Influence of scheduled restricted feeding on reentrainment of motor activity rhythm after a 6-h light-dark advance in rats

ABSTRACT

Circadian rhythms are entrained to cyclic environmental cues such as the light-dark cycle and food availability. The suprachiasmatic nucleus of the hypothalamus is the main circadian oscillator in mammals and is entrained primarily by the light-dark cycle, although in some experimental situations food availability can affect its oscillation. Here we tested whether scheduled restricted feeding is capable of influencing the reentrainment of the motor activity rhythm (i.e., a behavioral rhythm controlled by the suprachiasmatic nucleus) to a 6-h phase advance of the light-dark cycle. Rats were housed in a standard 12 h:12 h light-dark cycle for 18 days, and then the time of lights-off was advanced. Rats subjected to scheduled restricted feeding starting on the first day of the light-dark shift showed faster reentrainment of the motor activity rhythm compared with control rats maintained with ad libitum food. The results showed that scheduled feeding effectively accelerates reentrainment of a behavioral circadian rhythm and suggest that the procedure may affect activity in the suprachiasmatic nucleus during the stage of reentrainment to light-dark shifts.