In vitro and in vivo effects of ghrelin on luteinizing hormone and growth hormone release in goldfish.
We studied the in vitro and in vivo effects of octanoylated goldfish ghrelin peptides (gGRL-19 and gGRL-12) on luteinizing hormone (LH) and growth hormone (GH) release in goldfish. gGRL-19 and gGRL-12 at picomolar doses stimulated LH and GH release from dispersed goldfish pituitary cells in perifusion and static incubation. Incubation of pituitary cells for 2 h with 10 nM gGRL-12 and 1 or 10 nM gGRL-19 increased LH-beta mRNA expression, whereas only 10 nM gGRL-19 increased GH mRNA expression. Somatostatin-14 abolished the stimulatory effects of ghrelin on GH release from dispersed pituitary cells in perifusion and static culture. The GH secretagogue receptor antagonist d-Lys(3)-GHRP-6 inhibited the ghrelin-induced LH release, whereas no effects were found on stimulation of GH release by ghrelin. Intracerebroventricular injection of 1 ng/g body wt of gGRL-19 or intraperitoneal injection of 100 ng/g body wt of gGRL-19 increased serum LH levels at 60 min after injection, whereas significant increases in GH levels were found at 15 and 30 min after these treatments. Our results indicate that, in addition to its potent stimulatory actions on GH release, goldfish ghrelin peptides have the novel function of stimulating LH release in goldfish.
Department of Biological Sciences, University of Alberta, Edmonton, Canada T6G 2E9.
Suraj
S
Unniappan
Richard E
RE
Peter
D000818:Animals; D015153:Blotting, Western; D046508:Culture Techniques; D054439:Ghrelin; D006054:Goldfish / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D007986:Luteinizing Hormone / Q000378:metabolism*; D036361:Peptide Hormones / Q000494:pharmacology*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D054440:Receptors, Ghrelin; D013004:Somatostatin / Q000494:pharmacology
D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D013004:Somatostatin; D007986:Luteinizing Hormone; D013006:Growth Hormone