Rokugo Tomoyuki, Takeuchi Toshitsugu, Ito Hiromoto
Department of Orthopaedic Surgery, Nippon Medical School, Japan.
J Nippon Med Sch. 2002 Oct;69(5):428-33. doi: 10.1272/jnms.69.428.
The effects of pain stimulant and transcutaneous electrical nerve stimulation (TENS) on changes in substance P (SP) levels were investigated in the dorsal root ganglion (DRG) and dorsal horn of the spinal cord of Sprague-Dawley rats. The rats were divided into three groups: control, formalin stimulation and formalin+TENS. In all rats, the right sciatic nerve was attached to a hook electrode for recording, and the right lower leg was connected to a ring electrode. As a pain stimulant for the formalin stimulation group and formalin+TENS group, 50 microliter of a 5%formalin was injected into the right paw. At the same time, TENS (50Hz, 50V) for 5 minutes was applied via the ring electrode to the formalin+TENS group. After completing the stimulation, the components of the sciatic nerve, i. e. the DRG of the fourth to sixth lumbar spinal roots and a part of spinal cord, were removed. SP-like immunoreactivity (SP-LI) in the DRGs was quantified by the ELISA method. For the spinal cord, immunohistochemical staining for SP was carried out using an avidin-biotin immunoperoxidase method. Using an NIH image, the SP grains in the nerve ends, which were seen as dark brown stains on the Rexed laminae I and II in the dorsal horn of the spinal cord, were counted within a 450 micrometer (2) area. The results showed that SP-LI levels of both the DRG and the dorsal horn of the spinal cord in the formalin+TENS group were significantly reduced as compared with formalin stimulation group. Based on the fact that SP is a nociceptive neurotransmitter, the present study suggests that TENS reduces production of SP in the DRG, and shows analgesic effects by suppressing nociception via C-fiber in the peripheral nerves.
研究了疼痛刺激剂和经皮电刺激神经疗法（TENS）对Sprague-Dawley大鼠背根神经节（DRG）和脊髓背角中P物质（SP）水平变化的影响。将大鼠分为三组：对照组、福尔马林刺激组和福尔马林+TENS组。对所有大鼠，将右坐骨神经连接到钩状电极进行记录，右小腿连接到环形电极。作为福尔马林刺激组和福尔马林+TENS组的疼痛刺激剂，将50微升5%的福尔马林注射到右爪。同时，通过环形电极对福尔马林+TENS组施加5分钟的TENS（50Hz，50V）。刺激完成后，取出坐骨神经的组成部分，即第四至第六腰神经根的DRG和一部分脊髓。通过ELISA法对DRG中的SP样免疫反应性（SP-LI）进行定量。对于脊髓，采用抗生物素蛋白-生物素免疫过氧化物酶法对SP进行免疫组织化学染色。使用NIH图像，在脊髓背角Rexed板层I和II中被视为深棕色染色的神经末梢中的SP颗粒，在450平方微米的区域内进行计数。结果显示，与福尔马林刺激组相比，福尔马林+TENS组的DRG和脊髓背角中的SP-LI水平均显著降低。基于SP是一种伤害性神经递质这一事实，本研究表明TENS可减少DRG中SP的产生，并通过抑制外周神经中C纤维的伤害感受而发挥镇痛作用。
