Naito Emiko, Watanabe Tsuyoshi, Tei Hajime, Yoshimura Takashi, Ebihara Shizufumi
Division of Biomodeling, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
J Biol Rhythms. 2008 Apr;23(2):140-9. doi: 10.1177/0748730408314572.
In mammals, the suprachiasmatic nucleus (SCN), the circadian pacemaker, receives light information via the retina and functions in the entrainment of circadian rhythms and in phasing the seasonal responses of behavioral and physiological functions. To better understand photoperiod-related alterations in the SCN physiology, we analyzed the clock gene expression in the mouse SCN by performing in situ hybridization and real-time monitoring of the mPer1::luc bioluminescence. Under long photoperiod (LP) conditions, the expression rhythms of mPer1 and Bmal1 in the caudal SCN phase-led those in the rostral SCN; further, within the middle SCN, the rhythms in the ventrolateral (VL)-like subdivision advanced compared with those in the dorsomedial (DM)-like subdivision. The mPer1::luc rhythms in the entire coronal slice obtained from the middle SCN exhibited 2 peaks with a wide peak width under LP conditions. Imaging analysis of the mPer1::luc rhythms in several subdivisions of the rostral, middle, caudal, and horizontal SCN revealed wide regional variations in the peak time in the rostral half of the SCN under LP conditions. These variations were not due to alterations in the waveform of a single SCN neuronal rhythm. Our results indicate that LP conditions induce phase changes in the rhythms in multiple regions in the rostral half of the SCN; this leads to different circadian waveforms in the entire SCN, coding for day length.
在哺乳动物中，昼夜节律起搏器视交叉上核（SCN）通过视网膜接收光信息，并在昼夜节律的同步以及行为和生理功能的季节性反应的定相过程中发挥作用。为了更好地理解SCN生理学中与光周期相关的变化，我们通过进行原位杂交和对mPer1::luc生物发光进行实时监测，分析了小鼠SCN中的时钟基因表达。在长光周期（LP）条件下，尾侧SCN中mPer1和Bmal1的表达节律相位领先于头侧SCN中的表达节律；此外，在中SCN内，腹外侧（VL）样亚区的节律比背内侧（DM）样亚区的节律提前。在LP条件下，从中SCN获得的整个冠状切片中的mPer1::luc节律呈现出2个峰值，且峰值宽度较宽。对头侧、中、尾和水平SCN的几个亚区中mPer1::luc节律的成像分析显示，在LP条件下，SCN头侧半部分的峰值时间存在广泛的区域差异。这些差异并非由于单个SCN神经元节律波形的改变所致。我们的结果表明，LP条件会诱导SCN头侧半部分多个区域的节律发生相位变化；这导致整个SCN中出现不同的昼夜节律波形，编码白昼长度。
