New insights into androgen treatment of erectile dysfunction

Erectile response in mammals is centrally and peripherally regulated by androgens. Severe hypogonadism in men usually results in loss of libido and potency which can be restored by androgen administration. The original insights into the mechanisms of action of androgens on sexual function indicated that androgens particularly exert effects on libido and that sleep-related erections were androgen-sensitive but erections in response to erotic stimuli were relatively androgen-independent. There are a number of recent developments which shed new light on testosterone treatment of erectile dysfunction in aging men. There is growing insight that testosterone has profound effects on tissues of the penis involved in the mechanism of erection and that testosterone deficiency impairs the anatomical and physiological/biochemical substrate of erectile capacity, reversible upon androgen treatment. Several studies have indicated that the administration of PDE-5-inhibitors is not always sufficient to restore erectile potency in men and that administration of testosterone improves the therapeutical response to PDE-5-inhibitors considerably. There is increasing insight not to view erectile dysfunction (ED) as a single entity but as part of the aging process. Circulating levels of testosterone are closely related to manifestations of other etiological factors in ED, such as atherosclerotic disease and diabetes mellitus. The latter are correlated with lower-than-normal testosterone levels