Expression of genes related to the hypothalamic-pituitary-adrenal axis in murine fetal lungs in late gestationReport as inadecuate




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Reproductive Biology and Endocrinology

, 8:134

First Online: 04 November 2010Received: 06 July 2010Accepted: 04 November 2010

Abstract

BackgroundLung maturation is modulated by several factors, including glucocorticoids. Expression of hypothalamic-pituitary-adrenal HPA axis-related components, with proposed or described local regulatory systems analogous to the HPA axis, was reported in peripheral tissues. Here, HPA axis-related genes were studied in the mouse developing lung during a period overlapping the surge of surfactant production.

MethodsExpression of genes encoding for corticotropin-releasing hormone CRH, CRH receptors CRHR 1 and 2beta, CRH-binding protein, proopiomelanocortin POMC, melanocortin receptor 2 MC2R, and glucocorticoid receptor was quantified by real-time PCR and localized by in situ hydridization in fetal lungs at gestational days GD 15.5, 16.5, and 17.5, and was also quantified in primary mesenchymal- and epithelial cell-enriched cultures. In addition, the capability of CRH and adrenocorticotropic hormone ACTH to stimulate pulmonary expression of enzymes involved in the adrenal pathway of glucocorticoid synthesis was addressed, as well as the glucocorticoid production by fetal lung explants.

ResultsWe report that all the studied genes are expressed in fetal lungs according to different patterns. On GD 15.5, Mc2r showed peaks in expression in samples that have previously presented high mRNA levels for glucocorticoid synthesizing enzymes, including 11beta-hydroxylase Cyp11b1. Crhr1 mRNA co-localized with Pomc mRNA in cells surrounding the proximal epithelium on GD 15.5 and 16.5. A transition in expression sites toward distal epithelial cells was observed between GD 15.5 and 17.5 for all the studied genes. CRH or ACTH stimulation of genes involved in the adrenal pathway of glucocorticoid synthesis was not observed in lung explants on GD 15.5, whereas CRH significantly increased expression of 21-hydroxylase Cyp21a1 on GD 17.5. A deoxycorticosterone production by fetal lung explants was observed.

ConclusionsTemporal and spatial modulations of expression of HPA axis-related genes in late gestation are consistent with roles for these genes in lung development. Our data are likely to lead to valuable insights in relation to lung diseases originating from lung immaturity.

Electronic supplementary materialThe online version of this article doi:10.1186-1477-7827-8-134 contains supplementary material, which is available to authorized users.

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Author: Marc Simard - Mélissa Côté - Pierre R Provost - Yves Tremblay

Source: https://link.springer.com/



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