Sepsis-associated myocardial injury is one of the main causes of death in intensive care units, and current clinical treatments have not been satisfactory. Therefore, finding an effective intervention is an urgent requirement.
Metformin, an anti-
type 2 diabetes drug, has been reported to be an autophagic activator agent that confers protection in some diseases. However, it is unclear whether it can provide defense against
sepsis-associated myocardial injury. In this study, we investigated the cardioprotective effects of
metformin pretreatment against
lipopolysaccharide (LPS)-induced myocardial injury in C57BL/6J mice or H9c2 cells and the possible underlying mechanisms.
Metformin was administered at a dose of 100 mg/kg for a week before LPS
intraperitoneal injection. Twenty-four hours after LPS intervention, echocardiographic evaluation,
reactive oxygen species measurement, Hoechst staining, western blotting,
hematoxylin and
eosin staining, and
enzyme-linked
immunosorbent assay were performed. Inhibitors of autophagy and
AMP-activated protein kinase (AMPK) were used to further clarify the mechanisms involved.
Metformin pretreatment effectively attenuated cardiac dysfunction, reduced the levels of myocardial
enzymes, and alleviated cardiac hydroncus in LPS-treated mice. In addition,
metformin restored the LPS-disrupted
antioxidant defense and activated LPS-reduced autophagy by modulating the AMPK/
mammalian target of rapamycin (AMPK/mTOR) pathway both in vivo and in vitro. The
antioxidant effects of
metformin on cardiomyocytes were abolished by the autophagy inhibitor
3-methyladenine (3-MA). Treatment with compound C, an AMPK inhibitor, reversed the
metformin-induced autophagy in LPS-treated H9c2 cells. In conclusion,
metformin pretreatment alleviates LPS-induced myocardial injury by activating AMPK/mTOR pathway-mediated autophagy.