Nerve growth factor and vanilloid receptor expression, and detrusor instability, after relieving bladder outlet obstruction in rats

OBJECTIVE: To investigate mRNA expression for nerve growth factor (NGF) and vanilloid receptor TRPV1 in the bladder after relieving bladder outlet obstruction (BOO), and to correlate changes with functional changes of the bladder. MATERIALS AND METHODS: Temporary BOO was induced by partial urethral ligation in 40 male Wistar rats. After 3 weeks the obstruction was removed and the rats assessed by cystometry 3 weeks later. The bladder body of each rat was then removed, and NGF and TRPV1 mRNA expression measured by the reverse transcription-polymerase chain reaction. Fifteen sham-operated rats served as controls. RESULTS: Based on the cystometry, 10 of the 40 experimental rats were judged to have an unstable bladder, and the remaining 30 to have normal bladder function. The mean bladder weight in the normal and unstable groups was higher than in the control group, and there was no significant difference between the normal and unstable groups. The bladder contraction pressure was similar in the three groups but the mean contraction interval was markedly shorter in the unstable than in the control and normal groups (P < 0.05). The mRNA expressions of NGF and TRPV1 were higher in the unstable than in the control and normal groups. CONCLUSIONS: NGF and TRPV1 were apparently increased in unstable bladder tissue after relieving BOO; these changes may be related to irritative symptoms after correcting BOO.