Spiteri N J, Prins A A, Keyser J, Strubbe J H
Physiol Behav. 1982 Dec;29(6):1141-5. doi: 10.1016/0031-9384(82)90311-0.
Previous studies suggest that feeding at dusk is probably dependent on the rat's immediate energy requirements, while feeding at dawn may have an 'anticipatory' function. However, little is known regarding the relative contribution of habit, energy deficits and circadian pacemakers in the expression of feeding behavior. The aim of the present study was to investigate the involvement of, and interplay between, habit, pacemaker synchronization and energy deficits in the occurrence of dawn feeding in rats. Light onset exerts a strong control over the timing of dawn feeding. The motivation to feed at dawn persists even when access to food is prevented during this period, and shows accompanying shifts with changes in light onset. Rats compensate their caloric deficit imposed by food restriction at dawn by eating earlier in the light phase. This feeding probably occurs in response to feedback mechanisms signalling an energy deficit. The rapid shift in dawn feeding with changes in light onset and food restriction, and its quick reappearance after discontinuing food restriction, argue against habit formation as solely responsible for the occurrence and maintenance of dawn feeding. Habit formation does play a secondary role in the maintenance, but occurs within the 'boundaries' set by the pacemaker. These experiments show that the timing and maintenance of dawn feeding are under the control of a circadian pacemaker which can be shifted by light onset only.
先前的研究表明，黄昏时进食可能取决于大鼠即时的能量需求，而黎明时进食可能具有“预期”功能。然而，关于习惯、能量亏缺和昼夜节律起搏器在进食行为表现中的相对作用，我们所知甚少。本研究的目的是调查习惯、起搏器同步和能量亏缺在大鼠黎明进食发生过程中的参与情况及其相互作用。光照开始对黎明进食的时间有很强的控制作用。即使在此期间阻止大鼠获取食物，其黎明时进食的动机依然存在，并且会随着光照开始时间的变化而发生相应改变。大鼠通过在光照阶段更早进食来弥补黎明时食物限制所造成的热量亏缺。这种进食行为可能是对表明能量亏缺的反馈机制做出的反应。黎明进食时间随光照开始时间和食物限制的变化而迅速改变，并且在停止食物限制后又迅速重新出现，这表明习惯形成并非是黎明进食发生和维持的唯一原因。习惯形成在维持过程中确实起到了次要作用，但它是在起搏器设定的“界限”内发生的。这些实验表明，黎明进食的时间和维持受昼夜节律起搏器的控制，而该起搏器只能通过光照开始时间来改变。
