| Background Ischemia-reperfusion (ischemia reperfusion, I/R) injury is the phenomenon that the organ in the basis of ischemia after the reperfusion, tissues and organs instead of aggravating the injury. The extract of licorice, which has anti-inflammatory, anti-allergic, the protection of membrane structure and role in immune regulation, and has protective effect in heart and kidney after ischemia reperfusion injury, as well as studies show that the licorice derivatives can reduce the injury caused by acute ischemic in skeletal muscle and hippocampus after reperfusion. The initial pathological change in the reperfusion injury was thought to be damage to the vascular endothelium resulting from increased permeability of capillary vessles due to prolonged ischemia in the tissue. Victorino, etc.considered that the result of ischemia-reperfusion injury may be due to enhanced the adhesion of leukocyte and endothelial cells caused by the increased expression of intercellular adhesion molecule. P-selectin molecules on the luminal surface of endothelial cells are responsible for interaction with PMNs through the glycoprotein counterreceptors expressing sialyl-Lewis X, which is located on the surface of PMNs and adhere firmly to the PMNs. Then the PMNs subsequently migrate out of the microcirculation. The activated PMNs also increase the permeability of the vascular endothelium by the release of free radicals generated from neutrophil myeloperoxidase and necrosis of ischemia tissue[11-12]. Glycyrrhizin, an agent with a chemical structure analogous to that of sialyl-Lewis X and the ability to bind P-selectins was used to compete with the sialyl-Lewis X oligosaccharides on neutrophils and to block neutrophils adhesion to the vascular endothelium. Given this, interference to the p-selectin and PMNs interaction might prevent or ameliorate the pathological reactions involved in ischemia reperfusion injury.Objective To observe the effect of glycyrrhizin on ischemia/reperfusion injury in skeletal muscle(SMIRI)of rabbits.Methods Twenty-four rabbits were randomly divided into three groups. These animals were used for making the models of ischemia/reperfusion of the right hind limb.The shame group was not asked for ischemia damage, and only isolated the femoral artery. The other two groups were asked for ischemia damage 4 hour's,solutions of glycyhrrizin 2ml/kg(10mg/m1)were infused into ear source vein of the group of glycyrrhizin rabbits.The other two group rabbits were infused with equal amount of physical saline. after the model was set up, the effect of glycyrrhizin on plasma lactate dehydrogenase (LDH), creatine kinase (CK) was detected with automatic biochemical analyzer, the malondialdehyde (MDA) was detected with thiobarbituric acid method (TBA), according to the kit, the change of myeloperoxidase (MPO) was detected, used RT-PCR determining of P-selectin (P-selectin, Ps) mRNA change, and by weighing method detected the wet weight/dry weight values (W/D), the histopathological changes in skeletal muscle under a light microscope was observed, by t-test and variance analysis comparing of the differences in each group.Results The plasma contents of CK, LDH, MDA and the MPO, W/D of skeletal muscle in control group (393.95±46.64,17.47±0.85, 9.43±0.43, 3.93±0.51, 5.63±0.61), and glycyrrhizin group (158.28±60.89, 13.08±0.84, 6.78±0.53, 2.14±0.24, 4.77±0.46) were significantly higher than that in shame group(5.38±0.98, 5.96±0.88, 89.94±60.08, 1.13±0.23, 4.06±0.13), values of F were 105.32, 5.06, 69.16, 128.20, 24.60, values of P were all less than 0.001.The expression of Ps mRNA in control group (0.87±0.04)were significantly higher than those in glycyrrhizin group and sham group(0.76±0.06, 0.70±0.08), F =16.64, P<0.05. The necrosis muscle fibers in control group(247.97±145.43) were heavier than that in glycyrrhizin group(90.85±40.02),t = 2.89, P<0.05.Conclusion Glycyrrhizin have a better protection in skeletal muscle from SMIRI.
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