Effects of disruption of diurnal rhythms in food intake of rats.

The calorie intake, body weight (bw) maintenance and oral intake of ad lib fed (Gr I) and feeding rhythm-disrupted (Gr II) adult rats of either sexes are investigated. Gr I calorie intake (19.2 +/- 0.6 cal/100 gm bw) and bw (214 +/- 5.6 gms) were stabilized after 130-140 days of age. Rats of similar age (130-140 days) on feeding rhythm disruption (Gr II) showed initial decrease in calorie intake and bw but 136 days later their bw (224 +/- 6.5 gms) was similar to Gr I bw (226 +/- 9.2 gms) though calorie intake (17.5 +/- 0.4 cal/100 gm bw) was still less as compared Gr I intake. This disparity in calorie intake and bw in Gr II appears to be linked to the adaptive metabolic changes. The solution and mixed-diets tests showed that oral intake is taste-dependent in Gr II but not in Gr I. Gr II intake was increased on sweet taste and decreased on salt and bitter tastes indicating that feeding rhythm-disruption enhances sensory regulation of intake in contrast to calorie regulation found predominant on free feeding.