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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, 刘应兵, 张莉, 赵妍君, 王蕾, 胡志安

第三军医大学西南医院眼科，重庆400038

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4一28 d SD大鼠视皮层神经元的突触后电流(postsynapticcurrents, 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，不同年龄的神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

Charges in electrophysiological and morphological properties of neurons durirng the development of the visual cortex in the rat

TU Ya- Li , LIU Ying Binge, ZHANG Li, ZHAO YanJun, Wang Lei, HU Zhi- An

'Department of Ophthalmology, Southwest Hospital, Third Military Medical University, Chongqing400038. and Department of Physiology, Pharmacology, and Histology and Embryology, West China University of Medical Science，Chengdu 610041A

Abstract

To investigate the intracellular mechanism of activity-dependent synapses formation and redistribution，we studied the elect rophysiological and morphological characteristics of neurons of the developing visual cortex，and observed the level of synchronism of age and changes in the 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 d 4一28).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 that 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 Gt2)，low amplitude(一0. 87mA) and short decay time(一0. 98 ms).During postnatal week 4，all cells were mature with lower in-
put resistance(RN<310 M Q)，larger amplitude(一6 6 m A)，and longer decay time(一225 ms).From postnatal weeks 1 to 3，the cells had elect rophysiological properties that were intermediate between the immature and mature types of cells.With biocytin intracellular staining，five types of neurons were ob-
tained:nvramidal cells，satellite cells，basket cells，neuroEllial cells and immature cells.On the basis of their elect rophysiological and morphological characteristics，pyramidal cells were classified into three cate-
gories:i m mature，inte r me diate，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，the 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 elect rophysiological properties that were intermediate between the immature and mature cell types.Three distinctive types of pyramidal cells in visual cortex only co-exist during postnatal weeks 1 to 2 .Data show that activity- dependent synapes are formed and integrated into local neuronal networks with visual stimulation.In the critical period of visual development，the level of synchronism of age and changes 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

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引用本文：

涂娅莉, 刘应兵, 张莉, 赵妍君, 王蕾, 胡志安. 大鼠视皮层神经元电生理和形态学特性在发育中的变化[J]. 生理学报 2003; 55 (2): .

TU Ya- Li , LIU Ying Binge, ZHANG Li, ZHAO YanJun, Wang Lei, HU Zhi- An. Charges in electrophysiological and morphological properties of neurons durirng the development of the visual cortex in the rat. Acta Physiol Sin 2003; 55 (2): (in Chinese with English abstract).