THE TSH, FSH AND PROLACTIN RESPONSES TO CONTINUOUS INFUSIONS OF TRH AND THE EFFECTS OF OESTROGEN ADMINISTRATION IN NORMAL MALES

Abstract

SUMMARY Four normal males received a constant infusion of 0.9% NaCl for 1 hr followed immediately by 500 μg of TRH infused over the same period. A rise in serum TSH was observed in all subjects while in three there was also a significant FSH response. The prolactin response, unlike that of TSH, was markedly pulsatile indicating that different mechanisms exist for the release of these two hormones from the pituitary after TRH. Circulating levels of LH were unaffected. Ethinyl oestradiol, 30 μg daily for 3 days, was administered to two of the subjects and the infusions were repeated. Both basal FSH and LH levels were depressed, as was the FSH response to the infusion of TRH. By contrast, however, the TSH response to thyrotrophin releasing hormone was enhanced after oestrogen. In one subject the basal prolactin levels were significantly higher while in both there was an augmented prolactin response to TRH, the pulsatile pattern of release being maintained.