Ultrastructural features and synaptic connections of hilar ectopic granule cells in the rat dentate gyrus are different from those of granule cells in the granule cell layer
Ultrastructural features and synaptic connections of hilar ectopic granule cells in the rat dentate gyrus are different from those of granule cells in the granule cell layer
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DOI：
10.1016/s0006-8993(00)03119-x
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发表时间：
2001-02-02
期刊：
影响因子：
2.9
通讯作者：
Ribak, CE
中科院分区：
文献类型：
--
作者：
Dashtipour, K;Tran, PH;Ribak, CE
一些研究人员已经表明存在的齿状颗粒细胞在异位位置内的门和分子层使用高尔基体和逆行追踪研究，但异位颗粒细胞的超微结构特征和突触连接以前没有检查。本研究应用生物胞素逆行追踪技术，对癫痫大鼠海马脑片CA 3b透明层注射后的异位颗粒细胞进行标记。电子显微镜被用来研究位于颗粒细胞层（GCL）20-40 μ m的肺门异位颗粒细胞。它们的超微结构特征与GCL中的颗粒细胞相似，但表现出差异，包括经常显示内折叠和较厚的顶树突的核。在它们的起源，这些树突的直径为6妈妈，他们逐渐减少到2妈妈的边界与GCL。生物胞素标记的和未标记的轴突终末与肺门异位颗粒细胞的胞体和近端树突形成完全不对称的突触。这些细胞的轴体突触的平均数量是GCL中颗粒细胞的三倍。总之，这些数据表明，肝门异位颗粒细胞突触后苔藓纤维，其胞体和近端树突比颗粒细胞在GCL的抑制输入。这一发现与最近的生理学结果一致，表明癫痫大鼠的肺门异位颗粒细胞比GCL中的颗粒细胞更易过度兴奋。(C)2001爱思唯尔科技有限公司。保留所有权利。
Several investigators have shown the existence of dentate granule cells in ectopic locations within the hilus and molecular layer using both Golgi and retrograde tracing studies but the ultrastructural features and synaptic connections of ectopic granule cells were not previously examined. In the present study, the biocytin retrograde tracing technique was used to label ectopic granule cells following injections into stratum lucidum of CA3b of hippocampal slices obtained from epileptic rats. Electron microscopy was used to study hilar ectopic granule cells that were located 20-40 mum from the granule cell layer (GCL). They had ultrastructural features similar to those of granule cells in the GCL but showed differences, including nuclei that often displayed infoldings and thicker apical dendrites. At their origin, these dendrites were 6 mum in diameter and they tapered down to 2 mum at the border with the GCL. Both biocytin-labeled and unlabeled axon terminals formed exclusively asymmetric synapses with the somata and proximal dendrites of hilar ectopic granule cells. The mean number of axosomatic synapses for these cells was three times that for granule cells in the GCL. Together, these data indicate that hilar ectopic granule cells are postsynaptic to mossy fibers and have less inhibitory input on their somata and proximal dendrites than granule cells in the GCL. This finding is consistent with recent physiological results showing that hilar ectopic granule cells from epileptic rats are more hyperexcitable than granule cells in the GCL. (C) 2001 Elsevier Science B.V. All rights reserved.