线粒体钙单向转运体对大鼠脑缺血/再灌注损伤线粒体分裂的影响

The role of mitochondrial calcium uniporter in regulating mitochondria fission in vivo cerebral cortex of rats

目的 探讨线粒体钙单向转运体（mitochondrail calcium uniporter,MCU）在大鼠短暂性脑缺血/再灌注损伤（ischemia/reperfusion injury,I/RI）模型中对线粒体分裂的影响. 方法 将80只健康雄性Wistar大鼠采用完全随机分组法分成4组（每组20只）：A组：假手术组;B组：脑缺血/再灌注（ischemia/reperfusion,I/R）＋钌红（MCU抑制剂）处理组;C组,脑I/R＋精胺（MCU激动剂）处理组;D组：脑I/R组.采用线栓法建立大鼠大脑中动脉栓塞（middle cerebral artery occlusion,MACO）模型,缺血2h再灌注24 h后对大鼠行神经行为学评分,取缺血侧脑组织测定其线粒体内钙含量、钙调神经磷酸酶（calcineurin,CN）活性、线粒体分裂相关蛋白Drp1的表达量,并观察线粒体形态. 结果 与D组比较,B组钌红预处理可以改善大鼠脑I/RI引起的神经功能学障碍（1.5±0.7）（P＜0.01）,降低脑缺血侧大鼠线粒体自由钙含量（265±8） nmol/L（P＜0.01）,降低CN活性（0.520±0.036） U/mgprot （P＜0.01）及Drp1的表达（1.24±0.11） （P＜0.01）,并减轻线粒体损伤;与D组比较,C组精胺预处理得到与钌红预处理相反的结果. 结论 MCU的开放状态可能影响大鼠脑I/RI线粒体分裂,抑制MCU开放可以抑制线粒体分裂,从而减轻大鼠脑I/RI,保护脑组织.

Objective To investigate the effect of mitochondrial calcium uniporter （MCU） on mitochondrial fission in an in vivo model of cerebral ischemia/reperfusion injury （I/RI）.Methods Eighty rats were randomly divided into 4 groups：group A：sham-operated; group B：Ruthenium red ＋ischemia/reperfusion （I/R）,group C：spermine ＋I/R,group D：I/R.The middle cerebral artery occlusion （MCAO） was occluded for 2 h and reperfused for 24 h.The neuropsychological scores,mitochondrial free calcium contents,the calcineurin（CN） activities,Drp1 expression and mitochondrial ultrastructure were observed.Results Compared with group D,Ruthenium red preconditioning in group B improved neuropsychological score （1.5±0.7） （P＜0.01）,decreased the mitochondrial free calcium content （265±8） nmol/L （P＜0.01）,CN enzyme activities （0.520±0.036） U/mgprot （P＜0.01） and Drp1 expression （1.24±0.11）（P＜0.01）,and improved the mitochondrial ultrastructure.While group C got the opposite results.Conclusions The activity of mitochondrial calcium uniporter has effects on mitochondrial fission this relationship between MCU and mitochondrial fission may possibly provide a protection against I/RI.