Figure 7. Intact FAA in Bmal1 brain knockout mice.
(A) Schedule of a gradual temporal FR protocol in LD (upper) or DD (lower). Horizontal black and white bars represent lights off and on, respectively. Gray bars represent food availability. Since abrupt shifts to FR can have a high morbidity in mice, a gentle temporal FR paradigm was used (FR ramp), decreasing the duration of daily food availability from constant to a final 4 hr window over the course of 5 days. Because free-running in DD can obscure FAA in control mice, we obtained DD baseline activity and then switched mice to 14 days of LD (not shown). We then transferred our mice directly from LD into DD FR following an LD food ramp (lower). It should be noted that once gradual FR began, the time of onset of food availability was the same each day. (B, F) Representative double-plotted actograms of daily wheel-running activity of 3 Fx/Fx control littermates and 3 BKO mice during ad lib feeding and under subsequent FR during LD (B) or DD (F). The boxed area toward the left side of each actogram indicates the daily interval of food availability under FR and yellow areas indicate time of lights-on during LD 12:12. After 5 days of gradually decreasing food availability, the final food availability window was ZT/CT6–10. For clarity, the 5-day FR ramp is not included in the boxed area (B). (C, G) Mean locomotor activity profiles of Fx/Fx littermates (n = 7) and BKO mice (n = 14) under ad lib feeding (left) and during FR days 8–14 (right) under LD (C) or DD (G). Each data point represents counts per minute averaged for each genotype across a 6-min bin (±SEM). The dashed boxed area (left) indicates, for comparison, the daily interval corresponding to subsequent food availability. The solid boxed area (right) indicates the daily interval of food availability under FR. (D, H) Time course of the development of FAA in Fx/Fx controls (n = 7) and BKO mice (n = 14) during LD FR (D) or DD FR (H). FAA is plotted as the total number of activity counts (mean ± SEM) allocated to a 6-hr time interval prior to mealtime, ZT/CT0–6 (D, H). (E) Number of hours by which FAA preceded daily meal times in Fx/Fx (n = 7) and BKO mice (n = 14) during LD FR. Wheel-running activity profiles were averaged for each individual during stable FR (as in C), and the average time of onset of FAA was determined as the time before food availability at which FAA rose to its half-maximum value (mean ± SEM). (I) Quantification of FAA under DD conditions in BKO mice (n = 14). Plotted is fold-change of wheel-running activity (counts per minute, mean ± SEM) in each mouse for CT0–6 (window of FAA) compared with CT10–24 (the rest of the day except for the window of food availability). During FR, increased locomotor activity during CT0–6 compared with CT10–24 was highly significant (*p = 0.0001 by paired t-test).
Figure 7—figure supplement 1. Lack of Bmal1 expression in the DMH of Bmal1 brain knockout mice.
