Alterations of nerve-growth factor and p75NTR expressions in urinary bladder of fructose-fed obese rats

The study investigated the effects of metabolic syndrome on urinary bladder nerve-growth factor (NGF) and p75NTR expression in fructose-fed obese rats. Age-matched male Wistar rats were divided into four groups; group I: normal control rats; group II: 6-week fructose-fed rats (FR); group III: 9-week FR; and group IV: 12-week FR. In vivo cystometry under anesthesia was performed. In vitro bladder NGF levels were measured by enzyme-linked immunosorbent assay (ELISA). Expressions of the mRNAs that encoded NGF and NGF receptor p75NTR in control and 9-week FR bladder were studied using the method of reverse transcription combined with polymerase chain reaction (RT–PCR).The three groups of FR showed significant increases in body weight, blood pressure, plasma glucose, insulin and triglyceride levels when compared to control rats. The bladder NGF levels in the 9-week and 12-week FR were significantly lower than the control (66.8 ± 5.4, 49.4 ± 7.1 and 95.2 ± 6.5 pg/μg protein; p < 0.05 and p < 0.01 respectively, for n = 8 in each group). The bladder emptying function was deteriorated in these two groups of FR as shown by the significantly increased residual volume and decreased emptying fraction. The mRNA expressions of bladder NGF and p75NTR in the 9-week FR were significantly decreased when compared to the control group (p < 0.05 and p < 0.001 respectively, n = 8 in each group). In conclusion, long-term metabolic syndrome in FR significantly decreases bladder NGF and p75NTR expression. These alterations are associated with deterioration in bladder emptying function.