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Effect of premature delivery on rat lung retinol (vitamin A) and retinyl ester stores
1University of Wisconsin Perinatal Center, Meriter Hospital, Madison General, Madison, Wisc.
Insights
Fetal lung stores of retinyl palmitate (a form of vitamin A) decrease significantly after preterm birth, whether delivered vaginally or by C-section. This mobilization suggests a readily available source of vitamin A upon delivery.
Area of Science:
- Neonatal physiology
- Nutritional biochemistry
- Respiratory medicine
Background:
- Low plasma retinol (vitamin A) is linked to bronchopulmonary dysplasia in premature infants.
- Vitamin A deficiency causes respiratory tract lesions similar to bronchopulmonary dysplasia.
- Fetal rat lung retinyl palmitate stores decrease significantly around term/postpartum.
Purpose of the Study:
- To investigate the mobilization of fetal lung retinyl palmitate stores after preterm delivery.
- To compare lung retinol and retinyl palmitate levels in fetuses delivered preterm via C-section versus those remaining in utero.
Main Methods:
- Comparison of lung retinol and retinyl palmitate concentrations.
- Analysis of 21-day gestation rat fetuses delivered by cesarean section and allowed to breathe for 4 hours.
- Comparison with in utero littermate controls.
Main Results:
- Lungs of fetuses delivered preterm and breathing for 4 hours showed significantly lower retinol (1.6 µg/g) and retinyl palmitate (11.3 µg/g) compared to in utero controls (2.2 µg/g retinol, 14.9 µg/g retinyl palmitate).
- These findings indicate a rapid decrease in lung retinyl palmitate post-delivery.
Conclusions:
- Fetal lung retinyl palmitate stores are readily mobilized upon delivery, both at term and preterm.
- This mobilization may represent a critical mechanism for providing vitamin A to the neonate after birth.
Abstract:
Low plasma retinol (vitamin A) in premature infants has been associated with bronchopulmonary dysplasia. Also, retinol (vitamin A) deficiency is characterized by loss of cilia and squamous metaplasia of the respiratory tract, similar to the histological lesions of bronchopulmonary dysplasia of the premature infant. Recent work showed that the fetal rat lung retinyl palmitate stores were high preterm, but fell abruptly between 21 days of gestation and postpartum. This report extends this observation by showing that lung retinyl palmitate also decreases after cesarean section delivery preterm. Lung retinol and retinyl palmitate in the lungs of 21-day gestation fetuses delivered by cesarean section and stimulated to breath were compared to their in utero littermates. In utero lungs contained 2.2 +/- 0.14 micrograms/g dry weight retinol and 14.9 +/- 0.8 micrograms/g dry weight retinyl palmitate. Lungs from littermates that had been removed from the uterus and breathed on their own for 4 h had lower retinol (1.6 +/- 0.08 micrograms/g) and retinyl palmitate (11.3 +/- 0.4 micrograms/g; p less than 0.01). Fetal lung contains retinyl palmitate stores that are readily mobilized with delivery at term or preterm.