[Gonadotropin secretion after stimulation with a highly effective analog of the gonadotropin-releasing-hormone (GnRH) in normal adult human males (author's transl)].

Potent long acting anologs of GnRH are of great interest especially in view of treatment of hypothalamic hypogonadotropic hypogonadism and of cryptorchidism. To find necessary parenteral doses of such a substance immunoreactive serum LH and FSH were measured in 4 normal adult human males after s.c. injection of various doses of D-Leu6-des-Gly10-GnRH-EA. 5 microgram of the GnRH anlog were necessary to obtain increased serum gonadotropins over a period of at least 8 h. Comparable maximal levels were seen after i.v. bolus injection of 25 microgram natural GnRH a dose as used in diagnostic routine tests in 3 probands. Comparing the areas under the curves of LH secretion an over 15 times greater effectiveness of the analog was calculated.