Roles of the basal level of LH and FSH in the regulation of follicular development during pseudopregnancy in the rat.

摘要

Antiserum against LHRH (LHRH-AS) or charcoal-treated pig follicular fluid (PFF; a crude inhibin preparation) was given to rats on day 5 of pseudopregnancy. Plasma LH and inhibin decreased after treatment with LHRH-AS, but plasma FSH increased afterLHRH-AS injection. The number of follicles capable of ovulating in response to HCG in rats given LHRH-AS declined gradually, reached a nadir at 24 h after treatment, and then returned to control levels during the subsequent 24 h. On the other hand, plasma FSH levels in rats given 3 injections of 0.5 ml PFF at 6-h intervals, compared with those in control animals, remained significantly lower at nearly all time points during the first 24 h after the initial PFF injection, and thereafter the hormone levels temporarily increased, being significantly elevated above the control values at 30 and 42 h after the initial PFF injection. Only in the rats given intraperitoneal injections of 0.5 ml PFF did plasma LH concentrations remained significantly lower thanin controls at 9 h after the initial PFF injection, and the concentrations were significantly higher than in controls at 36 h after the initial treatment. The number of follicles capable of ovulating in response to HCG decreased in PFF-treated animals ina dose-dependent-manner. Follicular development in rats given an injection of 0.5 ml PFF were virtually or completely inhibited from 12 to 36 h after the initial injection of PFF. The results clearly indicate that the basal secretion of LH and FSH is essential for follicular development and maintenance during pseudopregnancy of the rat. They also suggest that inhibin is a primary factor in suppression of FSH secretion in the pseudopregnant rat.