Saito Kimiko, Hitomi Suzuro, Suzuki Ikuko, Masuda Yuji, Kitagawa Junichi, Tsuboi Yoshiyuki, Kondo Masahiro, Sessle Barry J, Iwata Koichi
Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, Japan.
J Neurophysiol. 2008 May;99(5):2251-63. doi: 10.1152/jn.00794.2007. Epub 2008 Mar 12.
Modulation of trigeminal spinal subnucleus caudalis neuronal activity following regeneration of transected inferior alveolar nerve in rats. To clarify the neuronal mechanisms of abnormal pain in the face innervated by the regenerated inferior alveolar nerve (IAN), nocifensive behavior, trigeminal ganglion neuronal labeling following Fluorogold (FG) injection into the mental skin, and trigeminal spinal subnucleus caudalis (Vc) neuronal properties were examined in rats with IAN transection. The mechanical escape threshold was significantly higher at 3 days and lower at 14 days after IAN transection, whereas head withdrawal latency to heat was significantly longer at 3, 14, and 60 days after IAN transection. The number of FG-labeled ganglion neurons was significantly reduced at 3 days after IAN transection but increased at 14 and 60 days. The number of wide dynamic range (WDR) neurons with background (BG) activity was significantly higher at 14 and 60 days after IAN transection compared with naïve rats, and the number of WDR and low-threshold mechanoreceptive (LTM) neurons with irregularly bursting BG activity was increased at these two time points. Mechanically evoked responses were significantly larger in WDR and LTM neurons 14 days after IAN transection compared with naïve rats. Heat- and cold-evoked responses in WDR neurons were significantly lower at 14 days after transection compared with naïve rats. Mechanoreceptive fields were also significantly larger in WDR and LTM neurons at 14 and 60 days after IAN transection. These findings suggest that these alterations may be involved in the development of mechanical allodynia in the cutaneous region innervated by the regenerated IAN.
大鼠下牙槽神经横断后再生过程中三叉神经脊束尾侧亚核神经元活动的调节。为阐明再生的下牙槽神经（IAN）支配的面部异常疼痛的神经元机制，对IAN横断的大鼠进行了伤害性防御行为、向颏部皮肤注射荧光金（FG）后三叉神经节神经元标记以及三叉神经脊束尾侧亚核（Vc）神经元特性的检测。IAN横断后3天机械逃避阈值显著升高，14天降低，而对热刺激的头部撤离潜伏期在IAN横断后3天、14天和60天显著延长。IAN横断后3天FG标记的神经节神经元数量显著减少，但在14天和60天增加。与正常大鼠相比，IAN横断后14天和60天具有背景（BG）活动的广动力范围（WDR）神经元数量显著增加，且在这两个时间点具有不规则爆发性BG活动的WDR和低阈值机械感受性（LTM）神经元数量增加。与正常大鼠相比，IAN横断后14天WDR和LTM神经元的机械诱发反应显著增大。横断后14天WDR神经元对热和冷刺激的反应与正常大鼠相比显著降低。IAN横断后14天和60天，WDR和LTM神经元的机械感受野也显著增大。这些发现表明，这些改变可能参与了再生IAN支配的皮肤区域机械性异常性疼痛的发生。
