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

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Abstract
Three normal females were studied during the early follicular phase of the menstrual cycle employing a continuous infusion of LHRH [luteinizing hormone releasing hormone, luliberin] (1.4 .mu.g/min) for 72 h. Blood samples were taken every 4 h. Lutropin concentrations climbed from 9.3 mIU/ml basally to peak values of 129 mIU/ml at 12 h, then fell to a plateau between 23-31 mIU/ml from 36-72 h. Follitropin 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. Continuous LHRH infusion in normal females apparently causes pituitary and gonadal desensitization. The desensitization of the pituitary is independent of gonadal activity.