Postinhibitory rebound spikes are modulated by the history of membrane hyperpolarization in the SCN.
Postinhibitory rebound spikes are modulated by the history of membrane hyperpolarization in the SCN.
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DOI：
10.1111/j.1460-9568.2008.06410.x
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发表时间：
2008-09
期刊：
影响因子：
--
通讯作者：
Allen CN
中科院分区：
文献类型：
--
作者：
Tremere LA;Pinaud R;Irwin RP;Allen CN
下丘脑视交叉上核（SCN）调节生物昼夜节律时间，从而直接影响许多生理过程。SCN几乎完全由GABA能神经元组成，其中许多与SCN中的其他GABA能细胞突触，以在昼夜节律周期的大多数（如果不是所有）阶段对其突触后靶点施加抑制性影响。SCN的压倒性GABA能性质，沿着其内部连接性质，提供了一个强有力的模型来研究抑制性神经传递如何产生输出信号。在目前的工作中，我们表明，范围从5到1000毫秒的超极化引起反弹尖峰在63%的所有SCN神经元电压钳测试在成年大鼠和仓鼠的SCN。在电流钳记录，超极化导致反弹尖峰形成在所有的细胞，然而，低幅度或短持续时间的电流注入未能始终激活反弹尖峰。将超极化的持续时间从5 ms增加到1000 ms与增强的尖峰概率强烈正相关。此外，超极化的幅度对电压钳记录所揭示的尖峰幅度和电压钳或电流钳模式中获得的峰值电流的潜伏期都有很大影响。我们的研究结果表明，SCN神经元可能会使用反弹尖峰作为一种手段，产生输出信号，从一个很大程度上相互连接的GABA能神经元网络。
The suprachiasmatic nucleus of the hypothalamus (SCN) regulates biological circadian time thereby directly impacting numerous physiological processes. The SCN is composed almost exclusively of GABAergic neurons, many of which synapse with other GABAergic cells in the SCN to exert an inhibitory influence on their post-synaptic targets for most, if not all phases of the circadian cycle. The overwhelmingly GABAergic nature of the SCN, along with its internal connectivity properties, provide a strong model to examine how inhibitory neurotransmission generates output signals. In the present work we show that hyperpolarizations that range from 5 to 1000 milliseconds elicit rebound spikes in 63% of all SCN neurons tested in voltage-clamp in the SCN of adult rats and hamsters. In current-clamp recordings, hyperpolarizations led to rebound spike formation in all cells, however, low amplitude or short duration current injections failed to consistently activate rebound spikes. Increasing the duration of hyperpolarization from 5 ms to 1000 ms is strongly and positively correlated with enhanced spike probability. Additionally, the magnitude of hyperpolarization exerts a strong influence on both the amplitude of the spike, as revealed by voltage-clamp recordings, and the latency to peak current obtained in either voltage- or current-clamp mode. Our results suggest that SCN neurons may use rebound spikes as one means of producing output signals from a largely interconnected network of GABAergic neurons.
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