Prolactin selectively stimulates ornithine decarboxylase in the lateral lobe of the rat prostate.

In androgenized-hypophysectomized rats, ovine prolactin stimulated the activity of the ornithine decarboxylase (ODC) of the lateral lobes, but not the ventral and dorsal lobes of the prostate glands in a time- and dose-dependent fashion. High degrees of enzyme stimulation were associated with significant elevations in the endogenous levels of its product, putrescine. The relative response to prolactin over basal activities was relatively unaffected by indomethacin but decreased with cycloheximide, suggesting that prostaglandins do not mediate the effects of the hormone, but that a high rate of protein synthesis is a prerequisite for its expression. Indomethacin alone significantly increased the basal activity of the enzyme above control levels, suggesting that prostaglandins may normally exert a degree of inhibition on the ODC. The selective activation of the lateral lobe ODC supports previous reports of a differential response of the various prostatic lobes to prolactin, and also provides a convenient biochemical response for examining details of prolactin action on this organ.