Molecular Pharmacology, Vol 18, 45-48, Copyright © 1980 by the American Society for Pharmacology and Experimental Therapeutics

Effects of Androgens on Isoproterenol-Sensitive Adenylate Cyclase System of the Rat Prostate

¹ Departments of Pharmacology and Neuropsychiatry, St. Marianna University School of Medicine, Kawasaki, Kanagawa, 213, Japan

Adrenergic stimulation of the cyclic AMP system of the prostate from intact, shamoperated, and castrated rats has been investigated. Castration markedly reduced isoproterenol activation of adenylate cyclase associated with a fall in -adrenergic receptor sites in the prostatic membrane. These results imply that a loss in the number of adrenergic receptors might be a major mechanism responsible for the decreased responsiveness of the prostatic adenylate cyclase to isoproterenol induced by castration. In addition to the decreased receptors, 5'-guanylyl-imidodiphosphate (Gpp(NH)p) was without effect on the cylcase activity and the receptor-ligand affinity in the prostate of castrated rats, suggesting some defects in GTP-regulating mechanisms on the receptor-adenylate cyclase complex. Supplementation of testosterone propionate to castrated rats restored the response to isoproterenol of the enzyme activity and the concentration of adrenergic receptors to levels at precastration. These findings suggest that endogenous androgens are involved in maintenance of -adrenergic receptors linked to the adenylate cyclase system of the prostatic membrane for the full expression of isoproterenol stimulation.