Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2005
Publication Date: 7/1/2005
Citation: Proudman, J.A., Scanes, C., Johannsen, S., Berghman, L., Camp, M.J., Yu, W., Mccann, S. 2005. Comparison of the ability of the three gonadotropin releasing hormones (gnrh) to stimulate release of follicle stimulating hormone (fsh) and luteinizing hormone (lh) in chickens [abstract]. Poultry Science. 84(Suppl. 1):57. Interpretive Summary:
Technical Abstract: It is well established that GnRH can stimulate the release of LH and FSH in mammals. Two decapeptide releasing hormones for LH have been found in the chicken hypothalamus, chicken (c) GnRH I and cGnRH II. There is controversy as to whether either peptide can stimulate release of FSH in birds. The present studies compared the ability of cGnRH I and II to stimulate the release of FSH and LH in intact chickens. Lamprey (l) GnRH III may be a specific releasing factor for FSH, as it selectively stimulates FSH release in rodents and cattle, and has been detected in the hypothalamus of the rodent, the chicken, and the sparrow. Therefore, the ability of lGnRH III to stimulate LH and FSH release in chickens was also examined. In our first experiment, the effects of cGnRH I and II on FSH and LH release were studied using 17-wk White Leghorn pullets. Injection of cGnRH II at 1 and 10 'g/kg b.w. significantly increased LH secretion more than the same doses of cGnRH I. Neither peptide caused a significant change in plasma FSH levels. In our second study, we administered cGnRH I, cGnRH II or lGnRH III to mature roosters maintained on a short photoperiod. Again, cGnRH II was more potent than cGnRH I in stimulating LH release, while lGnRH III had no effect on LH. FSH secretion was significantly stimulated by the highest dose of cGnRH II, but neither cGnRH I nor lGnRH III elicited any significant FSH response. We conclude that none of the GnRH peptides studied provided a potent stimulus to FSH secretion, although a high dose of cGnRH II modestly enhanced FSH levels in adult male broiler breeders. There was no significant in vivo release of either LH or FSH in response to lGnRH III challenge in these birds. This result is not consistent with the view that lGnRH III is the FSH releasing hormone across multiple classes of vertebrates.