RESUMO
To study the protective effect of rosuvastatin on ischemic brain injury and its mechanism, focal cerebral ischemia/reperfusion was induced by occlusion of the middle cerebral artery (MCA) using the intra-luminal filament technique. The cerebral blood flow was monitored with laser-Doppler flowmetry (LDF). The slices of brain tissue were stained with cresyl-violet. The cerebral volume of infarction and edema were quantified with ImageJ software. The expressions of endothelial NO synthase (eNOS) and activated caspase-3 were detected with Western blot. The inducible NO synthase (iNOS) positive cells were immunohistochemically observed. The results demonstrated that rosuvastatin (20 mg/kg) could remarkably decrease infarct volume and cerebral edema after MCAO 90 min/reperfusion 24 h. Western blots showed that the expression of eNOS in cerebral cortex before and after ischemia was (100+/-43.3) %, (1668.9+/-112.2) % respectively (P<0.001), rosuvastatin significantly up-regulated the expression of eNOS in non-ischemic cortex (P<0.001), whereas in ischemic cortex of rosuvastatin group the expression of eNOS was (1678.8+/-121.3) %. There was no expression of activated caspase-3 in non-ischemic cortex, nonetheless the expression of activated caspase-3 increased after ischemia, and rosuvastatin significantly diminished it (P<0.01). Immunohistochemistry revealed no iNOS-positive cells in non-ischemic brain area, while in ischemic brain area the number of iNOS positive cells went up, and rosuvastatin could significantly reduced them. Consequently, the mechanisms of rosuvastatin's neural protection on ischemic brain injury are to enhance expression of eNOS, to inhibit expression of iNOS and activated caspase-3.