Effect of androgens on penile tissue

There are two ways to establish that androgens play a major role in the function and integrity of erectile tissue: (1) discussing a number of physiology and molecular biology studies that have been published from experiments in animals and (2) reporting the effect of androgens on penile tissue, or in many cases the lack of androgen, in man. A variety of animal models, and also human studies, have shown the existence of androgen receptors in the corpora cavernosa. The penile erectile response in the laboratory rat is androgen dependent, and the active androgen appears to be dihydrotestosterone. There are several articles that describe the androgenic regulation of nitric oxide synthase (the enzyme responsible for production of nitric oxide), the primary agent controlling the erectile cycle. There have been few reports showing a direct end organ dependency of androgen for erectile function in the human corpora cavernosa, although there is plenty of evidence demonstrating that low or absent androgens affect a man's ability to have an erection in a sexual situation. Thus, in man androgen dependency for cavernous tissue smooth muscle function is still debatable. Extrapolating animal dependency of androgens for molecular activity in the penile tissue remains the most reasonable suggestion for androgen dependency of the cavernous tissue in man.