Inhibition of hydrogen sulfide generation contributes to 1-methy-4-phenylpyridinium ion-induced neurotoxicity.

Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of 1-methy-4-phenylpyridinium ion (MPP(+)). Increasing studies have shown that hydrogen sulfide (H(2)S) is an endogenous antioxidant gas. We have hypothesized that MPP(+)-caused neurotoxicity may involve the imbalance of proportion to this endogenous protective antioxidant gas. The aim of this study is to evaluate whether MPP(+) disturbs H(2)S synthesis in PC12 cells, a clonal rat pheochromocytoma cell line, and whether disturbance of H(2)S generation induced by MPP(+) is an underlying mechanism of MPP(+)-induced neurotoxicity. We show that exposure of PC12 cells to MPP(+) causes a significant decrease in H(2)S generation and results in remarkable cell damage. We find that cystathionine-β-synthetase (CBS) is catalyzed in PC12 cells to generate H(2)S, and that both expression and activity of CBS are inhibited by MPP(+) treatment. Exposure of sodium hydrosulfide (NaHS), a donor of H(2)S, extenuates MPP(+)-induced cytotoxicity and ROS accumulation in PC12 cells, while inhibition of CBS by amino-oxyacetate (AOAA) exacerbates the effects of MPP(+). These results indicate that MPP(+) neurotoxicity involves reduction of H(2)S production, which is caused by inhibition of CBS. This study provides novel insights into cell death observed in neurodegenerative disease such as Parkinson's disease.