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 parameters during the dark phase (83.68% food, 68.71% water, and 67.44% urine). 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 = 3.54 h) intake as well as of the volume of urine excreted (phi = 1.10) was detected in the control animals. The diabetic rats, inspite of presenting polyphagia, maintain the circadian rhythm of food intake, whereas a loss of the normal circadian variation of drinking intake was observed as well as the absence of circadian rhythm in urinary excretion. It was concluded that in streptozotocin-diabetic rats we have observed 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.
Velasco Plaza
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Department of Physiology, Faculty of Medicine, University of Oviedo, Spain.
G-Granda
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Cachero
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D000818:Animals; D001835:Body Weight / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000523:psychology*; D004326:Drinking / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014554:Urination / Q000502:physiology*