GPR40-full agonist AM1638 alleviates palmitate-induced oxidative damage in H9c2 cells via an AMPK-dependent pathway

G protein-coupled receptor 40 (GPR40) is gaining recognition as a potential therapeutic target for several metabolic disturbances, such as hyperglycemia and excessive inflammation. GPR40 is expressed in various tissues, including the heart; however, its specific roles in cardiomyocytes remain unknown. The objective of the present study was to investigate whether treatment with AM1638, a GPR40-full agonist, reduces palmitate-mediated cell damage in H9c2 rat cardiomyocytes. AM1638 treatment increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and expression levels of the antioxidant molecules heme oxygenase-1 (HO-1) and nicotinamide adenine dinucleotide phosphate: quinone oxidoreductase-1 (NQO1). Palmitate-mediated superoxide production and levels of 4-hydroxynonenal, a biomarker of oxidative stress, decreased after treatment with AM1638. Notably, palmitate-mediated disruption of mitochondrial membrane potential, lower levels of mitochondrial complex protein, and failure of adenosine triphosphate production were all recovered by treatment with AM1638. Moreover, AM1638 blocked palmitate-mediated caspase-3 cleavage and nuclear fragmentation, thereby improving cell viability. However, these AM1638-mediated beneficial effects were abrogated by treatment with Compound C, an AMPK inhibitor. These results demonstrate that AM1638, a GPR40-full agonist, ameliorates palmitate-mediated oxidative stress in H9c2 cells in an AMPK-dependent manner.