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Title: Neuropeptides in the posterodorsal medial amygdala modulate central cardiovascular reflex responses in awake male rats
Authors: Quagliotto, Edson
Casali, Karina Rabello [UNIFESP]
Dal Lago, Pedro
Rasia-Filho, Alberto Antonio
Univ Fed Ciencias Saude Porto Alegre
Univ Fed Rio Grande do Sul
Universidade Federal de São Paulo (UNIFESP)
Keywords: Baroreceptor and chemoreceptor reflexes
Power spectral analysis
Symbolic analysis
Angiotensin II
Issue Date: 1-Feb-2015
Publisher: Assoc Bras Divulg Cientifica
Citation: Brazilian Journal of Medical and Biological Research. São Paulo: Assoc Bras Divulg Cientifica, v. 48, n. 2, p. 128-139, 2015.
Abstract: The rat posterodorsal medial amygdala (MePD) links emotionally charged sensory stimuli to social behavior, and is part of the supramedullary control of the cardiovascular system. We studied the effects of microinjections of neuroactive peptides markedly found in the MePD, namely oxytocin (OT, 10 ng and 25 pg; n=6/group), somatostatin (SST, 1 and 0.05 mu M; n=8 and 5, respectively), and angiotensin II (Ang II, 50 pmol and 50 fmol; n=7/group), on basal cardiovascular activity and on baroreflex- and chemoreflex-mediated responses in awake adult male rats. Power spectral and symbolic analyses were applied to pulse interval and systolic arterial pressure series to identify centrally mediated sympathetic/parasympathetic components in the heart rate variability (HRV) and arterial pressure variability (APV). No microinjected substance affected basal parameters. On the other hand, compared with the control data (saline, 0.3 mu L; n=7), OT (10 ng) decreased mean AP (MAP(50)) after baroreflex stimulation and increased both the mean AP response after chemoreflex activation and the high-frequency component of the HRV. OT (25 pg) increased overall HRV but did not affect any parameter of the symbolic analysis. SST (1 mu M) decreased MAP(50), and SST (0.05 mu M) enhanced the sympathovagal cardiac index. Both doses of SST increased HRV and its low-frequency component. Ang II (50 pmol) increased HRV and reduced the two unlike variations pattern of the symbolic analysis (P<0.05 in all cases). These results demonstrate neuropeptidergic actions in the MePD for both the increase in the range of the cardiovascular reflex responses and the involvement of the central sympathetic and parasympathetic systems on HRV and APV.
ISSN: 0100-879X
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