A型肉毒毒素对脊髓α运动神经元活性的调节作用

Activity of α motor neuron of spinal cord modulated by botulinum toxin A

目的探索大鼠背根神经节A型肉毒毒素注射对脊髓前角α运动神经元活性及相关肌肉运动功能的影响作用。方法40只雄性Wistar大鼠,采用数字表法随机分为4组(每组10只):A组、B组、C组、D组。于实验前1天对各组大鼠进行H反射检测及运动功能评价,后以10%水合氯醛0.3 mL/kg腹腔注射进行麻醉,无菌条件下行左侧L4、L5、L6限制性椎板部分切除后暴露背根神经节。A组、B组分别以A型肉毒毒素背根神经节注射,C组注射等容积(6μL)0.9%氯化钠注射液,D组不干预为正常对照组。各组分别于注射后1,3,7,14 d进行H反射及运动功能评定。结果 (1)H反射测定:A型肉毒毒素注射后各观察时间点,A组大鼠左后肢H反射潜伏期、波幅较注射前均明显延长、降低(P<0.05,P<0.01);B、C、D 3组大鼠注射后各观察时间点与注射前比较H反射潜伏期及波幅差异均无统计学意义。A组大鼠A型肉毒毒素注射后各观察时间点H反射潜伏期及波幅较B、C、D组的相应观察时间点明显延长(P<0.05)和降低(P<0.01);A型肉毒毒素注射后各观察时间点B组与C组,B组与D组,C组与D组组间两两比较,H反射潜伏期及波幅差异无统计学意义(P>0.05)。(2)改良Rivlin斜板实验:A组大鼠,A型肉毒毒素注射后各观察时间点,斜板度数均较注射前为低(P<0.05);A型肉毒毒素注射后第7天,第14天,A组斜板度数显著低于B、C、D组(P<0.05,P<0.01,P<0.01);注射后不同时间点B组与C组,B组与D组,C组与D组斜板度数组间两两比较差异无统计学意义(P>0.05)。结论背根神经节A型肉毒毒素注射具有抑制脊髓反射环路,降低脊髓前角α运动神经元兴奋性的作用。

Objective To study the modulating effect of botulinum toxin A （BTX-A） on the α motor neurons in spinal cord anterior horn. Methods Forty Wistar rats were randomly divided into four groups： group A, group B, group C, and group D. All rats in each group were anesthetized with 10% chloraldurat （0.3 mL/kg）. Dorsal root ganglion（DRG） of L4, L5, L6 on the left were exposed following partial laminectomy under the condition of sterility. In Group A and group B, 7 U/kg, 4 U/kg of BTX-A was injected into DRG respectively. In Group C, DRG was injected with the same volume of physiological saline. Group D is the control group. Spinal reflex function and neuroethology were evaluated before and 1, 3, 7, 14 days after BTX-A administration. Results H reflex latency and amplitude of the left hind limb of the rats were longer（ P〈0.05 ） and lower（ P〈0.01 ） than that of before BTX-A injection in group A. There was also no significant difference of H reflex latency and amplitude in goup B, C, and D when compared before and after BTX-A injection. H reflex latency and amplitude at different time points after BTX-A injection in group A were longer and lower than those of group B, C and D（P〈0. 05, P〈0. 01 ） on 7 days and 14 days after BTX-A injection. There was no significant difference of H reflex latency and amplitude at different time points after BTX-A injection between goup B and C, goup B and D, group C and D（P〉0.05）. The degree of modified Rivlin loxotic plate test at different time points is lower when compared after and before BTX-A injection in group A（P〈0. 05 ）. The degree of modified Rivlin loxotic plate test in group A is lower than that of group B, C and D at different time points after BTX-A injection（ P〈0.05 ）. There was no significant differenee of modified Rivlin loxotie plate test degree between group B and C, group B and D, or group C and D （ P〉0.05 ） at different time points after BTX-A injection. Conclusion DRG injection of botulinum toxin type A may fundamentally block circuit of spinal and lower excitability of the α motor neurons in spinal cord anterior horn.