It was found that melatonin at 4 mg/kg could exhibit the cardioprotective effects in rats with diet-induced obesity as shown by the decreased myocardial infarct sizes and insulin resistant, and the increased serum adiponectin, protein kinase B (PKB)/Akt, ERK42/44, GSK-3β and STAT3 without affecting the body weight or visceral adiposity [289]. Here, AKT1 is linked to obesity due to melanocortin 4 receptor deficiency.