Serotonin contracts the isolated rat pylorus via a 5-HT2-like receptor
Eberle-Wang, K.; Braun, B.T.; Simansky, K.J.
American Journal of Physiology 266(1 Pt 2): R284-R291
1994
ISSN/ISBN: 0002-9513 PMID: 8304552 Document Number: 430426
Serotonin (5-HT) produced concentration-dependent contractions of the isolated rat pylorus in vitro. Serotonergic contractions were antagonized by the calcium L-channel blocker, diltiazem, but not by tetrodotoxin or atropine. Three drugs that block 5-HT-2 receptors, ketanserin, xylamidine, and methysergide, unsurmountably inhibited contractions to 5-HT. In contrast, antagonists of 5-HT-3, 5-HT-1A/1B, beta-adrenergic, or alpha-1-adrenergic receptors did not alter the response to 5-HT. Devazepide, an antagonist of cholecystokinin (CCK) type-A receptors, blocked contraction produced by CCK-8 but not by 5-HT. Conversely, the 5-HT-2 antagonists did not affect CCK-stimulated contraction. These results suggest that 5-HT contracts the pylorus by a 5-HT-2-like receptor on muscle and that this response occurs independently of CCKergic receptor mechanisms. Furthermore, the parallel between the overall pharmacological profile for serotonergic contraction of the pylorus and that observed previously for the anorectic action of peripheral 5-HT makes the pylorus a logical candidate for peripheral serotonergic control of feeding.