Plasma and follicular steroid levels of laying hens after the administration of gonadotropins.

Abstract

Chicken or ovine gonadotropins were injected into laying hens at 12 h after the C1 oviposition (approximately 14 h before the C1 ovulation). Plasma and the walls of the 3 largest follicles were taken from the hens within the period from 15-90 mm after hormone injection to be assayed for progesterone (P) and estrogen (E) by RIA. P concentrations in plasma and in the 3 largest follicles, particularly the largest one, rose sharply during the first 30 mm after the injection of chicken anterior pituitary (CP) or ovine LH (oLH) and reached maximum at 30 mm. Plasma and follicular P were sustained ass high level for 90 mm after the CP injection, while the P levels in hens given 0LH decreased from 455090 mm after injection of oLH. CP was effective in causing significant elevation of E in plasma and the 2 smaller follicles. but not in the largest one. at 30 and 45 mm after the injection, while no such increase was induced by 0LU, excepting in the third follicle, but at only I time point. The injection of ovine FSH (oFSH). at the highest dose level (400 �tg) used. resulted in significant increases of follicular P and plasma F. Synergistic effect between oFSH and oLH was found on P synthesis and release, but not on F. The values of plasma and follicular P elevated by CP and 0LH werecomparable to those of the preovulatory peak in the normal cycle.