Astragaloside IV prevents calpain-1-mediated cardiac hypertrophy and fibrosis induced by diabetes.

OBJECTIVE

Astragaloside IV (AsIV) has been reported to alleviate diabetes-induced endothelial dysfunction by inhibiting calpain-1. This study aimed to determine whether the same mechanism underlies its protective effect against diabetic cardiomyopathy (DCM).

METHODS

At the in vivo level, calpain-1 knockout mice with the genotype Capn1 EK684-/- (Capn1 EK684 knockout mice) were used to establish a type 2 diabetic cardiomyopathy model. At the in vitro level, H9c2 cells and cardiac fibroblasts were stimulated with high glucose to construct corresponding models. Meanwhile, a calpain-1 overexpression lentivirus was constructed to assess the effect of calpain-1 on myocardial cell injury. Different doses of AsIV were then used to intervene in diabetic mice and H9c2 cells. Body weight, blood glucose, myocardial hypertrophy, myocardial fibrosis, cardiac function, Ca2+ overload and its regulation, myocardial cell apoptosis and oxidative stress were evaluated in the current study.

RESULTS

AsIV could not completely normalize blood glucose in mice, but could significantly improve cardiac systolic and diastolic function, myocardial hypertrophy and fibrosis. The beneficial effect of calpain-1 gene knockout on diabetic cardiomyopathy was similar to that of AsIV, and calpain-1 knockout did not further enhance the beneficial effect of AsIV. Calpain-1 overexpression abolished the beneficial effect of AsIV on high glucose induced H9c2 cell injury and fibroblast proliferation. In addition, the intracellular Ca2+ overload, abnormal levels of sarco/endoplasmic reticulum Ca2+-ATPase 2a (SERCA2a), phosphorylation of phospholamban (p-PLN) and ryanodine receptor 2 (p-RyR2), apoptosis and oxidative stress associated with DCM were also improved by AsIV or calpain-1 knockout, and AsIV has the capacity to suppress the overactivation of calpain-1 and calcium/calmodulin-dependent protein kinase Ⅱ (CaMKII).

CONCLUSIONS

AsIV could ameliorate intracellular Ca2+ overload, apoptosis, and oxidative stress by regulating the calpain-1/CaMKII pathway, thereby improving myocardial hypertrophy and fibrosis caused by diabetes mellitus.