The effect of pulsatile and continuous intravenous luteinizing hormone-releasing hormone administration on pituitary luteinizing hormone and follicle-stimulating hormone release in normal men

In 14 healthy, potentially fertile men, pituitary gonadotropin responses were studied under standardized conditions. Luteinizing hormone-releasing hormone (LH-RH) was given as a continuous infusion of 1μg/minute for 4hours or in a pulsatile fashion with 20μg as an intravenous bolus at intervals of 20minutes for 4hours. Blood was collected continuously by means of an integrated sampling technique. The mean serum luteinizing hormone (LH) concentration showed an oscillating pattern around a plateau level reached within 45minutes during continuous LH-RH administration. During pulsatile infusion, an identical pattern for the first 45minutes was observed with, thereafter, a continuous increase from 105minutes until the end of the infusion. The mean increase in the serum LH level during pulsatile administration was significantly higher (P=0.00001) than the mean increase seen during continuous infusion. The follicle-stimulating hormone concentration revealed a gradual progressive increase after both methods of stimulation, without a significant difference in the mean increase between the two types of administration. This study demonstrates the existence of a self-priming effect of LH after pulsatile LH-RH administration in the man like that in the woman.