Nagano Mamoru, Adachi Akihito, Masumoto Koh-hei, Meyer-Bernstein Elizabeth, Shigeyoshi Yasufumi
Department of Anatomy and Neurobiology, Kinki University School of Medicine 377-2 Ohno-Higashi, Osakasayama City, Osaka 589-8511, Japan.
Brain Res. 2009 Sep 15;1289:37-48. doi: 10.1016/j.brainres.2009.06.051. Epub 2009 Jun 24.
Photic resetting of a biological clock is one of the fundamental characteristics of circadian systems and allows living organisms to adjust to a particular environment. Nocturnal light induces the Per1 and Per2 genes, which leads to a resetting of the circadian clock in the suprachiasmatic nucleus (SCN), the mammalian circadian center. In our present study, we investigated whether light differentially induces the rat Per1 (rPer1) and Per2 (rPer2) genes to enable resetting of their circadian clocks. In a 24-hour LD cycle (12 h light:12 h dark), which is shorter than the normal free-running period for rats, Per1 alone showed strong induction in the ventrolateral region of the SCN (VLSCN) during the early day. In contrast, in a 25 hour LD cycle (12.5 h light:12.5 h dark), which is longer than the free running period for these animals, rPer2 alone was strongly induced in the VLSCN, at the end of the light phase and during the early dark periods. Our current findings therefore suggest that Per1 and Per2 are differentially regulated for daily entrainment to the LD cycle.
生物钟的光重置是昼夜节律系统的基本特征之一，它使生物体能够适应特定的环境。夜间光照会诱导Per1和Per2基因，从而导致视交叉上核（SCN）（哺乳动物的昼夜节律中心）的生物钟重置。在我们目前的研究中，我们调查了光照是否会差异诱导大鼠的Per1（rPer1）和Per2（rPer2）基因，从而使其生物钟得以重置。在一个24小时的明暗周期（12小时光照：12小时黑暗）中，该周期短于大鼠正常的自由运行周期，在一天的早些时候，只有Per1在视交叉上核腹外侧区域（VLSCN）表现出强烈的诱导。相反，在一个25小时的明暗周期（12.5小时光照：12.5小时黑暗）中，该周期长于这些动物的自由运行周期，在光照阶段结束时和黑暗初期，只有rPer2在VLSCN中被强烈诱导。因此，我们目前的研究结果表明，Per1和Per2在每日对明暗周期的同步化过程中受到差异调节。
