Induction of specific gelatinolytic proteinases in the lateral prostate of rats by ectopic pituitary grafts.

Activities of plasminogen activator (PA) and gelatinolytic proteinase in the ventral, lateral, and dorsal lobes of the prostate were examined in rats with hyperprolactinemia, which was induced by implantation of ectopic pituitary grafts under the renal capsule. Weight and total DNA content of the lateral lobe increased significantly in rats receiving two pituitary glands as compared with values for the initial untreated group and the muscle-implanted control animals. No change in specific activity of PA was observed in any prostatic lobe for animals of different treatment groups. However, there was a lateral lobe-specific induction of gelatinolytic proteinase activity in pituitary-grafted rats. Two Ca(2+)-independent proteinase activities of approximately 26-28 and 88 kDa, and three calcium-sensitive proteinase activities of 59, 64, and 76 kDa were found in zymograms of lateral prostate extracts of the untreated initial group and the muscle-grafted control. The lateral prostate proteinase pattern of pituitary-grafted animals demonstrated intense activities of approximately 51, 53, 64, 76, and 135 kDa as well as weaker activities of 40, 43, 59, 85, 93, 105, and 125 kDa. Many of these proteinase activities were present in the secretion of the lateral prostate of the untreated initial controls, suggesting that hyperprolactinemia promotes secretion in the lateral prostate. Those proteinase activities that were not in the secretion were probably of intracellular origin and may play a role in cellular remodeling. Castration resulted in a decrease in activities of these proteinases, and this decrease was observed whether the pituitary grafts were retained or removed.