Sánchez-Vázquez F J, Aranda A, Madrid J A
Department of Physiology & Pharmacology, Faculty of Biology, University of Murcia, Spain.
J Biol Rhythms. 2001 Feb;16(1):58-65. doi: 10.1177/074873040101600107.
The synchronizing stimulus, its transduction site, and the afferent pathways responsible for feeding entrainment remain unknown. In fish, the role of the diet in the development of feeding anticipatory activity (FAA) is not well understood and fundamental questions on the mechanisms of feeding entrainment, such as the meal characteristics required to develop FAA, remain unexplored. To test the entraining properties of daily meals with different sizes and energy densities, activity rhythms were studied after a 12-h shift of the feeding cycle in individual goldfish under constant light. In the 1st experiment, the energy content of a control diet (16.7 kJ/g) was diluted by replacing 50% (8.3 kJ/g) or 90% (1.7 kJ/g) of the diet with cellulose. However, the number of days required to stabilize FAA after the shift did not differ statistically between diets. In the 2nd experiment, meal size was modified by reducing the daily feeding ration to 0.5% and 0.1% b.wt.d(-1). In this case, differences in the entraining properties of the two feeding rations appeared because goldfish fed at 0.1% b.wt.d(-1) resynchronized faster than those fed at 0.5% b.wt.d(-1). These results revealed that the dilution of the dietary energy up to 1.7 kJ/g had no significant effect on the entraining properties of the feeding-entrainable oscillator (FEO), whereas the reduction of the meal size to 0.1% b.wt.d(-1) provoked a faster resynchronization after shifting the daily meal cycle. Taken together, these results suggest that gut distension may be involved in feeding entrainment, as a reduction in meal size but not in the amount of dietary energy supplied significantly shortened the time required for resynchronization and highlighted the different synchronizing properties of meal size and energy density as zeitgebers for the FEO.
同步刺激、其转导位点以及负责进食夹带的传入通路仍不清楚。在鱼类中，饮食在进食预期活动（FAA）发展中的作用尚未得到充分理解，关于进食夹带机制的基本问题，如发展FAA所需的进餐特征，仍未得到探索。为了测试不同大小和能量密度的日常餐食的夹带特性，在恒定光照下，对个体金鱼的进食周期进行12小时的调整后，研究了其活动节律。在第一个实验中，通过用纤维素替代50%（8.3 kJ/g）或90%（1.7 kJ/g）的对照饮食（16.7 kJ/g）来稀释饮食能量。然而，饮食调整后FAA稳定所需的天数在不同饮食之间没有统计学差异。在第二个实验中，通过将每日喂食量减少到0.5%和0.1%体重·天⁻¹来改变餐食大小。在这种情况下，两种喂食量的夹带特性出现了差异，因为以0.1%体重·天⁻¹喂食的金鱼比以0.5%体重·天⁻¹喂食的金鱼重新同步得更快。这些结果表明，饮食能量稀释至1.7 kJ/g对可进食夹带振荡器（FEO）的夹带特性没有显著影响，而将餐食大小减少到0.1%体重·天⁻¹会在每日餐食周期改变后引发更快的重新同步。综上所述，这些结果表明肠道扩张可能参与进食夹带，因为餐食大小的减少而非供应的饮食能量的减少显著缩短了重新同步所需的时间，并突出了餐食大小和能量密度作为FEO的授时因子的不同同步特性。
