title: The medial amygdaloid nucleus modulates the baroreflex activity in conscious rats.
abstract: The medial amygdaloid nucleus (MeA) is involved in cardiovascular control. In the present study we report the effect of MeA pharmacological ablations caused by bilateral microinjections of the nonselective synaptic blocker CoCl2 on cardiac baroreflex responses in rats. MeA synaptic inhibition evoked by local bilateral microinjection of 100 nL of CoCl2 (1 mM) did not affect blood pressure or heart rate baseline, suggesting no tonic MeA influence on resting cardiovascular parameters. However, 10 min after CoCl2 microinjection into the MeA of male Wistar rats, the reflex bradycardic response evoked by intravenous infusion of phenylephrine was significantly enhanced when compared with the reflex bradycardic response observed before CoCl2. The treatment did not affect the tachycardic responses to the intravenous infusion of sodium nitroprusside (SNP). Baroreflex activity returned to control values 60 min after CoCl2 microinjections, confirming a reversible blockade. The present results indicate an involvement of the MeA in baroreflex modulation, suggesting that synapses in the MeA have an inhibitory influence on the bradycardic component of the baroreflex in conscious rats.
authors.affiliation: Departments of Pharmacology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14090-090, Brazil.
authors.forename: Eduardo Albino Trindade
authors.initials: EA
authors.lastname: Fortaleza
authors.affiliation: Departments of Pharmacology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14090-090, Brazil.
authors.forename: Nilson Carlos
authors.initials: NC
authors.lastname: Ferreira-Junior
authors.affiliation: Departments of Pharmacology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14090-090, Brazil.
authors.forename: Davi Campos
authors.initials: DC
authors.lastname: Lagatta
authors.affiliation: Departments of Pharmacology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14090-090, Brazil.
authors.forename: Leonardo Barbosa Moraes
authors.initials: LB
authors.lastname: Resstel
authors.affiliation: Departments of Pharmacology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14090-090, Brazil. Electronic address: fmdacorr@fmrp.usp.br.
authors.forename: Fernando Morgan Aguiar
authors.initials: FM
authors.lastname: Corrêa
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001919:Bradycardia / Q000503:physiopathology; D002491:Central Nervous System Agents / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D003243:Consciousness / Q000502:physiology; D066276:Corticomedial Nuclear Complex / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D017208:Rats, Wistar; D013610:Tachycardia / Q000503:physiopathology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D002491:Central Nervous System Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D003035:Cobalt; C018021:cobaltous chloride
keywords: Baroreflex; Cardiovascular system; CoCl(2); Medial amygdaloid nucleus