Xu G Y, Huang L Y, Zhao Z Q
Shanghai Brain Research Institute, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China.
J Physiol. 2000 Oct 15;528 Pt 2(Pt 2):339-48. doi: 10.1111/j.1469-7793.2000.00339.x.
The effect of inflammation on the excitability and the level of substance P (SP) in cat mechanoreceptive C and Adelta dorsal root ganglion (DRG) neurons were studied in vivo using intracellular recording and immunocytochemical techniques. Following injections of carrageenan (Carg) into the cat hindpaw, the percentage of C neurons exhibiting spontaneous activity increased from 7.2 to 20.7% and the percentage of Adelta neurons increased from 6.9 to 18.6%. In contrast to most cells from normal cats, which fired regularly below 10 Hz, many cells from Carg-treated cats fired at higher frequencies or in bursts. Inflammation (Carg treatment) also depolarized membrane potentials, increased membrane input resistance, caused the disappearance of inward rectifying currents and lowered the mean current thresholds of tibial nerve-evoked responses in DRG neurons. With inflammation, the percentage of C or Adelta neurons responding to low threshold mechanoreceptive stimuli increased (C neurons: normal, 13%; inflamed, 41%; Adelta neurons: normal, 13 %; inflamed, 39 %), while the percentage of C or Adelta neurons responding to high threshold mechanoreceptive stimuli remained unchanged. Some receptive field (RF)-responsive cells were injected with Lucifer Yellow and their SP immunoreactivity was determined. Following Carg treatment, substantially higher percentages of RF-responsive cells were SP positive (C neurons: normal, 35.7%; inflamed, 60%; Adelta neurons: normal, 18.2%; inflamed, 66.7%). These combined increases in the excitability of DRG neurons and SP-containing RF-responsive neurons could lead to sensitization of sensory neurons, thus contributing to the development of hyperalgesia.
采用细胞内记录和免疫细胞化学技术，在体内研究了炎症对猫机械感受性C类和Aδ类背根神经节（DRG）神经元兴奋性及P物质（SP）水平的影响。向猫后爪注射角叉菜胶（Carg）后，出现自发活动的C类神经元百分比从7.2%增加到20.7%，Aδ类神经元百分比从6.9%增加到18.6%。与大多数正常猫的细胞在10Hz以下规律放电不同，许多来自Carg处理猫的细胞以更高频率或成簇放电。炎症（Carg处理）还使膜电位去极化，增加膜输入电阻，导致内向整流电流消失，并降低DRG神经元中胫神经诱发反应的平均电流阈值。炎症时，对低阈值机械感受性刺激有反应的C类或Aδ类神经元百分比增加（C类神经元：正常时为13%，炎症时为41%；Aδ类神经元：正常时为13%，炎症时为39%），而对高阈值机械感受性刺激有反应的C类或Aδ类神经元百分比保持不变。向一些感受野（RF）反应性细胞注射荧光黄并测定其SP免疫反应性。Carg处理后，RF反应性细胞中SP阳性的百分比显著更高（C类神经元：正常时为35.7%，炎症时为60%；Aδ类神经元：正常时为18.2%，炎症时为66.7%）。DRG神经元和含SP的RF反应性神经元兴奋性的这些联合增加可能导致感觉神经元致敏，从而促进痛觉过敏的发展。
