Cyclic changes in serum follicle-stimulating hormone, luteinizing hormone and inhibin during the guinea pig estrous cycle.

摘要

Sexually mature guinea pigs that had showed at least 2 consecutive normal 15-17 day cycles were studied. The day of maximal vaginal cornification, the day of ovulation, was designated as day 0. Blood samples were taken every other day at 09.00 h throughout one oestrous cycle. Serum was analysed for FSH, LH and inhibin by radioimmunoassay. Cyclic changes in peripheral FSH, LH, and inhibin concentrations were observed. Serum inhibin rose to a peak on day 7 of the oestrous cycle. Inhibin increased again, although not significantly, on day 13. Thus, this study confirms the biphasic phenomenon of ovarian follicle development in guinea pigs. Since serum FSH concentrations declined as serum inhibin concentrations reached a peak, it is also suggested thatinhibin regulates FSH secretion in this species.