Long Michael A, Jutras Michael J, Connors Barry W, Burwell Rebecca D
Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
Nat Neurosci. 2005 Jan;8(1):61-6. doi: 10.1038/nn1361. Epub 2004 Dec 5.
In the suprachiasmatic nucleus (SCN), the master circadian pacemaker, neurons show circadian variations in firing frequency. There is also considerable synchrony of spiking across SCN neurons on a scale of milliseconds, but the mechanisms are poorly understood. Using paired whole-cell recordings, we have found that many neurons in the rat SCN communicate via electrical synapses. Spontaneous spiking was often synchronized in pairs of electrically coupled neurons, and the degree of this synchrony could be predicted from the magnitude of coupling. In wild-type mice, as in rats, the SCN contained electrical synapses, but electrical synapses were absent in connexin36-knockout mice. The knockout mice also showed dampened circadian activity rhythms and a delayed onset of activity during transition to constant darkness. We suggest that electrical synapses in the SCN help to synchronize its spiking activity, and that such synchrony is necessary for normal circadian behavior.
在视交叉上核（SCN）这个主昼夜节律起搏器中，神经元的放电频率呈现昼夜变化。在毫秒级尺度上，SCN神经元之间的放电也存在相当程度的同步性，但其机制尚不清楚。通过配对全细胞记录，我们发现大鼠SCN中的许多神经元通过电突触进行通信。在电耦合的神经元对中，自发放电常常是同步的，并且这种同步程度可以根据耦合强度来预测。与大鼠一样，野生型小鼠的SCN中存在电突触，但在连接蛋白36基因敲除小鼠中则不存在电突触。基因敲除小鼠还表现出昼夜活动节律减弱以及在转入持续黑暗期间活动开始延迟。我们认为，SCN中的电突触有助于同步其放电活动，并且这种同步对于正常的昼夜行为是必要的。
