Pituitary and Testicular Response to LH-RH and to a Long-Acting Analogue (D-Leu-6-LH-RH-Ethylamide)

Abstract

The LH, FSH and testosterone response to 50 microgram i.v. LH-RH and to 2.5, 5.0, 10.0, and 20.0 microgram i.m. D-Leu-6-LH-RH-ethylamide was studied in 6 subjects with normogonadotrophic, idiopathic oligozoospermia. All injections were given between 8:00 and 9:00 a.m. at weekly intervals. Blood samples were collected before and 30 and 45 minutes after injection of LH-RH, and before and 2, 4, 6, 12, and 24 hours after D-Leu-6-LH-RH-ethylamide injections. Serum levels of LH, FSH, and testosterone were measured by triplicate by R.I.A. LH and FSH responses to LH-RH showed peak values at 30 minutes, whereas following injections of D-Leu-6-LH-RH-ethylamide, maximal values were recorded between 4 and 6 hours and were higher than those obtained with LH-RH. A significant rise of serum testosterone levels was observed after all stimuli, with peak values 45 minutes after LH-RH and 4 to 6 hours after D-Leu-6-Lh-RH-ethylamide injections. The testosterone levels obtained following LH-RH and different doses of the analogue did not differ significantly from one another. The same sequence of maximal LH and FSH values was obtained after injections of LH-RH and of D-Leu-6-LH-RH-ethylamide, particularly at doses of 10.0 and 20.0 microgram. This suggests that the gonadotrophin response to these agents would be a true reflection of the individual mode of pituitary response.