STRUCTURE & FUNCTION OF MITOCHONDRIA

短暂性脑缺血使神经元去极化， 细胞外谷氨酸和细胞内钙， 在缺血后阶段的突触功效。 的影响 短暂性缺血等同于强缺血性脑缺血 在受损区域进行电刺激 我们提出 有证据表明，短暂性缺血诱导了明显的生化和 突触后密度（PSD）的超微结构变化。 瞬态 结扎大鼠双侧颈总动脉造成缺血 动脉阻断15分钟，然后再灌注4小时。 在这些 动物，在皮质分离部分中测量的PSD产量 比对照组增加了2.49 ± 10.23倍。 蛋白质 再灌注的PSD的组成被重构，如所证明的 考马斯蓝染色和蛋白质印迹法。 最显著的 在再灌注的PSD中蛋白激酶的积累 包括p38激酶、JNK 1、gp 145 trkB、CaM激酶II、蛋白激酶C 和酪氨酸激酶。 PSD蛋白的磷酸化状态 在再灌注后也显著增加。 这些生化 改变与超微结构改变一致 在为电子显微镜制备的PSD中观察到。 PSD分离自 缺血后的动物比缺血后的动物更长更厚， 对照 组织中PSD结构也发生了显著改变 再灌注动物的皮质切片， 磷钨酸选择性染色PSD。 PSD明显 比对照组更厚、形状更不规则、更不紧凑。 我们的结论是，信号转导分子在PSD中的对接， PSD蛋白的磷酸化是改变的重要因素 在刺激后的突触效能。 这项工作发表在 在Hu等人中，神经科学杂志，18：625-633，1998. 在过去的一年里，我们 对CA 1中PSD的变化进行了更详细的定量分析 和海马齿状回。 使用厚切片， IVEM，我们进行了断层重建的突触在 缺血组和对照组大鼠海马在不同时间点 再灌注 这些重建清楚地表明， CA 1区在缺血脑中的结构比在缺血脑中更松散。 控制大脑 3D图像表明，CA 1中的突触 在明显的细胞死亡之前经历退行性变化。 这 这项工作在神经科学学会年会上发表， 一份手稿已经提交给了《神经科学杂志》。

Transient cerebral ischemia depolarizes neurons, increases extracellular glutamate and intracellular calcium, and changes synaptic efficacy in the post-ischemic phase. The effects of transient ischemia are equivalent to those produced by strong electrical stimulation within the compromised area. We present evidence that transient ischemia induces marked biochemical and ultrastructural changes in postsynaptic densities (PSDs). Transient ischemia was induced in rats by bilateral ligation of the carotid arteries for 15 min followed by 4 hr of reperfusion. In these animals, the yield of PSDs as measured in isolated fractions of cortex was increased by a factor of 2.4910.23 over controls. The protein composition of the reperfused PSDs was reconstituted as demonstrated by Coomasie blue staining and Western Blots. The most remarkable changes were an accumulation of protein kinases in reperfused PSDs including p38-kinase, JNK1, gp145trkB, CaM-kinase II, protein kinase C and tyros ine kinases. The phosphorylation states of PSD proteins were also markedly increased following reperfusion. These biochemical alterations were consistent with ultrastructural modifications observed in PSDs prepared for electron microscopy. PSDs isolated from post-ischemic animals were longer and thicker than those from controls. PSD structure was also dramatically altered in tissue sections from the cortex of reperfused animals stained with phosphotungstic acid to selectively stain PSDs. PSDs were noticeably thicker, more irregular in shape and less compact than in controls. We conclude that docking of signal transduction molecules in PSDs and phosphorylation of PSD proteins are important contributors to changes in synaptic efficacy following stimulation. This work was published in Hu et al., J. Neurosci., 18: 625-633, 1998. In the past year, we performed a more detailed quantitative analysis of PSD changes in CA1 and dentate gyrus in ischemic hippocampus. Using thick sections and IVEM, we performed tomographic reconstructions of synapses in the hippocampus of ischemic and control rats at different time points of reperfusion. These reconstructions clearly showed that synapses in area CA1 were more loosely configured in the ischemic brain than in control brains. The 3D images suggest that synapses in CA1 are undergoing degenerative changes prior to obvious cell death. This work was presented at the Annual Society for Neuroscience meeting and a manuscript has been submitted to the Journal of Neuroscience.