天麻素对脑缺血再灌注小鼠海马新生神经元的保护作用

目的:探讨不同剂量天麻素(Gastrodin,GAS)对缺血再灌注模型小鼠海马新生神经元的保护作用及其可能机制。方法:将50只C57BL/6小鼠随机分为假手术组(Sham)、模型组(MCAO+Vehicle)、模型+天麻素低剂量(10 mg/kg)组(MCAO+GAS(L)),模型+天麻素中剂量(50 mg/kg)组(MCAO+GAS(M)),模型+天麻素高剂量(100 mg/kg)组(MCAO+GAS(H))。除Sham组接受假手术外(皮肤切开,分离颈动脉),分别对MCAO组及MCAO+GAS各组行右侧颈内动脉栓线术,造成并保持大脑中动脉闭塞(MCAO)1 h。术后,Sham组和MCAO组即刻腹腔注射生理盐水(0.1 m L/kg),MCAO+GAS各组注射不同剂量天麻素,每24小时重复给药1次,连续7天。最后一次注射24 h后,对各组小鼠的神经功能进行评分,之后处死动物取脑组织,通过HE、免疫荧光染色以及Western Blot观察和比较各组小鼠海马形态学和DCX的表达水平。结果:(1)术后第7天,MCAO+Vehicle组小鼠神经功能评分(3.2±0.63)显著高于假手术组、MCAO+GAS(M)(1.8±0.63)和MCAO+GAS(H)组(P0.05)。(2)术后第7天,与假手术组相比较,MCAO+vehicle组海马颗粒细胞排列不规则,核稍大且固缩深染,齿状回部有较多空洞;与MCAO+vehicle组比较,MCAO+GAS(H)组海马空洞样改变减少,细胞排列较整齐,胞膜较完整,核结构较清晰。(3)术后第7天,与假手术组相比较,DCX染色阳性细胞数显著减少,而MCAO+GAS(M)组DCX染色阳性细胞数(183±64.5)和MCAO+GAS(H)组DCX染色阳性细胞数(195±93.68)显著高于MCAO+Vehicle组。MCAO+Vehicle组海马的DCX表达水平显著低于假手术组及MCAO+GAS(M)组和GAS(H)组(P0.01)。结论:天麻素可能通过上调海马DCX的表达水平,调节海马神经发生,进而对缺血性脑卒中后再灌注发挥神经保护作用。

Protective Effects of Gastrodin on the Hippocampal Newborn Neurons after Cerebral Ischemia-Reperfusion

Objective:To observe the effects of different concentrations of gastrodin (GAS) on the neural function and the expression of DCX in the hippocampus after cerebral ischemia-reperfusion in mice.Methods:50 male C57BL/6J mice were randomly divided into five groups: Sham, MCAO+Vehicle, MCAO+GAS (L, L=10 mg/kg), MCAO+GAS (M, M=50 mg/kg), MCAO+GAS (H, H=100 mg/kg). The mice in Sham group received fake surgery, while the mice in MCAO and MCAO+GAS group were exposed to MCAO. Mice were injected intraperitoneally with saline or different doses of GAS 1 h after surgery once daily for 7 consecutive days, and then the neural function scores were assessed before execution. The hippocampal structure was observed by hematoxylin-eosin staining and immunohistochemistry, and the expression of DCX was also detected byWestern blotting.Results:(1) The neural function score in MCAO+Vehicle group (3.2± 0.63) was higher than that of Shamand MCAO+GAS (M) (1.8± 0.63) or MCAO+GAS (H) group on the 7th day after reperfusion (P<0.05). (2) Compared to Sham group, hippocampal granule cell layer was arranged irregularly in MCAO+Vehicle group on the 7th day after reperfusion, there also appeared pyknosis and void like changes. The void like changes were reduced and granule cell layer was more clear in MCAO+GAS (H) group in comparison with MCAO+Vehicle group. (3) After reperfusion, MCAO+Vehicle group showed less number of DCX positive cell in comparison with Sham group. Moreover, MCAO+GAS (M) group (183± 64.5) and MCAO+GAS (H) group (195± 93.68) showed more number of DCX positive cell in comparison with MCAO+Vehicle group on the 7th day. Consistent with the result of immunohistochemistry, the expression of DCX in MCAO+Vehicle was significantly less than that of Sham, MCAO+GAS (M) and MCAO+GAS (H) groups (P<0.01).Conclusion:Gastrodin could regulate neurogenesis by up-regulating the expression of DCX in hippocampus of MCAO mice, reduce its neurologic impairment in a certain does, and show some protect effects of cerebral ischemia.