Authors: Daniel P Poole Bo Xu Shir Lin Koh Billie Hunne Ian M Coupar Helen R Irving Katsuhiro Shinjo John B Furness
Publish Date: 2006/04/21
Volume: 325, Issue: 3, Pages: 413-422
Abstract
5Hydroxytryptamine 5HT is an endogenous stimulant of intestinal propulsive reflexes It exerts its effects partly through 5HT4 receptors 5HT4 receptor agonists that are stimulants of intestinal transit are in clinical use Both pharmacological and recent immunohistochemical studies indicate that 5HT4 receptors are present on enteric neurons but the specific neurons that express the receptors have not been determined In the present work we describe the characterization of an anti5HT4 receptor antiserum that reveals immunoreactivity for enteric neurons and other cell types in the gastrointestinal tract With this antiserum 5HT4 receptor immunoreactivity has been found in the muscularis mucosae of the rat oesophagus a standard assay tissue for 5HT4 receptors It is also present in the muscularis mucosae of the guineapig and mouse oesophagus In guineapig small intestine and rat and mouse colon 5HT4 receptor immunoreactivity occurs in subpopulations of enteric neurons including prominent large neurons Doublestaining has shown that these large neurons in the guineapig small intestine are also immunoreactive for two markers of intrinsic primary afferent neurons cytoplasmic NeuN and calbindin Some muscle motor neurons in the myenteric ganglia are immunoreactive for this receptor whereas it is rarely expressed by secretomotor neurons Immunoreactivity also occurs in the interstitial cells of Cajal but is faint in the external muscle Expression of the protein and mRNA has been confirmed in extracts containing enteric neurons The observations suggest that one site of action of 5HT4 receptor agonists is the intrinsic primary afferent neurons
Keywords: