Protective Effects of Zonisamide Against Rotenone-Induced Neurotoxicity

Abstract

Zonisamide (ZNS), an antiepileptic drug having beneficial effects also against Parkinson's disease symptoms, has proven to display an antioxidant effects in different experimental models. In the present study, the effects of ZNS on rotenone-induced cell injury were investigated in human neuroblastoma SH-SY5Y cells differentiated towards a neuronal phenotype. Cell cultures were exposed for 24h to 500 nM rotenone with or without pre-treatment with 10-100μM ZNS. Then, the following parameters were analyzed: (a) cell viability; (b) intracellular reactive oxygen species production; (c) mitochondrial transmembrane potential; (d) cell necrosis and apoptosis; (e) caspase-3 activity. ZNS dose-dependently suppressed rotenone-induced cell damage through a decrease in intracellular ROS production, and restoring mitochondrial membrane potential. Similarly to ZNS effects, the treatment with N-acetyl-cysteine (100μM) displayed significant protective effects against rotenone-induced ROS production and Δψm at 4 and 12h respectively, reaching the maximal extent at 24h. Additionally, ZNS displayed antiapoptotic effects, as demonstrated by flow cytometric analysis of annexin V/propidium iodide double staining, and significant attenuated rotenone-increased caspase 3 activity. On the whole, these findings suggest that ZNS preserves mitochondrial functions and counteracts apoptotic signalling mechanisms mainly by an antioxidant action. Thus, ZNS might have beneficial effect against neuronal cell degeneration in different experimental models involving mitochondrial dysfunction.