Effect of long-term hyperprolactinemia on the prolactin receptor content of the rat ventral prostate

The rat ventral prostate contains prolactin receptors, and during sexual maturation prolactin stimulates the growth of this gland. The aim of the present investigation was to evaluate whether prolactin is involved in the regulation of the number of its own receptor sites in the rat ventral prostate. To this end, the content of prolactin receptors was estimated in prostate membranes of control and chronically hyperprolactinemic rats both before and after in vitro desaturation with 4 M MgCl2. Hyperprolactinemia resulted in a 40% increase in the number of available prolactin receptors (P less than 0.05). In vitro desaturation of receptors resulted in loss of 84% of protein and 36 +/- 6% and 52 +/- 6% of prolactin receptors from ventral prostate membranes of control and hyperprolactinemic rats respectively (P less than 0.05). We have concluded that the rat ventral prostate membranes are not suited to in vitro desaturation of prolactin receptors with MgCl2. From the increase in the number of available prolactin receptors after hyperprolactinemia we have concluded that prolactin is involved in the regulation of the number of its own receptors in the rat ventral prostate.