Morphological plasticity induced in the phrenic nucleus following cervical cold block of descending respiratory drive
Morphological plasticity induced in the phrenic nucleus following cervical cold block of descending respiratory drive
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DOI：
10.1006/exnr.1997.6615
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发表时间：
1997-10-01
影响因子：
5.3
通讯作者：
Goshgarian, HG
中科院分区：
文献类型：
--
作者：
CastroMoure, F;Goshgarian, HG
同侧 C2 脊髓半切后数小时内，膈核中出现形态可塑性。可塑性与潜在呼吸通路（交叉膈通路）的暴露有关，这使得在称为交叉膈现象的反射期间因半切而麻痹的半膈得以恢复。这项研究测试了可塑性是否是由脊髓创伤的普遍影响引起的，还是由中断膈运动神经元的主要下行呼吸驱动的更具体的影响引起的。对脊髓第二颈段 (C2) 下降球脊髓呼吸驱动的单侧可逆冷阻滞后 4 小时处死的四只 Sprague-Dawley 大鼠 (200-250 g) 进行膈核神经纤维的电子显微镜定量形态分析。将四只假手术对照动物的数据与实验组的数据进行比较。与对照组相比，冷块动物中记录了以下形态学变化：（1）多个突触数量显着增加（即，具有在同一截面平面中接触两个或多个突触后轮廓的突触活动区的末端），（2）树突并置的数量显着增加，以及（3）对称和不对称突触活动区的长度显着增加。上述变化与 C2 半切后膈核引起的变化相似。因此，我们得出的结论是，脊髓损伤并不是膈核中这种形态可塑性的必要条件，而是引起的变化是活动依赖性的，并且可能是由于球脊髓呼吸驱动膈核的下降而中断引起的。 (C) 1997 年学术出版社。
Morphological plasticity occurs in the phrenic nucleus within hours following an ipsilateral C2 spinal cord hemisection. The plasticity has been associated with the unmasking of a latent respiratory pathway (the crossed phrenic pathway) which allows recovery of the hemidiaphragm paralyzed by the hemisection during a reflex known as the crossed phrenic phenomenon. This study tests if the plasticity is induced by the generalized effects of spinal cord trauma or the more specific effect of interrupting the main descending respiratory drive to phrenic motoneurons. Electron microscopic quantitative morphometric analysis of the phrenic nucleus neuropil was carried out on four Sprague-Dawley rats (200-250 g) sacrificed 4 h following unilateral reversible cold block of the descending bulbospinal respiratory drive at the second cervical segment of the spinal cord (C2). The data from four sham-operated control animals were compared with those of the experimental group. The following morphological alterations were documented in cold block animals compared to controls: (1) a significant increase in the number of multiple synapses (i.e., terminals with synaptic active zones contacting two or more postsynaptic profiles in the same plane of section), (2) a significant increase in the number of dendrodendritic appositions, and (3) a significant increase in the length of symmetric and asymmetric synaptic active zones. The above changes are similar to the changes induced in the phrenic nucleus following C2 hemisection. We conclude therefore, that injury to the spinal cord is not a requirement for this type of morphological plasticity in the phrenic nucleus, but rather the induced changes are activity-dependent and are likely caused by the interruption of the descending bulbospinal respiratory drive to the phrenic nucleus. (C) 1997 Academic Press.