An effect of isoproterenol on rates of synthesis and secretion of testosterone.

EIK-NES, K. B. An effect of ~,roprotereno~ n rafes of synthesis and secretion of testosterone. Am. J. Physiol. 2 17(6) : 1764-I 770. 1969.When epinephrine, norepinephrine, ethylnorepinephrine, or isoproterenol was infused al a constant rate via the spermatic artery of the dog, the level of testosterone increased in spermatic venous blood. Of the catecholamines tried, isoproterenol was the strongest stimulator of testosterone secretion, and in infusion experiments of 15 min duration the effect of isoproterenol on testosterone secretion was similar to that following gonadotrophin infusion. Testes infused with isoproterenol via the spermatic artery had higher tissue levels of testosterone than control testes; thus, isoproterenol enhances synthesis de novo of testosterone when infused via the spermatic artery. Since testes infused with a preceptor inhibitor via the spermatic artery secreted less testosterone than control testes when stimulated with isoproterenol, it is suggested that the integrity of testicular p-receptors may be of importance for the secretion of testosterone in vivo. Currently it is not understood if isoproterenol and the gonadotrophins promote secretion of testosterone by the same mechanism.