Delta Opioid activation of the Mitogen-activated protein kinase cascade does not require transphosphorylation of Receptor Tyrosine Kinases

Background

The peroxisome proliferator-activated receptor α (PPARα) plays an important role in the metabolism of lipoproteins and fatty acids, and seems to protect against the development of atherosclerosis. To evaluate the possible protective role of PPARα on cardiovascular function, the effect of the PPARα agonist, fenofibrate was assessed with respect to ischaemia/reperfusion injury and endothelial function in mice.

Results

Fenofibrate treatment reduces myocardial infarction size and improves post-ischaemic contractile dysfunction. Hearts from PPARα null mice exhibit increased susceptibility to ischaemic damages and were refractory to protection by fenofibrate treatment suggesting that the beneficial effects of fenofibrate were mediated via PPARα. Furthermore, fenofibrate improves endothelium- and nitric oxide-mediated vasodilatation in aorta and mesenteric vascular bed. A decreased inhibitory effect of reactive oxygen species in the vessel wall accounts for enhanced endothelial vasodilatation. However, the latter cannot be explained by an increase in nitric oxide synthase expression nor by an increase sensitivity of the arteries to nitric oxide.

Conclusions

Altogether the present data suggest that fenofibrate exerts cardioprotective effect against ischaemia and improves nitric oxide-mediated response probably by enhancing antioxidant capacity of the vessel wall. These data underscore new therapeutic perspectives for PPARα agonists in ischaemic myocardial injury and in cardiovascular diseases associated with endothelial dysfunction.