Specificity of initial synaptic contacts made on guinea‐pig superior cervical ganglion cells during regeneration of the cervical sympathetic trunk.
Specificity of initial synaptic contacts made on guinea‐pig superior cervical ganglion cells during regeneration of the cervical sympathetic trunk.
复制标题
颈交感干再生过程中豚鼠颈上神经节细胞初始突触接触的特异性。
DOI：
10.1113/jphysiol.1978.sp012408
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
D. Purves
中科院分区：
文献类型：
--
作者：
A. Njå;D. Purves
1.在节前神经中断后，在较长的时间间隔内与颈上神经节中的神经元形成基本上适当的突触连接。在本研究中，我们通过观察体内对腹根刺激的终末器官反应，以及在分离制剂中记录腹根刺激期间神经节细胞的细胞内记录，评估了重新神经支配早期阶段连接的准确性。 2. 冷冻颈交感干后 15-30 天，通过刺激第一和第四胸腹根（T1 和 T4）引起适当但较弱的终末器官反应。 3. 体外刺激腹侧根 C8-T7 期间神经节细胞的细胞内记录表明，突触接触在冷冻节前神经后 8-11 天首次重新建立。神经损伤后约 3 个月内，重新受神经支配的细胞比例以及单个神经元的神经支配强度迅速增加，但此后几乎没有变化。即使在 6 个月后，神经支配仍然弱于正常。 4.再生早期细胞内记录的节段神经支配模式与正常相似，但比正常更受限制。即使在节前神经中断后 13‐‐19 天，由多个脊髓节段重新神经支配的神经元往往会受到脊髓节段的连续子集的支配，这些脊髓节段对神经节有神经支配。从不连续节段子集接受神经支配的神经元在早期和晚期或重新神经支配的发生率大致相同。 5. 在整个神经再生过程中，重新受神经支配的神经元倾向于接收来自特定脊髓水平的轴突的主导突触输入，正常细胞也是如此，相邻节段贡献的突触影响随着与主导节段的距离而减弱。 6. 这些实验的结果反对最初形成不精确的联系，随后保留适当的联系并失去不适当的联系。相反，我们的研究结果表明，神经节细胞的重新神经支配是通过突触连接的逐渐积累而进行的，这些连接从一开始就是适当的。
1. Largely appropriate synaptic connexions are formed with neurones in the superior cervical ganglion at long intervals after interruption of the preganglionic nerve. In the present study we have assessed the accuracy of connexions during the early stages of re‐innervation by observing end‐organ responses to ventral root stimulation in vivo, and by recording intracellularly from ganglion cells during ventral root stimulation in isolated preparations. 2. Appropriate, but weak, end‐organ responses were elicited by stimulation of the first and fourth thoracic ventral roots (T1 and T4) 15‐‐30 days after freezing the cervical sympathetic trunk. 3. Intracellular recordings from ganglion cells during stimulation of the ventral roots C8‐‐T7 in vitro showed that synaptic contacts are first re‐established 8‐‐11 days after freezing the preganglionic nerve. The proportion of re‐innervated cells, and the strength of innervation of individual neurones, increased rapidly for up to about 3 months after nerve injury, but showed little change thereafter. Innervation remained weaker than normal even after 6 months. 4. Patterns of segmental innervation recorded intracellularly during the early stages of regeneration were similar to, but more restricted than normal. Even 13‐‐19 days after interruption of the preganglionic nerve, neurones re‐innervated by more than one spinal cord segment tended to be innervated by a contiguous subset of the spinal segments which contribute innervation to the ganglion. The incidence of neurones receiving innervation from a discontinuous segmental subset was about the same at early and late stages or re‐innervation. 5. Throughout the course of nerve regeneration, re‐innervated neurones tended to receive dominant synaptic input from axons arising at a particular spinal level, as do normal cells, with adjacent segments contributing a synaptic influence that diminished as a function of distance from the dominant segment. 6. The results of these experiments argue against the initial formation of imprecise connexions with subsequent retention of appropriate contacts and a loss of inappropriate ones. Rather our findings suggest that the re‐innervation of ganglion cells proceeds by a gradual accumulation of synaptic connexions which are, from the outset, appropriate.