Silberstein E, Schleifstein-Attias D, Grossman Y
Department of Physiology, Corob Center for Medical Research, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Brain Res. 1992 Jul 24;586(2):273-8. doi: 10.1016/0006-8993(92)91636-s.
The frequency-dependent effect of various anticonvulsant drugs on the conduction in central axons was studied in the corpus callosum of rat and guinea pig brain slices from the parietal region. Extracellularly recorded compound action potentials (CAPs) were evoked by either single stimulus or high frequency stimulation (40-80 Hz). The CAP in rats consisted of an early component (fast axons, 1.2-1.8 m/s) and a late component (slow axons, 0.5-0.7 m/s), while in the guinea pig only the slow phase was observed. Diphenylhydantoin increased the latency of a single response by 10%, and had no effect on the CAP amplitude. In contrast, both phenobarbital and pentobarbital reduced the amplitude of singly evoked CAPs. Stimulation at high frequency alone decreased the CAP amplitude by 10-20%. Identical stimulation in the presence of the drugs further suppressed the CAP amplitude by an additional 31%, with varying degree of drug efficacy. The depressant effect was significant for the slow axons but the fast axons were virtually unaffected by any of the drugs. The results are consistent with the hypothesis that the antiepileptic drugs DPH, Phe and Pnt may block axonal conduction from an epileptic focus into neighbouring areas of the brain.
在大鼠和豚鼠顶叶区域脑片的胼胝体中，研究了各种抗惊厥药物对中枢轴突传导的频率依赖性效应。通过单次刺激或高频刺激（40 - 80 Hz）诱发细胞外记录的复合动作电位（CAPs）。大鼠的CAP由一个早期成分（快速轴突，1.2 - 1.8 m/s）和一个晚期成分（慢速轴突，0.5 - 0.7 m/s）组成，而在豚鼠中仅观察到慢相。苯妥英使单次反应的潜伏期增加了10%，对CAP幅度没有影响。相比之下，苯巴比妥和戊巴比妥都降低了单次诱发的CAP幅度。单独高频刺激使CAP幅度降低了10 - 20%。在药物存在的情况下进行相同刺激，进一步使CAP幅度额外降低了31%，药物疗效程度各异。这种抑制作用对慢速轴突很显著，但快速轴突实际上不受任何一种药物的影响。这些结果与抗癫痫药物苯妥英（DPH）、苯巴比妥（Phe）和戊巴比妥（Pnt）可能阻断从癫痫病灶到大脑相邻区域的轴突传导这一假设一致。
