Metformin mitigates apoptosis in ischemic myocardium

Area of Science:

• Cardiovascular Research
• Metabolic Syndrome
• Pharmacology

Background:

• Metformin demonstrates a survival advantage in patients with cardiovascular disease, independent of its insulin-sensitizing effects.
• The precise cardioprotective mechanism of metformin remains to be elucidated.

Purpose of the Study:

• To investigate the impact of metformin on cardiac apoptosis pathways.
• To evaluate these effects in both ischemic and non-ischemic cardiac tissues.
• To utilize a swine model of metabolic syndrome for this evaluation.

Main Methods:

• Ossabaw miniswine were assigned to three dietary groups: regular diet, high-cholesterol diet, or high-cholesterol diet with metformin.
• Chronic myocardial ischemia was induced via ameroid constrictor placement in the left circumflex coronary artery.
• Cardiac tissue was harvested after 7 weeks post-constriction for analysis.

Main Results:

• Metformin significantly upregulated prosurvival proteins (ERK, NF-κB, p-eNOS, P38) in ischemic myocardium.
• Metformin inhibited proapoptosis proteins (FOXO3, caspase 3) and reduced overall myocyte apoptosis.
• No significant changes were observed in arteriolar/capillary density, fibrosis, or collagen deposition.

Conclusions:

• Metformin selectively modulates the cardiac apoptosis pathway by inhibiting FOXO3 and decreasing cleaved caspase 3.
• Upregulation of cardioprotective mitogen-activated protein kinases (p38, ERK1/2) by metformin was observed.
• Altered apoptosis pathway activation in ischemic myocardium represents a potential cardioprotective mechanism of metformin.