Beneficial antioxidant properties of betaine against oxidative stress mediated by levodopa/benserazide in the brain of rats

The present study was designed to evaluate antioxidant effects of betaine in the brain following administration of levodopa and benserazide, which are routinely used in the treatment of Parkinson's disease. Sprague-Dawley male rats were divided into levodopa (LD), Betaine (Bet.), levodopa plus betaine (LD/Bet.), levodopa plus benserazide (LD/Ben.), levodopa plus betaine-benserazide (LD/Bet.-Ben.) and control groups. The experimental groups received LD 300 mg/kg, Bet. 1.5 % w/w of the total diet, Ben. 75 mg/kg and distilled water to controls for 10 consecutive days, orally. The concentration of plasma total homocysteine significantly increased in LD/Ben.-treated rats when compared to the other groups. Brain glutathione peroxidase (GPx) activity and glutathione content both elevated with betaine treatment in LD/Bet. and LD/Bet.-Ben groups. Superoxide dismutase activity was also higher in controls and betaine-treated rats in comparison with LD and LD/Ben. groups. Likewise, catalase activity significantly increased in control and betaine groups when compared to LD- and LD/Ben.-treated rats. In contrast, brain lipid peroxidation significantly increased in response to LD and LD/Ben. treatments. Regarding metabolism of LD in peripheral tissues, serumic dopamine concentration significantly increased in LD-treated rats in comparison with LD/Ben. group. The present results show beneficial antioxidant and methyl donor properties of betaine versus oxidative stress and hyperhomocysteinemia induced by levodopa and benserazide in an animal model.