Downregulation of androgen, estrogen and progesterone receptor genes and protein is involved in aging-related erectile dysfunction.

Abstract

We hypothesize that downregulation of sex hormone receptors (androgen, estrogen and progesterone receptors) is involved in aging-related erectile dysfunction. To test this hypothesis, we investigated the expression of sex hormone receptors in penile crura of aging rats. A total of 40 rats were divided into four groups based on age (6, 12, 18 and 24 months), and the erectile function was analyzed by the measurement of intracavernous pressure. Gene and protein expressions of sex hormone receptors were analyzed by RT-PCR and immunostaining, respectively. The mean intracavernous pressures of 6-, 12-, 18- and 24-month-old rats were 110.1, 89.6, 73.5 and 42.7 cm H(2)O, respectively. Gene and protein expressions for androgen receptor, estrogen receptor-beta and progesterone receptor were present in similar levels in 6-, 12- and 18-month-old rat crura, but significantly lower or absent in 24-month-old crura. This is the first study to demonstrate that downregulation of sex hormone receptors in aging rat crura is associated with erectile dysfunction.