Effect of Maternal Protein Restriction on the Surfactant System during Early Postnatal Life

Abstract

IntroductionIntra‐uterine growth restriction (IUGR) is defined by a low birth weight and contributes to a variety of adult‐onset diseases with different severities between males and females. There is some evidence for structural and functional changes to the lung during the post‐natal period. However, the specific changes over time and the effects of IUGR on the pulmonary surfactant system are not fully elucidated. Pulmonary surfactant is critical for normal respiration, it is a lipid‐protein mixture which coats the inside of the lung and maintains the lungs' ability to expand easily during respiration. Therefore, in this study we investigated the effects of IUGR on the surfactant system and lung function during early postnatal life. It was hypothesized that IUGR leads to lung dysfunction through alterations of the pulmonary surfactant system.Materials and MethodsIUGR was induced in a pregnant rat model via a low protein diet. Briefly, pregnant rats were randomized to a control 20% or a low 8% protein diet. Rats at days 1, 7 and 21 were euthanized, and were either lavaged immediately (day 1) or were analyzed for lung compliance and elastance using a FlexiVent followed by lung lavage (day 7 and 21). Lavage was processed to obtain surfactant which was analyzed via phospholipid‐phosphorus measurements.ResultsWeights were significantly lower in IUGR offspring in all age groups compared to control offspring. Surfactant analysis demonstrated a significant decrease in the amount of phospholipid surfactant of IUGR female offspring compared to control female offspring at day 1 (p<0.01). Also, the surfactant phospholipid content at birth (day 1) for both control and IUGR males and females was significantly higher compared to animals at day 7 and 21 (p<0.01). The results showed that lung compliance in 21‐day female IUGRs (but not male IUGRs) was significantly lower compared to female controls (p<0.01), while elastance was significantly higher for this group compare to female controls (p<0.01). Day 7 male and female offspring showed no difference for compliance and elastance compare to the control groups.Discussion and ConclusionIUGR resulted in alterations in surfactant content at day 1 and lung compliance at day 21 in IUGR females compared to control females. This shows that IUGR alters the lung function, and the effect was different between males and females. No changes in the extracellular surfactant content in 21‐day female IUGRs suggests that the lower lung compliance is potentially the result of alterations happened to surfactant biophysical properties under IUGR. These potential alterations will be investigated by assessing the reducing surface tension ability of the surfactant.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.