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Diamond-Stanic MK, Marchionne EM, Teachey MK, Durazo DE, Kim JS, Henriksen EJ. Jan 2011. Critical role of transient p38 MAPK activation in skeletal muscle insulin resistance caused by low-level in vitro oxidant stress. Biochem. Biophys. Res. Commun., 405:439-444
Increased cellular exposure to oxidants may contribute to the development of insulin resistance and type 2 diabetes. Skeletal muscle is the primary site of insulin-dependent glucose disposal in the body; however, the effects of oxidative stress on insulin signaling and glucose transport activity in mammalian skeletal muscle are not well understood. We therefore studied the effects of a low-level in vitro oxidant stress (30-40 ÂµM H2O2) on basal and insulin-stimulated (5 mU/ml) glucose transport activity and insulin signaling at 2, 4, and 6 hr in isolated rat soleus muscle. H2O2 increased basal glucose transport activity at 2 and 4 hr, but not at 6 hr. This low-level oxidant stress significantly impaired insulin-stimulated glucose transport activity at all time points, and was associated with inhibition of insulin-stimulated phosphorylation of Akt Ser473 and GSK-3Î² Ser9. In the presence of insulin, H2O2 decreased total protein expression of IRS-1 at 6 hr and IRS-2 at 4 and 6 hr. Phosphorylation of p38 MAPK Thr180/Tyr182 was transiently increased by H2O2 in the presence and absence of insulin at 2 and 4 hr, but not at 6 hr. Selective inhibition of p38 MAPK with A304000 partially rescued the H2O2-induced reduction in insulin-stimulated glucose transport activity. These results indicate that direct in vitro exposure of isolated mammalian skeletal muscle to a low-level oxidant stress impairs distal insulin signaling and insulin-stimulated glucose transport activity, at least in part, due to a p38 MAPK-dependent mechanism.Back