Multihormonal control of synthesis and secretion of prostatein in cultured rat ventral prostate.

The synthesis and accumulation of prostatein, a major secretory protein of the rat ventral prostate, was examined in organ culture conditions. For the quantitation of this protein in the medium, a sensitive enzyme immunoassay was developed. The rat ventral prostate could be maintained in organ culture in defined medium for at least 2 weeks. Morphologically the changes in explants cultured without hormones resembled those of castration. These involutive changes could be postponed by testosterone and totally prevented by a combination of testosterone, corticosterone, and insulin in the culture medium. Newly synthesized prostatein, studied by fluorography of [35S] methionine-labeled proteins, accumulated only in the presence of testosterone. Its synthesis also took place in cultured prostate derived from castrated rats. Neither corticosterone nor insulin alone could sustain prostatein synthesis. Insulin increased the testosterone-dependent prostatein synthesis in the beginning of culture, but later, inhibition, rather than stimulation, could be noted. Corticosterone increased the testosterone-dependent synthesis of prostatein throughout the culture. The results show that organ culture of adult rat ventral prostate provides an in vitro model for studies of differentiated prostatic function.