Circadian patterning of feeding, drinking and activity during diurnal food access in rats
Author: Spiteri, NJ
Physiology and Behavior 28:139-147.
HERO ID: 196363
Using an "ecologically" relevant approach, the present study investigated (1) the association between . . .
Using an "ecologically" relevant approach, the present study investigated (1) the association between feeding and drinking patterns and their circadian organization and (2) changes in general activity (or life-style), during ad lib conditions (fa:LD) and in a situation where access to food was restricted to the light phase (fa:L). Rats were housed in large outcages with nest boxes. Feeding, drinking, activity, outcage and nest occupation were recorded automatically throughout the day-night cycle. Access to food was restricted by a sliding door situated in front of the food hopper. Under ad lib conditions rats were mainly nocturnal, eating 94% and drinking 95% of their daily intakes at night. The patterns of food and water intake were similar, showing a bimodal distribution over the dark phase. During fa:L rats showed an initial large peak in feeding with lights on, followed by a long pause. Thereafter, feeding activity was variable but remained at a low level. The nocturnal drinking pattern persisted. However, 17.5% of daily water intake was meal-associated, compared with 71% during ad lib. Diurnal activity was associated with feeding and nocturnal activity with drinking. Nocturnal outcage and nest occupation patterns were not shifted to the light phase. The experiment demonstrates that rats on an fa:L schedule reduce food and water intake, and body weight, while still retaining circadian characteristics in the temporal distribution of drinking, activity, outcage and nest occupation. Further, although feeding and drinking may be causally related they need not occur in close temporal association. The rapidity of re-establishment of the normal feeding pattern, on return to free-feeding, and the close association with drinking under normal conditions, suggest the existence of a single or two coupled oscillators controlling feeding and drinking.