Patsy; Rowland, Steve; Han, Yongxin

    2011-02-01

    Two new series of EP(4) antagonists based on naphthalene/quinoline scaffolds have been identified as part of our on-going efforts to develop treatments for inflammatory pain. One series contains an acidic sulfonylurea pharmacophore, whereas the other is a neutral amide. Both series show subnanomolar intrinsic binding potency towards the EP(4) receptor, and excellent selectivity towards other prostanoid receptors. While the amide series generally displays poor pharmacokinetic parameters, the sulfonylureas exhibit greatly improved profile. MF-592, the optimal compound from the sulfonylurea series, has a desirable overall preclinical profile that suggests it is suitable for further development.

  8. New insights into the stereochemical requirements of the bradykinin B2 receptor antagonists binding

    Science.gov (United States)

    Lupala, Cecylia S.; Gomez-Gutierrez, Patricia; Perez, Juan J.

    2016-01-01

    Bradykinin (BK) is a member of the kinin family, released in response to inflammation, trauma, burns, shock, allergy and some cardiovascular diseases, provoking vasodilatation and increased vascular permeability among other effects. Their actions are mediated through at least two G-protein coupled receptors, B1 a receptor up-regulated during inflammation episodes or tissue trauma and B2 that is constitutively expressed in a variety of cell types. The goal of the present work is to carry out a structure-activity study of BK B2 antagonism, taking into account the stereochemical features of diverse non-peptide antagonists and the way these features translate into ligand anchoring points to complementary regions of the receptor, through the analysis of the respective ligand-receptor complex. For this purpose an atomistic model of the BK B2 receptor was built by homology modeling and subsequently refined embedded in a lipid bilayer by means of a 600 ns molecular dynamics trajectory. The average structure from the last hundred nanoseconds of the molecular dynamics trajectory was energy minimized and used as model of the receptor for docking studies. For this purpose, a set of compounds with antagonistic profile, covering maximal diversity were selected from the literature. Specifically, the set of compounds include Fasitibant, FR173657, Anatibant, WIN64338, Bradyzide, CHEMBL442294, and JSM10292. Molecules were docked into the BK B2 receptor model and the corresponding complexes analyzed to understand ligand-receptor interactions. The outcome of this study is summarized in a 3D pharmacophore that explains the observed structure-activity results and provides insight into the design of novel molecules with antagonistic profile. To prove the validity of the pharmacophore hypothesized a virtual screening process was also carried out. The pharmacophore was used as query to identify new hits using diverse databases of molecules. The results of this study revealed a set of new

  9. AMPA receptor competitive antagonism reduces halothane MAC in rats.

    Science.gov (United States)

    McFarlane, C; Warner, D S; Todd, M M; Nordholm, L

    1992-12-01

    Various subtypes of receptors have been identified for glutamate, an excitatory neurotransmitter. Previous studies have shown that antagonism of glutamate at the NMDA receptors reduces minimum alveolar concentration (MAC) for volatile anesthetics. NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline) is a selective antagonist at the glutamatergic AMPA receptor. The purpose of this experiment was to determine whether AMPA receptor antagonism influences halothane MAC in the rat. Sprague-Dawley rats were anesthetized with halothane in 50% O2/balance N2, tracheally intubated and the lungs were mechanically ventilated. Increasing doses of NBQX were intravenously infused in three groups while the control group was infused with vehicle (D5W). Halothane MAC was then determined by the tail-clamp method. Halothane MAC was log-linearly related to plasma NBQX concentrations (MAC = 0.125 (In plasma concentration NBQX) + 1.035, r2 = 0.77). A maximal 58% reduction of halothane MAC was achieved with an NBQX loading dose of 42 mg/kg followed by a continuous infusion rate of 36 mg x kg-1 x h-1 (control = 1.02 +/- 0.07%; NBQX = 0.43 +/- 0.12%; P awake rats were randomly assigned to groups based on the dose of NBQX infused. Pa(CO2) and mean arterial pressure were measured at time 0 and at 5 and 30 min after start of NBQX infusion. The infusion was then stopped. Time until recovery of the righting reflex was recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Examining SLV-323, a novel NK1 receptor antagonist, in a chronic psychosocial stress model for depression

    NARCIS (Netherlands)

    Czeh, B; Pudovkina, O; van der Hart, MGC; Simon, M; Heilbronner, U; Michaelis, T; Watanabe, T; Frahm, J; Fuchs, E

    2005-01-01

    Rationale: Substance P antagonists have been proposed as candidates for a new class of antidepressant compounds. Objectives: We examined the effects of SLV-323, a novel neurokinin 1 receptor (NK1R) antagonist, in the chronic psychosocial stress paradigm of adult male tree shrews. Methods: Animals we

  11. Effects of iodoproxyfan, a potent and selective histamine H3 receptor antagonist, on alpha 2 and 5-HT3 receptors.

    Science.gov (United States)

    Schlicker, E; Pertz, H; Bitschnau, H; Purand, K; Kathmann, M; Elz, S; Schunack, W

    1995-07-01

    We determined the affinity and/or potency of the novel H3 receptor antagonist iodoproxyfan at alpha 2 and 5-HT3 receptors. Iodoproxyfan and rauwolscine (a reference alpha 2 ligand) (i) monophasically displaced 3H-rauwolscine binding to rat brain cortex membranes (pKi 6.79 and 8.59); (ii) facilitated the electrically evoked tritium overflow from superfused mouse brain cortex slices preincubated with 3H-noradrenaline (pEC50 6.46 and 7.91) and (iii) produced rightward shifts of the concentration-response curve (CRC) of (unlabelled) noradrenaline for its inhibitory effect on the evoked overflow (pA2 6.65 and 7.88). In the guinea-pig ileum, iodoproxyfan 6.3 mumol/l failed to evoke a contraction by itself but depressed the maximum of the CRC of 5-hydroxytryptamine (pD'2 5.24). Tropisetron (a reference 5-HT3 antagonist) produced rightward shifts of the CRC of 5-hydroxytryptamine (pA2 7.84). In conclusion, the affinity/potency of iodoproxyfan at H3 receptors (range 8.3-9.7 [1]) exceeds that at alpha 2 receptors by at least 1.5 log units and that at 5-HT3 receptors by at least 3 log units.

  12. Possible Mechanisms for Functional Antagonistic Effect of Ferula assafoetida on Muscarinic Receptors in Tracheal Smooth Muscle

    Science.gov (United States)

    Kiyanmehr, Majid; Boskabady, Mohammad Hossein; Khazdair, Mohammad Reza; Hashemzehi, Milad

    2016-01-01

    Background The contribution of histamine (H1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of Ferula assa-foetida. (F. asafoetida) was examined in the present study. Methods We evaluated the effect of three concentrations of F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H1) (group 1), and only β-adrenergic (group 2) receptors antagonists. Results EC50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001, P = 0.0477, and P = 0.0008 in group 1 and P < 0.0001, P = 0.0438, and P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and P < 0.0001 for other extract concentrations in both groups). Conclusion Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of F. asafoetida in tracheal smooth muscle PMID:27540324

  13. The combination of glutamate receptor antagonist MK-801 with tamoxifen and its active metabolites potentiates their antiproliferative activity in mouse melanoma K1735-M2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Mariana P.C. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal); Nunes-Correia, Isabel [Center for Neuroscience and Cell Biology, Flow Cytometry Unit, University of Coimbra, 3000-354 Coimbra (Portugal); Santos, Armanda E., E-mail: aesantos@ci.uc.pt [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal); Custódio, José B.A. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal)

    2014-02-15

    Recent reports suggest that N-methyl-D-aspartate receptor (NMDAR) blockade by MK-801 decreases tumor growth. Thus, we investigated whether other ionotropic glutamate receptor (iGluR) antagonists were also able to modulate the proliferation of melanoma cells. On the other hand, the antiestrogen tamoxifen (TAM) decreases the proliferation of melanoma cells, and is included in combined therapies for melanoma. As the efficacy of TAM is limited by its metabolism, we investigated the effects of the NMDAR antagonist MK-801 in combination with TAM and its active metabolites, 4-hydroxytamoxifen (OHTAM) and endoxifen (EDX). The NMDAR blockers MK-801 and memantine decreased mouse melanoma K1735-M2 cell proliferation. In contrast, the NMDAR competitive antagonist APV and the AMPA and kainate receptor antagonist NBQX did not affect cell proliferation, suggesting that among the iGluR antagonists only the NMDAR channel blockers inhibit melanoma cell proliferation. The combination of antiestrogens with MK-801 potentiated their individual effects on cell biomass due to diminished cell proliferation, since it decreased the cell number and DNA synthesis without increasing cell death. Importantly, TAM metabolites combined with MK-801 promoted cell cycle arrest in G1. Therefore, the data obtained suggest that the activity of MK-801 and antiestrogens in K1735-M2 cells is greatly enhanced when used in combination. - Highlights: • MK-801 and memantine decrease melanoma cell proliferation. • The combination of MK-801 with antiestrogens inhibits melanoma cell proliferation. • These combinations greatly enhance the effects of the compounds individually. • MK-801 combined with tamoxifen active metabolites induces cell cycle arrest in G1. • The combination of MK-801 and antiestrogens is an innovative strategy for melanoma.

  14. Different antagonist binding properties of rat pancreatic and cardiac muscarinic receptors

    Energy Technology Data Exchange (ETDEWEB)

    Waelbroeck, M.; Camus, J.; Winand, J.; Christophe, J.

    1987-11-09

    The antagonist binding properties of rat pancreatic and cardiac muscarinic receptors were compared. In both tissues pirenzepine (PZ) had a low affinity for muscarinic receptors labelled by (/sup 3/H)N-methylscopolamine ((/sup 3/)NMS) (K/sub D/ values of 140 and 280nM, respectively, in pancreatic and cardiac homogenates). The binding properties of pancreatic and cardiac receptors were, however, markedly different. This was indicated by different affinities for dicyclomine, (11-(/(2-((diethylamino)-methyl)-1-piperidinyl/acetyl)-5, 11-dihydro-6H-pyrido(2,3-b)(1,4) benzodiazepin-6-on)(AFDX-116), 4-diphenylacetoxy-N-methyl-piperidine methobromide (4-DAMP) and hexahydrosiladifenidol (HHSiD). Pancreatic and cardiac muscarinic receptros also showed different (/sup 3/H)NMS association and dissociation rates. These results support the concept of M2 receptor subtypes have different binding kinetic properties. 20 references, 3 figures, 1 table.

  15. Oxime Ethers of (E)-11-Isonitrosostrychnine as Highly Potent Glycine Receptor Antagonists

    DEFF Research Database (Denmark)

    Mohsen, Amal M Y; Mandour, Yasmine M; Sarukhanyan, Edita

    2016-01-01

    A series of (E)-11-isonitrosostrychnine oxime ethers, 2-aminostrychnine, (strychnine-2-yl)propionamide, 18-oxostrychnine, and N-propylstrychnine bromide were synthesized and evaluated pharmacologically at human α1 and α1β glycine receptors in a functional fluorescence-based and a whole-cell patch......-clamp assay and in [(3)H]strychnine binding studies. 2-Aminostrychnine and the methyl, allyl, and propargyl oxime ethers were the most potent α1 and α1β antagonists in the series, displaying IC50 values similar to those of strychnine at the two receptors. Docking experiments to the strychnine binding site...... of the crystal structure of the α3 glycine receptor indicated the same orientation of the strychnine core for all analogues. For the most potent oxime ethers, the ether substituent was accommodated in a lipophilic receptor binding pocket. The findings identify the oxime hydroxy group as a suitable attachment...

  16. Early Use of the NMDA Receptor Antagonist Ketamine in Refractory and Superrefractory Status Epilepticus

    Directory of Open Access Journals (Sweden)

    F. A. Zeiler

    2015-01-01

    Full Text Available Refractory status epilepticus (RSE and superrefractory status epilepticus (SRSE pose a difficult clinical challenge. Multiple cerebral receptor and transporter changes occur with prolonged status epilepticus leading to pharmacoresistance patterns unfavorable for conventional antiepileptics. In particular, n-methyl-d-aspartate (NMDA receptor upregulation leads to glutamate mediated excitotoxicity. Targeting these NMDA receptors may provide a novel approach to otherwise refractory seizures. Ketamine has been utilized in RSE. Recent systematic review indicates 56.5% and 63.5% cessation in seizures in adults and pediatrics, respectively. No complications were described. We should consider earlier implementation of ketamine or other NMDA receptor antagonists, for RSE. Prospective study of early implementation of ketamine should shed light on the role of such medications in RSE.

  17. Similarities and Distinctions in Actions of Surface-Directed and Classic Androgen Receptor Antagonists.

    Directory of Open Access Journals (Sweden)

    Ji Ho Suh

    Full Text Available The androgen receptor (AR surface-directed antagonist MJC13 inhibits AR function and proliferation of prostate cancer (PC cells. These effects are related to arrest of an AR/chaperone complex in the cytoplasm. Here, we compared MJC13 and classic AR antagonists such as flutamide and bicalutamide. Microarray analysis and confirmatory qRT-PCR reveals that MJC13 and flutamide inhibit dihydrotestosterone (DHT-dependent genes in LNCaP PC cells. Both compounds are equally effective on a genome wide basis and as effective as second generation AR antagonists (MDV3100, ARN-509 at selected genes. MJC13 inhibits AR binding to the prostate specific antigen (PSA promoter more strongly than flutamide, consistent with different mechanisms of action. Examination of efficacy of MJC13 in conditions that reflect aspects castrate resistant prostate cancer (CRPC reveals that it inhibits flutamide activation of an AR mutant (ART877A that emerges during flutamide withdrawal syndrome, but displays greatly restricted gene-specific activity in 22Rv1 cells that express a constitutively active truncated AR and is inactive against glucocorticoid receptor (GR, which can co-opt androgen-dependent signaling networks in CRPC. Importantly, MJC13 inhibits AR interactions with SRC2 and β-catenin in the nucleus and, unlike flutamide, strongly inhibits amplification of AR activity obtained with transfected SRC2 and β-catenin. MJC13 also inhibits DHT and β-catenin-enhanced cell division in LNCaP cells. Thus, a surface-directed antagonist can block AR activity in some conditions in which a classic antagonist fails and may display utility in particular forms of CRPC.

  18. Similarities and Distinctions in Actions of Surface-Directed and Classic Androgen Receptor Antagonists.

    Science.gov (United States)

    Suh, Ji Ho; Chattopadhyay, Arundhati; Sieglaff, Douglas H; Storer Samaniego, Cheryl; Cox, Marc B; Webb, Paul

    2015-01-01

    The androgen receptor (AR) surface-directed antagonist MJC13 inhibits AR function and proliferation of prostate cancer (PC) cells. These effects are related to arrest of an AR/chaperone complex in the cytoplasm. Here, we compared MJC13 and classic AR antagonists such as flutamide and bicalutamide. Microarray analysis and confirmatory qRT-PCR reveals that MJC13 and flutamide inhibit dihydrotestosterone (DHT)-dependent genes in LNCaP PC cells. Both compounds are equally effective on a genome wide basis and as effective as second generation AR antagonists (MDV3100, ARN-509) at selected genes. MJC13 inhibits AR binding to the prostate specific antigen (PSA) promoter more strongly than flutamide, consistent with different mechanisms of action. Examination of efficacy of MJC13 in conditions that reflect aspects castrate resistant prostate cancer (CRPC) reveals that it inhibits flutamide activation of an AR mutant (ART877A) that emerges during flutamide withdrawal syndrome, but displays greatly restricted gene-specific activity in 22Rv1 cells that express a constitutively active truncated AR and is inactive against glucocorticoid receptor (GR), which can co-opt androgen-dependent signaling networks in CRPC. Importantly, MJC13 inhibits AR interactions with SRC2 and β-catenin in the nucleus and, unlike flutamide, strongly inhibits amplification of AR activity obtained with transfected SRC2 and β-catenin. MJC13 also inhibits DHT and β-catenin-enhanced cell division in LNCaP cells. Thus, a surface-directed antagonist can block AR activity in some conditions in which a classic antagonist fails and may display utility in particular forms of CRPC.

  19. Dopamine receptors antagonistically regulate behavioral choice between conflicting alternatives in C. elegans.

    Directory of Open Access Journals (Sweden)

    Daoyong Wang

    Full Text Available Caenorhabditis elegans is a useful model to study the neuronal or molecular basis for behavioral choice, a specific form of decision-making. Although it has been implied that both D1-like and D2-like dopamine receptors may contribute to the control of decision-making in mammals, the genetic interactions between D1-like and D2-like dopamine receptors in regulating decision-making are still largely unclear. In the present study, we investigated the molecular control of behavioral choice between conflicting alternatives (diacetyl and Cu2+ by D1-like and D2-like dopamine receptors and their possible genetic interactions with C. elegans as the assay system. In the behavioral choice assay system, mutation of dop-1 gene encoding D1-like dopamine receptor resulted in the enhanced tendency to cross the Cu2+ barrier compared with wild-type. In contrast, mutations of dop-2 or dop-3 gene encoding D2-like dopamine receptor caused the weak tendency to cross the Cu2+ barrier compared with wild-type. During the control of behavioral choice, DOP-3 antagonistically regulated the function of DOP-1. The behavioral choice phenotype of dop-2; dop-1dop-3 triple mutant further confirmed the possible antagonistic function of D2-like dopamine receptor on D1-like dopamine receptor in regulating behavioral choice. The genetic assays further demonstrate that DOP-3 might act through Gαo signaling pathway encoded by GOA-1 and EGL-10, and DOP-1 might act through Gαq signaling pathway encoded by EGL-30 and EAT-16 to regulate the behavioral choice. DOP-1 might function in cholinergic neurons to regulate the behavioral choice, whereas DOP-3 might function in GABAergic neurons, RIC, and SIA neurons to regulate the behavioral choice. In this study, we provide the genetic evidence to indicate the antagonistic relationship between D1-like dopamine receptor and D2-like dopamine receptor in regulating the decision-making of animals. Our data will be useful for understanding the

  20. IL-1 receptor antagonist improves morphine and buprenorphine efficacy in a rat neuropathic pain model.

    Science.gov (United States)

    Pilat, Dominika; Rojewska, Ewelina; Jurga, Agnieszka M; Piotrowska, Anna; Makuch, Wioletta; Przewlocka, Barbara; Mika, Joanna

    2015-10-05

    An interesting research and therapeutic problem is the reduced beneficial efficacy of opioids in the treatment of neuropathic pain. The present study sought to investigate the potential role of IL-1 family members in this phenomenon. We studied the time course of changes in IL-1alpha, IL-1beta, IL-1 receptor type I and IL-1 receptor antagonist mRNA and protein levels experienced by rats after chronic constriction injury (CCI) of the sciatic nerve using qRT-PCR and Western blot analysis. In CCI-exposed rats, spinal levels of IL-1alpha mRNA were slightly downregulated on the 7th day, and protein levels were not changed on the 7th and 14th days. Levels of IL-1 receptor antagonist and IL-1 receptor type I were slightly upregulated in the ipsilateral part of the spinal cord on the 7th and 14th days; however, protein levels were not changed at those time points. Interestingly, we observed that IL-1beta mRNA and protein levels were strongly elevated in the ipsilateral part of the dorsal spinal cord on the 7th and 14th days following CCI. Moreover, in rats exposed to a single intrathecal administration of an IL-1 receptor antagonist (100 ng i.t.) on the 7th and 14th day following CCI, symptoms of neuropathic pain were attenuated, and the analgesic effects of morphine (2.5 µg i.t.) and buprenorphine (2.5 µg i.t.) were enhanced. In summary, restoration of the analgesic activity of morphine and buprenorphine by blockade of IL-1 signaling suggests that increased IL-1beta responses may account for the decreased analgesic efficacy of opioids observed in the treatment of neuropathy.

  1. Eplerenone: a selective aldosterone receptor antagonist for hypertension and heart failure.

    Science.gov (United States)

    Moore, Tera D; Nawarskas, James J; Anderson, Joe R

    2003-01-01

    Aldosterone has been implicated for many years as an important substance in the pathogenesis of heart disease. Elevated aldosterone concentrations have been documented in patients with hypertension and heart failure, leading to the use of aldosterone antagonists for the treatment of these conditions. Spironolactone has been used for nearly 2 decades for the treatment of hypertension, and more recently, has become a standard agent for the treatment of systolic heart failure. Spironolactone, however, is a nonselective antagonist of the aldosterone receptor, binding also to other steroid receptors and causing a significant percentage of patients to have sex hormone-related adverse effects such as gynecomastia. Eplerenone is the first of a new class of drugs known as selective aldosterone receptor antagonists, which selectively block the aldosterone receptor with minimal effect at other steroid receptors, thereby minimizing many of the hormonal side effects seen with spironolactone. Eplerenone has been shown to be beneficial both as monotherapy and combination therapy for lowering elevated blood pressure in patients with hypertension. The antihypertensive efficacy of eplerenone is roughly similar to that of other antihypertensive agents, although in 1 study black patients responded better with eplerenone than losartan. In addition, eplerenone has demonstrated some renoprotective effects in diabetic patients with hypertension. Recently, eplerenone was shown to significantly reduce mortality and cardiovascular morbidity in post-myocardial infarction patients with systolic heart failure currently taking standard heart failure medications. Eplerenone is generally well tolerated, although hyperkalemia with this agent is of some concern. Eplerenone is metabolized by CYP3A4 and administration with potent inhibitors of this enzyme is contraindicated because of the risk of hyperkalemia. In summary, eplerenone has proven to be beneficial in treating hypertension and post

  2. Effects of dopamine D1 and D2 receptor antagonists on laryngeal neurophysiology in the rat.

    Science.gov (United States)

    Feng, Xin; Henriquez, Victor M; Walters, Judith R; Ludlow, Christy L

    2009-08-01

    Hypophonia is an early symptom in Parkinson's disease (PD) that involves an increase in laryngeal muscle activity, interfering with voice production. Our aim was to use an animal model to better understand the role of different dopamine receptor subtypes in the control of laryngeal neurophysiology. First, we evaluated the combined effects of SCH23390-a D(1) receptor antagonist with a D(2) receptor antagonist (eticlopride) on laryngeal neurophysiology, and then tested the separate effects of selective receptor antagonists. Thyroarytenoid (TA) and gastrocnemius (GN) muscle activity was measured at rest and while stimulating the internal branch of superior laryngeal nerve to elicit the laryngeal adductor response (LAR) in alpha-chloralose-anesthetized rats. Paired stimuli at different interstimulus intervals between 250 and 5,000 ms measured central conditioning of the LAR. Changes in resting muscle activity, response latency, amplitude, and LAR conditioning after each drug were compared with the saline control. SCH23390 alone increased the resting TA muscle activity (P < 0.05). With the combined SCH23390 + eticlopride or SCH23390 alone, response latency decreased (P < 0.01), amplitude increased (P < 0.01), and the test LAR was reduced at 2,000-ms ISI (P < 0.01). No LAR changes occurred when eticlopride was administered alone at a low dose and only a tendency to suppress responses was found at a high dose. No changes in GN muscle activity occurred in any of the groups. The results suggest that a loss of stimulation of D(1) receptors plays a significant role in laryngeal pathophysiology in PD.

  3. Novel class of medications, orexin receptor antagonists, in the treatment of insomnia - critical appraisal of suvorexant.

    Science.gov (United States)

    Norman, Jessica L; Anderson, Sarah L

    2016-01-01

    Insomnia, a highly prevalent disorder, can be detrimental to patients' overall health and worsen existing comorbidities. Patients may have acute episodes of insomnia related to a traumatic event, but more commonly insomnia occurs chronically. While proper sleep hygiene and behavioral therapy play important roles in the nonpharmacologic management of short-term and chronic insomnia, medications may also be required. Historically, insomnia has been treated with agents such as benzodiazepines, nonbenzodiazepine receptor agonists, and melatonin agonists. Dual orexin receptor antagonists represent a new class of medications for the treatment of insomnia, which block the binding of wakefulness-promoting neuropeptides orexin A and orexin B to their respective receptor sites. Suvorexant (Belsomra) is the first dual orexin receptor antagonist to be approved in the US and Japan and has demonstrated efficacy in decreasing time to sleep onset and increasing total sleep time. Its unique mechanism of action, data to support efficacy and safety over 12 months of use, and relative lack of withdrawal effects when discontinued may represent an alternative for patients with chronic insomnia who cannot tolerate or do not receive benefit from more traditional sleep agents. Suvorexant is effective and well tolerated, but precautions exist for certain patient populations, including females, obese patients, and those with respiratory disease. Suvorexant has only been studied vs placebo, and hence it is unknown how it directly compares with other medications approved by the US Food and Drug Administration for insomnia. Suvorexant is not likely to replace benzodiazepines or nonbenzodiazepine receptor antagonists as a first-line sleep agent but does represent a novel option for the treatment of patients with chronic insomnia.

  4. CP-465,022, a selective noncompetitive AMPA receptor antagonist, blocks AMPA receptors but is not neuroprotective in vivo.

    Science.gov (United States)

    Menniti, Frank S; Buchan, Alistair M; Chenard, Bertrand L; Critchett, Donald J; Ganong, Alan H; Guanowsky, Victor; Seymour, Patricia A; Welch, Willard M

    2003-01-01

    Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor inhibition has been hypothesized to provide neuroprotective efficacy after cerebral ischemia on the basis of the activity in experimental ischemia models of a variety of compounds with varying selectivity for AMPA over other glutamate receptor subtypes. CP-465,022 is a new, potent, and selective noncompetitive AMPA receptor antagonist. The present study investigated the ability of this compound to reduce neuronal loss after experimental cerebral ischemia to probe the neuroprotective potential of AMPA receptor inhibition. To demonstrate that CP-465,022 gains access to the brain, the effects of systemic administration of CP-465,022 were investigated on AMPA receptor-mediated electrophysiological responses in hippocampus and on chemically induced seizures in rats. The compound was then investigated for neuroprotective efficacy in rat global and focal ischemia models at doses demonstrated to be maximally effective in the electrophysiology and seizure models. CP-465,022 potently and efficaciously inhibited AMPA receptor-mediated hippocampal synaptic transmission and the induction of seizures. However, at comparable doses, CP-465,022 failed to prevent CA1 neuron loss after brief global ischemia or to reduce infarct volume after temporary middle cerebral artery occlusion. Given the high selectivity of CP-465,022 for AMPA over kainate and N-methyl-D-aspartate subtypes of glutamate receptors, the lack of neuroprotective efficacy of the compound calls into question the neuroprotective efficacy of AMPA receptor inhibition after ischemia.

  5. Inverse antagonist activities of parabens on human oestrogen-related receptor γ (ERRγ): in vitro and in silico studies.

    Science.gov (United States)

    Zhang, Zhaobin; Sun, Libei; Hu, Ying; Jiao, Jian; Hu, Jianying

    2013-07-01

    Parabens are p-hydroxybenzoic acid esters that have been used extensively as preservatives in foods, cosmetics, drugs and toiletries. These intact esters are commonly detected in human breast cancer tissues and other human samples, thus arousing concern about the involvement of parabens in human breast cancer. In this study, an in vitro nuclear receptor coactivator recruiting assay was developed and used to evaluate the binding activities of parabens, salicylates and benzoates via antagonist competitive binding on the human oestrogen-related receptor γ (ERRγ), which is known as both a diagnostic biomarker and a treatment target of breast cancer. The results showed that all of the test parabens (methyl-, ethyl-, propyl-, butyl- and benzylparaben) possessed clear inverse antagonist activities on ERRγ, with a lowest observed effect level (LOEL) of 10(-7)M and the 50% relative effective concentrations (REC50) varying from 3.09×10(-7) to 5.88×10(-7)M, whereas the salicylates possessed much lower activities and the benzoates showed no obvious activity. In silico molecular docking analyses showed that parabens fitted well into the active site of ERRγ, with hydrogen bonds forming between the p-hydroxyl group of parabens and the Glu275/Arg316 of ERRγ. As the paraben levels reported in breast cancer tissues are commonly higher than the LOELs observed in this study, parabens may play some role via ERRγ in the carcinogenesis of human breast cancer. In addition, parabens may have significant effects on breast cancer patients who are taking tamoxifen, as ERRγ is regarded as a treatment target for tamoxifen. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Studies on the Antihypertensive Mechanism of adrenergic Receptor Antagonist Propranolol : Special Reference to the Role of Vasodilatory Prostaglandins

    OpenAIRE

    西宮, 孝敏; Perry V., Halushka

    1988-01-01

    β-adrenergic receptor antagonists are widely used to treat the patients with hypertension. The mechanism of the antihypertensive effect of these drugs was thought to be associated with 1) negative cardiac inotropic and chronotropic action, 2) suppression of renin secretion, and 3) effects on the central nervous system. However, the precise mechanism is still unknown. Long term therapy with β-adrenergic receptor antagonists is also associated with a reduction in the peripheral vascular resista...

  7. Behavioural interactions between 5-hydroxytryptophan, neuroleptic agents and 5-HT receptor antagonists in modifying rodent responding to aversive situations.

    OpenAIRE

    1995-01-01

    1. The ability of 5-hydroxytryptophan, 5-HT2 receptor antagonists and typical and atypical neuroleptic agents to modify behavioural responding to aversive situations was investigated in the mouse light/dark test and rat social interaction. 2. The administration of 5-hydroxytryptophan inhibited rat social interaction and the exploratory behaviour of mice in the light/dark test. 3. The 5-HT2 receptor antagonists, ketanserin, ritanserin, MDL11939, methysergide and RP62203, the neuroleptic agents...

  8. A Pharmacokinetic/Pharmacodynamic Study of the Glucocorticoid Receptor Antagonist Mifepristone Combined with Enzalutamide in Castrate Resistant Prostate Cancer

    Science.gov (United States)

    2015-12-01

    multifactorial, and likely due to disease, as well as the two study drugs enzalutamide and mifepristone . from There have been no dose limiting toxicities ...AWARD NUMBER: W81XWH-14-1-0021 TITLE: A Pharmacokinetic/Pharmacodynamic Study of the Glucocorticoid Receptor Antagonist Mifepristone Combined...4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER A Pharmacokinetic/Pharmacodynamic Study of the Glucocorticoid Receptor Antagonist Mifepristone Combined

  9. A cannabinoid CB(1) receptor antagonist ameliorates impairment of recognition memory on withdrawal from MDMA (Ecstasy).

    Science.gov (United States)

    Nawata, Yoko; Hiranita, Takato; Yamamoto, Tsuneyuki

    2010-01-01

    (+/-)-3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') abusers have persistent neuropsychiatric deficits including memory impairments after the cessation of abuse. On the other hand, cannabinoid CB(1) receptors have been implicated in learning/memory, and are highly expressed in the hippocampus, a region of the brain believed to have an important function in certain forms of learning and memory. In this study, we clarified the mechanism underlying the cognitive impairment that develops during MDMA withdrawal from the standpoint of the cannabinoid CB(1) receptors. Mice were administered MDMA (10 mg/kg, i.p.) once a day for 7 days. On the 7th day of withdrawal, a novel object recognition task was performed and the amount of cannabinoid CB(1) receptor protein was measured with western blotting. Recognition performance was impaired on the 7th day of withdrawal. This impairment was blocked by AM251, a cannabinoid CB(1) receptor antagonist, administered 30 min before the training trial or co-administered with MDMA. At this time, the level of cannabinoid CB(1) receptor protein increased significantly in the hippocampus but not the prefrontal cortex or striatum. This increase of CB(1) receptor protein in the hippocampus was also blocked by the co-administration of AM251. Furthermore, CB(1) receptor knockout mice showed no impairment of recognition performance on the withdrawal from MDMA. The impairment of recognition memory during withdrawal from MDMA may result from the activation of cannabinoid CB(1) receptors in the hippocampus.

  10. Antagonist profile of ibodutant at the tachykinin NK2 receptor in guinea pig isolated bronchi.

    Science.gov (United States)

    Santicioli, Paolo; Meini, Stefania; Giuliani, Sandro; Lecci, Alessandro; Maggi, Carlo Alberto

    2013-10-24

    In this study we have characterized the pharmacological profile of the non-peptide tachykinin NK2 receptor antagonist ibodutant (MEN15596) in guinea pig isolated main bronchi contractility. The antagonist potency of ibodutant was evaluated using the selective NK2 receptor agonist [βAla(8)]NKA(4-10)-mediated contractions of guinea pig isolated main bronchi. In this assay ibodutant (30, 100 and 300nM) induced a concentration-dependent rightward shift of the [βAla(8)]NKA(4-10) concentration-response curves without affecting the maximal contractile effect. The analysis of the results yielded a Schild-plot linear regression with a slope not different from unity (0.95, 95% c.l. 0.65-1.25), thus indicating a surmountable behaviour. The calculated apparent antagonist potency as pKB value was 8.31±0.05. Ibodutant (0.3-100nM), produced a concentration-dependent inhibition of the nonadrenergic-noncholinergic (NANC) contractile response induced by electrical field stimulation (EFS) of intrinsic airway nerves in guinea pig isolated main bronchi. At the highest concentration tested (100nM) ibodutant almost abolished the EFS-induced bronchoconstriction (95±4% inhibition), the calculated IC50 value was 2.98nM (95% c.l. 1.73-5.16nM). In bronchi from ovalbumin (OVA) sensitized guinea pigs ibodutant (100nM) did not affect the maximal contractile response to OVA, but completely prevented the slowing in the fading of the motor response induced by phosphoramidon pretreatment linked to the endogenous neurokinin A release. Altogether, the present study demonstrate that ibodutant is a potent NK2 receptor antagonist in guinea pig airways.

  11. DEVELOPMENT OF NEW LHRH ANTAGONISTS

    Institute of Scientific and Technical Information of China (English)

    PENGDun-Ren; XIAOShao-Bo

    1989-01-01

    An ideal antagonist of LHRH is one which can act on the pitutary to inhibit LHRH-stimulatod LH / FSH secretion by competitive occupying the LHRH receptor in the pitutary gland. Its action should be very specific, fast and highly effective, the durations

  12. Synthesis and evaluation of novel angiotensin II receptor 1 antagonists as anti-hypertension drugs.

    Science.gov (United States)

    Bao, Xiaolu; Zhu, Weibo; Zhang, Ruijing; Wen, Caihong; Wang, Li; Yan, Yijia; Tang, Hesheng; Chen, Zhilong

    2016-05-01

    Three new angiotensin II receptor 1 antagonists, 1, 2 and 3 were designed, synthesized and evaluated. The AT1 receptor-binding assays in vitro showed that all the synthesized compounds had nanomolar affinity for the AT1 receptor. From which compound 3 was found to be the most potent ligands with an IC50 value of 2.67±0.23 nM. Biological evaluation in vivo revealed that all the compounds could cause significant decrease on MBP in a dose dependent manner in spontaneously hypertensive rats, and compound 3 especially showed an efficient and long-lasting effect in reducing blood pressure, whose maximal response lowered 41 mmHg of MBP at 10mg/kg and 62 mmHg at 15 mg/kg after oral administration, the significant anti-hypertensive effect lasted beyond 12 h, which is better than the reference compound losartan. The pharmacokinetic experiments showed that compound 3 could be absorbed efficiently and metabolized smoothly both in blood and in tissues in Wistar rats. The acute toxicity assay suggested that it has low toxicity with the LD50 value of 2974.35 mg/kg. These results demonstrate that compound 3 is a potent angiotensin AT1 receptor antagonist which could be considered as a novel anti-hypertension candidate and deserved for further investigation.

  13. Novel Toll-like receptor-4 antagonist (+)-naloxone protects mice from inflammation-induced preterm birth.

    Science.gov (United States)

    Chin, Peck Yin; Dorian, Camilla L; Hutchinson, Mark R; Olson, David M; Rice, Kenner C; Moldenhauer, Lachlan M; Robertson, Sarah A

    2016-11-07

    Toll-like receptor 4 (TLR4) activation by bacterial infection, or by sterile inflammatory insult is a primary trigger of spontaneous preterm birth. Here we utilize mouse models to investigate the efficacy of a novel small molecule TLR4 antagonist, (+)-naloxone, the non-opioid isomer of the opioid receptor antagonist (-)-naloxone, in infection-associated preterm birth. Treatment with (+)-naloxone prevented preterm delivery and alleviated fetal demise in utero elicited by i.p. LPS administration in late gestation. A similar effect with protection from preterm birth and perinatal death, and partial correction of reduced birth weight and postnatal mortality, was conferred by (+)-naloxone administration after intrauterine administration of heat-killed E. coli. Local induction by E. coli of inflammatory cytokine genes Il1b, Il6, Tnf and Il10 in fetal membranes was suppressed by (+)-naloxone, and cytokine expression in the placenta, and uterine myometrium and decidua, was also attenuated. These data demonstrate that inhibition of TLR4 signaling with the novel TLR4 antagonist (+)-naloxone can suppress the inflammatory cascade of preterm parturition, to prevent preterm birth and perinatal death. Further studies are warranted to investigate the utility of small molecule inhibition of TLR-driven inflammation as a component of strategies for fetal protection and delaying preterm birth in the clinical setting.

  14. Novel Toll-like receptor-4 antagonist (+)-naloxone protects mice from inflammation-induced preterm birth

    Science.gov (United States)

    Chin, Peck Yin; Dorian, Camilla L.; Hutchinson, Mark R.; Olson, David M.; Rice, Kenner C.; Moldenhauer, Lachlan M.; Robertson, Sarah A.

    2016-01-01

    Toll-like receptor 4 (TLR4) activation by bacterial infection, or by sterile inflammatory insult is a primary trigger of spontaneous preterm birth. Here we utilize mouse models to investigate the efficacy of a novel small molecule TLR4 antagonist, (+)-naloxone, the non-opioid isomer of the opioid receptor antagonist (−)-naloxone, in infection-associated preterm birth. Treatment with (+)-naloxone prevented preterm delivery and alleviated fetal demise in utero elicited by i.p. LPS administration in late gestation. A similar effect with protection from preterm birth and perinatal death, and partial correction of reduced birth weight and postnatal mortality, was conferred by (+)-naloxone administration after intrauterine administration of heat-killed E. coli. Local induction by E. coli of inflammatory cytokine genes Il1b, Il6, Tnf and Il10 in fetal membranes was suppressed by (+)-naloxone, and cytokine expression in the placenta, and uterine myometrium and decidua, was also attenuated. These data demonstrate that inhibition of TLR4 signaling with the novel TLR4 antagonist (+)-naloxone can suppress the inflammatory cascade of preterm parturition, to prevent preterm birth and perinatal death. Further studies are warranted to investigate the utility of small molecule inhibition of TLR-driven inflammation as a component of strategies for fetal protection and delaying preterm birth in the clinical setting. PMID:27819333

  15. Functional potencies of dopamine agonists and antagonists at human dopamine D₂ and D₃ receptors.

    Science.gov (United States)

    Tadori, Yoshihiro; Forbes, Robert A; McQuade, Robert D; Kikuchi, Tetsuro

    2011-09-01

    We measured the functional agonist potencies of dopamine agonists including antiparkinson drugs, and functional antagonist potencies of antipsychotics at human dopamine D(2) and D(3) receptors. In vitro pharmacological assessment included inhibition of forskolin-stimulated cAMP accumulation and the reversal of dopamine-induced inhibition in clonal Chinese hamster ovary cells expressing low and high densities of human dopamine D(2L) and D(2S) receptors (hD(2L)-Low, hD(2L)-High, hD(2S)-Low and hD(2S)-High, respectively) and human dopamine D(3) Ser-9 and D(3) Gly-9 receptors (hD(3)-Ser-9 and hD(3)-Gly-9, respectively). Cabergoline, bromocriptine, pergolide, (±)-7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT), talipexole, pramipexole, R-(+)-trans-3,4,4a,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano[4,3-b]-1,4-oxazin-9-olhydrochloride (PD128907) and ropinirole behaved as dopamine D(2) and D(3) receptor full agonists and showed higher potencies in hD(2L)-High and hD(2S)-High compared to hD(2L)-Low and hD(2S)-Low. In hD(3)-Ser-9 and hD(3)-Gly-9 compared to hD(2L)-Low and hD(2S)-Low, dopamine, ropinirole, PD128907, and pramipexole potencies were clearly higher; talipexole and 7-OH-DPAT showed slightly higher potencies; pergolide showed slightly lower potency; and, cabergoline and bromocriptine potencies were lower. Aripiprazole acted as an antagonist in hD(2L)-Low; a low intrinsic activity partial agonist in hD(2S)-Low; a moderate partial agonist in hD(3)-Ser-9 and hD(3)-Gly-9; a robust partial agonist in hD(2L)-High; and a full agonist in hD(2S)-High. Amisulpride, sulpiride and perphenazine behaved as preferential antagonists; and chlorpromazine and asenapine behaved as modest preferential antagonists; whereas fluphenazine, haloperidol, and blonanserin behaved as non-preferential antagonists in hD(2S)-Low and hD(2S)-High compared to hD(3)-Ser-9 and hD(3)-Gly-9. These findings may help to elucidate the basis of therapeutic benefit observed with these drugs, with

  16. Characterization of mechanisms involved in presynaptic inhibition of sympathetic pressor effects induced by some 5-HT1 receptor antagonists.

    Science.gov (United States)

    Fernández, M M; Calama, E; Morán, A; Martín, M L; San Román, L

    2000-01-01

    1. In a previous study, we showed that the presynaptic inhibitory action of 5-hydroxytryptamine receptor agonists on sympathetic pressor effects obtained in the pithed rats were mainly mediated by activation of 5-HT1A and 5-HT1D receptor subtypes. At the time, we observed that some 5-HT1 receptors antagonists - WAY 100,635 and NAN-190 (both 5-HT1A receptor antagonists), methiothepin (a 5-HT1,2,5,6,7 receptor antagonist) and spiperone (a 5-HT1,2 receptor antagonist) - reduced per se the pressor effects obtained by electrical stimulation. The aim of the present work was to investigate the mechanism participating in this inhibitory effect. 2. The inhibition induced by WAY 100,635 (1000 microg kg-1, i.v.) was blocked after i.v. treatment with idazoxan, an alpha2-adrenoceptor antagonist (300 and 1000 microg kg-1) and was not modified after i.v. treatment with propranolol, a beta-adrenoceptor antagonist (1000 microg kg-1) and sulpiride, a D2 receptor antagonist (1000 microg kg-1). The inhibition induced by spiperone (500 microg kg-1 i.v.) was significantly blocked by sulpiride (1000 microg kg-1) and was not modified by idazoxan or propranolol. 3. Sulpiride (1000 microg kg-1) partially blocked the inhibition induced by methiothepin (50 microg kg-1 i.v.). Only pretreatment with idazoxan (300 microg kg-1) modified the inhibition induced by NAN-190 (100 microg kg-1 i.v.), such inhibition increasing after intravenous administration of idazoxan. 4. All the antagonists used in our experiments failed to inhibit the pressor responses elicited by i.v. noradrenaline administration. 5. The above results suggest that the inhibitory effects of these 5-HT1 receptor antagonists are presynaptic in nature, but not related to the blockade of 5-HT1 receptors subtypes. The simultaneous activation or inhibition of other receptor systems could explain the inhibition produced by each 5-HT1 receptor antagonist studied.

  17. CRF receptor antagonist astressin-B reverses and prevents alopecia in CRF over-expressing mice.

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    Lixin Wang

    Full Text Available Corticotropin-releasing factor (CRF signaling pathways are involved in the stress response, and there is growing evidence supporting hair growth inhibition of murine hair follicle in vivo upon stress exposure. We investigated whether the blockade of CRF receptors influences the development of hair loss in CRF over-expressing (OE-mice that display phenotypes of Cushing's syndrome and chronic stress, including alopecia. The non-selective CRF receptors antagonist, astressin-B (5 µg/mouse injected peripherally once a day for 5 days in 4-9 months old CRF-OE alopecic mice induced pigmentation and hair re-growth that was largely retained for over 4 months. In young CRF-OE mice, astressin-B prevented the development of alopecia that occurred in saline-treated mice. Histological examination indicated that alopecic CRF-OE mice had hair follicle atrophy and that astressin-B revived the hair follicle from the telogen to anagen phase. However, astressin-B did not show any effect on the elevated plasma corticosterone levels and the increased weights of adrenal glands and visceral fat in CRF-OE mice. The selective CRF₂ receptor antagonist, astressin₂-B had moderate effect on pigmentation, but not on hair re-growth. The commercial drug for alopecia, minoxidil only showed partial effect on hair re-growth. These data support the existence of a key molecular switching mechanism triggered by blocking peripheral CRF receptors with an antagonist to reset hair growth in a mouse model of alopecia associated with chronic stress.

  18. Potential benefit from an H1-receptor antagonist on postexercise syncope in the heat.

    Science.gov (United States)

    McCord, Jennifer L; Pellinger, Thomas K; Lynn, Brenna M; Halliwill, John R

    2008-11-01

    H1-receptors mediate the early portion (i.e., first 30 min after exercise) of postexercise hypotension. Immediately after exercise, syncope can occur due to an exaggerated form of postexercise hypotension. Therefore, we hypothesized that orthostatic hypotension occurring immediately after exercise would be attenuated with an H1-receptor antagonist. We studied 15 endurance exercise-trained men and women in an environmental chamber set at 35 degrees C and 30.0% humidity. Subjects were studied in the supine position before a 45-min bout of treadmill running at 50% of VO2max. Immediately after exercise, measurements were taken in the supine position before the subjects were moved from a supine to a 60 degrees head-up tilt. Measurements included arterial pressure, heart rate, and brachial and cutaneous blood flow on a control and an H1-receptor antagonist (blockade) day. Mean arterial pressure was reduced 1 min into the tilt compared with preexercise values on the control day (76.2 +/- 0.5 vs 74.2 +/- 0.5 mm Hg; P 0.41). There were no differences in brachial vascular conductance (calculated as flow/pressure) in response to the head-up tilt between the study days (P > 0.23). The length of the head-up tilt was compared between study days for each subject. When contrasting this difference, the blockade lengthened the mean tilt time by 94 s (P = 0.098). These data suggest that an H1-receptor antagonist could potentially benefit postexercise syncope in a hot environment.

  19. Modification of Anxious Behavior after Psychogenic Trauma and Treatment with Galanin Receptor Antagonist.

    Science.gov (United States)

    Lyudyno, V I; Tsikunov, S G; Abdurasulova, I N; Kusov, A G; Klimenko, V M

    2015-07-01

    Effects of blockage of central galanin receptors on anxiety manifestations were studied in rats with psychogenic trauma. Psychogenic trauma was modeled by exposure of a group of rats to the situation when the partner was killed by a predator. Antagonist of galanin receptors was intranasally administered before stress exposure. Animal behavior was evaluated using the elevated-plus maze test, free exploratory paradigm, and open-field test. Psychogenic trauma was followed by an increase in anxiety level and appearance of agitated behavior. Blockage of galanin receptors aggravated behavioral impairment, which manifested in the pathological anxious reactions - manifestations of hypervigilance and hyperawareness. The results suggest that endogenous pool of galanin is involved into prevention of excessive CNS response to stressful stimuli typical of posttraumatic stress disorder.

  20. New trisubstituted 1,2,4-triazoles as ghrelin receptor antagonists.

    Science.gov (United States)

    Blayo, Anne-Laure; Maingot, Mathieu; Aicher, Babette; M'Kadmi, Céline; Schmidt, Peter; Müller, Gilbert; Teifel, Michael; Günther, Eckhard; Gagne, Didier; Denoyelle, Séverine; Martinez, Jean; Fehrentz, Jean-Alain

    2015-01-01

    Ghrelin receptor ligands based on a trisubstituted 1,2,4-triazole scaffold were recently synthesized and evaluated for their in vitro affinity for the GHS-R1a receptor and their biological activity. In this study, replacement of the α-aminoisobutyryl (Aib) moiety (a common feature present in numerous growth hormone secretagogues described in the literature) by aromatic and heteroaromatic groups was explored. We found potent antagonists incorporating the picolinic moiety in place of the Aib moiety. In an attempt to increase affinity and activity of our lead compound 2, we explored the modulation of the pyridine ring. Herein we report the design and the structure-activity relationships study of these new ghrelin receptor ligands.

  1. R-Smad competition controls activin receptor output in Drosophila.

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    Aidan J Peterson

    Full Text Available Animals use TGF-β superfamily signal transduction pathways during development and tissue maintenance. The superfamily has traditionally been divided into TGF-β/Activin and BMP branches based on relationships between ligands, receptors, and R-Smads. Several previous reports have shown that, in cell culture systems, "BMP-specific" Smads can be phosphorylated in response to TGF-β/Activin pathway activation. Using Drosophila cell culture as well as in vivo assays, we find that Baboon, the Drosophila TGF-β/Activin-specific Type I receptor, can phosphorylate Mad, the BMP-specific R-Smad, in addition to its normal substrate, dSmad2. The Baboon-Mad activation appears direct because it occurs in the absence of canonical BMP Type I receptors. Wing phenotypes generated by Baboon gain-of-function require Mad, and are partially suppressed by over-expression of dSmad2. In the larval wing disc, activated Baboon cell-autonomously causes C-terminal Mad phosphorylation, but only when endogenous dSmad2 protein is depleted. The Baboon-Mad relationship is thus controlled by dSmad2 levels. Elevated P-Mad is seen in several tissues of dSmad2 protein-null mutant larvae, and these levels are normalized in dSmad2; baboon double mutants, indicating that the cross-talk reaction and Smad competition occur with endogenous levels of signaling components in vivo. In addition, we find that high levels of Activin signaling cause substantial turnover in dSmad2 protein, providing a potential cross-pathway signal-switching mechanism. We propose that the dual activity of TGF-β/Activin receptors is an ancient feature, and we discuss several ways this activity can modulate TGF-β signaling output.

  2. Radiolabeling with fluorine-18 of a protein, interleukin-1 receptor antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Prenant, C., E-mail: cprenant@cyclopharma.f [Wolfson Molecular Imaging Centre, University of Manchester, Manchester (United Kingdom); Cawthorne, C. [Academic Department of Radiation Oncology, Christie NHS Foundation Trust, Manchester (United Kingdom); Fairclough, M. [Wolfson Molecular Imaging Centre, University of Manchester, Manchester (United Kingdom); Rothwell, N.; Boutin, H. [Faculty of Life Sciences, University of Manchester, Manchester (United Kingdom)

    2010-09-15

    IL-1RA is a naturally occurring antagonist of the pro-inflammatory cytokine interleukin-1 (IL-1) with high therapeutic promise, but its pharmacokinetic remains poorly documented. In this report, we describe the radiolabeling of recombinant human interleukin-1 receptor antagonist (rhIL-1RA) with fluorine-18 to allow pharmacokinetic studies by positron emission tomography (PET). rhIL-1RA was labeled randomly by reductive alkylation of free amino groups (the {epsilon}-amino group of lysine residues or amino-terminal residues) using [{sup 18}F]fluoroacetaldehyde under mild reaction conditions. Radiosyntheses used a remotely controlled experimental rig within 100 min and the radiochemical yield was in the range 7.1-24.2% (decay corrected, based on seventeen syntheses). We showed that the produced [{sup 18}F]fluoroethyl-rhIL-1ra retained binding specificity by conducting an assay on rat brain sections, allowing its pharmakokinetic study using PET.

  3. [Antagonists of the type 3 serotonin receptor (5 -HT3) in IBS].

    Science.gov (United States)

    Komoto, Shunsuke; Miura, Soichiro

    2006-08-01

    Irritable bowel syndrome (IBS) is a common chronic gastrointestinal (GI) disorder, but its pathophysiology remains unknown. 5-hydroxytryptamine (5-HT, serotonin) is an important neurotransmitter involved in the brain-gut connection. Alosetron, a 5-HT3 receptor antagonist, has been demonstrated in randomized, placebo-controlled trials (RCT) to be effective in diarrhea-predominant IBS(IBS-D). Constipation is the most common adverse event. Alosetron improved abdominal pain and discomfort and stool consistency in both female and male patients, but it did not improve other symptoms (sense of urgency, stool frequency and bloating) in male patients. Although less is known about the gender differences in therapeutic benefit, a new 5-HT3 antagonist, cilansetron, has demonstrated effectiveness in male and female IBS-D patients and is currently under clinical trials.

  4. Predicting the relative binding affinity of mineralocorticoid receptor antagonists by density functional methods

    Science.gov (United States)

    Roos, Katarina; Hogner, Anders; Ogg, Derek; Packer, Martin J.; Hansson, Eva; Granberg, Kenneth L.; Evertsson, Emma; Nordqvist, Anneli

    2015-12-01

    In drug discovery, prediction of binding affinity ahead of synthesis to aid compound prioritization is still hampered by the low throughput of the more accurate methods and the lack of general pertinence of one method that fits all systems. Here we show the applicability of a method based on density functional theory using core fragments and a protein model with only the first shell residues surrounding the core, to predict relative binding affinity of a matched series of mineralocorticoid receptor (MR) antagonists. Antagonists of MR are used for treatment of chronic heart failure and hypertension. Marketed MR antagonists, spironolactone and eplerenone, are also believed to be highly efficacious in treatment of chronic kidney disease in diabetes patients, but is contra-indicated due to the increased risk for hyperkalemia. These findings and a significant unmet medical need among patients with chronic kidney disease continues to stimulate efforts in the discovery of new MR antagonist with maintained efficacy but low or no risk for hyperkalemia. Applied on a matched series of MR antagonists the quantum mechanical based method gave an R2 = 0.76 for the experimental lipophilic ligand efficiency versus relative predicted binding affinity calculated with the M06-2X functional in gas phase and an R2 = 0.64 for experimental binding affinity versus relative predicted binding affinity calculated with the M06-2X functional including an implicit solvation model. The quantum mechanical approach using core fragments was compared to free energy perturbation calculations using the full sized compound structures.

  5. Inverse antagonist activities of parabens on human oestrogen-related receptor γ (ERRγ): In vitro and in silico studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhaobin; Sun, Libei; Hu, Ying; Jiao, Jian; Hu, Jianying, E-mail: hujy@urban.pku.edu.cn

    2013-07-01

    Parabens are p-hydroxybenzoic acid esters that have been used extensively as preservatives in foods, cosmetics, drugs and toiletries. These intact esters are commonly detected in human breast cancer tissues and other human samples, thus arousing concern about the involvement of parabens in human breast cancer. In this study, an in vitro nuclear receptor coactivator recruiting assay was developed and used to evaluate the binding activities of parabens, salicylates and benzoates via antagonist competitive binding on the human oestrogen-related receptor γ (ERRγ), which is known as both a diagnostic biomarker and a treatment target of breast cancer. The results showed that all of the test parabens (methyl-, ethyl-, propyl-, butyl- and benzylparaben) possessed clear inverse antagonist activities on ERRγ, with a lowest observed effect level (LOEL) of 10{sup −7} M and the 50% relative effective concentrations (REC50) varying from 3.09 × 10{sup −7} to 5.88 × 10{sup −7} M, whereas the salicylates possessed much lower activities and the benzoates showed no obvious activity. In silico molecular docking analyses showed that parabens fitted well into the active site of ERRγ, with hydrogen bonds forming between the p-hydroxyl group of parabens and the Glu275/Arg316 of ERRγ. As the paraben levels reported in breast cancer tissues are commonly higher than the LOELs observed in this study, parabens may play some role via ERRγ in the carcinogenesis of human breast cancer. In addition, parabens may have significant effects on breast cancer patients who are taking tamoxifen, as ERRγ is regarded as a treatment target for tamoxifen. - Highlights: • An oestrogen-related receptor γ coactivator recruiting assay was developed. • Strong binding activities of parabens with oestrogen-related receptor γ were found. • The paraben levels reported in breast cancer tissues were higher than their LOELs. • Parabens may play some role via ERRγ in the carcinogenesis of human

  6. Identification of functional bitter taste receptors and their antagonist in chickens.

    Science.gov (United States)

    Dey, Bapon; Kawabata, Fuminori; Kawabata, Yuko; Yoshida, Yuta; Nishimura, Shotaro; Tabata, Shoji

    2017-01-22

    Elucidation of the taste sense of chickens is important not only for the development of chicken feedstuffs for the chicken industry but also to help clarify the evolution of the taste sense among animals. There are three putative chicken bitter taste receptors, chicken T2R1 (cT2R1), cT2R2 and cT2R7, which were identified using genome information and cell-based assays. Previously, we have shown that cT2R1 is a functional bitter taste receptor through both cell-based assays and behavioral tests. In this study, therefore, we focused on the sensitivities of the other two bitter receptors, cT2R2 and cT2R7, by using their agonists in behavioral tests. We tested three agonists of cT2R2 and three agonists of cT2R7. In a 10-min drinking study, the intakes of cT2R2 agonist solutions were not different from that of water. On the other hand, the intakes of cT2R7 agonist solutions were significantly lower compared to water. In addition, we constructed cT2R1-and cT2R7-expressing cells in order to search for an antagonist for these functional bitter taste receptors. By using Ca(2+) imaging methods, we found that 6-methoxyflavanone (6-meth) can inhibit the activities of both cT2R1 and cT2R7. Moreover, 6-meth also inhibited the reduction of the intake of bitter solutions containing cT2R1 or cT2R7 agonists in behavioral tests. Taken together, these results suggested that cT2R7 is a functional bitter taste receptor like cT2R1, but that cT2R2 is not, and that 6-meth is an antagonist for these two functional chicken bitter taste receptors. This is the first identification of an antagonist of chicken bitter receptors. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. AM-251 and rimonabant act as direct antagonists at mu-opioid receptors: implications for opioid/cannabinoid interaction studies.

    Science.gov (United States)

    Seely, Kathryn A; Brents, Lisa K; Franks, Lirit N; Rajasekaran, Maheswari; Zimmerman, Sarah M; Fantegrossi, William E; Prather, Paul L

    2012-10-01

    Mu-opioid and CB1-cannabinoid agonists produce analgesia; however, adverse effects limit use of drugs in both classes. Additive or synergistic effects resulting from concurrent administration of low doses of mu- and CB1-agonists may produce analgesia with fewer side effects. Synergism potentially results from interaction between mu-opioid receptors (MORs) and CB1 receptors (CB1Rs). AM-251 and rimonabant are CB1R antagonist/inverse agonists employed to validate opioid-cannabinoid interactions, presumed to act selectively at CB1Rs. Therefore, the potential for direct action of these antagonists at MORs is rarely considered. This study determined if AM-251 and/or rimonabant directly bind and modulate the function of MORs. Surprisingly, AM-251 and rimonabant, but not a third CB1R inverse agonist AM-281, bind with mid-nanomolar affinity to human MORs with a rank order of affinity (K(i)) of AM-251 (251 nM) > rimonabant (652 nM) > AM281 (2135 nM). AM-251 and rimonabant, but not AM-281, also competitively antagonize morphine induced G-protein activation in CHO-hMOR cell homogenates (K(b) = 719 or 1310 nM, respectively). AM-251 and rimonabant block morphine inhibition of cAMP production, while only AM-251 elicits cAMP rebound in CHO-hMOR cells chronically exposed to morphine. AM-251 and rimonabant (10 mg/kg) attenuate morphine analgesia, whereas the same dose of AM-281 produces little effect. Therefore, in addition to high CB1R affinity, AM-251 and rimonabant bind to MORs with mid-nanomolar affinity and at higher doses may affect morphine analgesia via direct antagonism at MORs. Such CB1-independent of these antagonists effects may contribute to reported inconsistencies when CB1/MOR interactions are examined via pharmacological methods in CB1-knockout versus wild-type mice.

  8. Lack of Association Between IL-1 Receptor Antagonist Gene 86bp VNTR Polymorphism and Leiomyoma

    Directory of Open Access Journals (Sweden)

    Mohammadoo Khorasani

    2014-04-01

    Full Text Available Background Uterine leiomyoma (ULs is the most common gynecological tumor and a significant health concern for many women .The interleukin-1 receptor antagonist (IL-1Ra is a naturally occurring cytokine inhibiting interleukin- 1 (IL-1 activity by binding to the IL-1 receptors without signal transduction. Objectives The aim of this study was to investigate the association between interleukin-1 receptor antagonist gene variable number of tandem repeat (VNTR polymorphism and ULs in women of the South- East of Iran. Patients and Methods A total number of 99 patients with leiomyoma and 102 controls were studied. Genotyping of IL-1Ra (VNTR polymorphism was determined by gel electrophoresis after PCR amplification. Frequency of alleles and genotypes in patients and control group was statistically analyzed using χ2 test or fisher exact test. Results The frequency of alleles 1, 2 and 3 of IL-1Ra VNTR polymorphism were %71, %27 and %22 in control group and %74, %20 and %6 in the ULs patients, respectively and there were no significant differences between these two groups. No statistically significant differences were observed between the frequency of IL-1Ra genotypes in the study and control groups. Conclusions This study showed that 86bp VNTR polymorphism of IL-1Ra gene is not associated with leiomyoma in the studied population.

  9. Triazoloquinazolines as Human A3 Adenosine Receptor Antagonists: A QSAR Study

    Directory of Open Access Journals (Sweden)

    Dae-Sil Lee

    2006-11-01

    Full Text Available Multiple linear regression analysis was performed on the quantitative structure-activity relationships (QSAR of the triazoloquinazoline adenosine antagonists for human A3receptors. The data set used for the QSAR analysis encompassed the activities of 33triazoloquinazoline derivatives and 72 physicochemical descriptors. A template moleculewas derived using the known molecular structure for one of the compounds when bound tothe human A2B receptor, in which the amide bond was in a cis-conformation. All the testcompounds were aligned to the template molecule. In order to identify a reasonable QSARequation to describe the data set, we developed a multiple linear regression program thatexamined every possible combination of descriptors. The QSAR equation derived from thisanalysis indicates that the spatial and electronic effects is greater than that of hydrophobiceffects in binding of the antagonists to the human A3 receptor. It also predicts that a largesterimol length parameter is advantageous to activity, whereas large sterimol widthparameters and fractional positive partial surface areas are nonadvatageous.

  10. Salvianolic Acid A, as a Novel ETA Receptor Antagonist, Shows Inhibitory Effects on Tumor in Vitro.

    Science.gov (United States)

    Zhang, Qiao; Wang, Shifeng; Yu, Yangyang; Sun, Shengnan; Zhang, Yuxin; Zhang, Yanling; Yang, Wei; Li, Shiyou; Qiao, Yanjiang

    2016-08-02

    Endothelin-1 (ET-1) autocrine and paracrine signaling modulate cell proliferation of tumor cells by activating its receptors, endothelin A receptor (ETAR) and endothelin B receptor (ETBR). Dysregulation of ETAR activation promotes tumor development and progression. The potential of ETAR antagonists and the dual-ETAR and ETBR antagonists as therapeutic approaches are under preclinical and clinical studies. Salvianolic acid A (Sal A) is a hydrophilic polyphenolic derivative isolated from Salvia miltiorrhiza Bunge (Danshen), which has been reported as an anti-cancer and cardio-protective herbal medicine. In this study, we demonstrate that Sal A inhibits ETAR activation induced by ET-1 in both recombinant and endogenous ETAR expression cell lines. The IC50 values were determined as 5.7 µM in the HEK293/ETAR cell line and 3.14 µM in HeLa cells, respectively. Furthermore, our results showed that Sal A suppressed cell proliferation and extended the doubling times of multiple cancer cells, including HeLa, DU145, H1975, and A549 cell lines. In addition, Sal A inhibited proliferation of DU145 cell lines stimulated by exogenous ET-1 treatment. Moreover, the cytotoxicity and cardio-toxicity of Sal A were assessed in human umbilical vein endothelial cells (HUVEC) and Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), which proved that Sal A demonstrates no cytotoxicity or cardiotoxicity. Collectively, our findings indicate that Sal A is a novel anti-cancer candidate through targeting ETAR.

  11. 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.

  12. Lower lid entropion secondary to treatment with alpha-1a receptor antagonist: a case report

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    Simcock Peter

    2010-03-01

    Full Text Available Abstract Introduction The use of alpha-1a receptor antagonists (tamsulosin is widely accepted in the treatment of benign prostatic hypertrophy (BPH. It has previously been implicated as a causative agent in intra-operative floppy iris syndrome due to its effects on the smooth muscle. We report a case of lower lid entropion that may be related to a patient commencing treatment of tamsulosin. Case presentation A 74-year-old Caucasian man was started on alpha 1-a receptor antagonist (Tamsulosin treatment for benign prostatic hypertrophy. Eight days later, he presented to the ophthalmology unit with a right lower lid entropion which was successfully treated surgically with a Weiss procedure. Conclusion We report a case of lower lid entropion that may be secondary to the recent use of an alpha-1a blocker (tamsulosin. This can be explained by considering the effect of autonomic blockade on alpha-1 receptors in the Muller's muscle on a patient that may already have an anatomical predisposition to entropion formation due to a further reduction in muscle tone.

  13. Discovery of novel protease activated receptors 1 antagonists with potent antithrombotic activity in vivo.

    Science.gov (United States)

    Perez, Michel; Lamothe, Marie; Maraval, Catherine; Mirabel, Etienne; Loubat, Chantal; Planty, Bruno; Horn, Clemens; Michaux, Julien; Marrot, Sebastien; Letienne, Robert; Pignier, Christophe; Bocquet, Arnaud; Nadal-Wollbold, Florence; Cussac, Didier; de Vries, Luc; Le Grand, Bruno

    2009-10-08

    Protease activated receptors (PARs) or thrombin receptors constitute a class of G-protein-coupled receptors (GPCRs) implicated in the activation of many physiological mechanisms. Thus, thrombin activates many cell types such as vascular smooth muscle cells, leukocytes, endothelial cells, and platelets via activation of these receptors. In humans, thrombin-induced platelet aggregation is mediated by one subtype of these receptors, termed PAR1. This article describes the discovery of new antagonists of these receptors and more specifically two compounds: 2-[5-oxo-5-(4-pyridin-2-ylpiperazin-1-yl)penta-1,3-dienyl]benzonitrile 36 (F 16618) and 3-(2-chlorophenyl)-1-[4-(4-fluorobenzyl)piperazin-1-yl]propenone 39 (F 16357), obtained after optimization. Both compounds are able to inhibit SFLLR-induced human platelet aggregation and display antithrombotic activity in an arteriovenous shunt model in the rat after iv or oral administration. Furthermore, these compounds are devoid of bleeding side effects often observed with other types of antiplatelet drugs, which constitutes a promising advantage for this new class of antithrombotic agents.

  14. Novel histamine H3 receptor antagonists: affinities in an H3 receptor binding assay and potencies in two functional H3 receptor models.

    OpenAIRE

    Schlicker, E.; Kathmann, M; Reidemeister, S.; Stark, H.; Schunack, W

    1994-01-01

    1. We determined the affinities of ten novel H3 receptor antagonists in an H3 receptor binding assay and their potencies in two functional H3 receptor models. The novel compounds differ from histamine in that the aminoethyl side chain is replaced by a propyl or butyl chain linked to a polar group (amide, thioamide, ester, guanidine, guanidine ester or urea) which, in turn, is connected to a hexocyclic ring or to an alicyclic ring-containing alkyl residue [corrected]. 2. The specific binding o...

  15. Adenosine A2A receptor binding profile of two antagonists, ST1535 and KW6002: consideration on the presence of atypical adenosine A2A binding sites

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    Teresa Riccioni

    2010-08-01

    Full Text Available Adenosine A2A receptors seem to exist in typical (more in striatum and atypical (more in hippocampus and cortex subtypes. In the present study, we investigated the affinity of two adenosine A2A receptor antagonists, ST1535 [2 butyl -9-methyl-8-(2H-1,2,3-triazol 2-yl-9H-purin-6-xylamine] and KW6002 [(E-1,3-diethyl-8-(3,4-dimethoxystyryl-7-methyl-3,7-dihydro-1H-purine-2,6,dione] to the “typical” and “atypical” A2A binding sites. Affinity was determined by radioligand competition experiments in membranes from rat striatum and hippocampus. Displacement of the adenosine analog [3H]CGS21680 [2-p-(2-carboxyethylphenethyl-amino-5’-N-ethylcarbox-amidoadenosine] was evaluated in the absence or in the presence of either CSC [8-(3-chlorostyryl-caffeine], an adenosine A2A antagonist that pharmacologically isolates atypical binding sites, or DPCPX (8-cyclopentyl-1,3-dipropylxanthine, an adenosine A1 receptor antagonist that pharmacologically isolates typical binding site. ZM241385 [84-(2-[7-amino-2-(2-furyl [1,2,4]-triazol[2,3-a][1,3,5]triazin-5-yl amino]ethyl phenol] and SCH58261 [(5-amino-7-(β-phenylethyl-2-(8-furylpyrazolo(4,3-e-1,2,4-triazolo(1,5-c pyrimidine], two other adenosine A2A receptor antagonists, which were reported to differently bind to atypical and typical A2A receptors, were used as reference compounds. ST1535, KW6002, ZM241385 and SCH58261 displaced [3H]CGS21680 with higher affinity in striatum than in hippocampus. In hippocampus, no typical adenosine A2A binding was detected, and ST1535 was the only compound that occupied atypical A2A adenosine receptors. Present data are explained in terms of heteromeric association among adenosine A2A, A2B and A1 receptors, rather than with the presence of atypical A2A receptor subtype.

  16. [3H]A-804598 ([3H]2-cyano-1-[(1S)-1-phenylethyl]-3-quinolin-5-ylguanidine) is a novel, potent, and selective antagonist radioligand for P2X7 receptors.

    Science.gov (United States)

    Donnelly-Roberts, Diana L; Namovic, Marian T; Surber, Bruce; Vaidyanathan, Srirajan X; Perez-Medrano, Arturo; Wang, Ying; Carroll, William A; Jarvis, Michael F

    2009-01-01

    ATP-sensitive P2X7 receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X7 receptors leads to rapid changes in intracellular calcium concentrations, release of the pro-inflammatory cytokine IL-1beta, and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Data from gene knockout studies and recently described selective antagonists indicate a role for P2X7 receptor activation in inflammation and pain. While several species selective P2X7 antagonists exist, A-804598 represents a structurally novel, competitive, and selective antagonist that has equivalent high affinity at rat (IC50 = 10 nM), mouse (IC50 = 9 nM) and human (IC50 = 11 nM) P2X7 receptors. A-804598 also potently blocked agonist stimulated release of IL-1beta and Yo-Pro uptake from differentiated THP-1 cells that natively express human P2X7 receptors. A-804598 was tritiated ([3H]A-804598; 8.1Ci/mmol) and utilized to study recombinant rat P2X7 receptors expressed in 1321N1 cells. [3H]A-804598 labeled a single class of high affinity binding sites (Kd=2.4 nM and apparent Bmax=0.56 pmol/mg). No specific binding was observed in untransfected 1321N1 cells. The pharmacological profile for P2X antagonists to inhibit [3H]A-804598 binding correlated with their ability to block functional activation of P2X7 receptors (r=0.95, PP2X7 receptors described to date and [3H]A-804598 is a high affinity antagonist radioligand that specifically labels rat P2X7 receptors.

  17. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    Science.gov (United States)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-04-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1-3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.

  18. Novel Method for Synthesis of Diarylpyrazole Derivatives as Cannabinoid CB1 Receptor Antagonists

    Institute of Scientific and Technical Information of China (English)

    WU Ying-qiu; ZHENG Guo-jun; WANG Ya-ping; WANG Xiang-jing; XIANG Wen-sheng

    2011-01-01

    A novel and efficient method was developed for the synthesis of diarylpyrazole derivatives as cannabinoid CB1 receptor antagonist via four step reactions. The key step was the synthesis of a diarylpyrazole skeleton, which involved initial condensation of the sodium salt of compound 12 with diazonium compounds, and further cyclization by heating at reflux in acetic acid. Eight diarylpyrazole derivatives and nine new synthesized compounds were cha racterized by 1H NMRy IR, MS, and elemental analysis. The reaction conditions were mild and the overall yields of the target compounds ranged from 26% to 44%.

  19. Interleukin-1 receptor antagonist decreases bone loss and bone resorption in ovariectomized rats.

    OpenAIRE

    Kimble, R B; Vannice, J L; Bloedow, D C; Thompson, R.C.; Hopfer, W; Kung, V T; Brownfield, C; Pacifici, R

    1994-01-01

    Interleukin-1 (IL-1), a cytokine produced by bone marrow cells and bone cells, has been implicated in the pathogenesis of postmenopausal osteoporosis because of its potent stimulatory effects on bone resorption in vitro and in vivo. To investigate whether IL-1 plays a direct causal role in post ovariectomy bone loss, 6-mo-old ovariectomized rats were treated with subcutaneous infusions of IL-1 receptor antagonist (IL-1ra), a specific competitor of IL-1, for 4 wk, beginning either at the time ...

  20. NO in exhaled air of asthmatic children is reduced by the leukotriene receptor antagonist montelukast

    DEFF Research Database (Denmark)

    Bisgaard, H; Loland, L; Oj, J A

    1999-01-01

    Nitric oxide in exhaled air (FENO) is increased in asthmatic children, probably reflecting aspects of airway inflammation. We have studied the effect of the leukotriene receptor antagonist (LTRA) montelukast on FENO with a view to elucidate potential anti-inflammatory properties of LTRAs. Twenty......-six asthmatic children 6 to 15 yr of age completed a double-blind crossover trial of 2 wk of treatment with 5 mg montelukast once daily versus placebo. FENO was measured during single-breath exhalation at a constant flow rate of 0.1 to 0.13 L/s against a resistance of 10 kPa/L/s. Eleven children were receiving...

  1. The discovery of quinoline based single-ligand human H1 and H3 receptor antagonists.

    Science.gov (United States)

    Procopiou, Panayiotis A; Ancliff, Rachael A; Gore, Paul M; Hancock, Ashley P; Hodgson, Simon T; Holmes, Duncan S; Keeling, Steven P; Looker, Brian E; Parr, Nigel A; Rowedder, James E; Slack, Robert J

    2016-12-15

    A novel series of potent quinoline-based human H1 and H3 bivalent histamine receptor antagonists, suitable for intranasal administration for the potential treatment of allergic rhinitis associated nasal congestion, were identified. Compound 18b had slightly lower H1 potency (pA2 8.8 vs 9.7 for the clinical goldstandard azelastine), and H3 potency (pKi 9.1vs 6.8 for azelastine), better selectivity over α1A, α1B and hERG, similar duration of action, making 18b a good back-up compound to our previous candidate, but with a more desirable profile.

  2. The Antiinflammatory Cytokine Interleukin-1 Receptor Antagonist Protects from High-Fat Diet-Induced Hyperglycemia

    OpenAIRE

    Sauter, Nadine S; Fabienne T Schulthess; Galasso, Ryan; Castellani, Lawrence W.; Maedler, Kathrin

    2008-01-01

    Subclinical inflammation is a recently discovered phenomenon in type 2 diabetes. Elevated cytokines impair β-cell function and survival. A recent clinical trial shows that blocking IL-1β signaling by IL-1 receptor antagonist (IL-1Ra) improves β-cell secretory function in patients with type 2 diabetes. In the present study, we provide further mechanisms of the protective role of IL-1Ra on the β-cell. IL-1Ra prevented diabetes in vivo in C57BL/6J mice fed a high-fat/high-sucrose diet (HFD) for ...

  3. Hydroxylated analogues of 5-aminovaleric acid as 4-aminobutyric acidB receptor antagonists

    DEFF Research Database (Denmark)

    Kristiansen, U; Hedegaard, A; Herdeis, C;

    1992-01-01

    The (R) and (S) forms of 5-amino-2-hydroxyvaleric acid (2-OH-DAVA) and 5-amino-4-hydroxyvaleric acid (4-OH-DAVA) were designed as structural hybrids of the 4-aminobutyric acidB (GABAB) agonist (R)-(-)-4-amino-3-hydroxybutyric acid [(R)-(-)-3-OH-GABA] and the GABAB antagonist 5-aminovaleric acid....... All four compounds were weak inhibitors of GABAA receptor binding in rat brain, and none of them significantly affected synaptosomal GABA uptake. Based on molecular modeling studies it has been demonstrated that low-energy conformations of (R)-(-)-3-OH-GABA, (S)-(-)-2-OH-DAVA, and (R)-(-)-4-OH...

  4. Unusual pyrimidine participation: efficient stereoselective synthesis of potent dual orexin receptor antagonist MK-6096.

    Science.gov (United States)

    Chung, John Y L; Zhong, Yong-Li; Maloney, Kevin M; Reamer, Robert A; Moore, Jeffrey C; Strotman, Hallena; Kalinin, Alexei; Feng, Ronnie; Strotman, Neil A; Xiang, Bangping; Yasuda, Nobuyoshi

    2014-11-21

    An asymmetric synthesis of dual orexin receptor antagonist MK-6096 (1) is described. Key steps for the trans-2,5-disubstituted piperidinyl ether fragment include a biocatalytic transamination, a trans-selective Mukaiyama aldol, and a regioselective pyridyl SNAr process. The pyrimidyl benzoic acid was synthesized via a Negishi coupling and a nitrile hydrolysis. Coupling of the two fragments via a catalytic T3P-mediated amidation completed the synthesis. Unusual behaviors in the hydrolysis of pyrimidyl benzonitrile and the amide coupling of the pyrimidyl benzoic acid are also described.

  5. Comparison of the effects of the M1-receptor antagonist telenzepine and the CCK-receptor antagonist loxiglumide on the pancreatic secretory response to intraduodenal tryptophan in dogs.

    Science.gov (United States)

    Teyssen, S; Niebergall-Roth, E; Rausch, A; Beglinger, C; Riepl, R L; Chari, S; Singer, M V

    1996-11-01

    In six conscious dogs with chronic gastric and pancreatic fistulas we compared the action of different doses (20.25 to 81.0 nmol/kg/h) of the muscarinic M1-receptor antagonist telenzepine, the cholecystokinin (CCK) antagonist loxiglumide (2.5 to 10.0 mg/kg/h) and several combinations of both drugs on the pancreatic secretory response to intraduodenal perfusion of graded loads of tryptophan (0.37-10.0 mmol/h) given against a background of secretin (20.5 pmol/kg/h i.v.). Except for 20.25 nmol/kg/h telenzepine, all tested doses of telenzepine and/or loxiglumide decreased the 180-min integrated bicarbonate response to tryptophan by 55 to 119%. Except of 20.25 nmol/kg/h telenzepine and/or 2.5 mg/kg/h loxiglumide, all tested doses of telezepine and/or loxiglumide inhibited the tryptophan stimulated integrated pancreatic protein responses by 54 to 88%. While telenzepine mainly inhibited the bicarbonate and protein response to the lower loads of tryptophan (0.37-1.1 mmol/h), loxiglumide decreased the response to all loads of tryptophan. The inhibition evoked by the combinations of telenzepine and loxiglumide was not significantly greater than that by single infusion of either drug. The CCK plasma levels basally and in response to tryptophan were not significantly altered by telenzepine and/or loxiglumide. These findings indicate that (1) both enteropancreatic cholinergic reflexes and the hormone CCK are mediators of the protein response to intraduodenal trytophan (2) enteropancreatic cholinergic reflexes are probably the dominant mediators of the response to low amounts of tryptophan, whereas CCK is the major mediator of the response to high loads of tryptophan, (3) the two mediators seem to act independently of each other, and (4) the release of CCK by intestinal trytophan is not influenced by telenzepine or loxiglumide.

  6. Casopitant: a novel NK(1)-receptor antagonist in the prevention of chemotherapy-induced nausea and vomiting

    DEFF Research Database (Denmark)

    Ruhlmann, Christina; Herrstedt, Jørn

    2009-01-01

    , whereas the effect on nausea seems to be limited. The first NK(1) receptor antagonist, aprepitant, became clinically available in 2003, and casopitant, the second in this class of antiemetics, has now completed phase III trials. This review delineates the properties and clinical use of casopitant......-hydroxytryptamine (5-HT)(3)- and neurokinin (NK)(1) receptors in the emetic reflex arch. This has led to the development of two new classes of antiemetics acting as highly selective antagonists at one of these receptors. These drugs have had a huge impact in the protection from chemotherapy-induced vomiting...

  7. Discovery of CC chemokine receptor-3 (CCR3) antagonists with picomolar potency.

    Science.gov (United States)

    De Lucca, George V; Kim, Ui Tae; Vargo, Brian J; Duncia, John V; Santella, Joseph B; Gardner, Daniel S; Zheng, Changsheng; Liauw, Ann; Wang, Zhang; Emmett, George; Wacker, Dean A; Welch, Patricia K; Covington, Maryanne; Stowell, Nicole C; Wadman, Eric A; Das, Anuk M; Davies, Paul; Yeleswaram, Swamy; Graden, Danielle M; Solomon, Kimberly A; Newton, Robert C; Trainor, George L; Decicco, Carl P; Ko, Soo S

    2005-03-24

    Starting with our previously described(20) class of CC chemokine receptor-3 (CCR3) antagonist, we improved the potency by replacing the phenyl linker of 1 with a cyclohexyl linker and by replacing the 4-benzylpiperidine with a 3-benzylpiperidine. The resulting compound, 32, is a potent and selective antagonist of CCR3. SAR studies showed that the 3-acetylphenyl urea of 32 could be replaced with heterocyclic ureas or heterocyclic-substituted phenyl ureas and still maintain the potency (inhibition of eotaxin-induced chemotaxis) of this class of compounds in the low-picomolar range (IC(50) = 10-60 pM), representing some of the most potent CCR3 antagonists reported to date. The potency of 32 for mouse CCR3 (chemotaxis IC(50) = 41 nM) and its oral bioavailability in mice (20% F ) were adequate to assess the efficacy in animal models of allergic airway inflammation. Oral administration of 32 reduced eosinophil recruitment into the lungs in a dose-dependent manner in these animal models. On the basis of its overall potency, selectivity, efficacy, and safety profile, the benzenesulfonate salt of 32, designated DPC168, entered phase I clinical trials.

  8. Procognitive properties of drugs with single and multitargeting H3 receptor antagonist activities.

    Science.gov (United States)

    Nikolic, Katarina; Filipic, Slavica; Agbaba, Danica; Stark, Holger

    2014-07-01

    The histamine H3 receptor (H3 R) is an important modulator of numerous central control mechanisms. Novel lead optimizations for H3 R antagonists/inverse agonists involved studies of structure-activity relationships, cross-affinities, and pharmacokinetic properties of promising ligands. Blockade of inhibitory histamine H3 autoreceptors reinforces histaminergic transmission, while antagonism of H3 heteroreceptors accelerates the corticolimbic liberation of acetylcholine, norepinephrine, glutamate, dopamine, serotonin and gamma-aminobutyric acid (GABA). The H3 R positioned at numerous neurotransmission crossroads indicates therapeutic applications of small-molecule H3 R modulators in a number of psychiatric and neurodegenerative diseases with various clinical candidates available. Dual target drugs displaying H3 R antagonism/inverse agonism with inhibition of acetylcholine esterase (AChE), histamine N-methyltransferase (HMT), or serotonin transporter (SERT) are novel class of procognitive agents. Main chemical diversities, pharmacophores, and pharmacological profiles of procognitive agents acting as H3 R antagonists/inverse agonists and dual H3 R antagonists/inverse agonists with inhibiting activity on AChE, HMT, or SERT are highlighted here.

  9. The discovery of novel human androgen receptor antagonist chemotypes using a combined pharmacophore screening procedure.

    Science.gov (United States)

    Voet, Arnout; Helsen, Christine; Zhang, Kam Y J; Claessens, Frank

    2013-04-01

    Unraveling the mechanisms involved in castration- and therapy-resistant prostate cancer has led to a renewed interest in androgen receptor (AR)-targeted therapeutics. Anti-androgens that block the activity of the AR therefore remain a valid therapeutic option. However, they must be more effective than, or display a distinct mechanism of action or binding mode from those of bicalutamide and hydroxyflutamide, which are currently in clinical use. For that reason, the second-generation anti-androgen MDV3100 was developed. MDV3100, however, shares its 4-cyano-3-(trifluoromethyl)phenyl group with bicalutamide and hydroxyflutamide required for binding to the AR. In this work, we used a combined strategy to find new antagonist structures distinct from the 4-cyano-3-(trifluoromethyl)phenyl group to avoid cross-resistance for these compounds and to find structures without agonist activity on mutant ARs (AR W741C and AR T877A). We found two novel chemotypes with AR-antagonistic activity (IC(50): 3-6 μM) by virtual screening and confirmed their biological activity in an androgen-responsive reporter assay. The design of our computational approach was validated by the observation of strongly decreased or absence of agonistic activity on the two mutant ARs. Further structural derivatization to optimize the potency of these compounds can render these chemotypes into very promising, alternative AR antagonists for prostate cancer therapy.

  10. Zatosetron, a potent, selective, and long-acting 5HT3 receptor antagonist: synthesis and structure-activity relationships.

    Science.gov (United States)

    Robertson, D W; Lacefield, W B; Bloomquist, W; Pfeifer, W; Simon, R L; Cohen, M L

    1992-01-24

    Antagonists of 5HT3 receptors are clinically effective in treating nausea and emesis associated with certain oncolytic drugs, including cisplatin. Moreover, these agents may be useful in pharmacological management of several central nervous system disorders, including anxiety, schizophrenia, dementia, and substance abuse. Our studies on aroyltropanamides led to the discovery that dihydrobenzofuranyl esters and amides are potent 5HT3 receptor antagonists. Simple benzoyl derivatives of tropine and 3 alpha-aminotropane possessed weak 5HT3 receptor antagonist activity, as judged by blockade of bradycardia produced by iv injection of serotonin (5HT) to anesthetized rats. Within this series, use of benzofuran-7-carboxamide as the aroyl moiety led to a substantial increase of 5HT3 receptor affinity. The optimal 5HT3 receptor antagonist identified via extensive SAR studies was endo-5-chloro-2,3-dihydro-2,2-dimethyl-N-(8-methyl-8-azabicyclo[3.2.1]oc t- 3-yl)-7-benzofurancarboxamide (Z)-2-butenedioate (zatosetron maleate). The 7-carbamyl regiochemistry, dimethyl substitution, chloro substituent, and endo stereochemistry were all crucial elements of the SAR. Zatosetron maleate was a potent antagonist of 5HT-induced bradycardia in rats (ED50 = 0.86 micrograms/kg i.v.). Low oral doses of zatosetron (30 micrograms/kg) produced long-lasting antagonism of 5HT3 receptors, as evidenced by blockade of 5HT-induced bradycardia for longer than 6 h in rats. Moreover, this compound did not produce hemodynamic effects after i.v. administration to rats, nor did it block carbamylcholine-induced bradycardia in doses that markedly blocked 5HT3 receptors. Thus, zatosetron is a potent, selective, orally effective 5HT3 receptor antagonist with a long duration of action in rats.

  11. BF-1--a novel selective 5-HT2B receptor antagonist blocking neurogenic dural plasma protein extravasation in guinea pigs.

    Science.gov (United States)

    Schmitz, Beate; Ullmer, Christoph; Segelcke, Daniel; Gwarek, Mirella; Zhu, Xin-Ran; Lübbert, Hermann

    2015-03-15

    Serotonin 5-HT2B receptor antagonists have been proposed as migraine prophylactic drugs, but previously available 5-HT2B receptor antagonists displayed multiple monoaminergic side effects and had to be withdrawn from the market. Here, we set out to identify a novel antagonist with high affinity and selectivity towards 5-HT2B receptors. To test the affinity of new compounds towards various receptors, we generated a broad series of cells functionally coupling human monoaminergic receptors to luciferase. Using the cell lines we revealed pimethixene (1-methyl-4-(9H-thioxanthen-9-ylidene)piperidine) as highly potent, albeit non-selective 5-HT2B receptor antagonist and optimized its chemical structure to create highly potent and selective 5-HT2B receptor antagonists. We selected the methoxythioxanthene BF-1 for further analysis. In comparison to pimethixene, it lacked high affinities to 5-HT1A, 5-HT2A, 5-HT2C, histamine H1, dopamine D1 and D2 as well as muscarinic M1 and M2 receptors. BF-1 was tested as potential migraine prophylactic drug by blocking meta-chlorophenylpiperazine, (mCPP) or BW723C86 (5-((thiophen-2-yl)methoxy)-α-methyltryptamine) induced neurogenic dural plasma protein extravasation in a guinea pig model that may resemble a migraine attack. BF-1 was significantly more potent in this assay compared to the well know non-selective 5-HT2B antagonists, methysergide ((6aR,9R)-N-[(2S)-1-Hydroxybutan-2-yl]-4,7-dimethyl-6,6a,8,9-tetrahydroindolo[4,3-fg]quinoline-9-carboxamide) or pizotifen (4-(1-methyl-4-piperidylidine)-9,10-dihydro-4H-benzo-[4,5]cyclohepta[1,2]-thiophene). Therefore, we propose BF-1 as a new compound that may be developed for prophylactic migraine treatment without the typical monoaminergic side effects.

  12. Effects of the 5-HT(6) receptor antagonist Ro 04-6790 on learning consolidation.

    Science.gov (United States)

    Meneses, A

    2001-01-08

    The 5-HT(6) receptor antagonist Ro-04-6790 or 8-OH-DPAT injection improved learning consolidation on an autoshaping task, while mCPP, scopolamine and dizocilpine decreased the performance. The effect induced by scopolamine, but not that induced by mCPP, was reversed completely by Ro-04-6790, while dizocilpine effect was antagonized partially. Nevertheless, ritanserin or WAY 100635, but not Ro 04-6790, antagonized the 8-OH-DPAT facilitatory effects on learning consolidation. As WAY 100635 did not modify the Ro 04-6790 facilitatory effect, hence 5-HT(1A), and/or 5-HT(7), but not 5-HT(6), receptors might mediate the 8-OH-DPAT facilitatory effect on learning consolidation. Since, the Ro 04-6790 facilitatory effect was unaffected by 5-HT(1A), 5-HT(2A)/(2B)/(2C), 5-HT(3) or 5-HT(4) receptor blockade, thereby, the facilitatory effect induced by Ro 04-6790 involved specifically 5-HT(6) receptors. Indeed, the present data provide further support to the notion that, 5-HT(6) receptors play a significant part in the learning consolidation under normal and dysfunctional memory conditions.

  13. Oxime Ethers of (E)-11-Isonitrosostrychnine as Highly Potent Glycine Receptor Antagonists.

    Science.gov (United States)

    Mohsen, Amal M Y; Mandour, Yasmine M; Sarukhanyan, Edita; Breitinger, Ulrike; Villmann, Carmen; Banoub, Maha M; Breitinger, Hans-Georg; Dandekar, Thomas; Holzgrabe, Ulrike; Sotriffer, Christoph; Jensen, Anders A; Zlotos, Darius P

    2016-12-23

    A series of (E)-11-isonitrosostrychnine oxime ethers, 2-aminostrychnine, (strychnine-2-yl)propionamide, 18-oxostrychnine, and N-propylstrychnine bromide were synthesized and evaluated pharmacologically at human α1 and α1β glycine receptors in a functional fluorescence-based and a whole-cell patch-clamp assay and in [(3)H]strychnine binding studies. 2-Aminostrychnine and the methyl, allyl, and propargyl oxime ethers were the most potent α1 and α1β antagonists in the series, displaying IC50 values similar to those of strychnine at the two receptors. Docking experiments to the strychnine binding site of the crystal structure of the α3 glycine receptor indicated the same orientation of the strychnine core for all analogues. For the most potent oxime ethers, the ether substituent was accommodated in a lipophilic receptor binding pocket. The findings identify the oxime hydroxy group as a suitable attachment point for linking two strychnine pharmacophores by a polymethylene spacer and are, therefore, important for the design of bivalent ligands targeting glycine receptors.

  14. Preclinical pharmacology and pharmacokinetics of AZD3783, a selective 5-hydroxytryptamine 1B receptor antagonist.

    Science.gov (United States)

    Zhang, Minli; Zhou, Diansong; Wang, Yi; Maier, Donna L; Widzowski, Daniel V; Sobotka-Briner, Cynthia D; Brockel, Becky J; Potts, William M; Shenvi, Ashok B; Bernstein, Peter R; Pierson, M Edward

    2011-11-01

    The preclinical pharmacology and pharmacokinetic properties of (2R)-6-methoxy-8-(4-methylpiperazin-1-yl)-N-(4-morpholin-4-ylphenyl)chromane-2-carboxamide (AZD3783), a potent 5-hydroxytryptamine 1B (5-HT(1B)) receptor antagonist, were characterized as part of translational pharmacokinetic/pharmacodynamic hypothesis testing in human clinical trials. The affinity of AZD3783 to the 5-HT(1B) receptor was measured in vitro by using membrane preparations containing recombinant human or guinea pig 5-HT(1B) receptors and in native guinea pig brain tissue. In vivo antagonist potency of AZD3783 for the 5HT(1B) receptor was investigated by measuring the blockade of 5-HT(1B) agonist-induced guinea pig hypothermia. The anxiolytic-like potency was assessed using the suppression of separation-induced vocalization in guinea pig pups. The affinity of AZD3783 for human and guinea pig 5-HT(1B) receptor (K(i), 12.5 and 11.1 nM, respectively) was similar to unbound plasma EC(50) values for guinea pig receptor occupancy (11 nM) and reduction of agonist-induced hypothermia (18 nM) in guinea pig. Active doses of AZD3783 in the hypothermia assay were similar to doses that reduced separation-induced vocalization in guinea pig pups. AZD3783 demonstrated favorable pharmacokinetic properties. The predicted pharmacokinetic parameters (total plasma clearance, 6.5 ml/min/kg; steady-state volume of distribution, 6.4 l/kg) were within 2-fold of the values observed in healthy male volunteers after a single 20-mg oral dose. This investigation presents a direct link between AZD3783 in vitro affinity and in vivo receptor occupancy to preclinical disease model efficacy. Together with predicted human pharmacokinetic properties, we have provided a model for the quantitative translational pharmacology of AZD3783 that increases confidence in the optimal human receptor occupancy required for antidepressant and anxiolytic effects in patients.

  15. Screening and identification of receptor antagonist for shiga toxin from random peptides displayed on filamentous bacteriophages

    Institute of Scientific and Technical Information of China (English)

    韩照中; 苏国富; 黄翠芬

    1999-01-01

    The bacteriophage clones which can bind with shiga toxin B subunit (StxB) and inhibit cytotoxicity of shiga toxin were obtained by using antibody capturing method from a 15-mer random peptide library displayed on the surface of bacteriophage fd. Among them, one peptide encoded by the random DNA region of a selected bacteriophage (A12) was synthesized and tested in vitro and in vivo, where the peptide competed with the receptor of shiga toxin to bind StxB, and inhibited the cytotoxicity and enterotoxicity of shiga toxin. The peptide can also block other apparently unrelated StxB binding bacteriophage (A3), which suggests that there are overlapping StxB interaction sites for those ligands with different sequences. The results provide a demonstration of bacteriophage display to screen peptide ligands for a small and/or unable biotinylated molecule by antibodies-capturing strategy, and take the lead for the development of receptor antagonists for shiga toxin.

  16. Characterization of SB-269970-A, a selective 5-HT7 receptor antagonist

    OpenAIRE

    Hagan, Jim J.; Price, Gary W; Jeffrey, Phillip; Deeks, Nigel J; Stean, Tania; Piper, David; Smith, Martin I; Upton, Neil; Medhurst, Andrew D; Middlemiss, Derek N; Riley, Graham J; Lovell, Peter J; Bromidge, Steven M; Thomas, David R.

    2000-01-01

    The novel 5-HT7 receptor antagonist, SB-269970-A, potently displaced [3H]-5-CT from human 5-HT7(a) (pKi 8.9±0.1) and 5-HT7 receptors in guinea-pig cortex (pKi 8.3±0.2).5-CT stimulated adenylyl cyclase activity in 5-HT7(a)/HEK293 membranes (pEC50 7.5±0.1) and SB-269970-A (0.03–1 μM) inhibited the 5-CT concentration-response with no significant alteration in the maximal response. The pA2 (8.5±0.2) for SB-269970-A agreed well with the pKi determined from [3H]-5-CT binding studies.5-CT-stimulated...

  17. Recent advances in the development of dopamine D3 receptor antagonists: a medicinal chemistry perspective.

    Science.gov (United States)

    Micheli, Fabrizio

    2011-07-04

    Dopamine (DA) D(3) receptor antagonism might play a significant role in different therapeutic areas. A high number of preclinical studies on DA D(3) receptor antagonists have shown efficacy in animal models of Parkinson's disease, schizophrenia and drug dependence. This Review covers the activities of medicinal chemists in this field over the last ten years towards the identification of truly selective compounds. Both primary and patent literature is reviewed here. Since the original discoveries, a clear trend towards the optimization of the developability properties of the new scaffold has clearly emerged with time, from both academic and industrial researchers. Examples of advanced leads from academia and industry are described. The latest potential therapeutic applications are reported too.

  18. Estrogen receptor agonists/antagonists in breast cancer therapy: A critical review.

    Science.gov (United States)

    Jameera Begam, A; Jubie, S; Nanjan, M J

    2017-04-01

    Estrogens display intriguing tissue selective action that is of great biomedical importance in the development of optimal therapeutics for the prevention and treatment of breast cancer. There are also strong evidences to show that both endogenous and exogenous estrogens are involved in the pathogenesis of breast cancer. Tamoxifen has been the only drug of choice for more than 30years to treat patients with estrogen related (ER) positive breast tumors. There is a need therefore, for identifying newer, potential and novel candidates for breast cancer. Keeping this in view, the present review focuses on selective estrogen receptor modulators and estrogen antagonists such as sulfatase and aromatase inhibitors involved in breast cancer therapy. A succinct and critical overview of the structure of estrogen receptors, their signaling and involvement in breast carcinogenesis are herein described. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Characterization of SB-269970-A, a selective 5-HT7 receptor antagonist

    OpenAIRE

    Hagan, Jim J; Price, Gary W; Jeffrey, Phillip; Deeks, Nigel J; Stean, Tania; Piper, David; Smith, Martin I.; Upton, Neil; Medhurst, Andrew D.; Middlemiss, Derek N; Riley, Graham J; Lovell, Peter J; Bromidge, Steven M; Thomas, David R.

    2000-01-01

    The novel 5-HT7 receptor antagonist, SB-269970-A, potently displaced [3H]-5-CT from human 5-HT7(a) (pKi 8.9±0.1) and 5-HT7 receptors in guinea-pig cortex (pKi 8.3±0.2).5-CT stimulated adenylyl cyclase activity in 5-HT7(a)/HEK293 membranes (pEC50 7.5±0.1) and SB-269970-A (0.03–1 μM) inhibited the 5-CT concentration-response with no significant alteration in the maximal response. The pA2 (8.5±0.2) for SB-269970-A agreed well with the pKi determined from [3H]-5-CT binding studies.5-CT-stimulated...

  20. De novo analysis of receptor binding affinity data of xanthine adenosine receptor antagonists.

    Science.gov (United States)

    Dalpiaz, A; Gardenghi, A; Borea, P A

    1995-03-01

    The receptor binding affinity data to adenosine A1 and A2 receptors of a wide series of xanthine derivatives have been analyzed by means of the Free-Wilson model. The analysis of the individual group contribution shows, for both A1 and A2 receptors, the primary importance of the presence of bulky substituents at position 8 for an optimum receptor binding. Moreover, considering the different aij contributions of bulky substituents at position 8 for affinity to A1 with respect to A2 receptors, this position appears to be the most important for the synthesis of highly A1 selective xanthine derivatives. Moreover the analysis of group contributions for other substitution positions of the xanthine moiety allows to state that suitable substitutions at positions 3 and 7 could confer some degree of A2 selectivity.

  1. Antarlides: A New Type of Androgen Receptor (AR) Antagonist that Overcomes Resistance to AR-Targeted Therapy.

    Science.gov (United States)

    Saito, Shun; Fujimaki, Takahiro; Panbangred, Watanalai; Igarashi, Yasuhiro; Imoto, Masaya

    2016-02-18

    Prostate cancer is treated with androgen receptor (AR) antagonists but most patients experience disease progression after long-term treatment with these compounds. Therefore, new AR antagonists are required for patient follow-up treatment. In the course of screening for a new AR antagonist, we isolated the novel compounds antarlides A-E (1-5) from Streptomyces sp. BB47. Antarlides are mutually isomeric with respect to the double bond and have a 22-membered-ring macrocyclic structure. The full stereostructure of 1 was established by chemical modifications, including methanolysis, the Trost method, acetonide formation, and the PGME method. 1-5 inhibited the binding of androgen to ARs in vitro. In addition, 2 inhibited the transcriptional activity of not only wild-type AR but also mutant ARs, which are seen in patients with acquired resistance to clinically used AR antagonists. Therefore, antarlides are a potent new generation of AR antagonists that overcome resistance.

  2. Influence of different histamine receptor agonists and antagonists on apomorphine-induced licking behavior in rat.

    Science.gov (United States)

    Farzin, D; Attarzadeh, M

    2000-09-15

    The effects of different histamine receptor agonists and antagonists on apomorphine-induced licking behavior in rats were investigated. Subcutaneous (s.c.) injection of various doses of apomorphine (0. 125-1.25 mg/kg) induced licking. The licking response was counted by direct observation and recorded for a 75-min period. Intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) injection of the histamine H(1) or H(2) receptor agonist, HTMT (6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide) (50 and 100 microg per rat), or dimaprit (10 and 15 mg/kg, i.p.), respectively, potentiated apomorphine-induced licking, while the histamine H(3) receptor agonist, imetit (5 and 10 mg/kg, i.p.), reduced the licking response induced by apomorphine. Pretreatment with various histamine receptor antagonists, dexchlorpheniramine (30 and 40 mg/kg, i.p.), diphenhydramine (20, 30 and 40 mg/kg, i.p.), famotidine (30 and 40 mg/kg, s.c.) and ranitidine (20, 30 and 40 mg/kg), reduced apomorphine-induced licking, while thioperamide (5 and 10 mg/kg, i.p.) potentiated the apomorphine effect. The effects of HTMT and dimaprit were blocked by dexchlorpheniramine (20 mg/kg, i.p.) and famotidine (20 mg/kg, s.c.), respectively. The inhibitory effect elicited by imetit on apomorphine-induced licking behavior was also abolished in animals treated with thioperamide (2.5 mg/kg, i.p.). The results suggest that histaminergic mechanisms may be involved in the modulation of apomorphine-induced licking behavior.

  3. Direct demonstration of D1 dopamine receptors in the bovine parathyroid gland using the D1 selective antagonist (/sup 125/I)-SCH 23982

    Energy Technology Data Exchange (ETDEWEB)

    Monsma, F.J. Jr.; Sibley, D.R.

    1989-01-01

    The presence of D1 dopamine receptors in the parathyroid gland has been proposed based on the demonstration of dopaminergic regulation of adenylate cyclase activity and parathyroid hormone release in dispersed bovine parathyroid cells. Using a radioiodinated D1 selective antagonist (125I)-SCH 23982, we have now directly labeled and characterized the D1 dopamine receptors in bovine parathyroid gland membranes. (125I)-SCH 23982 binds in a saturable manner with high affinity and low nonspecific binding to membranes prepared from bovine parathyroid glands. D1 dopamine receptors are present in this preparation at a concentration of approximately 130 fMoles/mg protein and (125I)-SCH 23982 binding increases with increasing protein concentration in a linear fashion. Determination of the Kd using the association (k1) and dissociation (k-1) rate constants revealed good agreement with the Kd determined by saturation analysis (390 pM vs. 682 pM, respectively). Inhibition of 0.3 nM (125I)-SCH 23982 binding by a series of dopaminergic antagonists verified the D1 nature of this binding site, exhibiting appropriate affinities and rank order of potency. The competition curves of all antagonists exhibited Hill coefficients that were not significantly different from 1. Inhibition of (125I)-SCH 23982 binding by dopamine and other dopaminergic agonists revealed the presence of high and low affinity agonist binding sites. Addition of 200 microM GppNHp effected a complete conversion of high affinity dopamine binding sites to a homogeneous population of low affinity dopamine sites. The D1 receptors identified in the parathyroid gland with (125I)-SCH 23982 appear to be pharmacologically identical with those previously characterized in the central nervous system.

  4. Receptor-mediated binding and uptake of GnRH agonist and antagonist by pituitary cells

    Energy Technology Data Exchange (ETDEWEB)

    Jennes, L.; Stumpf, W.E.; Conn, P.M.

    1984-01-01

    The intracellular pathway of an enzyme resistant GnRH agonist (D- Lys6 -GnRH) conjugated to ferritin or to colloidal gold was followed in cultured pituitary cells. After an initial uniform distribution over the cell surface of gonadotropes, the electrondense marker was internalized, either individually or in small groups. After longer incubation times, the marker appeared in the lysosomal compartment and the Golgi apparatus, where it could be found in the vesicular as well as cisternal portion. In addition, the receptor-mediated endocytosis of the GnRH antagonist D-p-Glu1-D-Phe2-D-Trp3-D- Lys6 -GnRH was studied by light and electron microscopic autoradiography after 30 and 60 min of incubation to ensure uptake. At both time points, in in vitro as well as in vivo studies, silver grains were localized over cytoplasmic organelles of castration cells, including dilated endoplasmic reticulum, lysosomes, and clear vesicles. No consistent association with cell nuclei, mitochondria, or secretory vesicles could be observed. The results suggest that both agonist and antagonist are binding selectively to the plasma membrane of gonadotropes and subsequently are taken up via receptor-mediated endocytosis for degradation or possible action on synthetic processes.

  5. Cysteinyl Leukotriene Receptor-1 Antagonists as Modulators of Innate Immune Cell Function

    Directory of Open Access Journals (Sweden)

    A. J. Theron

    2014-01-01

    Full Text Available Cysteinyl leukotrienes (cysLTs are produced predominantly by cells of the innate immune system, especially basophils, eosinophils, mast cells, and monocytes/macrophages. Notwithstanding potent bronchoconstrictor activity, cysLTs are also proinflammatory consequent to their autocrine and paracrine interactions with G-protein-coupled receptors expressed not only on the aforementioned cell types, but also on Th2 lymphocytes, as well as structural cells, and to a lesser extent neutrophils and CD8+ cells. Recognition of the involvement of cysLTs in the immunopathogenesis of various types of acute and chronic inflammatory disorders, especially bronchial asthma, prompted the development of selective cysLT receptor-1 (cysLTR1 antagonists, specifically montelukast, pranlukast, and zafirlukast. More recently these agents have also been reported to possess secondary anti-inflammatory activities, distinct from cysLTR1 antagonism, which appear to be particularly effective in targeting neutrophils and monocytes/macrophages. Underlying mechanisms include interference with cyclic nucleotide phosphodiesterases, 5′-lipoxygenase, and the proinflammatory transcription factor, nuclear factor kappa B. These and other secondary anti-inflammatory mechanisms of the commonly used cysLTR1 antagonists are the major focus of the current review, which also includes a comparison of the anti-inflammatory effects of montelukast, pranlukast, and zafirlukast on human neutrophils in vitro, as well as an overview of both the current clinical applications of these agents and potential future applications based on preclinical and early clinical studies.

  6. Randomized controlled trial of the CGRP receptor antagonist telcagepant for migraine prevention

    DEFF Research Database (Denmark)

    Ho, Tony W; Connor, Kathryn M; Zhang, Ying

    2014-01-01

    OBJECTIVE: To evaluate whether the calcitonin gene-related peptide (CGRP) receptor antagonist telcagepant might be effective for migraine prevention. METHODS: In this randomized, double-blind, placebo-controlled, multicenter trial (ClinicalTrials.gov NCT00797667), patients experiencing 3-14 migra......OBJECTIVE: To evaluate whether the calcitonin gene-related peptide (CGRP) receptor antagonist telcagepant might be effective for migraine prevention. METHODS: In this randomized, double-blind, placebo-controlled, multicenter trial (ClinicalTrials.gov NCT00797667), patients experiencing 3......-14 migraine days during a 4-week baseline were randomized to telcagepant 140 mg, telcagepant 280 mg, or placebo twice daily for 12 weeks. Efficacy was assessed by mean monthly headache days and migraine/probable migraine days (headache plus ≥ 1 associated symptom). RESULTS: The trial was terminated following...... a recommendation from the Safety Monitoring Board due to hepatotoxicity concerns. At termination, the planned 660 patients had been randomized, 656 had been treated with ≥ 1 dose of study medication, and 14 had completed the trial. The mean treatment duration was 48-50 days. Thirteen patients, all...

  7. Selective Glucocorticoid Receptor (GR-II Antagonist Reduces Body Weight Gain in Mice

    Directory of Open Access Journals (Sweden)

    Tomoko Asagami

    2011-01-01

    Full Text Available Previous research has shown that mifepristone can prevent and reverse weight gain in animals and human subjects taking antipsychotic medications. This proof-of-concept study tested whether a more potent and selective glucocorticoid receptor antagonist could block dietary-induced weight gain and increase insulin sensitivity in mice. Ten-week-old, male, C57BL/6J mice were fed a diet containing 60% fat calories and water supplemented with 11% sucrose for 4 weeks. Groups (=8 received one of the following: CORT 108297 (80 mg/kg QD, CORT 108297 (40 mg/kg BID, mifepristone (30 mg/kg BID, rosiglitazone (10 mg/kg QD, or vehicle. Compared to mice receiving a high-fat, high-sugar diet plus vehicle, mice receiving a high-fat, high-sugar diet plus either mifepristone or CORT 108297 gained significantly less weight. At the end of the four week treatment period, mice receiving CORT 108297 40 mg/kg BID or CORT 108297 80 mg/kg QD also had significantly lower steady plasma glucose than mice receiving vehicle. However, steady state plasma glucose after treatment was not highly correlated with reduced weight gain, suggesting that the effect of the glucocorticoid receptor antagonist on insulin sensitivity may be independent of its mitigating effect on weight gain.

  8. Retro-inverso Urokinase Receptor Antagonists for the Treatment of Metastatic Sarcomas.

    Science.gov (United States)

    Carriero, Maria Vincenza; Bifulco, Katia; Ingangi, Vincenzo; Costantini, Susan; Botti, Giovanni; Ragone, Concetta; Minopoli, Michele; Motti, Maria Letizia; Rea, Domenica; Scognamiglio, Giosuè; Botti, Gerardo; Arra, Claudio; Ciliberto, Gennaro; Pessi, Antonello

    2017-05-02

    The development of metastases is a multistep process that requires the activation of physiological and biochemical processes that govern migration, invasion and entry of metastatic cells into blood vessels. The urokinase receptor (uPAR) promotes cell migration by interacting with the Formyl Peptide Receptors (FPRs). Since both uPAR and FPR1 are involved in tumor progression, the uPAR-FPR1 interaction is an attractive therapeutic target. We previously described peptide antagonists of the uPAR-FPR1 interaction that inhibited cell migration and angiogenesis. To develop enzyme-resistant analogues, we applied here the Retro-Inverso (RI) approach, whereby the topology of the side chains is maintained by inverting the sequence of the peptide and the chirality of all residues. Molecular dynamics suggests that peptide RI-3 adopts the turn structure typical of uPAR-FPR1 antagonists. Accordingly, RI-3 is a nanomolar competitor of N-formyl-Met-Leu-Phe for binding to FPR1 and inhibits migration, invasion, trans-endothelial migration of sarcoma cells and VEGF-triggered endothelial tube formation. When sarcoma cells were subcutaneously injected in nude mice, tumor size, intra-tumoral microvessel density, circulating tumor cells and pulmonary metastases were significantly reduced in animals treated daily with 6 mg/Kg RI-3 as compared to animals treated with vehicle only. Thus, RI-3 represents a promising lead for anti-metastatic drugs.

  9. A new sensitive flow-injection chemiluminescence method for the determination of H(2)-receptor antagonists.

    Science.gov (United States)

    Tang, Yu-Hai; Wang, Nan-Nan; Xiong, Xun-Yu; Xiong, Feng-Mei; Sun, Si-Juan

    2007-01-01

    Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K(3)Fe(CN)(6)]-rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow-injection chemiluminescence (FI-CL) method has been developed, validated and applied for the determination of three kinds of H(2)-receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 x 10(-9)-7.0 x 10(-5) g/ml for CIMT, 1.0 x 10(-9)-5.0 x 10(-5) g/mL for RANT hydrochloride and 5.0 x 10(-9)-7.0 x 10(-5) g/mL for FAMT. During 11 repeated measurements of 1.0 x 10(-6) g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 x 10(-10) g/mL for CIMT, 8.69 x 10(-10) g/mL for RANT hydrochloride and 2.35 x 10(-9) g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H(2)-receptor antagonists in pharmaceuticals.

  10. Pegvisomant: a growth hormone receptor antagonist used in the treatment of acromegaly.

    Science.gov (United States)

    Tritos, Nicholas A; Biller, Beverly M K

    2017-02-01

    To review published data on pegvisomant and its therapeutic role in acromegaly. Electronic searches of the published literature were conducted using the keywords: acromegaly, growth hormone (GH) receptor (antagonist), pegvisomant, therapy. Relevant articles (n = 141) were retrieved and considered for inclusion in this manuscript. Pegvisomant is a genetically engineered, recombinant growth hormone receptor antagonist, which is effective in normalizing serum insulin-like growth factor 1 (IGF-1) levels in the majority of patients with acromegaly and ameliorating symptoms and signs associated with GH excess. Pegvisomant does not have direct antiproliferative effects on the underlying somatotroph pituitary adenoma, which is the etiology of GH excess in the vast majority of patients with acromegaly. Therefore, patients receiving pegvisomant monotherapy require regular pituitary imaging in order to monitor for possible increase in tumor size. Adverse events in patients on pegvisomant therapy include skin rashes, lipohypertrophy at injection sites, and idiosyncratic liver toxicity (generally asymptomatic transaminitis that is reversible upon drug discontinuation), thus necessitating regular patient monitoring. Pegvisomant is an effective therapeutic agent in patients with acromegaly who are not in remission after undergoing pituitary surgery. It mitigates excess GH action, as demonstrated by IGF-1 normalization, but has no direct effects on pituitary tumors causing acromegaly. Regular surveillance for possible tumor growth and adverse effects (hepatotoxicity, skin manifestations) is warranted.

  11. Interleukin-1 receptor antagonist gene polymorphism and mortality in patients with severe sepsis

    Science.gov (United States)

    ARNALICH, F; LÓPEZ-MADERUELO, D; CODOCEO, R; LOPEZ, J; SOLIS-GARRIDO, L M; CAPISCOL, C; FERNANDEZ-CAPITÁN, C; MADERO, R; MONTIEL, C

    2002-01-01

    This study aims to determine the influence of the polymorphism within the intron 2 of the interleukin-1 receptor antagonist gene (IL-1RN*) on the outcome of severe sepsis, and to assess its functional significance by correlating this polymorphism with the total production of interleukin-1 receptor antagonist (IL-1Ra) protein determined in stimulated peripheral blood mononuclear cells (PBMC). A group of 78 patients with severe sepsis (51 survivors and 27 nonsurvivors) was compared with a healthy control group of 130 blood donors, and 56 patients with uncomplicated pneumonia. We found a significant association between IL-1RN* polymorphism and survival. Thus, after adjusting for age and APACHE II score, multiple logistic regression analysis showed that patients homozygotes for the allele *2 had a 6·47-fold increased risk of death (95% CI 1·01–41·47, P = 0·04). Besides, compared with patients homozygous or heterozygous for the allele *1, IL-1RN*2 homozygotes produced significantly lower levels of IL-1Ra from their PBMC. Our results suggest that insufficient production of this cytokine might contribute, among other factors, to the higher mortality rate found in severe sepsis patients with the IL-1RN*2 homozygous genotype. PMID:11876758

  12. Discriminating agonist and antagonist ligands of the nuclear receptors using 3D-pharmacophores.

    Science.gov (United States)

    Lagarde, Nathalie; Delahaye, Solenne; Zagury, Jean-François; Montes, Matthieu

    2016-01-01

    Nuclear receptors (NRs) constitute an important class of therapeutic targets. We evaluated the performance of 3D structure-based and ligand-based pharmacophore models in predicting the pharmacological profile of NRs ligands using the NRLiSt BDB database. We could generate selective pharmacophores for agonist and antagonist ligands and we found that the best performances were obtained by combining the structure-based and the ligand-based approaches. The combination of pharmacophores that were generated allowed to cover most of the chemical space of the NRLiSt BDB datasets. By screening the whole NRLiSt BDB on our 3D pharmacophores, we demonstrated their selectivity towards their dedicated NRs ligands. The 3D pharmacophores herein presented can thus be used as a predictor of the pharmacological activity of NRs ligands.Graphical AbstractUsing a combination of structure-based and ligand-based pharmacophores, agonist and antagonist ligands of the Nuclear Receptors included in the NRLiSt BDB database could be separated.

  13. Drug therapy of apparent treatment-resistant hypertension: focus on mineralocorticoid receptor antagonists.

    Science.gov (United States)

    Glicklich, Daniel; Frishman, William H

    2015-04-01

    Apparent treatment-resistant hypertension (aTRH) is defined as blood pressure (BP) >140/90 mmHg despite three different antihypertensive drugs including a diuretic. aTRH is associated with an increased risk of cardiovascular events, including stroke, chronic renal failure, myocardial infarction, congestive heart failure, aortic aneurysm, atrial fibrillation, and sudden death. Preliminary studies of renal nerve ablation as a therapy to control aTRH were encouraging. However, these results were not confirmed by the Symplicity 3 trial. Therefore, attention has refocused on drug therapy. Secondary forms of hypertension and associated conditions such as obesity, sleep apnea, and primary aldosteronism are common in patients with aTRH. The pivotal role of aldosterone in the pathogenesis of aTRH in many cases is well recognized. For patients with aTRH, the Joint National Committee-8, the European Society of Hypertension, and a recent consensus conference recommend that a diuretic, ACE inhibitor, or angiotensin receptor blocker and calcium channel blocker combination be used to maximally tolerated doses before starting a 'fourth-line' drug such as a mineralocorticoid receptor (MR) antagonist. Although the best fourth-line drug for aTRH has not been extensively investigated, a number of studies summarized here show that an MR antagonist is effective in reducing BP when added to the standard multi-drug regimen.

  14. Evaluation of the abuse potential of AM281, a new synthetic cannabinoid CB1 receptor antagonist.

    Science.gov (United States)

    Botanas, Chrislean Jun; de la Peña, June Bryan; Dela Pena, Irene Joy; Tampus, Reinholdgher; Kim, Hee Jin; Yoon, Seong Shoon; Seo, Joung-Wook; Jeong, Eun Ju; Cheong, Jae Hoon

    2015-11-01

    AM281 (1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide) is a new synthetic cannabinoid CB1 receptor antagonist. Similar to other cannabinoid antagonists, AM281 has been suggested to have therapeutic indications. However, recent reports have suggested that cannabinoid CB1 receptor antagonists may share similar behavioral effects with other drugs of abuse such as cocaine and amphetamine. These reports cast doubts on the safety profile of AM281. Thus, in the present study we evaluated the abuse potential (rewarding and reinforcing effects) of AM281 through two of the most widely used animal models for assessing the abuse potential of drugs: the conditioned place preference (CPP) and self-administration (SA) tests. Experiments were performed in Sprague-Dawley rats in various dosages [CPP (0.1, 0.5 or 2.5mg/kg), SA (0.005, 0.025 or 0.1mg/kg/infusion)]. We also delved into the consequences of repeated drug exposure on the subsequent response to the drug. Thus, parallel experiments were carried out in rats pretreated with AM281 for 7 or 14 days. Our findings indicated that AM281, at any dose, did not induce CPP and SA in drug-naïve rats. Interestingly, significant CPP (0.5mg/kg of AM281), but not SA, was observed in 14 days pretreated rats. These observations suggest that AM281 per se has no or minimal rewarding and reinforcing properties, but alterations in neuronal functions and behavior due to repeated AM281 exposure may contribute in part to the abuse potential of this drug. In view of this finding, we advocate the careful use, monitoring, and dispensation of AM281.

  15. Analgesic effects of novel lysophosphatidic acid receptor 5 antagonist AS2717638 in rodents.

    Science.gov (United States)

    Murai, Nobuhito; Hiyama, Hideki; Kiso, Tetsuo; Sekizawa, Toshihiro; Watabiki, Tomonari; Oka, Hiromasa; Aoki, Toshiaki

    2017-08-30

    Lysophosphatidic acid (LPA) is a bioactive lipid that acts via at least six G protein-coupled receptors, LPA receptors 1-6 (LPA1-6), for various physiological functions. We examined (1) whether LPA5 is involved in pain signaling in the spinal cord; and (2) the pharmacological effects of a novel LPA5 antagonist on intrathecal prostaglandin (PG)- and (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced allodynia, and neuropathic and inflammatory pain in rodents. Intrathecal injection of a selective LPA5 agonist, geranylgeranyl diphosphate, and a non-selective agonist, LPA, induced allodynia in wild type, but not in LPA5 knockout mice. These novel results suggest that LPA5 is important for pain signal transmission in the spinal cord. AS2717638 (6,7-dimethoxy-2-(5-methyl-1,2-benzoxazol-3-yl)-4-(piperidin-1-ylcarbonyl)isoquinolin-1(2H)-one) bound to the LPA-binding site on LPA5 and selectively inhibited LPA-induced cyclic adenosine monophosphate accumulation in human LPA5-but not LPA1-, 2-, or 3-expressing cells. Further, oral administration of AS2717638 inhibited LPA5 agonist-induced allodynia in mice. AS2717638 also significantly improved PGE2-, PGF2α-, and AMPA-induced allodynia, while both pregabalin and duloxetine alleviated only PGE2-induced allodynia in mice. Similarly, AS2717638 significantly ameliorated static mechanical allodynia and thermal hyperalgesia in rat models of chronic constriction injury (CCI)-induced neuropathic pain. AS2717638 also showed analgesic effects in a rat model of inflammatory pain. These findings suggest that LPA5 antagonists elicit broad analgesic effects against both neuropathic and inflammatory pain. Accordingly, pharmacological LPA5 antagonists are attractive development candidates for potential novel pain therapies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. A Pharmacokinetic/Pharmacodynamic Study of the Glucocorticoid Receptor Antagonist Mifepristone Combined with Enzalutamide in Castrate-Resistant Prostate Cancer

    Science.gov (United States)

    2014-12-01

    combination of mifepristone and enzalutamide has been well tolerated with no dose limiting toxicities . The current cohort has dose- escalated the...Pharmacodynamic Study of the Glucocorticoid Receptor Antagonist Mifepristone Combined with Enzalutamide in Castrate-Resistant Prostate Cancer...Antagonist Mifepristone Combined with Enzalutamide in Castrate-Resistant Prostate Cancer 5b. GRANT NUMBER W81XWH-14-1-0021 5c. PROGRAM ELEMENT

  17. The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine

    Directory of Open Access Journals (Sweden)

    Farajian Mashhadi

    2014-03-01

    Full Text Available Background The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS in different regions of the rat intestine. Materials and Methods Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist and granisetron up to 10.0 µM, GR113808 (a 5-HT4 receptor antagonist, methysergide and ritanserin up to 1.0 µM, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 µM (a 5-HT6 receptor antagonist there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 µM (5-HT7 receptor antagonist induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 µM did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions.

  18. Receptors and Channels Targeted by Synthetic Cannabinoid Receptor Agonists and Antagonists

    OpenAIRE

    Pertwee, R. G.

    2010-01-01

    It is widely accepted that non-endogenous compounds that target CB1 and/or CB2 receptors possess therapeutic potential for the clinical management of an ever growing number of disorders. Just a few of these disorders are already treated with Δ9-tetrahydrocannabinol or nabilone, both CB1/CB2 receptor agonists, and there is now considerable interest in expanding the clinical applications of such agonists and also in exploiting CB2-selective agonists, peripherally restricted CB1/CB2 receptor ago...

  19. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs*

    Science.gov (United States)

    Pediani, John D.; Ward, Richard J.; Godin, Antoine G.; Marsango, Sara

    2016-01-01

    Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm−2 human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior. PMID:27080256

  20. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs.

    Science.gov (United States)

    Pediani, John D; Ward, Richard J; Godin, Antoine G; Marsango, Sara; Milligan, Graeme

    2016-06-17

    Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm(-2) human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Novel benzamide-based histamine h3 receptor antagonists: the identification of two candidates for clinical development.

    Science.gov (United States)

    Letavic, Michael A; Aluisio, Leah; Apodaca, Richard; Bajpai, Manoj; Barbier, Ann J; Bonneville, Anne; Bonaventure, Pascal; Carruthers, Nicholas I; Dugovic, Christine; Fraser, Ian C; Kramer, Michelle L; Lord, Brian; Lovenberg, Timothy W; Li, Lilian Y; Ly, Kiev S; Mcallister, Heather; Mani, Neelakandha S; Morton, Kirsten L; Ndifor, Anthony; Nepomuceno, S Diane; Pandit, Chennagiri R; Sands, Steven B; Shah, Chandra R; Shelton, Jonathan E; Snook, Sandra S; Swanson, Devin M; Xiao, Wei

    2015-04-09

    The preclinical characterization of novel phenyl(piperazin-1-yl)methanones that are histamine H3 receptor antagonists is described. The compounds described are high affinity histamine H3 antagonists. Optimization of the physical properties of these histamine H3 antagonists led to the discovery of several promising lead compounds, and extensive preclinical profiling aided in the identification of compounds with optimal duration of action for wake promoting activity. This led to the discovery of two development candidates for Phase I and Phase II clinical trials.

  2. Combined histamine H1/H2 receptor antagonists: part I. Pharmacological hybrids with pheniramine- and roxatidine-like substructures.

    Science.gov (United States)

    Schulze, F R; Buschauer, A; Schunack, W

    1998-07-01

    A series of hybrid compounds combining the pharmacophores of both pheniramine-type histamine H1 receptor antagonists and roxatidine-type H2 receptor antagonists have been synthesized and tested for histamine antagonism at the isolated ileum (H1) and the spontaneously beating right atrium (H2) of the guinea pig. The 'polar group' of the H2 antagonist moiety (cyanoguanidine, nitroethenediamine or urea) and the side chain amino group of the H1 antagonist portion have been linked by a polymethylene spacer or by a piperazine system. The incorporation of a flexible spacer (2-7 methylene groups) resulted in H1 antagonists achieving up to 2.4 times the activity of pheniramine. Depending on the nature of the polar group the highest H2 antagonist potency resides in compounds with spacers ?2 methylene groups. Nitroethenediamine 24c with a seven-membered chain and a chlorpheniramine substructure proved to be approximately equipotent with pheniramine at the H1 and with ranitidine at the H2 receptor (pKB values 7.82 and 7.1, respectively).

  3. Effects of the nonpeptide V(1) vasopressin receptor antagonist SR49059 in hypertensive patients.

    Science.gov (United States)

    Thibonnier, M; Kilani, A; Rahman, M; DiBlasi, T P; Warner, K; Smith, M C; Leenhardt, A F; Brouard, R

    1999-12-01

    We assessed the clinical and pharmacological profile of the orally active V(1) vascular vasopressin (AVP) receptor nonpeptide antagonist SR49059 (SR) during the osmotic stimulation of AVP release in hypertensive patients. In a double-blind crossover-versus-placebo study, 24 untreated stage I or II essential hypertensive patients (12 whites and 12 blacks) received a single 300 mg oral dose of SR 2 hours before the stimulation of AVP secretion with a 5% hypertonic saline infusion. Hemodynamic, humoral, and hormonal parameters were monitored for up to 28 hours after drug administration. SR did not alter blood pressure or heart rate before the saline infusion and did not reduce the blood pressure increment induced by the hypertonic saline infusion. However, the blood pressure peak at the end of the hypertonic saline infusion was slightly lower in the presence of SR (P=0.04). Heart rate was significantly faster between 4 and 6 hours after SR administration (P=0.02). The rise in plasma sodium and osmolality triggered by the saline infusion was not modified by SR, but AVP release was slightly greater in the presence of SR (P<0.0003). AVP-induced aggregation of blood platelets in vitro was significantly reduced by SR, with a peak effect 2 hours after drug administration that coincided with the SR peak plasma concentration. Plasma renin activity and aldosterone before and after the saline infusion were not modified by SR. Urine volume and osmolality were not altered by SR administration. SR effects were similar in the 2 ethnic groups as well as in salt-sensitive versus salt-resistant patients. In a situation of AVP osmotic release and volume expansion in hypertensive patients, a single oral dose of the V(1) vascular AVP receptor nonpeptide antagonist SR49059, which is able to block AVP-induced platelet aggregation, exerts a transient vasodilation effect that is not associated with a sustained blood pressure reduction. SR49059 is a pure V(1) vascular receptor antagonist that

  4. Acute-phase responses in transgenic mice with CNS overexpression of IL-1 receptor antagonist.

    Science.gov (United States)

    Lundkvist, J; Sundgren-Andersson, A K; Tingsborg, S; Ostlund, P; Engfors, C; Alheim, K; Bartfai, T; Iverfeldt, K; Schultzberg, M

    1999-03-01

    The interleukin-1 (IL-1) receptor antagonist (IL-1ra) is an endogenous antagonist that blocks the effects of the proinflammatory cytokines IL-1alpha and IL-1beta by occupying the type I IL-1 receptor. Here we describe transgenic mice with astrocyte-directed overexpression of the human secreted IL-1ra (hsIL-1ra) under the control of the murine glial fibrillary acidic protein (GFAP) promoter. Two GFAP-hsIL-1ra strains have been generated and characterized further: GILRA2 and GILRA4. These strains show a brain-specific expression of the hsIL-1ra at the mRNA and protein levels. The hsIL-1ra protein was approximated to approximately 50 ng/brain in cytosolic fractions of whole brain homogenates, with no differences between male and female mice or between the two strains. Furthermore, the protein is secreted, inasmuch as the concentration of hsIL-1ra in the cerebrospinal fluid was 13 (GILRA2) to 28 (GILRA4) times higher in the transgenic mice than in the control animals. To characterize the transgenic phenotype, GILRA mice and nontransgenic controls were injected with recombinant human IL-1beta (central injection) or lipopolysaccharide (LPS, peripheral injection). The febrile response elicited by IL-1beta (50 ng/mouse icv) was abolished in hsIL-1ra-overexpressing animals, suggesting that the central IL-1 receptors were occupied by antagonist. The peripheral LPS injection (25 micrograms/kg ip) triggered a fever in overexpressing and control animals. Moreover, no differences were found in LPS-induced (100 and 1,000 micrograms/kg ip; 1 and 6 h after injection) IL-1beta and IL-6 serum levels between GILRA and wild-type mice. On the basis of these results, we suggest that binding of central IL-1 to central IL-1 receptors is not important in LPS-induced fever or LPS-induced IL-1beta and IL-6 plasma levels.

  5. 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.

  6. Structure-Based Understanding of Binding Affinity and Mode of Estrogen Receptor α Agonists and Antagonists

    Science.gov (United States)

    Barron, Mace G.

    2017-01-01

    The flexible hydrophobic ligand binding pocket (LBP) of estrogen receptor α (ERα) allows the binding of a wide variety of endocrine disruptors. Upon ligand binding, the LBP reshapes around the contours of the ligand and stabilizes the complex by complementary hydrophobic interactions and specific hydrogen bonds with the ligand. Here we present a framework for quantitative analysis of the steric and electronic features of the human ERα-ligand complex using three dimensional (3D) protein-ligand interaction description combined with 3D-QSAR approach. An empirical hydrophobicity density field is applied to account for hydrophobic contacts of ligand within the LBP. The obtained 3D-QSAR model revealed that hydrophobic contacts primarily determine binding affinity and govern binding mode with hydrogen bonds. Several residues of the LBP appear to be quite flexible and adopt a spectrum of conformations in various ERα-ligand complexes, in particular His524. The 3D-QSAR was combined with molecular docking based on three receptor conformations to accommodate receptor flexibility. The model indicates that the dynamic character of the LBP allows accommodation and stable binding of structurally diverse ligands, and proper representation of the protein flexibility is critical for reasonable description of binding of the ligands. Our results provide a quantitative and mechanistic understanding of binding affinity and mode of ERα agonists and antagonists that may be applicable to other nuclear receptors. PMID:28061508

  7. Docking-based virtual screening of potential human P2Y12 receptor antagonists

    Institute of Scientific and Technical Information of China (English)

    Hua Chen; Xianchi Dong; Minyun Zhou; Haiming Shi; Xinping Luo

    2011-01-01

    Platelet plays essential roles in hemostasis and its dysregulation can lead to arterial thrombosis. P2Y12 is an important platelet membrane adenosine diphosphate receptor,and its antagonists have been widely developed as anticoagulation agents. The current P2Y12 inhibitors available in clinical practice have not fully achieved saOsfactory antithrombotic effects, leaving room for further improvement To identify new chemical compounds as potential anticoagulation inhibitors, we constructed a three-dimensional structure model of human P2Y12 by homology modeling based on the recently reported G-protein coupled receptor Meleagris gallopavo βl adrenergic receptor. Virtual screening of the modeled P2Y12 against three subsets of small molecules from the ZINC database, namely lead-like, fragment-like, and drug-like, identified a number of compounds tbat might have high binding affinity to P2Y12.Detailed analyses of the top three compounds from each subset with the highest scores indicated that all of these compounds beard a hydrophobic bulk supplemented with a few polar atoms which bound at the ligand binding site via largely hydrophobic interactions with the receptor. This study not only provides a structure model of P2Y12 for rational design of anti-platelet inhibitors, but also identifies some potential chemicals for further development.

  8. Exploration of structure-activity relationships for dual serotonin transporter reuptake inhibitors-histamine H3 receptor antagonists.

    Science.gov (United States)

    Stocking, Emily M; Letavic, Michael A; Bonaventure, Pascal; Carruthers, Nicholas I

    2010-01-01

    Depression is a major health issue, which is routinely treated with selective serotonin reuptake inhibitors. However, although these agents display a favorable effect on mood, they often fail to improve conditions that accompany depression including cognitive impairment and fatigue. In pre-clinical studies histamine H(3) receptor antagonists have demonstrated both pro-cognitive and wake-promoting effects suggesting that the combination of a histamine H(3) receptor antagonist and a serotonin reuptake inhibitor may have utility as an antidepressant therapy. To this end we sought to introduce histamine H(3) receptor antagonist activity into both known selective serotonin reuptake inhibitors and novel templates. These efforts have afforded several series of compounds with the desired activities. Selected examples demonstrated in vivo efficacy both in pre-clinical models of depression and wakefulness.

  9. Inhibition of a slow synaptic response by a metabotropic glutamate receptor antagonist in hippocampal CA3 pyramidal cells.

    Science.gov (United States)

    Gerber, U; Lüthi, A; Gähwiler, B H

    1993-11-22

    The effects of a novel antagonist of metabotropic glutamate receptors were investigated in CA3 pyramidal cells in hippocampal slice cultures of the rat. Earlier experiments showed that selective activation of metabotropic glutamate receptors with low concentrations of an agonist, 1S, 3R-1-amino-cyclopentane-1,3-dicarboxylic acid (ACPD), induced an inward current associated with a decrease in membrane conductance and inhibition of the slow calcium-dependent potassium current. These responses were strongly and reversibly reduced by the antagonist, (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG, 0.5-1 mM). In the presence of antagonists of ionotropic glutamate receptors, stimulation of the afferent mossy fibres evoked postsynaptic responses in CA3 pyramidal cells which paralleled those observed with exogenously applied metabotropic glutamate receptor agonists, i.e. a slow inward current and a reduction of calcium-dependent potassium current. Both responses were greatly reduced by bath-applied MCPG (1 mM). These results show that MCPG acts as an effective antagonist at metabotropic glutamate receptors coupled to potassium conductances in the hippocampus. Furthermore, they confirm that glutamate release from presynaptic terminals can modulate postsynaptic properties by activation of metabotropic glutamate receptors.

  10. Naturally-Occurring Glucosinolates, Glucoraphanin and Glucoerucin, are Antagonists to Aryl Hydrocarbon Receptor as Their Chemopreventive Potency.

    Science.gov (United States)

    Abdull Razis, Ahmad Faizal; Noor, Noramaliza Mohd

    2015-01-01

    As a cytosolic transcription factor, the aryl hydrocarbon (Ah) receptor is involved in several patho- physiological events leading to immunosuppression and cancer; hence antagonists of the Ah receptor may possess chemoprevention properties. It is known to modulate carcinogen-metabolising enzymes, for instance the CYP1 family of cytochromes P450 and quinone reductase, both important in the biotransformation of many chemical carcinogens via regulating phase I and phase II enzyme systems. Utilising chemically-activated luciferase expression (CALUX) assay it was revealed that intact glucosinolates, glucoraphanin and glucoerucin, isolated from Brassica oleracea L. var. acephala sabellica and Eruca sativa ripe seeds, respectively, are such antagonists. Both glucosinolates were poor ligands for the Ah receptor; however, they effectively antagonised activation of the receptor by the avid ligand benzo[a]pyrene. Indeed, intact glucosinolate glucoraphanin was a more potent antagonist to the receptor than glucoerucin. It can be concluded that both glucosinolates effectively act as antagonists for the Ah receptor, and this may contribute to their established chemoprevention potency.

  11. A novel urotensin II receptor antagonist, KR-36996, improved cardiac function and attenuated cardiac hypertrophy in experimental heart failure.

    Science.gov (United States)

    Oh, Kwang-Seok; Lee, Jeong Hyun; Yi, Kyu Yang; Lim, Chae Jo; Park, Byung Kil; Seo, Ho Won; Lee, Byung Ho

    2017-03-15

    Urotensin II and its receptor are thought to be involved in various cardiovascular diseases such as heart failure, pulmonary hypertension and atherosclerosis. Since the regulation of the urotensin II/urotensin II receptor offers a great potential for therapeutic strategies related to the treatment of cardiovascular diseases, the study of selective and potent antagonists for urotensin II receptor is more fascinating. This study was designed to determine the potential therapeutic effects of a newly developed novel urotensin II receptor antagonist, N-(1-(3-bromo-4-(piperidin-4-yloxy)benzyl)piperidin-4-yl)benzo[b]thiophene-3-carboxamide (KR-36996), in experimental models of heart failure. KR-36996 displayed a high binding affinity (Ki=4.44±0.67nM) and selectivity for urotensin II receptor. In cell-based study, KR-36996 significantly inhibited urotensin II-induced stress fiber formation and cellular hypertrophy in H9c2UT cells. In transverse aortic constriction-induced cardiac hypertrophy model in mice, the daily oral administration of KR-36996 (30mg/kg) for 14 days significantly decreased left ventricular weight by 40% (Preceptor antagonist could efficiently attenuate both cardiac hypertrophy and dysfunction in experimental heart failure. KR-36996 may be useful as an effective urotensin II receptor antagonist for pharmaceutical or clinical applications.

  12. Fine specificity and molecular competition in SLAM family receptor signalling.

    Science.gov (United States)

    Wilson, Timothy J; Garner, Lee I; Metcalfe, Clive; King, Elliott; Margraf, Stefanie; Brown, Marion H

    2014-01-01

    SLAM family receptors regulate activation and inhibition in immunity through recruitment of activating and inhibitory SH2 domain containing proteins to immunoreceptor tyrosine based switch motifs (ITSMs). Binding of the adaptors, SAP and EAT-2 to ITSMs in the cytoplasmic regions of SLAM family receptors is important for activation. We analysed the fine specificity of SLAM family receptor phosphorylated ITSMs and the conserved tyrosine motif in EAT-2 for SH2 domain containing signalling proteins. Consistent with the literature describing dependence of CRACC (SLAMF7) on EAT-2, CRACC bound EAT-2 (KD = 0.003 μM) with approximately 2 orders of magnitude greater affinity than SAP (KD = 0.44 μM). RNA interference in cytotoxicity assays in NK92 cells showed dependence of CRACC on SAP in addition to EAT-2, indicating selectivity of SAP and EAT-2 may depend on the relative concentrations of the two adaptors. The concentration of SAP was four fold higher than EAT-2 in NK92 cells. Compared with SAP, the significance of EAT-2 recruitment and its downstream effectors are not well characterised. We identified PLCγ1 and PLCγ2 as principal binding partners for the EAT-2 tail. Both PLCγ1 and PLCγ2 are functionally important for cytotoxicity in NK92 cells through CD244 (SLAMF4), NTB-A (SLAMF6) and CRACC. Comparison of the specificity of SH2 domains from activating and inhibitory signalling mediators revealed a hierarchy of affinities for CD244 (SLAMF4) ITSMs. While binding of phosphatase SH2 domains to individual ITSMs of CD244 was weak compared with SAP or EAT-2, binding of tandem SH2 domains of SHP-2 to longer peptides containing tandem phosphorylated ITSMs in human CD244 increased the affinity ten fold. The concentration of the tyrosine phosphatase, SHP-2 was in the order of a magnitude higher than the adaptors, SAP and EAT-2. These data demonstrate a mechanism for direct recruitment of phosphatases in inhibitory signalling by ITSMs, while explaining competitive

  13. Fine Specificity and Molecular Competition in SLAM Family Receptor Signalling

    Science.gov (United States)

    Wilson, Timothy J.; Garner, Lee I.; Metcalfe, Clive; King, Elliott; Margraf, Stefanie; Brown, Marion H.

    2014-01-01

    SLAM family receptors regulate activation and inhibition in immunity through recruitment of activating and inhibitory SH2 domain containing proteins to immunoreceptor tyrosine based switch motifs (ITSMs). Binding of the adaptors, SAP and EAT-2 to ITSMs in the cytoplasmic regions of SLAM family receptors is important for activation. We analysed the fine specificity of SLAM family receptor phosphorylated ITSMs and the conserved tyrosine motif in EAT-2 for SH2 domain containing signalling proteins. Consistent with the literature describing dependence of CRACC (SLAMF7) on EAT-2, CRACC bound EAT-2 (KD = 0.003 μM) with approximately 2 orders of magnitude greater affinity than SAP (KD = 0.44 μM). RNA interference in cytotoxicity assays in NK92 cells showed dependence of CRACC on SAP in addition to EAT-2, indicating selectivity of SAP and EAT-2 may depend on the relative concentrations of the two adaptors. The concentration of SAP was four fold higher than EAT-2 in NK92 cells. Compared with SAP, the significance of EAT-2 recruitment and its downstream effectors are not well characterised. We identified PLCγ1 and PLCγ2 as principal binding partners for the EAT-2 tail. Both PLCγ1 and PLCγ2 are functionally important for cytotoxicity in NK92 cells through CD244 (SLAMF4), NTB-A (SLAMF6) and CRACC. Comparison of the specificity of SH2 domains from activating and inhibitory signalling mediators revealed a hierarchy of affinities for CD244 (SLAMF4) ITSMs. While binding of phosphatase SH2 domains to individual ITSMs of CD244 was weak compared with SAP or EAT-2, binding of tandem SH2 domains of SHP-2 to longer peptides containing tandem phosphorylated ITSMs in human CD244 increased the affinity ten fold. The concentration of the tyrosine phosphatase, SHP-2 was in the order of a magnitude higher than the adaptors, SAP and EAT-2. These data demonstrate a mechanism for direct recruitment of phosphatases in inhibitory signalling by ITSMs, while explaining competitive

  14. Multivalent benzene polyphosphate derivatives are non-Ca(2+)-mobilizing Ins(1,4,5)P3 receptor antagonists.

    Science.gov (United States)

    Mills, Stephen J; Luyten, Tomas; Erneux, Christophe; Parys, Jan B; Potter, Barry V L

    2012-12-01

    Inositol 1,4,5-trisphosphate [Ins(1,4,5)P31] mobilizes intracellular Ca(2+) through the Ins(1,4,5)P3 receptor [InsP3R]. Although some progress has been made in the design of synthetic InsP3R partial agonists and antagonists, there are still few examples of useful small molecule competitive antagonists. A "multivalent" approach is explored and new dimeric polyphosphorylated aromatic derivatives were designed, synthesized and biologically evaluated. The established weak InsP3R ligand benzene 1,2,4-trisphosphate [Bz(1,2,4)P32] is dimerized through its 5-position in two different ways, first directly as the biphenyl derivative biphenyl 2,2',4,4',5,5'-hexakisphosphate, [BiPh(2,2',4,4',5,5')P68] and with its regioisomeric biphenyl 3,3',4,4',5,5'-hexakisphosphate [BiPh(3,3',4,4',5,5')P611]. Secondly, a linker motif is introduced in a flexible ethylene-bridged dimer (9) with its corresponding 1,2-bisphosphate dimer (10), both loosely analogous to the very weak antagonist 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA 7). In permeabilized L15 fibroblasts overexpressing type 1 InsP3R, BiPh(2,2',4,4',5,5')P6 (8) inhibits Ins(1,4,5)P3-induced Ca(2+) release in a apparently competitive fashion [IC50 187 nM] and the Bz(1,2,4)P3 dimer (9) is only slightly weaker [IC50 380 nM]. Compounds were also evaluated against type I Ins(1,4,5)P3 5-phosphatase. All compounds are resistant to dephosphorylation, with BiPh(2,2',4,4',5,5')P6 (8), being the most effective inhibitor of any biphenyl derivative synthesized to date [IC50 480 nM] and the Bz(1,2,4)P3 ethylene dimer (9) weaker [IC50 3.55 μM]. BiPh(3,3',4,4',5,5')P6 (11) also inhibits 5-phosphatase [IC50 730 nM] and exhibits unexpected Ca(2+) releasing activity [EC50 800 nM]. Thus, relocation of only a single mirrored phenyl phosphate group in (11) from that of antagonist (8) does not markedly change enzyme inhibitory activity, but elicits a dramatic switch in Ca(2+)-releasing activity. Such new agents demonstrate the

  15. The Administration of Levocabastine, a NTS2 Receptor Antagonist, Modifies Na(+), K(+)-ATPase Properties.

    Science.gov (United States)

    Gutnisky, Alicia; López Ordieres, María Graciela; Rodríguez de Lores Arnaiz, Georgina

    2016-06-01

    Neurotensin behaves as a neuromodulator or as a neurotransmitter interacting with NTS1 and NTS2 receptors. Neurotensin in vitro inhibits synaptosomal membrane Na(+), K(+)-ATPase activity. This effect is prevented by administration of SR 48692 (antagonist for NTS1 receptor). The administration of levocabastine (antagonist for NTS2 receptor) does not prevent Na(+), K(+)-ATPase inhibition by neurotensin when the enzyme is assayed with ATP as substrate. Herein levocabastine effect on Na(+), K(+)-ATPase K(+) site was explored. For this purpose, levocabastine was administered to rats and K(+)-p-nitrophenylphosphatase (K(+)-p-NPPase) activity in synaptosomal membranes and [(3)H]-ouabain binding to cerebral cortex membranes were assayed in the absence (basal) and in the presence of neurotensin. Male Wistar rats were administered with levocabastine (50 μg/kg, i.p., 30 min) or the vehicle (saline solution). Synaptosomal membranes were obtained from cerebral cortex by differential and gradient centrifugation. The activity of K(+)-p-NPPase was determined in media laking or containing ATP plus NaCl. In such phosphorylating condition enzyme behaviour resembles that observed when ATP hydrolyses is recorded. In the absence of ATP plus NaCl, K(+)-p-NPPase activity was similar for levocabastine or vehicle injected (roughly 11 μmole hydrolyzed substrate per mg protein per hour). Such value remained unaltered by the presence of 3.5 × 10(-6) M neurotensin. In the phosphorylating medium, neurotensin decreased (32 %) the enzyme activity in membranes obtained from rats injected with the vehicle but failed to alter those obtained from rats injected with levocabastine. Levocabastine administration enhanced (50 %) basal [(3)H]-ouabain binding to cerebral cortex membranes but failed to modify neurotensin inhibitory effect on this ligand binding. It is concluded that NTS2 receptor blockade modifies the properties of neuronal Na(+), K(+)-ATPase and that neurotensin effect on Na(+), K

  16. Prospective therapeutic agents for obesity: molecular modification approaches of centrally and peripherally acting selective cannabinoid 1 receptor antagonists.

    Science.gov (United States)

    Sharma, Mayank Kumar; Murumkar, Prashant R; Kanhed, Ashish M; Giridhar, Rajani; Yadav, Mange Ram

    2014-05-22

    Presently, obesity is one of the major health problems in the developed as well as developing countries due to lack of physical work and increasing sedentary life style. Endocannabinoid system (ECS) and especially cannabinoid 1 (CB1) receptor play a key role in energy homeostasis. Food intake and energy storage is enhanced due to the stimulation of ECS hence, inhibition of ECS by blocking CB1 receptors could be a promising approach in the treatment of obesity. Rimonabant, a diaryl pyrazole was the first potent and selective CB1 receptor antagonist that was introduced into the market in 2006 but was withdrawn in 2008 due to its psychiatric side effects. Researchers all over the world are interested to develop peripherally acting potent and selective CB1 receptor antagonists having a better pharmacokinetic profile and therapeutic index. In this development process, pyrazole ring of rimonabant has been replaced by different bioisosteric scaffolds like pyrrole, imidazole, triazole, pyrazoline, pyridine etc. Variations in substituents around the pyrazole ring have also been done. New strategies were also employed for minimizing the psychiatric side effects by making more polar and less lipophilic antagonists/inverse agonists along with neutral antagonists acting peripherally. It has been observed that some of the peripherally acting compounds do not show adverse effects and could be used as potential leads for the further design of selective CB1 receptor antagonists. Chemical modification strategies used for the development of selective CB1 receptor antagonists are discussed here in this review. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  17. Anxiolytic-like effects of mGlu1 and mGlu5 receptor antagonists in rats.

    Science.gov (United States)

    Pietraszek, Małgorzata; Sukhanov, Ilia; Maciejak, Piotr; Szyndler, Janusz; Gravius, Andreas; Wisłowska, Aleksandra; Płaźnik, Adam; Bespalov, Anton Y; Danysz, Wojciech

    2005-05-02

    The purpose of the present study was to compare anxiolytic activity of the metabotropic glutamate receptor 1 (mGlu) antagonist, EMQMCM ((3-ethyl-2-methyl-quinolin-6-yl)-(4-methoxy-cyclohexyl)-methanone methanesulfonate) and the mGlu5 receptor antagonist MTEP ([(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine) and MPEP (2-methyl-6-(phenylethynyl)pyridine) in animal models of anxiety. In the elevated plus maze, diazepam (1 mg/kg), but not the mGlu1 or mGlu5 receptor antagonists induced anxiolytic-like effects. Meanwhile, MTEP (2.5 and 5 mg/kg), EMQMCM (5 mg/kg), and diazepam (2 mg/kg) all significantly inhibited fear potentiated startle. In the contextual fear conditioning test, MTEP (1.25 and 2.5 but not 5 mg/kg) and EMQMCM (0.6 to 5 mg/kg) attenuated freezing responding. In the Geller-Seifter conflict test, MPEP (1 and 3 mg/kg), MTEP (3 mg/kg), chlordiazepoxide (10 and 20 mg/kg) and midazolam (1 mg/kg) all facilitated punished responding, while ECMQCM failed to produce any significant effects up to 3 mg/kg dose. To summarise, the present data further support a significant anxiolytic potential of group I mGlu receptor antagonists, while suggesting the effects of mGlu1 receptor antagonists may depend on the experimental procedure and may be qualitatively different from those of mGlu5 receptor antagonists.

  18. Salvianolic Acid A, as a Novel ETA Receptor Antagonist, Shows Inhibitory Effects on Tumor in Vitro

    Directory of Open Access Journals (Sweden)

    Qiao Zhang

    2016-08-01

    Full Text Available Endothelin-1 (ET-1 autocrine and paracrine signaling modulate cell proliferation of tumor cells by activating its receptors, endothelin A receptor (ETAR and endothelin B receptor (ETBR. Dysregulation of ETAR activation promotes tumor development and progression. The potential of ETAR antagonists and the dual-ETAR and ETBR antagonists as therapeutic approaches are under preclinical and clinical studies. Salvianolic acid A (Sal A is a hydrophilic polyphenolic derivative isolated from Salvia miltiorrhiza Bunge (Danshen, which has been reported as an anti-cancer and cardio-protective herbal medicine. In this study, we demonstrate that Sal A inhibits ETAR activation induced by ET-1 in both recombinant and endogenous ETAR expression cell lines. The IC50 values were determined as 5.7 µM in the HEK293/ETAR cell line and 3.14 µM in HeLa cells, respectively. Furthermore, our results showed that Sal A suppressed cell proliferation and extended the doubling times of multiple cancer cells, including HeLa, DU145, H1975, and A549 cell lines. In addition, Sal A inhibited proliferation of DU145 cell lines stimulated by exogenous ET-1 treatment. Moreover, the cytotoxicity and cardio-toxicity of Sal A were assessed in human umbilical vein endothelial cells (HUVEC and Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs, which proved that Sal A demonstrates no cytotoxicity or cardiotoxicity. Collectively, our findings indicate that Sal A is a novel anti-cancer candidate through targeting ETAR.

  19. Histamine-2 receptor antagonist famotidine modulates cardiac stem cell characteristics in hypertensive heart disease

    Directory of Open Access Journals (Sweden)

    Sherin Saheera

    2017-10-01

    Full Text Available Background Cardiac stem cells (CSCs play a vital role in cardiac homeostasis. A decrease in the efficiency of cardiac stem cells is speculated in various cardiac abnormalities. The maintenance of a healthy stem cell population is essential for the prevention of adverse cardiac remodeling leading to cardiac failure. Famotidine, a histamine-2 receptor antagonist, is currently used to treat ulcers of the stomach and intestines. In repurposing the use of the drug, reduction of cardiac hypertrophy and improvement in cardiac function of spontaneously hypertensive rats (SHR was reported by our group. Given that stem cells are affected in cardiac pathologies, the effect of histamine-2 receptor antagonism on CSC characteristics was investigated. Methods To examine whether famotidine has a positive effect on CSCs, spontaneously hypertensive rats (SHR treated with the drug were sacrificed; and CSCs isolated from atrial appendages was evaluated. Six-month-old male SHRs were treated with famotidine (30 mg/kg/day for two months. The effect of famotidine treatment on migration, proliferation and survival of CSCs was compared with untreated SHRs and normotensive Wistar rats. Results Functional efficiency of CSCs from SHR was compromised relative to that in Wistar rat. Famotidine increased the migration and proliferation potential, along with retention of stemness of CSCs in treated SHRs. Cellular senescence and oxidative stress were also reduced. The expression of H2R was unaffected by the treatment. Discussion As anticipated, CSCs from SHRs were functionally impaired. Stem cell attributes of famotidine-treated SHRs was comparable to that of Wistar rats. Therefore, in addition to being cardioprotective, the histamine 2 receptor antagonist modulated cardiac stem cells characteristics. Restoration of stem cell efficiency by famotidine is possibly mediated by reduction of oxidative stress as the expression of H2R was unaffected by the treatment. Maintenance of

  20. The Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome (TRA*CER) trial: study design and rationale.

    Science.gov (United States)

    2009-09-01

    The protease-activated receptor 1 (PAR-1), the main platelet receptor for thrombin, represents a novel target for treatment of arterial thrombosis, and SCH 530348 is an orally active, selective, competitive PAR-1 antagonist. We designed TRA*CER to evaluate the efficacy and safety of SCH 530348 compared with placebo in addition to standard of care in patients with non-ST-segment elevation (NSTE) acute coronary syndromes (ACS) and high-risk features. TRA*CER is a prospective, randomized, double-blind, multicenter, phase III trial with an original estimated sample size of 10,000 subjects. Our primary objective is to demonstrate that SCH 530348 in addition to standard of care will reduce the incidence of the composite of cardiovascular death, myocardial infarction (MI), stroke, recurrent ischemia with rehospitalization, and urgent coronary revascularization compared with standard of care alone. Our key secondary objective is to determine whether SCH 530348 will reduce the composite of cardiovascular death, MI, or stroke compared with standard of care alone. Secondary objectives related to safety are the composite of moderate and severe GUSTO bleeding and clinically significant TIMI bleeding. The trial will continue until a predetermined minimum number of centrally adjudicated primary and key secondary end point events have occurred and all subjects have participated in the study for at least 1 year. The TRA*CER trial is part of the large phase III SCH 530348 development program that includes a concomitant evaluation in secondary prevention. TRA*CER will define efficacy and safety of the novel platelet PAR-1 inhibitor SCH 530348 in the treatment of high-risk patients with NSTE ACS in the setting of current treatment strategies.

  1. Impaired effect of activation of rat hippocampal 5-HT7 receptors, induced by treatment with the 5-HT7 receptor antagonist SB 269970.

    Science.gov (United States)

    Kusek, M; Sowa, J; Tokarski, K; Hess, G

    2015-04-01

    Effects of the 5-HT(7) receptor antagonist SB 269970, administered for 14 days (1.25 mg/kg), were studied in ex vivo slices of rat hippocampus. To activate the 5-HT(7) receptor, 5-carboxamidotryptamine (5-CT, 200 nM) was applied in the presence of WAY 100635 (2 μM), a 5-HT(1A) receptor antagonist. In contrast to control preparations, no 5-HT(7) receptor-mediated increase in excitability nor depolarization and an increase in the input resistance of CA1 and CA3 pyramidal neurons were present in slices prepared from rats treated with SB 269970. The treatment also abolished the stimulatory effect of 5-HT(7) receptor activation on spontaneous excitatory postsynaptic currents recorded from CA1 stratum radiatum/lacunosum-moleculare interneurons. These data demonstrate that repeated administration of SB 269970 impairs the reactivity of the CA1 hippocampal neuronal network to 5-HT(7) receptor activation.

  2. Structural and pharmacological characterization of phenylalanine-based AMPA receptor antagonists at kainate receptors

    DEFF Research Database (Denmark)

    Venskutonyte, Raminta; Frydenvang, Karla; Valadés, Elena Antón

    2012-01-01

    . A new series of phenylalanine derivatives that target iGluRs was reported to bind AMPA receptors. Herein we report our studies of these compounds at the kainate receptors GluK1-3. Several compounds bind with micromolar affinity at GluK1 and GluK3, but do not bind GluK2. The crystal structure of the most...... potent compound in the ligand binding domain of GluK1 revealed different modes of binding to GluK1 and GluA2, due primarily to residues Ser741 (GluK1) and Met729 (GluA2). The compound was shown to be slightly more potent at GluK1 than at AMPA receptors and to induce a domain closure similar...

  3. Structural complexes of the agonist, inverse agonist and antagonist bound C5a receptor: insights into pharmacology and signaling.

    Science.gov (United States)

    Rana, Soumendra; Sahoo, Amita Rani; Majhi, Bharat Kumar

    2016-04-26

    The C5a receptor (C5aR) is a pharmacologically important G-protein coupled receptor (GPCR) that interacts with (h)C5a, by recruiting both the "orthosteric" sites (site1 at the N-terminus and site2 at the ECS, extra cellular surface) on C5aR in a two site-binding model. However, the complex pharmacological landscape and the distinguishing chemistry operating either at the "orthosteric" site1 or at the functionally important "orthosteric" site2 of C5aR are still not clear, which greatly limits the understanding of C5aR pharmacology. One of the major bottlenecks is the lack of an experimental structure or a refined model structure of C5aR with appropriately defined active sites. The study attempts to understand the pharmacology at the "orthosteric" site2 of C5aR rationally by generating a highly refined full-blown model structure of C5aR through advanced molecular modeling techniques, and further subjecting it to automated docking and molecular dynamics (MD) studies in the POPC bilayer. The first series of structural complexes of C5aR respectively bound to a linear native peptide agonist ((h)C5a-CT), a small molecule inverse agonist (NDT) and a cyclic peptide antagonist (PMX53) are reported, apparently establishing the unique pharmacological landscape of the "orthosteric" site2, which also illustrates an energetically distinct but coherent competitive chemistry ("cation-π" vs. "π-π" interactions) involved in distinguishing the established ligands known for targeting the "orthosteric" site2 of C5aR. Over a total of 1 μs molecular dynamics (MD) simulation in the POPC bilayer, it is evidenced that while the agonist prefers a "cation-π" interaction, the inverse agonist prefers a "cogwheel/L-shaped" interaction in contrast to the "edge-to-face/T-shaped" type π-π interactions demonstrated by the antagonist by engaging the F275(7.28) of the C5aR. In the absence of a NMR or crystallographically guided model structure of C5aR, the computational model complexes not only

  4. Effect of the selective vasopressin V2 receptor antagonists in hepatic cirrhosis patients with ascites: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Shao-hui TANG

    2013-07-01

    Full Text Available Objective To evaluate the efficacy and safety of selective vasopressin V2 receptor antagonists in the treatment of hepatic cirrhosis patients with ascites. Methods PubMed, EMBASE, Web of Science, The Cochrane Central Register of Controlled Trials, Database for Chinese Technical Periodical (VIP, Chinese Journal Full-Text Database (CNKI, and Wan Fang Digital Journal Full-text Database were retrieved to collect clinical randomized controlled trials of hepatic cirrhosis with ascites treated by selective vasopressin V2 receptor antagonists. Meta analysis was performed by using Review Manager 5.0. Results Nine randomized controlled trials including 1884 patients met the inclusion criteria. Meta-analysis showed that: 1 The selective vasopressin V2 receptor antagonists were associated with a significant reduction in body weight compared with placebo (WMD=–1.98kg, 95%CI:–3.24-–0.72kg, P=0.002. Treatment with selective vasopressin V2 receptor antagonists was associated with an improvement of low serum sodium concentration compared to placebo (WMD=3.74mmol/L, 95%CI: 0.91-6.58mmol/L, P=0.01. The percentage of patients with worsening ascites was higher in the group of patients treated with placebo (RR=0.51, 95%CI: 0.34-0.77, P=0.001. 2 The amplitude of increased urine volume was obviously higher in selective vasopressin V2 receptor antagonists group than in placebo group (WMD=1437.65ml, 95%CI: 649.01-2226.30ml, P=0.0004. The difference of serum creatinine in the selective vasopressin V2 receptor antagonists group was not statistically significant compared with the control group (WMD=–3.49μmol/L, 95%CI: –12.54¬5.56μmol/L, P=0.45. 3 There was no statistical significance between the two groups in the heart rate, systolic pressure, diastolic pressure and mortality (P>0.05. The rate of other adverse reactions was higher in the selective vasopressin V2 receptor antagonists group compared with that of placebo group (P=0.003. Conclusion

  5. Synthesis and evaluation of carbamate and aryl ether substituted pyrazinones as corticotropin releasing factor-1 (CRF₁) receptor antagonists.

    Science.gov (United States)

    Ahuja, Vijay T; Hartz, Richard A; Molski, Thaddeus F; Mattson, Gail K; Lentz, Kimberley A; Grace, James E; Lodge, Nicholas J; Bronson, Joanne J; Macor, John E

    2016-05-01

    A series of pyrazinone-based compounds incorporating either carbamate or aryl ether groups was synthesized and evaluated as corticotropin-releasing factor-1 (CRF1) receptor antagonists. Structure-activity relationship studies led to the identification of highly potent CRF1 receptor antagonists 14a (IC50=0.74 nM) and 14b (IC50=1.9 nM). The synthesis, structure-activity relationships and in vitro metabolic stability properties of compounds in this series will be described. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. The anticancer estrogen receptor antagonist tamoxifen impairs consolidation of inhibitory avoidance memory through estrogen receptor alpha.

    Science.gov (United States)

    Lichtenfels, Martina; Dornelles, Arethuza da Silva; Petry, Fernanda Dos Santos; Blank, Martina; de Farias, Caroline Brunetto; Roesler, Rafael; Schwartsmann, Gilberto

    2017-09-02

    Over two-thirds of women with breast cancer have positive tumors for hormone receptors, and these patients undergo treatment with endocrine therapy, tamoxifen being the most widely used agent. Despite being very effective in breast cancer treatment, tamoxifen is associated with side effects that include cognitive impairments. However, the specific aspects and mechanisms underlying these impairments remain to be characterized. Here, we have investigated the effects of tamoxifen and interaction with estrogen receptors on formation of memory for inhibitory avoidance conditioning in female rats. In the first experiment, Wistar female rats received a single oral dose of tamoxifen (1, 3, or 10 mg/kg) or saline by gavage immediately after training and were tested for memory consolidation 24 h after training. In the second experiment, rats received a single dose of 1 mg/kg tamoxifen or saline by gavage 3 h after training and were tested 24 h after training for memory consolidation. In the third experiment, rats received a subcutaneous injection with estrogen receptor α agonist or estrogen receptor beta agonist 30 min before the training. After training, rats received a single oral dose of tamoxifen 1 mg/kg or saline and were tested 24 h after training. In the fourth experiment, rats were trained and tested 24 h later. Immediately after test, rats received a single dose of tamoxifen (1 mg/kg) or saline by gavage and were given four additional daily test trials followed by a re-instatement. Tamoxifen at 1 mg/kg impaired memory consolidation when given immediately after training and the estrogen receptor alpha agonist improved the tamoxifen-related memory impairment. Moreover, tamoxifen impairs memory consolidation of the test. These findings indicate that estrogen receptors regulate the early phase of memory consolidation and the effects of tamoxifen on memory consolidation.

  7. Striatal pre- and postsynaptic profile of adenosine A(2A receptor antagonists.

    Directory of Open Access Journals (Sweden)

    Marco Orru

    Full Text Available Striatal adenosine A(2A receptors (A(2ARs are highly expressed in medium spiny neurons (MSNs of the indirect efferent pathway, where they heteromerize with dopamine D(2 receptors (D(2Rs. A(2ARs are also localized presynaptically in cortico-striatal glutamatergic terminals contacting MSNs of the direct efferent pathway, where they heteromerize with adenosine A(1 receptors (A(1Rs. It has been hypothesized that postsynaptic A(2AR antagonists should be useful in Parkinson's disease, while presynaptic A(2AR antagonists could be beneficial in dyskinetic disorders, such as Huntington's disease, obsessive-compulsive disorders and drug addiction. The aim or this work was to determine whether selective A(2AR antagonists may be subdivided according to a preferential pre- versus postsynaptic mechanism of action. The potency at blocking the motor output and striatal glutamate release induced by cortical electrical stimulation and the potency at inducing locomotor activation were used as in vivo measures of pre- and postsynaptic activities, respectively. SCH-442416 and KW-6002 showed a significant preferential pre- and postsynaptic profile, respectively, while the other tested compounds (MSX-2, SCH-420814, ZM-241385 and SCH-58261 showed no clear preference. Radioligand-binding experiments were performed in cells expressing A(2AR-D(2R and A(1R-A(2AR heteromers to determine possible differences in the affinity of these compounds for different A(2AR heteromers. Heteromerization played a key role in the presynaptic profile of SCH-442416, since it bound with much less affinity to A(2AR when co-expressed with D(2R than with A(1R. KW-6002 showed the best relative affinity for A(2AR co-expressed with D(2R than co-expressed with A(1R, which can at least partially explain the postsynaptic profile of this compound. Also, the in vitro pharmacological profile of MSX-2, SCH-420814, ZM-241385 and SCH-58261 was is in accordance with their mixed pre- and postsynaptic profile

  8. Urinary responses to acute moxonidine are inhibited by natriuretic peptide receptor antagonist.

    Science.gov (United States)

    El-Ayoubi, Rouwayda; Menaouar, Ahmed; Gutkowska, Jolanta; Mukaddam-Daher, Suhayla

    2005-05-01

    We have previously shown that acute intravenous injections of moxonidine and clonidine increase plasma atrial natriuretic peptide (ANP), a vasodilator, diuretic and natriuretic hormone. We hypothesized that moxonidine stimulates the release of ANP, which would act on its renal receptors to cause diuresis and natriuresis, and these effects may be altered in hypertension. Moxonidine (0, 10, 50, 100 or 150 microg in 300 microl saline) and clonidine (0, 1, 5 or 10 microg in 300 microl saline) injected intravenously in conscious normally hydrated normotensive Sprague-Dawley rats (SD, approximately 200 g) and 12-14-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) dose-dependently stimulated diuresis, natriuresis, kaliuresis and cGMP excretion, with these effects being more pronounced during the first hour post-injection. The actions of 5 microg clonidine and 50 microg moxonidine were inhibited by yohimbine, an alpha2-adrenoceptor antagonist, and efaroxan, an imidazoline I1-receptor antagonist. Moxonidine (100 microg) stimulated (P<0.01) diuresis in SHR (0.21+/-0.04 vs 1.16+/-0.06 ml h(-1) 100 g(-1)), SD (0.42+/-0.06 vs 1.56+/-0.19 ml h(-1) 100 g(-1)) and WKY (0.12+/-0.04 vs 1.44+/-0.21 ml h(-1) 100 g(-1)). Moxonidine-stimulated urine output was lower in SHR than in SD and WKY. Moxonidine-stimulated sodium and potassium excretions were lower in SHR than in SD, but not WKY, demonstrating an influence of strain but not of pressure. Pretreatment with the natriuretic peptide antagonist anantin (5 or 10 microg) resulted in dose-dependent inhibition of moxonidine-stimulated urinary actions. Anantin (10 microg) inhibited (P<0.01) urine output to 0.38+/-0.06, 0.12+/-0.01, and 0.16+/-0.04 ml h(-1) 100 g(-1) in SD, WKY, and SHR, respectively. Moxonidine increased (P<0.01) plasma ANP in SD (417+/-58 vs 1021+/-112 pg ml(-1)) and WKY (309+/-59 vs 1433+/-187 pg ml(-1)), and in SHR (853+/-96 vs 1879+/-229 pg ml(-1)). These results demonstrate that natriuretic

  9. Sulforaphane is not an effective antagonist of the human pregnane X-receptor in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Poulton, Emma Jane [Center for Ecogenetics and Environmental Health, University of Washington (United States); Department of Environmental and Occupational Health Sciences, University of Washington (United States); Levy, Lisa [Public Health Sciences Division, Fred Hutchinson Cancer Research Center (United States); Lampe, Johanna W. [Center for Ecogenetics and Environmental Health, University of Washington (United States); Public Health Sciences Division, Fred Hutchinson Cancer Research Center (United States); Shen, Danny D. [Center for Ecogenetics and Environmental Health, University of Washington (United States); Department of Pharmaceutics, University of Washington (United States); Tracy, Julia [Center for Ecogenetics and Environmental Health, University of Washington (United States); Department of Environmental and Occupational Health Sciences, University of Washington (United States); Shuhart, Margaret C. [Division of Gastroenterology, Department of Medicine (United States); Thummel, Kenneth E. [Center for Ecogenetics and Environmental Health, University of Washington (United States); Department of Pharmaceutics, University of Washington (United States); Eaton, David L., E-mail: deaton@uw.edu [Center for Ecogenetics and Environmental Health, University of Washington (United States); Department of Environmental and Occupational Health Sciences, University of Washington (United States); Department of Pharmaceutics, University of Washington (United States)

    2013-01-01

    Sulforaphane (SFN), is an effective in vitro antagonist of ligand activation of the human pregnane and xenobiotic receptor (PXR). PXR mediated CYP3A4 up-regulation is implicated in adverse drug-drug interactions making identification of small molecule antagonists a desirable therapeutic goal. SFN is not an antagonist to mouse or rat PXR in vitro; thus, normal rodent species are not suitable as in vivo models for human response. To evaluate whether SFN can effectively antagonize ligand activation of human PXR in vivo, a three-armed, randomized, crossover trial was conducted with 24 healthy adults. The potent PXR ligand — rifampicin (300 mg/d) was given alone for 7 days in arm 1, or in daily combination with 450 μmol SFN (Broccoli Sprout extract) in arm 2; SFN was given alone in arm 3. Midazolam as an in vivo phenotype marker of CYP3A was administered before and after each treatment arm. Rifampicin alone decreased midazolam AUC by 70%, indicative of the expected increase in CYP3A4 activity. Co-treatment with SFN did not reduce CYP3A4 induction. Treatment with SFN alone also did not affect CYP3A4 activity in the cohort as a whole, although in the subset with the highest basal CYP3A4 activity there was a statistically significant increase in midazolam AUC (i.e., decrease in CYP3A4 activity). A parallel study in humanized PXR mice yielded similar results. The parallel effects of SFN between humanized PXR mice and human subjects demonstrate the predictive value of humanized mouse models in situations where species differences in ligand-receptor interactions preclude the use of a native mouse model for studying human ligand-receptor pharmacology. -- Highlights: ► The effects of SFN on PXR mediated CYP3A4 induction in humanized PXR mice and humans were examined. ► SFN had no effect on rifampicin mediated CYP3A4 induction in humans or humanized mice. ► SFN had a modest effect on basal CYP3A4 activity among subjects with higher baseline activity. ► Humanized PXR

  10. The angiotensin II type 1 receptor antagonist Losartan binds and activates bradykinin B2 receptor signaling

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Olsen, Kristine Boisen; Erikstrup, Niels;

    2011-01-01

    The angiotensin II type 1 receptor (AT1R) blocker (ARB) Losartan has cardioprotective effects during ischemia-reperfusion injury and inhibits reperfusion arrhythmias -effects that go beyond the benefits of lowering blood pressure. The renin-angiotensin and kallikrein-kinin systems are intricately...

  11. Bone Morphogenetic Protein Type I Receptor Antagonists Decrease Growth and Induce Cell Death of Lung Cancer Cell Lines

    Science.gov (United States)

    Langenfeld, Elaine; Hong, Charles C.; Lanke, Gandhi; Langenfeld, John

    2013-01-01

    Bone morphogenetic proteins (BMPs) are highly conserved morphogens that are essential for normal development. BMP-2 is highly expressed in the majority of non-small cell lung carcinomas (NSCLC) but not in normal lung tissue or benign lung tumors. The effects of the BMP signaling cascade on the growth and survival of cancer cells is poorly understood. We show that BMP signaling is basally active in lung cancer cell lines, which can be effectively inhibited with selective antagonists of the BMP type I receptors. Lung cancer cell lines express alk2, alk3, and alk6 and inhibition of a single BMP receptor was not sufficient to decrease signaling. Inhibition of more than one type I receptor was required to decrease BMP signaling in lung cancer cell lines. BMP receptor antagonists and silencing of BMP type I receptors with siRNA induced cell death, inhibited cell growth, and caused a significant decrease in the expression of inhibitor of differentiation (Id1, Id2, and Id3) family members, which are known to regulate cell growth and survival in many types of cancers. BMP receptor antagonists also decreased clonogenic cell growth. Knockdown of Id3 significantly decreased cell growth and induced cell death of lung cancer cells. H1299 cells stably overexpressing Id3 were resistant to growth suppression and induction of cell death induced by the BMP antagonist DMH2. These studies suggest that BMP signaling promotes cell growth and survival of lung cancer cells, which is mediated through its regulation of Id family members. Selective antagonists of the BMP type I receptors represents a potential means to pharmacologically treat NSCLC and other carcinomas with an activated BMP signaling cascade. PMID:23593444

  12. Critical Evaluation of P2X7 Receptor Antagonists in Selected Seizure Models

    Science.gov (United States)

    Fischer, Wolfgang; Franke, Heike; Krügel, Ute; Müller, Heiko; Dinkel, Klaus; Lord, Brian; Letavic, Michael A.; Henshall, David C.; Engel, Tobias

    2016-01-01

    The ATP-gated P2X7 receptor (P2X7R) is a non-selective cation channel which senses high extracellular ATP concentrations and has been suggested as a target for the treatment of neuroinflammation and neurodegenerative diseases. The use of P2X7R antagonists may therefore be a viable approach for treating CNS pathologies, including epileptic disorders. Recent studies showed anticonvulsant potential of P2X7R antagonists in certain animal models. To extend this work, we tested three CNS-permeable P2X7R blocker (Brilliant Blue G, AFC-5128, JNJ-47965567) and a natural compound derivative (tanshinone IIA sulfonate) in four well-characterized animal seizure models. In the maximal electroshock seizure threshold test and the pentylenetetrazol (PTZ) seizure threshold test in mice, none of the four compounds demonstrated anticonvulsant effects when given alone. Notably, in combination with carbamazepine, both AFC-5128 and JNJ-47965567 increased the threshold in the maximal electroshock seizure test. In the PTZ-kindling model in rats, useful for testing antiepileptogenic activities, Brilliant Blue G and tanshinone exhibited a moderate retarding effect, whereas the potent P2X7R blocker AFC-5128 and JNJ-47965567 showed a significant and long-lasting delay in kindling development. In fully kindled rats, the investigated compounds revealed modest effects to reduce the mean seizure stage. Furthermore, AFC-5128- and JNJ-47965567-treated animals displayed strongly reduced Iba 1 and GFAP immunoreactivity in the hippocampal CA3 region. In summary, our results show that P2X7R antagonists possess no remarkable anticonvulsant effects in the used acute screening tests, but can attenuate chemically-induced kindling. Further studies would be of interest to support the concept that P2X7R signalling plays a crucial role in the pathogenesis of epileptic disorders. PMID:27281030

  13. Effect of α₇ nicotinic acetylcholine receptor agonists and antagonists on motor function in mice.

    Science.gov (United States)

    Welch, Kevin D; Pfister, James A; Lima, Flavia G; Green, Benedict T; Gardner, Dale R

    2013-02-01

    Nicotinic acetylcholine receptors (nAChRs) are ligand-gated cation channels found throughout the body, and serve to mediate diverse physiological functions. Muscle-type nAChRs located in the motor endplate region of muscle fibers play an integral role in muscle contraction and thus motor function. The toxicity and teratogenicity of many plants (which results in millions of dollars in losses annually to the livestock industry) are due to various toxins that bind to nAChRs including deltaline and methyllycaconitine (MLA) from larkspur (Delphinium) species, and nicotine and anabasine from tobacco (Nicotiana) species. The primary result of the actions of these alkaloids at nAChRs is neuromuscular paralysis and respiratory failure. The objective of this study was to further characterize the motor coordination deficiencies that occur upon exposure to a non-lethal dose of nAChR antagonists MLA and deltaline as well as nAChR agonists nicotine and anabasine. We evaluated the effect of nAChR agonists and antagonists on the motor function and coordination in mice using a balance beam, grip strength meter, rotarod, open field analysis and tremor monitor. These analyses demonstrated that within seconds after treatment the mice had significant loss of motor function and coordination that lasted up to 1 min, followed by a short period of quiescence. Recovery to normal muscle coordination was rapid, typically within approximately 10 min post-dosing. However, mice treated with the nAChR agonist nicotine and anabasine required a slightly longer time to recover some aspects of normal muscle function in comparison to mice treated with the nAChR antagonist MLA or deltaline.

  14. Pre-treatment with the NMDA receptor glycine-binding site antagonist L-701,324 improves pharmacosensitivity in a mouse kindling model.

    Science.gov (United States)

    Zellinger, Christina; Salvamoser, Josephine D; Soerensen, Jonna; van Vliet, Erwin A; Aronica, Eleonora; Gorter, Jan; Potschka, Heidrun

    2014-05-01

    The glycine co-agonist binding site of the N-methyl-D-aspartat (NMDA) receptor is discussed as an interesting target for different central nervous system diseases. Antagonism at this co-agonist site has been suggested as an alternative to the use of non-competitive or competitive NMDA receptor antagonists, which are associated with a pronounced adverse effect profile in chronic epilepsy models and epilepsy patients. In the present study, we addressed the hypothesis that sub-chronic administration of the glycine-binding site antagonist L-701,324 might exert disease-modifying effects in fully kindled mice during a period with frequent seizure elicitation (massive kindling). Moreover, we analyzed whether L-701,324 exposure during this phase affects the subsequent response to an antiepileptic drug. L-701,324 treatment during the massive kindling phase did not affect ictogenesis. Mean seizure severity and cumulative seizure duration proved to be comparable between vehicle- and L-701,324-treated mice. Following withdrawal of L-701,324 seizure thresholds did not differ in a significant manner from those in animals that received vehicle injections. A low dosage of phenobarbital caused a significant increase of the generalized seizure threshold in the L-701,324 pre-treated group, whereas it did not exert a comparable effect in animals that received vehicle during the massive kindling phase. Analysis of P-glycoprotein in the hilus of the hippocampus revealed lower expression rates in L-701,324 pre-treated kindled mice. In conclusion, the data indicate that targeting of the NMDA receptor glycine-binding site does not result in anticonvulsant or disease-modifying effects. However, it might improve antiepileptic drug responses. The findings might be linked to an impact on P-glycoprotein expression. However, future studies are necessary to further evaluate the mechanisms and assess the potential of respective add-on approaches.

  15. Conessine, an H3 receptor antagonist, alters behavioral and neurochemical effects of ethanol in mice.

    Science.gov (United States)

    Morais-Silva, Gessynger; Ferreira-Santos, Mariane; Marin, Marcelo T

    2016-05-15

    Ethanol abuse potential is mainly due to its reinforcing properties, crucial in the transition from the recreational to pathological use. These properties are mediated by mesocorticolimbic and nigrostriatal dopaminergic pathways and neuroadaptations in these pathways seem to be responsible for addiction. Both pathways are modulated by other neurotransmitters systems, including neuronal histaminergic system. Among the histamine receptors, H3 receptor stands out due to its role in modulation of histamine and other neurotransmitters release. Thus, histaminergic system, through H3 receptors, may have an important role in ethanol addiction development. Aiming to understand these interactions, conessine, an H3 receptor antagonist, was given to mice subjected to the evaluation of ethanol-induced psychostimulation, ethanol CPP and quantification of norepinephrine, dopamine, serotonin and their metabolites in mesocorticolimbic and nigrostriatal pathways following acute ethanol treatment. Systemic conessine administration exacerbated ethanol effects on locomotor activity. Despite of conessine reinforcing effect on CPP, this drug did not alter acquisition of ethanol CPP. Ethanol treatment affects the serotoninergic neurotransmission in the ventral tegmental area, the dopaminergic neurotransmission in the pre-frontal cortex (PFC) and caudate-putamen nucleus (CPu) and the noradrenergic neurotransmission in the CPu. In the PFC, conessine blocked ethanol effects on dopaminergic and noradrenergic neurotransmission. The blockade of H3 receptors and ethanol seem to interact in the modulation of dopaminergic neurotransmission of nigrostriatal pathway, decreasing dopamine metabolites in substantia nigra. In conclusion, conessine was able to change psychostimulant effect of ethanol, without altering its reinforcing properties. This exacerbation of ethanol-induced psychostimulation would be related to alterations in dopaminergic neurotransmission in the nigrostriatal pathway.

  16. A Selective Nociceptin Receptor Antagonist to Treat Depression: Evidence from Preclinical and Clinical Studies.

    Science.gov (United States)

    Post, Anke; Smart, Trevor S; Krikke-Workel, Judith; Dawson, Gerard R; Harmer, Catherine J; Browning, Michael; Jackson, Kimberley; Kakar, Rishi; Mohs, Richard; Statnick, Michael; Wafford, Keith; McCarthy, Andrew; Barth, Vanessa; Witkin, Jeffrey M

    2016-06-01

    Nociceptin/Orphanin FQ (N/OFQ) is an endogenous ligand of the N/OFQ peptide (NOP) receptor, which is a G protein-coupled receptor in brain regions associated with mood disorders. We used a novel, potent, and selective orally bioavailable antagonist, LY2940094, to test the hypothesis that blockade of NOP receptors would induce antidepressant effects. In this study we demonstrate that targeting NOP receptors with LY2940094 translates to antidepressant-like effects in rodent models and, importantly, to antidepressant efficacy in patients with major depressive disorder (MDD). The proof-of-concept study (POC) was an 8-week, double-blind, placebo-controlled trial that evaluated LY2940094 as a novel oral medication for the treatment of patients with MDD. Once daily oral dosing of LY2940094 at 40 mg for 8 weeks vs placebo provided some evidence for an antidepressant effect based on the change from baseline to week 8 in the GRID-Hamilton Depression Rating Scale-17 item total score, although the predefined POC efficacy criterion (probability of LY2940094 being better than placebo⩾88%) was not met (82.9%). LY2940094 also had an early effect on the processing of emotional stimuli at Week 1 as shown by an increased recognition of positive relative to negative facial expressions in an emotional test battery. LY2940094 was safe and well tolerated. Overall, these are the first human data providing evidence that the blockade of NOP receptor signaling represents a promising strategy for the treatment of MDD.

  17. Crystal structure of the[mu]-opioid receptor bound to a morphinan antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Manglik, Aashish; Kruse, Andrew C.; Kobilka, Tong Sun; Thian, Foon Sun; Mathiesen, Jesper M.; Sunahara, Roger K.; Pardo, Leonardo; Weis, William I.; Kobilka, Brian K.; Granier, Sébastien (Michigan-Med); (Stanford-MED); (UAB, Spain)

    2012-06-27

    Opium is one of the world's oldest drugs, and its derivatives morphine and codeine are among the most used clinical drugs to relieve severe pain. These prototypical opioids produce analgesia as well as many undesirable side effects (sedation, apnoea and dependence) by binding to and activating the G-protein-coupled {mu}-opioid receptor ({mu}-OR) in the central nervous system. Here we describe the 2.8 {angstrom} crystal structure of the mouse {mu}-OR in complex with an irreversible morphinan antagonist. Compared to the buried binding pocket observed in most G-protein-coupled receptors published so far, the morphinan ligand binds deeply within a large solvent-exposed pocket. Of particular interest, the {mu}-OR crystallizes as a two-fold symmetrical dimer through a four-helix bundle motif formed by transmembrane segments 5 and 6. These high-resolution insights into opioid receptor structure will enable the application of structure-based approaches to develop better drugs for the management of pain and addiction.

  18. Use of prolactin receptor antagonist to better understand prolactin regulation of pituitary homeostasis.

    Science.gov (United States)

    Ferraris, Jimena; Bernichtein, Sophie; Pisera, Daniel; Goffin, Vincent

    2013-01-01

    The anterior pituitary is permanently regulated by processes of apoptosis and proliferation in order to maintain tissue homeostasis. Several factors have been implicated in this regulation and lately, prolactin (PRL) has been included into that list. However, since PRL is secreted by anterior pituitary lactotropes, the actual outcome of its autocrine/paracrine actions on pituitary cells has remained difficult to assess. The availability of the pure PRL receptor antagonist Del1-9-G129R-hPRL has been helpful to circumvent this problem. While PRL has been traditionally associated with increased cell proliferation, recent studies revealed that this hormone actually induces apoptosis and decreases proliferation of anterior pituitary cells, by mechanisms involving the PRL receptor. The aim of this short review is to overview our current understanding of the regulation of pituitary homeostasis by PRL. Moreover, studies involving Del1-9-G129R-hPRL have helped anticipate to what extent future treatments involving PRL receptor inhibitors may interfere with processes regulated by PRL at the central level. © 2013 S. Karger AG, Basel.

  19. Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium.

    LENUS (Irish Health Repository)

    Dooley, Ruth

    2012-02-01

    BACKGROUND: Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation. RESULTS: Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells. CONCLUSION: Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.

  20. Molecular determinants responsible for sedative and non-sedative properties of histamine H₁-receptor antagonists.

    Science.gov (United States)

    Uesawa, Yoshihiro; Hishinuma, Shigeru; Shoji, Masaru

    2014-01-01

    There is argument whether non-sedative properties of histamine H1-receptor antagonists (antihistamines) are determined by their active extrusions from the brain via P-glycoprotein or their restricted penetration through the blood-brain barrier. We have reported that sedative and non-sedative antihistamines can be well discriminated by measuring changes in their binding to H1 receptors upon receptor internalization in intact cells, which depends on their membrane-penetrating ability. In this study, molecular determinants responsible for sedative and non-sedative properties of antihistamines were evaluated by quantitative structure-activity relationship (QSAR) analyses. Multiple regression analyses were applied to construct a QSAR model, taking internalization-mediated changes in the binding of antihistamines as objective variables and their structural descriptors as explanatory variables. The multiple regression model was successfully constructed with two explanatory variables, i.e., lipophilicity of the compounds at physiological pH (logD) and mean information content on the distance degree equality (IDDE) (r(2) = 0.753). The constructed model discriminated between sedative and non-sedative antihistamines with 94% accuracy for external validation. These results suggest that logD and IDDE concerning lipophilicity and molecular shapes of compounds, respectively, predominantly determine the membrane-penetrating ability of antihistamines for their side effects on the central nervous system.

  1. Gene expression profiling of the androgen receptor antagonists flutamide and vinclozolin in zebrafish (Danio rerio) gonads

    Energy Technology Data Exchange (ETDEWEB)

    Martinovic-Weigelt, Dalma, E-mail: dalma@stthomas.edu [US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804 (United States); University of St. Thomas, 2115 Summit Ave, Saint Paul, MN 55105 (United States); Wang Ronglin [US Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Ecological Exposure Research Division, 26W. Martin Luther King Dr., Cincinnati, OH 45268 (United States); Villeneuve, Daniel L. [US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804 (United States); Bencic, David C.; Lazorchak, Jim [US Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Ecological Exposure Research Division, 26W. Martin Luther King Dr., Cincinnati, OH 45268 (United States); Ankley, Gerald T. [US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804 (United States)

    2011-01-25

    The studies presented in this manuscript focus on characterization of transcriptomic responses to anti-androgens in zebrafish (Danio rerio). Research on the effects of anti-androgens in fish has been characterized by a heavy reliance on apical endpoints, and molecular mechanisms of action (MOA) of anti-androgens remain poorly elucidated. In the present study, we examined effects of a short term exposure (24-96 h) to the androgen receptor antagonists flutamide (FLU) and vinclozolin (VZ) on gene expression in gonads of sexually mature zebrafish, using commercially available zebrafish oligonucleotide microarrays (4 x 44 K platform). We found that VZ and FLU potentially impact reproductive processes via multiple pathways related to steroidogenesis, spermatogenesis, and fertilization. Observed changes in gene expression often were shared by VZ and FLU, as demonstrated by overlap in differentially-expressed genes and enrichment of several common key pathways including: (1) integrin and actin signaling, (2) nuclear receptor 5A1 signaling, (3) fibroblast growth factor receptor signaling, (4) polyamine synthesis, and (5) androgen synthesis. This information should prove useful to elucidating specific mechanisms of reproductive effects of anti-androgens in fish, as well as developing biomarkers for this important class of endocrine-active chemicals.

  2. Therapy for acute pancreatitis with platelet-activating factor receptor antagonists

    Institute of Scientific and Technical Information of China (English)

    Chong Chen; Shi-Hai Xia; Hong Chen; Xiao-Hong Li

    2008-01-01

    Acute pancreatitis (AP) causes release of plateletactivating factor (PAF),which induces systemic effects that contribute to circulatory disturbances and multiple organ failure.PAF is a cell surface secretion of bioactive lipid,which could produce physiological and pathological effects by binding to its cell surface receptor called platelet-activating factor receptor (PAF-R).Studies showed that PAF participates in the occurrence and development of AP and administration of platelet-activating factor receptor antagonists (PAF-RAs) could significantly reduce local and systemic events after AP.PAF has also been implicated as a key mediator in the progression of severe AP,which can lead to complications and unacceptably high mortality rates.Several classes of PAF-RA show PAFRAs significant local and systemic effects on reducing inflammatory changes.As a preventive treatment,PAF-RA could block a series of PAF-mediatedinflammatory injury and thus improve the prognosis of AR This review introduces the important role of PAF-RA in the treatment of AP.

  3. High-throughput screening of novel antagonists on melanin-concentrat-ing hormone receptor-1

    Institute of Scientific and Technical Information of China (English)

    Jian-hua YAN; Qun-yi LI; Jean A BOUTIN; M Pierre RENARD; Yi-xiang DING; Xiao-jiang HAO; Wei-min ZHAO; Ming-wei WANG

    2008-01-01

    Aim: To find new antagonists on human melanin-concentrating hormone recep-tor- 1 (MCHR-1) through high-throughput screening (HTS) of a diverse com-pound library. Methods: MCHR-1, [3H]SNAP7941, and FlashBlue G-protein-coupled receptor beads were used to measure the receptor-binding activities of various compounds based on scintillation proximity assay (SPA) technology. The guanosine 5' (γ-[35S]thio) triphosphate ([35S]GTPγS) binding assay was sub-sequently applied to functionally characterize the "hits" identified by the HTS campaign. Results: Of the 48 240 compounds screened with the SPA method, 12 hits were confirmed to possess MCHR-1 binding activities, 8 were function-ally studied subsequently with the [35S]GTPγS binding assay, and only 1 com-pound (NC 127816) displayed moderate human MCHR- 1 binding affinity (Ki=115.7 nmol/L) and relatively potent antagonism (KB=23.8 nmol/L). This compound shares a novel scaffold (1-ethoxy-2H-2-aza-1-phospha-naphthalene 1-oxide) with 3 other analogs in the group. Conclusion: Considering the marked difference in molecular shape and electrostatic status between NC127816 and the structures reported elsewhere, we anticipate that its derivatives may repre-sent a new class of potent MCHR-1 modulators.

  4. Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium

    LENUS (Irish Health Repository)

    Dooley, Ruth

    2011-08-22

    Abstract Background Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation. Results Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells. Conclusion Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.

  5. Identification of VDR Antagonists among Nuclear Receptor Ligands Using Virtual Screening

    Directory of Open Access Journals (Sweden)

    Kelly Teske

    2014-04-01

    Full Text Available Herein, we described the development of two virtual screens to identify new vitamin D receptor (VDR antagonists among nuclear receptor (NR ligands. Therefore, a database of 14330 nuclear receptor ligands and their NR affinities was assembled using the online available “Binding Database.” Two different virtual screens were carried out in conjunction with a reported VDR crystal structure applying a stringent and less stringent pharmacophore model to filter docked NR ligand conformations. The pharmacophore models were based on the spatial orientation of the hydroxyl functionalities of VDR's natural ligands 1,25(OH2D3 and 25(OH2D3. The first virtual screen identified 32 NR ligands with a calculated free energy of VDR binding of more than -6.0 kJ/mol. All but nordihydroguaiaretic acid (NDGA are VDR ligands, which inhibited the interaction between VDR and coactivator peptide SRC2-3 with an IC50 value of 15.8 μM. The second screen identified 162 NR ligands with a calculated free energy of VDR binding of more than -6.0 kJ/mol. More than half of these ligands were developed to bind VDR followed by ERα/β ligands (26%, TRα/β ligands (7%, and LxRα/β ligands (7%. The binding between VDR and ERα ligand H6036 as well as TRα/β ligand triiodothyronine and a homoserine analog thereof was confirmed by fluorescence polarization.

  6. Pharmacologic Targets and Prototype Therapeutics in the Kallikrein-Kinin System: Bradykinin Receptor Agonists or Antagonists

    Directory of Open Access Journals (Sweden)

    J. N. Sharma

    2006-01-01

    Full Text Available The kallikrein-kinin system (KKS is a complex system produced in various organs. This system includes kininogen (precursor for kinin, kallikreins, and pharmacologically active bradykinin (BK, which is considered to be proinflammatory and/or cardioprotective. It is a proinflammatory polypeptide that is involved in many pathological conditions and can cause pain, inflammation, increased vascular permeability, vasodilation, contraction of various smooth muscles, as well as cell proliferation. On the other hand, it has been shown that BK has cardioprotective effects, as all components of KKS are located in the cardiac muscles. Numerous observations have indicated that decreased activity of this system may lead to cardiovascular diseases, such as hypertension, cardiac failure, and myocardial infarction. BK acts on two receptors, B1 and B2, which are linked physiologically through their natural stimuli and their common participation in a variety of inflammatory responses. Recently, numerous BK antagonists have been developed in order to treat several diseases that are due to excessive BK formation. Although BK has many beneficial effects, it has been recognized to have some undesirable effects that can be reversed with BK antagonists. In addition, products of this system have multiple interactions with other important metabolic pathways, such as the renin-angiotensin system.

  7. Pyrazole antagonists of the CB1 receptor with reduced brain penetration.

    Science.gov (United States)

    Fulp, Alan; Zhang, Yanan; Bortoff, Katherine; Seltzman, Herbert; Snyder, Rodney; Wiethe, Robert; Amato, George; Maitra, Rangan

    2016-03-01

    Type 1 cannabinoid receptor (CB1) antagonists might be useful for treating obesity, liver disease, metabolic syndrome, and dyslipidemias. Unfortunately, inhibition of CB1 in the central nervous system (CNS) produces adverse effects, including depression, anxiety and suicidal ideation in some patients, which led to withdrawal of the pyrazole inverse agonist rimonabant (SR141716A) from European markets. Efforts are underway to produce peripherally selective CB1 antagonists to circumvent CNS-associated adverse effects. In this study, novel analogs of rimonabant (1) were explored in which the 1-aminopiperidine group was switched to a 4-aminopiperidine, attached at the 4-amino position (5). The piperidine nitrogen was functionalized with carbamates, amides, and sulfonamides, providing compounds that are potent inverse agonists of hCB1 with good selectivity for hCB1 over hCB2. Select compounds were further studied using in vitro models of brain penetration, oral absorption and metabolic stability. Several compounds were identified with predicted minimal brain penetration and good metabolic stability. In vivo pharmacokinetic testing revealed that inverse agonist 8c is orally bioavailable and has vastly reduced brain penetration compared to rimonabant.

  8. A Combined Quantitative Structure-Activity Relationship Research of Quinolinone Derivatives as Androgen Receptor Antagonists.

    Science.gov (United States)

    Wang, Yuwei; Bai, Fang; Cao, Hong; Li, Jiazhong; Liu, Huanxiang; Gramatica, Paola

    2015-01-01

    Antiandrogens bicalutamide, flutamide and enzalutamide etc. have been used in clinical trials to treat prostate cancer by binding to and antagonizing androgen receptor (AR). Although initially effective, the drug resistance problem will emerge eventually, which results in a high medical need for novel AR antagonist exploitation. Here in this work, to facilitate the rational design of novel AR antagonists, we studied the structure-activity relationships of a series of 2-quinolinone derivatives and investigated the structural requirements for their antiandrogenic activities. Different modeling methods, including 2D MLR, 3D CoMFA and CoMSIA, were implemented to evolve QSAR models. All these models, thoroughly validated, demonstrated satisfactory results especially for the good predictive abilities. The contour maps from 3D CoMFA and CoMSIA models provide visualized explanation of key structural characteristics relevant to the antiandrogenic activities, which is summarized to a position-specific conclusion at the end. The obtained results from this research are practically useful for rational design and screening of promising chemicals with high antiandrogenic activities.

  9. Histamine and histamine type-2 receptor antagonists in psoriasis. Mechanisms and speculations

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen

    1991-01-01

    The findings that the immunosuppressant cyclosporine A (CsA) improves psoriasis raise the possibility that cellular immune processes may play a major role in the pathogenesis of this disease. It is broadly agreed that histamine released by mast cells is one of the molecules involved...... in the pathogenesis. This is supported by the findings that CsA and methotrexate (Mxt) reduce formation and release of histamine. However, the well known side-effects of CsA and Mxt may argue potential use of other agents acting on formation and action of histamine. Such agents may be the histamine-2 receptor...... antagonists, previously reported to have a clinical effect on psoriasis. But randomised short-term studies have disclosed that these drugs have no beneficial or even an aggravating effect on the disease. This article reports on recent findings of improvement in psoriasis using high doses of the histamine-2...

  10. The crystal structure of a bimorphinan with highly selective kappa opioid receptor antagonist activity

    Science.gov (United States)

    Urbańczyk-Lipkowska, Zofia; Etter, Margaret C.; Lipkowski, Andrzej W.; Portoghese, Philip S.

    1987-07-01

    The crystal structure of the dihydrobromide heptahydrate of nor-binaltorphimine (17, 17'-bis(cyclopropylmethyl)-6,6',7,7'-tetrahydro-4,5α: 4',5'α-diepoxy-6,6'-imino[7,7' bimorphinan]-3,3',14,14'-tetraol)is presented. This structure is the first reported structure of a rigid bivalent opioid ligand. Two morphinan pharmacophores are connected by a rigid spacer, the pyrrole ring. The nor-binaltorphimine structure itself shows unique, high selectivity as a kappa opioid receptor antagonist. Crystal data: P3 2, Z = 3, a = b = 20.223 (4), c = 9.541(7) Å, α = β = 90°, γ = 120°; R = 0.079 (1765 reflections, Fobs > 1σ( F)).

  11. Kinin Receptor Antagonists as Potential Neuroprotective Agents in Central Nervous System Injury

    Directory of Open Access Journals (Sweden)

    Anna V Leonard

    2010-09-01

    Full Text Available Injury to the central nervous system initiates complex physiological, cellular and molecular processes that can result in neuronal cell death. Of interest to this review is the activation of the kinin family of neuropeptides, in particular bradykinin and substance P. These neuropeptides are known to have a potent pro-inflammatory role and can initiate neurogenic inflammation resulting in vasodilation, plasma extravasation and the subsequent development of edema. As inflammation and edema play an integral role in the progressive secondary injury that causes neurological deficits, this review critically examines kinin receptor antagonists as a potential neuroprotective intervention for acute brain injury, and more specifically, traumatic brain and spinal cord injury and stroke.

  12. 4-(Phenylsulfonyl)piperidines: novel, selective, and bioavailable 5-HT(2A) receptor antagonists.

    Science.gov (United States)

    Fletcher, Stephen R; Burkamp, Frank; Blurton, Peter; Cheng, Susan K F; Clarkson, Robert; O'Connor, Desmond; Spinks, Daniel; Tudge, Matthew; van Niel, Monique B; Patel, Smita; Chapman, Kerry; Marwood, Rose; Shepheard, Sara; Bentley, Graham; Cook, Gina P; Bristow, Linda J; Castro, Jose L; Hutson, Peter H; MacLeod, Angus M

    2002-01-17

    On the basis of a spirocyclic ether screening lead, a series of acyclic sulfones have been identified as high-affinity, selective 5-HT(2A) receptor antagonists. Bioavailability lacking in the parent, 1-(2-(2,4-difluorophenyl)ethyl)-4-(phenylsulfonyl)piperidine (12), was introduced by using stability toward rat liver microsomes as a predictor of bioavailability. By this means, the 4-cyano- and 4-carboxamidophenylsulfonyl derivatives 26 and 31 were identified as orally bioavailable, brain-penetrant analogues suitable for evaluation in animal models. Bioavailability was also attainable by N substitution leading to the N-phenacyl derivative 35. IKr activity detected through counterscreening was reduced to insignificant levels in vivo with the latter compound.

  13. Fesoterodine: a novel muscarinic receptor antagonist for the treatment of overactive bladder syndrome.

    Science.gov (United States)

    Michel, Martin C

    2008-07-01

    Fesoterodine is a newly approved drug for the treatment of overactive bladder syndrome. The aim of this study was to review the preclinical and clinical data on fesoterodine. The study involved a search of the Medline database and the proceedings volumes of urological congresses. Fesoterodine functions as an orally active prodrug that is converted to the active metabolite 5-hydroxymethyltolterodine by non-specific esterases. 5-Hydroxymethyltolterodine is a muscarinic receptor antagonist. Fesoterodine is primarily eliminated as inactive metabolites along with significant renal excretion as the unchanged active metabolite 5-hydroxymethyltolterodine. Fesoterodine is indicated for use at doses of 4 and 8 mg once daily. In clinical studies both doses of fesoterodine were consistently superior to placebo in improving the symptoms of overactive bladder syndrome, with 8 mg/day having significantly greater effects than 4 mg/day.

  14. Interleukin-1B and Interleukin-1 Receptor Antagonist in Patients with Helicobacter pylori Associated Diseases

    Directory of Open Access Journals (Sweden)

    Elizaveta S. Ageeva, PhD

    2012-06-01

    Full Text Available The ethnic people of the Republic of Khakassia (the Khakas with ulcer disease show a significant T-cell activation and humoral immune response when compared with the Europoids. The reasons for such differences could be due to certain ethno-specific allelic variants of the interleukins, which considerably change the degree of cytokine expression. The aim was to study the peculiarities of the association of the interleukin-1 (IL-1 gene polymorphisms and interleukin-1 receptor antagonist (IL-1Ra. Patients with chronic gastritis and ulcer disease were examined using the restriction analysis method. The most wide-spread allelic variants among the Khakas were discovered to be С�� IL-1β and R4R4 IL-1Ra. In this study, we suggest the necessity to define the population’s risk and the protective genotypes that promote Helicobacter pylori-associated ulcer disease among the Khakas people.

  15. Novel multimeric IL-1 receptor antagonist for the treatment of rheumatoid arthritis.

    Science.gov (United States)

    Pasi, Shweta; Kant, Ravi; Gupta, Sarika; Surolia, Avadhesha

    2015-02-01

    Protein therapeutics targeting inflammatory mediators have shown great promise for the treatment of autoimmunities such as rheumatoid arthritis (RA). However, a significant challenge in this area has been their low in vivo stability and consequently their severely compromised therapeutic efficacy. One such therapeutic molecule IL-1 receptor antagonist (IL-1ra), used in the treatment of rheumatoid arthritis, has displayed only modest efficacy in human clinical trials owing to its short biological half-life. Herein, we report a novel approach to conglomerate individual protein entities into a drug depot by incorporation of an amyloidogenic motif Lys-Phe-Phe-Glu (KFFE) thereby dramatically improving their systemic persistence and in turn their therapeutic efficacy in a mice model of autoimmune arthritis.

  16. Evaluation of growth hormone (GH) action in mice: discovery of GH receptor antagonists and clinical indications.

    Science.gov (United States)

    Kopchick, John J; List, Edward O; Kelder, Bruce; Gosney, Elahu S; Berryman, Darlene E

    2014-04-05

    The discovery of a growth hormone receptor antagonist (GHA) was initially established via expression of mutated GH genes in transgenic mice. Following this discovery, development of the compound resulted in a drug termed pegvisomant, which has been approved for use in patients with acromegaly. Pegvisomant treatment in a dose dependent manner results in normalization of IGF-1 levels in most patients. Thus, it is a very efficacious and safe drug. Since the GH/IGF-1 axis has been implicated in the progression of several types of cancers, many have suggested the use of pegvisomant as an anti-cancer therapeutic. In this manuscript, we will review the use of mouse strains that possess elevated or depressed levels of GH action for unraveling many of GH actions. Additionally, we will describe experiments in which the GHA was discovered, review results of pegvisomant's preclinical and clinical trials, and provide data suggesting pegvisomant's therapeutic value in selected types of cancer.

  17. Lack of Association between an Interleukin-I Receptor Antagonist Gene Polymorphism and Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Victor A. Danis

    1994-01-01

    Full Text Available Non-MHC linked genes may contribute to genetic predisposition to the development of systemic lupus erythematosus. The possibility that cytokine genes may be involved was raised by the observation of increased frequency in expression of an uncommon allele of an interleukin-I receptor antagonist gene polymorphism and SLE in a recent U.K. study. We have not been able to show any significant differences in expression of this allele in SLE patients as a whole or in any patient subgroups. Our results actually show a slight decrease in the expression of this allele in SLE patients compared with healthy controls and in SLE patients with malar rash compared with SLE patients without malar rash.

  18. [Use of maraviroc, the first CCR5 receptor antagonist, in HIV treatment regimens].

    Science.gov (United States)

    Kravchenko, A V

    2013-01-01

    The paper gives the results of international trials of and guidelines for the use of maraviroc, the first CCR5 receptor antagonist, in treatment regimens for HIV-infected patients. The trials have convincingly shown that the maraviroc-containing antiretroviral therapy (ART) regimens are highly effective and safe for R5-tropic HIV-infected patients regardless of previous ART, baseline HIV RNA levels, and CD4+ lymphocyte count. Maraviroc can be recommended for HIV-infected patients who have previously received ART and who have been found to have a R5-tropic virus. The changes in the ART regimen and inclusion of maraviroc may be associated with both an ineffective previous treatment regimen and therapy-induced adverse events. In 2012, Russia's first reagent kit for the determination of HIV tropism was put to tests and registered at the Russian Inspectorate for the Protection of Consumer Rights and Human Welfare.

  19. New H2-receptor antagonist--roxatidine acetate--in treatment of duodenal ulcer.

    Science.gov (United States)

    Amarapurkar, D N; Parikh, S S; Desai, H G

    1993-08-01

    A double blind randomised trial, comparing a new H2-receptor antagonist, Roxatidine acetate, with Cimetidine was carried out in 47 patients of uncomplicated, endoscopically proven duodenal ulcer. Twenty seven patients were treated with Roxatidine 75 mg twice daily and 20 patients were treated with Cimetidine 200 mg 3 times a day and 400 mg at bed time for 4 weeks. At the end of 4 weeks, total pain relief was obtained in 74% and 70% patients receiving Roxatidine and Cimetidine respectively. Complete endoscopic healing at the end of 4 weeks was observed in 92.3% patients receiving Roxatidine and 85% patients receiving Cimetidine. These differences were statistically not significant. No significant side effects were observed in either group. We conclude that Roxatidine acetate is comparable to cimetidine in relieving pain and endoscopic healing of duodenal ulcer and has an excellent safety profile.

  20. GABAB Receptor Antagonist CGP46381 Inhibits Form-Deprivation Myopia Development in Guinea Pigs

    Directory of Open Access Journals (Sweden)

    Zhen-Ying Cheng

    2015-01-01

    Full Text Available The aim was to investigate the effects of the GABAB receptor antagonist, CGP46381, on form-deprivation myopia (FDM in guinea pigs. Twenty-four guinea pigs had monocular visual deprivation induced using a diffuser for 11 days (day 14 to 25. The deprived eyes were treated with daily subconjunctival injections (100 μl of either 2% CGP46381, 0.2% CGP46381, or saline or received no injection. The fellow eyes were left untreated. Another six animals received no treatment. At the start and end of the treatment period, ocular refractions were measured using retinoscopy and vitreous chamber depth (VCD and axial length (AL using A-scan ultrasound. All of the deprived eyes developed relative myopia (treated versus untreated eyes, P0.05. Subconjunctival injections of CGP46381 inhibit FDM development in guinea pigs in a dose-dependent manner.

  1. Endothelin Receptor Antagonists for the Treatment of Raynaud's Phenomenon and Digital Ulcers in Systemic Sclerosis

    Directory of Open Access Journals (Sweden)

    Kait Arefiev

    2011-01-01

    Full Text Available Systemic sclerosis is a connective tissue disease characterized by fibrosis of the skin, internal organs, and widespread vasculopathy. Raynaud's phenomenon and digital ulcers are vascular manifestations of this disease and cause significant morbidity. Current treatments are only moderately effective in reducing the severity of Raynaud's in a portion of patients and typically do not lead to substantial benefit in terms of the healing or prevention of digital ulcers. Several studies have evaluated the efficacy of targeting the vasoconstrictor endothelin-1 for the treatment of systemic sclerosis-associated vascular disease. The purpose of this paper is to summarize the published studies and case reports evaluating the efficacy of endothelin receptor antagonists in the treatment of Raynaud's phenomenon and digital ulcers associated with systemic sclerosis.

  2. Asymmetric synthesis of telcagepant, a CGRP receptor antagonist for the treatment of migraine.

    Science.gov (United States)

    Xu, Feng; Zacuto, Michael; Yoshikawa, Naoki; Desmond, Richard; Hoerrner, Scott; Itoh, Tetsuji; Journet, Michel; Humphrey, Guy R; Cowden, Cameron; Strotman, Neil; Devine, Paul

    2010-11-19

    A highly efficient, asymmetric synthesis of telcagepant (1), a CGRP receptor antagonist for the treatment of migraine, is described. This synthesis features the first application of iminium organocatalysis on an industrial scale. The key to the success of this organocatalytic transformation was the identification of a dual acid cocatalyst system, which allowed striking a balance of the reaction efficiency and product stability effectively. As such, via an iminium species, the necessnary C-6 stereogenicity was practically established in one operation in >95% ee. Furthermore, we enlisted an unprecedented Doebner-Knoevenagel coupling, which was also via an iminium species, to efficiently construct the C3-C4 bond with desired functionality. In order to prepare telcagepant (1) in high quality, a practical new protocol was discovered to suppress the formation of desfluoro impurities formed under hydrogenation conditions to manufacturing process and prepares telcagepant (1) with the high quality required for pharmaceutical use.

  3. Differential involvement of the opioid receptor antagonist naloxone in motivational and hedonic aspects of reward.

    Science.gov (United States)

    Schneider, Miriam; Heise, Verena; Spanagel, Rainer

    2010-04-02

    In the present study dose-dependent effects of the opioid receptor antagonist naloxone were investigated on the rewarding effects of sweetened condensed milk (SCM) in four behavioral paradigms addressing hedonic, consummatory as well as motivational aspects of a reward: odour-conditioned pleasure attenuation of the acoustic startle response (PAS), conditioned place preference (CPP), voluntary consumption in a limited access paradigm, as well as break point determination in a progressive ratio (PR) task. A dose-dependent reduction in reward-related behavior was observed in all paradigms, with exception of the break point in the PR task, which was not affected by naloxone at all. CPP for SCM was only affected by the highest dose of naloxone. The present results indicate that naloxone is more effective in suppressing the hedonic than motivational aspects of reward, further supporting the involvement of the endogenous opioid system in the mediation of hedonic properties of food reward.

  4. Ibuprofen protects ischemia-induced neuronal injury via up-regulating interleukin-1 receptor antagonist expression.

    Science.gov (United States)

    Park, E-M; Cho, B-P; Volpe, B T; Cruz, M O; Joh, T H; Cho, S

    2005-01-01

    The inflammatory response accompanies and exacerbates the developing injury after cerebral ischemia. Ibuprofen, a non-steroidal anti-inflammatory drug, has been shown to attenuate injuries in animal models of various neurological diseases. In the present study, we investigated ibuprofen's neuroprotective effects in rats exposed to transient forebrain ischemia and in cultures exposed to oxygen glucose deprivation (OGD). Rats treated with ibuprofen after transient forebrain ischemia displayed long-lasting protection of CA1 hippocampal neurons. There were selective increases in interleukin-1 receptor antagonist gene and protein expression in ibuprofen-treated OGD microglia. Furthermore, treatment with ibuprofen in neuron/microglia co-cultures increased the number of surviving HC2S2 neurons against OGD whereas IL-1ra neutralizing antibody reversed the ibuprofen-induced neuroprotection. The data indicate that ibuprofen-induced IL-1ra secretion is involved in neuroprotection against ischemic conditions.

  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...... in the rat. Spinal microdialysis was used to measure in vivo changes of acetylcholine after administration of the ligands, with or without nicotinic receptor blockade. In addition, in vitro binding properties of the ligands on muscarinic and nicotinic receptors were investigated. It was found that clonidine...

  6. Design and synthesis of labeled analogs of PhTX-56, a potent and selective AMPA receptor antagonist

    DEFF Research Database (Denmark)

    Andersen, Trine F; Vogensen, Stine B; Jensen, Lars S

    2005-01-01

    antagonist of Ca2+-permeable AMPA receptors. PhTX-56 and its labeled derivatives are promising tools for structure-function studies of the ion channel of the AMPA receptor. We now describe the design and synthesis of 3H-, 13C-, and 15N-labeled derivatives of PhTX-56 for molecular level studies of AMPA....... These analogs can provide detailed information on the ligand-receptor interaction. In conclusion, synthesis of labeled derivatives of PhTX-56 provides important tools for future studies of the pore-forming region of AMPA receptors....

  7. Cannabinoid receptor-2 selective antagonist negatively regulates receptor activator of nuclear factor kappa B ligand mediated osteoclastogenesis

    Institute of Scientific and Technical Information of China (English)

    GENG De-chun; XU Yao-zeng; YANG Hui-lin; ZHU Guang-ming; WANG Xian-bin; ZHU Xue-song

    2011-01-01

    Background The cannabinoid receptor-2 (CB2) is important for bone remodeling. In this study, we investigated the effects of CB2 selective antagonist (AM630) on receptor activator of nuclear factor kappa B (RANK) ligand (RANKL)induced osteoclast differentiation and the underlying signaling pathway using a monocyte-macrophage cell line-RAW264.7.Methods RAW264.7 was cultured with RANKL for 6 days and then treated with AM630 for 24 hours. Mature osteoclasts were measured by tartrate-resistant acid phosphatase (TRAP) staining using a commercial kit. Total ribonucleic acid (RNA)was isolated and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was done to examine the expression of RANK, cathepsin K (CPK) and nuclear factor kappa B (NF-κB). The extracellular signal-regulated kinase (ERK),phosphorylation of ERK (P-ERK) and NF-κB production were tested by Western blotting. The effect of AM630 on RAW264.7 viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay.Results AM630 did not affect the viability of RAW264.7. However, this CB2 selective antagonist markedly inhibited osteoclast formation and the inhibition rate was dose-dependent. The dose of >100 nmol/L could reduce TRAP positive cells to the levels that were significantly lower than the control. AM630 suppressed the expression of genes associated with osteoclast differentiation and activation, such as RANK and CPK. An analysis of a signaling pathway showed that AM630 inhibited the RANKL-induced activation of ERK, but not NF-κB.Conclusion AM630 could inhibit the osteoclastogenesis from RAW264.7 induced with RANKL.

  8. Pharmacology of modality-specific transient receptor potential vanilloid-1 antagonists that do not alter body temperature.

    Science.gov (United States)

    Reilly, Regina M; McDonald, Heath A; Puttfarcken, Pamela S; Joshi, Shailen K; Lewis, LaGeisha; Pai, Madhavi; Franklin, Pamela H; Segreti, Jason A; Neelands, Torben R; Han, Ping; Chen, Jun; Mantyh, Patrick W; Ghilardi, Joseph R; Turner, Teresa M; Voight, Eric A; Daanen, Jerome F; Schmidt, Robert G; Gomtsyan, Arthur; Kort, Michael E; Faltynek, Connie R; Kym, Philip R

    2012-08-01

    The transient receptor potential vanilloid-1 (TRPV1) channel is involved in the development and maintenance of pain and participates in the regulation of temperature. The channel is activated by diverse agents, including capsaicin, noxious heat (≥ 43°C), acidic pH (temperature antagonists representing multiple TRPV1 pharmacophores were evaluated at recombinant rat and human TRPV1 channels with Ca(2+) flux assays, and two classes of antagonists were identified based on their differential ability to inhibit acid activation. Although both classes of antagonists completely blocked capsaicin- and NADA-induced activation of TRPV1, select compounds only partially inhibited activation of the channel by protons. Electrophysiology and calcitonin gene-related peptide release studies confirmed the differential pharmacology of these antagonists at native TRPV1 channels in the rat. Comparison of the in vitro pharmacological properties of these TRPV1 antagonists with their in vivo effects on core body temperature confirms and expands earlier observations that acid-sparing TRPV1 antagonists do not significantly increase core body temperature. Although both classes of compounds elicit equivalent analgesia in a rat model of knee joint pain, the acid-sparing antagonist tested is not effective in a mouse model of bone cancer pain.

  9. Screening for cardiovascular safety: a structure-activity approach for guiding lead selection of melanin concentrating hormone receptor 1 antagonists.

    Science.gov (United States)

    Kym, Philip R; Souers, Andrew J; Campbell, Thomas J; Lynch, John K; Judd, Andrew S; Iyengar, Rajesh; Vasudevan, Anil; Gao, Ju; Freeman, Jennifer C; Wodka, Dariusz; Mulhern, Mathew; Zhao, Gang; Wagaw, Seble H; Napier, James J; Brodjian, Sevan; Dayton, Brian D; Reilly, Regina M; Segreti, Jason A; Fryer, Ryan M; Preusser, Lee C; Reinhart, Glenn A; Hernandez, Lisa; Marsh, Kennan C; Sham, Hing L; Collins, Christine A; Polakowski, James S

    2006-04-06

    An inactin-anesthetized rat cardiovascular (CV) assay was employed in a screening mode to triage multiple classes of melanin-concentrating hormone receptor 1 (MCHr1) antagonists. Lead identification was based on a compound profile producing high drug concentration in both plasma (>40 microM) and brain (>20 microg/g) with optimization activities on multiple classes of MCHr1 antagonists were terminated. After providing evidence that the cardiovascular liabilities were not a function of MCHr1 antagonism, continued screening identified the chromone-substituted aminopiperidine amides as a class of MCHr1 antagonists that demonstrated a safe cardiovascular profile at high drug concentrations in both plasma and brain. The high incidence of adverse cardiovascular effects associated with an array of MCHr1 antagonists of significant chemical diversity, combined with the stringent safety requirements for antiobesity drugs, highlight the importance of incorporating cardiovascular safety assessment early in the lead selection process.

  10. Mineralocorticoid receptor antagonists in heart failure with preserved ejection fraction (HFpEF).

    Science.gov (United States)

    Capuano, Annalisa; Scavone, Cristina; Vitale, Cristiana; Sportiello, Liberata; Rossi, Francesco; Rosano, Giuseppe M C; Coats, Andrew J Stewart

    2015-12-01

    The role of spironolactone and eplerenone in patients with Heart Failure with preserved Ejection Fraction (HFpEF) is not well defined. Since a growing medical literature has suggested that mineralocorticoid receptor antagonists may be beneficial for patients with HFpEF, this review gives an in-depth update on the role of spironolactone and eplerenone and their implications for therapy in the setting of HFpEF. Eleven clinical studies, including seven randomized trials, were reviewed. Two randomized controlled trials evaluated the effect of eplerenone on different end-points, including 6 minute walk distance (6 MWD), cardiovascular mortality, non-fatal reinfarction, hospitalization for unstable angina and congestive heart failure. Eplerenone did not affect either 6 MWD or event-free survival rates in the overall study population in these two reports. The effects of spironolactone on similar composite endpoints were evaluated in 7 studies in patients with HFpEF. Compared to placebo, hospitalization for heart failure was significantly lower in the spironolactone group and spironolactone was also shown to improve diastolic function and induced beneficial remodeling through a reduction in myocardial fibrosis. The safety profile of spironolactone and eplerenone has been assessed in two recent studies. Data showed that eplerenone and spironolactone are both associated with the occurrence of gynecomastia, mastodynia, and abnormal vaginal bleeding and in addition, they can increase natriuresis and cause renal retention of potassium; furthermore, eplerenone may cause hyperkalemia and promote the onset of metabolic acidosis or hyponatremia. In conclusion although the mineralocorticoid receptor antagonists eplerenone and spironolactone improve clinical outcomes in patients with HFrEF, additional data will be necessary to better define their risk-benefit profile, especially for eplerenone, in the treatment of HFpEF.

  11. Endothelin receptor antagonist attenuates inflammatory response and prolongs the survival time in a neonatal sepsis model.

    Science.gov (United States)

    Goto, Tatenobu; Hussein, Mohamed Hamed; Kato, Shin; Daoud, Ghada Abdel-Hamid; Kato, Takenori; Kakita, Hiroki; Mizuno, Haruo; Imai, Masaki; Ito, Tetsuya; Kato, Ineko; Suzuki, Satoshi; Okada, Noriko; Togari, Hajime; Okada, Hidechika

    2010-12-01

    To evaluate effects of endothelin receptor antagonist ETR-P1/fl in a neonatal sepsis model. Eighteen anesthetized and mechanically ventilated 3-day-old piglets were divided into three groups. Six piglets received cecal ligation and perforation (CLP group). Six piglets were administrated a continuous infusion of ETR-P1/fl (0.05 mg/kg/h), an antisense homology box-derived peptide with an endothelin A receptor antagonist effect, starting 30 min after CLP (ETR-P1/fl group). Six piglets acted as the sham group. Mean arterial pressure (MAP), heart rate, cardiac output, arterial blood gas, body temp (BT), serum nitrite and nitrate (NOx), tumor necrosis factor (TNF)-α, and high-mobility group box 1 (HMGB-1) were measured before CLP and at 1, 3, 6, and 9 h after CLP. Cecal ligation and perforation exposure evoked a state of shock and showed deteriorated cardiac output, pulmonary hypertension, decreased MAP, low oxygen saturation, and base excess (BE) with elevated TNF-α, NOx, and HMGB1. ETR-P1/fl administration resulted in higher MAP at 6 and 9 h after CLP, less negative BE, lower mean pulmonary arterial pressure (mPAP)/MAP ratio at 9 h after CLP, and lower TNF-α, NOx, and HMGB-1 compared to the CLP group. BT showed no differences between the groups. Survival time in the ETR-P1/fl group was longer than in the CLP group (18.9 ± 2.3 h vs. 9.0 ± 0.8 h, p model.

  12. Polymorphisms of interleukin-1R receptor antagonist genes in patients with chronic hepatitis B in Iran

    Institute of Scientific and Technical Information of China (English)

    Mitra Ranjbar; Amir Houshang Mohammad Alizadeh; Mehrdad Hajiloi; Seyed Mohsen Mousavi

    2006-01-01

    AIM: To investigate the relationships between polymorphisms of interleukin-1R receptor antagonist genes and susceptibility to chronic hepatitis B in Iran population.METHODS: Genomic DNA was extracted from the peripheral blood of 80 patients with chronic hepatitis B (57 males, 23 females) aged 12-77 years (mean 36.1± 13.8 years) and 147 normal controls (96 males, 51females) aged 6-75 years (mean 41±18.7 years) who referred to a liver clinic of Tehran and then subjected to polymerase chain reaction (PCR) amplification. PCR products were resolved on a 3% agarose gel and stained with ethidium bromide.RESULTS: Only three of the five kinds of polymorphism (2/2, 2/4, and 4/4) were found in this study. The frequencies of 2/2, 2/4, and 4/4 were 12.5%, 17.5%,70% respectively in chronic hepatitis B patients and 6.8%,24.5%, and 68.7% respectively in controls. IL-1 R allele 2 was detected in 30% of chronic hepatitis B patients and in 31.3% of controls, while IL-1 R allele 4 was detected in 87.5% of chronic hepatitis B patients and in 93.2% of controls. The frequency of IL-1R alleles 2 and 4 was detected in 21.25% and 78.75% of the patients and 19.04% and 80.96% of the controls, respectively.CONCLUSION: Our results suggest that the carriage of IL-1R receptor antagonist alleles 2, 4, 6 may not play any role in the development of HBV infection. Large population-based studies are needed to investigate the role of IL-1 polymorphisms in the pathogenesis of developing chronic hepatitis B.

  13. Formulation development for the orexin receptor antagonist almorexant: assessment in two clinical studies

    Directory of Open Access Journals (Sweden)

    Dingemanse J

    2014-04-01

    Full Text Available Jasper Dingemanse, Martine Gehin, Hans Gabriel Cruz, Petra HoeverDepartment of Clinical Pharmacology, Actelion Pharmaceuticals Ltd, Allschwil, SwitzerlandAbstract: Almorexant, a dual orexin receptor antagonist, was investigated for the treatment of insomnia. The following observations initiated further formulation development: the active pharmaceutical ingredient (API was sticking to the apparatus used during tablet compression; almorexant has an absolute bioavailability of 11.2%; and almorexant modestly decreased the latency to persistent sleep by 10.4 minutes in patients. Two randomized crossover studies were performed to investigate the pharmacokinetics of several new formulations in healthy subjects. In study I, the old “sticky” tablet was compared to two new formulations developed to prevent sticking: a qualitatively similar tablet but with a larger API crystal size and a tablet with 30% more excipients as well as a larger API crystal size. This latter formulation was available in two strengths. The geometric mean ratios and 90% confidence interval of the area under the curve (AUC were within the bioequivalence range of 0.80–1.25 for the different comparisons between formulations. In study II, 100 mg of the reference tablet was compared to 25 and 50 mg of a liquid-filled hard gelatin capsule developed to increase the bioavailability of almorexant. The geometric mean ratios of the maximum concentration and AUC comparing the new 25 and 50 mg capsule formulations to the reference tablet did not exceed 0.25 and 0.50, respectively, indicating that the new capsule formulation did not increase the maximum concentration of or the total exposure to almorexant. In conclusion, a new tablet was developed but formulation development aimed at increasing the bioavailability of almorexant failed.Keywords: almorexant, orexin receptor antagonist, pharmacokinetics, formulation development, healthy subjects

  14. Mechanisms for Antagonistic Regulation of AMPA and NMDA-D1 Receptor Complexes at Postsynaptic Sites

    Science.gov (United States)

    Schumann, Johann; Scheler, Gabriele

    2004-01-01

    From the analysis of these pathways we conclude that postsynaptic processes that regulate synaptic transmission undergo significant cross-talk with respect to glutamatergic and neuromodulatory (dopamine) signals. The main hypothesis is that of a compensatory regulation, a competitive switch between the induction of increased AMPA conductance by CaMKII-dependent phosphorylation and reduced expression of PP2A, and increased D1 receptor sensitivity and expression by increased PKA, PP2A and decreased PP-1/calcineurin expression. Both types of plasticity are induced by NMDA receptor activation and increased internal calcium, they require different internal conditions to become expressed. Specifically we propose that AMPA regulation and D1 regulation are inversely coupled;The net result may be a bifurcation of synaptic state into predominantly AMPA or NMDA-D1 synapses. This could have functional consequences: stable connections for AMPA and conditional gating for NMDA-D1 synapses.

  15. 1-Sulfonyl-6-Piperazinyl-7-Azaindoles as potent and pseudo-selective 5-HT6 receptor antagonists.

    Science.gov (United States)

    Fabritius, Charles-Henry; Pesonen, Ullamari; Messinger, Josef; Horvath, Raymond; Salo, Harri; Gałęzowski, Michał; Galek, Mariusz; Stefańska, Klaudia; Szeremeta-Spisak, Joanna; Olszak-Płachta, Marta; Buda, Anna; Adamczyk, Justyna; Król, Marcin; Prusis, Peteris; Sieprawska-Lupa, Magdalena; Mikulski, Maciej; Kuokkanen, Katja; Chapman, Hugh; Obuchowicz, Radosław; Korjamo, Timo; Jalava, Niina; Nowak, Mateusz

    2016-06-01

    A series of 1-Sulfonyl-6-Piperazinyl-7-Azaindoles, showing strong antagonistic activity to 5-HT6 receptor (5-HT6R) was synthesized and characterized. The series was optimized to reduce activity on D2 receptor. Based on the selectivity against this off-target and the analysis of the ADME-tox profile, compound 1c was selected for in vivo efficacy assessment, which demonstrated procognitive effects as shown in reversal of scopolamine induced amnesia in an elevated plus maze test in mice. Compound 3, the demethylated version of compound 1c, was profiled against a panel of 106 receptors, channels and transporters, indicating only D3 receptor as a major off-target. Compound 3 has been selected for this study over compound 1c because of the higher 5-HT6R/D2R binding ratio. These results have defined a new direction for the design of our pseudo-selective 5-HT6R antagonists.

  16. Identification of Putative Steroid Receptor Antagonists in Bottled Water: Combining Bioassays and High-Resolution Mass Spectrometry

    Science.gov (United States)

    Wagner, Martin; Schlüsener, Michael P.; Ternes, Thomas A.; Oehlmann, Jörg

    2013-01-01

    Endocrine disrupting chemicals (EDCs) are man-made compounds interfering with hormone signaling and thereby adversely affecting human health. Recent reports provide evidence for the presence of EDCs in commercially available bottled water, including steroid receptor agonists and antagonists. However, since these findings are based on biological data the causative chemicals remain unidentified and, therefore, inaccessible for toxicological evaluation. Thus, the aim of this study is to assess the antiestrogenic and antiandrogenic activity of bottled water and to identify the causative steroid receptor antagonists. We evaluated the antiestrogenic and antiandrogenic activity of 18 bottled water products in reporter gene assays for human estrogen receptor alpha and androgen receptor. Using nontarget high-resolution mass spectrometry (LTQ-Orbitrap Velos), we acquired corresponding analytical data. We combined the biological and chemical information to determine the exact mass of the tentative steroid receptor antagonist. Further MSn experiments elucidated the molecule’s structure and enabled its identification. We detected significant antiestrogenicity in 13 of 18 products. 16 samples were antiandrogenic inhibiting the androgen receptor by up to 90%. Nontarget chemical analysis revealed that out of 24520 candidates present in bottled water one was consistently correlated with the antagonistic activity. By combining experimental and in silico MSn data we identified this compound as di(2-ethylhexyl) fumarate (DEHF). We confirmed the identity and biological activity of DEHF and additional isomers of dioctyl fumarate and maleate using authentic standards. Since DEHF is antiestrogenic but not antiandrogenic we conclude that additional, yet unidentified EDCs must contribute to the antagonistic effect of bottled water. Applying a novel approach to combine biological and chemical analysis this is the first study to identify so far unknown EDCs in bottled water. Notably

  17. Identification of putative steroid receptor antagonists in bottled water: combining bioassays and high-resolution mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Martin Wagner

    Full Text Available Endocrine disrupting chemicals (EDCs are man-made compounds interfering with hormone signaling and thereby adversely affecting human health. Recent reports provide evidence for the presence of EDCs in commercially available bottled water, including steroid receptor agonists and antagonists. However, since these findings are based on biological data the causative chemicals remain unidentified and, therefore, inaccessible for toxicological evaluation. Thus, the aim of this study is to assess the antiestrogenic and antiandrogenic activity of bottled water and to identify the causative steroid receptor antagonists. We evaluated the antiestrogenic and antiandrogenic activity of 18 bottled water products in reporter gene assays for human estrogen receptor alpha and androgen receptor. Using nontarget high-resolution mass spectrometry (LTQ-Orbitrap Velos, we acquired corresponding analytical data. We combined the biological and chemical information to determine the exact mass of the tentative steroid receptor antagonist. Further MS(n experiments elucidated the molecule's structure and enabled its identification. We detected significant antiestrogenicity in 13 of 18 products. 16 samples were antiandrogenic inhibiting the androgen receptor by up to 90%. Nontarget chemical analysis revealed that out of 24520 candidates present in bottled water one was consistently correlated with the antagonistic activity. By combining experimental and in silico MS(n data we identified this compound as di(2-ethylhexyl fumarate (DEHF. We confirmed the identity and biological activity of DEHF and additional isomers of dioctyl fumarate and maleate using authentic standards. Since DEHF is antiestrogenic but not antiandrogenic we conclude that additional, yet unidentified EDCs must contribute to the antagonistic effect of bottled water. Applying a novel approach to combine biological and chemical analysis this is the first study to identify so far unknown EDCs in bottled water

  18. Combination of behaviorally sub-effective doses of glutamate NMDA and dopamine D1 receptor antagonists impairs executive function.

    Science.gov (United States)

    Desai, Sagar J; Allman, Brian L; Rajakumar, Nagalingam

    2017-04-14

    Impairment of executive function is a core feature of schizophrenia. Preclinical studies indicate that injections of either N-methyl d-aspartate (NMDA) or dopamine D1 receptor blockers impair executive function. Despite the prevailing notion based on postmortem findings in schizophrenia that cortical areas have marked suppression of glutamate and dopamine, recent in vivo imaging studies suggest that abnormalities of these neurotransmitters in living patients may be quite subtle. Thus, we hypothesized that modest impairments in both glutamate and dopamine function can act synergistically to cause executive dysfunction. In the present study, we investigated the effect of combined administration of "behaviorally sub-effective" doses of NMDA and dopamine D1 receptor antagonists on executive function. An operant conditioning-based set-shifting task was used to assess behavioral flexibility in rats that were systemically injected with NMDA and dopamine D1 receptor antagonists individually or in combination prior to task performance. Separate injections of the NMDA receptor antagonist, MK-801, and the dopamine D1 receptor antagonist, SCH 23390, at low doses did not impair set-shifting; however, the combined administration of these same behaviorally sub-effective doses of the antagonists significantly impaired the performance during set-shifting without affecting learning, retrieval of the memory of the initial rule, latency of responses or the number of omissions. The combined treatment also produced an increased number of perseverative errors. Our results indicate that NMDA and D1 receptor blockade act synergistically to cause behavioral inflexibility, and as such, subtle abnormalities in glutamatergic and dopaminergic systems may act cooperatively to cause deficits in executive function. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. TRA-418, a novel compound having both thromboxane A(2) receptor antagonistic and prostaglandin I(2) receptor agonistic activities: its antiplatelet effects in human and animal platelets.

    Science.gov (United States)

    Yamada, N; Miyamoto, M; Isogaya, M; Suzuki, M; Ikezawa, S; Ohno, M; Otake, A; Umemura, K

    2003-08-01

    TRA-418 is a novel compound that has been found in our screening for compounds having both thromboxane A2 (TP) receptor antagonistic and prostaglandin I2 (IP) receptor agonistic activities. In the binding assays, TRA-418 showed a 10-fold higher affinity to TP-receptors than IP-receptors. TRA-418 inhibited platelet aggregation induced by the TP-receptor agonist, U-46619 and by arachidonic acid at concentrations lower than those required for inhibition of ADP-induced aggregations. Furthermore, TRA-418 inhibited not only platelet aggregation induced by ADP alone, but also that induced by ADP in the presence of the TP-receptor antagonist, SQ-29548. When the IC50 values of TRA-418 for platelet aggregation were estimated in platelet preparations from monkeys, dogs, cats, and rats using ADP and arachidonic acid as the platelet stimulating agents, it was found that the values estimated in monkey platelets were quite similar to those estimated in human platelets. In ex vivo platelet aggregation in monkeys, TRA-418 exhibited significant inhibitory effects on arachidonic acid-induced aggregation in platelet preparations from monkeys treated at 3 micro g kg min-1 or higher doses, where neither a significant decrease in blood pressure nor a significant increase in heart rate was observed. These results are consistent with the fact that TRA-418 has a relatively potent TP-receptor antagonistic activity together with a relatively weak IP-receptor agonistic activity.

  20. Novel histamine H3 receptor antagonists: affinities in an H3 receptor binding assay and potencies in two functional H3 receptor models.

    Science.gov (United States)

    Schlicker, E; Kathmann, M; Reidemeister, S; Stark, H; Schunack, W

    1994-08-01

    1. We determined the affinities of ten novel H3 receptor antagonists in an H3 receptor binding assay and their potencies in two functional H3 receptor models. The novel compounds differ from histamine in that the aminoethyl side chain is replaced by a propyl or butyl chain linked to a polar group (amide, thioamide, ester, guanidine, guanidine ester or urea) which, in turn, is connected to a hexocyclic ring or to an alicyclic ring-containing alkyl residue [corrected]. 2. The specific binding of [3H]-N alpha-methylhistamine to rat brain cortex membranes was monophasically displaced by each of the ten compounds at pKi values ranging from 7.56 to 8.68. 3. Inhibition by histamine of the electrically evoked tritium overflow from mouse brain cortex slices preincubated with [3H]-noradrenaline was antagonized by the ten compounds and the concentration-response curve was shifted to the right with apparent pA2 values ranging from 7.07 to 9.20. 4. The electrically induced contraction in guinea-pig ileum strips (which was abolished by atropine) was inhibited by the H3 receptor agonists R-(-)-alpha-methylhistamine (pEC50 7.76), N alpha-methylhistamine (7.90) and imetit (8.18). The concentration-response curve of R-(-)-alpha-methylhistamine was shifted to the right by thioperamide (apparent pA2 8.79) and by the ten novel compounds (range of pA2 values 6.64-8.81). 5. The affinities and potencies were compared by linear regression analysis. This analysis was extended to thioperamide, the standard H3 receptor antagonist, which is also capable of differentiating between H3A and H3B sites. Comparison of the apparent pA2 values in the two functional H3 receptor models yielded a regression coefficient of 0.77 (PH3 receptor antagonists,and the nature of the H3 receptors in the guinea-pig ileum and mouse brain, are considered.

  1. Nonpeptide tachykinin receptor antagonists. III. SB 235375, a low central nervous system-penetrant, potent and selective neurokinin-3 receptor antagonist, inhibits citric acid-induced cough and airways hyper-reactivity in guinea pigs.

    Science.gov (United States)

    Hay, Douglas W P; Giardina, Giuseppe A M; Griswold, Don E; Underwood, David C; Kotzer, Charles J; Bush, Brian; Potts, William; Sandhu, Punam; Lundberg, Dave; Foley, James J; Schmidt, Dulcie B; Martin, Lenox D; Kilian, David; Legos, Jeffrey J; Barone, Frank C; Luttmann, Mark A; Grugni, Mario; Raveglia, Luca F; Sarau, Henry M

    2002-01-01

    In this report the in vitro and in vivo pharmacological and pharmacokinetic profile of (-)-(S)-N-(alpha-ethylbenzyl)-3-(carboxymethoxy)-2-phenylquinoline-4-carboxamide (SB 235375), a low central nervous system (CNS)-penetrant, human neurokinin-3 (NK-3) receptor (hNK-3R) antagonist, is described. SB 235375 inhibited (125)I-[MePhe(7)]-neurokinin B (NKB) binding to membranes of Chinese hamster ovary (CHO) cells expressing the hNK-3R (CHO-hNK-3R) with a K(i) = 2.2 nM and antagonized competitively NKB-induced Ca(2+) mobilization in human embryonic kidney (HEK) 293 cells expressing the hNK-3R (HEK 293-hNK-3R) with a K(b) = 12 nM. SB 235375 antagonized senktide (NK-3R)-induced contractions in rabbit isolated iris sphincter (pA(2) = 8.1) and guinea pig ileal circular smooth muscles (pA(2) = 8.3). SB 235375 was selective for the hNK-3R compared with hNK-1 (K(i) > 100,000 nM) and hNK-2 receptors (K(i) = 209 nM), and was without effect, at 1 microM, in 68 other receptor, enzyme, and ion channel assays. Intravenous SB 235375 produced a dose-related inhibition of miosis induced by i.v. senktide in the rabbit (ED(50) of 0.56 mg/kg). Intraperitoneal SB 235375 (10-30 mg/kg) inhibited citric acid-induced cough and airways hyper-reactivity in guinea pigs. In mice oral SB 235375 (3-30 mg/kg) was without significant effect on the behavioral responses induced by intracerebral ventricular administration of senktide. Pharmacokinetic evaluation in the mouse and rat revealed that oral SB 235375 was well absorbed systemically but did not effectively cross the blood-brain barrier. The preclinical profile of SB 235375, encompassing high affinity, selectivity, oral activity, and low CNS penetration, suggests that it is an appropriate tool compound to define the pathophysiological roles of the NK-3Rs in the peripheral nervous system.

  2. Discovery and optimization of potent and selective functional antagonists of the human adenosine A2B receptor.

    Science.gov (United States)

    Bedford, Simon T; Benwell, Karen R; Brooks, Teresa; Chen, Ijen; Comer, Mike; Dugdale, Sarah; Haymes, Tim; Jordan, Allan M; Kennett, Guy A; Knight, Anthony R; Klenke, Burkhard; LeStrat, Loic; Merrett, Angela; Misra, Anil; Lightowler, Sean; Padfield, Anthony; Poullennec, Karine; Reece, Mark; Simmonite, Heather; Wong, Melanie; Yule, Ian A

    2009-10-15

    We herein report the discovery of a novel class of antagonists of the human adenosine A2B receptor. This low molecular weight scaffold has been optimized to offer derivatives with potential utility for the alleviation of conditions associated with this receptor subtype, such as nociception, diabetes, asthma and COPD. Furthermore, preliminary pharmacokinetic analysis has revealed compounds with profiles suitable for either inhaled or systemic routes of administration.

  3. Synthesis and characterization of a series of chiral alkoxymethyl morpholine analogs as dopamine receptor 4 (D4R) antagonists

    Science.gov (United States)

    Witt, Jonathan O.; McCollum, Andrea L.; Hurtado, Miguel A.; Huseman, Eric D.; Jeffries, Daniel E.; Temple, Kayla J.; Plumley, Hyekyung C.; Blobaum, Anna L.; Lindsley, Craig W.; Hopkins, Corey R.

    2017-01-01

    Herein, we report the synthesis and structure–activity relationship of a series of chiral alkoxymethyl morpholine analogs. Our efforts have culminated in the identification of (S)-2-(((6-chloropyridin-2-yl) oxy)methyl)-4-((6-fluoro-1H-indol-3-yl)methyl)morpholine as a novel potent and selective dopamine D4 receptor antagonist with selectivity against the other dopamine receptors tested (D1, D2L, D2S, D3, and D5). PMID:27080176

  4. Differential regulation of human cardiac β-adrenergic and muscarinic receptors by chronic β-adrenoceptor antagonist treatment

    OpenAIRE

    Motomura, S.; Deighton, N M; Zerkowski, H.-R.; Khamssi, M.; Brodde, O.-E.

    1990-01-01

    In patients undergoing coronary artery bypass grafting chronic β1-adrenoceptor antagonist treatment increased right atrial β1-adrenoceptor number, did not affect β2-adrenoceptor number and decreased muscarinic M2-receptor number. Concomitantly, the M2-receptor-mediated negative inotropic effect of carbachol was reduced, while the β1-adrenoceptor-mediated positive inotropic effect of noradrenaline was not altered. The β2-adrenoceptor mediated positive inotropic effect of procaterol, however, w...

  5. Discovery and characterization of ACT-335827, an orally available, brain penetrant orexin receptor type 1 selective antagonist.

    Science.gov (United States)

    Steiner, Michel A; Gatfield, John; Brisbare-Roch, Catherine; Dietrich, Hendrik; Treiber, Alexander; Jenck, Francois; Boss, Christoph

    2013-06-01

    Stress relief: Orexin neuropeptides regulate arousal and stress processing through orexin receptor type 1 (OXR-1) and 2 (OXR-2) signaling. A selective OXR-1 antagonist, represented by a phenylglycine-amide substituted tetrahydropapaverine derivative (ACT-335827), is described that is orally available, penetrates the brain, and decreases fear, compulsive behaviors and autonomic stress reactions in rats.

  6. Effects of the CGRP receptor antagonist BIBN4096BS on capsaicin-induced carotid haemodynamic changes in anaesthetised pigs.

    NARCIS (Netherlands)

    K. Kapoor (Kapil); U. Arulmani (Udayasankar); J.P. Heiligers (Jan); I.M. Garrelds (Ingrid); E.W. Willems (Edwin); H. Doods (Henri); C.M. Villalón (Carlos); P.R. Saxena (Pramod Ranjan)

    2003-01-01

    textabstract1. Calcitonin gene-related peptide (CGRP), a potent vasodilator released from capsaicin-sensitive trigeminal sensory nerves, seems to be involved in the pathogenesis of migraine. Hence, CGRP receptor antagonists may serve as a novel treatment for migraine. This study wa

  7. The effect of ondansetron, a 5-HT3 receptor antagonist, in chronic fatigue syndrome: a randomized controlled trial.

    NARCIS (Netherlands)

    The, G.K.H.; Bleijenberg, G.; Buitelaar, J.K.; Meer, J.W.M. van der

    2010-01-01

    BACKGROUND: Accumulating data support the involvement of the serotonin (5-hydroxytryptamine [5-HT]) system in the pathophysiology of chronic fatigue syndrome. Neuropharmacologic studies point to a hyperactive 5-HT system, and open-label treatment studies with 5-HT(3) receptor antagonists have shown

  8. Synthesis and Properties of a New Water-Soluble Prodrug of the Adenosine A2A Receptor Antagonist MSX-2

    Directory of Open Access Journals (Sweden)

    Christa E. Müller

    2008-02-01

    Full Text Available The compound L-valine-3-{8-[(E-2-[3-methoxyphenylethenyl]-7-methyl-1-propargylxanthine-3-yl}propyl ester hydrochloride (MSX-4 was synthesized as an aminoacid ester prodrug of the adenosine A2A receptor antagonist MSX-2. It was found to bestable in artificial gastric acid, but readily cleaved by pig liver esterase.

  9. South African plants used in traditional medicine to treat epilepsy have an antagonistic effect on NMDA receptor currents

    DEFF Research Database (Denmark)

    Marchetti, Carla; Gavazzo, Paola; Stafford, Gary Ivan

    2011-01-01

    Several Searsia species (Anacardiaceae), including Searsia dentata and Searsia pyroides, are used in South Africa traditional medicine to treat epilepsy. Ethanol leaf extracts of these plants have been shown to act as possible antagonists of N-methyl-d-aspartate (NMDA)-type glutamate receptors....

  10. Effects of dopamine D1-like and D2-like antagonists on cocaine discrimination in muscarinic receptor knockout mice.

    Science.gov (United States)

    Thomsen, Morgane; Caine, Simon Barak

    2016-04-05

    Muscarinic and dopamine brain systems interact intimately, and muscarinic receptor ligands, like dopamine ligands, can modulate the reinforcing and discriminative stimulus (S(D)) effects of cocaine. To enlighten the dopamine/muscarinic interactions as they pertain to the S(D) effects of cocaine, we evaluated whether muscarinic M1, M2 or M4 receptors are necessary for dopamine D1 and/or D2 antagonist mediated modulation of the S(D) effects of cocaine. Knockout mice lacking M1, M2, or M4 receptors, as well as control wild-type mice and outbred Swiss-Webster mice, were trained to discriminate 10mg/kg cocaine from saline in a food-reinforced drug discrimination procedure. Effects of pretreatments with the dopamine D1 antagonist SCH 23390 and the dopamine D2 antagonist eticlopride were evaluated. In intact mice, both SCH 23390 and eticlopride attenuated the cocaine discriminative stimulus effect, as expected. SCH 23390 similarly attenuated the cocaine discriminative stimulus effect in M1 knockout mice, but not in mice lacking M2 or M4 receptors. The effects of eticlopride were comparable in each knockout strain. These findings demonstrate differences in the way that D1 and D2 antagonists modulate the S(D) effects of cocaine, D1 modulation being at least partially dependent upon activity at the inhibitory M2/M4 muscarinic subtypes, while D2 modulation appeared independent of these systems.

  11. Adenosine-diphosphate (ADP) receptor antagonists for the prevention of cardiovascular disease in type 2 diabetes mellitus (Review)

    NARCIS (Netherlands)

    Valentine, N.; Laar, F.A. van de; Driel, M.L. van

    2012-01-01

    BACKGROUND: Cardiovascular disease (CVD) is the most prevalent complication of type 2 diabetes with an estimated 65% of people with type 2 diabetes dying from a cause related to atherosclerosis. Adenosine-diphosphate (ADP) receptor antagonists like clopidogrel, ticlopidine, prasugrel and ticagrelor

  12. Changes in plasma concentrations of interleukin-6 and interleukin-1 receptor antagonists in response to adrenaline infusion in humans

    DEFF Research Database (Denmark)

    Søndergaard, S R; Ostrowski, K.; Ullum, H

    2000-01-01

    To investigate the possible role of adrenaline in the response of interleukin (IL)-6 and IL-1 receptor antagonists (ra) to extreme physiological conditions such as trauma and exercise, we examined the concentrations in the plasma of these cytokines during an adrenaline infusion. Given the fact th...

  13. Finerenone : third-generation mineralocorticoid receptor antagonist for the treatment of heart failure and diabetic kidney disease

    NARCIS (Netherlands)

    Liu, Licette C. Y.; Schutte, Elise; Gansevoort, Ron T.; van der Meer, Peter; Voors, Adriaan A.

    2015-01-01

    Introduction: The mineralocorticoid receptor antagonists (MRAs) spironolactone and eplerenone reduce the risk of hospitalizations and mortality in patients with heart failure (HF) with reduced ejection fraction (HFrEF), and attenuate progression of diabetic kidney disease. However, their use is limi

  14. The cholecystokinin-B receptor antagonist CI-988 failed to affect CCK-4 induced symptoms in panic disorder patients

    NARCIS (Netherlands)

    vanMegen, HJGM; Westenberg, HGM; denBoer, JA; Slaap, B; vanEsRadhakishun, F; Pande, AC

    1997-01-01

    The effects of the cholecystokinin-B (CCK-B) receptor antagonist CI-988 on symptoms elicited by the cholecystokinin tetrapeptide (CCK4) were studied in DSM-IIIR patients with panic disorder. The study employed a double-blind, two-period incomplete block design. Patients (n = 14) received two differe

  15. Cannabinoid CB1 receptor antagonist rimonabant disrupts nicotine reward-associated memory in rats.

    Science.gov (United States)

    Fang, Qin; Li, Fang-Qiong; Li, Yan-Qin; Xue, Yan-Xue; He, Ying-Ying; Liu, Jian-Feng; Lu, Lin; Wang, Ji-Shi

    2011-10-01

    Exposure to cues previously associated with drug intake leads to relapse by activating previously acquired memories. Based on previous findings, in which cannabinoid CB(1) receptors were found to be critically involved in specific aspects of learning and memory, we investigated the role of CB(1) receptors in nicotine reward memory using a rat conditioned place preference (CPP) model. In Experiment 1, rats were trained for CPP with alternating injections of nicotine (0.5mg/kg, s.c.) and saline to acquire the nicotine-conditioned memory. To examine the effects of rimonabant on the reconsolidation of nicotine reward memory, rats were administered rimonabant (0, 0.3, and 3.0mg/kg, i.p.) immediately after reexposure to the drug-paired context. In Experiment 2, rats were trained for CPP similarly to Experiment 1. To examine the effects of rimonabant on the reinstatement of nicotine reward memory, rimonabant (0, 0.3, and 3.0mg/kg, i.p.) was administered before the test of nicotine-induced CPP reinstatement. In Experiment 3, to evaluate whether rimonabant itself produces a reward memory, rats were trained for CPP with alternating injections of different doses of rimonabant (0, 0.3, and 3.0mg/kg) and saline. Rimonabant at a dose of 3.0mg/kg significantly disrupted the reconsolidation of nicotine memory and significantly blocked the reinstatement of nicotine-induced CPP. However, rimonabant itself did not produce CPP. These findings provide clear evidence that CB(1) receptors play a role in nicotine reward memory, suggesting that CB(1) receptor antagonists may be a potential target for managing nicotine addiction.

  16. Effects of 5-HT4 receptor agonists and antagonists in learning.

    Science.gov (United States)

    Meneses, A; Hong, E

    1997-03-01

    In the present work, the effects of pre- or post-training (ip) injection of BIMU1 and BIMU8 (5-HT4 agonists) were figured out in the autoshaping learning task. Furthermore, the post-training effects of these agonists after treatment with SDZ 205-557 and GR 125487D (5-HT4 antagonists) or p-Chloroamphetamine (PCA) were also explored. Animals were individually trained in a lever-press response on the autoshaping task and 24 hours later were tested. The results showed that pre-training injection of BIMU1 (5 20 mg/Kg) or BIMU8 (20 mg/Kg) increased the CR; in contrast, the post-training administration of BIMU1 (10-20 mg/Kg) or BIMU8 (5 and 20 mg/Kg) decreased it. Further experiments revealed that the post-training injections of SDZ 205-557 (1.0-10.0 mg/Kg) or GR 125487D (0.39-1.56 mg/Kg) by themselves did not alter the CR. When BIMU1 or BIMU8 was administered to rats pretreated with SDZ 205-557 (10 mg/Kg) or GR 125487D (0.78 mg/Kg), the decrement induced by 5-HT4 the agonists was reversed; in contrast, the administration of PCA failed to modify the CR or the agonist-induced responses. The findings showed that the pre-training stimulation of 5-HT4 receptors enhanced the acquisition of CR, while, post-training activation of 5-HT4 receptors, impaired the consolidation of learning. The latter effect was not altered by PCA pretreatment. The data show that 5-HT4 receptors are involved in the acquisition and consolidation of learning. It seems that postsynaptic 5-HT4 receptors are involved in the latter effect.

  17. Successful virtual screening for a submicromolar antagonist of the neurokinin-1 receptor based on a ligand-supported homology model.

    Science.gov (United States)

    Evers, Andreas; Klebe, Gerhard

    2004-10-21

    The neurokinin-1 (NK1) receptor belongs to the family of G-protein-coupled receptors (GPCRs), which represents one of the most relevant target families in small-molecule drug design. In this paper, we describe a homology modeling of the NK1 receptor based on the high-resolution X-ray structure of rhodopsin and the successful virtual screening based on this protein model. The NK1 receptor model has been generated using our new MOBILE (modeling binding sites including ligand information explicitly) approach. Starting with preliminary homology models, it generates improved models of the protein binding pocket together with bound ligands. Ligand information is used as an integral part in the homology modeling process. For the construction of the NK1 receptor, antagonist CP-96345 was used to restrain the modeling. The quality of the obtained model was validated by probing its ability to accommodate additional known NK1 antagonists from structurally diverse classes. On the basis of the generated model and on the analysis of known NK1 antagonists, a pharmacophore model was deduced, which subsequently guided the 2D and 3D database search with UNITY. As a following step, the remaining hits were docked into the modeled binding pocket of the NK1 receptor. Finally, seven compounds were selected for biochemical testing, from which one showed affinity in the submicromolar range. Our results suggest that ligand-supported homology models of GPCRs may be used as effective platforms for structure-based drug design.

  18. Reduced expression of haloperidol conditioned catalepsy in rats by the dopamine D3 receptor antagonists nafadotride and NGB 2904.

    Science.gov (United States)

    Banasikowski, Tomek J; Beninger, Richard J

    2012-10-01

    Haloperidol, a dopamine (DA) D2 receptor-preferring antagonist, produces catalepsy whereby animals maintain awkward posture for a period of time. Sub-threshold doses of haloperidol fail to produce catalepsy initially, however, when the drug is given repeatedly in the same test environment, gradual day-to-day increases in catalepsy are observed. More importantly, if sensitized rats are injected with saline instead of haloperidol they continue to be cataleptic in the test environment suggesting that environment-drug associations may play a role. DA D3 receptors have been implicated in a number of conditioned behaviors. We were interested if DA D3 receptors contribute to catalepsy sensitization and conditioning in rats. We tested this hypothesis using the DA D3 receptor-selective antagonist NGB 2904 (0.5, 1.8 mg/kg) and the DA D3 receptor-preferring antagonist nafadotride (0.1, 0.5 mg/kg). For 10 consecutive conditioning days rats were treated with one of the D3 receptor antagonists alone or in combination with haloperidol (0.25 mg/kg) and tested for catalepsy, quantified by the time a rat remained with its forepaws on a horizontal bar. On test day (day 11), rats were injected with saline or the D3 receptor antagonist and tested for conditioned catalepsy in the previously drug-paired environment. Rats treated with NGB 2904 or nafadotride alone did not develop catalepsy. Rats treated with haloperidol or haloperidol plus NGB 2904 or nafadotride developed catalepsy sensitization with repeated conditioning. When injected with saline they continued to exhibit catalepsy in the test environment--now conditioned. On the other hand, NGB 2904 (1.8 mg/kg) or nafadotride (0.5 mg/kg) given on the test day (after sensitization to haloperidol) significantly attenuated the expression of conditioned catalepsy. Our data suggest that the D3 receptor antagonist NGB 2904 (1.8 mg/kg) and nafadotride (0.5 mg/kg) significantly attenuate conditioned catalepsy in rats when given in test but

  19. Effects of 5-HT1A receptor agonists and NMDA receptor antagonists in the social interaction test and the elevated plus maze.

    Science.gov (United States)

    Dunn, R W; Corbett, R; Fielding, S

    1989-10-01

    The effects of several 5-HT1A agonists and excitatory amino acid antagonists were compared to the standard benzodiazepines, diazepam and chlordiazepoxide (CDP) in two assays predictive of anxiolytic activity, the social interaction and elevated plus maze procedures. Indicative of anxiolytic effects the 5-HT1A agonists, buspirone, gepirone and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) all significantly increased social interaction time and open arm exploration time in the social interaction and elevated plus maze procedures, respectively. Likewise, anxiolytic activity in these assays were also produced by the competitive N-methyl-D-aspartate (NMDA) antagonists, 2-amino-5-phosphonovaleric acid (AP-5), 2-amino-7-phosphonoheptanoic acid (AP-7), 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) and the non-competitive NMDA antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) while NMDA produced anxiogenic effects. Furthermore, the anxiolytic effects of these agents were of equal magnitude to the benzodiazepines. These two classes of compounds were differentiated in the yohimbine-induced seizure assay, with the NMDA antagonists dose dependently antagonizing seizures similar to the benzodiazepines while the 5-HT1A agonists were inactive. These results suggest that the 5-HT1A agonists and the NMDA antagonists may be potential non-classical anxiolytic agents with different mechanisms of action.

  20. Characterization of a novel small molecule subtype specific estrogen-related receptor alpha antagonist in MCF-7 breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Michael J Chisamore

    Full Text Available BACKGROUND: The orphan nuclear receptor estrogen-related receptor alpha (ERRalpha is a member of the nuclear receptor superfamily. It was identified through a search for genes encoding proteins related to estrogen receptor alpha (ERalpha. An endogenous ligand has not been found. Novel ERRalpha antagonists that are highly specific for binding to the ligand binding domain (LBD of ERRalpha have been recently reported. Research suggests that ERRalpha may be a novel drug target to treat breast cancer and/or metabolic disorders and this has led to an effort to characterize the mechanisms of action of N-[(2Z-3-(4,5-dihydro-1,3-thiazol-2-yl-1,3-thiazolidin-2-yl idene]-5H dibenzo[a,d][7]annulen-5-amine, a novel ERRalpha specific antagonist. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate this ERRalpha ligand inhibits ERRalpha transcriptional activity in MCF-7 cells by luciferase assay but does not affect mRNA levels measured by real-time RT-PCR. Also, ERalpha (ESR1 mRNA levels were not affected upon treatment with the ERRalpha antagonist, but other ERRalpha (ESRRA target genes such as pS2 (TFF1, osteopontin (SPP1, and aromatase (CYP19A1 mRNA levels decreased. In vitro, the ERRalpha antagonist prevents the constitutive interaction between ERRalpha and nuclear receptor coactivators. Furthermore, we use Western blots to demonstrate ERRalpha protein degradation via the ubiquitin proteasome pathway is increased by the ERRalpha-subtype specific antagonist. We demonstrate by chromatin immunoprecipitation (ChIP that the interaction between ACADM, ESRRA, and TFF1 endogenous gene promoters and ERRalpha protein is decreased when cells are treated with the ligand. Knocking-down ERRalpha (shRNA led to similar genomic effects seen when MCF-7 cells were treated with our ERRalpha antagonist. CONCLUSIONS/SIGNIFICANCE: We report the mechanism of action of a novel ERRalpha specific antagonist that inhibits transcriptional activity of ERRalpha, disrupts the constitutive