GABA- and glutamate-mediated network activity in the hippocampus of neonatal and juvenile rats revealed by fast calcium imaging
GABA- and glutamate-mediated network activity in the hippocampus of neonatal and juvenile rats revealed by fast calcium imaging
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DOI：
10.1054/ceca.1999.0086
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发表时间：
2000-01-01
期刊：
影响因子：
4
通讯作者：
Cherubini, E
中科院分区：
文献类型：
--
作者：
Canepari, M;Mammano, F;Cherubini, E
在大鼠海马体中，出生后第一周，网络活动的特点是 GABA 驱动的巨大去极化电位 (GDP)，与钙信号相关，当 GABA(A) 拮抗剂荷包牡丹碱应用于浴液时，钙信号很容易被阻断。在出生后第一周结束时，伴随着 GABA 反应从去极化方向转向超极化方向，功能性谷氨酸能连接开始出现。在此发育阶段，荷包牡丹碱的应用可阻断 GABA(A) 介导的抑制并诱导发作间期癫痫样放电的出现。在本实验中，我们使用高时空分辨率成像系统在数十毫秒的时间尺度上比较 GABA 能或谷氨酸能网络内产生的快速钙瞬变的发生和传播。我们发现，在出生后第一周，与诱发 GDP 相关的钙信号是由跨越辐射层和锥体层的神经元局部电路的激活产生的。在存在犬尿酸（一种广谱离子型谷氨酸拮抗剂）的情况下，局部应用 GABA 会引发类似的激活模式，并被荷包牡丹碱阻断。在出生后第二周，在荷包牡丹碱存在的情况下，通过刺激谷氨酸纤维引起的与发作间期放电相关的钙信号沿着从齿状回到CA1海马区域的明确的三突触通路传播。 (C) 哈考特出版有限公司 2000。
In the rat hippocampus, during the first postnatal week, network activity is characterized by GABA-driven giant depolarizing potentials (GDPs) associated with calcium signals that are readily blocked when the GABA(A) antagonist bicuculline is applied to the bath. Towards the end of the first postnatal week, in concomitance with the shift of GABA responses from the depolarizing to the hyperpolarizing direction, functional glutamatergic connections start appearing. At this developmental stage, application of bicuculline blocks GABA(A)-mediated inhibition and induces the appearance of interictal epileptiform discharges. In the present experiments, we have used a high spatio-temporal resolution imaging system to compare, on a time scale of tens of ms, the onset and propagation of fast calcium transients generated within a GABAergic or glutamatergic network. We found that, during the first postnatal week, calcium signals associated to evoked GDPs arise from the activation of a local circuitry of neurons spanning the stratum radiatum and the pyramidal layer. Similar activation patterns were elicited by focal application of GABA in the presence of kynurenic acid, a broad spectrum ionotropic glutamatergic antagonist, and were blocked by bicuculline. During the second postnatal week, in the presence of bicuculline, calcium signals associated with interictal discharges evoked by stimulation of glutamatergic fibres propagated along the well-defined three-synaptic pathway from the dentate gyrus to the CA1 hippocampal area. (C) Harcourt Publishers Ltd 2000.