Ziemann U, Lönnecker S, Steinhoff B J, Paulus W
Department of Clinical Neurophysiology, University of Göttingen, Germany.
Ann Neurol. 1996 Sep;40(3):367-78. doi: 10.1002/ana.410400306.
The effect of a single oral dose of various antiepileptic drugs on the excitability of the motor system was studied in healthy volunteers by means of transcranial magnetic stimulation. Motor threshold, duration of the cortical silent period, and intracortical excitability after double-shock transcranial stimulation were tested before and at defined intervals after drug intake. Antiepileptic drugs that support the action of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the neocortex (vigabatrin, baclofen) reduced intracortical excitability but had no effect on motor threshold. Gabapentin, whose mechanism of action has not yet been unequivocally identified, showed a similar profile. By contrast, sodium and calcium channel blockers without considerable neurotransmitter properties (carbamazepine, lamotrigine, losigamone) elevated motor threshold but did not change intracortical excitability. The cortical silent period was lengthened by gabapentin and carbamazepine. Changes in peripheral motor excitability (maximum M wave, peripheral silent period) were not observed. We conclude that the changes in intracortical excitability are caused by GABA-controlled interneuronal circuits in the motor cortex while changes in motor threshold are dependent on ion channel conductivity and may reflect membrane excitability. Transcranial magnetic stimulation may be a promising noninvasive approach to study the selective effects of antiepileptic drugs on brain function.
通过经颅磁刺激，在健康志愿者中研究了单次口服各种抗癫痫药物对运动系统兴奋性的影响。在服药前及服药后设定的时间间隔，测试运动阈值、皮质静息期时长以及双脉冲经颅刺激后的皮质内兴奋性。在新皮质中增强抑制性神经递质γ-氨基丁酸（GABA）作用的抗癫痫药物（氨己烯酸、巴氯芬）降低了皮质内兴奋性，但对运动阈值无影响。作用机制尚未明确的加巴喷丁表现出类似的情况。相比之下，没有显著神经递质特性的钠通道和钙通道阻滞剂（卡马西平、拉莫三嗪、洛西加莫）提高了运动阈值，但未改变皮质内兴奋性。加巴喷丁和卡马西平延长了皮质静息期。未观察到外周运动兴奋性（最大M波、外周静息期）的变化。我们得出结论，皮质内兴奋性的变化是由运动皮质中GABA控制的中间神经元回路引起的，而运动阈值的变化取决于离子通道传导性，可能反映膜兴奋性。经颅磁刺激可能是一种很有前景的非侵入性方法，用于研究抗癫痫药物对脑功能的选择性作用。
