College of Biological and Environmental Engineering, Zhejiang Univ. of Technology, Zhaohui, Hangzhou, Zhejiang, 310032, China.
Am J Physiol Regul Integr Comp Physiol. 2010 Mar;298(3):R635-41. doi: 10.1152/ajpregu.00578.2009. Epub 2010 Jan 6.
Although studies involving the circadian response to external time cues indicate that the peripheral clocks are dominated mainly by food cues, whether and how changes in the light and food cues affect the circadian rhythm of the renal clock is still largely unknown. In the present study, we found that the circadian phases of Bmal1, Clock, Cry1, Per1, and Per2 were altered differently by the stimuli of food and light cues in the kidney. After the individual reversal of the light-dark (LD) cycle for 7 days, Per1 displayed a 4-h phase delay, whereas the peak phases of Bmal1, Clock, Cry1 and Per2 almost remained the same as those in the control condition. With regard to the feeding-induced circadian resetting of the renal clock, we found that the resetting processes of clock genes could not be completed within 7 days, suggesting a weak synchronization effect of the food cue on the renal circadian clock. Moreover, the reentrainment of the clock genes was greatly enhanced after the reversal of both the feeding schedule and the LD cycle. Noticeably, the phases of Per1 and Clock were shifted most rapidly by 12 h within 3 days after the simultaneous reversal of the feeding schedule and the LD cycle, whereas their peak phases were only shifted by 4 h and 8 h, respectively, on the 7th day after the individual reversal of the feeding schedule. Thus Per1 and Clock may play important roles in the light-induced resetting of the circadian rhythms in the kidney.
尽管涉及外部时间线索对昼夜节律反应的研究表明，外周时钟主要受食物线索的支配，但光照和食物线索的变化是否以及如何影响肾脏时钟的昼夜节律仍知之甚少。在本研究中，我们发现食物和光照线索刺激可改变肾脏中 Bmal1、Clock、Cry1、Per1 和 Per2 的昼夜相位。在单独颠倒光-暗（LD）周期 7 天后，Per1 显示出 4 小时的相位延迟，而 Bmal1、Clock、Cry1 和 Per2 的峰值相位几乎与对照条件相同。关于进食诱导的肾脏时钟昼夜节律重置，我们发现时钟基因的重置过程不能在 7 天内完成，这表明食物线索对肾脏昼夜节律时钟的同步作用较弱。此外，在颠倒喂食时间表和 LD 周期后，时钟基因的重新同步得到了极大增强。值得注意的是，在同时颠倒喂食时间表和 LD 周期后的 3 天内，Per1 和 Clock 的相位最快在 12 小时内发生变化，而在单独颠倒喂食时间表后的第 7 天，它们的峰值相位仅分别发生了 4 小时和 8 小时的变化。因此，Per1 和 Clock 可能在光诱导的肾脏节律重设中发挥重要作用。
