Leptin relieves intestinal ischemia/reperfusion injury by promoting ERK1/2 phosphorylation and the NO signaling pathway

BACKGROUND: Recently, research has indicated that leptin plays a protective role in traumatic brain and liver injury. We studied the protective effect of leptin on intestinal I/R injury and examined its mechanism by using mice intestinal I/R model and murine peritoneal macrophage hypoxia/reoxygenation (H/R) injury model. METHODS: Leptin was intraperitoneally administrated at 45 minutes after ischemia, then reperfusion for two hours. Cells were treated with different concentrations of leptin at three hours after hypoxia, then reoxygenation for six hours. Mice intestines were harvested for histopathologic properties. The malondialdehyde, nitric oxide (NO), interleukin-6, and total antioxidative capacity were detected according to respective assay kit. Phosphorylated extracellular regulated kinase1/2 (p-ERK1/2) and phosphorylated cytosolic phospholipase A(2) (p-cPLA(2)) were determined by Western blot assay. RESULTS: Here, we show that leptin reduced intestinal histologic alterations, malondialdehyde and interleukin-6 levels but increased the endogenous leptin expression and NO production in the intestines. Leptin also increased the NO and total antioxidative capacity levels in cells. We further demonstrated that leptin markedly activated ERK1/2 in the intestines and activated ERK1/2 and cPLA(2) in the cells. Moreover, the protective effect of leptin against intestinal I/R injury and elevated NO production was attenuated by blocking the ERK1/2 pathway. CONCLUSIONS: These data demonstrate that leptin ameliorated intestinal I/R and peritoneal macrophage H/R injury by enhancing ERK1/2 phosphorylation and promoting the NO production signaling pathway. (J Trauma. 2012;72: 143-149. Copyright (C) 2012 by Lippincott Williams & Wilkins)