The Role of Testosterone and Estradiol on the Morphological and Histological Changes of Benign Prostatic Hypertrophy in Sprague Dawley Rats

Background: The prostate, the key secondary male reproductive organ, serves an important function of alkalizing seminal fluid and protecting genetic information in the acidity of the vaginal tract. As males age, the most common urologic condition manifests as an enlargement of the prostate known as benign prostatic hypertrophy (BPH). The purpose of this study is to examine the relationship between hormonal regulation and enzymatic activity of the proton-pump, H-K-ATPase (HKA), on the effects of morphological changes in BPH. Methods: The experiments were designed to test the effects of the primary male androgen, testosterone propionate (TP), as well as the primary male estrogen, estradiol (E2). Sprague-Dawley outbred rats were divided into three groups; control group, TP group, and TP-E2 group. Both the TP and the E2 were diluted in vegetable oil and covered to eliminate light exposure. Subcutaneous injections of TP at 3 mg/mL were administered to induce BPH in rats. After 6 weeks, differing dosages (60 µg and 120 µg) of E2 were administered subcutaneously. The prostate specimens were then dissected after euthanasia of the rats under anesthesia and the organ quotient measured. Some specimens were fixed and embedded in paraffin using histopathological methods, in order to measure the size of the glandular cavity and prostate epithelia. Other specimens were used to run SDS-PAGE and Western blot analysis for HKA activity using anti-HKA alpha antibody. Results: The data indicate significant hypertrophy of the luminal cells in rats with 3 mg TP (11/15/14) compared to the control (P-value \u3c 0.005). Furthermore, the experimental group with 3 mg TP (11/13/14) and 60 µg E2 (1/13/15) showed inhibitory effects compared to TP-induced BPH (P-value \u3c 0.005). Lastly, the experimental group with 3 mg TP (11/13/14) and 120 µg E2 (1/13/15) showed significant inhibitory effect compared to TP-induced BPH (P-value \u3c 0.005). However, the inhibitory effects of the 60 µg E2 group were more significant than the inhibitory effects of the 120 µg E2 group, suggesting the importance of maintaining a proper E2:TP ratio. Western blot analysis shows down-regulation of specific bands for HKA alpha subunit at ~97 kDa for TP-induced BPH. Conclusions: Both the induction and inhibition of hypertrophic cells suggests that the prostate is under hormonal regulation. Furthermore, the proper E2:TP ratio plays a crucial role in the pathogenesis of BPH. If the optimal ratio is not maintained, BPH may occur. Decreased HKA alpha expression in TP-induced BPH suggests that such enzymatic activity is androgen dependent. Such knowledge of E2:TP ratio in humans may help to prevent or cure BPH in the future