CIRCADIAN-RHYTHMS OF FOOD AND WATER-INTAKE AND URINE EXCRETION IN DIABETIC RATS

The light/dark (L/D) rhythms of food and water intake and urine output were studied in normal and diabetic rats for 7 consecutive days at 4- h intervals. The control rats showed the highest values of these param eters during the dark phase (83.68% food, 68.7 1 % water, and 67.44% u rine). The diabetic rats also maintained this nocturnal predominance, although the values were less marked (59.55% food, 55% water, and 56% urine). A circadian rhythm of food (phi = 3.31 h) and water (phi = 3.5 4 h) intake as well as of the volume of urine excreted (phi = 1.10) wa s detected in the control animals. The diabetic rats, in spite of pres enting polyphagia, maintain the circadian rhythm of food intake, where as a loss of the normal circadian variation of drinking intake was obs erved as well as the absence of circadian rhythm in urinary excretion. It was concluded that in streptozotocin-diabetic rats we have observe d a loss of the normal patterns of water intake and urinary excretion, perhaps masked by the polydipsia and polyuria, whereas the circadian rhythm of food intake remains.