Oxidative and nitrosative stress in serum of patients with Parkinson's disease.

Parkinson's disease (PD) is one of the common neurodegenerative disorders. Oxidative stress is considered as a contributing factor to the development of PD. The present study aims to investigate serum oxidative stress status in patients with PD. Oxidative stress was assessed by measuring serum nitric oxide levels, lipid hydroperoxide concentrations, and nitric oxide synthase activity. In addition, total serum antioxidant capacity (TAC) was evaluated using the serum 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) free-radical scavenging method in 32 patient with Parkinson's disease and 32 control subjects. Our results indicated that serum nitric oxide and lipid hydroperoxide levels were significantly lower in patients with PD than controls. Moreover, nitric oxide levels were found to be negatively correlated with Unified Parkinson's Disease Rating Scale (UPDRS). However, no statistical difference was observed in total serum antioxidant capacities and nitric oxide synthase activities between patients and controls. The present study indicates that although antioxidant capacity was not changed, lipid hydroperoxide (LPO) level was found decreased. This might show pre-oxidative process in these patients. In addition, decreased nitric oxide (NO) level and negative correlation observed between NO level and disease rating scale implicated a role for NO in the disease process.