Pituitary response to exogenous LHRH in superovulated women

The response of the pituitary to exogenous LHRH was investigated in 9 normally ovulating women during the late follicular phase of a spontaneous (control) cycle, a cycle during treatment with clomiphene and a cycle during treatment with 'pure' FSH. During clomiphene treatment, basal FSH concentrations increased significantly up to Day 6 of the cycle and then decreased progressively while basal LH values showed a continuous rise. During treatment with FSH, basal LH concentrations decreased significantly. The response of both FSH and LH to LHRH showed a significant and quantitatively similar decrease during clomiphene or FSH administration as compared to the spontaneous cycles. It is suggested that basal secretion of FSH and LH is regulated by two separate mechanisms, and that an ovarian inhibitory factor(s) attenuates the response of both FSH and LH to exogenous LHRH and possibly the endogenous LH surge in superovulated cycles.