Fukushima Nanae, Yokouchi Kumiko, Kawagishi Kyutaro, Kakegawa Akira, Ezawa Naoki, Moriizumi Tetsuji
Department of Anatomy, Shinshu University School of Medicine, Matsumoto, Nagano, Japan.
J Neurosci Res. 2007 Aug 15;85(11):2518-26. doi: 10.1002/jnr.21383.
The adaptive movement of the tongue after unilateral lesion of the hypoglossal (XII) nerve during the early postnatal days is essential for recovery of milk intake. The present study investigated the basic mechanisms underlying such adaptation, focusing on the neural plasticity that allows effective suckling. After resection of the ipsilateral XII nerve on P1, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlolate (DiI), a postmortem neuronal tracer, was applied to the contralateral uninjured XII nerve on P4 and P7. DiI-labeled fibers were traced successfully within the tongue and showed gradually increased extension over the XII nerve-injured side in the central core portion of the denervated tongue between P4 and P7. Systematic neuroanatomic experiments showed that contralateral axonal sprouting occurred as early as 1 day after nerve injury (P2), and that such axonal sprouting occurred exclusively from the medial branch of the XII nerve responsible for tongue protrusion, an essential movement for suckling. These findings provide direct evidence of functional neural plasticity that allows effective suckling in XII nerve-injured newborns with suckling disturbance.
出生后早期舌下神经（XII）单侧损伤后舌头的适应性运动对于恢复乳汁摄入至关重要。本研究调查了这种适应性的基本机制，重点关注允许有效吸吮的神经可塑性。在出生后第1天（P1）切除同侧XII神经后，在出生后第4天（P4）和第7天（P7）将一种死后神经元示踪剂1,1'-二辛基-3,3,3',3'-四甲基吲哚羰花青高氯酸盐（DiI）应用于对侧未受损的XII神经。DiI标记的纤维在舌内成功追踪到，并显示在P4和P7之间去神经支配舌的中央核心部分，在XII神经损伤侧的延伸逐渐增加。系统的神经解剖学实验表明，对侧轴突发芽早在神经损伤后1天（P2）就发生了，并且这种轴突发芽仅发生于负责伸舌的XII神经内侧支，伸舌是吸吮的一项基本运动。这些发现为功能性神经可塑性提供了直接证据，这种可塑性使得有吸吮障碍的XII神经损伤新生儿能够进行有效吸吮。
