Potentiation of angiotensin II-induced drinking by glucocorticoids is a specific glucocorticoid type II receptor (GR)-mediated event.
Earlier studies showed that pretreatment (3 and 6 h) of rats with the glucocorticoid hormone, dexamethasone, potentiated the drinking response to either central or peripheral administration of angiotensin II (AII). In the present study the specificity and mechanisms of this potentiation were examined. Intraperitoneal (i.p.) injection of rats with the pure glucocorticoid agonist, RU 28362 (0.4-1.6 mg/kg; 3-24 h), resulted in a time- and dose-dependent potentiation of the drinking responses to either peripherally (100 micrograms/kg, s.c.) or centrally (10 ng) injected AII, similar to the effects of dexamethasone. Drinking induced by central injection of carbachol (200 ng) was unaltered by pretreatment with RU 28362, suggesting that potentiation by this compound was specific for AII. The potentiation of AII-induced drinking by either dexamethasone or RU 28362 was completely abolished by pretreatment with the glucocorticoid Type II receptor (GR) antagonist, RU 38486 (2 mg/kg, i.p.), but not by the mineralocorticoid Type I receptor (MR) blocker, mespirenone (2 mg/kg, i.p.). Taken together, these results indicate that the glucocorticoid-induced potentiation of AII-induced drinking is mediated via GR. Associated with the fact that glucocorticoids potentiate AII-induced drinking is the observation that these steroids also potentiate AII-induced urine output. This enhancement of urine output may explain in part the potentiation in drinking behavior. Possible mechanisms are discussed.
Sumners
C
C
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
Gault
T R
TR
Fregly
M J
MJ
D000732:Androstanols / Q000008:administration & dosage / Q000494:pharmacology*; D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects*; D004357:Drug Synergism; D007276:Injections, Intraventricular; D008297:Male; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D013148:Spironolactone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
D000732:Androstanols; D000451:Mineralocorticoid Receptor Antagonists; D011965:Receptors, Glucocorticoid; D000804:Angiotensin II; D013148:Spironolactone; C049154:11,17-dihydroxy-6-methyl-17-(1-propynyl)androsta-1,4,6-triene-3-one; D003907:Dexamethasone; D002217:Carbachol; C051308:mespirenone