Borer K T, Clover K
Division of Kinesiology, University of Michigan, Ann Arbor 48109.
Physiol Behav. 1994 Aug;56(2):385-91. doi: 10.1016/0031-9384(94)90211-9.
To establish the relative importance of light and food in the control of core temperature (Tc) rhythm in food-restricted hamsters, mature female hamsters maintained in 14L:10D lighting were fed restricted amounts of food at the onset of light (n = 6) or at the onset of dark (n = 6) and were compared to ad lib-fed animals. After 21-25 days of this entrainment, light stimulus was shifted by 12 h, and animals were kept in shifted lighting for another 13 days. Food restriction led to a 0.6 degree decrease in the mean Tc, which was expressed entirely during the day in night-fed hamsters and was evenly divided between day and night in day-fed animals. Thus, Tc and general activity rhythms maintained the entrainment to light under both dietary conditions, with peak values for all occurring during the early night. During 13 days following the 12-h shift in lighting, Tc and activity rhythms shifted in all animals, regardless of nutritional status, from entrainment to preceding lighting, through double rhythm frequency, indicating entrainment to preceding as well as current lighting, to entrainment to current lighting. Thus, in food-restricted hamsters, light stimulus rather than predictable timing of food prevails as the entrainer of Tc and activity rhythms.
为确定光照和食物在限制进食的仓鼠核心体温（Tc）节律控制中的相对重要性，将处于14小时光照：10小时黑暗光照条件下的成年雌性仓鼠，在光照开始时（n = 6）或黑暗开始时（n = 6）给予限制量的食物，并与自由进食的动物进行比较。在这种同步化处理21至25天后，将光照刺激提前12小时，并让动物在改变后的光照条件下再饲养13天。食物限制导致平均Tc降低0.6摄氏度，在夜间进食的仓鼠中，这种降低完全发生在白天，而在白天进食的动物中，这种降低在白天和夜间平均分布。因此，在两种饮食条件下，Tc和总体活动节律均保持对光照的同步化，所有峰值均出现在深夜。在光照提前12小时后的13天里，无论营养状况如何，所有动物的Tc和活动节律都发生了变化，从与先前光照的同步化，经过双节律频率，表明与先前以及当前光照均实现同步化，最终与当前光照实现同步化。因此，在限制进食的仓鼠中，作为Tc和活动节律的同步因子，光照刺激比可预测的进食时间更为重要。
