Department of Neurobiology, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, GA 30310, USA.
Neuron. 2013 Nov 20;80(4):973-83. doi: 10.1016/j.neuron.2013.08.022.
Interactions among suprachiasmatic nucleus (SCN) neurons are required for robust circadian rhythms entrained to local time. To investigate these signaling mechanisms, we developed a functional coupling assay that uniquely captures the dynamic process by which SCN neurons interact. As a population, SCN neurons typically display synchronized rhythms with similar peak times, but will peak 6-12 hr apart after in vivo exposure to long days. Once they are removed from these conditions, SCN neurons resynchronize through a phase-dependent coupling process mediated by both vasoactive intestinal polypeptide (VIP) and GABAA signaling. Notably, GABAA signaling contributes to coupling when the SCN network is in an antiphase configuration, but opposes synchrony under steady-state conditions. Further, VIP acts together with GABAA signaling to couple the network in an antiphase configuration, but promotes synchrony under steady-state conditions by counteracting the actions of GABAA signaling. Thus, SCN neurons interact through nonredundant coupling mechanisms influenced by the state of the network.
视交叉上核（SCN）神经元之间的相互作用是与当地时间同步的强大节律所必需的。为了研究这些信号机制，我们开发了一种功能偶联测定法，该方法独特地捕获了 SCN 神经元相互作用的动态过程。作为一个群体，SCN 神经元通常表现出具有相似峰值时间的同步节律，但在体内暴露于长日之后，它们会相隔 6-12 小时达到峰值。一旦它们脱离这些条件，SCN 神经元就会通过由血管活性肠肽（VIP）和 GABA 信号介导的与相位相关的偶联过程重新同步。值得注意的是，当 SCN 网络处于反相配置时，GABA 信号会促进偶联，但在稳定状态下会反对同步。此外，VIP 与 GABA 信号一起作用，将网络置于反相配置中，但通过抵消 GABA 信号的作用，在稳定状态下促进同步。因此，SCN 神经元通过受网络状态影响的非冗余偶联机制相互作用。
