背景:缺血性脑卒中严重威胁人类健康,缺血缺氧后星形胶质细胞大量表达脂质运载蛋白2加重脑损伤,但其具体机制并不清楚.羟基红花黄色素A具有抗缺血、抗氧化、抗血栓及抗炎等作用,其是否影响脑缺血缺氧后星形胶质细胞表达脂质运载蛋白2,目前尚不清楚. 目的:探究羟基红花黄色素A对脑缺血再灌注损伤后星形胶质细胞中脂质运载蛋白2表达的影响及机制. 方法:①将30只成年SD大鼠随机分成3组:假手术组、大脑中动脉闭塞再灌注组、羟基红花黄色素A组,后2组建立大脑中动脉闭塞再灌注模型,羟基红花黄色素A组在再灌注后以12 mg/kg的剂量腹腔注射羟基红花黄色素A.采用Longa评分法评估神经功能缺损程度,采用TTC染色法测定脑梗死体积,Western blot和免疫荧光检测JAK2/STAT3通路及脂质运载蛋白2的表达,ELISA法检测白细胞介素1β、白细胞介素6、肿瘤坏死因子α水平.②将星形胶质细胞分为4组:正常组、糖氧剥夺复糖氧组、羟基红花黄色素A组、AG490组,后3组建立糖氧剥夺复糖氧模型,在糖氧剥夺期间分别用75 μmol/L羟基红花黄色素A、10 μmol/L酪氨酸磷酸化抑制剂AG490处理星形胶质细胞8 h,进一步验证羟基红花黄色素A对脂质运载蛋白2的作用机制. 结果与结论:①与假手术组相比,大脑中动脉闭塞再灌注组大鼠脑梗死体积明显增加,并伴有神经功能损伤加重(P<0.01),羟基红花黄色素A治疗可以减小脑梗死体积,改善神经功能(P<0.01);②大脑中动脉闭塞再灌注组p-JAK2、p-STAT3和脂质运载蛋白2的表达高于假手术组(P<0.01),羟基红花黄色素A治疗后抑制了p-JAK2、p-STAT3和脂质运载蛋白2的表达(P<0.01);③大脑中动脉闭塞再灌注组炎性因子白细胞介素1β、白细胞介素6、肿瘤坏死因子α水平高于假手术组(P<0.01),羟基红花黄色素A治疗后抑制了白细胞介素1β、白细胞介素6、肿瘤坏死因子α表达(P<0.01);④体外实验糖氧剥夺复糖氧组p-JAK2、p-STAT3、脂质运载蛋白2的表达高于正常组(P<0.01),加入AG490后JAK2、STAT3磷酸化降低,脂质运载蛋白2表达被抑制(P<0.01).结果表明,羟基红花黄色素A可能通过调控JAK2/STAT3信号通路抑制缺血缺氧后星形胶质细胞中脂质运载蛋白2的表达,从而减轻脑损伤.
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.