Acta Pharmacologica Sinica 2007 March; 28 (3): 315-326; doi: 10.1111/j.1745-7254.2007.00512.x

Aim: To observe the effects of stearic acid against oxidative stress in primary cultured cortical neurons.

Methods: Cortical neurons were exposed to glutamate, hydrogen peroxide (H₂O₂), or NaN₃ insult in the presence or absence of stearic acid. Cell viability of cortical neurons was determined by MTT assay and LDH release. Endogenous antioxidant enzymes activity[superoxide dismutases (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT)] and lipid peroxidation in cultured cortical neurons were evaluated using commercial kits. {3-[1(p-chloro-benzyl)-5-(isopropyl)-3-t -butylthiondol-2-yl]-2,2-dimethylpropanoic acid, Na} [MK886; 5 µmol/L; a noncompetitive inhibitor of proliferator-activated receptor (PPAR)α], bisphenol A diglycidyl ether (BADGE; 100 µmol/L; an antagonist of PPARγ), and cycloheximide (CHX; 30 µmol/L, an inhibitor of protein synthesis) were tested for their effects on the neuroprotection afforded by stearic acid. Western blotting was used to determine the PPARγ protein level in cortical neurons.

Results: Stearic acid dose-dependently protected cortical neurons against glutamate or H₂O₂ injury and increased glutamate uptake in cultured neurons. This protection was concomitant to the inhibition of lipid peroxidation and to the promotion activity of Cu/Zn SOD and CAT in cultured cortical neurons. Its neuroprotective effects were completely blocked by BADGE and CHX. After incubation with H₂O₂ for 24 h, the expression of the PPARγ protein decreased significantly (P<0.05), and the inhibitory effect of H₂O₂ on the expression of PPARγ can be attenuated by stearic acid.

Conclusion: Stearic acid can protect cortical neurons against oxidative stress by boosting the internal antioxidant enzymes. Its neuroprotective effect may be mainly mediated by the activation of PPARγ and new protein synthesis in cortical neurons.

Keywords: oxidative stress; receptors; peroxisome proliferator-activated; neurons; antioxidants