Increased Urinary Nerve Growth Factor as a Predictor of Persistent Detrusor Overactivity After Bladder Outlet Obstruction Relief in a Rat Model

PURPOSE: We evaluated urinary nerve growth factor as a predictive factor for persistent detrusor overactivity after bladder outlet obstruction relief in a rat model. MATERIALS AND METHODS: A total of 50 female Sprague-Dawley(R) rats were divided into 2 groups, including 10 sham operated controls and 40 with bladder outlet obstruction. Obstruction was induced by partial urethral ligation and relieved by ligation removal after 3 weeks. Voided urine was collected before bladder outlet obstruction at time 1, 3 weeks after obstruction onset at time 2 and 3 weeks after obstruction relief at time 3. Cystometry was done in awake rats at times 2 and 3. Bladder tissue was harvested at time 3. Urinary and bladder tissue nerve growth factor was measured by enzyme-linked immunosorbent assay with results adjusted based on creatinine concentration. RESULTS: In 16 rats in which detrusor overactivity disappeared after bladder outlet obstruction relief (group 1) urinary nerve growth factor/creatinine significantly increased from time 1 to 2 and significantly decreased from time 2 to 3 (p = 0.001 and 0.003, respectively). In 8 rats with persistent detrusor overactivity despite obstruction removal (group 2) urinary nerve growth factor/creatinine significantly increased from time 1 to 2 but did not change from time 2 to 3 (p = 0.012 and 0.123, respectively). These rats with persistent detrusor overactivity also had significantly higher urinary nerve growth factor/creatinine at time 1 than controls and group 1 (p = 0.015 and 0.005, respectively). CONCLUSIONS: Changes in urinary nerve growth factor may reflect detrusor overactivity, as diagnosed on 2 consecutive cystometries. Increased urinary nerve growth factor before bladder outlet obstruction may predict persistent detrusor overactivity after obstruction relief.