Effect of sufentanil preconditioning on expression of Toll-like receptor 4 in myocardium during myocardial ischemia-reperfusion in rats

Objective To investigate the effect of sufentanil preconditioning on the expression of Toll-like receptor 4 (TLR4) in myocardium during myocardial ischemia-reperfusion (I/R) in rats.Methods Thirty-six male Sprague-Dawley rats,weighing 250-300 g,were randomly divided into 3 groups (n =12 each):sham operation group (group S),I/R group and sufentanil preconditioning group (group SPC).Myocardial ischemia was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 2 h of reperfusion.In group SPC,the rats were subjected to 3 consecutive cycles of 5 min sufentanil infusion at 0.2 μg· kg-1 ·min-1 via the femoral vein at 5 min interval before ischemia.In groups S and I/R,the rats were subjected to the equal volume of normal saline instead.HR and mean arterial pressure (MAP) were recorded at 30 min before ischemia (T0),immediately before ischemia (T1),at 30 min of ischemia (T2),and at 30 and 120 min of reperfusion (T3-4).At the end of reperfusion,blood samples were obtained to determine the serum concentration of TNF-α.The rats were then sacrificed and hearts were removed for measurement of myocardial infarct size and expression of TLR4 and NF-κB p65 in myocardium (using Western blot).Results There was no significant difference in HR among the three groups (P ＞ 0.05).Compared with group S,MAP was significantly decreased at T2-4,the serum concentration of TNF-α was increased,and the expression of TLR4 and NF-kB p65 protein in myocardium was upregulated in groups I/R and SPC (P ＜ 0.01).Compared with group I/R,no significant difference was found in MAP at all time points (P ＞ 0.05),and myocardial infarct size was significantly decreased,serum concentrations of TNF-α were decreased,and the expression of TLR4 and NF-κB p65 protein in myocardium was down-regulated in group SPC (P ＜ 0.01).Conclusion The mechanism by which sufentanil preconditioning alleviates myocardial I/R injury may be related to down-regulation of TLR4 expression in rat myocardium. Key words: Sufentanil;  Ischemic preconditioning;  Toll-like receptor 4;  Myocardial reperfusion injury