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

In the present experiments we have investigated the possible coupling of 5-hydroxytryptamine (HT)3 receptors to the metabolism of phosphatidylinositol (PI) in the rat fronto-cingulate and entorhinal cortices, two brain regions with relatively high density of this receptor subtype. 5-HT dose-dependently increases PI turnover (20-80% increase above basal stimulation), with an EC50 of 0.5 and 0.3 microM for fronto-cingulate and entorhinal cortices, respectively. This effect was blocked by the selective 5-HT3 antagonists, BRL 43694 (granisetron), GR 38032F (ondansetron) and ICS 205-930. The selective 5-HT3 receptor agonists, 2-methyl-serotonin (2-Me-5-HT) and phenylbiguanide (PBG), mimicked the action of 5-HT and dose-dependently produced a significant increase in PI turnover (46-76% of the 5-HT response). The stimulatory action of 2-Me-5-HT and phenylbiguanide was blocked completely by granisetron, ondansetron and ICS 205-930 but not by other receptor antagonists such as (+/-)-pindolol (a beta, 5-HT1A and 5-HT1B receptor antagonist), methy-sergide (a 5-HT1 and 5-HT2 receptor antagonist), ritanserin (a 5-HT1C and 5-HT2 receptor antagonist), SR 95103 (gamma-aminobutyric acidA receptor antagonist), scopolamine (a muscarinic antagonist), (-)-eticlopride (a D2 receptor antagonist), SCH 23390 (a D1 5-HT2/1C receptor antagonist) and prazosin (an alpha-1 receptor antagonist). In addition, the stimulation of PI turnover by 2-Me-5-HT was antagonized stereospecifically by the 5-HT3 receptor blocker zacopride. Thus, only the active enantiomer (S)-zacopride, but not the less active enantiomer (R)-zacopride, was effective in blocking the 2-Me-5-HT-induced effect.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effect of 5-hydroxytryptamine3 receptor agonists on phosphoinositides hydrolysis in the rat fronto-cingulate and entorhinal cortices. 184 25

1. The effects of various 5-hydroxytryptamine (5-HT) receptor agonists were examined following unilateral infusion into the substantia nigra (SN) of the guinea-pig. 2. The 5-HT1 receptor agonists, 5-carboxamidotryptamine (5-CT) (2-25 micrograms), sumatriptan (10-25 micrograms) and RU24969 (25 micrograms) all induced a marked contralateral rotation. In contrast, the selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH DPAT, 10-25 micrograms) produced only a very small response, whilst the selective 5-HT1C/5-HT2 receptor agonist (+-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride ((+/-)-DOI) (25 micrograms) and the 5-HT3 receptor agonist, 2-methyl 5-HT (2-Me5-HT, 25 micrograms) were without effect. 3. The contralateral rotation induced by 5-CT (10 micrograms) was attenuated following pretreatment with the non-selective 5-HT1/5-HT2 receptor antagonists methiothepin (1 mg kg-1, s.c.) and metergoline (5-10 mg kg-1, s.c.) but not the 5-HT1C/5-HT2 antagonist ritanserin (1 mg kg-1, s.c.) or the 5-HT3 antagonist, ondansetron (0.5 mg kg-1, s.c.). An involvement of dopaminergic systems in the rotational response to 5-CT was implied by the antagonism of 5-CT-induced rotation by haloperidol (0.3 mg kg-1, s.c.). 4. At doses lower than those required to produce contralateral rotation, 5-CT (0.08-0.4 micrograms) and sumatriptan (2 micrograms) induced a small, but nonetheless consistent, ipsilateral rotation. 5. The data with agonists and antagonists taken together suggest that 5-CT-induced contralateral rotation may be mediated by 5-HTID receptor activation but definitive classification of the receptor will not be possible until selective 5-HTID-antagonists become available. This may therefore represent the first model to study this receptor subtype in vivo.
 ...
PMID:Evidence that the unilateral activation of 5-HT1D receptors in the substantia nigra of the guinea-pig elicits contralateral rotation. 184 63

Two subtypes of excitatory 5-hydroxytryptamine (5-HT) receptor, 5-HT1P and 5-HT3, are found on type 2-AH neurons of the guinea pig myenteric plexus. The 5-HT1P receptor mediates a slow and the 5-HT3 receptor a fast depolarization of these cells, however, the role of these receptors in the physiology of the gut is unknown. Renzapride (BRL 24924), a substituted benzamide, has previously been found to antagonize responses of myenteric neurons mediated by both 5-HT1P and 5-HT3 receptors. The effects on myenteric type 2-AH neurons of a structurally similar benzamide, zacopride, which unlike renzapride has S and R stereoisomers, were investigated to gain further insight into 5-HT receptor function. In contrast to renzapride, S-, but not R-zacopride, was found to mimic the 5-HT1P receptor-mediated slow response to 5-HT. Desensitization of 5-HT1P receptors with 5-HT inhibited slow depolarizing responses to S-zacopride, and desensitization with S-zacopride antagonized slow responses to 5-HT. Responses to S-zacopride were also inhibited by renzapride and the 5-HT1P receptor antagonist N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP). S-zacopride, like renzapride and 5-HT, presynaptically inhibited nicotinic fast excitatory postsynaptic potentials, an effect that can be mediated by 5-HT1P or 5-HT1A receptors. Both S and R stereoisomers of zacopride antagonized 5-HT3 receptor-mediated fast responses to 5-HT. Unlike 5-HTP-DP, neither zacopride or its stereoisomers nor renzapride inhibited the binding of 5-[3H]HT to 5-HT1P receptors. [3H]zacopride (5-10 nM) was found to bind to a site in the gut from which it could be displaced by a 1,000-fold excess of renzapride and S-zacopride (but not R-zacopride) greater than 5-HTP-DP much greater than the 5-HT3 receptor antagonist ICS 205-930. These observations suggest that, in addition to 5-HT3 receptors, there is a benzamide binding site on myenteric neurons that interacts with, but is distinct from, the 5-HT recognition site of 5-HT1P receptors. Benzamides may affect coupling of the 5-HT1P receptor to its effector.
 ...
PMID:Use of stereoisomers of zacopride to analyze actions of 5-hydroxytryptamine on enteric neurons. 198 11

This study examined whether the antinociception produced following the intrathecal (i.t.) administration of serotonin (5-hydroxytryptamine, 5-HT) and other 5-HT receptor agonists in a model of visceral pain that utilizes colorectal distension (CRD) as the noxious visceral stimulus is mediated through interaction with spinal 5-HT1, 5-HT2, or 5-HT3 receptor subtypes. CRD in conscious rats reliably elicits two pseudaffective reflexes: a vigorous pressor response and a visceromotor response. Antinociception is characterized by inhibition of both pseudaffective responses. The effects of 5-HT receptor agonists and antagonists on resting blood pressure were also examined. The i.t. administration of 5-HT resulted in a dose-dependent elevation of the visceromotor threshold and inhibition of the pressor response to CRD. The 5-HT1A receptor agonist 8-OH-DPAT, the 5-HT1B receptor agonist RU-24969, the 5-HT2 receptor agonists DOI, MK-212 and alpha-methyl-5-HT and the 5-HT3 agonist 2-methyl-5-HT all dose-dependently inhibited the pressor response and dose-dependently elevated the visceromotor threshold to noxious CRD. The rank order of potency of these agonists was the same for both pseudaffective responses to CRD: DOI greater than or equal to 8-OH-DPAT greater than or equal to MK-212 = RU-24969 greater than or equal to alpha-methyl-5-HT = 2-methyl-5-HT much greater than 5-HT. The antinociceptive effects of 5-HT, RU-24969, alpha-methyl-5-HT and DOI were antagonized by i.t. pretreatment with methysergide. Intrathecal pretreatment with ketanserin antagonized the antinociceptive effects of MK-212 and MDL-72222 antagonized the effects produced by 2-methyl-5-HT in response to CRD. The antinociceptive effects produced by 8-OH-DPAT were not antagonized by i.t. pretreatment with methysergide. These results demonstrate that 5-HT1, 5-HT2 and 5-HT3 receptors in the spinal cord mediate antinociception in response to noxious CRD in conscious rats.
 ...
PMID:Evidence that spinal 5-HT1, 5-HT2 and 5-HT3 receptor subtypes modulate responses to noxious colorectal distension in the rat. 201 33

The effects of serotonergic activation on cold-stimulated thyrotropin (TSH) and prolactin secretion were studied in male rats. Peripheral injections of both 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), a 5-HT1A receptor agonist, and 1-(3-chlorophenyl)piperazine (m-CPP), a 5-HT1 agonist, decreased TSH levels. The action of 8-OH-DPAT was antagonized by (+/-)-pindolol, which is known to have 5-HT1 antagonist activity, but not by metergoline or ketanserin. The action of m-CPP was antagonized by ketanserin but not by metergoline. TSH levels were not affected by a 5-HT3 receptor agonist, 2-methyl-5-HT, or by a 5-HT3 antagonist, MDL 72222. Infusion of 8-OH-DPAT into the anterior third ventricle increased TSH levels; 5-HT tended to increase TSH levels, but the effect was not significant. Inversely, infusion of 5-HT, 8-OH-DPAT or m-CPP into the posterior third ventricle decreased TSH levels. The action of 5-HT was counteracted by metergoline, ketanserin and (+/-)-pindolol. Unexpectedly, m-CPP infusion into the anterior third ventricle also inhibited TSH secretion. The prolactin-elevating effects of 5-HT, 8-OH-DPAT and m-CPP were neither consistent nor site-specific. In conclusion, stimulation of both 5-HT1 and 5-HT2 receptors may inhibit TSH secretion, but the exact mechanism underlying the site-dependent action of 5-HT and 8-OH-DPAT on TSH secretion remains to be identified.
 ...
PMID:Complex actions of serotonergic agonists on cold-stimulated TSH secretion in male rats. 214 94

In a previous study prolonged low-frequency muscle stimulation in the hind leg of the spontaneously hypertensive rat (SHR) was shown to induce a reduction in blood pressure (about 15 mmHg) that lasted for many hours. We showed in that study that endorphin and serotonin systems were involved. In the present study drugs with selective affinity for the serotonin (5-HT) receptors were used to analyse further the involvement of different serotonin systems. In one group of SHR, a prestimulatory dose of metitepine maleate (a 5-HT1 and 5-HT2 receptor antagonist) completely abolished the post-stimulatory depressor response. The long-lasting depressor response was still present, although less pronounced, after a bolus dose of the 5-HT2 blocking agent ritanserin (R 55667) at the start of stimulation. The 5-HT3 receptor antagonist ICS 205-930 did not influence the response at all, nor did the selective 5-HT1a receptor agonist 8-OH-DPAT enhance the depressor response. These results indicate that the reduction in blood pressure after muscle stimulation is mainly mediated by the 5-HT1 receptor.
 ...
PMID:Role of different serotonergic receptors in the long-lasting blood pressure depression following muscle stimulation in the spontaneously hypertensive rat. 214 73

The human saphenous vein preincubated with [3H]noradrenaline was used to determine the pharmacological properties of the release-inhibiting presynaptic serotonin (5-HT) receptor on the sympathetic nerves. The overflow of tritium evoked by transmural electrical stimulation (2 Hz) was concentration-dependently inhibited by drugs known to stimulate 5-HT receptors in the following rank order: oxymetazoline greater than or equal to 5-HT greater than 5-carboxamidotryptamine = 5-methoxytryptamine = sumatriptan greater than tryptamine greater than N,N(CH3)2-5-HT = yohimbine = 8-hydroxy-2-(di-n-propylamino)-tetraline. The potencies of these agonists in inhibiting overflow were significantly correlated with their affinities for 5-HT1B and 5-HT1D binding sites, but not with those for 5-HT1A or 5-HT1C binding sites. 5-Aminotryptamine, methysergide, ipsapirone, cyanopindolol, SDZ 21009 and metergoline dit not produce a significant inhibition. Metitepine and methysergide antagonized the inhibitory effect of 5-HT, whereas spiroxatrine, propranolol, ketanserin and ICS 205-930 did not. These data exclude the idea that the inhibitory presynaptic 5-HT receptor on the sympathetic nerves belongs to the 5-HT2 and 5-HT3 receptor class; the pattern of agonist potencies suggests that the receptor is very similar to the 5-HT1D receptor subtype.
 ...
PMID:Inhibition of noradrenaline release from the sympathetic nerves of the human saphenous vein via presynaptic 5-HT receptors similar to the 5-HT 1D subtype. 225 30

Evolutionary constant serotonin (5-HT) neuronal systems evolved along medial brain structures; yet, wide variations in functionality characterize serotonergic systems in mediating aggressive responses in species ranging from lobsters, ants, electric fish, and rodents to primates. So far, the attempts to correlate cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) levels with measures of aggression have revealed inverse, direct, or no correlations in different nonhuman primate species. It is difficult to harmonize the occasional correlations between CSF 5-HIAA and adaptive aggressive acts in nonhuman primates (a) with clinically diagnosed suicidal or impulsive individuals, and (b) with the biochemical, anatomical, and presumably functional differentiation of 5-HT pathways and receptor subtypes. Eltoprazine, a mixed 5-HT1A/B agonist, and meta-trifluoro-methylphenyl-piperazine HCl (TFMPP), a more selective 5-HT1B agonist, specifically decrease aggressive behavior in several animal species and situations in both sexes without detriment to other social, exploratory, or motoric activities. A definite role for 5-HT1A, 5-HT2, and 5-HT3 receptor subtypes in the mechanisms mediating aggressive behaviors has to await the development of selective agonists and antagonists, respectively.
 ...
PMID:Brain 5-HT and inhibition of aggressive behavior in animals: 5-HIAA and receptor subtypes. 248 73

The effects of eight serotonin (5-HT) receptor antagonists on the anorectic effect of d-fenfluramine (3.0 mg/kg, IP) were examined in a test of sweet mash consumption, using non-deprived male rats. d-Fenfluramine's effect was attenuated by the mixed 5-HT1/5-HT2 receptor antagonists, methiothepin and metergoline; by the 5-HT2 receptor antagonist ritanserin; and by (+/-)cyanopindolol, a mixed 5-HT1A/5-HT1B receptor antagonist. In contrast, d-fenfluramine's effect was not antagonised by the 5-HT2 receptor antagonists ketanserin and ICI 169 369; the 5-HT3 receptor antagonist ICS 205 930; or by xylamidine, a peripheral 5-HT receptor antagonist. In this feeding model, none of the 5-HT antagonists, when tested alone, had any effect to increase palatable food consumption. The pattern of results obtained strongly suggest that central 5-HT1 receptors play an important role in the mediation of d-fenfluramine-induced anorexia.
 ...
PMID:Evidence that d-fenfluramine anorexia is mediated by 5-HT1 receptors. 249 30

1. The aim of the present work was to characterize the presynaptic 5-HT receptors that mediate either the facilitation of the responses to nerve stimulation in the nictitating membrane of the cat or the inhibition of the responses to nerve stimulation in the guinea-pig atria. 2. In the nictitating membrane of the cat, the shift to the left in the frequency-response curves produced by 5-HT (0.1 microM) was prevented by the 5-HT3 receptor antagonists, metoclopramide (1 microM) and MDL 72222 (0.01 microM). 3. The facilitatory effect of 5-HT is also prevented by the 5-HT2 receptor antagonist, 0.01 microM ketanserin. Nevertheless, this drug reduced by itself the responses to both nerve stimulation and exogenous NA in the nictitating membrane. 4. In the guinea-pig isolated atria, the inhibitory effect of 5-HT on the chronotropic responses to cardioaccelerans nerve stimulation was mimicked by the mixed 5-HT1A + 5-HT1B + 5-HT1D receptor agonist 5-carboxamidotryptamine (5-CT 0.1 and 1 microM). The 5-HT1A receptor agonist 8-OH-DPAT (0.1 and 1 microM) did not modify the responses of the atria to the nerve stimulation. 5. The 5-HT2 receptor antagonists, ketanserin (0.01 and 0.1 microM) and cyproheptadine (1 microM), did not prevent the inhibitory effect of 5-HT in the guinea-pig atria. 6. The present results suggest that the facilitatory effects of 5-HT in the nictitating membrane of the cat are linked to the activation of 5-HT3 receptors whereas the inhibitory effects observed in the guinea-pig atria are mediated by 5-HT1-like receptors.
 ...
PMID:Different receptor subtypes mediate the dual presynaptic effects of 5-hydroxytryptamine on peripheral sympathetic neurones. 252 97


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>