Pituitary and Gonadal Desensitization after Continuous Luteinizing Hormone-Releasing Hormone Infusion in Normal Females*

Abstract

Three normal females were studied during the early follicular phase of the menstrual cycle employing a continuous infusion of LHRH (1.4 micrograms/min) for 72 h. Blood samples were taken every 4 h. LH concentrations climbed from 9.3 mIU/ml basally to peak values of 120 mIU/ml at 12 h, then fell to a plateau between 23-31 mIU/ml from 36-72 h. FSH levels rose from 5.4 to 36 mIU/ml at 4 h of infusion and then returned to baseline. 17 beta-Estradiol increased from 48 to 184 pg/ml at 32 h, but subsequently fell toward basal concentrations. 17-Hydroxyprogesterone increased from 0.5 to 1.23 ng/ml at 12 h and remained elevated for the remainder of the infusion period. Serum progesterone levels remained constant. Three females with premature ovarian failure were studied, and the pattern of gonadotropin release was similar to that of normal subjects. Studies demonstrate that continuous LHRH infusion in normal females causes pituitary and gonadal desensitization. The desensitization of the pituitary is independent of gonadal activity.