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 inhibiti...

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Bibliographic Details
Published in:Autonomic neuroscience 2015-12, Vol.193, p.44-50
Main Authors: Fortaleza, Eduardo Albino Trindade, Ferreira-Junior, Nilson Carlos, Lagatta, Davi Campos, Resstel, Leonardo Barbosa Moraes, Corrêa, Fernando Morgan Aguiar
Format: Article
Language:English
Subjects:
Advanced Basic Science
Animals
Baroreflex
Baroreflex - drug effects
Baroreflex - physiology
Bradycardia - physiopathology
Cardiovascular system
Central Nervous System Agents - pharmacology
Cobalt - pharmacology
CoCl2
Consciousness - physiology
Corticomedial Nuclear Complex - drug effects
Corticomedial Nuclear Complex - physiology
Male
Medial amygdaloid nucleus
Medical Education
Nitroprusside - pharmacology
Rats, Wistar
Tachycardia - physiopathology
Vasodilator Agents - pharmacology
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Summary: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.
ISSN:1566-0702
1872-7484
DOI:10.1016/j.autneu.2015.07.003