Influence of testosterone substitution on sperm suppression by LHRH agonists.

To investigate the effect of LHRH (GnRH) agonists on sperm suppression, we studied the effect of a depot preparation of D-Trp6 LHRH in 10 normal men for 30 weeks. In addition, to determine the role of androgenic substitution on sperm suppression, the volunteers were divided into two groups: group 1 (n = 5) received a low dose T substitution (125 mg of T enanthate every month), while group 2 (n = 5) received a normal T substitution (120 mg of T undecanoate every day). Four men became azoospermic in group 1 and none in group 2. Moreover, administration of additional T injections in 1 volunteer of group 1 resulted in the reappearance of spermatozoa in the ejaculate. Return to the low dose therapy produced azoospermia. These results suggest that testosterone supplementation supports spermatogenesis.