Document Detail

Hypothalamic GABA and sympathetic regulation in spontaneously hypertensive rats.
MedLine Citation:
PMID:  2583798     Owner:  NLM     Status:  MEDLINE    
The posterior hypothalamus contains a sympathoexcitatory system that can be modulated by changes in GABAergic tone. We tested the hypothesis that the GABAergic mechanism in the posterior hypothalamus is altered in spontaneously hypertensive rats (SHR) compared with the Wistar-Kyoto (WKY) control rats. Blood pressure and heart rate were continuously measured in the conscious state; blood samples were obtained for determination of plasma catecholamine concentrations. Bilateral microinjections of the GABAA receptor antagonist bicuculline methiodide into the posterior hypothalamus increased heart rate and blood pressure in a dose-related fashion and increased plasma catecholamine concentrations in both SHR and WKY rats. The responses were not significantly different between the two strains of rats. Microinjections of the GABAA receptor agonist muscimol in this same region caused dose-related decreases in both heart rate and blood pressure in SHR and WKY rats. Although the decreases in heart rate caused by muscimol were not significantly different between the SHR and WKY rats, the decreases in blood pressure were significantly greater in SHR compared with WKY rats. Further, microinjection of muscimol caused a significant decrease in plasma catecholamines in SHR but not in WKY rats. These data indicate that in SHR and WKY rats the posterior hypothalamus contains a sympathoexcitatory mechanism that is tonically inhibited by GABA. The ability of muscimol to decrease plasma catecholamines selectively in SHR and to cause greater decreases in blood pressure, suggests that the GABAergic mechanisms in the posterior hypothalamus of the SHR and WKY rats may differ.
J H Wible; J A DiMicco; F C Luft
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Hypertension     Volume:  14     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:  1989 Dec 
Date Detail:
Created Date:  1990-01-09     Completed Date:  1990-01-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  623-8     Citation Subset:  IM    
Department of Pharmacology, Indiana University School of Medicine, Indianapolis 46202-5120.
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MeSH Terms
Bicuculline / analogs & derivatives*,  pharmacology
Blood Pressure / drug effects*
Catecholamines / blood
Heart Rate / drug effects*
Motor Activity / drug effects
Muscimol / pharmacology
Rats, Inbred SHR
Rats, Inbred WKY
Time Factors
Grant Support
Reg. No./Substance:
0/Catecholamines; 2763-96-4/Muscimol; 40709-69-1/bicuculline methiodide; 485-49-4/Bicuculline

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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