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首页> 外文期刊>The European Journal of Neuroscience >Ca 2+-dependent ion channels underlying spontaneous activity in insect circadian pacemaker neurons
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Ca 2+-dependent ion channels underlying spontaneous activity in insect circadian pacemaker neurons

机译：Ca 2+依赖性离子通道在昆虫生物钟起搏器神经元中的自发活动中

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摘要

Electrical activity in the gamma frequency range is instrumental for temporal encoding on the millisecond scale in attentive vertebrate brains. Surprisingly, also circadian pacemaker neurons in the cockroach Rhyparobia maderae (Leucophaea maderae) employ fast spontaneous rhythmic activity in the gamma band frequency range (20-70Hz) together with slow rhythmic activity. The ionic conductances controlling this fast spontaneous activity are still unknown. Here, Ca 2+ imaging combined with pharmacology was employed to analyse ion channels underlying spontaneous activity in dispersed circadian pacemakers of the adult accessory medulla, which controls circadian locomotor activity rhythms. Fast spontaneous Ca 2+ transients in circadian pacemakers accompany tetrodotoxin (TTX)-blockable spontaneous action potentials. In contrast to vertebrate pacemakers, the spontaneous depolarisations from rest appear to be rarely initiated via TTX-sensitive sustained Na + channels. Instead, they are predominantly driven by mibefradil-sensitive, low-voltage-activated Ca 2+ channels and DK-AH269-sensitive hyperpolarisation-activated, cyclic nucleotide-gated cation channels. Rhythmic depolarisations activate voltage-gated Na + channels and nifedipine-sensitive high-voltage-activated Ca 2+ channels. Together with Ca 2+ rises, the depolarisations open repolarising small-conductance but not large-conductance Ca 2+-dependent K + channels. In contrast, we hypothesise that P/Q-type Ca 2+ channels coupled to large-conductance Ca 2+-dependent K + channels are involved in input-dependent activity.
机译：伽马频率范围内的电活动有助于注意脊椎动物大脑中毫秒级的时间编码。出人意料的是，蟑螂Rhyparobia maderae（Leucophaea maderae）中的昼夜节律起搏器神经元在γ频段频率范围（20-70Hz）内具有快速的自发性节律活动，同时具有较慢的节律活动。控制这种快速自发活性的离子电导仍然未知。在这里，Ca 2+成像与药理学相结合，用于分析成年副延髓的分散昼夜节律起搏器中自发活动背后的离子通道，从而控制昼夜运动活动节律。昼夜节律起搏器中快速自发的Ca 2+瞬变伴随着河豚毒素（TTX）可阻断的自发动作电位。与脊椎动物起搏器相比，静止状态下的自发去极化似乎很少通过TTX敏感的持续Na +通道引发。取而代之的是，它们主要受咪贝地尔敏感的，低压激活的Ca 2+通道和DK-AH269敏感的超极化激活的环状核苷酸门控阳离子通道驱动。节律性去极化激活电压门控的Na +通道和硝苯地平敏感的高压激活的Ca 2+通道。伴随Ca 2+上升，去极化打开了重新极化的小电导，但不依赖大电导的Ca 2+依赖性K +通道。相反，我们假设与大电导Ca 2+依赖性K +通道偶联的P / Q型Ca 2+通道参与了输入依赖性活动。

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