Figure 5.

Entrainment of behavior and clock gene expression to an RF schedule in Vipr2^−/− mice. A, B, Representative profiles of locomotor activity in wild-type (A) and Vipr2^−/− (B) mice are presented in double-plotted format. After an initial period of entrainment to an LD cycle with ad libitum access to food (LD; days 1–4), food availability was reduced to 4 h/d (A, B, boxed regions; from 11:00 A.M. to 3:00 P.M.), initially in an LD cycle (LD-RF; days 5–21) and subsequently in DD (DD-RF; days 22–34). Ad libitum access to food was then restored (DD; days 35–43). C, D, Cumulative wheel running counts were monitored under an RF schedule in wild-type (black bars) and Vipr2^−/− (gray bars) mice over 4 h periods for 48 h in LD (C) or 2 d after transfer into DD (D). E, F, Rhythms of Per1 gene expression in the liver of wild-type (filled squares) and Vipr2^−/− (open squares) mice under an RF schedule were measured by TaqMan RT-PCR in LD (E) or 2 d after transfer into DD (F). One 24 h set of data has been plotted twice to better show the pattern of variation with time. C–F, The bars at the top indicate the dark period in black and the light period in white (C, E) or subjective night in black and subjective day in gray (D, F). The period of food availability in C–F is indicated by a striped bar. Values represent mean ± SEM.