A型肉毒毒素对神经和肌肉影响的效价研究

Study on the effects of botulinum toxin A on muscle and nerve

目的:探讨新鲜和储存的A型肉毒毒素(BTXA)对神经及肌肉的影响,以期指导临床治疗。方法:将27只新西兰白兔随机分成9组,选择耳前肌为注射部位。第1组为对照组,余8组为注射组。各注射组接受BTXA的注射,大体观察各组实验动物右耳下垂的情况;并均于注射后第5天(早期)和第12周(晚期)取注射的肌肉神经行电镜观察。结果:大体观察结果:随储存时间的延长,兔耳下垂的时间越短。肌肉电镜观察结果:在注射后早期(第5天),新鲜及储存的BTXA对肌肉的影响无显著性差异;在注射后晚期(第12周),新鲜及储存1～2周的BTXA比较,两者造成的肌肉萎缩程度无显著性差异,但储存3周的BTXA造成的肌肉变性程度比储存1～2周的BTXA轻。神经电镜观察结果:BTXA注射后神经改变与上述肌肉改变同。结论:储存1～2周的BTXA与新鲜BTXA比较,两者效价基本相同,但储存3周的BTXA效价下降显著。并且,新鲜BTXA及储存1～2周的BTXA对神经肌肉的影响时间较储存3周的BTXA更持久。因此本实验建议临床上储存BTXA的时间不超过2周。

Objective The aim of the study was to compare the effects of fresh and stored botulinum toxin A on muscle and nerve, by means of which the clinical treatment can be instructed. Methods 27 New Zealand white rabbits were divided into 9 groups, and anterior auricular muscle was used for injections. Group 1 was used as the control group and the rest 8 groups were used as the injection groups. Each group received the injection of BTXA inspite of the control group. Each rabbit had weekly visual evaluation of the maximum erect static position of the right auricle. Muscles and motor nerves were harvested at 5 days （early period） and 12 weeks （late period） respectively after BTXA injection. Alterations in muscle and nerve ultrastructure were evaluated with electron microscopy. Results The visual evaluation results showed that there was an overall quicker trend to return to baseline the longer the BTXA was stored. Degeneration findings in muscle after botulinum toxin injection revealed no significant difference between freshly reconstituted and stored toxin in the early period （the fifth day）. When stored （for 1 and 2 weeks） toxin was used, atrophic changes in the muscle were the same as the fresh toxin at 12 weeks. Muscles of the group which was injected BTXA stored for 3 weeds had less severe degenerative findings than group which was injected with BTXA stored for 1 and 2 weeks muscles. On nerve evaluation, the changes on nerve ultrastructure shows similar degeneration as the muscle. Conclusion It seems that stored BTXA for 1 weeks and stored BTXA for 2 weeks has the same initial potency, but the duration of action significantly decreased when BTXA was stored for 3 weeks or more. Stored （for 1 and 2 weeks） and fresh BTXA are more durable than the stored BTXA for 3 weeks. Hence, we command that the time for the storage of BTXA should better be shorter than 2 weeks.