Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P46098 (5-HT3 receptor)
 2,290 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intra- and extracellular recordings from the in vitro rat hippocampal slice preparation have been used to investigate the influence of serotoninergic, adrenergic and cholinergic receptor antagonists on the excitability of CA1 pyramidal neurones. The serotonin receptor antagonist 4-amino-N-(1-azabicyclo[2.2.2]oct-3yl)-5-chloro-2- methoxybenzamide(E)-2-butenedioate (zacopride, 100 microM) produced multiple population spikes on the orthodromically evoked field potential, in contrast to the lack of effect of another serotonin antagonist 1 alpha H,3 alpha,5 alpha H-tropan-3-yl-3,5-dichlorobenzoate (MDL 72222, 30 microM), as well as the cholinergic antagonists atropine (10 microM) and hexamethonium (100 microM) and the noradrenergic antagonist atenolol (10 microM). Monosynaptic inhibitory postsynaptic potentials (IPSPs) recorded in the presence of the glutamatergic antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM) and ketamine (50 microM) were recorded from CA1 pyramidal neurones. Zacopride (100 microM) and MDL 72222 (30 microM) both reduced the isolated IPSP to 54 +/- 9% (n = 8) and 78 +/- 4% (n = 3), respectively. Neither of the cholinergic antagonists had any effect, while atenolol reduced the IPSP to 87 +/- 3% (n = 7) of the control IPSP. We propose that the difference in action of zacopride and MDL 72222 on the field potentials is due to zacopride activating postsynaptic 5HT4 receptors on the pyramidal neurone, thereby reducing a Ca(2+)-activated K(+)-conductance. This, in combination with a 5HT3 receptor-mediated reduction in gamma-aminobutyric acid (GABA)-ergic inhibition, leads to an increase in pyramidal cell excitability evident as epileptic field potentials.
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PMID:Serotoninergic modulation of excitability in area CA1 of the in vitro rat hippocampus. 857

Serotonin (5-HT) receptors can be classified into at least three, possibly up to seven, classes of receptors. They comprise the 5-HT1, 5-HT2, and 5-HT3 classes, the "uncloned' 5-HT4 receptor and the recombinant receptors 5-ht5, 5-ht6 and 5-ht7. We investigated the role of different serotonin receptor types in a neuroendocrine response to the activation of the serotonergic system. Female immature rats were chosen as an experimental model as it has been shown that during the 3rd week of life, and not at later developmental stages, 5-hydroxytryptophan (5-HTP, a serotonin precursor) induces gonadotropin release in females and not in males. Besides, at this age, serotonin releases prolactin in both sexes. 5-HTP (50 mg/kg) released prolactin, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) as expected. Ketanserin (5-HT2A antagonist) and methysergide (5-HT2C antagonist) blocked 5-HTP-induced prolactin release, but did not block the LH or FSH responses. Ondansetron (5-HT3 receptor antagonist) did not modify prolactin response to 5-HTP, whereas it blocked 5-HTP-induced LH and FSH release. Propranolol (5-HT1 and beta-adrenergic antagonist) blocked prolactin, LH and FSH release induced by 5-HTP. The 5-HT2C agonist 1-(3-chlorophenyl)piperazine dihydrochloride released prolactin, without modifying LH or FSH release. Methyl-quipazine and phenylbiguanide (5-HT3 agonists) increased both LH and FSH levels, without altering prolactin secretion. The present experiments indicate that serotonin acting at the 5-HT3 receptor mediates LH and FSH release in infantile female rats, whereas 5-HT2C or 2A receptor types participate in the release of prolactin at this age. 5-HT1 receptor type may be involved in the release of the three hormones, though a beta-adrenergic component of the response cannot be discarded.
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PMID:Different serotonin receptor types participate in 5-hydroxytryptophan-induced gonadotropins and prolactin release in the female infantile rat. 873 78

The serotonin 5-HT3 receptor is unique among the seven serotonin receptor "families" that have been recognized so far. It functions not as a G-protein coupled but as a direct ion channel gated receptor. Because of the varied neural functions linked to this receptor, intensive research interest has developed in recent years about its basic and clinical pharmacology, which are summarized in this review. Some new agonists and many new antagonists have been developed. These agents have a useful role as selective pharmacologic research probes, and some of them can be used therapeutically as potent and selective anti-nausea and antiemetic drugs, particularly in patients undergoing cancer chemotherapy treatment or general anesthesia procedures. Potential applications of these agents include the treatment of some behavioral disorders in mental disease, drug addiction, and certain types of pain syndromes.
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PMID:5-HT3 receptors: pharmacologic and therapeutic aspects. 878 44

The effects of several metals on the serotonin receptor-channel complex were studied using mouse neuroblastoma N1E-115 cells which are known to be endowed with the 5-HT3 subclass of the receptor. The whole-cell patch clamp technique was used to record currents induced by serotonin at a concentration of 3 microM which was equivalent to the apparent dissociation constant. Methylmercury and mercuric chloride suppressed serotonin-induced currents irreversibly, with a 50% suppression being observed at concentrations of 3 microM and 2 microM, respectively. Lead and zinc suppressed the current with IC50S of 80 microM and 50 microM, respectively, and the effects of both metals were reversible after washing with metal-free solution. Lanthanum also suppressed the current with an IC50 of 10 microM, and the effect was partially reversible. Cadmium and cobalt augmented serotonin-induced currents slightly but consistently at a concentration of 100 microM, and the effect was reversible. Aluminum at 100 microM, had no effect on serotonin-induced currents. It was concluded that the 5-HT3 receptor is endowed with a unique property with respect to the actions of metals which is not shared by some other ligand-gated and voltage-gated ion channels.
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PMID:Modulation of serotonin-induced currents by metals in mouse neuroblastoma cells. 887 Sep 59

Several human Mendelian diseases, including the long-QT syndrome, malignant hyperthermia, and episodic ataxia/myokymia syndrome, have recently been demonstrated to be due to mutations in ion channel genes. Systematic mapping of ion channel genes may therefore reveal candidates for other heritable disorders. In this study, the GenBank and dbEST databases were used to identify members of several ion channel families (voltage-gated calcium and sodium, cardiac chloride, and all classes of potassium channels). Genes and ESTs without prior map localization were identified based on GDB and OWL database information and 15 genes and ESTs were selected for mapping. Of these 15, only the serotonin receptor 5HT3R had been previously mapped to a chromosome. A somatic cell hybrid panel (SCH) was screened with an STS from each gene and, if necessary the results verified by a second SCH panel. For three ESTs, rodent derived PCR products of the same size as the human STS precluded SCH mapping. For these three, human P1 clones were isolated and the genomic location was determined by metaphase FISH. These genes and ESTs can now be further evaluated as candidate genes for inherited cardiac, neuromuscular and psychiatric disorders mapped to these chromosomes. Furthermore, the ESTs developed in this study can be used to isolate genomic clones, enabling the determination of each transcript's genomic structure and physical map location. This approach may also be applicable to other gene families and may aid in the identification of candidate genes for groups of related heritable disorders.
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PMID:Chromosomal localization of 15 ion channel genes. 903 51

The serotonergic system appears to play a role in behaviors that involve a high cognitive demand and in memory improvement or recovery from impaired cognitive performance, as made evident after administration of serotonin 5-HT2A/5-HT2C or 5-HT4 receptor agonists or 5-HT1A or 5-HT3 receptor antagonists. These serotonin receptor subtypes are localized on 'cognitive' pathways, with the hippocampus and frontal cortex as the main target structures. A better understanding of the role played by these and other serotonin receptor subtypes in cognition is likely to result from the recent availability of new specific ligands and new molecular tools, such as gene knock-out and transgenic mice.
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PMID:Serotonin receptors in cognitive behaviors. 914 56

The genes responsible for hereditary paragangliomas (glomus tumors, MIM No. 168000) have been mapped to two distinct loci on the long arm of chromosome 11. Most of the informative families appear to be linked to the distal locus on chromosome 11q23 (PGL1), which has been previously confined to a 2-cM interval by haplotype analysis in an extended Dutch pedigree. To facilitate the identification of the PGL1 disease gene, we constructed an approximately 4-Mb ordered clone contig map of Sequence tagged sites, expressed sequence tags (ESTs), and known genes that spans the PGL1 critical region on chromosome 11q23. Among 29 new positional candidate ESTs, only two (EST100999 and EST241777) mapped within the PGL1 critical region. We further characterized the genomic organization of the promyelocytic leukemia zinc finger (PLZF) gene that maps within the PGL1 critical region and physically excluded the serotonin receptor type 3 (5HT3R) gene. Finally, we identified a common, silent, single-base substitution polymorphism in the 5HT3R gene and characterized the allele sets of two new highly polymorphic microsatellite repeats within the PGL1 critical region.
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PMID:A high-resolution STS, EST, and gene-based physical map of the hereditary paraganglioma region on chromosome 11q23. 929 38

Little is definitively known of the identity or actions of neurotransmitters utilized within mammalian taste buds. Serotonin has been immunocytochemically localized to taste cells of several species but its physiological actions are unknown. Using whole-cell patch clamp recordings on dissociated posterior rat taste cells, data are presented to suggest that exogenously applied serotonin inhibits a calcium-activated potassium current by up to 50%. This current, best visualized at depolarized holding potentials, is both apamin- and charybdotoxin-sensitive. Approximately 60% of the tested taste cells were serotonin sensitive. This inhibition was mimicked by N-(3-trifluoromethylphenyl)piperazine (TFMPP), a general serotonin receptor agonist, by 8-hydroxy-dipropylaminotetralin (8-OH-DPAT), a selective 5-HT1A receptor agonist, but not by phenylbiguanide, a 5-HT3 receptor agonist. These are the first data to establish a physiological effect of serotonin on mammalian taste cells.
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PMID:Serotonin inhibits calcium-activated K+ current in rat taste receptor cells. 935 53

The clinical use of currently available drugs acting at the 5-HT4 receptor has been hampered by their lack of selectivity over 5-HT3 binding sites. For this reason, there is considerable interest in the medicinal chemistry of these serotonin receptor subtypes, and significant effort has been made towards the discovery of potent and selective ligands. Computer-aided conformational analysis was used to characterize serotoninergic 5-HT3 and 5-HT4 receptor recognition. On the basis of the generally accepted model of the 5-HT3 antagonist pharmacophore, we have performed a receptor mapping of this receptor binding site, following the active analog approach (AAA) defined by Marshall. The receptor excluded volume was calculated as the union of the van der Waals density maps of nine active ligands (pKi > or = 8.9), superimposed in pharmacophoric conformations. Six inactive analogs (pKi < 7.0) were subsequently used to define the essential volume, which in its turn can be used to define the regions of steric intolerance of the 5-HT3 receptor. Five active ligands (pKi > or = 9.3) at 5-HT4 receptors were used to construct an antagonist pharmacophore for this receptor, and to determine its excluded volume by superimposition of pharmacophoric conformations. The volume defined by the superimposition of five inactive 5-HT4 receptor analogs that possess the pharmacophoric elements (pKi < or = 6.6) did not exceed the excluded volume calculated for this receptor. In this case, the inactivity may be due to the lack of positive interaction of the amino moiety with a hypothetical hydrophobic pocket, which would interact with the voluminous substituents of the basic nitrogen of active ligands. The difference between the excluded volumes of both receptors has confirmed that the main difference is indeed in the basic moiety. Thus, the 5-HT3 receptor can only accommodate small substituents in the position of the nitrogen atom, whereas the 5-HT4 receptor requires more voluminous groups. Also, the basic nitrogen is located at ca. 8.0 A from the aromatic moiety in the 5-HT4 antagonist pharmacophore, whereas this distance is ca. 7.5 A in the 5-HT3 antagonist model. The comparative mapping of both serotoninergic receptors has allowed us to confirm the three-component pharmacophore accepted for the 5-HT3 receptor, as well as to propose a steric model for the 5-HT4 receptor binding site. This study offers structural insights to aid the design of new selective ligands, and the resulting models have received some support from the synthesis of two new active and selective ligands: 24 (Ki(5-HT3) = 3.7 nM; Ki(5-HT4) > 1000 nM) and 25 (Ki(5-HT4) = 13.7 nM; Ki(5-HT3) > 10,000 nM).
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PMID:Comparative receptor mapping of serotoninergic 5-HT3 and 5-HT4 binding sites. 949 51

In the mid-1980s it was discovered that serotonin (5-hydroxytryptamine; 5-HT) was at least partially responsible for producing chemotherapy-induced nausea and vomiting. It was therefore realised that serotonin receptor blockade with serotonin 5-HT3 receptor antagonists could inhibit chemotherapy-induced nausea and vomiting. 5-HT3 antagonists have different chemical structures and receptor binding affinity. Granisetron, dolasetron and its major metabolite are pure 5-HT3 antagonists, while ondansetron and tropisetron are weak antagonists at the 5-HT4 receptor. Ondansetron has also been demonstrated to bind at other serotonin receptors and to the opioid mu receptor. The half-lives of granisetron, tropisetron and the active metabolite of dolasetron are 2 to 3 times longer than that of ondansetron. These observations initially suggested that more frequent ondansetron administration would be required; however, it has now been shown that receptor blockade does not correlate with elimination half-life and all 5-HT3 antagonists can be effectively administered once daily. Clinical trials have been conducted that directly compare the 5-HT3 antagonists. To compare these studies, it is necessary to assess trial design, including known risk factors for the development of chemotherapy-induced nausea and vomiting, and response criteria. Stratification for risk factors, use of strict efficacy criteria and randomisation to a blinded trial using an appropriate comparative regimen are essential for a well designed antiemetic trial. Comparative clinical trials using various doses, routes and regimens of administration have been conducted with 5-HT3 antagonists. Despite some trial design shortcomings, most of the studies show equal efficacy between the agents, especially in moderately emetogenic chemotherapy and mild, infrequently occurring adverse effects. The addition of steroids also appears to improve outcome. However, since many doses and regimens of ondansetron were used, further study is needed to determine the optimal regimen. The efficacy of 5-HT3 antagonists in controlling delayed nausea and vomiting from chemotherapy is less well studied. Further, there is no good scientific rationale for the use of 5-HT3 antagonists in controlling delayed nausea and vomiting since serotonin has not been shown to be released during the delayed phase. In fact, most studies show no benefit or modest benefit of 5-HT3 antagonists over placebo. Because the 5-HT3 antagonists perform similarly in the clinical setting, pharmacological differences do not seem to translate into therapeutic differences. There is also no appreciable difference in the incidence or severity of adverse effects among the 5-HT3 antagonists. Determination of clinical use may then be driven by cost.
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PMID:5-HT3 receptor antagonists for the prevention of chemotherapy-induced nausea and vomiting. A comparison of their pharmacology and clinical efficacy. 950 40


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