Effect of estrogen on urethral function and nerve regeneration following pudendal nerve crush in the female rat

Purpose: We tested the hypothesis that estrogen promotes improvement in urethral function and nerve regeneration following bilateral pudendal nerve crush in ovariectomized female rats. Materials and Methods: A total of 52 female rats underwent ovariectomy 6 days before bilateral pudendal nerve crush. Estrogen and sham capsules were subcutaneously implanted at the time of nerve crush in 16 and 14 of these rats, respectively, while 22 served as unoperated controls. Seven days following nerve crush urethral LPP testing was performed using urethane anesthesia. Spinal cord sections containing motoneurons of Onufrowicz's nucleus were subjected to in situ hybridization to detect the expression of beta(II) tubulin mRNA, a marker of the neuroregenerative response. Results: Mean LPP +/- SEM was significantly decreased after pudendal nerve crush in sham treated animals compared to unoperated controls (32.1 +/- 6.8 vs 54.4 +/- 11.6 cm H(2)O). Rats with an estrogen implant had an LPP of 42.5 +/- 16.8 cm H(2)O, which was significantly greater than rats given sham implants and significantly less than unoperated controls. Rats that received an estrogen implant had increased beta(II) tubulin mRNA expression compared to those that received a sham implant. Conclusions: The results of this research suggest that estrogen given at the time of pudendal nerve crush promotes and facilitates the recovery of urethral function and an increase in the nerve regenerative response. Future studies will include the investigation of molecular pathways activated by estrogen in response to peripheral nerve injury.