Mammillary polydipsia and diabetes insipidus: a study of the rhythmicity of water intake.
Rats with polydipsia induced by electrolytic mammillary lesions show a normal daily rhythmicity of water intake compared with sham lesioned animals, when kept in a 12:12 hours light-dark cycle of illumination. Water is mainly consumed during the dark phase (approximately 80-90% of the total amount). On the other hand, rats with centrally induced diabetes insipidus by means of electrolytic lesions in the median eminence show a clear-cut alteration in this rhythmicity, drinking only 67% of the total amount during the dark phase. This effect could be due to the continuous necessity of these animals to drink water in order to maintain fluid homeostasis, and is not related to food rhythmicity alterations. Taken together, and on the basis of the daily rhythmicity of water intake, these results suggest that mammillary polydipsia may be different from that observed when diabetes insipidus is present.
Morales
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Departamento de Psicología Experimental y Fisiología del Comportamiento, Universidad de Granada, Spain.
Cubero
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Puerto
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D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000473:pathology; D002940:Circadian Rhythm; D003919:Diabetes Insipidus / Q000503:physiopathology*; D004327:Drinking Behavior / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D008297:Male; D008326:Mammillary Bodies / Q000502:physiology*; D008473:Median Eminence / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013894:Thirst; D013997:Time Factors