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小鸡脑片突触反应长时程增强的细胞内记录和多参数分析

蒋娟, 隋南, 汪萌芽

中国科学院心理研究所心理健康重点实验室，北京 100101；皖南医学院细胞电生理研究室，芜湖 241002；中国科学院研究生院，北京 100049

摘要

本文旨在建立日龄小鸡脑片制备及其神经元细胞内记录技术，观察中间腹内侧原皮质( int ermediate medialmesopallium, IMM)神经元的电学特性、突触反应及其长时程增强(long-term potentiation, LTP)现象。取2~10 日龄小鸡制备左侧前脑切片(500 μm 厚)，对69 个IMM 神经元进行细胞内记录，测得静息电位(–59.4±5.3) mV、膜斜率电阻(70.8±27.2)MΩ、时间常数(10.2±4.3) ms，动作电位幅度(85.2±9.4) mV、阈电位(–38.7±7.6) mV、超射(25.6±8.9) mV、半幅时程(2.1±0.5) ms、最大上升斜率(150.5±41.2) mV/ms、最大下降斜率(–64.3±14.0) mV/ms。其中32 个神经元的放电频率随刺激电流强度增大而升高[直线回归斜率为(21.5±10.9) Hz/nA，均P<0.05]。在所记录IMM 神经元的背侧(n=25)、腹侧(n=62)局部电刺激(0.1 Hz)均可诱发具有强度、膜电位依赖性的去极化突触反应(即EPSP)。对12 个测试细胞给予腹侧局部强直刺激(5 Hz，300 脉冲/ 串，2 串，串间隔10 min)，在6 个细胞诱导出EPSP 的LTP，呈现为EPSP 的幅度、曲线下面积、时程和最大上升斜率均增大(强直刺激后45 min 与强直刺激前相比，P<0.05，n=5)，但相应的膜电学特性无明显变化(P>0.05)。以上结果表明，在日龄小鸡脑片上建立的IMM 神经元细胞内记录技术稳定可靠，可用于突触反应LTP 的多参数分析。

关键词： 小鸡; 离体; 端脑; 突触传递; 长时程增强; 电生理学; 膜电位

分类号：R338

[Intracellular recordings and multi-parameter analysis of long-term potentiation of synaptic responses in chick brain slices.] [Ariticle in Chinese]

JIANG Juan, SUI Nan, WANG Meng-Ya

The Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China； Cell Electrophysiology Laboratory, Wannan Medical College, Wuhu 241002, China； Graduate School of Chinese Academy of Sciences, Beijing 100049, China

Abstract

Day-old chick is unique animal model in brain development and behavior study. The intermediate medial mesopallium (IMM), a region of the chick forebrain, is intimately involved in the early learning processes, which offers the ideal opportunity to study the neural changes that underlie behavioral plasticity. In this paper, the intracellular recordings were conducted from IMM neurons in chick forebrain slices, in which electrophysiological properties, synaptic responses and long-term potentiation (LTP) were observed. Coronal sections of left forebrains (500 μm thick), containing IMM, were prepared from domestic chicks, aged 2-10 days. In 69 IMM neurons, the resting membrane potential was measured to be (–59.4±5.3) mV, slope membrane resistance (70.8±27.2) MΩ, and time constant (10.2±4.3) ms. The amplitude, threshold, overshoot, half-width, max rise slope and max decay slope of action potential evoked by intracellular current injection were (85.2±9.4) mV, (–38.7±7.6) mV, (25.6±8.9) mV, (2.1±0.5) ms, (150.5±41.2) mV/ms and (–64.3±14.0) mV/ms, respectively. Spike-firing frequency was increased with depolarizing current intensity in 32 of 69 tested cells [linear regression slope was (21.5±10.9) Hz/nA, P<0.05 in all cells]. The depolarizing synaptic responses (i.e. EPSPs), with stimulus intensity- and membrane potential-dependent properties, were elicited by dorsal (n=25) or ventral (n=62) focal electrical stimuli at 0.1 Hz in all tested IMM neurons and could be nullified reversibly by perfusion with 100 μmol/L AP5 (NMDA receptor antagonist) and 3 μmol/L DNQX (non-NMDA receptor antagonist), but enlarged by 6 μmol/L bicuculline (GABAA receptor antagonist). The EPSPs evoked by ventral stimulation were persistently increased after tetanic stimulation (5 Hz, 300 pulses/train, 2 trains, train interval 10 min) in 6 of 12 tested IMM neurons. The amplitude of EPSPs was potentiated to more than 120% of control level (when analyzed at 45 min of enhancement, P<0.05, n=5), which lasted at least 30 min and then could be referred to as LTP. Moreover, area under curve, duration and max rise slope of EPSPs were also enhanced (P<0.05), while no significant changes were observed in the electrophysiological parameters of IMM neurons following induction of LTP (P>0.05). These results suggest that the intracellular recording techniques in the chick brain slices can be used to perform multi-parameter analysis of synaptic responses and their LTP.

Key words: chickens; in vitro; telencephalon; synaptic transmission; long-term potentiation; electrophysiology; membrane potentials

收稿日期：2009-08-11　　录用日期：2009-10-16

通讯作者：隋南,汪萌芽　　E-mail: suin@psych.ac.cn, wangmy@wnmc.edu.cn

引用本文：

蒋娟, 隋南, 汪萌芽. 小鸡脑片突触反应长时程增强的细胞内记录和多参数分析[J]. 生理学报 2009; 61 (6): 577-584.

JIANG Juan, SUI Nan, WANG Meng-Ya. [Intracellular recordings and multi-parameter analysis of long-term potentiation of synaptic responses in chick brain slices.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (6): 577-584 (in Chinese with English abstract).