Ibata Y, Okamura H, Tanaka M, Tamada Y, Hayashi S, Iijima N, Matsuda T, Munekawa K, Takamatsu T, Hisa Y, Shigeyoshi Y, Amaya F
Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi, Hirokoji, Kamikyoku, Kyoto, 602-8566, Japan.
Front Neuroendocrinol. 1999 Jul;20(3):241-68. doi: 10.1006/frne.1999.0180.
In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed.
在哺乳动物中，生物钟（昼夜节律振荡器）位于视交叉上核（SCN），这是一个位于视交叉上方的双侧对称的小结构。当SCN被破坏时，睡眠-觉醒和激素释放的昼夜节律消失，将胎儿或新生儿的SCN移植到无节律的宿主体内可恢复节律性。SCN中有几种肽合成神经元，其中血管活性肠肽、精氨酸加压素和生长抑素神经元最为突出。这些肽及其mRNA表现出昼夜节律性，可能受或不受光刺激的影响。视网膜神经节细胞的主要神经元输入以及来自外侧膝状体核和中缝核等其他输入对于昼夜节律的同步化和相位移动非常重要。在这篇综述中，我们描述了神经元与神经胶质成分之间的形态学和功能相互作用及其发育。我们还考虑了在主观夜间光刺激后SCN中即刻早期基因的表达及其在信号转导机制中的作用。还考虑了SCN与褪黑素之间的相互作用，褪黑素是在SCN多突触输入的影响下在松果体中合成的。最后，综述了时钟基因，特别是被认为促进昼夜节律的mPers的形态学和功能特征。
