Mitophagy disorder mediates cardiac deterioration induced by severe hypoglycemia in diabetic mice

Severe hypoglycemia is closely related to adverse cardiovascular outcomes in patients with diabetes; however, the specific mechanism remains unclear. We previously found that severe hypoglycemia aggravated myocardial injury and cardiac dysfunction in diabetic mice, and that the mechanism of damage was related to mitochondrial oxidative stress and dysfunction. Based on the key regulatory role of mitophagy in mitochondrial quality control, this study aimed to further explore whether the myocardial damage caused by severe hypoglycemia is related to insufficient mitophagy and to clarify their underlying regulatory relationship. After severe hypoglycemia, mitochondrial reactive oxygen species increased, mitochondrial membrane potential and ATP content decreased, and pathological mitochondrial damage was aggravated in the myocardium of diabetic mice. This was accompanied by decreased mitochondrial biosynthesis, increased fusion, and downregulated PTEN-induced kinase 1 (PINK1)/Parkin-dependent mitophagy. Treating diabetic mice with the mitophagy activator and polyphenol metabolite urolithin A activated PINK1/Parkin-dependent mitophagy, reduced myocardial oxidative stress and mitochondrial damage associated with severe hypoglycemia, improved mitochondrial function, alleviated myocardial damage, and ultimately improved cardiac function. Thus, we provide insight into the prevention and treatment of diabetic myocardial injury caused by hypoglycemia to reduce adverse cardiovascular outcomes in patients with diabetes.