Curcumin protects against regional myocardial ischemia/reperfusion injury through activation of RISK/GSK-3β and inhibition of p38 MAPK and JNK.

BACKGROUND: Curcumin, the active ingredient of turmeric (Curcuma longa), is known to have anti-inflammatory and antioxidative properties. The present study was aimed to determine the effect of curcumin in regional myocardial ischemia/reperfusion (I/R) injury and its underlying mechanisms involving the role of prosurvival kinases and apoptotic kinases.

METHODS: Sprague-Dawley rats (n = 109) subjected to a 30-minute left anterior descending coronary artery (LAD) occlusion followed by reperfusion were assigned to receive saline (control), curcumin (100 mg/kg), wortmannin (inhibitor of phosphatidylinositol-3-OH kinase [PI3K]-Akt), wortmannin + curcumin, U0126 (inhibitor of extracellular signal-regulated kinase [ERK1/2]), U0126 + curcumin, SB216763 (inhibitor of glycogen synthase kinase [GSK-3β]), and SB216763 + curcumin 20 minutes before LAD occlusion. Infarct size was measured after 2 hours of reperfusion by triphenyl tetrazolium chloride staining. The phosphorylation of Akt, ERK1/2, GSK-3β, p38, and c-Jun N-terminal kinases (JNK) was determined by immunoblotting after 10 minutes of reperfusion.

RESULTS: Curcumin significantly reduced the infarct size compared with the control (33.1% ± 6.2% vs 50.1% ± 3.9%; P < .05). Wortmannin or U0126 alone did not affect the infarct size but abolished the curcumin-induced cardioprotective effect. Curcumin significantly enhanced the phosphorylation of Akt, ERK1/2, and GSK-3β, while it reduced that of p38 and JNK. Wortmannin or U0126 abolished enhanced phosphorylation of GSK-3β induced by curcumin. SB216763 alone or combined with curcumin reduced the infarct size and enhanced phosphorylation of GSK-3β compared with the control.

CONCLUSIONS: Preconditioning by curcumin effectively protects against regional myocardial I/R injury through the activation of prosurvival kinases involving PI3K-Akt, ERK1/2, and GSK-3β, and attenuation of p38 and JNK.