Inhibition of cholera toxin-induced intestinal secretion by the 5-HT3 receptor antagonist ICS 205-930.
The secretory effect of cholera toxin on the gut has been ascribed to the activation of submucosal 5-hydroxytryptamine receptors by 5-hydroxytryptamine released from the enterochromaffin cells. The hypothesis that neuronally located 5-HT3 receptors are involved in cholera toxin-induced diarrhoea has now been tested. Intestinal secretion was stimulated in mice by oral administration of pure cholera toxin and the effects of ICS 205-930, a potent and selective antagonist at 5-HT3 receptors, and of ketanserin, a compound that blocks 5-HT2 receptors, were investigated. Oral administration of cholera toxin resulted in a significant accumulation of fluid in the intestine. Pretreatment of the animals with ICS 205-930 partly prevented this effect and a maximal reduction of about 50% was achieved with doses of 0.3 mg/kg i.p. and higher. Ketanserin had only minimal effects up to a high dose of 1 mg/kg i.p. when a 20% reduction of fluid accumulation was seen. The data support the view that activation of 5-HT3 receptors plays a major role in the secretory effect of cholera toxin in the gut.
Preclinical Research, Sandoz Ltd., Basel, Switzerland.
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D000818:Animals; D002772:Cholera Toxin / Q000037:antagonists & inhibitors*; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051379:Mice; D012702:Serotonin Antagonists / Q000494:pharmacology*; D000077526:Tropisetron
D007211:Indoles; D012702:Serotonin Antagonists; D000077526:Tropisetron; D002772:Cholera Toxin; D007650:Ketanserin