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Glucocorticoids increase salt appetite by promoting water and sodium excretion
Journal article   Open access   Peer reviewed

Glucocorticoids increase salt appetite by promoting water and sodium excretion

Robert L Thunhorst, Terry G Beltz and Alan Kim Johnson
American journal of physiology. Regulatory, integrative and comparative physiology, Vol.293(3), pp.R1444-1451
09/2007
DOI: 10.1152/ajpregu.00294.2007
PMCID: PMC2922067
PMID: 17596327
url
https://doi.org/10.1152/ajpregu.00294.2007View
Published (Version of record) Open Access

Abstract

Glucocorticoids [e.g., corticosterone and dexamethasone (Dex)], when administered systemically, greatly increase water drinking elicited by angiotensin and sodium ingestion in response to mineralocorticoids [e.g., aldosterone and deoxycorticosterone acetate (DOCA)], possibly by acting in the brain. In addition, glucocorticoids exert powerful renal actions that could influence water and sodium ingestion by promoting their excretion. To test this, we determined water and sodium intakes, excretions, and balances during injections of Dex and DOCA and their coadministration (DOCA+Dex) at doses commonly employed to stimulate ingestion of water and sodium. In animals having only water to drink, Dex treatment greatly increased water and sodium excretion without affecting water intake, thereby producing negative water and sodium balances. Similar results were observed when Dex was administered together with DOCA. In animals having water and saline solution (0.3 M NaCl) to drink, Dex treatment increased water and sodium excretion, had minimal effects on water and sodium intakes, and was associated with negative water and sodium balances. DOCA treatment progressively increased sodium ingestion, and both water and sodium intakes exceeded their urinary excretion, resulting in positive water and sodium balances. The combination of DOCA+Dex stimulated rapid, large increases in sodium ingestion and positive sodium balances. However, water excretion outpaced total fluid intake, resulting in large, negative water balances. Plasma volume increased during DOCA treatment and did not change during treatment with Dex or DOCA+Dex. We conclude that increased urinary excretion, especially of water, during glucocorticoid treatment may explain the increased ingestion of water and sodium that occurs during coadministration with mineralocorticoids.
 Animals Appetite - drug effects Body Weight - drug effects Desoxycorticosterone - pharmacology Dexamethasone - pharmacology Eating - drug effects Electrolytes - urine Glucocorticoids - pharmacology Male Plasma Volume - drug effects Rats Rats, Sprague-Dawley Sodium - urine Sodium Chloride, Dietary Water - metabolism Water-Electrolyte Balance - drug effects

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