Lack of Food Anticipation in Per2 Mutant Mice

Abstract

Predicting time of food availability is key for survival in most animals. Under restricted feeding conditions, this prediction is manifested in anticipatory bouts of locomotor activity and body temperature. This process seems to be driven by a food-entrainable oscillator independent of the main, light-entrainable clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus . Although the SCN clockwork involves self-sustaining transcriptional and translational feedback loops based on rhythmic expression of mRNA and proteins of clock genes , the molecular mechanisms responsible for food anticipation are not well understood. Period genes Per1 and Per2 are crucial for the SCN's resetting to light . Here, we investigated the role of these genes in circadian anticipatory behavior by studying rest-activity and body-temperature rhythms of Per1 and Per2 mutant mice under restricted feeding conditions. We also monitored expression of clock genes in the SCN and peripheral tissues. Whereas wild-type and Per1 mutant mice expressed regular food-anticipatory activity, Per2 mutant mice did not show food anticipation. In peripheral tissues, however, phase shifts of clock-gene expression in response to timed food restriction were comparable in all genotypes. In conclusion, a mutation in Per2 abolishes anticipation of mealtime, without interfering with peripheral synchronization by feeding cycles.

Systems approach identifies an organic nitrogen-responsive gene network that is regulated by the master clock control gene CCA1

“…Our study thus provides evidence that plant nutrition, like in animals, is tightly linked to circadian functions as previously hypothesized (19). Recently, it was shown that the central clock gene Per2 is necessary for food anticipation in mice (33). Our data indicate that the central clock gene CCA1 plays a role in circadian regulation of Nassimilation in plants.…”

The daily rhythm of mice

“…Hence, the circadian clock might also be important to predict food availability in mammals. In line with this hypothesis is the finding that mice with a mutation in the Per2 gene do not have food anticipatory activity (FAA) and temperature increase [75] indicating that PER2 is involved in food anticipation either in its function as a clock gene or via a clock-independent mechanism. Although other clock components such as NPAS2 or Mop3/BMAL1 show reduced food anticipation [19] recent experiments suggest that daily rhythms of FAA do not require the circadian clock [76].…”

The Cerebellum Harbors a Circadian Oscillator Involved in Food Anticipation

“…To study the rhythmic expression of clock genes in the cerebellum, mice under a light-dark cycle (LD) were used under two different feeding conditions. A group had free access to food (food ad libitum, AL), while another group (hypocaloric feeding: HF) was submitted to a temporal calorie restriction paradigm, in which animals received the 66% of daily food intake at midday [Zeitgeber time (ZT)6] for at least 3 weeks as described previously (Mendoza et al, 2005a;Feillet et al, 2006). On the last day of food restriction, mice were killed with isoflurane overdose and decapitated in 8 groups of 4 mice, at 3 h intervals starting at ZT0.…”