Novel alterations in superoxide dismutase and catalase activities in the female rabbit bladder subjected to hormonal manipulations

Abstract

Objectives: Previous studies have demonstrated that ovariectomy induces reduced blood flow and hypoxia, resulting in free radical damage of the mucosal and smooth muscle compartments of the rabbit urinary bladder, whereas estradiol administration results in angiogenesis and recovery from hypoxia. The current study was designed to investigate the effects of ovariectomy and estradiol replacement on the superoxide dismutase (SOD) and catalase (CAT) activities of the bladder.

Methods: A total of 12 mature female rabbits were divided into three groups of four rabbits each: control, ovariectomy, and ovariectomy with 17-beta estradiol supplementation by subcutaneous slow-release tablet. The bladder body and base of the rabbits were examined after 2 weeks. The bladder body and base were separated into muscle and mucosa, and the tissues were analyzed for SOD and CAT activities.

Results: Quantitative SOD activities for the mucosa and muscle of both bladder body and base increased after ovariectomy when compared with those of controls. Estradiol replacement resulted in a significant decrease in the SOD activities in the body muscle. Ovariectomy caused a decrease in the CAT activities in the bladder tissues, whereas estradiol treatment resulted in significant increases.

Conclusions: These data indicate that ovariectomy induced generation of reactive oxygen species (ROS), as evidenced by the enhanced SOD activity, indicating oxidative stress in the lower urinary tract. Estradiol replacement reversed the effects of ovariectomy; this finding suggests an anti-oxidant effect of estradiol on the bladder.