Lateral septal area alpha(1)-and alpha(2)-adrenoceptors differently modulate baroreflex activity in unanaesthetized rats

Autor(es)

Scopinho, America A. ^[1] ; Alves, Fernando H. F. ^[1] ; Resstel, Leonardo B. M. ^[1] ; Correa, Fernando M. A. ^[1] ; Crestani, Carlos C. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Pharmacol, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Sao Paulo State Univ, UNESP, Sch Pharmaceut Sci, Dept Nat Act Principles & Toxicol, BR-14801902 Araraquara, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Experimental Physiology; v. 97, n. 9, p. 1018-1029, SEP 2012.
• Citações Web of Science: 4

Resumo

The lateral septal area (LSA) is a limbic structure involved in autonomic, neuroendocrine and behavioural 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 unanaesthetized rats. Bilateral microinjection of the selective a1-adrenoceptor antagonist WB4101 (10 nmol in a volume of 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 a2-adrenoceptor antagonist RX821002 (10 nmol in 100 nl) increased baroreflex tachycardia without affecting reflex bradycardia. Treatment of the LSA with a cocktail containing WB4101 and RX821002 decreased baroreflex bradycardia and increased reflex tachycardia. The non-selective beta-adrenoceptor antagonist propranolol (10 nmol in 100 nl) did not affect either reflex bradycardia or tachycardia. Microinjection of noradrenaline into the LSA increased reflex bradycardia and decreased the baroreflex tachycardic response, an opposite effect compared with those observed after double blockade of a1- and a2-adrenoceptors, 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 a1- and a2-adrenoceptors modulate baroreflex control of heart rate differently. Data indicate that LSA a1-adrenoceptors exert a facilitatory modulation on baroreflex bradycardia, whereas local a2-adrenoceptors exert an inhibitory modulation on reflex tachycardia. (AU)

• Processo FAPESP: 09/03187-9 - Estudo do envolvimento do córtex pré-frontal medial de ratos nas respostas comportamentais observadas no modelo do lamber punido de Vogel: uma possível via receptores NMDA/ óxido nítrico e endocanabinoides
• Beneficiário: Leonardo Resstel Barbosa Moraes
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/16192-8 - Efeitos cardiovasculares decorrentes da administração crônica de testosterona e cocaína em ratos
• Beneficiário: Carlos Cesar Crestani
• Linha de fomento: Auxílio à Pesquisa - Regular