Effects of gonadotropin-releasing hormone on growth hormone secretion and gene expression in common carp pituitary.
Using radioimmuno- and ribonuclease protection assays, we examined the effects of gonadotropin-releasing hormone and its analogs on the growth hormone mRNA level and growth hormone secretion in common carp (Cyprinus carpio) pituitary fragments with static incubation. After a 24 h treatment, sGnRH ([Trp(7),Leu(8)]-LHRH) and sGnRH-A ([D-Arg(6),Pro(9)]-LHRH) (0.1 nM-1 microM) elevated the GH mRNA level and stimulated the GH secretion in a dose-dependent manner, with a higher potency for sGnRH-A. In a time-course experiment, the function of sGnRH and sGnRH-A (10 nM) on GH secretion was observed after 6 h incubation, while no action on the GH mRNA level were noted until 12 h after treatment. Comparing mammalian GnRH, avian GnRH and piscine GnRH, sGnRH and sGnRH-A showed the highest potency in increasing GH mRNA level and GH-release, followed by cGnRH-II ([His(5),Tyr(8)]-LHRH), and finally LHRH and LHRH-A([D-Trp(6), Pro(9)]-LHRH). These findings, taken together, suggest that GnRH not only can influence GH release, but also play a role in the regulation of GH synthesis.
Li
Wen-Sheng
WS
School of Life Sciences, Zhongshan University, Guangzhou 510275, PR China.
Lin
Hao-Ran
HR
Wong
Anderson O L
AO
D000818:Animals; D001717:Birds; D002347:Carps / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008322:Mammals; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D013006:Growth Hormone