EFFECT OF THYROTROPIN RELEASING HORMONE (TRH) ON THE MENSTRUAL CYCLE IN WOMEN

Abstract

The effect of thyrotropin releasing hormone (TRH) on the menstrual cycle of eumenorrheic women was investigated. It was reported previously that TRH therapy in baboons blocked ovulation when administered early in the menstrual cycle and produced luteolysis when given during the luteal phase of the cycle. Whether these antifertility effects were associated with elevation in prolactin (PRL) secretion or produced by another mechanism was not apparent. It has been suggested that PRL probably decreases ovarian sensitivity to gonadotropins and thereby acts as an antifertility agent during the period of puerperal lactation. In the experiment described TRH was given to 6 women for 8 consecutive days beginning Days 8 and 9 of the menstrual cycle. Daily serum samples were obtained for radioimmunoassay for LH FSH and PRL secretory response. TRH was ineffective in interfering with ovulation and failed to show significant effects on cycle lengths. Moreover the length of the luteal phase was not affected by TRH as demonstrated by basal body temperature endometrial biopsy and pregnanediol excretion. These findings are in disagreement with the recent findings in baboons receiving TRH. The study also demosntrated that TRH administration induces a PRL secretory response which blocks neither the LH surge nor the ovarian responsiveness to endogenous gonadotropins in women who menstruate normally.