Document Detail

Bed nucleus of the stria terminalis alpha(1)-adrenoceptor modulates baroreflex cardiac component in unanesthetized rats.
MedLine Citation:
PMID:  18950605     Owner:  NLM     Status:  MEDLINE    
The bed nucleus of stria terminalis (BST) has a tonic modulating role on the baroreflex parasympathetic component. In the present study, we verified that local BST-adrenoceptors modulate baroreflex-evoked bradycardiac responses in unanesthetized rats. Bilateral microinjection of the selective alpha(1)-adrenoceptor antagonist WB4101 (15 nmol/100 nL) into the BST increased the gain of reflex bradycardia in response to mean arterial pressure increases caused by intravenous (i.v.) infusion of phenylephrine, suggesting that BST alpha(1)-adrenoceptors modulate baroreflex bradycardiac response. Bilateral microinjection of either the selective alpha(2)-adrenoceptor antagonist RX821002 (15 nmol/100 nL) or the non-selective beta-adrenoceptor antagonist propranolol (15 nmol/100 nL) into the BST had not affected baroreflex bradycardia. Animals were pretreated intravenously with the cholinergic muscarinic receptor antagonist homatropine methyl bromide (HMB, 1.5 mg/Kg) to test the hypothesis that activation of alpha(1)-adrenoceptors in the BST would modulate the baroreflex parasympathetic component. Baroreflex bradycardiac responses evoked before and after BST treatment with WB4101 were no longer different when rats were pretreated with HMB. These results suggest that parasympathetic activation accounts for the effects saw after BST pharmacological manipulation and ruling out the possibility of a sympathetic withdraw. In conclusion, our data point out that local alpha(1)-adrenoceptors mediate the BST tonic influence on the baroreflex bradycardiac response modulating parasympathetic cardiac activity.
Carlos C Crestani; Fernando H F Alves; Leonardo B M Resstel; Fernando M A Correa
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-10-11
Journal Detail:
Title:  Brain research     Volume:  1245     ISSN:  1872-6240     ISO Abbreviation:  Brain Res.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-11-25     Completed Date:  2009-03-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  108-15     Citation Subset:  IM    
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes 3900, 14049-900 Ribeirão Preto, São Paulo 14090-090, Brazil.
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MeSH Terms
Adrenergic alpha-Antagonists / administration & dosage,  toxicity
Baroreflex / drug effects,  physiology*
Blood Pressure / drug effects,  physiology
Bradycardia / chemically induced,  physiopathology
Dioxanes / administration & dosage,  pharmacology
Heart Rate / drug effects,  physiology
Parasympathetic Nervous System / drug effects,  physiology*
Rats, Wistar
Receptors, Adrenergic, alpha / metabolism,  physiology*
Septal Nuclei / cytology,  drug effects,  physiology*
Tropanes / administration & dosage,  toxicity
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Dioxanes; 0/Receptors, Adrenergic, alpha; 0/Tropanes; 613-67-2/(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; 80-49-9/homatropine methylbromide

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