Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:50-67-9 (5-HT)
 31,727 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. An 'atypical' 5-HT2 receptor which is located on the endothelium of rat jugular vein has been described. In the present study we have further defined the nature of the 5-HT2 receptor subtype present in this preparation. 2. In experiments conducted in the presence of ketanserin to preclude involvement of 5-HT2 receptors, the mixed 5-HT2B/2C antagonist, SB 200646, acted as an antagonist of 5-HT at the endothelial 5-HT receptor (pA2 = 7.2). Yohimbine, which exhibits negligible affinity for rat 5-HT2C receptors but has high 5-HT2B receptor affinity, acted as a potent but non-surmountable antagonist (pA2 > or = 7.3) in rat jugular vein. Neither yohimbine nor SB 200646 affected endothelium-dependent relaxations induced by carbachol. 3. Mianserin also acted as a surmountable antagonist (pA2 = 7.3) and the 5-HT2B agonist, BW 723C86, acted as a potent partial agonist (pEC50 [95% C L], intrinsic activity +/- s.e. mean = 7.9 [7.6-8.3], 0.84 +/- 0.04). Responses to BW 723C86 were antagonized by SB 200646 (0.3 microM) yielding an 'apparent' pA2 [95% CL] of 7.03 [6.76-7.32]. 4. These data are consistent with the presence of 5-HT2B receptors mediating endothelium-dependent relaxation of rat jugular vein.
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PMID:Mediation by 5-hydroxytryptamine2B receptors of endothelium-dependent relaxation in rat jugular vein. 788 40

The serotonin (5-HT) is implicated in many centrally-regulated functions and has shown to be involved in affective disorders, such as depression and anxiety disorders. Recent progress in pharmacology and molecular neurobiology have confirmed the concept of the heterogeneity of 5-HT receptors and permitted reformulation of new hypothesis concerning antidepressant mechanisms of action, in particular those concerning serotoninergic receptors. Up to date, among the 5-HT defined sites, only 13 have been cloned, and several subfamilies have been described. Particularly, the 5-HT1 family containing receptors: 5-HT1A, 5-HT1B/1D, 5-HT1E and 5-HT1F. The 5-HT2 family includes receptors that stimulate phospholipase C: 5-HT2A (previously termed 5-HT2), 5-HT2B and 5-HT2C (previously termed 5-HT1C). Concerning 5-HT2 family, it is possible that some 5-HT binding drugs properties initially attributed to 5-HT2A receptors, might well be mediated by 5-HT2C receptors. Recently, medifoxamine (Cledial) activities on 5-HT systems have been shown. In particular, these activities are related on 5-HT2C and/or 5-HT2A binding sites. Results indicate that, in vitro, medifoxamine affinities (Ki) are near to 1 microM, for both 5-HT2C and 5-HT2A sites (ratio = 1.42). On the other hand, m-CPP, an 5-HT2C agonist, considered as a reference compound, has the same affinities that medifoxamine, but a higher one for 5-HT2A (ratio = 3.42). In animals models considered as predictive for psychotropic activity in human, we investigate in rat the impact of medifoxamine on 5-HT2C receptors, using Learned-Helplessness model (LH) and the social interaction test.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The role of type 2 serotonin receptors, 5-HT2A and 5-HT2C, in depressive disorders: effect of medifoxamine]. 798 7

One of the most profound increases in vascular responsiveness in hypertension has been observed for serotonin (5-hydroxytryptamine, 5-HT). This study investigates the hypothesis that the increase in vascular responsiveness to 5-HT is the result of altered 5-HT receptor signal transduction. Mesenteric arteries were dissected from deoxycorticosterone- (DOCA) salt hypertensive and sham-normotensive rats for use in isolated tissue experiments. Agonist contractile potencies indicated that a 5-HT2 receptor mediates contraction to 5-HT in both sham and DOCA-salt arteries. In arteries from sham rats, ketanserin (5-HT2A/5-HT2C selective), LY53857 (5-HT2 selective) and spiperone (5-HT2A/5-HT2C selective) shifted contraction to 5-HT (pKB = 8.58, 8.35 and 9.52, respectively) indicating that a 5-HT2A receptor mediates contraction in arteries from normotensive rats. By contrast, ketanserin and spiperone did not shift contraction to 5-HT in DOCA-salt mesenteric arteries (pKB > 6.52, > 7.52, respectively). LY53857 did shift the response to 5-HT in DOCA-salt mesenteric arteries (pKB = 7.85). Thus, contraction in arteries from DOCA-salt rats is predominantly mediated by 5-HT2B receptors. Unlike the 5-HT receptor in the sham mesenteric artery and aorta (5-HT2A receptor), the 5-HT receptor in DOCA-salt mesenteric arteries and stomach fundus (5-HT2B receptor) were relatively insensitive to phenoxybenzamine (10-300 nM). These data suggest that the 5-HT2B receptor is insensitive to phenoxybenzamine, is increased in number or, alternatively, has increased G protein coupling. DOCA-salt mesenteric arteries were more sensitive to contraction by the direct G protein stimulator AIF4- (-log EC50 [M]: DOCA-salt = 2.82 +/- 0.04; sham = 2.55 +/- 0.03, P < .05). PCR analyses indicated an increase in mRNA for the 5-HT2B receptor in mesenteric arteries of DOCA-salt hypertensive arteries, supporting an increase in receptor number. Taken together these studies demonstrate significant changes in 5-HT receptor signal transduction in DOCA-salt hypertension, both at the level of the receptor and G protein and may provide one reason why ketanserin has proved to be a relatively ineffective antihypertensive agent in some forms of hypertension.
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PMID:The 5-hydroxytryptamine2B receptor and 5-HT receptor signal transduction in mesenteric arteries from deoxycorticosterone acetate-salt hypertensive rats. 862 22

Over the last several years the use of molecular cloning technology has revealed a vast diversity among serotonin (5-HT) receptors, whereby what was previously thought to be a family of three pharmacologically defined classes of 5-HT receptors is actually composed of seven distinct subfamilies designated 5-HT1-7. The 5-HT1, 5-HT2, and 5-HT5 subfamilies currently consist of five, three and two subtypes respectively while the 5-HT3, 5-HT4, 5-HT6, and 5-HT7 "subfamilies" have at present one subtype each. Fourteen separate genes encode 13 receptors which fall in the superfamily of G protein-coupled receptors and one ligand-gated ion channel receptor. Our lab has contributed to the elucidation of this subtype diversity by cloning the cDNAs from both rat and human encoding the 5-HT2B receptor. This receptor subtype is equally homologous (approximately 70%) to the 5-HT2A and 5-HT2C receptors when amino acids comprising the transmembrane domains are compared and is clearly the third member of the 5-HT2 subfamily. The 5-HT2B receptor has been shown to couple to phosphoinositide hydrolysis as do the other two members of this subfamily when expressed in AV12-664 cells. Limited pharmacological analyses indicated that both rat and human 5-HT2B receptors are similar but distinguishable. With one tantalizing exception, the mRNAs for these receptors appear to be similarly distributed within rat and human. The 5-HT2B receptor mRNA is not found in rat brain, whereas in human brain it has been identified in multiple regions. This later finding suggests that the 5-HT2B receptor may be serving a unique CNS function in man that is absent in rat.
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PMID:Molecular biology of serotonin receptors. 869 42

Several pharmaceuticals are frequently dispensed to prevent or reduce the occurrence of migraine attacks. The prophylactic effect of these drugs has been suggested to be caused through blockade of serotonin (5-HT) receptors of type 5-HT2B or 5-HT2C. To elucidate which of these receptors is involved, we first used radioligand binding assays to determine the pharmacological profile of the human and rat-5-HT2B receptor. Furthermore, the potency of drugs used in migraine prophylaxis to stimulate or inhibit 5-HT2B or 5-HT2C receptor-mediated potency of drugs used in migraine prophylaxis to stimulate or inhibit 5-HT2B or 5-HT2C receptor-mediated phosphatidyl inositol hydrolysis was measured. All these drugs were found to block both human receptors. Correlation of the receptor affinities with the potencies used in migraine prophylaxis showed significant correlations, which were better for the 5-HT2B (P = 0.001) than for the 5-HT2C receptor (P = 0.005). Migraine headache is thought to be transmitted by the trigeminal nerve from the meninges and their blood vessels. Using the reverse transcription-polymerase chain reaction, the expression patterns of all cloned G-protein-coupled serotonin receptors were analysed in various human meningeal tissues. All tissues expressed 5-HT1Dbeta, 5-HT2A, 5-HT2B, 5-HT4 and 5-HT7 mRNAs. Only trace amounts of 5-HT2C receptor mRNA were found. With organ bath experiments we showed that the 5-HT2B receptor stimulated the relaxation of the pig cerebral artery via the release of nitric oxide. Our data support the hypothesis that 5-HT2B receptors located on endothelial cells of meningeal blood vessels trigger migraine headache through the formation of nitric oxide.
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PMID:Activation of meningeal 5-HT2B receptors: an early step in the generation of migraine headache? 874 44

The isolated rat stomach fundus preparation, a sensitive bioassay to evaluate serotonin-(5-HT) like activity, was used as a model to study the effects of parthenolide (PAR), a component to Tanacetum parthenium (feverfew), on 5-HT storage, release and stimulation of the 5-HT2B receptor. Cumulative-concentration response curves to 5-HT and the indirect-acting serotonergics fenfluramine (F) and dextroamphetamine (DA) on fundus were obtained in the presence and absence of 1 x 10(-6) to 1 x 10(-5) PAR. 5-HT release elicited by F and DA was indirectly assessed by comparing the contraction elicited by these compounds on tissues from reserpine-treated, L-p-chlorophenylalanine (l-PCPA)-treated and untreated rats. The observed order of agonist potencies on intact fundus was: 5-HT > DA > F and the order of intrinsic activity was: 5-HT > DA > F. PAR did not show agonist effects nor antagonism toward 5-HT on rat fundus at all concentrations used. However, PAR antagonized non-competitively the effects of F and DA. Contractile responses to 5-HT were not significantly different on mucosa-denuded fundus and tissue strips from untreated, l-PCPA- and reserpine-treated rats. PAR appears to inhibit 5-HT release mediated responses by the indirect-acting 5-HT agonists on fundal tissue.
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PMID:Parthenolide inhibits the contractile responses of rat stomach fundus to fenfluramine and dextroamphetamine but not serotonin. 877 1

The 5-Hydroxytryptamine (5-HT)2C receptor (originally known as the 5-HT1C receptor) is a member of the 5-HT2 subfamily of G protein coupled receptors, which is known to couple to phospholipase C. Within the 5-HT2 subfamily, only the 5-HT2C receptor also coupled to inhibition of forskolin-stimulated cAMP production when expressed at high density (12 pmol/mg membrane protein) in stably transformed AV12 cells. The 5-HT2C receptor coupled with high efficacy to both phospholipase C as measured by IP3 (inositol 1,4,5-trisphosphate) production and to inhibition of forskolin-stimulated cAMP production (EC50 = 2.98 nM +/- 0.9 and IC50 = 47.99 nM +/- 10.25 respectively). The 5-HT2A and 5-HT2B receptors, while coupling to phospholipase C with high affinity (EC50s of 19.24 nM +/- 6.44 and 1.24 nM +/- 0.136 respectively), did not decrease adenylyl cyclase activity. The 5-HT2C receptor actions in both systems showed the expected pharmacology for the 5-HT2C receptor, e.g., mesulergine antagonized the effects of 5-HT and spiperone did not. Preincubation of cells with PTX showed that the G protein coupling of the 5-HT2C receptor to phospholipase C is PTX insensitive, while the G protein coupling to inhibition of adenylyl cyclase is PTX sensitive, even to concentrations as low as 20 ng/ml of PTX. PTX pretreatment of the 5-HT2C bearing cells also unmasked a small stimulatory effect on adenylyl cyclase. When expressed at low density the 5-HT2C receptor potentiated forskolin-stimulated cAMP production by 2 fold while still maintaining its ability to enhance PI hydrolysis. A more modest potentiation of cAMP production was noted with low density expression of the 5-HT2B receptor. Thus the ability of the 5-HT2C receptor to interact with several effectors through at least two different G proteins is, in part, receptor subtype specific but also influenced by receptor density.
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PMID:Receptor subtype and density determine the coupling repertoire of the 5-HT2 receptor subfamily. 880 27

1. SB 206553 (5-methyl-1-(3-pyridylcarbamoyl)-1,2,3,5-tetrahydropyrrolo[2 ,3-f]indole) displays a high affinity (pK1 7.9) for the cloned human 5-HT2C receptor expressed in HEK 293 cells and the 5-HT2B receptor (pA2 8.9) as measured in the rat stomach fundus preparation. SB 206553 has low affinity for cloned human 5-HT2A receptors expressed in HEK 293 cells (pK1 5.8) and (pK1 < 6) for a wide variety of other neurotransmitter receptors. 2. SB 206553 appears to be a surmountable antagonist of 5-HT-stimulated phosphoinositide hydrolysis in HEK 293 cells expressing the human 5-HT2C receptor (pKB 9.0). 3. The compound potently (ID50 5.5 mg kg-1, p.o., 0.27 mg kg-1, i.v.) inhibited the hypolocomotor response to m-chlorophenylpiperazine (mCPP), a putative model of 5-HT2C/5-HT2B receptor function in vivo. 4. At similar doses (2-20 mg kg-1, p.o.) SB 206553 increased total interaction scores in a rat social interaction test and increased punished responding in a rat Geller-Seifter conflict test. These effects are consistent with the possession of anxiolytic properties. 5. SB 206553 also increased suppressed responding in a marmoset conflict model of anxiety at somewhat higher doses (15 and 20 mg kg-1, p.o.) but also reduced unsuppressed responding. 6. These results suggest that SB 206553 is a potent mixed 5-HT2C/5-HT2B receptor antagonist with selectivity over the 5-HT2A and all other sites studied and possesses anxiolytic-like properties.
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PMID:In vitro and in vivo profile of SB 206553, a potent 5-HT2C/5-HT2B receptor antagonist with anxiolytic-like properties. 882 30

Modifications in serotonin (5-HT) neurotransmission have been associated with the physiopathology of anxiety and depression. Among the numerous 5-HT receptor subtypes, several (5-HT1A, 5-HT1B, 5-HT2 and 5-HT3) could be involved in these etiologies. By using a murine genetic model, we attempted to correlate variations in the density of receptor subtypes with modifications of anxiety-related behaviors. From a classic inbred strain (C57BL/6ByJ) and a linkage-testing inbred strain (ABP/Le), segregated F(2) populations for 3 loci located in the 4th, 7th and 9th chromosomes have been selected for their different responses in anxiety-related behavioral tests. The regional density of 5-HT1A, 5-HT1B, 5-HT2A and 5-HT2B receptors has been measured in the brains of parental strains, F(1) and F(2) populations by quantitative autoradiography. The results suggest that chromosomal fragments containing the brown, pink-eyed dilution and the short-ear loci, previously shown to be involved in anxiogenic processes, are mainly associated with a variation in the density of the 5-HT1B receptors.
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PMID:An autoradiographic study of serotonergic receptors in a murine genetic model of anxiety-related behaviors. 883 59

Local delivery of serotonin (5-HT) produces a rapid edematous response in soft tissues via increased fluid extravasation which is prevented by 5-HT2 antagonists such as ketanserin or mianserin. Here we report the effects of a new class of aminoguanidine 5-HT2 antagonists, with relative selectivity for 5-HT2A receptors which are potent inhibitors of 5-HT-induced paw edema in the rat. Radioligand binding studies with 125I DOI on human 5-HT2A and 5-HT2C receptors and with 3H-5-HT on human 5-HT2B receptors demonstrated that, LY314228, and LY320954 displayed some selectivity for the 5-HT2A receptor. When compared to binding at other 5-HT2 receptor subtypes, LY314228 had an 18.6-fold greater affinity for the 5-HT2A site over the 5-HT2B site, and 2.6 fold greater at the 5-HT2C site. LY320954 displayed similar preference for 5-HT2A sites. Both compounds also inhibited 5-HT-induced paw swelling in rats, with ED50's of 6.4 and 4.8 mg/kg (for LY314228 and LY320954, respectively). These studies offer evidence for a novel class of pharmacophores for the 5-HT2 receptor family which show greater relative affinities for the 5-HT2A receptor subclass.
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PMID:A novel class of 5-HT2A receptor antagonists: aryl aminoguanidines. 884 11


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