title: Serotonin-mediated modulation of acetylcholine-induced intracellular calcium responses in chromaffin cells isolated from the rat adrenal medulla.
abstract: We examined serotonin (5-HT)-mediated modulation of acetylcholine (ACh)-induced intracellular Ca2+([Ca2+]i) responses in rat adrenal chromaffin cells using calcium imaging. 5-HT did not induce any [Ca2+]iresponse in clustered chromaffin cells. However, the magnitude of ACh-induced [Ca2+]iincreases in the same specimens was inhibited in the presence of 5-HT. ACh-induced [Ca2+]iincreases in chromaffin cells were also inhibited by the 5-HT1A receptor agonist, 8-hydroxy-2-(dipropylamino) tetralin hydrobromide, but were not changed by the 5-HT1B, 5-HT2, or 5-HT3 receptor agonists, CP93129, α-methyl-5-HT, or 1-(m-chlorophenyl) biguanide, respectively. RT-PCR analysis detected the expression of all 5-HT receptor subtype mRNAs, except for 5-HT5 receptors, in extracts of the adrenal medulla. Immunohistochemistry revealed that immunoreactivity for 5-HT1A receptor was located in the chromaffin cells immunoreactive for the biosynthetic enzyme for noradrenaline, dopamine β-hydroxylase. These results suggest that 5-HT inhibits ACh-induced excitability in adrenal chromaffin cells via the 5-HT1A receptor in order to reduce catecholamine release during preganglionic sympathetic stimuli.
authors.affiliation: Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan. Electronic address: ytakuya@iwate-med.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yokoyama
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan. Electronic address: yyoshio@iwate-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saino
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism; D019439:Chromaffin Cells / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*
chemical_list: D002395:Catecholamines; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D000109:Acetylcholine; D002118:Calcium
keywords: Adrenal medulla; Chromaffin cells; Intracellular calcium ion; Serotonin