Acute hypoxia mediates expression of neuroglobin in the neonatal mouse brain Abbreviated title: Neuroglobin expression in neonatal mouse brain

Among endogenous adaptive systems to hypoxia, neuroglobin, a recently discovered heme protein, was suggested as a novel oxygen-dependent neuroprotectant. We aimed to characterize i) maturational age-related regulation of neuroglobin in the developing mouse brain under normoxic and hypoxic conditions, and ii) the role of hypoxia-inducible transcription factors (HIFs) as possible mediators of O(2)-dependent regulation of neuroglobin in vitro and in vivo. During early stages of postnatal brain maturation (P0-P14) neuroglobin mRNA levels significantly increased in developing mouse forebrains. By immunohistochemical analysis we confirmed expression of neuroglobin protein in the cytoplasm of developing neurons but not glial cells under normoxic conditions. Exposure of the immature brains (P0, P7) to acute (8% O(2), 6h) and chronic systemic hypoxia (10% O(2), 7days) led to differential activation of neuroglobin varying with maturational stage (P0, P7) and severity of hypoxia. This observation may indicate that neuroglobin is involved in adaptive responses of immature neurons to acute hypoxia during an early stage of mouse brain maturation (P0). In response to activation of the HIF system by prolyl-4-hydroxylase inhibitor (FG-4497), neuroglobin mRNA expression was significantly up-regulated in primary mouse cortical neurons (DIV6) exposed to normoxia and hypoxia (1% O(2)) compared to nontreated controls. In conclusion, present results strongly indicate that cerebral regulation of neuroglobin is related to maturational stage and that hypoxia-induced neuroglobin up-regulation is modified by the HIF system. DOI: https://doi.org/10.1016/j.expneurol.2012.04.006 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-62134 Accepted Version Originally published at: Hümmler, Nicolas; Schneider, Christina; Giessl, Andreas; Bauer, Reinhard; Walkinshaw, Gail; Gassmann, Max; Rascher, Wolfgang; Trollmann, Regina (2012). Acute hypoxia modifies regulation of neuroglobin in the neonatal mouse brain. Experimental Neurology, 236(1):112-121. DOI: https://doi.org/10.1016/j.expneurol.2012.04.006 Acute hypoxia mediates expression of neuroglobin in the neonatal mouse brain Abbreviated title: Neuroglobin expression in neonatal mouse brain Nicolas Hümmler, Christina Schneider, Andreas Giessl, Reinhard Bauer, Gail Walkinshaw, Max Gassmann, Wolfgang Rascher, Regina Trollmann Department of Pediatrics and Institute of Animal Physiology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany Institute of Physiology, University of Jena, Germany FibroGen Inc., San Francisco, California Institute of Veterinary Physiology, Vetsuisse Faculty, and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland Corresponding author: Regina Trollmann, MD Department of Pediatrics, Friedrich-Alexander-University of Erlangen-Nuremberg Loschgestrasse 15, 91054 Erlangen, Germany Tel: ++49/9131/853-3118; Fax: ++49/9131/853-3113 E-mail: [email protected] Number of pages (including figures/tables): 27 Number of figures: 7; Number of tables: 2 Number of words for Abstract: 207 Number of words for Introduction: 745 Number of words for Discussion: 1315 Acknowledgements: This work was supported by a scientific grant of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG, to R.T.). The authors are grateful to Gudrun Krischke (Department of Pediatrics, University of Erlangen, Germany) and Stephan Keller (Institute of Veterinary Physiology, University of Zürich, Switzerland) for their skilled technical assistance and support on the animal experiments, and to Michael Brodhun (Institute of Physiology, University of Jena) for support on TUNEL staining.