Abstract
Background
Pregnant women at a high risk of preterm delivery receive glucocorticoids to accelerate fetal lung maturation and surfactant synthesis. However, the effect of antenatal steroids on the developing diaphragm remains unclear. We hypothesized that maternal betamethasone impairs the fetal diaphragm, and the magnitude of the detrimental effect increases with longer duration of exposure. We aimed to determine how different durations of fetal exposure to maternal betamethasone treatment influence the fetal diaphragm at the functional and molecular levels.
Methods
Date-mated merino ewes received intramuscular injections of saline (control) or two doses of betamethasone (5.7 mg) at an interval of 24 h commencing either 2 or 14 days before delivery. Preterm lambs were killed after cesarean delivery at 121-day gestational age. In vitro contractile measurements were performed on the right hemidiaphragm, whereas molecular/cellular analyses used the left costal diaphragm.
Results
Different durations of fetal exposure to maternal betamethasone had no consistent effect on the protein metabolic pathway, expression of glucocorticoid receptor and its target genes, cellular oxidative status, or contractile properties of the fetal lamb diaphragm.
Conclusion
These data suggest that the potential benefits of betamethasone exposure on preterm respiratory function are not compromised by impaired diaphragm function after low-dose maternal intramuscular glucocorticoid exposure.
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Acknowledgements
The study was supported by a National Health and Medical Research Council (NHMRC) Centre for Research Excellence (1057514), NHMRC Project Grant (1010665), NHMRC Senior Research Fellowship (1077691) and Career Development Fellowship (1045824) and the Women and Infants Research Foundation.
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Mahzabin, T., Pillow, J., Pinniger, G. et al. Influence of antenatal glucocorticoid on preterm lamb diaphragm. Pediatr Res 82, 509–517 (2017). https://doi.org/10.1038/pr.2017.99
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DOI: https://doi.org/10.1038/pr.2017.99
