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Query: UNIPROT:P46098 (5-HT3 receptor)
 2,290 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ionic currents induced by 5-hydroxytryptamine (5-HT) in cultured neuroblastoma N18 cells were studied using whole-cell voltage clamp. The response was blocked by 1-10 nM 5-HT3 receptor-specific antagonists MDL 7222 or ICS 205-930, but not by 1 microM 5-HT1/5-HT2 receptor antagonist spiperone or 5-HT2 receptor-specific antagonist ketanserin. These 5-HT3 receptors seem to be ligand-gated channels because the response (a) did not require internal ATP or GTP, (b) persisted with long internal dialysis of CsF (90 mM), A1F4- (100 microM), or GTP gamma S (100 microM), and (c) with ionophoretic delivery of 5-HT developed with a delay of less than 10 ms and rose to a peak in 34-130 ms. Fluctuation analysis yielded an apparent single-channel conductance of 593 fS. The relative permeabilities of the channel for a variety of ions were determined from reversal potentials. The channel was only weakly selective among small cations, with permeability ratios PX/PNa of 1.22, 1.10, 1.01, 1.00, and 0.99 for Cs+, K+, Li+, Na+, and Rb+, and 1.12, 0.79, and 0.73 for Ca2+, Ba2+, and Mg2+ (when studied in mixtures of 20 mM divalent ions and 120 mM N-methyl-D-glucamine). Apparent permeability ratios for the divalent ions decreased as the concentration of divalent ions was increased. Small monovalent organic cations were highly permeant. Large organic cations such as Tris and glucosamine were measurably permeant with permeability ratios of 0.20 and 0.08, and N-methyl-D-glucamine was almost impermeant. Small anions, NO3-, Cl-, and F-, were slightly permeant with permeability ratios of 0.08, 0.04, and 0.03. The results indicate that the open 5-HT3 receptor channel has an effective minimum circular pore size of 7.6 A and that ionic interactions in the channel may involve negative charges near the pore mouth.
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PMID:Ion permeation through 5-hydroxytryptamine-gated channels in neuroblastoma N18 cells. 228 32

The 5-HT3 receptor antagonists ICS 205-930 and zacopride attenuated cocaine-induced locomotor activity in C57BL/6ByJ mice. In contrast, the aselective 5-HT1 and 5-HT2 receptor antagonist, methysergide did not affect the response to cocaine. The effect of the 5-HT3 receptor antagonists was not due to general sedation, because zacopride did not alter the locomotor response to caffeine.
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PMID:5-HT3 receptor antagonists attenuate cocaine-induced locomotion in mice. 228 34

1. Mice were isolated for 7-9 days. An isolated mouse and a mouse reared in group showed a difference in their behaviour when observed together under an inverted beaker. The isolated mouse makes one half escape attempts in regard to the grouped mouse. This is considered as a social behavioural deficit. 2. 1- 3-(trifluoromethyl)phenyl piperazine (TFMPP), 1-(3-chlorophenyl)piperazine (m-CPP) and 5-methoxy-3 (1,2,3,6-tetrahydropyridin-4-yl) 1-H indole (RU-24969) activating preferentially the 5-HT1B receptors increased the number of escape attempts of the isolated mice up to the level of grouped mice. 3. Penbutolol, a beta-blocking drug acting also at 5-HT1 receptors, devoid of effect when given alone, antagonized significantly and dose-dependently the effects of TFMPP, m-CPP and RU-24969. 4. The interaction between TFMPP and five various serotonin antagonists was examined. Neither the 5-HT2 receptor antagonist ritanserine, the 5-HT3 receptor antagonist ICS 205-930, the 5-HT1C receptor antagonists mianserin and cyproheptadine antagonized the effect of TFMPP. The neuroleptic spiperone decreased by itself the number of escape attempts and opposed the TFMPP effect. 5. Taken together, these results suggest that the isolation-induced social behavioural deficit may be considered as a behavioural model responsive to 5-HT1B agonists.
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PMID:Improvement of the isolation-induced social behavioural deficit involves activation of the 5-HT1B receptors. 230 Jun 82

1. The effects of 5-hydroxytryptamine (5-HT) and the selective 5-HT3 receptor agonist 2-methyl-5-HT were examined on the tracheal vasculature in anaesthetised, paralysed and artificially ventilated sheep. The cranial tracheal arteries were perfused with blood at constant flow and perfusion pressure was measured. 5-HT and 2-methyl-5-HT were injected into the arterial perfusate. Changes in tracheal smooth muscle tone were also measured. 2. 5-HT contracted the tracheal smooth muscle. This contraction was not affected by the 5-HT2 receptor antagonist ketanserin, but was blocked by the combined '5-HT1-like' and 5-HT2 receptor antagonist methysergide. 2-methyl-5-HT had no effect on the tracheal smooth muscle. 3. 5-HT had a complex action on the tracheal vasculature producing either a biphasic change (vasoconstriction followed by dilatation) or just a constriction. 2-methyl-5-HT had a weak vasoconstrictor effect. 4. The vasoconstrictions produced by 5-HT and 2-methyl-5-HT were blocked by ketanserin. The vasodilatation produced by 5-HT was resistant to ketanserin but was antagonised by methysergide. 5. Thus 5-HT contracts the tracheal smooth muscle of sheep by stimulating '5-HT1-like' receptors. 5-HT constricts the tracheal vascular bed by stimulating 5-HT2 receptors or dilates the vascular bed by stimulating '5-HT1-like' receptors. 5-HT3 receptors appear not to be involved in the responses of the tracheal vasculature or smooth muscle to 5-HT.
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PMID:Receptors mediating the effects of 5-hydroxytryptamine on the tracheal vasculature and smooth muscle of sheep. 233 72

The present studies demonstrate the presence of specific [3H]GR65630 binding sites within the human brainstem using the techniques of in vitro receptor autoradiography and ligand binding to homogenates. Autoradiography revealed the greatest accumulation of specific binding in the area postrema and subpostrema (AP/ASP). A lower level of specific binding was identified in the nucleus tractus solitarius (excluding area subpostrema). No specific binding was evident in the remainder of the hindbrain at this level. Discrete dissection followed by ligand binding to homogenates revealed that the specific binding of [3H]GR65630 (defined by the presence of 30 microM metoclopramide) was differentially distributed with highest levels in the AP/ASP (112.1 fmol/mg protein) and lower levels in the dorsal vagal complex (nucleus tractus solitarius--excluding the area subpostrema--dorsal motor nucleus of the vagus and hypoglossal nucleus) (DVC) and olivary nucleus (ON) (22.9 and 3.9 fmol/mg, respectively). No specific binding was detectable in the reticular formation (RF) located ventral to the dorsal vagal complex. The specific [3H]GR65630 binding site was pharmacologically similar to the 5-HT3 receptor since the potent and selective 5-HT3 receptor antagonists ICS 205-930 and zacopride (100 nM) and the agonist 5-HT (10 microM) inhibited binding to the same extent as metoclopramide in each of the individual areas (90, 60 and 20% in the AP/ASP, DVC and ON, respectively). The 5-HT1-like and 5-HT2 receptor antagonist methysergide (10 microM) failed to compete for the binding site. 5-HT3 receptor recognition sites within the AP/ASP and the DVC may be functionally involved in the ability of 5-HT3 receptor antagonists to control emesis.
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PMID:Identification and distribution of 5-HT3 recognition sites within the human brainstem. 233 96

The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic adenosine monophosphate, 5-hydroxytryptamine (5-HT), prostaglandins, and the function of neuronal structures have been implicated in the pathogenesis of cholera. To elucidate the action of 5-HT in mediating cholera secretion, in vivo experiments were performed in the rat jejunum. The inhibitory effects of the 5-HT2 receptor antagonist ketanserin and the 5-HT3 receptor antagonist ICS 205-930 were studied in cholera toxin- and 5-HT-induced fluid secretion. Both ketanserin and ICS 205-930 dose-dependently but only partially reduced the secretory effect of cholera toxin. The combination of the two blockers totally abolished cholera toxin-induced secretion without any influence on cholera toxin-induced increase in cyclic adenosine monophosphate. Prostaglandin E2- and bisacodyl-induced secretion was not affected by the combined administration of 5-HT2 and 5-HT3 antagonists. The present results provide evidence for an important role of 5-HT in cholera toxin-induced secretion. The data suggest a model in which cholera toxin may initiate the release of 5-HT from enterochromaffin cells. 5-Hydroxytryptamine may then cause prostaglandin E2 formation via 5-HT2 receptors and activation of neuronal structures via 5-HT3 receptors. These two effects may finally lead to the profuse fluid secretion which can be totally blocked by the combination of a 5-HT2 blocker and a 5-HT3 blocker.
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PMID:5-HT2 and 5-HT3 receptor subtypes mediate cholera toxin-induced intestinal fluid secretion in the rat. 234 45

The effects of 5-hydroxytryptamine (5-HT), the 5-HT1-like receptor agonist 5-carboxamidotryptamine and the 5-HT3 receptor agonist 2-methyl-5-hydroxytryptamine were studied on circular muscle strips of the canine terminal ileum and ileocolonic junction. Serial administration of 5-HT or of 5-carboxamidotryptamine induced slow tonic contractions that at higher concentrations of 5-HT (10(-4)-3 x 10(-4] were preceded by an initial relaxation and a fast phasic contraction. The concentration-response curves to both agonists were competitively shifted to the right by the mixed 5-HT1/5-HT2 receptor antagonist methysergide. The initial relaxation and fast phasic contraction were inhibited by the 5-HT3 receptor antagonist ICS 205-930 and tetrodotoxin. Atropine blocked the fast phasic contraction, but enhanced the relaxation. During acetylcholine-induced contractions, 5-HT and 2-methyl-5-hydroxytryptamine (greater than or equal to 10(-5) M), but not 5-carboxamidotryptamine, evoked relaxations that were blocked by ICS 205-930 and tetrodotoxin, but not by adrenoceptor antagonists. Thus, in the canine terminal ileum and ileocolonic junction, 5-HT stimulates neuronal 5-HT3 receptors and excitatory 5-HT1-like receptors located on smooth muscle. Stimulation of the 5-HT3 receptors results in an acetylcholine-mediated contraction and a relaxation mediated by an as yet unknown nonadrenergic noncholinergic neurotransmitter.
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PMID:Pharmacological characterization of 5-hydroxytryptamine receptors in the canine terminal ileum and ileocolonic junction. 238 90

The selective "5-HT1-like" receptor agonist 5-carboxamidotryptamine (5-CT, 0.2-1.6 micrograms/kg bolus i.v.), serotonin (5-HT, 3-10 micrograms/kg), and phenylbiguanide (10-40 micrograms/kg) all elicited the "Bezold-Jarisch-like" bradycardia reflex in conscious rabbits. This reflex was antagonised by the 5-HT3 receptor antagonist, MDL 72222. After autonomic blockade (mecamylamine), 5-CT and 5-HT infusion (i.v.) caused renal artery spasm (Doppler flowmeter) that was antagonised by ketanserin, a 5-HT2-receptor antagonist. Both 5-CT and 5-HT caused 5-HT1-like receptor mediated increases in hindquarter conductance that were unaltered by ketanserin (0.5 mg/kg). The anomalous 5-HT3 and 5-HT2 receptor actions of 5-CT were completely prevented by 16 h pretreatment with reserpine (5 mg/kg) that lowered total serum serotonin to less than 3% of normal but did not reduce the cardiovascular actions of 5-HT. Fluoxetine (1 mg/kg i.v.), an inhibitor of 5-HT uptake into platelets, significantly attenuated the Bezold-Jarisch-like reflex evoked by 5-CT but not by 5-HT. These studies suggest that 5-CT is carried into platelets where it releases 5-HT. This illustrates how apparent receptor selectivity asserted in in vitro assays can be destroyed in vivo.
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PMID:5-carboxamidotryptamine elicits 5-HT2 and 5-HT3 receptor-mediated cardiovascular responses in the conscious rabbit: evidence for 5-HT release from platelets. 247 Sep 92

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.
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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.
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PMID:Different receptor subtypes mediate the dual presynaptic effects of 5-hydroxytryptamine on peripheral sympathetic neurones. 252 97


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