Role of urothelial nerve growth factor in human bladder function

Aims: To test whether nerve growth factor (NGF) concentration in human bladder urothelium/suburothelium is related to detrusor overactivity (DO), bladder sensation, detrusor contractility, or other aspects of lower urinary tract function. Materials and Methods: Concentration of NGF was measured (using ELISA) in superficial bladder biopsies from 27 women (mean age 52 years, range 22-82) after comprehensive videourodynamics and bladder diary. Approximately half (12/27) showed clear DO and half did not. Results: There was no evidence for increased NGF concentration in subjects with DO (association negative by Mann-Whitney test, P = 0.23). NGF was not significantly associated with two measures of detrusor contractility (Spearman's r = -0.29, P = 0.17; r = -0.20, P = 0.33); nor with four measures inversely related to sensation: volume at strong desire to void and maximum capacity on cystometry (r = -0.13, P = 0.53; r = -0.23, P = 0.28), and maximum voided volume and mean daytime voided volume on bladder diary (r = -0.29, P = 0.16; r = -0.16, P = 0.44). It was significantly associated with 24-hr urine output on bladder diary (Spearman's r = -0.55, P = 0.004). Conclusions: Elevated NGF levels in human urothelium/suburothelium are not strongly associated with DO, detrusor contractility or increased bladder sensation. NGF levels are lower in subjects with higher 24-hr urine output. This observation is consistent with a role for NGF in an active process (trafficking) involved in bladder filling.