The release of serotonin from rat duodenal enterochromaffin cells by adrenoceptor agonists studied in vitro.
The serotonin (5-HT) content of enterochromaffin cells (EC) was studied by a cytofluorimetric method in biopsies from rat duodenal mucosa after in vitro incubation with different adrenoceptor agonists and antagonists and acetylcholine (ACh). Noradrenaline (NA), Adrenaline (A) and Isoprenaline (IP) caused a decrease of 5-HT in EC down to 40--60% and for NA and A this effect was concentration-dependent. The effect was antagonized by d,1-propranolol but not by d-propranolol, metoprolol, phentolamine or phenoxybenzamine indicating that the 5-HT release from EC is probably mediated via a true beta-adrenoceptor mechanism possibly of the beta2 type. ACh also decreased the 5-HT content of EC but was much less potent than the adrenergic substances. Dopamine (DA) had no effect.
D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D000818:Animals; D002838:Chromaffin System; D004298:Dopamine / Q000494:pharmacology; D004386:Duodenum / Q000378:metabolism; D004759:Enterochromaffin Cells; D004837:Epinephrine / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D010643:Phenoxybenzamine; D012701:Serotonin; D011433:Propranolol; D008790:Metoprolol; D007545:Isoproterenol; D000109:Acetylcholine; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine