Somers David L, Clemente F Richard
Department of Physical Therapy, John G. Rangos Sr. School of Health Sciences, Duquesne University, Pittsburgh, PA 15282-0011, USA.
Arch Phys Med Rehabil. 2003 Nov;84(11):1575-83. doi: 10.1053/s0003-9993(03)00290-9.
To examine the relation between axon terminal neurotransmitter content in the dorsal horn and allodynia in neuropathic rats treated with high-frequency transcutaneous electric nerve stimulation (TENS).
A completely randomized experimental design. Two groups of rats received a chronic constriction injury to the right sciatic nerve, and 2 groups did not. The rats were either treated or not treated with TENS.
Research laboratory.
Adult male Sprague-Dawley rats (150-165g).
TENS was delivered daily for 1 hour to the chronic constriction injury rats or to the uninjured rats through self-adhesive electrodes applied to the skin innervated by the right dorsal rami of lumbar spinal nerves 1 to 6.
Thermal and mechanical pain thresholds were assessed bilaterally in the hind paws of all rats twice before the chronic constriction injury surgery (baseline) and then 12 days after the surgery. An analogous time frame of assessment was used for rats that did not have chronic constriction injury surgery. Thermal and mechanical allodynia were expressed as difference scores between the pain thresholds of the right and left hind paws. These values were normalized to differences that existed between the 2 paws at baseline. The amino acid content of dorsal horn axon terminals was assessed bilaterally with high-pressure liquid chromatography, and values were normalized to wet weight.
The mean level of thermal and mechanical allodynia did not differ between the TENS-treated and untreated rats with chronic constriction injury. However, there was a significant relation between the dorsal horn, axon terminal content of glutamate (adjusted R(2)=.45, P<.01) and glycine (adjusted R(2)=.51, P<.005) and the magnitude of mechanical allodynia present in TENS-treated chronic constriction injury rats, but not in any other group. As axon terminal glutamate and glycine decreased in the right dorsal horn and increased in the left, mechanical allodynia was reduced or absent. When this trend was reversed, mechanical allodynia was more severe. Daily TENS also reduced the mean axon terminal content of aspartate, glutamate, and glycine bilaterally in the chronic constriction injury rats from the level observed in untreated neuropathic rats (P<.05).
The variability in responsiveness of mechanical allodynia to daily TENS treatment in neuropathic rats is related to the axon terminal content of glutamate and glycine in the dorsal horn. These findings may help explain a similar variability in humans when TENS is used to treat neuropathic pain.
研究高频经皮电刺激（TENS）治疗的神经病理性大鼠背角轴突终末神经递质含量与异常性疼痛之间的关系。
完全随机实验设计。两组大鼠右侧坐骨神经接受慢性压迫损伤，另两组未接受。大鼠接受或未接受TENS治疗。
研究实验室。
成年雄性Sprague-Dawley大鼠（150 - 165克）。
通过贴于由腰1至腰6右侧背根神经支配的皮肤的自粘电极，每天对慢性压迫损伤大鼠或未损伤大鼠进行1小时的TENS治疗。
在慢性压迫损伤手术前（基线）及术后12天，对所有大鼠双侧后爪的热痛阈和机械痛阈进行两次评估。对未进行慢性压迫损伤手术的大鼠采用类似的评估时间框架。热异常性疼痛和机械异常性疼痛用右后爪和左后爪痛阈的差值表示。这些值根据基线时两爪之间存在的差异进行标准化。用高压液相色谱法双侧评估背角轴突终末的氨基酸含量，其值根据湿重进行标准化。
接受TENS治疗和未接受TENS治疗的慢性压迫损伤大鼠之间，热异常性疼痛和机械异常性疼痛的平均水平无差异。然而，在接受TENS治疗的慢性压迫损伤大鼠中，背角轴突终末谷氨酸含量（调整后R² = 0.45，P < 0.01）和甘氨酸含量（调整后R² = 0.51，P < 0.005）与机械异常性疼痛的程度之间存在显著关系，而在其他组中未观察到这种关系。随着右侧背角轴突终末谷氨酸和甘氨酸含量减少而左侧增加，机械异常性疼痛减轻或消失。当这种趋势逆转时，机械异常性疼痛更严重。每天进行TENS治疗还使慢性压迫损伤大鼠双侧轴突终末天冬氨酸、谷氨酸和甘氨酸的平均含量较未治疗的神经病理性大鼠所观察到的水平降低（P < 0.
