81: Maternal glucose supplementation alleviates intrauterine inflammation-induced inhibition of autophagy in fetal brain

Abstract

We have previously shown that fetal brain ceramide, a major component of myelin and an important inducer of autophagy, was decreased in the chorioamnionitis mouse model. Maternal glucose treatment increased ceramide levels and alleviated fetal brain injury. The objectives of this study were to determine whether autophagy is altered by lipopolysaccharide (LPS) - induced intrauterine (IU) inflammation and how maternal glucose supplementation ameliorates fetal brain injury. A mouse model of chorioamnionitis at term was utilized (n=36). Dams were randomly assigned to 4 groups: saline+saline, saline+glucose, LPS+saline and LPS+glucose. Pregnant CD-1 mice at E18 received either saline or LPS via IU injection. After surgery, dams received either 10% glucose (0.2ml at 2, 3, 4 and 5 h) or same amount of saline intraperitoneally. Fetal brains were collected at 6 h after LPS injection. Immunohistochemistry, western blot, electron microscopy (EM) and free fatty acid assay were performed on fetal brains. LPS injection significantly decreased autophagic markers, LC3 and beclin-1 protein levels in fetal brain compared to control by western blot; glucose treatment increased LC3 and beclin-1 expression following LPS exposure (p<0.05, One-way ANOVA). These results were confirmed by immunohistochemistry. EM demonstrated that immature autophagosome (incomplete closure of double membrane) appeared in LPS+saline group, accompanied by damaged cell morphology (endoplasmic reticulum stress). Glucose treatment decreased the immature autophagosome and improved cellular morphology. Free fatty acid analysis did not demonstrate changes between groups, indicating direct influence of glucose on ceramide levels. Maternal glucose administration after LPS-induced IU inflammation ameliorates a decrease in autophagy in fetal brain, suggesting a neuroprotective mechanism by which glucose prevents derangements of cellular metabolism. Clinically, these data suggest that once chorioamnionitis is diagnosed, maternal glucose supplementation may be of benefit in optimizing neurological outcomes in the offspring.