Detrusor Underactivity Model in Rats by Conus Medullaris Transection

The goal of the presented protocol was to establish a detrusor underactivity (DU) model in the rat through conus medullaris transection. Laminectomy was performed in a total of 40 female Wistar rats (control group: 10 rats; test group: 30 rats) weighing 200-220 g, and the conus medullaris was transected at the L4‒L5 level in the test group. All the rats were housed and fed under the same environmental conditions for six weeks. In the test group, urine voiding was performed twice daily for six weeks, and mean residual urine volume was recorded. A cystometrogram was performed in both groups. Maximum cystometric capacity (MCC), detrusor opening pressure (DOP), and compliance of the bladder were recorded and calculated. The test group showed significant urinary retention after the surgery, both during and after the spinal shock. However, no abnormality was observed in the control group. When compared to the control group, the MCC and compliance of bladder in the test group was significantly higher than that of the test group (3.24 ± 2.261 mL versus 1.04 ± 0.571 mL; 0.43 ± 0.578 mL/cmH2O versus 0.032 ± 0.016 mL/cmH2O), whereas DOP in the test group was lower than control (20.28 ± 14.022 cmH2O versus 35 ± 13.258 cmH2O). This method of establishing an animal model of DU by the conus medullaris transection offers an excellent opportunity to understand DU's pathophysiology in a better manner.