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Lateral septal area α1- and α2-adrenoceptors differently modulate baroreflex activity in unanesthetized rats.
MedLine Citation:
PMID:  22179423     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The lateral septal area (LSA) is a limbic structure involved with autonomic, neuroendocrine and behavioral responses. An inhibitory influence of the LSA on baroreflex activity has been reported. However, the local neurotransmitter involved in this modulation is still unclear. In the present study, we verified the involvement of local LSA adrenoceptors in modulating cardiac baroreflex activity in unanesthetized rats. Bilateral microinjection of the selective α1-adrenoceptor antagonist WB4101 (10 nmol/100 nl) into the LSA decreased baroreflex bradycardia evoked by blood pressure increases, but had no effect on reflex tachycardia evoked by blood pressure decreases. Nevertheless, bilateral administration of the selective α2-adrenoceptor antagonist RX821002 (10 nmol/100 nl) increased baroreflex tachycardia without affecting reflex bradycardia. LSA treatment with a cocktail containing WB4101 and RX821002 into the LSA decreased baroreflex bradycardia and increased reflex tachycardia. The non-selective β-adrenoceptor antagonist propranolol (10 nmol/100 nl) did not affect either reflex bradycardia or tachycardia. Microinjection of noradrenaline into the LSA increased reflex bradycardia and decreased baroreflex tachycardic response, an opposed effect compared to those observed after double blockade of α1- and α2-adrenoceptor, and this effect of noradrenaline was blocked by local LSA pretreatment with the cocktail containing WB4101 and RX821002. The present results provide advances in our understanding of the baroreflex neural circuitry. Taken together, data suggest that local LSA α1- and α2-adrenoceptors differently modulate baroreflex control of heart rate. Data indicate that LSA α1-adrenoceptors exert a facilitatory modulation on baroreflex bradycardia, whereas local α2-adrenoceptors exert an inhibitory modulation on reflex tachycardia.
Authors:
America Augusto Scopinho; Fernando Hf Alves; Leonardo Bm Resstel; Fernando Ma Correa; Carlos C Crestani
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-12-16
Journal Detail:
Title:  Experimental physiology     Volume:  -     ISSN:  1469-445X     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1 School of Medicine of Ribeirao Preto, USP;
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