1775-P: Impact of Acetyl-CoA Carboxylase 2 Inhibition on Skeletal Muscle Diacylglycerol and Ceramide Levels and Its Potential Contribution to Improved Glucose Metabolism

Abstract

Intramyocellular lipid (IMCL) accumulation in skeletal muscle is closely associated with the development of insulin resistance. In particular, bioactive lipids such as diacylglycerol (DAG) and ceramide (Cer) have great impact on muscle insulin action. We have recently demonstrated that inhibition of acetyl-CoA carboxylase 2 (ACC2), which negatively modulates mitochondrial fatty acid oxidation in skeletal muscle, reduced IMCL levels and improved glucose metabolism in rodents. To further investigate the underlying mechanism, we examined the impact of pharmacological ACC2 inhibition on bioactive lipid composition and metabolic functions in skeletal muscle of rats, using an ACC2 selective inhibitor, compound A. As compared with vehicle treatment, chronic treatment with compound A significantly reduced both DAG and Cer levels in skeletal muscle of nondiabetic rats, which were strongly correlated with IMCL levels. Compound A also reduced the acyl-CoA pool along with enhanced acylcarnitine formation in skeletal muscle, while there were no differences in other bioactive lipid levels and DAG or Cer synthetic gene expression levels. Similarly, in Zucker diabetic fatty (ZDF) rats, compound A reduced both DAG and Cer levels in skeletal muscle without suppressing the synthetic gene expression levels. Treatment with compound A led to improved hyperinsulinemia and upregulated expression of key regulators in energy metabolism, such as Glut4 and Pgc1α, in skeletal muscle. Moreover, these positive effects on glucose metabolism were strongly correlated with diacylglycerol and ceramide reductions. Collectively, these findings suggest that ACC2 inhibition leads to preferential reductions of DAG and Cer by directly decreasing acyl-CoA pool via fatty acid oxidation in skeletal muscle, and these lipid reductions are closely linked to the improvement of glucose metabolism by ACC2 inhibition. Disclosure H. Takagi: None. T. Ikehara: None. K. Hashimoto: None. A. Shimazaki: None. Y. Kashiwagi: None. Y. Nishiura: None. M. Notoya: None. H. Yukioka: None.