生理学报Acta Physiologica Sinica, April
研究论文
大鼠视皮层神经元电生理和形态学特性在发育中的变化
涂娅莉1，*, 刘应兵2, 张莉3, 赵妍君2, 王蕾4, 胡志安1
1第三军医大学西南医院眼科, 重庆 400038; 四川大学华西医学院 2生理教研室, 3药理学教研室, 4组织胚胎学教研室, 成都 610041
摘要: 为研究大鼠不同发育阶段视皮层神经元电的生理学与形态学特性, 实验观察了神经元电生理和形态学特性的变化与年龄的同步化程度, 探讨视皮层视觉依赖性突触的形成和重新分布的细胞内机制。应用脑片膜片钳全细胞记录技术和细胞内生物素标记相结合的方法, 记录4-28 d SD大鼠视皮层神经元的突触后电流(postsynaptic currents, PSCs)。共记录156个大鼠视皮层神经元, 睁眼前与睁眼后组中无反应型细胞数量， 多突触反应型细胞数量、 细胞的输入阻抗有显著性差异。成功标记23例神经元, 不同年龄神的经元的形态学成熟度不同。低输入阻抗神经元在形态学上属成熟型, 高输入阻抗神经元属幼稚型。该结果表明, 大鼠在发育过程中, 视皮层神经元功能的成熟表现为在形觉刺激以及局部神经元网络的整合作用下的视觉依赖性突触的形成和重新分布。在视觉发育可塑性关键期内, 视皮层神经元形态和电生理特性的变化与年龄的同步化程度大于皮层下结构。
关键词: 全细胞记录; 膜片钳; 脑片; 视皮层; 生物素
中图分类号: Q426
Changes in
electrophysiological and morphological
properties of neurons during
the development of the visual cortex in the rat
TU Ya-Li1，*, LIU Ying-Bing2, ZHANG Li3, ZHAO Yan-Jun2, WANG Lei4, HU Zhi-An1
1Department of Ophthalmology, Southwest Hospital, Third Military Medical University, Chongqing 400038; Departments of 2Physiology, 3Pharmacology, and 4Histology and Embryology, West China University of Medical Science, Chengdu 610041
Abstract: To investigate the intracellular mechanism of activity-dependene synapses formation and rediseribution, we studied the electrophysiological and morphological characteristics of neurons of the developing visual cortex, observed the levle of synchronism between age and changes in properties. Whole cell patch-clamp recordings and intracellular biocytin staining were used to record postsynaptic currents (PSCs) from neurons in the visual cortex of Sprague-Dawley rats (postnatal days 4-28). The histological processing was made. There were three types of PSCs in 156 cells: silent response, monosynaptic response and polysynaptic response, during the first developmental month. Before eyes opened the number of the neurons with the silent response (57.3%) was significantly higher than those after the eyes opened (11.9%) (P<0.001). However, the incidence of polysynaptic PSCs increased from 12.4% before eyes opened to 28.9% after eyes opened (P<0.01). During postnatal week 1, all cells were classified as immature. The immature cells had very high input resistances (RN>1.0 GΩ), low amplitude (-0.87 mA) and short decay time (-0.98 ms). During postnatal week 4, all cells were mature with a lower input resistance (RN<310 MΩ), larger amplitude (-66 mA), and longer decay time (-225 ms). From postnatal weeks 1 to 3, the cells had electrophysiological properties that were intermediate between the immature and mature cell types. With biocytin intracellular staining, five types of neurons were obtained: pyramidal cells, satellite cells, basket cells, neuroglial cells and immature cells. On the basis of their electrophysiological and morphological characteristics, pyramidal cells were classified into three categories: immature, intermediate, and mature cell types. During postnatal week 1, cells were immature with very high input resistance. Morphologically immature cells had short simple dendritic arborizations which incompletely penetrated the layer where the cell body lies. From postnatal weeks 2 to 4, cells were mature with low input resistance. They were morphologically more complex with dendritic arborizations which completely penetrated the whole layers of the visual cortex. From postnatal weeks 1 to 2, a third, intermediate cell type had electrophysiological properties that were intermediate between the immature and mature cell types. Three distinctive cell types co-exist among pyramidal cell of visual cortex only during postnatal weeks 1 to 2. Data show that activity-dependent synapes are form and integrated into local neuronal networks with visual stimulation. In the critical period of visual development, the level of synchronism between age and changed in electrophysiological and morphological properties in the visual cortex is higher than that in the subcortex.
Key words: whole cell recording; patch clamp; brain slice; visual cortex; biocytin