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Effect of maternal steroid on developing diaphragm integrity

Citation

Song, Y and Demmer, DL and Pinniger, GJ and Lavin, T and MacMillan, MV and Pillow, JJ and Bakker, AJ, Effect of maternal steroid on developing diaphragm integrity, PLoS One, 9, (3) Article e93224. ISSN 1932-6203 (2014) [Refereed Article]


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Copyright Statement

Copyright 2014 Song et al. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1371/journal.pone.0093224

Abstract

Antenatal steroids reduce the severity of initial respiratory distress of premature newborn babies but may have an adverse impact on other body organs. The study aimed to examine the effect of maternal steroids on postnatal respiratory muscle function during development and elucidate the mechanisms underlying the potential myopathy in newborn rats. Pregnant rats were treated with intramuscular injections of 0.5 mg/kg betamethasone 7 d and 3 d before birth. Newborn diaphragms were dissected for assessment of contractile function at 2 d, 7 d or 21 d postnatal age (PNA), compared with age-matched controls. The expression of myosin heavy chain (MHC) isoforms and atrophy-related genes and activity of intracellular molecular signalling were measured using quantitative PCR and/or Western blot. With advancing PNA, neonatal MHC gene expression decreased progressively while MHC IIb and IIx isoforms increased. Protein metabolic signalling showed high baseline activity at 2 d PNA, and significantly declined at 7 d and 21 d. Antenatal administration of betamethasone significantly decreased diaphragm force production, fatigue resistance, total fast fibre content and anabolic signalling activity (Akt and 4E-BP1) in 21 d diaphragm. These responses were not observed in 2 d or 7 d postnatal diaphragm. Results demonstrate that maternal betamethasone treatment causes postnatal diaphragmatic dysfunction at 21 d PNA, which is attributed to MHC II protein loss and impairment of the anabolic signalling pathway. Developmental modifications in MHC fibre composition and protein signalling account for the age-specific diaphragm dysfunction.

Item Details

Item Type:Refereed Article
Keywords:steroid, diaphragm dysfunction, newborn
Research Division:Medical and Health Sciences
Research Group:Cardiorespiratory Medicine and Haematology
Research Field:Respiratory Diseases
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Respiratory System and Diseases (incl. Asthma)
UTAS Author:Song, Y (Dr Yong Song)
ID Code:135705
Year Published:2014
Web of Science® Times Cited:6
Deposited By:Menzies Institute for Medical Research
Deposited On:2019-11-08
Last Modified:2019-12-09
Downloads:3 View Download Statistics

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