Tetrodotoxin blocks the circadian effects of NMDA during the day but not at night
Tetrodotoxin blocks the circadian effects of NMDA during the day but not at night
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DOI：
10.1097/00001756-200303240-00024
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发表时间：
2003-03-24
期刊：
影响因子：
1.7
通讯作者：
Albers, HE
中科院分区：
文献类型：
--
作者：
Gamble, KL;Novak, CM;Albers, HE
光照在夜间重置视交叉上核（SCN）的生物钟，并抑制非光刺激（如注射muscimol）在白天重置生物钟的能力。由于NMDA受体的激活似乎介导了光在SCN中的作用，我们研究了SCN对NMDA的反应是否存在昼夜差异。在夜间，微注射NMDA模拟了光诱导期延迟的能力，并且这些效应不会被河豚毒素（TTX）阻断Na+依赖的动作电位所抑制。白天，NMDA模拟光抑制肌醇诱导的相推进的能力；然而，TTX抑制了这一过程。这些数据表明，NMDA需要在SCN内依赖Na+的动作电位来模拟白天的光效应，而不是在夜间。
Light resets the circadian clock in the suprachiasmatic nucleus (SCN) during the night and inhibits the ability of non-photic stimuli, such as injection of muscimol, to reset the clock during the day. Since activation of NMDA receptors appears to mediate the effects of light in the SCN, we investigated whether there are day-night differences in the SCN responses to NMDA. During the night, microinjection of NMDA mimicked the ability of light to induce phase delays, and these effects were not inhibited by blocking Na+-dependent action potentials with tetrodotoxin (TTX). During the day, NMDA mimicked the ability of light to inhibit muscimol-induced phase advances; however, this was inhibited by TTX. These data suggest that Na+-dependent action potentials within the SCN are required for NMDA to mimic the effects of light during the day but not during the night.