Hu J W, Woda A, Sessle B J
Faculty of Dentistry, University of Toronto, Canada.
Arch Oral Biol. 1999 Mar;44(3):287-93. doi: 10.1016/s0003-9969(98)00111-3.
Previous work has shown increased excitability of brainstem neurones in the trigeminal (V) subnucleus oralis following the deafferentation produced by tooth-pulp removal. The present study was designed to determine if the changes in oralis neuronal properties seen in cats 1-2 wk after the deafferentation could be blocked by local anaesthesia of the Vth nerve proximal to the sites of pulp injury just before the actual deafferentation. The response properties of neurones recorded in V subnucleus oralis were determined in anaesthetized cats. One or two weeks before neuronal recording, the pulps of the posterior mandibular teeth were removed under local mandibular anaesthesia in one group of cats (group A) and without local anaesthesia in a second group (group B); a third group (group C) had no pulp removal but received local anaesthesia. Consistent with the earlier data, there was a significantly increased incidence of neurones having an enlarged mechanoreceptive field, spontaneous activity and habituating tap sensitivity in group B compared to group C, but no significant differences were found between the two deafferented groups (A and B). As local anaesthesia did not prevent the development of pulp deafferentation-induced changes in the oralis neurones, it is unlikely that an afferent barrage of impulses induced by the deafferentation procedure was responsible for the neuroplastic changes that subsequently developed in the V subnucleus oralis.
先前的研究表明，牙髓摘除导致传入神经阻滞之后，三叉神经（V）口部亚核中的脑干神经元兴奋性增加。本研究旨在确定在实际传入神经阻滞之前，对牙髓损伤部位近端的V神经进行局部麻醉，是否能够阻止在传入神经阻滞后1-2周的猫中观察到的口部神经元特性变化。在麻醉的猫中测定口部亚核中记录的神经元的反应特性。在神经元记录前一或两周，一组猫（A组）在下颌局部麻醉下摘除下颌后牙的牙髓，第二组（B组）在没有局部麻醉的情况下进行；第三组（C组）未摘除牙髓，但接受局部麻醉。与早期数据一致，与C组相比，B组中具有扩大的机械感受野、自发活动和习惯性轻叩敏感性的神经元发生率显著增加，但在两个传入神经阻滞组（A组和B组）之间未发现显著差异。由于局部麻醉不能阻止牙髓传入神经阻滞引起的口部神经元变化的发展，因此由传入神经阻滞程序诱导的传入冲动 barrage 不太可能是随后在三叉神经口部亚核中发生的神经可塑性变化的原因。
