Reactive oxygen species and the protective effects of glutathione and N‐acetyl cysteine on mercuric chloride toxicity in Neuro‐2A Cells.

Abstract

The present study was designed to investigate reactive oxygen species (ROS), which are generated by mercuric chloride (HgCl2) in Neuro 2A cells, and to determine the protective effects of various antioxidants on Neuro‐2A cells. HgCl2 was shown to produce 1.9M and 9.2M hydrogen peroxide (H2O2) at 5mM and 10mM HgCl2, respectively. N‐acetyl‐cysteine (NAC) and reduced glutathione (GSH) were shown to reduce H2O2 and provide strong antioxidant properties, which may account for their added protective effect in HgCl2 toxicity. Superoxide increased at low concentrations of HgCl2 (1M to 5M) up to 388% to 450% compared control. Pretreatment with NAC, protected the Neuro‐2A in a dose dependent manner to 74% versus the LD10 value for HgCl2 at 5M, while GSH and CYS provided 95% and 48% protection, respectively, against HgCl2 LD10. Superoxide dismutase (SOD) did not significantly provide protective effects against HgCl2; however it reduces superoxide production slightly, suggesting that H2O2 was partially produced intracellularly. These results demonstrate that H2O2 and superoxide are generated in response to low levels of HgCl2. The antioxidant properties of GSH and NAC which are utilized in GSH synthesis and reduce H2O2 production effectively protect the Neuro‐2A cell from the toxicity of HgCl2. (Supported by a NIH grant NCRR: RR 03020)