Departments of Neurobiology and Neurology and Physiology, Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA.
J Neurosci. 2010 Jun 30;30(26):8993-9006. doi: 10.1523/JNEUROSCI.1183-10.2010.
Perisomatic inhibition from basket cells plays an important role in regulating pyramidal cell output. Two major subclasses of CA1 basket cells can be identified based on their expression of either cholecystokinin (CCK) or parvalbumin. This study examined their fates in the mouse pilocarpine model of temporal lobe epilepsy. Overall, immunohistochemical labeling of GABAergic boutons in the pyramidal cell layer of CA1 was preserved in the mouse model. However, CCK-labeled boutons in this layer were chronically reduced, whereas parvalbumin-containing boutons were conserved. Immunohistochemistry for cannabinoid receptor 1 (CB(1)), another marker for CCK-containing basket cells, also labeled fewer boutons in pilocarpine-treated mice. Hours after status epilepticus, electron microscopy revealed dark degenerating terminals in the pyramidal cell layer with lingering CCK and CB(1) immunoreactivity. In mice with recurrent seizures, carbachol-induced enhancement of spontaneous IPSCs (sIPSCs) originating from CCK-containing basket cells was accordingly reduced in CA1 pyramidal cells. By suppressing sIPSCs from CCK-expressing basket cells, a CB(1) agonist reverted the stimulatory effects of carbachol in naive mice to levels comparable with those observed in cells from epileptic mice. The agatoxin-sensitive component of CA1 pyramidal cell sIPSCs from parvalbumin-containing interneurons was increased in pilocarpine-treated mice, and miniature IPSCs were reduced, paralleling the decrease in CCK-labeled terminals. Altogether, the findings are consistent with selective reduction in perisomatic CA1 pyramidal cell innervation from CCK-expressing basket cells in mice with spontaneous seizures and a greater reliance on persisting parvalbumin innervation. This differential alteration in inhibition may contribute to the vulnerability of the network to seizure activity.
发自篮状细胞的树突抑制在调节锥体细胞输出中起着重要作用。根据其表达的胆囊收缩素 (CCK) 或钙结合蛋白 (parvalbumin),可以将 CA1 的两种主要篮状细胞亚类区分开来。本研究在匹罗卡品诱导的颞叶癫痫小鼠模型中研究了它们的命运。总的来说,CA1 锥体细胞层中的 GABA 能末梢的免疫组织化学标记在小鼠模型中得到保留。然而,该层中的 CCK 标记末梢长期减少,而含有 parvalbumin 的末梢则保持不变。大麻素受体 1 (CB(1)) 的免疫组织化学标记,另一种用于标记 CCK 含有篮状细胞的标志物,也显示在匹罗卡品处理的小鼠中标记的末梢较少。癫痫持续状态后数小时,电子显微镜显示在锥体细胞层中出现暗变性的终末,伴有持续的 CCK 和 CB(1)免疫反应性。在有复发性发作的小鼠中,源自 CCK 含有篮状细胞的 carbachol 诱导的自发性 IPSC (sIPSCs) 的增强相应减少。通过抑制 CCK 表达的篮状细胞的 sIPSCs,CB(1)激动剂将 carbachol 在未处理的小鼠中的刺激作用恢复到与癫痫小鼠细胞中观察到的水平相当的水平。匹罗卡品处理的小鼠中,来自含有 parvalbumin 的中间神经元的 CA1 锥体细胞 sIPSCs 的 agatoxin 敏感成分增加,而微小 IPSC 减少,与 CCK 标记末梢的减少平行。总的来说,这些发现与自发性发作小鼠中来自表达 CCK 的篮状细胞的 CA1 锥体细胞树突抑制的选择性减少以及对持续存在的 parvalbumin 抑制的依赖增加一致。这种抑制的差异改变可能导致网络对癫痫活动的易感性增加。