BACKGROUND:Ischemic stroke is a serious threat to human health.After ischemia and hypoxia,astrocyte expresses lipocalin-2 in large amounts to aggravate brain injury,but the specific mechanism is not clear.Hydroxysafflor yellow A has anti-ischemia,anti-oxidation,anti-thrombosis and anti-inflammatory effects.However,whether hydroxysafflor yellow A affects the expression of lipocalin-2 in astrocytes after cerebral ischemia and hypoxia and its mechanism are not clear. OBJECTIVE:To investigate the effect and mechanism of hydroxysafflor yellow A on the expression of lipocalin-2 in astrocytes after cerebral ischemia and reperfusion. METHODS:(1)Thirty adult SD rats were randomly divided into three groups:sham operation group,middle cerebral artery occlusion and reperfusion group,and hydroxysafflor yellow A group.The middle cerebral artery occlusion and reperfusion model was established in the latter two groups,and hydroxysafflor yellow A group was intraperitoneally injected with 12 mg/kg hydroxysafflor yellow A after reperfusion.Longa score was used to evaluate the degree of neurological impairment.Infarct volume was determined by TTC staining.JAK2/STAT3 pathway and lipocalin-2 expression were detected by western blot assay and immunofluorescence.Levels of interleukin 1β,interleukin 6 and tumor necrosis factor α were detected by ELISA.(2)Astrocytes were divided into four groups:Normal group,glucose-oxygen deprivation group,hydroxysafflor yellow A group and AG490 group.In the latter three groups,glucose-oxygen deprivation and glucose-oxygen recovery models were established.Astrocytes were treated with 75 μmol/L hydroxysafflor yellow A and 10 μmol/L tyrosine phosphorylation inhibitor AG490 for 8 hours during glucose-oxygen deprivation,respectively.The mechanism of hydroxysafflor yellow A on lipocalin-2 was further verified. RESULTS AND CONCLUSION:(1)Compared with the sham operation group,cerebral infarction was significantly increased in the middle cerebral artery occlusion and reperfusion group,accompanied by aggravated neurological impairment(P<0.01).Hydroxysafflor yellow A treatment could reduce cerebral infarction volume and improve neurological function(P<0.01).(2)The expressions of p-JAK2,p-STAT3 and lipocalin-2 in the middle cerebral artery occlusion and reperfusion group were higher than those in the sham operation group(P<0.01).Hydroxysafflor yellow A treatment reduced the expressions of JAK2,STAT3 and lipocalin-2(P<0.01).(3)The expression levels of interleukin 1β,interleukin-6 and tumor necrosis factor α in the middle cerebral artery occlusion and reperfusion group were higher than those in the sham operation group(P<0.01).Hydroxysafflor yellow A inhibited the expressions of interleukin 1β,interleukin-6 and tumor necrosis factor α(P<0.01).(4)In vitro,the expressions of p-JAK2,p-STAT3 and lipocalin-2 in the glucose-oxygen deprivation group were significantly higher than those in the normal group(P<0.01).After adding AG490,the phosphorylation of JAK2 and STAT3 decreased,and the expression of lipocalin-2 was inhibited(P<0.01).The results suggest that hydroxysafflor yellow A may inhibit the expression of lipocalin-2 in astrocytes after ischemia and hypoxia by regulating the JAK2/STAT3 signaling pathway,thereby reducing brain injury.