Abstract
Background: Antenatal corticosteroids (ACS) improve preterm neonatal outcomes. However, uncertainty remains regarding the safety of ACS exposure for the developing fetus, particularly its neurosensory development. Objectives: We investigated the effect of single and multiple ACS exposures on auditory nerve development in an ovine model of pregnancy. Methods: Ewes with a single fetus (gestational age [GA] 100 days) received an intramuscular injection of 150 mg medroxyprogesterone-acetate, followed by intramuscular (i) betamethasone (0.5 mg/kg) on days 104, 111, and 118 GA; (ii) betamethasone on day 104 and saline on days 111 and 118 GA; or (iii) saline on days 104, 111, and 118 GA, with de-livery on day 125 GA. Transmission electron microscope images of lamb auditory nerve preparations were digitally analyzed to determine auditory nerve morphology and myelination. Results: Relative to the control, mean auditory nerve myelin area was significantly increased in the multiple-treatment group (p < 0.001), but not in the single-treatment group. Increased myelin thickness was significantly changed only in a subgroup analysis for those axons with myelin thickness greater than the median value (p < 0.001). Morphological assessments showed that the increased myelin area was due to an increased likelihood of decompacted areas (p = 0.005; OR = 2.14, 95% CI 1.26-3.63; 31.6 vs. 18.2% in controls) and irregular myelin deposition (p = 0.001; OR = 5.91, 95% CI 2.16-16.19; 49.0 vs. 16.8% in controls) in the myelin sheath. Conclusions: In preterm sheep, ACS exposure increased auditory nerve myelin area, potentially due to disruption of normal myelin deposition. (c) 2018 S. Karger AG, Basel
Original language | English |
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Pages (from-to) | 62-68 |
Number of pages | 7 |
Journal | Neonatology |
Volume | 114 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Jan 2018 |
Keywords
- Antenatal corticosteroids
- Preterm lamb
- Neurosensory development
- Auditory nerve
- Myelination
- MULTIPLE COURSES
- FETAL SHEEP
- GLUCOCORTICOID TREATMENT
- CONTROLLED-TRIAL
- LUNG MATURATION
- AGE MACS-5
- BIRTH
- OUTCOMES
- BETAMETHASONE
- STEROIDS