A possible vagal adrenergic release of serotonin from enterochromaffin cells in the cat.
The intracellular concentrations of serotonin (5-HT) in enterochromaffin cells (EC) in the cat small intestine have been studied by a cytofluorimetric method before and after long-lasting efferent vagal nerve stimulation in the neck. Such stimulation induces a decrease of 5-HT in EC of the gut as observed previously. Pretreatment with atropine could not block this decrease, suggesting a noncholinergic mechanism. Pretreatment with a beta-blocking agent, propranolol, or bilateral removal of the superior cervical ganglia could, however, block this 5-HT decrease. Pretreatment with an alpha-blocking agent, phenoxybenzamine, caused an increase in the 5-HT content of EC both with and without nerve stimulation; the reason for this is obscure. The results indicate, that vagal nerve stimulation induces a neurogenic 5-HT release from EC in the gut, and that adrenergic fibres, originating in the superior cervical ganglia, mediate this release probably via a beta-receptor mechanism. Whether or not an alpha-receptor mechanism is also involved cannot be judged at present.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D002838:Chromaffin System / Q000502:physiology*; D003714:Denervation; D004558:Electric Stimulation; D004759:Enterochromaffin Cells / Q000502:physiology*; D005260:Female; D005470:Fluorometry; D006651:Histocytochemistry; D007421:Intestine, Small / Q000294:innervation / Q000378:metabolism; D008297:Male; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects; D011950:Receptors, Cholinergic / Q000187:drug effects; D012636:Secretory Rate / Q000187:drug effects; D012701:Serotonin / Q000378:metabolism*; D014630:Vagus Nerve / Q000502:physiology*
D011941:Receptors, Adrenergic; D011950:Receptors, Cholinergic; D010643:Phenoxybenzamine; D012701:Serotonin; D001285:Atropine; D011433:Propranolol