Effect Of Apigenin And Luteolin On Ischemia/Reperfusion Induced Neuron Injury And Underlying Mechanism

Objective:Two flavones,apigenin and its hepatic metabolite Iuteolin,have considerable neuroprotective effects by its anti-oxidative mechanism.However,it is still unclear whether apigenin and luteolin can protect neurons against oxygen-glucose deprivation/reperfusion(OGD/R) induced injury by other mechanisms.Methods: After two hours oxygen-glucose deprivation and 24 hours reperfusion treatment or acute high concentration of glutamate treatment in primary cultured hippocampal neurons,the neuron viability,survival rate and apoptosis rate were evaluated by MTT assay,lactate dehydrogenase(LDH) leakage assay and hoechst staining,respectively. Activities of Na⁺/K⁺-ATPase and nitric oxide synthase(NOS) were also measured in OGD/R treated neurons.Male Sprague-Dawley rats were treated with ten minutes global cerebral ischemia and followed 24 hours reperfusion induced by Pulsinelli's 4-vessel occlusion,and the activity of Na⁺/K⁺-ATPase was estimated after I/R.Results: Treatment by OGD/R markedly reduced neuronal viability,increased LDH leakage rate and apoptosis rate.Application of apigenin or luteolin(10-100μmol·L^-1) during OGD inhibited OGD/R induced neuron injury and apoptosis in a dose-dependent manner,but they cannot reverse the injury induced by acute glutamate treatment(100μmol·L^-1).Furthermore,apigenin and luteolin did not affect the activities of total NOS and inducible NOS during OGD/R significantly,but preserved the activity of Na⁺/K⁺-ATPase supressed by global ischemia/reperfusion or OGD/R treatment. Inhibition of Na⁺/K⁺-ATPase with ouabain attenuated the protective effect afforded by apigenin and luteolin.Conclusions:The data provide the evidence that apigenin and luteolin have neuroprotective effect against OGD/R induced injury and the protective effect may be associated with their ability to improve Na⁺/K⁺-ATPase activity after OGD/R.