A murine model of ischemia–reperfusion: the perfusion with leptin promotes the apoptosis-related relocation of mitochondrial proteins Bax and cytochrome c

Background Leptin exerts both protective and deleterious effects on the heart; the first occurs under hypoxia- or ischemia-associated damage, the second is a pro-hypertrophic factor on cardiomyocytes. Therefore, leptin could represent a link between obesity and cardiovascular diseases. The study aimed to investigate the effect of leptin—the same concentration that is frequently measured in obesity and induces cardiac hypertrophy—on murine hearts following an episode of ischemia–reperfusion; moreover, we evaluated the heart's performance, hypertrophy, and activation of apoptosis. Rat hearts were perfused continuously with or without 3.1 nM leptin for one h before and 1 h after an episode of ischemia. Cardiac performance was evaluated, homogenates and mitochondria were prepared for western blot analysis of cardiac actin, leptin receptor, STAT3, pSTAT3, and apoptosis-related proteins Bax, Bcl-2, cytochrome c, and caspase 3. Results Leptin worsened heart recovery after ischemia ( p < 0.05 Control vs IR + Lep of Heart Perform, Fig. 2 ). Although no hypertrophic response was observed, leptin induced the migration of Bax to the mitochondria and the release of cytochrome c into the cytosol ( p < 0.05 Control vs IR + Lep, Fig. 5 ), essential events in the intrinsic/mitochondrial apoptosis. Conclusions Our results indicate that the presence of leptin for 1 h before and after the ischemic insult reduces heart recovery and amplifies apoptotic signaling through the mitochondrial pathway.