Isosteviol plays a protective role on hepatic ischemia and reperfusion injury in mice through MAPK/NF-κB signaling pathway

Background: Hepatic ischemia and reperfusion (I/R) injury is of common occurrence during liver surgery and transplantation, isosteviol (ISV) is an acid hydrolysate of stevioside, the major component of Stevia rebaudiana. Stevioside and its metabolites have been shown to have varieties of pharmacological activities, However, the effect of ISV on hepatic I/R injury has not determined. The purpose of this paper is to study the effect of ISV on mice with hepatic I/R injury and further investigate its underlying mechanism. Methods: The blood vessels supplying the left/middle lobe of the liver in mice were clamped to cause liver ischemia for 1h, and then removed the clamp to conduct reperfusion for 6 h. ISV or saline was injected intraperitoneally after reperfusion. The expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6 and IL-10 in serum and tissues were evaluated by enzyme linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). The infiltration of neutrophils and macrophages into the liver tissue was determined by flow cytometry and myeloperoxidase. Liver hematoxylin-eosin (HE) staining, terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and Annexin V probe were used to determine liver injury and hepatocyte apoptosis. western blots (WB) was used to investigate the activation of nuclear factor kappa-B (NF-kappa B) and c-JunNH2 terminal kinase (JNK), p38 and extracellular regulated protein kinase (ERK), while the expression of apoptosis-related proteins B-cell lymphoma-2 (BCL-2), BCL2-associated X protein (BAX), caspase-3 was detected. Results: ISV reduced aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels to alleviate liver injury. ISV significantly reduced the release of inflammatory cytokines and the accumulation of liver neutrophils and macrophages. Meanwhile, ISV can promote the expression of anti-apoptosis-related protein BCL-2 and inhibit the expression of pro-apoptotic protein BAX and the activation of the protease caspase-3, and reduce the occurrence of hepatocyte apoptosis. Finally, ISV can reduce the phosphorylation level and activation of NF-kappa B, JNK, p38 and ERK. Conclusions: ISV inhibits the occurrence of inflammation and hepatocyte apoptosis through mitogenactivated protein kinase (MAPK)/NF-kappa B signaling pathway to relieve liver injury.