Antioxidant enzymes activity in subjects with Parkinson's disease under L-DOPA therapy

Introduction: Age and oxidative stress represent two endogenous significant risk factors for developing Parkinson's disease (PD). The selective loss of dopaminergic neurons in substantia nigra pars compacta (SNPC) leads to an increased turnover of dopamine by surviving neurons and an excessive production of reactive oxygen species (ROS) by enzymatic or chemical transformation of this neurotransmitter. Levodopa (L-DOPA), a dopamine precursor, represents the most effective medication for controlling the motor symptoms in PD. Some studies showed that this drug could enhance oxidative stress and may be responsible for the degeneration of residual dopamine neurons in subjects with PD. Aim: Therefore, the aim of this study was to evaluate the activity of two key enzymes of the antioxidant defense system: superoxide dismutase (SOD) and glutathione peroxidase (GPx), and to investigate if these activities are correlated with the daily L-DOPA dose.