The aim of this study was to investigate the involvement of inducible nitric oxide synthase (iNOS) in the action of (-)-epigallocatechin-3-gallate (EGCG), a potential neuroprotective agent against Parkinson's disease (PD), and to test for toxicity resulting from high doses of EGCG. EGCG was administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice at two different doses (10mg/kg and 50mg/kg). EGCG treatment reduced the neuronal death rate to less than 50%. The level of iNOS expression in the MPTP group was 20% higher than that seen in the control group, but in the EGCG groups, iNOS expression was reduced to the level observed in the negative control group. The two doses of EGCG were equally beneficial for cell rescue, and no toxicity was observed with the higher dose. Inhibition of iNOS may be an important mechanism underlying the prevention of MPTP toxicity, and EGCG may potentially be a neuroprotective agent against PD.
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