The protective mechanism of magnolol,a Chinese herb drug,against warm ischemia-reperfusion injury of rat liver

BACKGROUND: Cell apoptosis following warm ischemia-reperfusion injury is a major concern in clinical issues such as organ transplantation, trauma, and cardiogenic shock. The purpose of this study was to evaluate the possible role of magnolol, a Chinese herb drug, in apoptotic injury and the kinetic expression of apoptotic-related genes in rat livers subjected to warm ischemia-reperfusion (WI/R). MATERIALS AND METHODS: Three weeks prior to the experiment 10 rats underwent a portosystemic shunt operation according to Bengmerk's method. The rats were divided into three groups. Group 1 (GI) was the control group, Group 2 (GII) and Group 3 (GIII) the magnolol-treated groups. GI and GII were subjected to 2 h and GIII to 3 h of WI/R by clamping the portal vein and hepatic artery under ether anesthesia. RESULTS: Results show that all the control rats died after 2 h WI/R. Apoptotic cells were detected under microscopy as well as by DNA assay. Magnolol-treated groups tolerated warm ischemia-reperfusion for 2 h and significantly less apoptotic cells were observed (198 +/- 22 vs 42.6 +/- 28). But magnolol-treated rats could not tolerate 3 h warm ischemia-reperfusion. RT-PCR of liver tissue shows that there is an upregulated expression of the anti-apoptotic Bcl-xL gene and suppression of the Bcl-xS gene in GII. CONCLUSION: Magnolol has an anti-apoptotic effect and protects the liver against WI/R for 2 h but not for 3 h through upregulation of the anti-apoptotic Bcl-XL gene and suppression of the Bcl-xS gene.