Adenyl cyclase activity was assayed in homogenates and washed particulate preparations of dog and rat testis. The formation of adenosine 3′,5′-monophosphate (cyclic AMP) from ATP by homogenates of dog testis was consistently increased 55-95% by addition of either interstitial cell stimulating hormone (ICSH) or follicle stimulating hormone (FSH), and NaF produced about a 155% increase. Relatively high concentrations of adrenocorticotropic hormone and l-epinephrine also enhanced adenyl cyclase activity (about 20%). Glucagon was without effect. The effect of l- epinephrine was also observed in the presence of maximal stimulation by either interstitial cell stimulating hormone or follicle stimulating hormone and could be prevented with beta-adrenergic blocking agents. The maximal effects of interstitial cell stimulating hormone and follicle stimulating hormone were, however, not aditive and were unaltered by adrenergic blocking agents. These observations provide evidence in support of the hypothesis that the physiologic and biochemical effects of interstitial cell stimulating hormone and follicle stimulating hormone in testis and probably in ovary are mediated through adenosine 3′,5′-monophosphate. © 1969.
