The protection of carbamylated erythropoietin on focal ischemic brain injury

Abstract

Objective To study the protection and its mechanism of carbamylated erythropoietin (CEPO) on ischemic brain injury and to compare its function with erythropoietin (EPO).Methods Focal cerebral ischemia/reperfusion was induced by occlusion of the middle cerebral artery (MCAO) using the intraluminal filament technique.The expression of endothelial NO synthase (eNOS) and activated caspase-3 were detected with Western blot.The inducible NO synthase (iNOS) positive cells were detected by immunohistochemistry staining.The apoptotic cell was detected by TUNEL staining.Results The expression of eNOS, iNOS and activated caspase-3 in cerebral cortex significantly increased after MCAO.The influence of CEPO and EPO on eNOS in ischemic cortex were not significantly different.However, the expression of activated caspase-3 markedly dropped from 95.4%±16.7% in group NS to 43.5%±13.1% in group CEPO and 45.1%±11.2% in group EPO (t=5.99 and 6.13,P<0.01).Immunohistochemistry staining revealed iNOS positive cells in ischemic cortex was (3.1±1.9) cells/square, CEPO and EPO remarkably reduced them to (0.7±0.2) cells/square and (0.8±0.2) cells/square, respectively (t=3.08 and 2.95, P < 0.05).The apoptotic cells in ischemic cortex fell from (94.2±15.2) cells/square in group NS to (40.5±9.8) cells/square in group CEPO (t=7.27, P < 0.01), the anti-apoptosis by EPO was similar to CEPO.Conclusion CEPO and EPO have the similar function of anti-apoptosis by inhibiting expression of activated caspase-3 and iNOS. Key words: Brain ischemia; Reperfusion; Erythropoietin; Nitric oxide synthase; Caspase 3