Starvation and respiratory rhythmic behavior in groups of light-dark synchronized Sprague-Dawley rats

Twenty adult male SPF Sprague-Dawley rats, grouped by 5 and synchronized by a light (L)-dark (D) 12:12 alternation, were deprived of food and water for 7 days; 20 other rats were taken as controls. Continuous measurement of emitted carbon dioxide (VCO2), which was taken as an index of respiratory and metabolic exchanges, shows that starvation significantly (p less than 0.001) decreases the amplitudes of the circadian VCO2 rhythms (by 42.5% during L and 35.6% during D) and also the L----D photic VCO2 responses (by 9.2%; p less than 0.05). Concerning ultradian rhythms of mean and great periods (40 min less than tau less than 24 hr), food and water suppression diminishes their amplitudes (by 58.4% in L and 32.4% in D) and changes their phases (by a 1.29 radian advance in L and a 0.68 radian delay in D). Rats recovered their prestarvation circadian and ultradian VCO2 rhythms 6-7 days after food and water had been given back to them.