Ainsworth Lisa, Budelier Kendra, Clinesmith Monica, Fiedler Abby, Landstrom Rachel, Leeper B J, Moeller LeAnn, Mutch Sarah, O'Dell Kim, Ross Jaclyn, Radhakrishnan Rajan, Sluka Kathleen A
Graduate Program of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa, IA, USA Pain Research Program, University of Iowa, Iowa, IA, USA Neuroscience Graduate Program, University of Iowa, Iowa, IA, USA.
Pain. 2006 Jan;120(1-2):182-187. doi: 10.1016/j.pain.2005.10.030. Epub 2005 Dec 19.
Transcutaneous electrical nerve stimulation (TENS) reduces pain through central mechanisms involving spinal cord and brainstem sites. Since TENS acts through central mechanisms, we hypothesized that TENS will reduce chronic bilateral hyperalgesia produced by unilateral inflammation when applied either ipsilateral or contralateral to the site of muscle inflammation. Sprague-Dawley rats were injected with carrageenan in the left gastrocnemius muscle belly. Mechanical withdrawal threshold was tested bilaterally before and 2 weeks after carrageenan injection. After testing withdrawal thresholds at 2 weeks, rats received TENS treatment either ipsilateral or contralateral to the site of inflammation. In each of these groups, rats were randomized to control (no TENS), low frequency (4 Hz), or high frequency (100 Hz) TENS treatment. TENS was applied for 20 min at sensory intensity under light halothane anesthesia. Mechanical withdrawal thresholds were re-assessed after TENS or 'no TENS' treatment. Unilateral injection of carrageenan to the gastrocnemius muscle significantly reduced the mechanical withdrawal threshold (mechanical hyperalgesia) bilaterally 2 weeks later. Either low or high frequency TENS applied to the gastrocnemius muscle ipsilateral to the site of inflammation significantly reversed mechanical hyperalgesia, both ipsilateral and contralateral to the site of inflammation. Low or high frequency TENS applied to the gastrocnemius muscle contralateral to the site of inflammation also significantly reduced mechanical hyperalgesia, both ipsilateral and contralateral to the site of inflammation. Since ipsilateral or contralateral TENS treatments were effective in reducing chronic bilateral hyperalgesia in this animal model, we suggest that TENS act through modulating descending influences from supraspinal sites such as rostral ventromedial medulla (RVM).
经皮电刺激神经疗法（TENS）通过涉及脊髓和脑干部位的中枢机制减轻疼痛。由于TENS通过中枢机制起作用，我们推测，当TENS应用于肌肉炎症部位的同侧或对侧时，它将减轻由单侧炎症产生的慢性双侧痛觉过敏。将角叉菜胶注射到Sprague-Dawley大鼠的左腓肠肌肌腹中。在注射角叉菜胶前和注射后2周，双侧测试机械性撤针阈值。在2周时测试撤针阈值后，大鼠接受在炎症部位同侧或对侧的TENS治疗。在这些组中的每一组，大鼠被随机分配到对照组（不进行TENS）、低频（4Hz）或高频（100Hz）TENS治疗。在轻度氟烷麻醉下以感觉强度施加TENS 20分钟。在TENS或“无TENS”治疗后重新评估机械性撤针阈值。向腓肠肌单侧注射角叉菜胶在2周后显著降低双侧的机械性撤针阈值（机械性痛觉过敏）。应用于炎症部位同侧腓肠肌的低频或高频TENS均显著逆转了炎症部位同侧和对侧的机械性痛觉过敏。应用于炎症部位对侧腓肠肌的低频或高频TENS也显著降低了炎症部位同侧和对侧的机械性痛觉过敏。由于同侧或对侧TENS治疗在该动物模型中有效减轻慢性双侧痛觉过敏，我们认为TENS通过调节来自延髓头端腹内侧（RVM）等脊髓上部位的下行影响而起作用。
