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大鼠初级视皮层第II/III层侧向突触联系长时程增强的发育调控

金洲, 蔡一平, 李东升, 邓建新, 石建^*

复旦大学生命科学学院生理学和生物物理学系，上海 200433

摘要

本研究采用膜片钳全细胞记录的方法研究了Sprague-Dawley (SD)大鼠初级视皮层第II/III 层内部侧向突触联系可塑性发育变化的动态过程。采用Pairing Stimulation 的方法，分别在初级视皮层第II/III 层和第IV 层对位于第II/III 层的神经元进行长时程增强(long term potentiation, LTP)效应的诱导，并记录结果。结果显示：(1) SD 大鼠神经元第II/III 层神经元在第II/III 层到第II/III 层的水平方向和第IV 层到第II/III 层的垂直方向可分别独立诱导出突触后兴奋性电流；(2) SD 大鼠初级视皮层第II/III 层之间侧向联系的LTP 在出生后第12 天(睁眼)之前可以被水平强直刺激诱导；(3) SD 大鼠初级视皮层第II/III 层兴奋性神经元在睁眼前，水平方向的强直刺激只能诱导出从第IV 层到第II/III 层突触反应短时程增强；(4) 大鼠眼睁开(P12)后，水平方向的强直刺激可诱导出第IV 层到第II/III 层间突触联系的LTP；(5) 在大鼠出生后第14 天，当接连给予垂直方向和水平方向的强直刺激，水平方向的强直刺激使得垂直方向强直刺激诱发出的从第IV 层到第II/III 层突触联系LTP 幅度下降。这一结果提示：当两个方向的强直刺激同时给予的时候，水平输入对于垂直输入在垂直突触联系上调控有削弱的作用；(6) SD 大鼠初级视皮层第II/III 层兴奋性神经元突触AMPA 受体自发反应受发育调控。在眼睁开前，AMPA 受体自发反应的频率较低，在出生后第12~14 天内急剧上升，而在出生后第18 天后略有下降。AMPA 受体自发反应的幅度在出生后第12 天后略有下降。以上结果揭示，水平方向的突触联系强度和水平方向的输入对垂直方向的突触联系的作用都受到发育调控。第II/III 层内部水平输入对于垂直方向的输入具有双重作用，这种相互作用可能涉及神经网络形成过程中竞争机制，也可能涉及视觉功能柱的形成。

关键词： 初级视皮层; 第I I / I I I 层; 侧向联系; 长时程增强; AMPA 受体; 突触可塑性

分类号：Q424

[Developmental regulation of long term potentiation at layer II/III to II/III synapses of rat visual cortex.] [Ariticle in Chinese]

JIN Zhou, CAI Yi-Ping, LI Dong-Sheng, DENG Jian-Xin, SHI Jian^*

Department of Physiology and Biophysics, School of Life Science, Fudan University, Shanghai 200433, China

Abstract

In the present research, patch-clamp whole-cell recording was used to study the developmental changes of the internal horizontal synaptic plasticity in layer II/III of rats’ primary visual cortices. Pairing stimulation was used to induce long term potentiation (LTP) of neurons in layer II/III from layer II/III and layer IV. The data indicate that: (1) Responses of layer II/III neurons can be evoked independently at II/III-II/III and IV-II/III synapses by horizontal and vertical stimulations; (2) LTP can be induced from neurons in the layer II/III by horizontal tetanic stimulation at II/III-II/III synapses till postnatal day12 (P12, before eyes open); (3) Meanwhile, only short term potentiation (STP) at IV-II/III synapses can be induced by horizontal tetanic stimulation before eyes open; (4) After P12, a robust LTP at IV-II/III synapses can be induced by horizontal tetanic stimulation; (5) At P14, when vertical and horizontal tetanic stimulations were given to the same neuron, the LTP at IV-II/III synapses was weaker than that induced by vertical stimulation alone, suggesting that vertical synaptic modification was negatively regulated by horizontal inputs when two-direction synaptic inputs were presented at the same time; (6) Spontaneous responses of AMPA receptors (AMPARs) in the layer II/III neuron of rats’ primary visual cortices are regulated by the development. The frequency of AMPARs-mediated postsynaptic currents was at a low level before eyes open, increased sharply at P12-P14, and slightly decreased after P18. And the amplitude of spontaneous AMPARs currents slowly decreased after P12. The results demonstrated that both the strength of horizontal synaptic modification and the effects of horizontal inputs on the vertical synaptic connection are regulated by the development. II/III-II/III synaptic communication has dual effects on the IV-II/III synapses, which may be involved in a competitive machinery of neural circuitry maturation and the formation of visual function columns.

Key words: primary visual cortex; layer II/III horizontal connection; long term potentiation; AMPA receptor; synaptic plasticity;

收稿日期：2009-06-05　　录用日期：2009-08-25

通讯作者：石建　　E-mail: jianshi@fudan.edu.cn

引用本文：

金洲, 蔡一平, 李东升, 邓建新, 石建. 大鼠初级视皮层第II/III层侧向突触联系长时程增强的发育调控[J]. 生理学报 2009; 61 (5): 458-468.

JIN Zhou, CAI Yi-Ping, LI Dong-Sheng, DENG Jian-Xin, SHI Jian. [Developmental regulation of long term potentiation at layer II/III to II/III synapses of rat visual cortex.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (5): 458-468 (in Chinese with English abstract).