The effects of feeding after fasting on the circadian clock in CS mice

与其他品系的小鼠和大鼠不同，CS小鼠(近交系)视交叉上核(SCN)的昼夜节律受到限制进食时间表(Rf)的影响。为了阐明CS小鼠体内RF携带的机制，本研究检测了禁食后喂养是否会重置CS小鼠昼夜节律的相位。在福井大学医学部心理学教研室建立了小鼠昼夜节律研究实验室。测定了CS和C57BL/6J小鼠在自由采食和光暗条件下的日摄食量。CS小鼠和C57BL/6J小鼠的平均日摄食量无差异。每只小鼠被安置在一个跑轮笼子里，测量在LD和恒定黑暗(DD)下的活动节律。在DD的第2天，在6个阶段(ZT2，6，10，14，18和22；ZT=Zeitgeber Time，ZT12=LD的黑暗开始)中的一个阶段禁食，并在24小时后返回笼子。禁食24小时后，6个时相的一次性喂养对CS和C57BL/6J小鼠的行为节律均无影响。在CS小鼠中，在48小时的食物剥夺后2小时，时钟基因mRNAs在SCN和其他脑区的表达。禁食后单次投喂对SCN的mPerl和mPer2mRNAs无明显影响，而对其他脑区mPer1和mPer2mRNAs的表达显著增加。这些结果表明，CS小鼠的RF携带不受单次摄食刺激对SCN生物钟的相位重置效应的调节，其他脑区的时钟基因可能在禁食后摄食时行为节律的调节中起作用。

Circadian clock in the SCN (suprachiasmatic nucleus) of CS mice (an inbred strain) is entrained by RF (restricted feeding schedule) unlike other strains of mice and rats. To clarify the mechanism of RF-entrainment in the CS mice, present study examined whether feeding after fasting resets the phase of circadian rhythm of CS mice.1. Laboratory for mouse circadian rhythm research was established in Division of Psychology, Faculty of Medical Sciences, University of Fukui.2. Daily food intakes of CS and C57BL/6J mice were measured under ad lib feeding and light-dark condition (LD). There was no difference in the mean daily food intakes between CS and C57BL/6J mice.3. Each mouse was housed in a running wheel cage and measured the activity rhythm under LD followed by constant darkness (DD). In the 2nd day of DD, food were deprived at one of 6 phases (ZT2, 6,10,14,18 and 22 ; ZT=Zeitgeber time, ZT12=dark onset of LD) and returned to the cage after 24 hours. The single feeding after 24-hour food deprivation at all 6 phases induced no changes in the behavioral rhythms in both CS and C57BL/6J mice.4. In the CS mice, clock gene mRNAs in the SCN and other brain areas at 2 hours after feeding following the 48-hour food deprivation. The single feeding after food deprivation induced no changes in the mPerl and mPer2 mRNAs in the SCN, while it significantly increased mPerl and mPer2 mRNAs in other brain areas.5. These results suggest that the RF-entrainment of CS mice is not regulated by the phase-resetting effect of single feeding stimulus on the circadian clock in the SCN, and that the clock genes in other brain areas might play a role in the regulation of behavioral rhythm under feeding after fasting.