Document Detail


Catecholamine and blood pressure regulation by gonadotropin-releasing hormone analogs in amphibians.
MedLine Citation:
PMID:  3130174     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Analogs of gonadotropin-releasing hormone (GnRH) occur in the brain, plasma, and sympathoadrenal system of anuran amphibians. The present experiments studied the effects of GnRH and [Trp7, Leu8]-GnRH on plasma catecholamines and cardiovascular function in conscious adult bullfrogs (Rana catesbeiana) and cane toads (Bufo marinus). Both GnRH analogs elicited dose-dependent (0.1-1 nmol.kg-1) increases in arterial norepinephrine, epinephrine, and blood pressure levels when injected intravenously into toads. In bullfrogs, [Trp7, Leu8]-GnRH (1 nmol.kg-1) increased arterial norepinephrine concentration approximately 10-fold without affecting the concentrations of norepinephrine sulfate, norepinephrine glucuronide, epinephrine, epinephrine sulfate, or epinephrine glucuronide. The noradrenergic response of bullfrogs to [Trp7, Leu8]-GnRH was specific to the neurohormone because it could be inhibited by [D-pGlu1, D-Phe2, D-Trp3,6]-GnRH. The sympathomimetic activities of the GnRH analogs did not depend on changes in temperature, which occur seasonally in natural habitats, because similar noradrenergic responses were observed at 4 and 22 degrees C. GnRH and [Trp7, Leu8]-GnRH (0.01-10 nmol.kg-1) did not raise arterial blood pressure in bullfrogs despite their pressor actions in toads. This interspecific difference was remarkable because cardiovascular responses to norepinephrine, angiotensin II, and vasotocin in bullfrogs were similar to those in toads. The parallels between catecholamine and blood pressure responses suggest that epinephrine is the principal mediator of the blood pressure response to native GnRH analogs in toads. In bullfrogs, [Trp7, Leu8]-GnRH mobilizes norepinephrine but not epinephrine, and the noradrenergic effect is insufficient to raise blood pressure. These observations are consistent with a physiological role for native GnRH analogs in the regulation of the sympathoadrenal system in anuran amphibians.
Authors:
J X Wilson; K J Saleh; E D Armogan; E J Jaworska
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  65     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1987 Dec 
Date Detail:
Created Date:  1988-06-20     Completed Date:  1988-06-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  2379-85     Citation Subset:  IM    
Affiliation:
Department of Physiology, University of Western Ontario, London, Canada.
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MeSH Terms
Descriptor/Qualifier:
Angiotensin II / pharmacology
Animals
Blood Pressure* / drug effects
Bufo marinus
Cardiac Output / drug effects
Catecholamines / physiology*
Epinephrine / blood,  pharmacology
Norepinephrine / blood,  pharmacology
Pituitary Hormone-Releasing Hormones / blood,  physiology*
Rana catesbeiana
Vasotocin / pharmacology
Chemical
Reg. No./Substance:
0/Catecholamines; 0/Pituitary Hormone-Releasing Hormones; 11128-99-7/Angiotensin II; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 9034-50-8/Vasotocin

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


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