A study on the role of neurotrophines in trigeminal neuropathy and sensory abnormality

采用麻醉大鼠（TNP组）经卵圆孔注射医用硅胶致三叉神经节慢性压迫损伤。另外7只大鼠（SHM组）在不注射硅胶的情况下进行与TNP组相同的解剖。7只大鼠接受NGF （NGF组），7只大鼠接受BDNF （BDNF组）。TNP组和NGF组术后第4天出现热痛觉过敏，术后第7天出现机械异常性痛。然而，SHM组和BDNF组在时间过程中没有表现出任何显著的阈值下降。这些结果表明，NGF本身诱导中枢致敏，而BDNF不具有这种作用。在接下来的研究中，大鼠从注射NGF前3天开始，分别给予200 mg/kg/天或2000 mg/kg/天的i.p GSH （NGF-200组：n-7， NGF-2000组：n=7）和4 mg/kg/天的DEM代替GSH （NGF-DEM组：n=7）。各组的对照组采用假治疗替代NGF注射（SHM-2000和SHM-DEM组）。NGF-200组和NGF-DEM组在术后第4天和第7天分别显示出辐射热刺激的头部退缩潜伏期减少。相比之下，NGF-2000、SHM-2000和SHM-DEM组没有表现出任何明显的热、机械痛觉过敏或异常性疼痛的行为。这些结果表明，谷胱甘肽通过抑制NGF诱导的三叉神经核细胞的超敏反应来预防痛觉过敏。

A chronic compression injury to the trigeminal ganglion by an injection of medical silicone via the foramen ovale was induced on seven anesthetized rats (TNP group). The same dissection to the TNP group without injecting silicone was performed on another seven rats (SHM group). Seven rats received cysternal injection of NGF (NGF group) and another seven rats received BDNF (BDNF group). The TNP group and the NGF group showed heat hyperalgesia from fourth post-operative day and mechanical allodynia from seventh post-operative day. However, the SHM and the BDNF groups did not show any significant decrease of thresholds during the time course. These results showed that NGF induces central sensitization by itself and BDNF doesn't have such an effect. In the next study, rats received 200 mg/kg/day or 2000 mg/kg/day of i.p. GSH (NGF-200 group : n-7 and NGF-2000 group : n=7) and 4 mg/kg/day of DEM instead of GSH (NGF-DEM group : n=7) from three days before the NGF injection. Control groups to these groups were prepared by performing sham treatment instead of the NGF injection (SHM-2000 and SHM-DEM groups). NGF-200 and NGF-DEM groups showed decrease of head withdrawal latency from radiant heat stimulation from fourth and seventh post-operative days, respectively. In contrast, NGF-2000, SHM-2000 and SHM-DEM groups did not show any significant behaviors suggesting heat- and mechano-hyperalgesia or allodynia. These results revealed that GSH prevented hyperalgesia by suppressing hypersensitization of the trigeminal nucleus cells that is induced by NGF.