Protective effects of Vitamin E on endocrine disruptors, PCB-induced dopaminergic neurotoxicity

The protective effect of an antioxidant, Vitamin E (dl-α-tocopherol, 100 mg/kg/day, 8 days p.o. in vivo and 10 and 50 μM in vitro) was tested against PCB-induced neurotoxicity. In vivo studies: Microdialysis was used to investigate changes in the striatal extracellular dopamine level and in p-nNOS expression in PCB-treated (Aroclor 1254, 10 μg/ml, 2 μl/min, 5 h; 6 μg was infused by microdialysis probe) rats. In vitro studies: Cell viability and levels of p-nNOS expression were observed in PCB-treated (Aroclor 1254, 5 μg/ml) immortalized dopaminergic cell line (CATH.a cells). Results: Treatment with PCB: (1) decreased the extracellular dopamine level in rat striatum, (2) increased p-nNOS expression both in rat striatal tissue and in CATH.a cells, (3) reduced the cell viability of, and (4) increased LDH release by CATH.a cells. However, Vitamin E showed a protective effect against PCB-induced toxicity and downregulation of the extracellular dopamine level. These results indicate that Vitamin E may have neuroprotective effects by inhibiting PCB-induced nNOS phosphorylation.