Abstract
AMP-activated protein kinase (AMPK), an enzyme that plays a role in cellular energy homeostasis, modulates myocardial signaling in the heart. Myocardial dysfunction is a common complication of sepsis. Autophagy is involved in the aging related cardiac dysfunction. However, the role of AMPK in sepsis-induced cardiotoxicity has yet to be clarified, especially in aging. In this study, we explored the role of AMPK in lipopolysaccharide (LPS)-induced myocardial dysfunction and elucidated the potential mechanisms of AMPK/mTOR pathway regulating autophagy in young and aged mice. We harvested cardiac tissues by intraperitoneal injection of LPS treatment. The results by echocardiography, pathology, contractile and intracellular Ca2+ property as well as western blot analysis revealed that LPS induced remarkable cardiac dysfunction and cardiotoxicity in mice hearts and cardiomyocytes, which were more seriously in the aged mice. Western blot analysis indicated that the underlying mechanisms included inhibition autophagy mediated by AMPK/mTOR activation. LPS overtly promoted the expression of AMPK upstream regulator PP2A and PP2Cα. Pharmacological activation of AMPK improved cardiac function and upregulated cardiac autophagy induced by LPS in the aged mice. Collectively, our findings suggest that upregulation of autophagy by administration of AMPK could attenuate LPS-induced cardiotoxicity, which enhances our knowledge to explore new drugs and strategies for combating cardiac dysfunction induced by sepsis.