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)

Serotonin (5-HT) stimulates phosphoinositide (PI) turnover in rat fronto-cingulate cortical slices and is probably mediated through the activation of both 5-HT2 and 5-HT3 receptors. We have extended these findings and have assessed whether the increased stimulation of PI turnover is secondary to 5-HT stimulated arachidonate metabolism or to the release of another neurotransmitter. Incubation of the cortical slices by the two 5-HT3 receptor agonists, 2-methyl-serotonin (2-Me-5-HT) and phenylbiguanide (PBG), significantly decreases serotonin-stimulated phosphoinositide turnover, indicating that activation of 5-HT3, receptors by 2-Me-5-HT and PBG caused the desensitized PI hydrolysis to 5-HT. Indomethacin did not affect the increased PI hydrolysis induced by 5-HT, 2-Me-5-HT and PBG, suggesting that neither cyclooxygenase nor lipoxgenase activity is required for the PI response and that it is independent of arachidonic acid metabolism. The stimulation in PI turnover induced by 5-HT and the 5-HT3 receptor agonists was not potentiated by proteinase inhibitors suggesting that the release of a peptide neurotransmitter is not involved in the PI response. In addition, the effects of 5-HT, 2-Me-5-HT and PBG on PI turnover are additive to the effect of KCl and veratrine. In conclusion, our results indicate that the action of 2-Me-5-HT and PBG on PI turnover is direct.
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PMID:Biochemical characterization of phosphoinositide hydrolysis stimulated by 5-HT3 receptor agonists. 136 96

1. Using grease-gap recordings from the isolated superior cervical ganglion of mouse, rat and guinea-pig, we have compared the depolarization evoked by 5-hydroxytryptamine (5-HT) with that evoked by the selective 5-HT3 receptor agonist 2-methyl-5-HT (2-Me-5-HT). 2. The maximum depolarization induced by 2-Me-5-HT was smaller than that induced by 5-HT in all three species, and particularly in the guinea-pig. 3. The 5-HT2 receptor antagonist ketanserin (1 microM) caused a clear rightward shift of the dose-response curve to 5-HT on the guinea-pig ganglion, but not on the mouse or rat ganglion. Spiperone (0.03 microM) had a quantitatively similar action to ketanserin (0.1 microM) on the 5-HT dose-response curve of the guinea-pig ganglion. Ketanserin had no significant effect on the dose-response curve to 2-Me-5-HT on any of these ganglia. 4. Using 2-Me-5-HT as the agonist, we determined the pA2 values for two 5-HT3 receptor antagonists. The potency of ICS 205-930 varied by approximately 100 fold between the species and that of (+)-tubocurarine varied by over 1000 fold. The differences in the pA2 values of these compounds varied independently among the species. 5. We conclude that 5-HT3 receptors are present on the superior cervical ganglion from the rat, mouse and guinea-pig, but these receptors may be pharmacologically distinct from each other. In addition, the depolarization of the guinea-pig superior cervical ganglion by low concentrations of 5-HT is largely mediated by ketanserin-sensitive receptors.
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PMID:Evidence that the 5-HT3 receptors of the rat, mouse and guinea-pig superior cervical ganglion may be different. 136 27

The availability of radiolabelled ligands selective for various putative neurotransmitter receptor sites and the development of quantitative autoradiography has led to a greater understanding of the neuronal pathway and receptor subtypes involved in the vomiting reflex induced by various mechanisms both within the central nervous system and the periphery. Receptors for acetylcholine, dopamine, histamine and serotonin have been detected in a number of brain regions associated with the vomiting reflex, and provide a rational basis for the antiemetic action of drugs that inhibit receptor subtypes for these neurotransmitters. The basis of the antiemetic action of other drugs such as dexamethasone and the cannabinoids is still obscure. Some drugs act on more than 1 receptor subtype. Metoclopramide may inhibit both dopamine D2- and 5-HT3 receptors in producing its antiemetic effect. Both metoclopramide and domperidone appear to have additional peripheral actions that contribute to their effectiveness. The cannabinoids are effective in cytotoxic-induced vomiting, perhaps acting via endorphin receptors or by inhibiting prostaglandin synthesis. The effectiveness of 5-HT3 receptor antagonists may depend on the block of both central and peripheral neuronal 5-HT3 receptors. Vomiting constitutes a major disadvantage to the use of many drugs; vomiting induced by aminoglycoside antibiotics appears to be due to ototoxicity and is relieved by histamine H1-receptor antagonists. The protracted vomiting associated with the use of some cytotoxics in cancer chemotherapy may involve psychic components, the chemoreceptor trigger zone and peripheral sensory neurons. Both 5-HT3 and dopamine D2-receptor antagonists exert some control, the former being more effective with cytotoxics of high emetogenic potential, such as cisplatin. Serotonin 5-HT3 receptor antagonists or high doses of metoclopramide in combination with anxiolytics and steroids as well as greater attention to pharmacokinetic profiles of the drugs involved would appear to offer improved control. The use of dopamine receptor antagonists in controlling emesis induced by dopamine agonists used in Parkinson's disease poses theoretical problems which can be overcome by using drugs with selectivity for the chemoreceptor trigger zone, such as domperidone or metoclopramide. However, higher doses of these drugs may produce some impairment of therapeutic responses to the agonists. Muscarinic and nicotinic agonists currently under investigation in Alzheimer's disease pose another therapeutic dilemma as emesis is due to a central action of these compounds. Several sites may be involved including the chemoreceptor trigger zone and frontal lobes. Opiates may act through dopamine receptors or mu-receptors on dopaminergic nerves, but serotonergic mechanisms may also be involved in the action of some opiates.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pharmacological agents affecting emesis. A review (Part I). 137 16

Part I of this article reviewed the pathophysiology of emesis, and its pharmacological treatment. Drug-induced vomiting was also discussed. In the second part of the review, other common causes of vomiting are considered. The basis of the use of antiemetics in morning sickness and migraine is still obscure; for the latter, serotonin 5-HT1 receptor agonists, 5-HT3 receptor antagonists and dopamine D2 receptor antagonists are effective. For motion sickness, control can be achieved with various antagonists of muscarinic or histamine H1-receptors. Centrally active adrenoceptor agonists in combination with a muscarinic antagonist or H1-receptor antagonist may offer better control of motion sickness and its associated symptoms than either antagonist alone; based on clinical studies, postoperative vomiting after opiate administration appears to be controlled by blocking dopamine D2, histamine H1- or muscarinic receptors. Radiation therapy appears to be similar to cytotoxic therapy in that the mediators produced or released by radiation activate both peripheral and central sites involved in the vomiting reflex. Blockade of dopamine D2 and 5-HT3 receptors may be effective.
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PMID:Pharmacological agents affecting emesis. A review (Part II). 137 13

The ability of 5-HT3 receptor agonists to modulate the resting efflux or K(+)-evoked release of [3H]5-HT from superfused synaptosomes from the spinal cord of the rat was investigated. Phenylbiguanide did not alter the resting efflux of [3H]5-HIAA or [3H]5-HT or modify the K(+)-evoked release of [3H]5-HT. 2-Methyl-5-HT (10 microM) caused an increase in resting efflux of [3H]5-HIAA, an effect that was blocked by the inhibitor of the uptake of 5-HT fluoxetine. No effect on K(+)-evoked release of tritium was observed. Bufotenine (100-1000 nM) increased the resting efflux of [3H]5-HT and [3H]5-HIAA. These effects were not antagonized by the 5-HT3 antagonist ICS 205-930 but were antagonized by fluoxetine. The drug ICS 205-930 (1 microM) did not alter resting efflux or block the ability of serotonin (30 and 100 nM) to decrease K(+)-evoked release of tritium. Quipazine, a potent antagonist of peripheral 5-HT3 receptors (subnanomolar concentrations), was also unable to alter resting or K(+)-evoked release of [3H]5-HT. It did, however, attenuate the inhibitory effect 5-HT on K(+)-evoked release. The concentrations required were in the micromolar range, consistent with the ability of the drug to antagonize the 5-HT1B autoreceptor. These results support the idea that 5-HT3 receptors do not act as nerve terminal autoreceptors in the spinal cord of the rat.
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PMID:5-HT3 receptors are not involved in the modulation of the K(+)-evoked release of [3H]5-HT from spinal cord synaptosomes of rat. 138 44

Preclinical studies suggest that 5-HT3 antagonists modulate dopamine-mediated responses in the limbic system and may therefore have a therapeutic role in psychiatry. We have examined the effect of ondansetron, a specific 5-HT3 antagonist, on the psychological and psychomotor changes induced by amphetamine in human volunteers. Nine healthy males took part in this double-blind placebo-controlled balanced-crossover study. Each subject received one of three treatments in a randomised manner: (a) placebo/placebo; (b) placebo/amphetamine (15 mg); (c) ondansetron (4 mg)/amphetamine (15 mg). Subjects were assessed for self-ratings of hunger, mood, energy, alertness, restlessness, irritability, and asked to rate the abnormality of their overall subjective state. In addition, systolic blood pressure, and performance on psychomotor tests were repeatedly assessed. Although amphetamine did not cause any significant changes in self-rating of mood, energy, alterness, restlessness or irritability, it induced a significant increase in self-ratings for overall subjective state, and a significant decrease in self-ratings of hunger. Amphetamine also caused an increase in systolic blood pressure and a decrease in the mean time taken to complete the psychomotor tests. Pretreatment with ondansetron attenuated the effects of amphetamine on hunger and subjective state, but not on blood pressure or psychomotor performance tests. These findings suggest that in humans 5-HT3 receptor antagonists may partially modify the subjective effects of amphetamine, and are in keeping with results from animal studies that 5-HT3 receptor antagonists might affect neurotransmission within mesolimbic brain regions. However, it was not possible to exclude a pharmacokinetic interaction to explain the effects of ondansetron.
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PMID:Ondansetron, a 5-HT3 receptor antagonist, partially attenuates the effects of amphetamine: a pilot study in healthy volunteers. 138 3

1. An excitatory response to 5-hydroxytryptamine (5-HT) was measured from the afferent vagus nerve of anaesthetized rats. Measurements were determined by an extracellular recording from the whole nerve. 2. Intravenous bolus injection of 5-HT (1.56-100 micrograms kg-1) evoked a dose-dependent excitation of afferent vagus nerve activity. This response was blocked not only by a selective 5-HT3 receptor antagonist, GR38032F (10 and 100 micrograms kg-1), but also by a 5-HT2 receptor antagonist, ketanserin (10 and 100 micrograms kg-1). 3. Both a 5-HT3 receptor agonist, 2-methyl-5-HT (3.12-100 micrograms kg-1), and a 5-HT2 receptor agonist, alpha-methyl-5-HT (3.12-50 micrograms kg-1), produced a dose-dependent excitation of afferent vagus nerve activity. These excitatory effects were antagonized by GR38032F (10 micrograms kg-1) and ketanserin (10 micrograms kg-1), respectively. 4. A 5-HT1 like receptor agonist, 5-carboxamidotryptamine (50 micrograms kg-1), and a putative 5-HT4 receptor agonist, 5-methoxytryptamine (100 micrograms kg-1), failed to produce excitatory effects on the afferent vagus nerve. 5. These results suggest that the 5-HT-induced excitatory response of the afferent vagus nerve might be mediated not only via 5-HT3 receptors but also via 5-HT2 receptors in anaesthetized rats. It is unlikely, however, that either 5-HT1-like or putative 5-HT4 receptors are involved in the excitatory response of the afferent vagus nerve to 5-HT.
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PMID:Pharmacological characterization of 5-hydroxytryptamine-induced excitation of afferent cervical vagus nerve in anaesthetized rats. 138 26

Ondansetron (GR 38032) has potent and highly selective antagonist properties at the 5-hydroxytryptamine (5-HT, serotonin) 5-HT3 receptor. The selectivity ratio for ondansetron on 5-HT3 receptors compared with actions on other neurotransmitter receptor types is greater than 1,000. The antiemetic properties of ondansetron have been determined in ferrets against the nausea and vomiting induced by cisplatin, cyclophosphamide, and whole-body radiation. Ondansetron (intravenous 0.01 to 0.1 mg/kg or subcutaneous 0.1 to 0.5 mg/kg) or metoclopramide (1.0 to 4.0 mg/kg) cause dose-dependent inhibitions of the vomiting induced by each of these procedures. Unlike ondansetron, the effects of metoclopramide are accompanied by moderate to marked behavioral depression. Since metoclopramide is 50 times more potent on dopamine D2 receptors than on 5-HT3 receptors, the behavioral depression is likely due to profound blockade of dopamine receptors. The 5-HT3 receptors have been shown to be present peripherally on vagal afferent fibers and are densely located in the vomiting center of the hindbrain. The current hypothesis is that there may be both a peripheral and a central site of action for ondansetron and other 5-HT3 antagonists. The lack of antagonist activity on dopamine and other non-5-HT3 receptors indicates that, unlike metoclopramide, ondansetron will not cause extrapyramidal or other dose-limiting side effects.
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PMID:Pharmacology and preclinical antiemetic properties of ondansetron. 138 45

Ondansetron, a potent and highly selective 5-HT3 receptor antagonist, prevents emesis following chemotherapy by antagonising the action of 5-hydroxytryptamine (5-HT) at 5-HT3 receptors on vagal afferent neurons that innervate the gastrointestinal tract and 5-HT3 receptors in the central vomiting system. Evidence suggests that chemotherapy induces the release of 5-HT from enterochromaffin cells in the small intestine. This stimulates vagal afferent nerves via 5-HT3 receptors. Information is then relayed, via the vagus nerve, to the central vomiting system. 5-HT3 receptors are also found in the hind-brain vomiting system including the area postrema (the site of the chemoreceptor trigger zone for emesis). Therefore, following chemotherapy, 5-HT activates 5-HT3 receptors at 2 sites to induce emesis. Clinical data showing that a single dose of ondansetron prevents acute emesis suggest that it is important to block the initiation of the emetic reflex. This may prevent the recruitment of central mechanisms involving 5-HT3 receptors.
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PMID:Mechanism of the anti-emetic activity of 5-HT3 receptor antagonists. 138 26

The effect of antagonists of serotonin (5-HT) receptor subtypes and alpha 2-adrenoceptors was investigated on audiogenic seizures and locomotor activity in DBA/2 mice. 5HT1c receptor antagonists (mianserin and cyproheptadine), 5-HT3 receptor antagonist (zacopride) and 5-HT4 receptor antagonist (ICS 205-930) increased the latency of audiogenic seizures and decreased the severity of convulsions in young (20-27 days old) DBA/2 mice. However, the effect of these antagonists varied in older (30-37 days old) mice. Ketanserin, 5-HT2 receptor antagonist, was devoid of any activity on audiogenic seizures. Yohimbine (0.5 mg/kg, i.p.), an alpha 2-adrenoceptor antagonist, increased the severity of audiogenic seizures, and the anti-convulsant effect of 5-HT receptor subtypes antagonists became more pronounced in the presence of yohimbine. 5-HT3 and 5-HT4 receptor antagonists produced hypolocomotor activity in young mice whereas 5-HT1c and 5-HT2 receptor antagonists were devoid of any effect on locomotor activity. Yohimbine did not induce any effect on locomotor activity but the mice exhibited more pronounced hypolocomotor activity following the administration of 5-HT3, 5-HT4 and 5HT1c receptor antagonists in the presence of yohimbine. However, the results varied with these agents in the older mice. These observations implicate a role of 5-HT1c, 5-HT3, 5-HT4 and alpha 2-adrenoceptors in audiogenic seizures in young DBA/2 mice, and 5-HT3 and 5-HT4 receptors in locomotor activity in these mice. Furthermore, these results also suggest an interaction between 5-HT receptors and alpha 2-adrenoceptors, and differential development patterns of various 5-HT receptor subtypes in the CNS.
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PMID:Effects of 5-HT receptor antagonists on seizure susceptibility and locomotor activity in DBA/2 mice. 139 77


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