Feuers R J, Delongchamp R R, Scheving L E, Casciano D A, Tsai T H, Pauly J E
Department of Health and Human Services, Food and Drug Administration, Jefferson, AR 72079.
Chronobiol Int. 1986;3(4):221-35. doi: 10.3109/07420528609079540.
The activities of 23 brain or liver enzymes were studied in 5-6 week old C57BL/6JNctr male and female mice that had been fed ad libitum and standardized for 2 weeks to either (1) 12 hr of light (0600-1800) alternating with 12 hr of darkness (1800-0600) (LD 12:12), (2) staggered sequences of 12 hr of light and 12 hr of dark (SLD 12:12) or (3) continuous illumination (LL 12:12) for 2 weeks. Mice in the LD 12:12 and LL 12:12 experiments were killed at 4 hr intervals along a 24-hr span in order to sample at six different circadian stages. Lighting schedules for mice in the SLD 12:12 experiment were organized such that six different circadian stages were sampled when all mice were killed at one time of day. All 23 enzymes demonstrated a prominent circadian rhythm in at least one of the experiments. Moreover, about two-thirds of the enzymes in LD and SLD 12:12 had a statistically significant fit to a 24-hr cosine curve, while only one-third of the enzymes in LL 12:12 had significant fits to cosine curves. Peak activities of enzymes from mice in LD 12:12 were clustered at the time of transition from light to dark. This was also the trend for the activities of enzymes from mice in SLD 12:12, but resynchronization did not appear completed within the 2-week span. This, along with the observation that mesors (mean 24-hr activity) were reduced and amplitudes altered, indicated that the 2-week standardization period was not sufficient for some enzymes. Times of peak activities, mesors and amplitudes were affected for most enzymes from mice in the LL 12:12 environment. This suggests that individual mice became desynchronized from one another with respect to the original light-dark schedule and that rhythms were altered or lost because individual mice were free running with frequencies different from 24 hr.
在5至6周龄的C57BL/6JNctr雄性和雌性小鼠中研究了23种脑或肝酶的活性。这些小鼠一直随意进食，并在两周内标准化为以下三种光照模式之一：（1）12小时光照（06:00 - 18:00）与12小时黑暗（18:00 - 06:00）交替（LD 12:12）；（2）12小时光照和12小时黑暗的交错序列（SLD 12:12）；或（3）持续光照（LL 12:12），持续两周。在LD 12:12和LL 12:12实验中，小鼠在24小时内每隔4小时处死一只，以便在六个不同的昼夜节律阶段取样。SLD 12:12实验中小鼠的光照时间表安排为，当所有小鼠在一天中的同一时间处死时，能获取六个不同的昼夜节律阶段样本。在至少一个实验中，所有23种酶都表现出显著的昼夜节律。此外，LD和SLD 12:12中约三分之二的酶与24小时余弦曲线有统计学上的显著拟合，而LL 12:12中只有三分之一的酶与余弦曲线有显著拟合。LD 12:12中小鼠酶的峰值活性聚集在从光到暗的转换时刻。SLD 12:12中小鼠酶的活性也有这个趋势，但在两周内重新同步似乎未完成。这一点，再加上中值（24小时平均活性）降低和振幅改变的观察结果，表明两周的标准化期对某些酶来说是不够的。LL 12:12环境中小鼠的大多数酶的峰值活性时间、中值和振幅都受到了影响。这表明，就原来的明暗时间表而言，个体小鼠彼此之间变得不同步，并且由于个体小鼠以不同于24小时的频率自由运行，节律发生了改变或丧失。
