title: Influence of antenatal glucocorticoid on preterm lamb diaphragm.
abstract: BackgroundPregnant 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.MethodsDate-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.ResultsDifferent 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.ConclusionThese 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.
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.|Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Tanzila
authors.initials: T
authors.lastname: Mahzabin
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.|Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: J Jane
authors.initials: JJ
authors.lastname: Pillow
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Gavin J
authors.initials: GJ
authors.lastname: Pinniger
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Bakker
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.|Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Noble
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Robert B
authors.initials: RB
authors.lastname: White
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.|Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Perth, Western Australia, Australia.|School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia.
authors.forename: Kanakeswary
authors.initials: K
authors.lastname: Karisnan
authors.affiliation: School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.|Centre for Neonatal Research and Education, Division of Paediatrics and Child Health, Medical School, The University of Western Australia, Perth, Western Australia, Australia.|School of Public Health, Curtin University, Perth, Western Australia, Australia.|Centre for Genetic Origins of Health and Disease, The University of Western Australia and Curtin University, Perth, Western Australia, Australia.
authors.forename: Yong
authors.initials: Y
authors.lastname: Song
mesh_terms: D000818:Animals; D001623:Betamethasone / Q000008:administration & dosage*; D015153:Blotting, Western; D002585:Cesarean Section; D003964:Diaphragm / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation; D005865:Gestational Age; D005938:Glucocorticoids / Q000008:administration & dosage*; D008285:Major Histocompatibility Complex / Q000235:genetics; D018811:Maternal Exposure; D009119:Muscle Contraction / Q000187:drug effects; D059748:Proteolysis; D012313:RNA / Q000302:isolation & purification; D011965:Receptors, Glucocorticoid / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012756:Sheep / Q000196:embryology*; D015398:Signal Transduction
chemical_list: D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; D012313:RNA; D001623:Betamethasone