The Estrous Cycle Coordinates the Circadian Rhythm of Eating Behavior in Mice

The eating behavior rhythm amplitude of female mice peaks primarily during proestrus or estrus, coinciding with elevated estrogen levels.

• Estrous cycle stages were determined by vaginal cytology in female C57BL/6J mice, which exhibited regular 4- to 5-day cycles.
• The greatest number of wheel revolutions occurred on the night of proestrus into estrus when estrogen levels peak.
• The amplitude of the eating behavior rhythm fluctuated with the estrous cycle but did not correlate with the phases of the cycle.
• After ovariectomy, the eating behavior rhythm amplitude fluctuated at irregular intervals, indicating a disruption in hormone regulation.
• In constant darkness, the circadian eating behavior rhythm amplitude peaked every 4 or 5 days, aligning with the phase of proestrus.

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