PPARα is involved in the multitargeted effects of a pretreatment with atorvastatin in experimental stroke

There is now substantial data in the literature showing that statins can protect against cerebral ischemia. This neuroprotective potency is related to their pleiotropic effects that modulate various pathways implicated in the pathophysiology of stroke. It has been demonstrated that statins exert anti-inflammatory and vasculoprotective effects, thus contributing to a reduction in infarct size. The underlying mechanisms are still incompletely known. As a cross-talk between statins and the nuclear receptor PPARα has been described, we hypothesized that this cross-talk is necessary to neuroprotection in stroke. We studied the effects of a 14-day preventive atorvastatin treatment (10 mg/kg/day) on C57Bl6 wild-type and PPARα-KO mice submitted to experimental stroke. PPARα was involved in the atorvastatin-induced neuroprotective effect, as confirmed by the measurement of infarct volumes. We also evidenced that the anti-inflammatory action of atorvastatin is mediated, at least partly, by PPARα. The decrease in IL-6 plasmatic levels was PPARα dependent. The cerebral expression of the adhesion molecules ICAM-1 and vascular cell adhesion molecule was reduced by the atorvastatin treatment, and this effect was PPARα dependent in the cortex but not in the striatum of treated animals. Atorvastatin also diminished the cerebral expression of iNOS in the cortex, but had no effect in the striatum of treated mice, whatever the PPARα status. At the vascular level, we found that the atorvastatin-related endothelial nitric oxide synthase upregulation was regulated by PPARα in the aorta, while there was no effect in the brain. We demonstrate here that PPARα is a key mediator of the multitargeted neuroprotective effects of statins in stroke.