腰交感神经节射频热凝对糖尿病痛性周围神经病变大鼠的镇痛作用及对背根神经节TTX-R钠电流的影响

目的 评价射频热凝毁损腰交感神经节对糖尿病痛性周围神经病变大鼠的镇痛作用及对背根神经节（DRG）细胞上河豚毒素不敏感（TTX-R）钠通道电流的影响。方法 腹腔注射链尿佐菌素诱导大鼠糖尿病痛性周围神经病变模型，取造模成功的大鼠20只，随机分为糖尿病对照组（D组）及交感神经节射频热凝组（R组），每组10只，另取10只同月龄大鼠为正常对照组（C组），R组大鼠行右侧L3，4椎旁射频热凝毁损腰交感神经节。于射频热凝前、射频热凝后1、2周采用von Frey纤维丝测定缩爪反应阈值（PWT）;射频热凝后2周，急性分离小DRG细胞，采用全细胞膜片钳记录方法，在电压钳制下记录TTX-R钠通道电流。结果 与C组比较，射频热凝前D组和R组PWT降低（P〈0．01），射频热凝后1、2周，R组PWT低于C组（P〈0．05），高于D组（P〈0．05）;射频热凝后2周，与C组比较， D组、R组I-V曲线向左移，R组电流密度高于C组（P〈0．01），低于D组（P〈0．05），与C组比较，D组、R组半激活电压及半失活电压升高（P〈0．01），D组和R组之间差异无统计学意义（P〉0．05）。结论 腰交感神经节射频热凝可有效缓解糖尿病痛性周围神经病变大鼠的痛觉过敏，抑制小DRG细胞TTX-R钠通道电流可能是其发挥镇痛作用机制之一。

The effect of lumbar sympathetic ganglion radiofrequency thermocoagulation on hyperalgesia and TTX-R sodium currents in neurons of dorsal root ganglion in rats with painful diabetic neuropathy

Objective To evaluate the effect of lumbar sympathetic ganglion radiofrequency thermocoagulation on hyperalgesia and tetrodotoxin-resistant (TTR) sodium currents in neurons of dorsal root ganglion (DRG) of rats with painful diabetic neuropathy. Methods Twenty Sprague-Dawley rats with painful diabetic neuropathy induced by intraperitoneal injection of streptozotocine were randomly allocated to radiofrequency group (R group) and diabetic group (D group), meanwhile 10 healthy age-matched rats were selected as control group (C group). R group received L3,4 lumbar sympathetic ganglion radiofrequency thermocoagulation on the right side under X-ray guideline. Response of the hind paw to the mechanical stimulus was determined by von Frey filament to calculate paw withdraw threshold (PWT) before radiofrequency thermocoagulation, 1 w and 2 w later. TTX-R sodium current in small size neuron of DRG isolated from L4,3 lumbar region of the right side was recorded by the whole cell patch clamp configuration at 2 w after radiofrequency thermocoagulation. Results PWT in D group and R group was lower significantly before radiofrequency thermocoagulation than that in C group ( P < 0.01). PWT in R group was increased significantly at 1 w and 2 w after radiofrequency thermocoagulation as compared to that in D group( P < 0.05), but was still lower than that in C group( P < 0.05). The I-V curve of D and R group drifted left compared with that of C group. The TTX-R sodium currents density of small DRG neuron in R group was higher than in C group ( P < 0.01) and lower than in D group ( P < 0.05). As compared with those in C group, the potential of half activation or inactivation increased significantly in D and R group( P < 0.01) , but without significant differences between D and R group ( P > 0.05 ) . Conclusion Lumbar sympathetic ganglion radiofrequency thermocoagulation can alleviate hyperalgesia in rats with painful diabetic neuropathy, through inhibiting the TTX-R sodium channel currents in small DRG neurons.