Role of androgens in female genital sexual arousal: receptor expression, structure, and function.

In women, androgens modulate the physiological function of many reproductive and sexual organs, including the ovaries, uterus, vagina, oviducts, clitoris, and mammary gland. In this article, we review the mechanisms of androgen action and discuss new data on the effects of androgens in vaginal and clitoral tissues. In this study, we characterized the androgen receptor expression in rabbit vaginal tissues from control and ovariectomized animals treated with or without androgen replacement therapy. We investigated the effects of androgen deprivation and replacement on the expression and activity of nitric oxide synthase and arginase and on vaginal smooth muscle contractility. Androgens enhanced nitric oxide synthase activity and down-regulated arginase activity in proximal vagina. Estrogens down-regulated nitric oxide synthase activity and increased arginase activity in distal vagina. Androgens facilitated vaginal smooth muscle relaxation to electric field stimulation and vasoactive intestinal polypeptide, whereas estrogens attenuated vaginal tissue relaxation to electric field stimulation and to vasoactive intestinal polypeptide. These observations suggest that androgens may play an important role in modulating the physiology of vaginal tissue and contribute to female genital sexual arousal.