School of Dentistry, Brain Korea 21, Brain Science and Engineering Institute, Kyungpook National University, Daegu 700-412, Korea.
Korean J Physiol Pharmacol. 2009 Oct;13(5):379-83. doi: 10.4196/kjpp.2009.13.5.379. Epub 2009 Oct 31.
Nitric oxide (NO), a diffusible gas, is produced in the central nervous system, including the spinal cord dorsal horn and the trigeminal nucleus, the first central areas processing nociceptive information from periphery. In the spinal cord, it has been demonstrated that NO acts as pronociceptive or antinociceptive mediators, apparently in a concentration-dependent manner. However, the central role of NO in the trigeminal nucleus remains uncertain in support of processing the orofacial nociception. Thus, we here investigated the central role of NO in formalin (3%)-induced orofacial pain in rats by administering membrane-permeable or -impermeable inhibitors, relating to the NO signaling pathways, into intracisternal space. The intracisternal pretreatments with the NO synthase inhibitor L-NAME, the NO-sensitive guanylate cyclase inhibitor ODQ, and the protein kinase C inhibitor GF109203X, all of which are permeable to the cell membrane, significantly reduced the formalin-induced pain, whereas the membrane-impermeable NO scavenger PTIO significantly enhanced it, compared to vehicle controls. These data suggest that an overall effect of NO production in the trigeminal nucleus is pronociceptive, but NO extracellularly diffused out of its producing neurons would have an antinociceptive action.
一氧化氮（NO）是一种可扩散的气体，在中枢神经系统中产生，包括脊髓背角和三叉神经核，这是第一个处理来自外周的伤害性信息的中枢区域。在脊髓中，已经证明 NO 作为伤害性感受的促进或抑制介质，显然是一种浓度依赖性的方式。然而，NO 在三叉神经核中的中枢作用在支持处理口面部伤害性感受方面仍然不确定。因此，我们通过向蛛网膜下腔给予可透过或不可透过细胞膜的抑制剂，研究了 NO 在 3%福尔马林诱导的大鼠口面部疼痛中的中枢作用，这些抑制剂与 NO 信号通路有关。NO 合酶抑制剂 L-NAME、NO 敏感鸟苷酸环化酶抑制剂 ODQ 和蛋白激酶 C 抑制剂 GF109203X 的蛛网膜下腔预处理均显著减少了福尔马林诱导的疼痛，而不可透过细胞膜的 NO 清除剂 PTIO 则显著增强了疼痛，与载体对照组相比。这些数据表明，三叉神经核中 NO 产生的总体效应是伤害性感受促进的，但 NO 从其产生神经元中外泄会产生镇痛作用。
