Long-term reorganization of respiratory pathways after partial cervical spinal cord injury
Long-term reorganization of respiratory pathways after partial cervical spinal cord injury
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DOI：
10.1111/j.1460-9568.2008.06072.x
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发表时间：
2008-02-01
影响因子：
3.4
通讯作者：
Kastner, Anne
中科院分区：
文献类型：
--
作者：
Vinit, Stephane;Darlot, Fannie;Kastner, Anne
高位颈段脊髓损伤（SCI）中断了支配膈运动神经元的球脊髓呼吸通路，导致膈神经（PN）和膈肌失活。我们以前已经证明，同侧（ipsi）PN失活后，横向C2 SCI，但自发地部分重新激活后7天SCI。这种膈神经的激活依赖于对侧下行通路，位于外侧，穿过脊髓中线。我们在此分析了是否长期病变后的变化可能发生在呼吸网络。我们发现，与SCI后7天相比，3个月时同侧PN再激活更大，并且在急性对侧膈切开术（Phx）后增强，这也诱导了同侧膈的大量再激活（SCI后7天未检测到）。在SCI后3个月（与SCI后7天相比），ipsi PN活动仅受到ipsi Phx或gallamine治疗（一种烟碱神经肌肉阻滞剂）的中度影响，这表明它对ipsi感觉膈传入的依赖性较小。在额外的急性脊髓损伤后（C1）进行横向，ipsi PN活动被取消在大鼠脊髓损伤后7天，但持续在大鼠脊髓损伤后3个月。因此，这种活动依赖于新的功能下降通路位于内侧，而不是外侧。这些可能不涉及新招募的神经元的逆行标记显示，同侧膈运动神经元的神经支配的延髓呼吸神经元的数量相似后，短期和长期的损伤后的时间。这些结果表明，经过一段长时间的损伤后，膈神经的再激活是由脊髓呼吸通路的解剖功能重组加强。
High cervical spinal cord injury (SCI) interrupts bulbospinal respiratory pathways innervating phrenic motoneurons, and induces an inactivation of phrenic nerves (PN) and diaphragm. We have previously shown that the ipsilateral (ipsi) PN was inactivated following a lateral C2 SCI, but was spontaneously partially reactivated 7 days post-SCI. This phrenic reactivation depended on contralateral (contra) descending pathways, located laterally, that cross the spinal midline. We analysed here whether long-term post-lesional changes may occur in the respiratory network. We showed that ipsi PN reactivation was greater at 3 months compared with 7 days post-SCI, and that it was enhanced after acute contra phrenicotomy (Phx), which also induced a substantial reactivation of the ipsi diaphragm (not detected at 7 days post-SCI). At 3 months post-SCI (compared with 7 days post-SCI), ipsi PN activity was only moderately affected by ipsi Phx or by gallamine treatment, a nicotinic neuromuscular blocking agent, indicating that it was less dependent on ipsi sensory phrenic afferents. After an additional acute contra SCI (C1) performed laterally, ipsi PN activity was abolished in rats 7 days post-SCI, but persisted in rats 3 months post-SCI. This activity thus depended on new functional descending pathways located medially rather than laterally. These may not involve newly recruited neurons as retrograde labelling showed that ipsi phrenic motoneurons were innervated by a similar number of medullary respiratory neurons after a short and long post-lesional time. These results show that after a long post-lesional time, phrenic reactivation is reinforced by an anatomo-functional reorganization of spinal respiratory pathways.