The acrophase of Per2 expression is differentially affected in the SCN and the VMH of Sf1-cre;Sirt1loxP/loxP mice by food restriction in constant darkness. Black symbols, Sirt1loxP/loxP; red symbols, Sf1-Cre;Sirt1loxP/loxP; circles, SD; triangles, HF diet. Blue rectangle denotes the meal period. A, In the SCN, the acrophase of Per2 shows a phase delay in the Sf1-Cre;Sirt1loxP/loxP compared with the Sirt1loxP/loxP mice under DD, food restriction, and HF diet. Comparing the effects by experimental condition, the DD affects the Sf1-Cre;Sirt1loxP/loxP mice more than Sirt1loxP/loxP mice. B, In the VMH, the same conditions provoke a phase advance in the acrophase in the Sf1-Cre;Sirt1loxP/loxP mice. Food restriction slightly affects the Sf1-Cre;Sirt1loxP/loxP mice, whereas Sirt1loxP/loxP mice are strongly affected by this condition. *, P < .05, **, P < .01, ***, P < .001, t test (n = 6 animals per group).