Objective To study the effects of melatonin (MT) on myocyte
apoptosis and the
expression of apoptosis associated genes
in rat hearts with myocardial ischemia and reperfusion (I/R). Methods I/R models were established by a ligation or release of left coronary artery in rats. Myocyte
apoptosis and the protein
expression of bcl 2 and bax genes were detected by terminal deoxynucleotide transferase (TdT) mediated dUTP nick and labeling (TUNEL) and immunohistochemistry respectively. Results Compared with sham operated group, the apoptotic index (AI) and the positive expression index (PEI) of the bcl 2 and bax protein in myocytes were increased significanly in I/R group. Compared with I/R group, AI and PEI of bax protein were decreased obviously and the protein expression of bcl 2 gene was upregulated in MT group (21 96±7 68 vs 12 17±6 45,18 59±5 68 vs 9 71±2 82,7 33±2 05 vs 13 45±2 76, respectively). Conclusion MT can protect myocardium against ischemia and reperfusion injury by inhibiting myocyte apoptosis, downregulate the protein expression of bax gene and upregulate the protein expression of bcl 2 gene.