Effect of Long-Term Estrogen Replacement on Bladder Function in Old Female Rats

The effects of estradiol (E2) on urodynamic parameters were studied with twenty 16-month-old female Wistar rats. They were divided into 4 groups, i.e., Group I: untreated; Groups II and III: treated with E2 for 4 and 8 weeks, respectively; Group IV: treated with a placebo for 8 weeks. After treatment, we measured their plasma E2 levels, and recorded their voiding behavior for 24 h. Cystometry was performed and urodynamic parameters were analyzed. Particularly, bladder capacity as well as voided volume and frequency were surveyed. The results obtained were compared among groups. Levels of bladder capacity in the E2-replaced groups (Groups II, 0.52 ± 0.14 mL and Groups III, 0.58 ± 0.09 mL) were significantly (P < 0.05) higher than in the other groups (Group I, 0.38 ± 0.09 mL and Group IV, 0.40 ± 0.11 mL) respectively. The average voided volume was significantly (P < 0.05) higher in the E2-replaced groups (Groups II, 1.06 ± 0.22 mL and Groups III, 1.01 ± 0.16 mL) than in Group IV (0.79 ± 0.15 mL), respectively. Concerning the number of daily micturition per day, a significant difference (P < 0.05) was observed only between Group III (14.2 ± 2.7) and Group IV (18.8 ± 3.7). This suggests that E2-replacement therapy positively affects bladder function.