ANDROGEN-INDEPENDENT EFFECTS OF PROLACTIN ON THE DIFFERENT LOBES OF THE IMMATURE RAT PROSTATE

In this study, we have examined the respective roles of androgens and prolactin (Prl) on rat prostate development and function. Hypophysecto mized immature rats, castrated or not after hypophysectomy and treated or not with a 5 Alpha-reductase inhibitor, were used to study the dif ferent aspects of Prl action on the rat prostate and its synergy with androgens in vivo. Using Northern blot analysis and quantitation of pr ostatic mRNAs, we have shown that Prl significantly increases the stea dy-state levels of transcripts coding for several lobe-specific protei ns: the C3 subunit of prostatein, probasin, and RWB. We have confirmed these observations in vitro, on explants of immature rat prostate tre ated with either saline, Prl, or testosterone. In addition, we have de monstrated by a nuclear run-on assay that Prl significantly enhances t he transcription rate of the C3 gene in the rat prostate. We conclude that the effects of Prl concern all lobes of the organ and are, at lea st in part, androgen-independent. Moreover, Prl is able, via an androg en-independent pathway, to increase the rate of transcription of the C 3 gene, one of the major products of the rat prostate.