title: Goldfish brain somatostatin-28 differentially affects dopamine- and pituitary adenylate cyclase-activating polypeptide-induced GH release and Ca(2+) and cAMP signals.
abstract: Dopamine (DA) and pituitary adenylate cyclase-activating polypeptide (PACAP) stimulate goldfish growth hormone (GH) release via cAMP- and Ca(2+)-dependent pathways while DA also utilizes NO. In this study, identified goldfish somatotropes responded to sequential applications of PACAP and the DA D1 agonist SKF38393 with increased intracellular Ca(2+) levels ([Ca(2+)](i)), indicating that PACAP and DA D1 receptors were present on the same cell. A native goldfish brain somatostatin (gbSS-28) reduced SKF38393-stimulated cAMP production and PACAP- and NO donor-elicited GH and [Ca(2+)](i) increases, but not PACAP-induced cAMP production nor the GH and [Ca(2+)](i) responses to forskolin, 8-bromo-cAMP and SKF38393. gbSS-28 might inhibit PACAP-induced GH release by interfering with PACAP's ability to increase [Ca(2+)](i) in a non-cAMP-dependent manner. However, DA D1 receptor activation bypassed gbSS-28 inhibitory effects on cAMP production and NO actions via unknown mechanisms to maintain a normal [Ca(2+)](i) response leading to unhampered GH release.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yu
authors.forename: John P
authors.initials: JP
authors.lastname: Chang
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D005260:Female; D006054:Goldfish / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D015290:Second Messenger Systems / Q000187:drug effects*; D053561:Somatostatin-28 / Q000494:pharmacology*
chemical_list: D018491:Dopamine Agonists; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D017447:Receptors, Dopamine D1; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D053561:Somatostatin-28; D013006:Growth Hormone; D000242:Cyclic AMP; D002118:Calcium; D004298:Dopamine