title: Neuropeptides in the posterodorsal medial amygdala modulate central cardiovascular reflex responses in awake male rats.
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.
authors.affiliation: Departamento de Ciências Básicas da Saúde/Fisiologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil.
authors.forename: E
authors.initials: E
authors.lastname: Quagliotto
authors.affiliation: Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, São José dos Campos, SP, Brasil.
authors.forename: K R
authors.initials: KR
authors.lastname: Casali
authors.affiliation: Departamento de Fisioterapia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil.
authors.forename: P
authors.initials: P
authors.lastname: Dal Lago
authors.affiliation: Departamento de Ciências Básicas da Saúde/Fisiologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil.
authors.forename: A A
authors.initials: AA
authors.lastname: Rasia-Filho
mesh_terms: D000704:Analysis of Variance; D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects*; D017704:Baroreflex / Q000187:drug effects*; D001921:Brain / Q000033:anatomy & histology; D002319:Cardiovascular System / Q000294:innervation; D066276:Corticomedial Nuclear Complex / Q000187:drug effects* / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D008845:Microinjections; D009479:Neuropeptides / Q000008:administration & dosage / Q000494:pharmacology*; D010121:Oxytocin / Q000008:administration & dosage; D010275:Parasympathetic Nervous System / Q000187:drug effects; D017208:Rats, Wistar; D013004:Somatostatin / Q000008:administration & dosage; D018709:Statistics, Nonparametric; D013564:Sympathetic Nervous System / Q000187:drug effects; D062666:Vascular Access Devices; D014851:Wakefulness
chemical_list: D009479:Neuropeptides; D000804:Angiotensin II; D010121:Oxytocin; D013004:Somatostatin