AMPK dependent protective effects of metformin on tumor necrosis factor-induced apoptotic liver injury

Tumor necrosis factor α (TNF-α)-induced cellular apoptosis represents a common pathological mechanism underlying the progression of various liver disorders. Recently studies revealed that the anti-diabetic metformin provided protective benefits in several animal models of liver injury. In the present study, the potential modulatory effects of metformin on TNF-α-dependent apoptotic liver damage was investigated in mice with TNF-α/d-galactosamine (D-Gal)-induced liver injury. The results indicated that treatment with metformin significantly suppressed the elevation of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the activation of caspase cascade and the induction of cleaved caspase-3. Morphological analysis showed that metformin alleviated histopathological abnormalities and reduced TUNEL-positive apoptotic cells. Co-administration of the AMPK inhibitor compound C completely abolished the inhibitory effects of metformin on caspase cascade activation, significantly reversed the beneficial effects of metformin on histopathological abnormalities and hepatocytes apoptosis, and partially abolished the suppressive effects of metformin on plasma ALT elevation. These data indicated that metformin effectively alleviated TNF-α/D-Gal-induced apoptotic liver injury and these beneficial effects were at least partially mediated by AMPK.