DeCoursey P J
Biology Department, University of South Carolina, Columbia 29208.
J Biol Rhythms. 1986 Fall;1(3):171-86. doi: 10.1177/074873048600100301.
Experiments were carried out using simulated den cages to delineate specific characteristics of phase delaying in circadian photoentrainment of a nocturnal rodent, the flying squirrel. The principal experiments entailed presentation of one to five consecutive 15-min white-light pulses per activity cycle at activity onset to animals free-running in darkness, in order to determine the immediate and final phase-shifting effect. Auxiliary experiments recorded entrainment patterns on light-dark (LD) schedules in the den cages. Phase response curves (PRCs) based on 15-min white-light pulses in standard wheel cages were also constructed for these animals as background information for interpreting the phase-delaying experiments. Exposure of a den animal to light by light sampling at the time of initial arousal from the rest state at circadian time (CT) 12, either by an LD schedule or by a 15-min light pulse, resulted in a return to the nest box for a short rest period. The phase delay occurring after a single light exposure at activity onset was equal to the induced rest, thus suggesting an immediate phase shift. The maximum delay was about 1 1/2 hr/cycle, with the amount of delay related to the number of light exposures. During the photoentrained state on an LD schedule, the activity rhythm of a den-housed animal was essentially free-running on the days following a phase delay. The data are used to expand current models for photoentrainment of circadian activity rhythms in nocturnal rodents.
实验采用模拟洞穴笼进行，以描绘夜间啮齿动物飞鼠在昼夜光调节中相位延迟的特定特征。主要实验包括在黑暗中自由活动的动物每个活动周期开始时，向其呈现一到五个连续的15分钟白光脉冲，以确定即时和最终的相位移动效应。辅助实验记录了洞穴笼中明暗（LD）周期下的调节模式。还为这些动物构建了基于标准轮笼中15分钟白光脉冲的相位响应曲线（PRC），作为解释相位延迟实验的背景信息。在昼夜时间（CT）12从静止状态最初觉醒时，通过LD周期或15分钟光脉冲对洞穴中的动物进行光采样，会导致其返回巢箱进行短暂休息。在活动开始时单次光照后出现的相位延迟与诱导的休息时间相等，因此表明存在即时相位移动。最大延迟约为1.5小时/周期，延迟量与光照次数有关。在LD周期的光调节状态下，洞穴中动物的活动节律在相位延迟后的几天基本上是自由运行的。这些数据用于扩展当前关于夜间啮齿动物昼夜活动节律光调节的模型。
