The Stimulatory Effect of Essential Fatty Acids on Glucose Uptake Involves Both Akt and AMPK Activation in C2C12 Skeletal Muscle Cells

Abstract

Essential fatty acid (EFA) is known to be required for the body to function normally and healthily. However, the effect of EFA on glucose uptake in skeletal muscle has not yet been fully investigated. In this study, we examined the effect of two EFAs, linoleic acid (LA) and α-linolenic acid (ALA), on glucose uptake of C2C12 skeletal muscle cells and investigated the mechanism underlying the stimulatory effect of polyunsaturated EFAs in comparison with monounsaturated oleic acid (OA). In palmitic acid (PA)-induced insulin resistant cells, the co-treatment of EFAs and OA with PA almost restored the PA-induced decrease in the basal and insulin-stimulated 2-NBDG (fluorescent D-glucose analogue) uptake, respectively. Two EFAs and OA significantly protected PA-induced suppression of insulin signaling, respectively, which was confirmed by the increased levels of Akt phosphorylation and serine/threonine kinases (PKCθ and JNK) dephosphorylation in the western blot analysis. In PA-untreated, control cells, the treatment of 500 µM EFA significantly stimulated 2-NBDG uptake, whereas OA did not. Phosphorylation of AMP-activated protein kinase (AMPK) and one of its downstream molecules, acetyl-CoA carboxylase (ACC) was markedly induced by EFA, but not OA. In addition, EFA-stimulated 2-NBDG uptake was significantly inhibited by the pre-treatment of a specific AMPK inhibitor, adenine 9-β-D-arabinofuranoside (araA). These data suggest that the restoration of suppressed insulin signaling at PA-induced insulin resistant condition and AMPK activation are involved at least in the stimulatory effect of EFA on glucose uptake in C2C12 skeletal muscle cells.

Cessation of biomechanical stretch model of C2C12 cells models myocyte atrophy and anaplerotic changes in metabolism using non-targeted metabolomics analysis

“…Specifically, palmitic acid, alpha-Monopalmitin, and/or Beta-Monopalmitin were found at each time found (Supplemental Table 1). Recent studies have demonstrated that the essential fatty acids linoleic acid (LA) and alpha-linolenic acid (ALA) themselves can improve glucose uptake in C2C12 cells made insulin resistant using palmitic acid 39 , making the balance between fatty acids and glucose critically important when modeling myocytes in vitro.…”

Effects of Icariin on insulin resistance via the activation of AMPK pathway in C2C12 mouse muscle cells

“…Also, a positive control, metformin did not show any cytotoxicity up to 1 mM on C2C12 cells (data not shown). In previous reports, metformin at concentration of 1 mM has no toxicity and commonly used on C2C12 cells (Bruckbauer and Zemel, 2013;Park et al, 2014). Therefore, we used metformin at concentration of 1 mM and icariin at concentrations of 100 μM or less for subsequent studies.…”

Lipid modulation of skeletal muscle mass and function

“…In contrast, an independent study by Tardif and co‐workers demonstrated that aged rats fed an oleate‐enriched diet display marked improvements in insulin sensitivity as well as increased muscle protein synthesis, concomitant with increased expression of genes implicated in stimulating mitochondrial β‐oxidation including peroxisome proliferator‐activated receptor (PPAR)α and PPARβ, as well as CPT‐1β . Moreover, C2C12 myotubes treated with the PUFAs linolenic acid and ALA have been shown to exhibit increased activation of AMPK, another key positive regulator of mitochondrial β‐oxidation . In addition, DHA has also been reported to inhibit protein degradation in C2C12 myotubes through a PPARγ‐dependent pathway .…”