Metformin Attenuates Postinfarction Myocardial Fibrosis and Inflammation in Mice

Figures

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  Figure 1. Metformin treatment prevents fibrotic remodeling in postinfarcted myocardium. (A) Representative images of wheat germ agglutinin (WGA) staining of frozen heart tissue sections; scale bar is 25 µm. Frozen sections from vehicle- or metformin-treated mice subjected to 30 min of cardiac ischemia and 14 days of reperfusion were stained with WGA. Metformin treatment (5 mg/kg, i.p.) started 15 min after the onset of reperfusion and continued for 14 days. (B) Quantification of fibrotic area from (A), n = 3–5. Data are presented as mean ± SEM. One-way ANOVA followed by Bonferroni’s post hoc test: *** p < 0.001 vs. control (C), §§§ p < 0.001 vs. I/R.

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  Figure 2. Metformin attenuates cardiac fibrosis in postinfarcted myocardium. Metformin treatment prevents fibrotic remodeling in postinfarcted myocardium. (A) Representative images of Sirius Red staining of frozen heart tissue sections from vehicle- or metformin-treated mice subjected to 30 min of cardiac ischemia and 14 days of reperfusion. Metformin treatment (5 mg/kg, i.p.) started 15 min after the onset of reperfusion and continued for 14 days. (B) Quantification of fibrotic area from (A), n = 4–5. Data are presented as mean ± SEM. One-way ANOVA followed by Bonferroni’s post hoc test: ** p < 0.01 vs. control (C), § p < 0.001 vs. I/R.

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  Figure 3. Metformin treatment downregulates profibrotic genes in postinfarcted myocardium. (A) qRT-PCR quantification of the expression level of the myofibroblast marker αSMA. (B) qRT-PCR quantification of the expression level of the collagen type III. Data are presented as mean ± SEM. One-way ANOVA followed by Bonferroni’s post hoc test: * p < 0.05 vs. control (C), ** p < 0.01 vs. control (C), § p < 0.05 vs. I/R.

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  Figure 4. Metformin exerts anti-inflammatory activity in postinfarcted myocardium. (A) CD68 immunostaining was performed in order to detect inflammatory cell populations in cardiac sections from vehicle- or metformin-treated mice subjected to 30 min of cardiac ischemia and 14 days of reperfusion. Metformin treatment (5 mg/kg, i.p.) started at 15 min of reperfusion and continued for 14 days. Scale bar is 100 µm. (B) Quantification of inflammatory cells from (A), n = 4–5. One-way ANOVA followed by Bonferroni’s post hoc test: *** p < 0.001 vs. control (C), §§§ p < 0.001 vs. I/R.

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  Figure 5. Effect of metformin treatment on cardiac expression of CD68, IL-6 and TNF-αin a mouse model of I/R injury. qRT-PCR quantification of the expression level of CD68 (A), IL-6 (B) and TNF-α (C), n = 4–5. Data are presented as mean ± SEM. One-way ANOVA followed by Bonferroni’s post hoc test: * p < 0.05 vs. control (C), ** p < 0.01 vs. control (C), § p < 0.05 vs. I/R.

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  Figure 6. Echocardiographic functional parameters of mice after 14 days of cardiac I/R. (A) Representative 2D-M-Mode echocardiographic images of vehicle- or metformin-treated mice subjected to 14 days of I/R. (B) Ejection fraction (EF) and (C) fractional shortening (FS) invehicle- or metformin-treated I/R mice (n = 3 per group). Data are presented as mean ± SEM. One-way ANOVA followed by Bonferroni’s post hoc test: *** p < 0.001, §§§ p < 0.001 vs. control (C).