Restricted‐feeding‐induced anticipatory activity rhythm is associated with a phase‐shift of the expression of mPer1 and mPer2 mRNA in the cerebral cortex and hippocampus but not in the suprachiasmatic nucleus of mice

Abstract

Daily restricted feeding (RF) can produce food-entrainable oscillations in both intact and suprachiasmatic nucleus (SCN)-lesioned animals. Thus, there are two circadian rhythms, one of which is SCN-dependent and the other SCN-independent. Recently, it has been established that several mouse clock genes, such as mPer1, mPer2 and mPer3 are expressed in the SCN and other brain tissues. Although the role of mPer genes expressed in the SCN has recently been evaluated in the SCN-dependent rhythm, their function in the SCN-independent rhythm is still poorly understood. In order to understand the role of these genes in SCN-independent rhythm, we examined the expression pattern of mPer1 and mPer2 mRNA in each brain area of mice under RF. Mice were allowed access to food for 4 h during either the daytime under a light-dark cycle or the subjective daytime under constant dark. After 6 days of scheduled RF, the night-time or subjective night-time peak of mPer mRNA changed to a daytime peak in the cerebral cortex and hippocampus, with moderate expression in the striatum, pyriform cortex and paraventricular nucleus, and no expression in the SCN. The daytime peak in the cerebral cortex returned to a night-time peak after the release of RF to a free-feeding schedule. Although the basal rhythm of mPer expression disappeared in SCN-lesioned mice, RF produced mPer mRNA rhythm in the cerebral cortex of these mice. The present results provide evidence of an association between food-entrainable oscillations and the expression of mPer1 and mPer2 in the cerebral cortex and hippocampus.

Forebrain oscillators ticking with different clock hands

“…In CA1 and DG, HF produced a phase-advance of PER1 IR in keeping with previous studies on Per1 mRNA (Wakamatsu et al, 2001) as well as on PER1 levels in food-restricted rats (AngelesCastellanos et al, 2007). This shifting effect (3 h) for PER1…”

“…The PVN plays an important role in feeding behavior (Sahu, 2004). Moreover, expression of clock genes and c-FOS in this region is altered during restricted feeding (Wakamatsu et al, 2001;Angeles-Castellanos et al, 2004). LCMRglc in the PVN was found to be specifically affected during food-anticipatory activity in HF rats (Pereira de Vasconcelos et al, 2006).…”

“…For instance, rhythmic expression of Per1 and Per2 mRNA is observed in forebrain structures such as olfactory bulbs, piriform and cerebral cortices, hippocampus, paraventricular and arcuate hypothalamic nuclei (Asai et al, 2001;Wakamatsu et al, 2001;Abe et al, 2002;Granados-Fuentes et al, 2004). PER2 expression has also been reported in limbic structures, such as amygdala and bed nucleus of the stria terminalis (Amir et al, 2004;Lamont et al, 2005).…”

“…Whereas light is the principal synchronizer for the SCN, Per oscillations in extra-SCN brain regions can be affected by feeding cues (Wakamatsu et al, 2001;Lamont et al, 2005;AngelesCastellanos et al, 2007). Restricted feeding can produce changes in physiology and behavior which are even more marked in response to hypocaloric feeding (HF) (Challet et al, 2003;Mendoza et al, 2005b;Feillet et al, 2006).…”

Night-time restricted feeding normalises clock genes and Pai-1 gene expression in the db/db mouse liver

“…RF experimentation was performed as previously described [23] with the exception that food could only be accessed for 4 h during the night. In brief, after 1 day of fasting (termed day 0), mice were allowed access to food for 4 h from ZT 18 to ZT 22 for 6 consecutive days (day 1 to day 6) or 12 consecutive days (day 1 to day 12).…”