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

doi:10.12122/j.issn.1673-4254.2026.01.05

Abstract

Abstract:

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

Key words: diabetic cardiomyopathy, Shihu Mixture, mitophagy, Sirt3 pathway

Xinjun LIN, Yulin HE, Hong SHI, Jiaxiu LIU, Haixia HU. Shihu Mixture alleviates diabetic cardiomyopathy in rats by Sirt3-mediated upregulation of myocardial mitochondrial mitophagy pathway[J]. Journal of Southern Medical University, 2026, 46(1): 47-54.

Figures/Tables 7

Fig.1 Changes in fasting blood glucose and cardiac weight index of the rats. n=3,**P<0.01 vs NC group; #P<0.05, ##P<0.01 vs DCM group. NC: Normal control group; DCM: Model group; MET: Metformin-treated group; SHM : Shihu mixture-treated group.

Fig.2 Effect of Shihu mixture (SHM) on blood lipid levels in the rat models. n=3, **P<0.01 vs NC group; ##P<0.01 vs DCM group.

Tab.1 Contents of LDH， CRP and BNP in rat serum and TNF-α， IL-6 in rat myocardium （n=3）

Group	LDH (mmol/L)	CRP (ng/mL)	BNP (pg/mL)	TNF-α (pg/mL)	IL-6 (pg/mL)
NC	1388.6±105.4	1.40±0.01	72.67±4.92	30.28±4.25	18.72±5.42
DCM	2002.9±112.2**	2.98±0.08**	173.89±4.24**	156.36±16.62**	64.62±8.51**
MET	1659.0±73.1^##	2.47±0.06^##	137.77±4.69^##	62.82±9.35^##	22.12±6.23^##
SHM	1613.6±83.3^##	2.25±0.08^##	128.84±7.48^##	83.17±8.02^##	34.08±5.83^##

Fig.3 HE and Masson staining of rat myocardial tissue. A: HE staining. B: Masson staining.

Fig.4 Ultrastructural changes of mitochondria (A) and autophagosomes (B) in rat myocardial tissue.

Fig.5 Expressions of cardiac mitophagic pathway and autophagy-related genes in rats. A: Expresisons of cardiac mitophagic pathway-related genes. B: Expressions of autophagy-related genes.n=3, *P<0.05, **P<0.01 vs NC group; ##P<0.01 vs DCM group.

Fig.6 Expression of cardiac mitophagic pathway and autophagy-related proteins in rats. A: Representative immunoblot images. B: Sirt3, p-FoxO3a/FoxO3a, PINK1, Parkin relative protein expression levels. C: Representative immunohistochemical images. D: LC3 and P62 relative protein expression levels. n=3, *P<0.05, **P<0.01 vs NC group; #P<0.05, ##P<0.01 vs DCM group.

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