Differential hormonal regulation of estrogen receptors ERα and ERβ and androgen receptor expression in rat efferent ductules

Abstract

Estrogen receptors, in addition to the androgen receptor (AR), are expressed at high levels in efferent ductules of the male reproductive tract and it is now well recognized that estrogen receptor (ER) α is required for the maintenance of normal structure and function of the ductules. However, little is known regarding the hormonal regulation of the receptors themselves in the male. In the present study, efferent ductule ligation and castration, followed by replacement with testosterone, dihydro-testosterone (DHT) or estradiol was used to investigate the relative importance of circulating and luminal sources of steroid for the modulation of ERα, ERβ and AR in rat efferent ductules. Uni- or bilateral castration and ligation did not affect the expression of ERα and ERβ, but bilateral castration caused down-regulation of AR. Replacement with DHT and testosterone alone or in combination with estradiol caused the recovery of AR expression to control levels. A slight recovery of AR was also observed after estrogen replacement. ERα expression was decreased to nearly undetectable levels after estrogen replacement. On the other hand, ERβ did not show evident effects following any of the treatments, suggesting a constitutive expression of this receptor. This differential modulation of the steroid hormone receptors highlights the importance of maintaining a physiological androgen-estrogen balance to regulate the structure and function of efferent ductules in the male.