Skeletal muscle insulin resistance after trauma: insulin signaling and glucose transport

Abstract

Surgical trauma induces peripheral insulin resistance; however, the cellular mechanism has not been fully elucidated. We examined the effects of surgical trauma on insulin receptor signaling and glucose transport in skeletal muscle, a tissue that plays a predominant role in maintaining glucose homeostasis. Surgical trauma was induced by intestinal resection in the rat. Receptor phosphorylation was not altered with surgical trauma. Phosphotyrosine-associated phosphatidylinositol (PI) 3-kinase association was increased by 60 and 82% compared with fasted and fed controls, respectively ( P < 0.05). Similar results were observed for insulin receptor substrate-1-associated PI 3-kinase activity. Insulin-stimulated protein kinase B (Akt kinase) phosphorylation was increased by 2.2-fold after surgical trauma ( P < 0.05). The hyperphosphorylation of Akt is likely to reflect amplification of PI 3-kinase after insulin stimulation. Submaximal rates of insulin-stimulated 3- O-methylglucose transport were reduced in trauma vs. fasted rats by 51 and 38% for 100 and 200 μU/ml of insulin, respectively ( P< 0.05). In conclusion, insulin resistance in skeletal muscle after surgical trauma is associated with reduced glucose transport but not with impaired insulin signaling to PI 3-kinase or its downstream target, Akt. The surgical trauma model presented in this report provides a useful tool to further elucidate the molecular mechanism(s) underlying the development of insulin resistance after surgical trauma.