Hormonal effects on blood vessels.

The incidence of cardiovascular disease (CVD) is lower in younger women than in men of the same age, but it increases after menopause, implicating the atheroprotective action of endogenous estrogen. Although observational studies have suggested the efficacy of estrogen therapy in postmenopausal women, placebo-controlled, randomized trials, such as the Women's Health Initiative, have not confirmed effects of estrogen therapy on CVD. Conversely, basic, experimental research has progressed and provided mechanistic insight into estrogen's action on blood vessels. By contrast, the vascular effects of androgens remain poorly understood and have been controversial for a long time. In recent years, an increasing body of evidence has suggested that androgens may exert protective effects against the development of atherosclerosis, at least in elderly men. Epidemiological studies have shown that the incidence of and mortality due to CVD were increased in elderly men with low testosterone levels, although the efficacy of androgen therapy remains unknown. Furthermore, recent experimental studies have demonstrated the direct action of androgens on the vasculature. In this review, we illustrate the effects of sex steroids on the cardiovascular system, focusing on the action of testosterone on the blood vessels.