LeGates Tara A, Altimus Cara M
Department of Biology, John Hopkins University, USA.
J Vis Exp. 2011 Feb 4(48):2463. doi: 10.3791/2463.
Circadian rhythms are physiological functions that cycle over a period of approximately 24 hours (circadian- circa: approximate and diem: day). They are responsible for timing our sleep/wake cycles and hormone secretion. Since this timing is not precisely 24-hours, it is synchronized to the solar day by light input. This is accomplished via photic input from the retina to the suprachiasmatic nucleus (SCN) which serves as the master pacemaker synchronizing peripheral clocks in other regions of the brain and peripheral tissues to the environmental light dark cycle. The alignment of rhythms to this environmental light dark cycle organizes particular physiological events to the correct temporal niche, which is crucial for survival. For example, mice sleep during the day and are active at night. This ability to consolidate activity to either the light or dark portion of the day is referred to as circadian photoentrainment and requires light input to the circadian clock. Activity of mice at night is robust particularly in the presence of a running wheel. Measuring this behavior is a minimally invasive method that can be used to evaluate the functionality of the circadian system as well as light input to this system. Methods that will covered here are used to examine the circadian clock, light input to this system, as well as the direct influence of light on wheel running behavior.
昼夜节律是一种生理功能，其周期约为24小时（circadian——circa：大约，diem：天）。它们负责调节我们的睡眠/觉醒周期和激素分泌。由于这个周期并非精确的24小时，所以通过光输入与太阳日同步。这是通过视网膜向视交叉上核（SCN）的光信号输入来实现的，视交叉上核作为主起搏器，将大脑其他区域和外周组织中的外周生物钟与环境明暗周期同步。节律与这种环境明暗周期的同步将特定的生理事件安排到正确的时间生态位，这对生存至关重要。例如，小鼠白天睡觉，晚上活跃。这种将活动集中在一天中的光照或黑暗时段的能力被称为昼夜光诱导，并且需要光输入到生物钟。小鼠在夜间的活动尤其活跃，特别是在有跑轮的情况下。测量这种行为是一种微创方法，可用于评估昼夜节律系统的功能以及该系统的光输入。这里将介绍的方法用于研究生物钟、该系统的光输入以及光对跑轮行为的直接影响。
