Neurogenetics of food anticipation

Abstract

Circadian clocks enable the organisms to anticipate predictable cycling events in the environment. The mechanisms of the main circadian clock, localized in the suprachiasmatic nuclei of the hypothalamus, involve intracellular autoregulatory transcriptional loops of specific genes, called clock genes. In the suprachiasmatic clock, circadian oscillations of clock genes are primarily reset by light, thus allowing the organisms to be in phase with the light-dark cycle. Another circadian timing system is dedicated to preparing the organisms for the ongoing meal or food availability: the so-called food-entrainable system, characterized by food-anticipatory processes depending on a circadian clock whose location in the brain is not yet identified with certainty. Here we review the current knowledge on food anticipation in mice lacking clock genes or feeding-related genes. The food-entrainable clockwork in the brain is currently thought to be made of transcriptional loops partly divergent from those described in the light-entrainable suprachiasmatic nuclei. Possible confounding effects associated with behavioral screening of meal anticipation in mutant mice are also discussed.

Caloric restriction

“…Rats that received 50% restriction as two meals/day had significantly more adipose tissue mass than the other restricted groups. One reason why this effect may happen is that when CR animals are fed a single meal they show a large amount of anticipatory activity in the period prior to the meal arriving (Challet et al, 2009;Mistlberger, 1994) and they subsequently eat the meal rapidly. It has been shown that there is a correlation between anticipatory activity and how fast the food is eaten, suggesting both are perhaps driven by the experience of hunger.…”

Bmal1in the Nervous System Is Essential for Normal Adaptation of Circadian Locomotor Activity and Food Intake to Periodic Feeding

“…However, the anatomical substrate(s) and molecular machinery of the so-called "food-entrainable oscillator (FEO)" remains to be unknown. Moreover, despite the well characterized circadian nature of FAA, the involvement of canonical clock genes remains controversial (Challet et al, 2009). For example, one study demonstrated that arrhythmic Bmal1 Ϫ/ Ϫ mice also lack food-entrainable circadian rhythms (Fuller et al, 2008), while another two studies reported normal FAA of the same mouse line (Pendergast et al, 2009;Storch and Weitz, 2009).…”

Influence of defensible and indefensible pattern of food delivery upon the development of feeding anticipatory activity (FAA) and growth performance in rainbow trout (Oncorhynchus mykiss)

“…Mammals (rodents) possess an endogenous circadian clock known as light-entrainable oscillator (LEO) which is synchronised by photoperiodic signals. It is thought that rodents' LEO is localised in the suprachiasmatic nucleus (SCN) of the hypothalamus (Stephan and Zucker, 1972;Moore and Eichler, 1977;Landry et al, 2007;Caba et al, 2008;Challet et al, 2009), synchronising light-related rhythms. In fish, little is known on this topic (Sanchez-Vazquez et al, 1995b), but in most fishes a circadian rhythm of locomotor activity has been proposed which appears to be feeding-entrained (Kavaliers, 1979(Kavaliers, , 1980Tabata et al, 1989;Azzaydi et al, 2007).…”