Mogroside IIe Ameliorates Cardiomyopathy by Suppressing Cardiomyocyte Apoptosis in a Type 2 Diabetic Model

Abstract

Mogroside II_e is primarily present in the unripe fruit of Siraitia grosvenorii (Swingle) C. Jeffrey, and it is the predominant saponin component. The purpose of this study was to investigate the effects of mogroside IIe (MGE IIe) on myocardial cell apoptosis in diabetic cardiomyopathy (DCM) rats by establishing a high-sugar and high-fat diet-induced model of type 2 diabetes (T2D) in SD rats and a homocysteine (Hcy)-induced apoptotic model in rat H9c2 cardiomyocytes. The results showed that MGE IIe decreased the levels of fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) levels, but increased the levels of high-density lipoprotein (HDL) in the SD rat model. Furthermore, MGE IIe decreased the levels of lactate dehydrogenase 2 (LDH2), creatine phosphokinase isoenzyme (CKMB), and creatine kinase (CK), and improved heart function. Additionally, MGE IIe inhibited the secretion of interleukin-1 (IL-1), IL-6, and tumor necrosis factor-α (TNF-α), improved myocardial morphology, and reduced myocardial apoptosis in the SD rat model. Furthermore, MGE IIe inhibited the mRNA and protein expression of active-caspase-3, -8, -9, -12, and Bax and Cyt-C, and promoted the mRNA and protein expression of Bcl-2 in the SD rat model. Furthermore, MGE IIe suppressed homocysteine-induced apoptosis of H9c2 cells by inhibiting the activity of caspases-3, -8, -9, and -12. In conclusion, MGE IIe inhibits the apoptotic pathway, thereby relieving DCM in vivo and in vitro.

Keywords: H9c2 cells; MGE II; SD rats; apoptosis; type 2 diabetic cardiomyopathy.

FIGURE 1

MGE IIe slows down the damage to cardiomyocytes in the DCM model. (A) The structural formula of MGE IIe. (B) MGE IIe decreased the serum glucose concentration. (C) MGE IIe inhibited lipid accumulation. (D) MGE IIe decreased the ratio of heart to body weight. (E) MGE IIe improved cardiac function. (F) MGE IIe inhibited the secretion of inflammatory cytokines. (G) MGE IIe improved cardiomyocyte damage as revealed by HE staining. (H) MGE IIe reduced cardiomyocyte apoptosis as revealed by TUNEL staining assay. Bar = 50 µm. One-way ANOVA was followed by post hoc tests for comparisons among groups. The values shown represent the mean ± standard error of the mean (SEM) of the data from three independent experiments. ^# p < 0.05 (compared to the control group alone); ^* p < 0.05 (compared to the model group alone).

FIGURE 2

MGE IIe inhibits the expression of apoptotic factors of the caspase family. (A) MGE IIe inhibited mRNA expression of caspase-3, -8, -9, and -12 as assessed by qPCR assay. (B) MGE IIe suppressed the activity of caspase-3, -8, -9, and -12 as revealed by western blot assay. (C) MGE IIe suppressed the activity of caspase-3, -8, -9, and -12 as revealed by IHC assay. Bar = 50 µm. One-way ANOVA was followed by post hoc tests for comparisons among groups. The values shown represent the mean ± standard error of the mean (SEM) of the data from three independent experiments. ^# p < 0.05 (compared to the control group alone); ^* p < 0.05 (compared to the model group alone).

FIGURE 3

MGE IIe inhibits the expression of apoptotic factors Bax and Cyt-C and promotes the expression of Bcl-2. (A) MGE IIe inhibited the mRNA expression of Bax and Cyt-C, and promoted the mRNA expression of Bcl-2 as revealed by qPCR assay. (B) MGE IIe suppressed the protein expression of Bax and Cyt-C and promoted the protein expression of Bcl-2 as revealed by western blot assay. (C) MGE IIe suppressed the protein expression of Bax and Cyt-C and promoted the protein expression of Bcl-2 as revealed by IHC assay. Bar = 50 µm. One-way ANOVA was followed by post hoc tests for comparisons among groups. The values shown represent the mean ± standard error of the mean (SEM) of the data from three independent experiments. ^# p < 0.05 (compared to the control group alone); ^* p < 0.05 (compared to the model group alone).

FIGURE 4

MGE IIe inhibits the apoptosis of H9c2 cells induced by Hcy. (A) The effect of Hcy on H9c2 cell viability. (B) The effect of MGE IIe on the H9c2 cell viability. (C) The effect of MGE IIe on the Hcy-induced H9c2 cells apoptosis model by flow cytometry. (D) The effect of Hcy on the activity of caspase-3, -8, -9, and -12 in H9c2 cells. One-way ANOVA was followed by post hoc tests for comparisons among groups. The values shown represent the mean ± standard error of the mean (SEM) of the data from three independent experiments. ^# p < 0.05 (compared to the control group alone); *p < 0.05 (compared to the model group alone).