Time Course of Serum FSH Suppression in Ovariectomized Rats Injected with Porcine Follicular Fluid (Folliculostatin): Effect of Estradiol Treatment

Abstract

A semipurified fraction of porcine follicular fluid (≥10,000 daltons), injected i.p., lowered serum FSH in rats tested 7 days after ovariectomy. The decrease was dose-dependent and showed a latency of more than 3 h; suppression lasted between 5–14 h and was lost by 24 h. Serum LH was not suppressed by the fluid. Superimposition of estradiol from Silastic implants suppressed LH to basal levels found during the estrous cycle, but did not lower FSH to basal levels in porcine serum injected controls. Follicular fluid further reduced FSH in estradiol treated animals to the low levels seen on nonproestrous days of the estrous cycle.