Antioxidative and anti-inflammatory effects of four cysteine-containing agents in striatum of MPTP-treated mice

Objectives Mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were used to examine the neuroprotective effects of n-acetyl cysteine (NAC), s-ethyl cysteine (SEC), s-methyl cysteine (SMC), and s-propyl cysteine (SPC). Methods Each agent at 1 g/L was directly added to the drinking water for 3 wk. Mice were treated by subcutaneous injection of MPTP (24 mg/kg body weight) for 6 consecutive days. The brain from each mouse was quickly removed and the striatum was collected for analyses. Results The MPTP treatment significantly depleted striatal glutathione content, reduced the activity of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase, increased malondialdehyde level, and elevated interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels in striatum (P < 0.05). The pre-intake of NAC, SEC, SMC, and SPC significantly attenuated MPTP-induced glutathione loss, retained the activity of GPX and SOD, diminished oxidative stress, and suppressed MPTP-induced elevation of IL-6 and TNF-α (P < 0.05). MPTP treatment significantly suppressed GPX mRNA expression and enhanced TNF-α mRNA expression (P < 0.05). Compared with MPTP treatment alone, the pre-intake of NAC, SEC, SMC, and SPC significantly elevated GPX mRNA expression and diminished TNF-α mRNA expression (P < 0.05), in which SPC showed the greatest suppressive effect against MPTP-induced TNF-α mRNA expression (P < 0.05). Dopamine and 3,4-dihydroxyphenylacetic acid contents in the striatum were significantly decreased by MPTP treatment (P < 0.05). The pre-intake of four test agents significantly improved MPTP-induced dopamine depletion and increased dopamine/3,4-dihydroxyphenylacetic acid content (P < 0.05). Conclusion These results suggest that these cysteine-containing compounds could provide antioxidative and anti-inflammatory protection for the striatum against the development of Parkinson’s disease.