Luteinizing Hormone-Releasing Hormone and Thyrotropin-Releasing Hormone in the Hypothalamus of Women: Effects of Age and Reproductive Status*

In the study of the effects of age and reproductive status on LHRH and TRH content in the hypothalamus of women, we found that the amount of LHRH (58 +/- 5.5 ng; mean +/- SE) in the hypothalamus of young women (16-29 yr) was significantly greater (P less than 0.001) than that (28 +/- 3.0 ng) in postmenopausal women (50-78 yr). The hypothalamic content of LHRH (18 +/- 2.4 ng) of bilaterally ovariectomized women (39-47 yr) was significantly less (P less than 0.001) than that (60 +/- 12.6 ng) in younger ovulatory women (30-39 yr) or that (56 +/- 13.5 ng) in ovulatory women of comparable age (40-49 yr). In contrast, the hypothalamic content of TRH (121.4 +/- 32.8 ng) in postmenopausal women were similar to that (122.3 +/- 12.5 ng) in young women. Although aging in women is associated with a significant reduction in the amount of LHRH in the hypothalamus, such a reduction appears to be a consequence of ovarian failure and not of aging per se.