Gender difference in the effect of uric acid on striatal dopamine in early Parkinson's disease

Background and purpose: High uric acid (UA) levels have been shown to exert a neuroprotective effect in Parkinson's disease (PD) by inhibiting oxidative stress in the nigrostriatal pathway. However, the association between striatal dopamine activity and UA level has not been clarified. Methods: A total of 213 patients with early PD were enrolled. All patients underwent positron emission tomography using ¹⁸F-N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane and a venous blood test for quantification of serum UA. All patients were stratified into either the lower UA group or the higher UA group using the median UA level. After normalizing the positron emission tomography images, differences in the regional standardized uptake value ratios (SUVRs) were analyzed with a volume-of-interest template. All tested SUVRs were also compared after categorizing patients by gender. Results: The UA affected dopamine transporter SUVRs in different ways by gender. In female patients, the higher UA level group showed a smaller reduction in dopamine transporter uptake in the posterior putamen, whereas there was no such association observed in male patients. Conclusions: Higher UA levels were correlated with higher dopamine transporter uptake in the putamen in female patients with early PD. This finding suggests that UA has a neuroprotective effect, as demonstrated by the relatively preserved striatal dopamine activity in women.