Experimental study on cytotoxicity of levodopa in Parkinson's disease rat

Objective To study the effects of Levodopa on the abnormal behavior, nigral antioxidation system, mitochondrial respiration-chain function, neurotransmitter metabolism of Parkinson's disease (PD) model rat and its mechanism.Methods The rat models of PD were established through stereotaxic microinjection of 6-hydroxydopamine (6-OHDA). The rats in levodopa group were given levodopa 25 mg/(kg·d) through intragastric administration for 45 days. All the rats’behavior was tested before and after giving medicine. The activity of glutathione peroxidase(GSH-Px) and ROS, contents of malondialdedyde(MDA) and mitochondrial respiratory chain enzyme complex Ⅰ in nigra and the contents of dopamine(DA), homovanillic acid(HVA) and activity of monoamine oxidase-B(MAO-B) in caudate nucleus were assayed after treatment.Results (1) Compared with before treatment, the rotation rate after treatment decreased obviously( P0.01). (2) In levodopa group, GSH-Px activity and mitochondrial respiratory chain enzyme complex Ⅰ level reduced, ROS activity and MDA content increased. The differences were significant compared with the controls (all P0.01). (3) Compared with control group, MAO-B activity in levodopa group increased, DA, HVA contents and DA/HVA ratio increased obviously( P0.05 or P0.01).Conclusion Levodopa may obviously decrease rotation behavior of PD model rats but aggravate oxidative stress of nigra, restrain the activity of mitochondrial respiratory chain.