Involvement of PI3K/PKG/ERK1/2 signaling pathways in cortical neurons to trigger protection by co-treatment of acetyl-L-carnitine and α-lipoic acid against HNE-mediated oxidative stress and neurotoxicity: Implications for Alzheimers disease.

摘要

Oxidative stress has been shown to underlie neuropathological aspects of Alzheimer's disease (AD). 4-Hydroxy-2-nonenal (HNE) is a highly reactive product of lipid peroxidation of unsaturated lipids. HNE-induced oxidative toxicity is a well-described model of oxidative stress-induced neurodegeneration. GSH plays a key role in antioxidant defense, and HNE exposure causes an initial depletion of GSH that leads to gradual toxic accumulation of reactive oxygen species. In the current study, we investigated whether pre-treatment of cortical neurons with acetyl-L-carnitine (ALCAR) and α-lipoic acid (LA) plays a protective role in cortical neuronal cells against HNE-mediated oxidative stress and neurotoxicity. Decreased cell survival of neurons treated with HNE correlated with increased protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (HNE) accumulation. Pretreatment of primary cortical neuronal cultures with ALCAR and LA significantly attenuated HNE-induced cytotoxicity, protein oxidation, lipid peroxidation and apoptosis in a dose-dependent manner. Additionally, pretreatment of ALCAR and LA also led to elevated cellular GSH and heat shock proteins (HSPs) levels compared to untreated control cells. We have also determined that pretreatment of neurons with ALCAR and LA leads to the activation of phosphoinositol-3 kinase (PI3K), PKG and ERK1/2 pathways, which play essential roles in neuronal cell survival. Thus, this study demonstrates a cross talk between the PI3K, PKG and ERK1/2 pathways in cortical neuronal cultures that contributes to ALCAR and LA-mediated pro-survival signaling mechanisms. This evidence supports the pharmacological potential of co-treatment of ALCAR and LA in the management of neurodegenerative disorders associated with HNE-induced oxidative stress and neurotoxicity, including AD.