Rat Estrogen Receptor- and - , and Progesterone Receptor mRNA Expression in Various Prostatic Lobes and Microdissected Normal and Dysplastic Epithelial Tissues of the Noble Rats

Semiquantitative RT-PCR was used to determine if transcripts of the two estrogen receptor (ER) subtypes, ERα and ERβ, and the progesterone receptor (PR) are differentially expressed and/or regulated in the various normal lobes of the Noble (NBL) rat prostate. We found that ERβ mRNA was present at comparable, high levels in all three major prostatic lobes: dorsal (DP), lateral (LP) and ventral (VP) prostate. ERα mRNA was, however, expressed at low levels among the various lobes in the following descending order of abundance: LP>DP>VP. Expression of PR transcript was low and paralleled the expression pattern of ERα mRNA. Treatments of rats with testosterone (T) plus estradiol-17β (E2) (T+E2) or T alone induced no discernible alterations in ERα, ERβ, and PR mRNA levels in the VP, DP and LP, while those with E2 caused a general decline in the expression of all three transcripts. We then studied the expression of the three receptors in the normal and dysplastic epithelium of the dorsolateral prostates (DLPs) of rats treated with T+E2. Comparable levels of ERβ mRNA were found in microdissected dysplastic and normal epithelia. In contrast, significantly higher levels of PR mRNA were present in epithelial samples from dysplastic acini. ERα mRNA was not detected in any of the microdissected epithelial samples. Results from this study suggest that upregulation of PR mRNA expression, likely mediated via ERβ action, is involved in the genesis of T+E2-induced dysplasia in this animal model.