The obesity-associated hormone leptin has been shown to exert an infarct size-limiting effect after 35 min global ischaemia and 35 min reperfusion in non-obese C57Bl/6 mice [97]; however, leptin treatment was associated with reduced levels of phosphorylated and total STAT3 after myocardial infarction in this study [97]. Here, STAT3 is linked to obesity due to melanocortin 4 receptor deficiency.