Adiponectin alleviates liver injury in sepsis rats through AMPK/MTOR pathway.

OBJECTIVE

To investigate the influences of adiponectin (APN) on the liver injury in sepsis rats and to explore whether it exerts a therapeutic effect through the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway.

MATERIALS AND METHODS

A rat model of sepsis was established through cecal ligation and puncture (CLP) (CLP group), and APN treatment group (APN group) and control group were also set. The changes in the liver function-related indicators, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were determined by automatic biochemistry analyzer, and the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1, and IL-6 were measured via enzyme-linked immunosorbent assay (ELISA). Hematoxylin-eosin (HE) staining was employed to detect liver tissue injury, and the hepatocyte apoptosis and necrosis after intervention with APN were evaluated using in situ fluorescence staining. Moreover, the mRNA expression of APN in liver tissues was detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the expression levels of phosphorylated AMPK and mTOR proteins in liver tissue samples were determined using Western blotting.

RESULTS

In terms of changes in liver function-related indicators, the concentrations of ALT and AST were substantially raised in the CLP group, and compared with those in the control group, the concentrations of the two indicators significantly declined in the APN group, showing statistically significant differences (p<0.05). CLP and APN group had evidently higher levels of inflammatory factors than the control group, but their levels in APN group were notably lower than those in the CLP group (p<0.05). It was found through the HE staining that the sepsis rats in CLP group had massive inflammatory cell infiltration, and that the inflammatory cells were remarkably decreased in the APN group after APN treatment. According to the in-situ fluorescence staining detection results, CLP group exhibited a notable increase in the cell apoptosis rate, and APN group had substantially reduced apoptotic cells (p<0.05). The determination results of APN expression revealed that CLP group had a lowered level of APN, and that the level of APN in APN group was markedly higher than that in the control group. Based on the results of Western blotting, the level of phosphorylated AMPK was remarkably elevated, and that of phosphorylated mTOR was lowered in the CLP group compared with those in the control group, while in comparison with CLP group, APN group showed a considerable elevation of phosphorylated AMPK level and a distinct decline in the phosphorylated mTOR level.

CONCLUSIONS

APN can activate the AMPK/mTOR pathway and reduce hepatocyte apoptosis to alleviate liver injury in sepsis rats.