Welsh D K, Reppert S M
Laboratory of Developmental Chronobiology, Massachusetts General Hospital, Boston 02114, USA.
Brain Res. 1996 Jan 8;706(1):30-6. doi: 10.1016/0006-8993(95)01172-2.
Individual neurons dissociated from rat suprachiasmatic nucleus can express independently phased circadian firing rhythms in culture. The phases of these rhythms are unperturbed by reversible blockade of neuronal firing lasting 2.5 days, indicating that multiple circadian clocks continue to operate in the absence of conventional synaptic transmission. The possibility remains, however, that these circadian rhythms might depend on some other form of intercellular communication. In the present study, a potential role for gap junctional coupling in SCN cultures was evaluated by introduction of the tracer molecule Neurobiotin into both neurons (n = 98) and astrocytes (n = 10), as well as by immunolabeling for specific connexins, the molecular components of gap junctions. Astrocytes were extensively coupled to each other by connexin 43-positive gap junctions, but no evidence was found for coupling of neurons to each other or to astrocytes. These data support the hypothesis that neurons expressing independently phased circadian rhythms in SCN cultures ('clock cells') are autonomous, single cell circadian oscillators, but do not exclude a role for glia in synchronizing neuronal clock cells in vivo.
从大鼠视交叉上核分离出的单个神经元在培养物中可独立表达相位不同的昼夜节律性放电节律。这些节律的相位不受持续2.5天的神经元放电可逆性阻断的干扰，这表明在没有传统突触传递的情况下，多个生物钟仍在继续运行。然而，这些昼夜节律仍有可能依赖于某种其他形式的细胞间通讯。在本研究中，通过将示踪分子神经生物素引入神经元（n = 98）和星形胶质细胞（n = 10），以及通过对缝隙连接的分子成分——特定连接蛋白进行免疫标记，评估了缝隙连接耦合在视交叉上核培养物中的潜在作用。星形胶质细胞通过连接蛋白43阳性的缝隙连接彼此广泛耦合，但未发现神经元之间或神经元与星形胶质细胞之间存在耦合的证据。这些数据支持这样的假设，即在视交叉上核培养物中表达相位不同的昼夜节律的神经元（“时钟细胞”）是自主的单细胞昼夜振荡器，但不排除胶质细胞在体内使神经元时钟细胞同步方面的作用。
