Alterations in glucose concentrations affect DNA methylation at Lrg1 in an exvivo rat cortical slice model of preterm brain injury

Preterm birth affects 5-18% of all babies and is associated with neurodevelopmental impairment and increased neuropsychiatric disease risk. Although preterm birth associates with differential DNA methylation at neurodevelopmental genes in buccal DNA, including leucine-rich alpha-2-glycoprotein 1 (LRG1), it is not known whether these differences also occur in the brain, or whether they persist. Thus, there is a need for animal models or invitro systems in which to undertake longitudinal and mechanistic studies. We used a combination of invivo rat studies and exvivo experiments in rat cortical slices to explore their utility in modelling the human preterm brain. We identified temporal changes in DNA methylation at LRG1 in human buccal DNA over the first year of life and found persistent differences in LRG1 methylation between preterm and term infants at 1year. These developmental changes also occurred in rat brains invivo, alongside changes in global DNA hydroxymethylation and expression of the ten-eleven translocation (Tet1) enzyme, and were reproducible in exvivo rat cortical slices. On the basis of the observation that neonatal glucose homeostasis can modify neurodevelopmental outcome, we studied whether glucose concentration affects Lrg1 methylation using cortical slices. Culture of slices in lower glucose concentration was associated with lower Lrg1 methylation, lower global 5hmC and Tet1 expression. Our results suggest that exvivo organotypic cultures may be useful in the study of biological and environmental influences on the epigenome and that perturbations during early life including glucose concentration can affect methylation at specific genes implicated in neurodevelopment.