Immunoreactivity for neuronal NOS and fluorescent indication of NO formation in the NTS of juvenile rats submitted to chronic intermittent hypoxia

Autor(es)

Pajolla, Gisela P. ^[1] ; Accorsi-Mendonca, Daniela ^[1] ; Lunardi, Claure N. ^[2] ; Bendhack, Lusiane M. ^[2] ; Machado, Benedito H. ^[1] ; Llewellyn-Smith, Ida J. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Sch Pharmaceut Sci Ribeirao Preto, Dept Chem & Phys, BR-14049900 Ribeirao Preto, SP - Brazil

^[3] Flinders Univ S Australia, Cardiovasc Med & Ctr Neurosci, Bedford Pk, SA 5042 - Australia

• Tipo de documento: Artigo de Revisão
• Fonte: AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL; v. 148, n. 1-2, p. 55-62, JUN 15 2009.
• Citações Web of Science: 8

Resumo

Exposure to chronic intermittent hypoxia (CIH) leads to significant autonomic and respiratory changes, similar to those observed in obstructive sleep apnea. The hypertension associated with CIH is due to sympathoexcitation triggered by long-term exposure to intermittent hypoxia. However, the mechanisms underlying these effects are unknown. Changes in central regulation of sympathetic activity may underlie CIH-induced hypertension. Since NO appears to be mainly sympathoinhibitory in the nucleus of the solitary tract (NTS), we hypothesized that CIH augments sympathetic activity, in part by reducing neuronal nitric oxide synthase (nNOS) expression and consequently nitric oxide (NO) production in this brain region. To test our hypothesis, juvenile male Wistar rats were exposed to CIH for 8 h/day for 10 days and sections of perfused brainstem were either stained to reveal nNOS-immunoreactivity or loaded with OAF 2-DA to label neurons containing NO. CIH rats showed a significant increase in mean arterial pressure and heart rate compared to controls. However, there was no significant difference in the distribution, staining intensity or numbers of nNOS-immuno reactive neurons in the NTS between experimental and control rats. We also found no significant change in NO content in the DAF 2-DA-loaded sections of NTS from CIH rats. Our data show that NO is not altered in the NTS of juvenile CIH rats, suggesting that nitrergic mechanisms, at least in the NTS, are unlikely to be involved in the sympathetic excitation that generates the hypertension observed after 10 days of CIH. (C) 2009 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 04/08868-0 - Consolidação do Centro de Microscopia Funcional do Campus da USP/ Ribeirão Preto
• Beneficiário: Roy Edward Larson
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 04/03285-7 - Mecanismos centrais da excitação simpática promovida pela hipóxia
• Beneficiário: Benedito Honorio Machado
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 04/08712-0 - Imunorreatividade aos receptores de aminoacidos excitatorios e purinergicos no nucleo do trato solitario (nts) de ratos submetidos a hipoxia cronica intermitente.
• Beneficiário: Gisela Pugliesi Pajolla
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado