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Preserved placental oxygenation and development during severe systemic hypoxia


Schäffer, Leonhard; Vogel, Johannes; Breymann, Christian; Gassmann, Max; Marti, Hugo H (2006). Preserved placental oxygenation and development during severe systemic hypoxia. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 290(3):R844-R851.

Abstract

Local tissue oxygenation profoundly influences placental development. To elucidate the impact of hypoxia on cellular and molecular adaptation in vivo, pregnant mice at embryonic days 7.5-11.5 were exposed to reduced environmental oxygen (6-7% O2) for various periods of time. Hypoxia-inducible factor (HIF)-1alpha mRNA was highly expressed in the placenta, whereas HIF-2alpha was predominantly found in the decidua, indicating that HIF-1 is a relevant oxygen-dependent factor involved in placental development. During severe hypoxia, HIF-1alpha protein was strongly induced in the periphery but, however, not in the labyrinth layer of the placenta. Accordingly, no indication for tissue hypoxia in this central area was detected with 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide staining and VEGF expression as hypoxic markers. The absence of significant tissue hypoxia was reflected by preserved placental architecture and trophoblast differentiation. In the search for mechanisms preventing local hypoxia, we found upregulation of endothelial nitric oxide synthase (NOS) expression in the labyrinth layer. Inhibition of NOS activity by N(omega)-nitro-L-arginine methyl ester application resulted in ubiquitous placental tissue hypoxia. Our results show that placental oxygenation is preserved even during severe systemic hypoxia and imply that NOS-mediated mechanisms are involved to protect the placenta from maternal hypoxia.

Local tissue oxygenation profoundly influences placental development. To elucidate the impact of hypoxia on cellular and molecular adaptation in vivo, pregnant mice at embryonic days 7.5-11.5 were exposed to reduced environmental oxygen (6-7% O2) for various periods of time. Hypoxia-inducible factor (HIF)-1alpha mRNA was highly expressed in the placenta, whereas HIF-2alpha was predominantly found in the decidua, indicating that HIF-1 is a relevant oxygen-dependent factor involved in placental development. During severe hypoxia, HIF-1alpha protein was strongly induced in the periphery but, however, not in the labyrinth layer of the placenta. Accordingly, no indication for tissue hypoxia in this central area was detected with 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide staining and VEGF expression as hypoxic markers. The absence of significant tissue hypoxia was reflected by preserved placental architecture and trophoblast differentiation. In the search for mechanisms preventing local hypoxia, we found upregulation of endothelial nitric oxide synthase (NOS) expression in the labyrinth layer. Inhibition of NOS activity by N(omega)-nitro-L-arginine methyl ester application resulted in ubiquitous placental tissue hypoxia. Our results show that placental oxygenation is preserved even during severe systemic hypoxia and imply that NOS-mediated mechanisms are involved to protect the placenta from maternal hypoxia.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Obstetrics
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology

04 Faculty of Medicine > Center for Integrative Human Physiology
05 Vetsuisse Faculty > Institute of Veterinary Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:March 2006
Deposited On:15 Apr 2015 13:22
Last Modified:05 Apr 2016 19:13
Publisher:American Physiological Society
ISSN:0363-6119
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1152/ajpregu.00237.2005
PubMed ID:16195499
Permanent URL: https://doi.org/10.5167/uzh-110325

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