The production of nerve growth factor by human bladder smooth muscle cellsin vivo and in vitro

Objective To measure the concentrations of nerve growth factor (NGF) in tis sue biopsies taken from subjects with a normal bladder and from patients di agnosed to have idiopathic detrusor instability (associated with a reductio n in the density of motor nerves), and to use an in vitro model to study th e mechanisms of NGF expression. Materials and methods Biopsy specimens were obtained during endoscopic and open surgery from patients undergoing routine bladder surgery. The patients were divided into two categories based upon urodynamic characterization. T he NGF content in samples from 11 normal bladders and seven idiopathic unst able bladders were measured using an enzyme-linked immunosorbent assay. The mechanisms influencing net NGF production were explored using detrusor cel ls in vitro. Results The mean (SEM) NGF content was significantly higher in unstable tis sues, at 0.96 (0.05) pg/mu g protein, than in the normal bladder, at 0.53 ( 0.05) pg/mu g protein. In the cell model, acetylcholine (10 mu mol/L), nora drenaline (1 and 10 mu mol//L) and ATP (1 mu mol/L) caused a significant in crease in net NGF production; acetylcholine at 1 mu mol/L had no effect. Di rect stimulation of protein kinase C (PKC) by phorbol ester (33 ng/mL) or e levation of cAMP using forskolin (10 mu mol/L) increased NGF, suggesting th at at least two intracellular pathways (PKC- and PKA-dependent) are involve d. The expression of c-Fos was increased by phorbol 12-myristate 13-acetate added before NGF, suggesting that c-Fos may be involved in regulating NGF production. Conclusion These data suggest a role for NGF in the physiology and pathophy siology of the human bladder, and indicate some of the possible mechanisms which might regulate NGF production.