THE EXPRESSION OF RECEPTORS FOR ESTROGEN AND EPITHELIAL GROWTH-FACTORIN THE MALE RABBIT PROSTATE AND PROSTATIC URETHRA FOLLOWING CASTRATION

In the lower urinary tract of the male rabbit, estrogen receptors (ERs ) are restricted to the urethra and the prostatic stroma. At present, the function of ERs in these tissues is not known. Epithelial growth f actor (EGF) stimulates proliferation of epidermal and epithelial tissu es, and several animal studies have indicated that EGF is regulated by estrogen. On this background, we have studied the effect of castratio n on the expression of ERs and EGF receptors in the rabbit prostatic u rethra and prostate. Twelve male rabbits were studied fourteen days af ter castration, and eight normal rabbits were included as controls. In the control group, ERs were found in the urothelial lining and lamina propria of the prostatic urethra, and in the prostatic stroma. EGF re ceptors were demonstrated in the epithelial lining of the prostatic ur ethra and the glandular epithelium of the prostate. Following castrati on, the expression of ERs, assessed as the increase in the number of p ositively stained specimens, increased significantly in the lamina pro pria of the prostatic urethra and the prostatic stroma. EGF receptor e xpression increased significantly in the epithelial lining of the pros tatic urethra. In the prostate, the increase was not significant. The results give no support to the view that ERs play role in the regulati on of EGF receptors in the rabbit prostatic urethra nor the prostate.