Katona C, Smale L
Department of Psychology, Michigan State University, East Lansing 48824-1117, USA.
Physiol Behav. 1997 Mar;61(3):365-72. doi: 10.1016/s0031-9384(96)00407-6.
Wheel-running behaviour of the Nile grass rat, Arvicanthis niloticus, was studied under a variety of lighting conditions to characterize circadian rhythms in this species. A series of lighting schedules was used to determine the nature of entrainment, the rates of reentrainment after 6-h phase shifts, and the stability of free-running rhythms in constant light (LL) and constant dark (DD). All 15 individuals showed peaks of activity around dawn and dusk, 11 were more likely to run when lights were on and 4 were more likely to run when the lights were off. Three of the latter animals were completely crepuscular, but 1 showed a distinctly different and relatively nocturnal pattern, remaining active well into the dark phase. All 7 animals that were exposed to 6-h phase advances and delays reentrained to both shifts within 9 days. Stable and precise free-running rhythms were exhibited by all animals in LL and DD, and periods were longer in LL than DD. The ratio of the active to the inactive phase was significantly higher in LL than in DD or LD conditions. We conclude that A. niloticus exhibit predominantly diurnal running rhythms, with peaks of activity occurring around dawn and dusk, and that their rhythms are stable and precise and respond rapidly and predictably to changes in lighting conditions.
在各种光照条件下研究了尼罗河草鼠（Arvicanthis niloticus）的转轮行为，以表征该物种的昼夜节律。采用一系列光照时间表来确定其 entrainment 的性质、6 小时相位偏移后的重新 entrainment 速率以及在持续光照（LL）和持续黑暗（DD）中自由运行节律的稳定性。所有 15 只个体在黎明和黄昏前后均表现出活动高峰，11 只在开灯时更有可能奔跑，4 只在关灯时更有可能奔跑。后一组动物中的 3 只完全是晨昏性的，但有 1 只表现出明显不同且相对夜行性的模式，在黑暗阶段仍保持活跃。所有 7 只经历了 6 小时相位提前和延迟的动物在 9 天内均重新 entrain 到两种偏移状态。所有动物在 LL 和 DD 中均表现出稳定而精确的自由运行节律，且在 LL 中的周期比 DD 中的长。LL 中活动期与非活动期的比例显著高于 DD 或 LD 条件下的比例。我们得出结论，尼罗河草鼠表现出主要为昼行性的奔跑节律，活动高峰出现在黎明和黄昏前后，并且它们的节律稳定而精确，对光照条件的变化反应迅速且可预测。
