Effects of Pituitary Grafts on Testosterone Stimulated Growth of Rat Prostate

Abstract

The effect of prolactin and testosterone on the lateral prostatic growth was studied in Fischer 344 rats. Two pituitaries from adult female rats/animal were grafted under the renal capsule of 30-day-old castrated males. The control castrates received surgical exposure of the kidney but no grafts. Silastic tubing either empty or packed with crystalline testosterone for 0.5, 2.0 or 4.0 cm of its length was implanted s.c. into each rat immediately following the grafting or sham operation. Three weeks later, all animals were sacrificed. The average serum prolactin in pituitary-grafted animals was 430 ng/ml. In nongrafted controls, the average was 15–50 ng/ml. In rats bearing pituitary grafts and 0.5 cm of testosterone tubing, lateral prostate weight was 88% greater than in controls given 0.5 cm of testosterone tubing alone. In animals with grafts and 2.0 cm testosterone tubing, the increase in lateral prostate weight was only 27%. Furthermore, in those given 4.0 cm testosterone tubing, lateral prostate weights in grafted and control animals were not significantly different. Pituitary grafts did not increase the weight of ventral prostate, dorsal prostate, seminal vesicle or coagulating gland beyond that stimulated by the testosterone tubing. Results demonstrated an inverse relationship between circulating testosterone levels and the degree of synergism with prolactin on the weight of the lateral prostate in rats.