Inhibitory Effects of Porcine Follicular Fluid on Monkey Serum FSH Levels and Follicular Maturation1

To examine the role of FSH during follicular maturation in monkeys, serum FSH was suppressed during cycles on Days 1–4 i.p. by administration of charcoal-treated porcine follicular fluid (PFFl, crude inhibin-F). Following PFFl treatment, the putative dominant follicle was examined on Days 10–14. Granulosa cells were recovered from this follicle and cultured. Treatment of four monkeys with PFFl led to decreased size of the dominant follicle and a decrease in the number of granulosa cells recovered from the follicle. Serum FSH, but not LH, levels were decreased 50–80% in three of four monkeys. Pig serum (control) had no discernible effects. The actions of charcoal-treated PFFl were examined further in long-term castrate female cynomolgus and rhesus monkeys. With a single injection of 0.5, 1.0, 5, 10, 15, or 100 ml of PFF PFFl administration at time 0, there was a dose-dependent decrease in FSH, with no significant alteration in serum LH. With the lowest dose (5.0 ml), there was a 25% decrease (P<0.05) in serum FSH after 42 h. Both 30 and 100 ml doses produced a near maximal decrease (70–80%) in serum FSH. This observation may indicate that there are two "pools" of FSH, one of which is not suppressible by PFFl, or that there is a single pool which is not completely suppressible by this experimental approach. Additional experiments were performed in monkeys to examine the effect of PFFl administered during the spontaneous midcycle and exogenous estrogen-induced FSH/LH surges. PFFl was injected in two to four daily doses of 4 ml each during the anticipated time of the midcycle gonadotropin surges. These 4-day PFFl treatments led to postponement of the LH/FSH surges in two monkeys and the abolishment of the anticipated LH/FSH surges in two additional monkeys. These four PFFl-treated monkeys failed to ovulate in the treated cycle, but did ovulate during the next menstrual cycle. Administration of porcine serum at midcycle did not alter the midcycle LH/FSH surge. Administration of a daily 10 ml dose of PFFl over a 4 day period inhibited the estrogen-induced (estradiol benzoate) rise of LH and FSH in a total of five intact adult female cynomolgus and rhesus monkeys during the early follicular phase. In a final experiment, s.c. administration of 2 ml PFFl, but not pig serum, to both male and female infant (12–17 month) rhesus monkeys led to a selective decline in serum FSH.