Comparative study of hydrogen peroxide- and 4-hydroxy-2-nonenal-induced cell death in HT22 cells

Several studies have indicated that lipid peroxidation often occurs in response to oxidative stress, and that many aldehydic products including 4-hydroxy-2-nonenal (HNE) are formed when lipid hydroperoxides break down. In order to clarify the mechanism of oxidative stress-induced neuronal death in the nervous system, we investigated H2O2- and HNE-induced cell death pathways in HT22 cells, a mouse hippocampal cell line, under the same experimental conditions. Treatment with H2O2 and HNE decreased the viability of these cells in a time- and concentration-dependent manner. In the cells treated with H2O2, significant increases in the immunoreactivities of DJ-1 and nuclear factor-κB (NF-κB) subunits (p65 and p50) were observed in the nuclear fraction. H2O2 also induced an increase in the intracellular concentration of Ca2+, and cobalt chloride (CoCl2), a Ca2+ channel inhibitor, suppressed the H2O2-induced cell death. In HNE-treated cells, none of these phenomena were observed; however, HNE adduct proteins were formed after exposure to HNE, but not to H2O2. N-Acetyl-l-cysteine (NAC) suppressed both HNE-induced cell death and HNE-induced expression of HNE adduct proteins, whereas H2O2-induced cell death was not affected. These findings suggest that the mechanisms of cell death induced by H2O2 different from those induced by HNE in HT22 cells, and that HNE adduct proteins play an important role in HNE-induced cell death. It is also suggested that the pathway for H2O2-induced cell death in HT22 cells does not involve HNE production.