Neuropeptides in the posterodorsal medial amygdala modulate central cardiovascular reflex responses in awake male rats
Braz. j. med. biol. res
;
48(2): 128-139, 02/2015. tab, graf
Article
in English
| LILACS
| ID: lil-735856
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 μM; 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 µL; n=7), OT (10 ng) decreased mean AP (MAP50) 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 μM) decreased MAP50, and SST (0.05 μM) 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.
Full text:
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Index:
LILACS (Americas)
Main subject:
Wakefulness
/
Neuropeptides
/
Baroreflex
/
Arterial Pressure
/
Corticomedial Nuclear Complex
/
Heart Rate
Type of study:
Prognostic study
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2015
Type:
Article
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal de Ciências da Saúde de Porto Alegre/BR
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