Pituitary gonadotropin responses to different modes and doses of intravenous luteinizing hormone-releasing hormone administration in normal men

In 22 potentially fertile men, pituitary gonadotropin secretion was investigated by intravenous luteinizing hormone-releasing hormone (LH-RH) administration. LH-RH was administered continuously (1 μg/minute) and in a pulsatile fashion (20 μg at 20-minute intervals, 20 μg at 60-minute intervals, and 60 μg at 60-minute intervals), for 3 hours, under standarized conditions. Blood was collected continuously by means of an integrated sampling technique. The mean serum luteinizing hormone (LH) concentration after any type of pulsatile administration rose significantly more than after continuous LH-RH administration. The mean increase in LH after pulsatile LH-RH administration with a 60-μg dose and 60-minute intervals was significantly greater than after pulsatile administration with a 20-μg dose and 20- or 60-minute intervals. No differences were observed in follicle-stimulating hormone responses after any type of LH-RH administration. These data confirm the existence of a self-priming effect for LH in the men; and maximum pituitary stimulation, within the dosage range tested, is reached after pulsatile LH-RH stimulation with an interval of 60 minutes.