García-Allegue R, Lax P, Madariaga A M, Madrid J A
Department of Physiology and Pharmacology (Animal Physiology Unit), University of Murcia, 30100 Murcia, Spain.
Am J Physiol. 1999 Aug;277(2):R523-31. doi: 10.1152/ajpregu.1999.277.2.R523.
The wheel running (WR) and feeding activity (FA) of Octodon degus, a new laboratory rodent characterized by its diurnal habits, were recorded under different lighting conditions. Under 12:12-h light-dark (LD 12:12) cycles, WR activity exhibited a crepuscular pattern with two peaks, M and E, associated with "dawn" and "dusk," respectively. In both cases, an anticipatory activity was patent, suggesting that, beside the masking effect of LD transitions, both peaks have an endogenous origin. This pattern, which was also observed under a skeleton photoperiod (LD 0.5:11.5), became unimodal after LD 0.5:23.5 and constant darkness (DD) exposure. Simultaneously, FA showed an arrhythmic pattern in most animals, especially under DD, when none of the animals exhibited a significant circadian rhythm. The existence of two groups of oscillators, or two oscillators, would explain most properties of the WR rhythms noted in this species. Our results show that the degu's temporal feeding strategy seems mainly arrhythmic, whereas its WR pattern is driven by a strongly circadian bimodal rhythm.
八齿鼠是一种具有昼行性习性的新型实验啮齿动物，在不同光照条件下记录了其转轮活动（WR）和进食活动（FA）。在12:12小时明暗（LD 12:12）循环下，WR活动呈现出黄昏模式，有两个峰值，分别为M和E，分别与“黎明”和“黄昏”相关。在这两种情况下，预期活动都很明显，这表明，除了LD转换的掩盖效应外，这两个峰值都有内源性起源。这种模式在骨架光周期（LD 0.5:11.5）下也有观察到，在暴露于LD 0.5:23.5和持续黑暗（DD）后变为单峰模式。同时，FA在大多数动物中呈现出无节律模式，尤其是在DD条件下，此时没有动物表现出明显的昼夜节律。两组振荡器或两个振荡器的存在可以解释该物种中WR节律的大多数特性。我们的结果表明，八齿鼠的定时进食策略似乎主要是无节律的，而其WR模式则由强烈的昼夜双峰节律驱动。
