Dantas-Ferreira Rosana F, Dumont Stéphanie, Gourmelen Sylviane, Cipolla-Neto José, Simonneaux Valérie, Pévet Paul, Challet Etienne
Department of Neurobiology of Rhythms, Institute of Cellular and Integrative Neurosciences, UPR 3212 CNRS, University of Strasbourg, Strasbourg, France; Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
Department of Neurobiology of Rhythms, Institute of Cellular and Integrative Neurosciences, UPR 3212 CNRS, University of Strasbourg, Strasbourg, France.
PLoS One. 2015 May 13;10(5):e0126519. doi: 10.1371/journal.pone.0126519. eCollection 2015.
When food availability is restricted, animals adjust their behavior according to the timing of food access. Most rodents, such as rats and mice, and a wide number of other animals express before timed food access a bout of activity, defined as food-anticipatory activity (FAA). One notable exception amongst rodents is the Syrian hamster, a photoperiodic species that is not prone to express FAA. The present study was designed to understand the reasons for the low FAA in that species. First, we used both wheel-running activity and general cage activity to assess locomotor behavior. Second, the possible effects of photoperiod was tested by challenging hamsters with restricted feeding under long (LP) or short (SP) photoperiods. Third, because daytime light may inhibit voluntary activity, hamsters were also exposed to successive steps of full and skeleton photoperiods (two 1-h light pulses simulating dawn and dusk). When hamsters were exposed to skeleton photoperiods, not full photoperiod, they expressed FAA in the wheel independently of daylength, indicating that FAA in the wheel is masked by daytime light under full photoperiods. During FAA under skeleton photoperiods, c-Fos expression was increased in the arcuate nuclei independently of the photoperiod, but differentially increased in the ventromedial and dorsomedial hypothalamic nuclei according to the photoperiod. FAA in general activity was hardly modulated by daytime light, but was reduced under SP. Together, these findings show that food-restricted Syrian hamsters are not prone to display FAA under common laboratory conditions, because of the presence of light during daytime that suppresses FAA expression in the wheel.
当食物供应受到限制时，动物会根据获取食物的时间来调整其行为。大多数啮齿动物，如大鼠和小鼠，以及许多其他动物，在定时获取食物之前会表现出一阵活动，定义为食物预期活动（FAA）。啮齿动物中的一个显著例外是叙利亚仓鼠，这是一种光周期物种，不容易表现出FAA。本研究旨在了解该物种FAA较低的原因。首先，我们使用跑步轮活动和一般笼内活动来评估运动行为。其次，通过在长（LP）或短（SP）光周期下对仓鼠进行限食挑战，测试光周期的可能影响。第三，由于白天的光线可能会抑制自发活动，仓鼠还暴露于完整和骨架光周期的连续阶段（两个模拟黎明和黄昏的1小时光脉冲）。当仓鼠暴露于骨架光周期而非完整光周期时，它们在跑步轮中表现出与日长无关的FAA，这表明在完整光周期下，跑步轮中的FAA被白天的光线掩盖。在骨架光周期下的FAA期间，弓状核中的c-Fos表达与光周期无关而增加，但根据光周期，腹内侧和背内侧下丘脑核中的c-Fos表达差异增加。一般活动中的FAA几乎不受白天光线的调节，但在SP下会降低。总之，这些发现表明，由于白天存在抑制跑步轮中FAA表达的光线，食物受限的叙利亚仓鼠在常见实验室条件下不容易表现出FAA。
