Behavioural food anticipation in clock genes deficient mice: confirming old phenotypes, describing new phenotypes

Mice with mutations of clock genes Per1 and Per2 show altered food-anticipatory activity (FAA).

• Single mutations of the clock genes Per1 and Per2 impact FAA expression under both constant darkness and light-dark cycles.
• Double mutant mice lacking both Per1 and Per2 or Per2 and Cry1 do not exhibit stable FAA in either constant darkness or light-dark cycles.
• In a specific double mutant (Per2 and Cry2), behavioral rhythms are fully entrained to mealtime cues in constant darkness, suggesting heightened sensitivity to feeding times.
• Despite this sensitivity in constant darkness, the same double mutant mice do not show FAA under a light-dark cycle with restricted midday feeding.
• These findings indicate that the disruption of one or two clock genes can significantly alter circadian anticipation of meals.

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