Differential involvement of nitric oxide signaling in dopamine and PACAP stimulation of growth hormone release in goldfish.
Previous studies in goldfish pituitary cells have shown that nitric oxide synthase (NOS)/nitric oxide (NO) signaling is involved in mediating the growth hormone (GH) release response to gonadotropin-releasing hormones. In this study, the involvement of this signaling pathway in mediating the action of two cAMP-mobilizing neuroendocrine stimulators of GH release, pituitary adenylate cyclase-activating polypeptide (PACAP) and dopamine (DA), was investigated in cell column perifusion experiments with primary cultures of dispersed pituitary cells. GH responses to PACAP were unaffected by three NOS inhibitors, aminoguanidine hemisulfate, 1400W and 7-nitroindazole (7-Ni). PACAP-stimulated GH release was also not reduced by two NO scavengers, rutin hydrate and PTIO, but NO-donor sodium nitroprusside (SNP)-elicited GH release was additive to the GH response to PACAP. In contrast, DA-induced GH secretion was reduced by 7-Ni, rutin hydrate and PTIO while not being additive to the GH response induced by SNP. These results indicate that although both PACAP and DA stimulation of acute GH release involve activation of adenylate cyclase/cAMP, DA- but not PACAP-signaling also utilizes the NOS/NO second messenger system.
Mitchell
Gabriel
G
Department of Biological Sciences, University of Alberta, CW 405, Biological Sciences Building, Edmonton, Alta., Canada T6G 2E9.
Sawisky
Grant R
GR
Grey
Caleb L
CL
Wong
Calvin J
CJ
Uretsky
Aubrey D
AD
Chang
John P
JP
D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D029941:Fish Proteins / Q000378:metabolism; D006054:Goldfish / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D018709:Statistics, Nonparametric
D004791:Enzyme Inhibitors; D029941:Fish Proteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D009569:Nitric Oxide; D013006:Growth Hormone; D019001:Nitric Oxide Synthase; D004298:Dopamine