[Hormonal control of sexual behavior in males and endocrinologic causes of sexual dysfunction]

The role of androgens in the male sex differentiation, in the genesis and preservation of the erectile function is summarized. In sex differentiation, testosterone acts on genitalia and central nervous system (CNS). In CNS sexual steroids exert a morphogenetic action during neuronal development. At the pubertal age, the increase of testosterone leads to the development of sex characteristics, the onset of libido and the beginning of the nocturnal spontaneous erectile function. Spontaneous erections are androgen-dependent, and they are impaired in androgen deficiency. Normal androgen levels lead to make voluntary erections. However, in the human species, cortical influences may greatly affect what could be possible to occur in relation to the hormonal situation. Endocrine causes of sexual dysfunction are responsible for about 20-25% of the total; among these primary and secondary hypogonadisms are the most frequent and they are to be managed with causal treatments and androgen replacement therapy. Therefore, androgen treatments are not useful in functional sex disorders and they may be at risk on prostatic tissue. Andropause is related to a progressive reduction of testicular function, principally due to vascular disorders, with low-normal androgen levels. On the basis of these observations it is underlined that in the human species the androgen presence is a necessary but not sufficient condition for a correct sex function.