LH Response to LH-Releasing Hormone and Its Relationship to 17β-Estradiol in Ovariectomized Rats and Anovulatory Women1

ABSTRACT 17β-Estradiol (E2) was given to ovariectomized rats in doses of 0.0, 0.4, 4.0, 40.0 and 400.0 μg/rat 24 hr prior to treatment with 500 ng synthetic LHRH iv under urethane anesthesia. LH was measured in the serum at the time of LHRH administration and 20 min later. There was no change in the baseline LH concentration as a result of the E2 treatment; however, the changes in the LH concentration at 20 min were 344 and 1,196% above the initial levels respectively in rats which received 0.0 and 400 μg E2. A positive linear regression between the log of the pretreatment dose of E2 and the change in serum LH concentration was found. There was no significant correlation between serum E2 concentration in 15 women with anovulatory infertility and the initial, peak or per cent change in either serum LH or FSH concentration following 100 μg LHRH sc