Protective effect of peroxisome proliferator-activated receptor α activation against cardiac ischemia-reperfusion injury is related to up-regulation of uncoupling protein-3

Abstract

Peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated nuclear receptor involved in transcriptional regulation of lipoprotein and fatty acid metabolism. PPARα activation was reported to have cardioprotective effect, while its mechanism remains elusive. This study investigated the effect of PPARα activation on expression of uncoupling protein (UCP) and protection against cardiac ischemia-reperfusion injury in vitro and in vivo.H9c2 (neonatal rat cardiac myoblast) cells were incubated for 24 h with medium containing WY-14643, a PPARα ligand, or vehicle. UCP expression, intracellular reactive oxygen species (ROS) production and cell survival against hypoxia-reoxygenation were determined. WY-14643 increased the transcription of UCP3 mRNA and UCP3 protein level in H9c2 cells. The expression of UCP2 was not altered by WY-14643 treatment. WY-14643 decreased H2O2- or hypoxia-stimulated intracellular ROS production. Cell survival assessed by MTT assay or cell counting showed that WY-14643 treated H9c2 cells were more resistant against hypoxia-reoxygenation injury than the untreated cells. Knocking-down UCP3 by siRNA prevented WY-14643 from decreasing the production of ROS. UCP3 siRNA abolished the effect of WY14643 on cell viability against hypoxia-reoxygention injury.Degree of myocardial infarction following left anterior descending coronary artery occlusion and UCP expression was measured in rats treated with WY-14643 (20 mg/kg) or vehicle. Hemodynamic variables and 3-lead electrocardiogram were also recorded during ischemia-reperfusion. In vivo, UCP3 expression was increased in rats treated with WY-14643. Myocardial infarct size was smaller in rats treated with WY-14643 compared with those treated with vehicle (76 ± 8% vs. 42 ± 12%, control vs. WY-14643, respectively, p < 0.05). During reperfusion, the incidence of arrhythmia was higher in control group compared with WY-14643 group (9/10 vs. 3/10, p < 0.05).In conclusion, PPARα activation by WY-14643 conferred the cell protective effect against hypoxia-rexoygenation. Administration of PPARα agonist WY-14643 also decreased the size of myocardial infarction and the incidence of reperfusion-induced arrhythmia. It is suggested that WY-14643 increases UCP3 expression resulting in concomitant attenuation of ROS production.