A型肉毒毒素对脊髓α运动神经元活性的调节作用

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。

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

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 difference of modified Rivlin loxotic 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.