Alpha-lipoic acid supplementation increases markers of lipid oxidation and reduces mTOR signaling in skeletal muscle of high-fat fed Zucker rats
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Alpha-lipoic acid (αLA) has well established metabolic benefits as a nutraceutical, however, there are limited studies on its metabolic benefits in relation to growth regulatory pathways. Therefore, the goal of this study was to determine the role of αLA supplementation on markers of lipid oxidation and the mammalian target of rapamycin (mTOR) growth signaling in skeletal muscle of high-fat fed Zucker rats. Protein expression of markers for lipid uptake, carnitine palmitoyltransferase I (CPT1), mitochondria capacity, cytochrome c oxidase IV (COX IV), transcriptional regulators of oxidative process, peroxisome proliferator-activated receptor-alpha (PPAR-α), PPAR gamma coactivator 1-alpha (PGC-1α) significantly increased in skeletal muscle of αLA supplemented high fat fed rat compared to the high fat fed, non-supplemented group. Meanwhile, the mTOR substrate eukaryotic translation initiation factor 4E-binding protein 1(4E-BP1) phosphorylation significantly decreased in αLA-supplemented group. αLA supplementation also reduced Akt protein activation. These findings suggest that αLA supplementation limits the negative effects of a high-fat diet on markers of skeletal muscle lipid oxidation and growth pathway activation through mTOR.