Anti-inflammative effect of glycyrrhizin on rat thermal injury via inhibition of high-mobility group box 1 protein.

Abstract Aim Glycyrrhizin (Gly) has been reported as an inhibitor of extracellular HMGB1 (high-mobility group box 1 protein) 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 (200–250 g) 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 to 30% TBSA (Total Body Surface Area) full-thickness scald injury. In Gly-treated burn group, glycyrrhizin (60 mg/kg) was administered intraperitoneally immediately after and at 24th hour burn; in vehicle-treated burn group, Ringer's solution (4 ml/kg, as a vehicle) was administered intraperitoneally immediately after and at 24th hour burn. The animals were sacrificed at 48 h after injury. Aortic blood samples were obtained to detect tumor necrosis factor-α (TNF-α) 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 HMGB1 mRNA and protein. HMGB1 mRNA level was semiquantitatively measured by Real-Time PCR using β-actin as an internal standard, and protein expression of HMGBI was determined by Western blot. Results Severe skin scald injury caused a significant increase in plasma TNF-α and IL-1β versus the control group ( P P P P Conclusion These results demonstrate that Gly possesses an anti-inflammation effect to protect the remote organs from burn-induced injury.