Anti-inflammative Effect Of Glycyrrhizin On Rat Thermal Injury Via Inhibition Of High-Mobility Group Box1Protein

Aim:Glycyrrhizin (Gly) has been reported as a inhibitor of extracellular HMGB1(High-Mobility Group Box1Protein)cytokine’s activity, and protects spinal cord, liver, heart and brain against ischemia-reperfusion-induced injury in rats. The purpose of this study was to investigate the protective effect of Gly in rat skin thermal injury model and to elucidate the underlying mechanisms.Methods:Twenty-four male Sprague-Dawley rats(200-250g) were randomly divided into control group, vehicle-treated and Gly-treated burn groups, each group contained eight animals. In the latter two groups, rats were subjected to30%TBSA (Total Body Surface Area) full-thickness scald injury, and then4ml/kg Ringer’s solution or Gly (60mg/kg) was administered intraperitoneally after and at24hour burn, respectively. The animals were sacrificed at48h after injury. Aortic blood samples were obtained to detect tumor necrosis factor-a (TNF-a) and interleukin-1β(IL-1β) with ELISA(Enzyme-Linked Immuno Sorbent Assay) kits. Lung, liver and kidney tissue samples were collected to determine the expression of HMGB1mRNA and protein. HMGB1mRNA level was semiquantitatively measured by Real-Time PCR using β-actin as an internal standard, and protein expression of HMGB1was determined by Western blot.Results:Severe skin scald injury caused a significant increase in plasma TNF-a and IL-1β versus the control group(P<0.001) in48hours after burns. Intraperitoneal administration of Gly (60mg/kg) significantly reduced the levels of serum TNF-a and IL-1β(P<0.01). Gly treatment reduced these biochemical indices accompanied by lower level of HMGB1protein(P<0.05) and mRNA expression(P<0.01).Conclusion:These results demonstrate that Gly possesses an anti-inflammation effect to protect the remote organs from burn-induced injury.