大鼠全脑缺血再灌注损伤对海马CA1区胶质细胞谷氨酸转运体1表达的影响

Effect of glial glutamate transporter-1 expression in hippocampal CA1 region during global cerebral ischemia reperfusion injury in rats

目的观察大鼠全脑缺血再灌注损伤对海马CA1区胶质细胞谷氨酸转运体1(glial glutamate transporter-1, GLT-1)表达的影响。方法雄性Wistar大鼠90只,随机分为三组:对照组(C组, n=6),不做处理;假手术组(S组, n=42),凝闭双侧椎动脉,48 h后假手术操作;缺血再灌注组(I/R组, n=42),采用四血管阻断法制备大鼠全脑缺血再灌注模型。于缺血再灌注即刻(0 h)、8 h、16 h、1 d、3 d、5 d、7 d断头取材,通过硫堇染色观察海马病理学变化和免疫组化及Western blot技术观察GLT-1、Bax和Bcl-2蛋白的表达情况。结果与C组比较,S组大鼠海马CA1区7 d病理分级(HG)和神经元密度(ND)差异无统计学意义(0级 vs. 0~Ⅰ级,214±3.7 vs. 206±4.6,P>0.05);各时间点S组大鼠海马CA1区GLT-1、Bcl-2、 Bax增多(P<0.05)。与S组比较,I/R组大鼠海马CA1区7 d HG显著升高(0~Ⅰ级 vs.Ⅲ级), ND显著降低(206±4.6 vs. 42±3.4,P<0.05);各时间点I/R组GLT-1、Bcl-2表达和Bcl-2/Bax比值降低,而Bax表达增加(P<0.05)。结论大鼠脑缺血再灌注损伤引起海马CA1区GLT-1表达下调,该作用可能是缺血再灌注损伤作用机制之一。

Objective To observe the effect of glutamate transporter -1( GLT - 1 ) dynamic expression of hippocampal CAI region caused by global cerebral ischemia - reperfusion injury in rats. Methods Ninety male Wistar rats were randomly divided into three groups: control group ( group C, n =6): without any treatment. Sham group (group S, n = 42): occluded bilateral vertebral arteries and underwent sham operation 48 hours later. Ischemia - reperfusion group ( I/R group, n =42): The rat model of global cerebral ischemia 一 reperfusion was established by four - vessel occlusion. The rats were decapitated in given time points, immediately after ischemia (0 h), 8 h, 16 h, 1 d, 3 d, 5 d, 7 d, and the histological changes of hippocampus and expressions of GLT - 1, Bax and Bel - 2 were observed by thionine staining, immunohistochemistry and Western blot techniques. Results Compared with group C, there was no significant difference in histological grade ( HG) and neuron density ( ND) in hippocampal CAI region at 7 d [ group C: HG 0, ND: 214 ±3.7 vs. group S: HG 0 - I , ND: 206. 0 ±4. 6, P > 0. 05 ] while expression of GLT - 1, Bel - 2 and Bax in hippocampal CAI region increased in group S ( P < 0. 05 ). Compared with group S, HG (IQ ) increased and ND (42 ± 3. 4 ) decreased significantly in hippocampal CAI region in I/R group at 7 d ( P < 0. 05 );GLT - 1, Bel - 2 expression and Bel 一 2/Bax ratio decreased while Bax expression increased ( P < 0. 05 ). Conclusion Cerebral ischemia - reperfusion injury causes down - regulation of GLT 一 1 expression in hippocampal CAI region, which may be one of the mechanisms of ischemia - reperfusion injury.