Edgar D M, Martin C E, Dement W C
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, California 94305.
J Biol Rhythms. 1991 Fall;6(3):185-99. doi: 10.1177/074873049100600301.
In the mouse, activity is precisely timed by the circadian clock and is normally most intense in the early subjective night. Since vigorous activity (e.g., wheel running) is thought to induce phase shifts in rodents, the temporal placement of daily exercise/activity could be a determinant of observed circadian rhythm period. The relationship between spontaneous running-wheel activity and the circadian period of free-running rhythms was studied to assess this possibility. With ad libitum access to a running wheel, mice exhibited a free-running period (tau) of 23.43 +/- 0.08 hr (mean +/- SEM). When running wheels were locked, tau increased (23.88 +/- 0.04 hr, p less than 0.03), and restoration of ad libitum wheel running again produced a shorter period (tau = 23.56 +/- 0.06 hr, p less than 0.05). A survey of free-running activity patterns in a population of 100 mice revealed a significant correlation between the observed circadian period and the time of day in which spontaneous wheel running occurred (r = 0.7314, p less than 0.0001). Significantly shorter periods were observed when running was concentrated at the beginning of the subjective night (tau = 23.23 +/- 0.04), and longer periods were observed if mice ran late in the subjective night (tau = 23.89 +/- 0.04), F (1, 99) = 34.96, p less than 0.0001. It was previously believed that the period of the circadian clock was primarily responsive to externally imposed tonic or phasic events. Systematic influences of spontaneous exercise on tau demonstrate that physiological and/or behavioral determinants of circadian timekeeping exist as well.
在小鼠中，活动由昼夜节律时钟精确计时，通常在主观夜早期最为活跃。由于剧烈活动（如轮子跑步）被认为会在啮齿动物中诱导相位变化，日常运动/活动的时间安排可能是观察到的昼夜节律周期的一个决定因素。为了评估这种可能性，研究了自发的轮子跑步活动与自由运行节律的昼夜周期之间的关系。小鼠可以随意使用轮子时，其自由运行周期（τ）为23.43±0.08小时（平均值±标准误）。当轮子被锁定时，τ增加（23.88±0.04小时，p<0.03），恢复随意使用轮子跑步后周期又变短（τ=23.56±0.06小时，p<0.05）。对100只小鼠群体的自由运行活动模式进行调查发现，观察到的昼夜周期与自发轮子跑步发生的时间之间存在显著相关性（r = 0.7314，p<0.0001）。当跑步集中在主观夜开始时，观察到明显更短的周期（τ=23.23±0.04），而如果小鼠在主观夜后期跑步，则观察到更长的周期（τ=23.89±0.04），F(1, 99)=34.96，p<0.0001。以前人们认为昼夜节律时钟的周期主要对外部施加的稳态或相位事件做出反应。自发运动对τ的系统性影响表明，昼夜计时的生理和/或行为决定因素也存在。
