Impact of ovariectomy and CO2 inhalation on microglia morphology in select brainstem and hypothalamic areas regulating breathing in female rats

Autor(es)

Marques, Danuzia A. ^[1] ; Gargaglioni, Luciane H. ^[2] ; Joseph, Vincent ^[1] ; Bretzner, Frederic ^[3] ; Bicego, Kenia C. ^[2] ; Fournier, Stephanie ^[1] ; Kinkead, Richard ^[1]

Afiliação do(s) autor(es)

^[1] Univ Laval, Ctr Rech Inst Univ Cardiol & Pneumol Quebec, Dept Pediat, Quebec City, PQ - Canada

^[2] Sao Paulo State Univ, UNESP FCAV Jaboticabal, Dept Anim Morphol & Physiol, Jaboticabal, SP - Brazil

^[3] Univ Laval, Ctr Rech CHU Quebec, Dept Psychiat & Neurosci, Quebec City, PQ - Canada

• Tipo de documento: Artigo Científico
• Fonte: Brain Research; v. 1756, APR 1 2021.
• Citações Web of Science: 0

Resumo

The neural network that regulates breathing shows a significant sexual dimorphism. Ovarian hormones contribute to this distinction as, in rats, ovariectomy reduces the ventilatory response to CO2. Microglia are neuroimmune cells that are sensitive to neuroendocrine changes in their environment. When reacting to challenging conditions, these cells show changes in their morphology that reflect an augmented capacity for producing pro- and anti-inflammatory cytokines. Based on evidence suggesting that microglia contribute to sex-based differences in reflexive responses to hypercapnia, we hypothesized that ovariectomy and hypercapnia promote microglial reactivity in selected brain areas that regulate breathing. We used ionized calcium-bindingadapter molecule-1 (Iba1) immunolabeling to compare the density and morphology of microglia in the locus coeruleus (LC), the caudal medullary raphe, the caudal part of the nucleus of the tractus solitarius (cNTS), and the paraventricular nucleus of the hypothalamus (PVN). Tissue was obtained from SHAM (metaestrus) female rats or following ovariectomy. Rats were exposed to normocapnia or hypercapnia (5% CO2, 20 min). Ovariectomy and hypercapnia did not affect microglial density in any of the structures studied. Ovariectomy promoted a reactive phenotype in the cNTS and LC, as indicated by a larger morphological index. In these structures, hypercapnia had a relatively modest opposing effect; the medullary raphe or the PVN were not affected. We conclude that ovarian hormones attenuate microglial reactivity in CO2/H+ sensing structures. These data suggest that microglia may contribute to neurological diseases in which anomalies of respiratory control are associated with cyclic fluctuations of ovarian hormones or menopause. (AU)

• Processo FAPESP: 19/09469-8 - Efeito da temperatura de incubação no metabolismo, termorregulação e quimiossensibilidade de frangos
• Beneficiário: Luciane Helena Gargaglioni Batalhão
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/21730-5 - Localização dos receptores beta’ de progesterona na membrana de neurônios respiratórios do cérebro de ratos machos e fêmeas e efeitos da hipóxia
• Beneficiário: Danuzia Ambrozio Marques
• Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Doutorado