Abstract
Although ERβ is known to be expressed at high levels in the rat prostate gland, its regulation is not well understood. Here we examined ER mRNA expression and the effects of testosterone administration in male rats at 1, 4 and 9 weeks of age who were castrated and/or treated with testosterone for a week, and then sacrificed. ERα was the major type of ER expressed in 2 week-old animals while dominant expression of ERβ mRNA was apparent in older age groups. Interestingly while ERβ expression was diminished and ERα mRNA increased in the castrated group, testosterone administration reversed this effect. A time-course study indicated that induction of ERβ mRNA increased within 9 hr and ERα decreased in 2 days after an injection (i.p.) of testosterone. Our results suggested that 1) testosterone up-regulates ER β mRNA expression while ER α is down-regulated; and that 2) great changes in ERα and β expression in the prostate gland during development from the newborn to adult may be due to the influence of testosterone.
