Daily cycles of PERIOD1 protein in the brain's food-timing center without expected food-driven activity in rats

Food availability restricted to a single time of day can induce circadian rhythms of clock gene expression in the dorsomedial hypothalamic nucleus (DMH) in rodents.

• Rats showed increased activity during the unpredictable times when food was presented, but did not develop anticipatory behavior linked to a specific meal time.
• Clock protein expression, Period1 (PER1), in the suprachiasmatic nucleus (SCN) was unaffected by variable restricted feeding (VRF) schedules.
• In the DMH, PER1 expression became rhythmic when food was available only during the day or night, peaking at opposite times.
• When food was presented randomly throughout the 24-hour cycle, PER1 expression in the DMH remained arrhythmic but elevated.
• The findings suggest that while feeding schedules can alter clock gene expression rhythms, they do not synchronize behavioral rhythms.

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