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目的 探讨脑缺血后脑组织内金属硫蛋白Ⅲ (MT Ⅲ )mRNA表达的诱导机制。方法 建立前脑缺血再灌注模型 ,用原位杂交技术观察大鼠海马结构MT ⅢmRNA表达变化规律 ;用Zn2 + 特异性荧光探针N (6 甲氧基 8 喹啉 ) P 甲苯磺胺 (TSQ)检测细胞内游离Zn2 + 含量的变化 ;观察侧脑室注入Zn2 + 螯合剂对大鼠前脑缺血再灌注后海马结构MT ⅢmRNA表达和胞内游离Zn2 + 含量的影响。结果 MT ⅢmRNA表达在脑缺血后不断增加 ,96h达高峰 ,7d恢复正常。前脑缺血再灌注后 48h ,海马CA3 区、齿状回门、CA1区光辉层和放射层的Zn2 + 荧光强度较缺血前减弱 ;再灌注后 72～ 96h ,CA1区锥体细胞层和齿状回门出现斑点状荧光并逐渐增多 ;再灌注后 7d基本恢复正常。膜不通透性Zn2 + 螯合剂乙二胺四乙酸二钠钙 (CaEDTA)能降低细胞内游离Zn2 + 含量 ,并抑制胞内MT ⅢmRNA的表达。结论 前脑缺血再灌注后 ,海马结构游离Zn2 + 含量的增加可能诱导MT ⅢmRNA表达。
Objective To investigate the induction of metallothionein Ⅲ (MT Ⅲ) mRNA in brain tissue after cerebral ischemia. Methods The model of forebrain ischemia-reperfusion was established. The expression of MT Ⅲ mRNA in hippocampal formation of rats was observed by in situ hybridization. The expression of MT III mRNA in hippocampal formation was detected by using the specific fluorescent probe N 2 (6 methoxy 8 quinoline) The content of free Zn2 + in the cells was detected. The effect of intracerebroventricular injection of Zn2 + chelator on the expression of MT Ⅲ mRNA and the intracellular free Zn2 + content in the hippocampus after forebrain ischemia-reperfusion was observed. Results The expression of MT Ⅲ mRNA increased continuously after cerebral ischemia, peaked at 96 hours and returned to normal after 7 days. 48h after forebrain ischemia, the fluorescence intensity of Zn2 + in hippocampal CA3 area, dentate gyrus, CA1 area and radiation layer was weaker than that before ischemia; 72-96h after reperfusion, the pyramidal cell layer and The dentate gyrus showed speckled fluorescence and gradually increased; 7d after reperfusion, returned to normal. Membrane impermeability Zn2 + chelator CaEDTA decreased the intracellular free Zn2 + content and inhibited the expression of intracellular MT Ⅲ mRNA. Conclusion The increase of free Zn2 + content in hippocampal formation may induce MT Ⅲ mRNA expression after forebrain ischemia-reperfusion.