Higher plasma urate level is reported to be associated with a reduced risk and slower progression of Parkinson's disease (PD). In this study, we explored the effects of urate on dopaminergic neurons in nigrostriatal pathway in the 6-hydroxydopamine (6-OHDA) unilaterally lesioned rats. Uric acid (UA), when given twice daily at 200 mg/kg intraperitoneally for 10 consecutive days, elevated urate (the anionic form of UA) in plasma and striatum by 55% and 36.8%, respectively, as compared with vehicle group. This regimen of UA was found to ameliorate the behavioral deficits, dopaminergic neuron loss as well as dopamine depletion in the nigrostriatal system. Moreover, UA administration was capable of increasing glutathione level and superoxide dismutase activity while decreasing malondialdehyde accumulation in striatum. In addition, the phosphorylation of both protein kinase B (Akt) and glycogen synthase kinase 3 beta (GSK3b) in the lesioned striata of 6-OHDA-lesioned rats was dramatically reduced as compared with sham-operated rats. This reduction was attenuated in the Parkinsonian rats receiving UA treatment. Similarly, in vitro findings showed that UA alleviated the decrease in Akt activation and the increase in GSK3b activity caused by 6-OHDA. Furthermore, neuroprotection by urate and its regulation on GSK3b phosphorylation at Ser9 was found to be abolished in the presence of PI3K inhibitor. Therefore, our findings demonstrated that urate was able to protect dopaminergic neurons in rat nigrostriatal pathway against the neurotoxicity of 6-OHDA, and showed that its beneficial effects may be related to its regulation on Akt/GSK3b signaling.
ObjectivesThe serum concentration of brain-derived neurotrophic factor (BDNF) was compared among patients with Parkinson’s disease (PD), patients with essential tremor (ET), and healthy participants, and its association with clinical features of PD and ET was assessed.MethodsDemographic and clinical data were collected from 60 patients with PD at different clinical stages, 60 patients with ET, and 60 controls. All participants’ serum BDNF concentrations were measured. Their motor abilities and activity were assessed by the Unified PD Rating Scale and the Hoehn and Yahr (H-Y) staging scale.ResultsSerum BDNF was significantly lower in patients with PD than in patients with ET and controls. BDNF decreased only in the early disease stages (H-Y stages I and II), but increased markedly in the advanced stages (H-Y stages III–V). There was no significant difference between patients with ET and controls. The BDNF concentration was negatively correlated with age at PD onset and positively associated with disease duration, severity of PD symptoms, and treatment with L-DOPA.ConclusionsA low serum BDNF concentration may serve as a biomarker in the early stages of PD, whereas a high concentration with PD progression may be due to treatment with L-DOPA in the advanced stages.
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