title: Amygdalar neuronal activity mediates the cardiovascular responses evoked from the dorsolateral periaqueductal gray in conscious rats.
abstract: There is ample evidence that both lateral/dorsolateral periaqueductal gray (l/dlPAG) and basolateral amygdala (BLA) are essential for the regulation of the autonomic responses evoked during innate reactions to threatening stimuli. However, it is not well established to what extent the BLA regulates the upstream functional connection from the l/dlPAG. Here we evaluated the role of the BLA and its glutamatergic receptors in the cardiovascular responses induced by l/dlPAG stimulation in rats. We examined the influence of acute inhibition of the BLA, unilaterally, by injecting muscimol on the cardiovascular responses evoked by the injection of N-methyl D-aspartate (NMDA) into the l/dlPAG. We also evaluated the role of BLA ionotropic glutamate receptors in these responses by injecting antagonists of NMDA and AMPA/kainate receptor subtypes into the BLA. Our results show that the microinjection of NMDA in the BLA increased the mean arterial pressure (MAP) and heart rate (HR). Injection of NMDA into the l/dlPAG caused similar increases in these variables, which was prevented by the prior injection of muscimol, a GABAA agonist, into the BLA. Moreover, injection of glutamatergic antagonists (2-amino-5-phosphonopentanoate (AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)) into the BLA reduced the increase in MAP and HR induced by l/dlPAG activation. Finally, the inhibition of the central amygdala neurons failed to reduce the cardiovascular changes induced by l/dlPAG activation. These results indicate that physiological responses elicited by l/dlPAG activation require the neuronal activity in the BLA. This ascending excitatory pathway from the l/dlPAG to the BLA might ensure the expression of the autonomic component of the defense reaction.
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: arrabreu@gmail.com.
authors.forename: A R
authors.initials: AR
authors.lastname: de Abreu
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: alirriba@yahoo.com.br.
authors.forename: A R
authors.initials: AR
authors.lastname: Abreu
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: laugbatista@yahoo.com.br.
authors.forename: L T
authors.initials: LT
authors.lastname: Santos
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: alinearlindo.nut@gmail.com.
authors.forename: A A
authors.initials: AA
authors.lastname: de Souza
authors.affiliation: Department of Basic Health Sciences, Federal University of Juiz de Fora, Governador Valadares, MG, Brazil. Electronic address: luiz.gonzaga@ufjf.edu.br.
authors.forename: L G
authors.initials: LG
authors.lastname: da Silva
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: deochianca@gmail.com.
authors.forename: D A
authors.initials: DA
authors.lastname: Chianca
authors.affiliation: Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto (UFOP), Ouro Preto, MG 35400-000, Brazil. Electronic address: rodrigo.menezes@iceb.ufop.br.
authors.forename: R C
authors.initials: RC
authors.lastname: de Menezes
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*
chemical_list: D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D058785:GABA-A Receptor Agonists; D011963:Receptors, GABA-A; D017470:Receptors, Glutamate; D009118:Muscimol; D018698:Glutamic Acid; D016202:N-Methylaspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate
keywords: basolateral amygdala; defense reaction; glutamatergic receptors; periaqueductal gray