Effects of sex hormones on cell proliferation and apoptosis in the urinary bladder muscle of ovariectomized rat

Objective: To reveal the exogenous effects of sex hormones on cell proliferation and apoptosis in the detrusor muscle of ovariectomized rat urinary bladder. Materials and Methods: Proliferating cell nuclear antigen (PCNA) and in-situ apoptosis detection kit were used to evaluate cell proliferation and death in the detrusor muscle of castrated female rats after 1 day, 3 days, and 7 days of supplementary sex steroid hormone administration, including estrogen, progesterone, and testosterone. The percentage of cells positive for PCNA (proliferative index) and for apoptosis (apoptotic index) in various groups was calculated. Results: When compared to the group of bilateral ovariectomy without hormonal supplementation, the groups given 3 days and 7 days of estrogen supplementation (p=0.031 and p=0.005, respectively) and the group given 7 days of combined supplementation with estrogen and progesterone (p=0.044) had a significant increase in the proliferative indices. A significant decrease of apoptotic index was found in the group given 7 days of estrogen supplementation when compared to bilateral ovariectomy without hormonal supplementation (p=0.035). Conclusions: Exogenous estrogen supplementation stimulates proliferation and slows down apoptosis in the detrusor muscle of ovariectomized rat urinary bladder, an effect not counteracted by concomitant use of progesterone. Our results may have clinical implications for estrogen supplementation in offering benefits to menopausal women with lower urinary tract syndromes, based on evaluating the relationship between cell apoptosis and cell proliferation.