New insights on amygdala: Basomedial amygdala regulates the physiological response to social novelty.
The amygdala has been associated with a variety of functions linked to physiological, behavioral and endocrine responses during emotional situations. This brain region is comprised of multiple sub-nuclei. These sub-nuclei belong to the same structure, but may be involved in different functions, thereby making the study of each sub-nuclei important. Yet, the involvement of the basomedial amygdala (BMA) in the regulation of emotional states has yet to be defined. Therefore, the aim of our study was to investigate the regulatory role of the BMA on the responses evoked during a social novelty model and whether the regulatory role depended on an interaction with the dorsomedial hypothalamus (DMH). Our results showed that the chemical inhibition of the BMA by the microinjection of muscimol (γ-aminobutyric acid (GABAA) agonist) promoted increases in mean arterial pressure (MAP) and heart rate (HR), whereas the chemical inhibition of regions near the BMA did not induce such cardiovascular changes. In contrast, the BMA chemical activation by the bilateral microinjection of bicuculline methiodide (BMI; GABAA antagonist), blocked the increases in MAP and HR observed when an intruder rat was suddenly introduced into the cage of a resident rat, and confined to the small cage for 15min. Additionally, the increase in HR and MAP induced by BMA inhibition were eliminated by DMH chemical inhibition. Thus, our data reveal that the BMA is under continuous GABAergic influence, and that its hyperactivation can reduce the physiological response induced by a social novelty condition, possibly by inhibiting DMH neurons.
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: laugbatista@yahoo.com.br.
Laura Tavares
LT
Mesquita
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: alirriba@yahoo.com.br.
Aline Rezende
AR
Abreu
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: arrabreu@gmail.com.
Alessandra Rezende
AR
de Abreu
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: alinearlindo.nut@gmail.com.
Aline Arlindo
AA
de Souza
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: sylvana.nut@gmail.com.
Sylvana Rendeiro
SR
de Noronha
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: fernandasilva_nut@yahoo.com.br.
Fernanda Cacilda
FC
Silva
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: glendasiqueira@hotmail.com.
Glenda Siqueira Viggiano
GS
Campos
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: deochianca@gmail.com.
Deoclecio Alves
DA
Chianca
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil. Electronic address: rodrigo.menezes@iceb.ufop.br.
Rodrigo Cunha
RC
de Menezes
D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001640:Bicuculline / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*; D012938:Social Perception; D013315:Stress, Psychological / Q000188:drug therapy / Q000378:metabolism
D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D009118:Muscimol; C017069:bicuculline methiodide; D001640:Bicuculline
dorsomedial hypothalamus; intruder rat; social novelty basomedial amygdala