Heterogeneous Spine Loss in Layer 5 Cortical Neurons after Spinal Cord Injury
Heterogeneous Spine Loss in Layer 5 Cortical Neurons after Spinal Cord Injury
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DOI：
10.1093/cercor/bhr191
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发表时间：
2012-06-01
期刊：
影响因子：
3.7
通讯作者：
Schwab, Martin E.
中科院分区：
文献类型：
--
作者：
Ghosh, Arko;Peduzzi, Stefano;Schwab, Martin E.
大面积胸椎脊髓损伤使后肢感觉运动皮层与目标腰椎脊髓分离。腋切皮层神经元突触结构的命运尚未得到很好的研究。在5层神经元亚群中表达黄色荧光蛋白的成年小鼠，我们在损伤后3、7和21天评估了轴切皮质脊髓神经元上的棘密度。早在损伤后3天，离躯体近端的树突节段（第5层）脊柱密度下降，远早于躯体萎缩的发生。在远端节段（第2/3层），脊柱丢失较近端节段缓慢且较轻。脑干皮质脊髓轴突的轴突切开术（锥体切开术）引起了脊柱密度的相应降低，这表明这种损失并不局限于胸椎脊髓的轴突切除的神经元。令人惊讶的是，在两种形式的损伤中，假定未切开的第5层神经元的脊柱密度也降低了。脊柱丢失可能反映了轴切开术后皮层回路的快速重排，例如，HL皮质神经元与不再提供有用信息的突触输入断开连接。
A large thoracic spinal cord injury disconnects the hindlimb (HL) sensory-motor cortex from its target, the lumbar spinal cord. The fate of the synaptic structures of the axotomized cortical neurons is not well studied. We evaluated the density of spines on axotomized corticospinal neurons at 3, 7, and 21 days after the injury in adult mice expressing yellow fluorescence protein in a subset of layer 5 neurons. Spine density of the dendritic segment proximal to the soma (in layer 5) declined as early as 3 days after injury, far preceding the onset of somatic atrophy. In the distal segment (in layer 2/3), spine loss was slower and less severe than in the proximal segment. Axotomy of corticospinal axons in the brainstem (pyramidotomy) induced a comparable reduction of spine density, demonstrating that the loss is not restricted to the neurons axotomized in the thoracic spinal cord. Surprisingly, in both forms of injury, the spine density of putative non-axotomized layer 5 neurons was reduced as well. The spine loss may reflect fast rearrangements of cortical circuits after axotomy, for example, by a disconnection of HL cortical neurons from synaptic inputs that no longer provide useful information.