Changes in eating and daily body temperature are linked to shifts in timing, but not strength, of internal clock gene activity in rats' main brain clock

Body temperature amplitude was decreased by 0.1 °C in rats on a high energy cafeteria diet compared to those on a standard diet.

• Calorie restriction increased body temperature amplitude by 0.3 °C compared to standard diet rats.
• Expression levels of the heat shock protein Hsp90aa1 were lowest in rats on a high energy cafeteria diet and highest in calorie restricted rats.
• No significant changes were observed in the amplitude of clock gene expression or heat shock factor expression across different diets.
• Calorie restriction resulted in phase advances of body temperature, Bmal1, and Per2 rhythms, while high energy cafeteria feeding showed no significant phase changes.
• The suprachiasmatic nucleus may be largely resistant to changes in body temperature rhythm induced by energy intake, with some potential for phase adjustments.

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