Ghrelin Stimulates Feeding, Inhibits Water Intake in Rats

Antidipsogenic effect comparable to atrial natriuretic peptide

FRIDAY, April 20 (HealthDay News) -- The neuropeptide ghrelin is a potent stimulator of feeding in mammals, and a new study suggests it also inhibits water consumption in rats when administered centrally or peripherally. The findings are published in the April issue of Endocrinology.

Yoichi Ueta, M.D., Ph.D., of Kitakyushu, Japan, and colleagues injected up to 10 nmol ghrelin intravenously or intracerebrovascularly into 24-hour water-deprived rats and measured food intake, water intake, and urine volume after reintroduction of food and water.

Intracerebrovascular injection of ghrelin potently stimulated food intake while causing a dose-dependent reduction in water intake and urine volume compared to controls. The effect on water intake was comparable to that observed with atrial natriuretic peptide, the most potent antidipsogen known so far. The authors linked the effects of ghrelin to changes in neuronal Fos expression in the area postrema and the nucleus of the tractus solitarius.

The simultaneous orexigenic and antidipsogenic effect of ghrelin is "puzzling," because most water-drinking is temporarily associated with feeding, the authors said. "The central mechanism of the action of ghrelin for inhibiting drinking should be clarified in relation to the induction of feeding in rats," they said.

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