[Shihu Mixture alleviates diabetic cardiomyopathy in rats by Sirt3-mediated upregulation of myocardial mitochondrial mitophagy pathway].

OBJECTIVES

To explore the mechanism of Shihu Mixture (SHM) for improving diabetic cardiomyopathy.

METHODS

Thirty male SD rats were randomized into 3 groups (n=10) for type 2 diabetes mellitus modeling by high-fat and -sugar feeding for 12 weeks and intraperitoneal streptozotocin injection, followed by treatment with daily gavage of normal saline (model group), metformin solution, or SHM extract for 4 weeks, with 10 normally fed rats as the normal control group. Fasting blood glucose and cardiac weight index of the rats were monitored, and their TG, TC, LDL-C, HDL-C, and LDH levels were determined; serum and myocardial levels of BNP, CRP, TNF‑α and IL-6 were detected with ELISA. Myocardial pathological changes and ultrastructures of myocardial mitochondria and autophagosomes were examined with HE and Masson staining and transmission electron microscopy. Myocardial expressions of Sirt3, FoxO3a, PINK1, Parkin, P62, and LC3 mRNAs and proteins were detected with RT-qPCR, Western blotting, and immunohistochemistry.

RESULTS

Compared with those in the control group, the rats in the other 3 groups showed significantly increased fasting blood glucose, cardiac weight index, serum TC, TG, LDL-C, LDH, CRP and BNP levels and myocardial levels of TNF‑α and IL-6 with lowered HDL-C level, obvious myocardial and mitochondrial pathologies, and dysregulated expression of Sirt3, FoxO3a, p-FoxO3a, PINK1, Parkin, LC3 and P62. Treatment of the rat models with SHM extract significantly reduced fasting blood glucose level and cardiac weight index, lowered the levels of LDH, CRP, BNP, TNF‑α, IL-6, TC, TG, and LDL-C, increased HDL-C level, alleviated myocardial and mitochondrial damages, promoted autophagosome formation, and improved dysregulation of mitochondrial autophagy-related gene expression, showing similar effects to metformin.

CONCLUSIONS

SHM alleviates myocardial damage and improves mitochondrial function in rats with diabetic cardiomyopathy by regulating the mitochondrial autophagy pathway through Sirt3.