Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is hyperactive in liver, adipose and skeletal muscle tissues of obese rodents. Alpha-lipoic acid (αLA) has been well accepted as a weight-loss treatment, though there are limited studies on its effect on mTOR signaling in high-fat fed, obese rodents. Therefore, the goal of this study was to determine mTOR signaling and oxidative protein alterations in skeletal muscle of high-fat fed, obese rats after αLA supplementation. Phosphorylation of the mTOR substrate, eukaryotic initiation factor (eIF) 4E-binding protein 1 (4E-BP1) and eIF4B were significantly reduced (p < 0.05) in muscle from αLA supplemented rats. Activation of AMP-activated protein kinase (AMPK), an mTOR inhibitory kinase, was higher (p < 0.05) in the αLA group. Protein expression of markers of oxidative metabolism, acetyl CoA carboxylase (ACC), cytochrome c oxidase IV (COX IV), peroxisome proliferator-activated receptor (PPAR), and PPAR gamma coactivator 1-alpha (PGC-1α) were significantly higher (p < 0.05) after αLA supplementation compared to non-supplemented group. Our findings show that αLA supplementation limits the negative ramifications of consuming a high fat diet on skeletal muscle markers of oxidative metabolism and mTORC1 signaling.