title: Serotonin secretion from rat Leydig cells.
abstract: In rat Leydig cells, serotonin (5HT) binds to 5HT2 receptors and stimulates the secretion of CRF which in turn acts as an inhibitor of gonadotropin-induced cAMP formation and androgen production. In the present study we defined the regulation of 5HT secretion in cultured Leydig cells. Adult Leydig cells secreted considerable quantities of 5HT (100-150 pg/10(6) cells per 10 min). The release of 5HT was acutely stimulated by hCG (ED50, 1.1 pM) with maximal stimulation at 10 pM hCG (160%). Forskolin also increased (+220%) 5HT release from cultures (ED50, 50 nM) while TPA was much less effective (+20%), indicating a major role for cAMP in gonadotropin-induced 5HT release. This was confirmed by the finding that 8-Br cAMP (1 mM) was an effective stimulus of 5HT release (+360%). Similar increases of 5HT release by hCG were observed in the absence of extracellular Ca2+. However, ionomycin was a potent stimulus of 5HT release, indicating that elevation of cytoplasmic [Ca2+] could also induce amine secretion. The 5HT content of Leydig cells ranged from 300 to 350 pg/10(6) cells, and decreased during stimulation of 5HT release. Also, immunohistochemical studies revealed specific staining of 5 HT in interstitial cells of the adult rat testis. These studies demonstrated that rat Leydig cells contain and secrete 5HT, and that 5HT release is stimulated by gonadotropin acting primarily through a cAMP-mediated mechanism.
authors.affiliation: Section on Molecular Endocrinology, National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD 20892.
authors.forename: J C
authors.initials: JC
authors.lastname: Tinajero
authors.forename: A
authors.initials: A
authors.lastname: Fabbri
authors.forename: D R
authors.initials: DR
authors.lastname: Ciocca
authors.forename: M L
authors.initials: ML
authors.lastname: Dufau
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015759:Ionomycin / Q000494:pharmacology; D007985:Leydig Cells / Q000378:metabolism*; D008297:Male; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D006063:Chorionic Gonadotropin; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D012701:Serotonin; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium