The medial amygdaloid nucleus is involved in the cardiovascular pathway activated by noradrenaline into the lateral septal area of rats

Abstract

We have previously reported that noradrenaline (NA) microinjected into the lateral septal area (LSA) caused pressor and bradicardic responses that were mediated by vasopressin release into the circulation through the paraventricular nucleus of hypothalamus (PVN). Although PVN is the final structure involved in the cardiovascular responses caused by NA in the LSA, there is no evidence of direct connections between these areas, suggesting that some structures could be links in this pathway. In the present study, we verified the effect of reversible synaptic inactivation of the medial amygdaloid nucleus (MeA), bed nucleus of stria terminalis (BNST) or diagonal band of Broca (DBB) with Cobalt Chloride (CoCl(2) ) on the cardiovascular response to NA microinjection into the LSA of unanesthetized rats. Male Wistar rats had guide cannulae implanted into the LSA and the MeA, BNST or DBB for drug administration, and a femoral catheter for blood pressure and heart rate recordings. Local microinjection of CoCl(2) (1 mm in 100 nL) into the MeA significantly reduced the pressor and bradycardic responses caused by NA microinjection (21 nmol in 200 nL) into the LSA. In contrast, microinjection of CoCl(2) into the BNST or DBB did not change the cardiovascular responses to NA into the LSA. The results indicate that synapses within the MeA, but not in BNST or DBB, are involved in the cardiovascular pathway activated by NA microinjection into the LSA.

Mechanisms in the Bed Nucleus of the Stria Terminalis Involved in Control of Autonomic and Neuroendocrine Functions: A Review

“…Considering that the LSA does not project directly to PVN [204], and connections have been described between the BST and this hypothalamic structure [14], the BST could be a relay in the pathway of vasopressin release by the LSA. However, although noradrenaline microinjection into the LSA activate local BNST neurons [205], functional findings demonstrated that BNST inhibition did not affect cardiovascular responses to noradrenaline into the LSA [206]. Since other forebrain structures connected with BNST, such as MPFC and MeA, also modulates cardiovascular function through control of vasopressin release [197, 207], further studies are necessary to clarify the neural circuitry that the BNST is part.…”

Amygdaloid involvement in the defensive behavior of mice exposed to the open elevated plus-maze

“…Cobalt chloride (CoCl 2 ; Sigma-Aldrich, Brazil) was dissolved in 0.9% physiological saline solution which alone served as control solution. The dose of 1.0 mM of CoCl 2 was based on previous studies [34,35], and the total volume of injection within the amygdala was 0.1 μL.…”

Função da neurotransmissão noradrenérgica do núcleo medial da amígdala na modulação do sistema cardiovascular em ratos

“…A estimulação dessa área pela microinjeção local de NA causa respostas pressora e bradicárdica (SCOPINHO et al, 2006) que também são mediadas pela liberação de vasopressina para a circulação sanguinea após ativação do NPV (SCOPINHO et al, 2008). A resposta pressora e bradicárdica causada pela NA na área septal lateral foi significativamente reduzida pela administração do inbidor sináptico CoCl 2 no NMA (SCOPINHO et al, 2012). Considerando que a área septal lateral não envia projeções diretamente ao NPV (TAVARES et al, 2005) e que foram descritas conexões entre NMA e essa estrutura (CANTERAS et al, 1995), esses resultados sugerem que NMA é um relé na via envolvida na liberação vasopressina após a ativação da área septal lateral após estimulação local com NA.…”