[Effects of delivery and oophorectomy on urethral collagen: an experimental study].

OBJECTIVE Stereological evaluation of the concentration of type I and III collagen fibers in the urethral tissue of rats subjected to simulated labor and oophorectomy. To compare the concentrations of collagen between oophorectomized and non-oophorectomized rats. MATERIAL AND METHOD Sixty adult Wistar rats were divided into six groups. A group made up of virgin rats was used as control group and another group was made up of oophorectomized rats. Two groups underwent vaginal distention for 30 and 120 minutes, respectively. The two other groups were subjected to the same distension periods, followed by oophorectomy. Sixty days later, euthanasia and removal of urethral tissue was carried out for stereological analysis of type I and III collagen after staining with hematoxylin and eosin and picrosirius red. RESULTS A decrease in estrogen levels was observed in the oophorectomized rats. There was a reduction of type III collagen in the oophorectomized control group compared to the control group when analyzed independently. No significant differences were observed among the other groups. Type I collagen decreased in all groups compared to the control group. However, in the prolonged vaginal distension and oophorectomy group, these fibers increased. CONCLUSION In normal rats, simulation of labor does not alter the collagen III levels. In hypoestrogenic rats, the concentration of collagen type I and III decreased, except in those undergoing prolonged labor simulation in which collagen I increased.