Chronic treatment with epidermal growth factor induces growth of the rat ventral prostate.

Abstract

The epidermal growth factor (EGF) system is expressed in the rat prostate, and growth factors from this system induce proliferation in prostate epithelial and stromal cell cultures. The aim of the study was to investigate the possible growth-promoting effects of the system during the hyperplastic growth phase of the prostate in newborn rats. Newborn rats were treated for 8 weeks with EGF (150 microg/kg body weight per day), administered as daily subcutaneous injections. Sections of the prostate tissue were examined by a stereological technique to determine tissue composition. Treatment with EGF increased the weight of the ventral prostate, relative to body weight, by 50% compared with placebo (p < 0.005). Neither the dorsolateral prostate, seminal vesicles nor coagulating glands were affected by EGF. Prostate tissue showed a significant increase in the volume of the prostate epithelium, the stroma and the lumen following EGF treatment, in a pattern resembling physiological growth of the ventral prostate. A significant correlation (r = 0.78, p < 0.0001) of the volume fraction of the lumen with the glandular weight of the ventral prostate was seen. Serum testosterone was not affected by chronic EGF administration. EGF selectively induces growth of the ventral lobe of the prostate in newborn rats, in a pattern comparable to normal physiological growth. It may be hypothesized that the physiological growth of the prostate is directly correlated to endogenous activity of the EGF system in the rat prostate gland.