Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
Neuroscience. 2010 May 5;167(2):414-27. doi: 10.1016/j.neuroscience.2010.02.028. Epub 2010 Feb 16.
Head trauma and acute disorders often instantly compress the cerebral cortex and lead to functional abnormalities. Here we used rat epidural bead implantation model and investigated the immediate changes following acute compression. The dendritic arbors of affected cortical pyramidal neurons were filled with intracellular dye and reconstructed 3-dimensionally for analysis. Compression was found to shorten the apical, but not basal, dendrites of underlying layer III and V cortical pyramidal neurons and reduced dendritic spines on the entire dendritic arbor immediately. Dendrogram analysis showed that in addition to distal, proximal apical dendrites also quickly reconfigured. We then focused on apical dendritic trunks and explored how proximal dendrites were rapidly altered. Compression instantly twisted the microtubules and deformed the membrane contour of dendritic trunks likely a result of the elastic nature of dendrites as immediate decompression restored it and stabilization of microtubules failed to block it. Subsequent adaptive remodeling restored plasmalemma and microtubules to normal appearance in 3 days likely via active mechanisms as taxol blocked the restoration of microtubules and in addition partly affected plasmalemmal reorganization which presumably engaged recycling of excess membrane. In short, the structural dynamics and the associated mechanisms that we revealed demonstrate how compression quickly altered the morphology of cortical output neurons and hence cortical functions consequently.
颅脑损伤和急性障碍常导致大脑皮质即刻受压，引发功能异常。我们采用大鼠硬脑膜下珠植入模型，研究急性压迫后的即刻变化。用细胞内染料填充受影响皮质锥体细胞的树突棘，进行三维重建分析。结果发现，急性压迫缩短了皮质第三和第五层的基底细胞的顶树突，但不影响基底树突，且即刻减少整个树突棘上的树突棘。树状图分析显示，除了远端的树突棘，近端的顶树突也迅速发生重排。然后，我们专注于顶树突干，探索近端树突是如何迅速改变的。急性压迫使微管扭曲，使树突干的细胞膜轮廓变形，这可能是由于树突的弹性所致，因为即时减压可使其恢复，而微管的稳定并不能阻止这种变形。随后的适应性重塑在 3 天内使质膜和微管恢复正常形态，可能是通过主动机制，因为紫杉醇可阻止微管的恢复，并且还部分影响质膜的重组，这可能涉及到过量膜的再循环。总之，我们揭示的结构动力学及其相关机制表明，急性压迫如何迅速改变皮质输出神经元的形态，从而影响皮质功能。
