Ischemic preconditioning protects against myocardial ischemia-reperfusion injury through inhibiting toll-like receptor 4/NF-κB signaling pathway in rats.

OBJECTIVE

To investigate whether the protection of ischemic preconditioning (IPC) against myocardial ischemia/reperfusion (I/R) injury is mediated by toll-like receptor 4 (TLR4)/NF-κB pathway, and whether these effects are related to the release of calcitonin gene-related peptide (CGRP).

METHODS

Sprague-Dawley rats were subjected to 60 min of ligation of the left anterior descending coronary artery followed by 3 h of reperfusion to induce I/R injury. IPC was performed by 4 cycles of 3-min left coronary artery occlusion followed by 5-min reperfusion before the I/R. The expression of TLR4 mRNA was determined by RT-PCR. TLR4 and NF-κB protein expression were analyzed by immunohistochemistry. Myocardial infarct size, CGRP concentration in plasma and activity of creatine kinase in serum were also measured.

RESULTS

IPC significantly reduced the infarct size and creatine kinase activity concomitantly with the increase in plasma CGRP concentration. The expressions of TLR4 protein and mRNA and NF-κB protein were increased by myocardial I/R injury, and dramatically inhibited by IPC.

CONCLUSION

IPC protects against myocardial I/R injury by inhibition of TLR4/NF-κB pathway. These effects are related to the increased the release of CGRP.