Effects of transcranial magnetic stimulation on a reflex myoclonus model in rats

对象：由于重复电刺激（repetitive electrical，rES）和经颅磁刺激（transcranial magnetic stimulation，rTMS）对皮层神经元兴奋性的瞬时调节机制尚不清楚，本实验研究了rES和rTMS对大鼠体感诱发电位（somatosensory evoked potentials，SEP）的影响。此外，我们研究了rES对皮质反射肌阵挛在儿茶酚诱导的myolonusrates.Subjects和方法的影响：麻醉大鼠后，一对钻孔钻在右侧躯体感觉区的后肢的头骨。使用插入钻孔的两个不锈钢螺钉，以1或0.2 Hz的频率进行rES，持续3小时20分钟。右侧躯体感觉区域使用小型八位数线圈以1 Hz的频率磁刺激2小时20分钟。在rES或rTMS前后记录刺激左后肢诱发的SEP。比较rES或rTMS组与对照组SEP各成分的波幅和波幅。25 Hz-rES作用于大鼠躯体感觉区30分钟后，腹腔注射邻苯二酚（80 mg/kg）。测定儿茶酚诱发肌阵挛的发作时间和持续时间。结果：rES或rTMS刺激后SEP皮层成分波幅较对照组明显降低，皮层成分波幅较对照组明显降低。免疫组化结果显示，rES刺激后，皮质神经元内c-Fos表达增强，rES和rTMS刺激后，皮质神经元无其他组织学改变。结论：rES和rTMS对皮层神经元兴奋性的影响相似。用抗c-Fos抗体进行免疫组织化学分析，同时显示组织学变化。然而，rES对儿茶酚诱导的肌阵挛的影响仍有待解决。

Objects : Since the mechanism that repetitive electric (rES) and transcranial magnetic stimulation (rTMS) transiently modulate cortical neuron excitabilities is not clear, we studied the effects of rES and rTMS on somatosensory evoked potentials (SEPs) in rats. In addition, we studied the effects of rES on cortical reflex myoclonus in catechol-induced myolonus rats.Subjects and Methods : After anesthetizing rats, a pair of burr holes was drilled in the skull over the right somatosensory area for the hindlimb. rES was performed with a frequency of 1 or 0.2 Hz for 3 hours and 20 minutes using two stainless screws inserted into the burr holes. The right somatosensory areas were magnetically stimulated with a frequency of 1 Hz for 2 hours and 20 minutes using a small eight-figure coil. SEPs elicited by stimulating the left hindlimb was recorded before and after rES or rTMS. Amplitudes and latencies of SEP components were measured and compared between the rES or rTMS and control groups. After 25Hz-rES for 30 minutes to the somatosensory area, catechol was intraperitoneally injected (80mg/kg) to rats. Onset times and durations of catechol-induced myoclonus were measured. Changes of SEP components were also observed before and after injection of catechol.Results : Amplitudes of cortical components of SEPs were significantly reduced after rES or rTMS compared with those in the control. Immunohistological analysis showed that c-Fos expression was observed in cortical neurons stimulated by rES. There is no other histological change by rES or rTMS. rES did not significantly affect catechol-induced myoclonus and SEPs.Conclusion : The present results support that rES and rTMS have similar effects on cortical neurons excitabilities. Histological changes were simultaneously shown by immunohistological analysis using anti-c-Fos antibody. However, effects of rES on catechol-induced myoclonus remained to be solved.