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

CS小鼠（近交系）的SCN（视交叉上核）生物钟与其他品系的小鼠和大鼠不同，受到RF（限制摄食时间表）的影响。为了阐明CS小鼠rf携带的机制，本研究考察了禁食后进食是否重置了CS小鼠的昼夜节律阶段。1 .在福井大学医学部心理学部建立了小鼠昼夜节律研究实验室。测定CS和C57BL/6J小鼠在随机饲养和光暗条件下的日摄食量。CS和C57BL/6J小鼠的平均日摄食量无显著差异。将每只小鼠置于跑轮笼中，在LD和持续黑暗（DD）下测量活动节律。在DD第2天，分别在ZT2、6、10、14、18和22期（ZT =Zeitgeber时间，ZT12= LD暗起）中的一个阶段剥夺食物，24小时后返回笼中。在所有6个阶段24小时禁食后的单次喂养均未引起CS和C57BL/6J小鼠行为节律的变化。在CS小鼠中，在48小时食物剥夺后进食2小时，对SCN和其他大脑区域的基因mrna进行计时。剥夺食物后的单次喂食未引起SCN内mPerl和mPer2 mrna的变化，但显著增加了其他脑区mPerl和mPer2 mrna的表达。这些结果表明，CS小鼠的rf携带不受单次摄食刺激对SCN生物钟的相位重置作用的调节，其他脑区生物钟基因可能在禁食后摄食下的行为节律调节中发挥作用。

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.