The Critical Role of Astragalus Polysaccharides for the Improvement of PPRAα-Mediated Lipotoxicity in Diabetic Cardiomyopathy

Background: Obesity-related diabetes mellitus leads to increased myocardial uptake and oxidation of fatty acids, resulting in a form of cardiac dysfunction referred to as lipotoxic cardiomyopathy. We have shown previously that Astragalus polysaccharides (APS) administration was sufficient to improve the systemic metabolic disorder and cardiac dysfunction in diabetic models. Methodology/Principal Findings: To investigate the precise role of APS therapy in the pathogenesis of myocardial lipotoxity in diabetes, db/db diabetic mice and myosin heavy chain (MHC)- peroxisome proliferator-activated receptor (PPAR) alpha mice were characterized and administrated with or without APS with C57 wide- type mice as normal control. APS treatment strikingly improved the myocyte triacylglyceride accumulation and cardiac dysfunction in both db/db mice and MHC-PPAR alpha mice, with the normalization of energy metabolic derangements in both db/db diabetic hearts and MHC-PPAR alpha hearts. Consistently, the activation of PPAR alpha target genes involved in myocardial fatty acid uptake and oxidation in both db/db diabetic hearts and MHC-PPAR alpha hearts was reciprocally repressed by APS administration, while PPAR alpha-mediated suppression of genes involved in glucose utilization of both diabetic hearts and MHC-PPAR alpha hearts was reversed by treatment with APS. Conclusions: We conclude that APS therapy could prevent the development of diabetic cardiomyopathy through a mechanism mainly dependent on the cardiac PPAR alpha-mediated regulatory pathways.