Shieh Kun-Ruey, Yang Shu-Chuan, Lu Xin-Yun, Akil Huda, Watson Stanley J
Institute of Neuroscience, Tzu Chi University, Hualien 970, ROC.
J Biomed Sci. 2005;12(1):209-17. doi: 10.1007/s11373-004-8176-6.
High densities of the mRNA of three rhythm-related genes, rPeriod1 (rPer1), rPer2, and rClock, which share high homology in Drosophila and mammals, are found in the rat hypothalamic suprachiasmatic nucleus (SCN). The SCN, however, is not the only brain region that expresses these genes. To understand the possible physiological roles of these rhythm-related genes, we examined expression of these genes in different brain regions at various time points in male Sprague--Dawley rats. Using semi quantitativein situ hybridization with 35S-riboprobes to evaluate mRNA levels, the diurnal rhythmicity of rPer1, and rPer2 mRNA levels was found in the SCN, arcuate nucleus, and median eminence/pars tuberalis. Expression patterns of mRNA for rPer1 and rPer2, however, were not similar in these brain regions. The rhythmicity in these brain regions was specific, because it was not observed in the cerebellum or hippocampus. Moreover, diurnal changes in rClock mRNA expression were not detected in any of the brain regions examined. These findings suggest that the different expression patterns observed for rPer1, rPer2, and rClock mRNAs may be attributed to their different physiological roles in these brain regions, and support previous work indicating that circadian rhythms in the brain are widespread.
在大鼠下丘脑视交叉上核（SCN）中发现了三种与节律相关基因rPeriod1（rPer1）、rPer2和rClock的mRNA高密度表达，这些基因在果蝇和哺乳动物中具有高度同源性。然而，SCN并不是唯一表达这些基因的脑区。为了了解这些与节律相关基因可能的生理作用，我们在雄性斯普拉格-道利大鼠的不同时间点检测了这些基因在不同脑区的表达。使用与35S核糖探针的半定量原位杂交来评估mRNA水平，发现在SCN、弓状核和正中隆起/结节部存在rPer1和rPer2 mRNA水平的昼夜节律性。然而，rPer1和rPer2 mRNA在这些脑区的表达模式并不相似。这些脑区的节律性是特异性的，因为在小脑或海马中未观察到。此外，在所检测的任何脑区均未检测到rClock mRNA表达的昼夜变化。这些发现表明，观察到的rPer1、rPer2和rClock mRNA不同表达模式可能归因于它们在这些脑区的不同生理作用，并支持先前表明脑中昼夜节律广泛存在的研究工作。
