O'Hanlon G M, Lowrie M B
Department of Anatomy and Cell Biology, St Mary's Hospital Medical School, Imperial College, Norfolk Place, London W2 1PG, UK.
Eur J Neurosci. 1996 Jun;8(6):1072-7. doi: 10.1111/j.1460-9568.1996.tb01274.x.
Peripheral nerve crush during the early neonatal period results in the death of a large proportion of affected motoneurons and abnormal dendritic development in those which survive. The present study reports the effects of neonatal dorsal root section on motoneurons supplying the extensor digitorum longus muscle of the rat. This lesion did not result in motoneuron death, but did disrupt subsequent dendritic development. In cells retrogradely labelled with cholera toxin subunit B conjugated to horseradish peroxidase, there was little change in adult dendritic morphology in the transverse plane, where abnormalities associated with loss of efferent contact and cell death have been found. However, there was a caudal expansion of the dendritic field, an effect seen following nerve crush but not after blockade of neuromuscular transmission alone. The results show that disruption of dorsal root sensory inputs alone can affect the dendritic development of motoneurons but does not cause their death. In conjunction with our earlier findings, it is clear that both afferent and efferent connections are required for normal dendritic development, and disruption of either has a characteristic effect on survival and dendritic morphology.
新生儿早期的外周神经挤压会导致大部分受影响的运动神经元死亡，而存活下来的运动神经元则会出现异常的树突发育。本研究报告了新生大鼠背根切断对支配趾长伸肌的运动神经元的影响。这种损伤并未导致运动神经元死亡，但确实扰乱了随后的树突发育。在用与辣根过氧化物酶偶联的霍乱毒素B亚单位逆行标记的细胞中，在横切面上成年树突形态几乎没有变化，而在该横切面上已发现与传出联系丧失和细胞死亡相关的异常。然而，树突野出现了向尾侧扩展的现象，这种现象在神经挤压后可见，但仅在阻断神经肌肉传递后未见。结果表明，仅背根感觉输入的中断就能影响运动神经元的树突发育，但不会导致其死亡。结合我们早期的研究结果，很明显，正常的树突发育需要传入和传出连接，任何一方的中断都会对存活和树突形态产生特征性影响。
