Yamauchi T, Newman S E, Ajmone-Marsan C
Arch Ital Biol. 1984 Dec;122(4):281-300.
This investigation was carried out to clarify the mechanisms for production of different seizure threshold. To study this problem changes of a single cell activity were examined by means of penicillin iontophoretical application to a single cell of both low seizure threshold hippocampus and the high seizure threshold olfactory bulb, and also topical application to the surface of hippocampus and olfactory bulb. Penicillin was applied iontophoretically using five barrel glass micropipettes. Extracellular recordings from 58 hippocampal pyramidal cells and 68 olfactory bulb mitral cells were analyzed. Penicillin increased the firing rate in most of both hippocampal pyramidal and olfactory bulb mitral cells. This suggests that penicillin finally had an excitatory effect on both cells. The results from the experiments of intermittent and continuous GABA application on a cell during penicillin iontophoresis revealed that GABA inhibitory action was reduced by penicillin in both cells. A progressively shortened duration of the post-discharge inhibition during penicillin iontophoresis also suggested that penicillin may reflect a decrease of GABA inhibitory action. No obvious seizure activity and/or no change of firing pattern were observed even after long penicillin iontophoresis. There was no significant different responses to penicillin iontophoresis in the hippocampus and the olfactory bulb single cell. Extracellular activity from 64 hippocampal pyramidal cells and 32 olfactory bulb mitral cells was recorded. The effects of penicillin topical application on single cell function were examined. From hippocampus surface, paroxysmal activity begun to appear within 6 min after topical application, and became more regular and stereotyped in form. The firing rate initially decreased in the majority of cells, with no increase prior to interictal or ictal events. The unit responses to both intermittent and continuous GABA iontophoresis was suppression in unit firing incidence, except for the burst patterns associated with the surface interictal or ictal discharges. Post-discharge inhibition was not significantly different either before or after the onset of the surface interictal discharges. These results indicate the firing rate and inhibitory function of the hippocampal pyramidal cells were not significantly changed during and following the development of interictal and/or ictal epileptiform activity. Olfactory bulb surface activity was not significantly changed and no epileptiform activity was observed even several hours after topical penicillin application.(ABSTRACT TRUNCATED AT 400 WORDS)
本研究旨在阐明产生不同癫痫发作阈值的机制。为研究此问题，通过将青霉素离子导入低癫痫发作阈值的海马体和高癫痫发作阈值的嗅球的单个细胞，并局部应用于海马体和嗅球表面，来检测单个细胞活动的变化。使用五管玻璃微吸管进行青霉素离子导入。对58个海马体锥体细胞和68个嗅球二尖瓣细胞进行了细胞外记录分析。青霉素使大多数海马体锥体细胞和嗅球二尖瓣细胞的放电频率增加。这表明青霉素最终对这两种细胞都有兴奋作用。在青霉素离子导入期间对细胞进行间歇性和持续性γ-氨基丁酸（GABA）应用的实验结果显示，青霉素使这两种细胞中的GABA抑制作用减弱。青霉素离子导入期间放电后抑制的持续时间逐渐缩短，这也表明青霉素可能反映了GABA抑制作用的降低。即使长时间进行青霉素离子导入，也未观察到明显的癫痫活动和/或放电模式的改变。海马体和嗅球单个细胞对青霉素离子导入的反应没有显著差异。记录了64个海马体锥体细胞和32个嗅球二尖瓣细胞的细胞外活动。检测了青霉素局部应用对单个细胞功能的影响。从海马体表面来看，局部应用后6分钟内开始出现阵发性活动，且形式变得更加规律和刻板。大多数细胞的放电频率最初下降，在发作间期或发作期事件之前没有增加。除了与表面发作间期或发作期放电相关的爆发模式外，对间歇性和持续性GABA离子导入的单位反应是单位放电发生率受到抑制。表面发作间期放电开始前后，放电后抑制没有显著差异。这些结果表明，在发作间期和/或发作期癫痫样活动的发展过程中及之后，海马体锥体细胞的放电频率和抑制功能没有显著变化。嗅球表面活动没有显著变化，即使局部应用青霉素数小时后也未观察到癫痫样活动。（摘要截取自400字）
