Takeda M, Tanimoto T, Ikeda M, Nishikawa T, Kawanishi N, Mohri M, Shimizu T, Matsumoto S
Department of Physiology, School of Dentistry at Tokyo, Nippon Dental University, Japan.
Arch Histol Cytol. 1999 May;62(2):165-70. doi: 10.1679/aohc.62.165.
The present study aims to test the hypothesis that hyperbaric exposure inhibits nociceptive processing in the trigeminal spinal nucleus caudalis and C1 spinal neurons. We investigated the c-Fos-like immunoreactivity of the brainstem and upper cervical spinal cord (C1 region) following an injection of mustard oil (15 microliters of 20%) into the nasal mucosa of pentobarbital anesthetized rats after exposure to hyperbaric (2-atmospheres, 1 h) and normobaric pressures. After the hyperbaric exposure, the mean number of Fos-immunoreactive neurons in the ipsilateral laminae I-II and III-IV of the trigeminal spinal nucleus caudalis were significantly lower than those in the normobaric condition. Similarly, the mean number of c-Fos positive neurons in the superficial layer (I-II) of the ipsilateral C1 segment were significantly reduced as compared with that in the normobaric condition. When treated with the vehicle alone, no significant difference was detected in the numbers of c-Fos positive neurons in the trigeminal spinal nucleus caudalis and C1 regions between hyperbaric and normobaric conditions. These results suggest that hyperbaric exposure may attenuate nociceptive signals from the area innervated by the trigeminal nerves at the level of both the trigeminal spinal nucleus caudalis and C1 dorsal horn.
本研究旨在验证高压暴露抑制三叉神经脊束核尾侧亚核和C1脊髓神经元伤害性处理的假说。我们在戊巴比妥麻醉的大鼠鼻腔黏膜注射芥子油（20%的15微升）后，分别在高压（2个大气压，1小时）和常压条件下，研究脑干和颈上段脊髓（C1区）的c-Fos样免疫反应性。高压暴露后，三叉神经脊束核尾侧亚核同侧I-II层和III-IV层Fos免疫反应性神经元的平均数量显著低于常压条件下。同样，同侧C1节段表层（I-II）c-Fos阳性神经元的平均数量与常压条件相比也显著减少。单独使用溶剂处理时，高压和常压条件下三叉神经脊束核尾侧亚核和C1区c-Fos阳性神经元数量未检测到显著差异。这些结果表明，高压暴露可能在三叉神经脊束核尾侧亚核和C1背角水平减弱来自三叉神经支配区域的伤害性信号。
