Region-specific modulation of PER2 expression in the limbic forebrain and hypothalamus by nighttime restricted feeding in rats

Jun 11, 2008Neuroscience letters

Nighttime limited feeding changes PER2 levels in emotion and hormone control brain areas of rats

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Abstract

Nighttime restricted feeding shifts the rhythm of PER2 expression in the BNSTov and central nucleus of the amygdala (CEA) approximately 12 hours after mealtime.

Nighttime restricted feeding, similar to daytime restricted feeding, induces changes in the rhythm of the clock protein PER2 in specific brain regions.
Shifts in PER2 expression in the BNSTov and CEA occur without affecting the rhythm in the suprachiasmatic nucleus (SCN).
Nighttime restricted feeding also induces a rhythm of PER2 expression in the dorsomedial hypothalamic nucleus (DMH).
In contrast to daytime feeding studies, nighttime restricted feeding does not affect PER2 rhythms in the basolateral amygdala (BLA) or dentate gyrus (DG).
Nighttime restricted treats do not influence PER2 expression in any of the brain areas studied.

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Feeding schedules that restrict food access to a predictable daytime meal induce in rodents food-anticipatory behaviors, changes in physiological rhythms and shifts in the rhythm of clock gene expression in the brain and periphery. However, little is known about the effects of nighttime restricted feeding. Previously, we showed that daytime restricted access to a highly palatable complete meal replacement, Ensure Plus (Ensure), shifts the rhythm of expression of the clock protein PER2 in limbic forebrain areas including the oval nucleus of the bed nucleus of the stria terminalis (BNSTov), central nucleus of the amygdala (CEA), basolateral amygdala (BLA) and dentate gyrus (DG), and induces a rhythm in the dorsomedial hypothalamic nucleus (DMH) in food deprived (restricted feeding), but not free-fed rats (restricted treat). In the present study we investigated the effects of nighttime restricted feeding (Ensure only, 2 h/night) and nighttime restricted treats (Ensure 2 h/night+free access to chow) in order to determine whether these effects were dependent on the time of day the meal was provided. We found that nighttime restricted feeding, like daytime restricted feeding, shifted the rhythm of PER2 expression in the BNSTov and CEA and peak expression was observed approximately 12 h after the mealtime. Also consistent with previous work, nighttime restricted feeding induced a rhythm of PER2 expression in the DMH and these effects occurred without affecting the rhythm in the suprachiasmatic nucleus (SCN). In contrast to previous work with daytime restricted feeding, nighttime restricted feeding had no effect on PER2 rhythms in the BLA and DG. Finally, nighttime restricted treats, as was the case for daytime restricted treats, had no effect on PER2 expression in any of the brain areas studied. The present results together with our previous findings show that the effect of restricted feeding on PER2 rhythms in the limbic forebrain and hypothalamus depend on a negative energy balance and vary as a function of time of day in a brain region-specific manner.

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Region-specific modulation of PER2 expression in the limbic forebrain and hypothalamus by nighttime restricted feeding in rats

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