4-Hydroxynonenal induces oxidative stress and death of cultured spinal cord neurons

Primary spinal cord trauma can trigger a cascade of secondary processes lea ding to delayed and amplified injury to spinal cord neurons. Release of fat ty acids, in particular arachidonic acid, from cell membranes is believed t o contribute significantly to these events. Mechanisms of fatty acid-induce d injury to spinal cord neurons may include lipid peroxidation. One of the major biologically active products of arachidonic acid peroxidation is 4-hy droxynonenal (HNE). The levels of HNE-protein conjugates in cultured spinal cord neurons increased in a dose-dependent manner after a 24-h exposure to arachidonic acid. To study cellular effects of HNE, spinal cord neurons we re treated with different doses of HNE, and cellular oxidative stress, intr acellular calcium, and cell viability were determined. A 3-h exposure to 10 mu M HNE caused similar to 80% increase in oxidative stress and 30% elevat ion of intracellular calcium. Exposure of spinal cord neurons to HNE caused a dramatic loss of cellular viability, indicated by a dose-dependent decre ase in MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-su lfophenyl)-2H-tetrazolium, inner salt] conversion. The cytotoxic effect of HNE was diminished by pretreating neurons with ebselen or N-acetylcysteine. These data support the hypothesis that formation of HNE may be responsible , at least in part, for the cytotoxic effects of membrane-released arachido nic acid to spinal cord neurons.