Altered energy intake and the amplitude of the body temperature rhythm are associated with changes in phase, but not amplitude, of clock gene expression in the rat suprachiasmatic nucleus in vivo

In vitro , temperature cycles within the physiological range can act as potent entraining cues for biological clocks. We altered the body temperature (T c ) rhythm in rats by manipulating energy intake (EI) to determine whether EI-induced changes in T c oscillations are associated with changes in SCN clock gene rhythms in vivo .

Male Wistar rats ( n = 16 per diet) were maintained on either an ad libitum diet (CON), a high energy cafeteria diet (CAF), or a calorie restricted diet (CR), and T c was recorded every 30 min for 6-7 weeks. SCN tissue was harvested from rats at zeitgeber time (ZT) 0, ZT6, ZT12, or ZT18. Expression of the clock genes Bmal1, Per2, Cry1 , and Rev-erbα , the heat shock transcription factor Hsf1 , and the heat shock protein Hsp90aa1 , were determined using qPCR.