Cinnamon Polyphenols Ameliorate the Dysregulation of Cardiac Energy and Autophagic Homeostasis in Rats with Diabetic Cardiomyopathy via the mTOR/PGC1α Pathway

Background Inflammation mediated by hyperglycemia, lipid metabolism disorders, abnormal myocardial energy metabolism, myocardial cell damage, and changes in ventricular structure are important mechanisms in the occurrence and development of diabetic cardiomyopathy (DCM). Cinnamon polyphenols (CP) are extracted from the traditional Chinese medicine cinnamon, which is believed to have cardioprotective effects and has been used in China for hundreds of years. Objectives This study aimed to investigate the therapeutic effects of CP on DCM and its possible mechanisms. Materials and Methods The DCM model was established by a single intraperitoneal injection of 85 mg/kg 1% streptozotocin in rats. The treatment group was orally administered 135 mg/kg CP for 28 consecutive days, a dosage verified by experiments on AC16 myocardial cells and detecting liver and kidney injury markers. Results CP could reduce high blood sugar, high blood lipids, left ventricular mass index, levels of myocardial injury markers, adenosine diphosphate (ADP), and cyclic adenosine monophosphate (cAMP) in the model group. It also improved weight loss, and increased myocardial adenosine triphosphate (ATP), adenosine monophosphate (AMP), phosphocreatine (PCr), and ATP/ADP, AMP/ATP, and PCr/ATP ratios. The expression of p-mTOR/mammalian target of rapamycin (mTOR), p62, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) in the myocardium of the CP group was enhanced, while the expression of LC3II/LC3I was inhibited. Conclusion CPs can alleviate myocardial damage by reducing blood sugar, blood lipids, and abnormal autophagy levels while promoting the restoration of myocardial energy metabolism homeostasis.