Background: Iron deficiency (ID) compromises the developing nervous system, including the hippocampus, resulting in later-life deficits despite iron repletion. The iron-dependent molecular changes driving these lasting deficits, and the effect of early iron repletion, are incompletely understood. Previous studies have utilized dietarymodels ofmaternal-fetal ID anemia (IDA) to address these questions; however, concurrent anemia prevents delineation of the specific role of iron. Objective: The aim of the study was to isolate the effects of developmental ID on adult hippocampal gene expression and to determine if iron repletion reverses these effects in a mouse model of nonanemic hippocampal neuronal ID. Methods: Nonanemic, hippocampus-specific neuronal ID was generated by using a Tet-OFF dominant negative transferrin receptor (DN-TFR1) mouse model that impairs cellular iron uptake. Hippocampal ID was reversed with doxycycline at postnatal day 21 (P21) in a subset of mice to create 2 experimental groups, chronically iron-deficient and formerly iron-deficient mice, which were compared with their respective doxycycline-treated and untreated ironsufficient controls. RNA from adult male hippocampi was sequenced. Paired-end reads were analyzed for differential expression. Differentially expressed genes were analyzed in Ingenuity Pathway Analysis. Results: A total of 346 genes were differentially expressed in adult, chronically iron-deficient hippocampi compared with controls. ID dysregulated genes in critical neurodevelopmental pathways, including axonal guidance, CDK5, Ephrin receptor, Rac, and Neurotrophin/Trk signaling. Iron repletion at P21 normalized adult hippocampal expression of 198 genes; however, genes involved in cAMP response element-binding protein (CREB) signaling, neurocognition, and neurologic disease remained dysregulated in adulthood. Conclusions: Chronic ID during development, independent of anemia, alters the adult mouse hippocampal transcriptome. Restoring iron status during a known critical period of hippocampal neurodevelopment incompletely normalized these changes, suggesting a need for additional studies to identify the most effective timeline for iron therapy, and adjunctive treatments that can fully restore ID-induced molecular changes, particularly in human populations in whom chronic ID is endemic.
Bibliographical noteFunding Information:
Supported by Eunice Kennedy Shriver National Institute of Child Health and Human Development grants R21-HD054490 and R01-HD029421 and the University of Minnesota Masonic Children’s Fund (to MKG). Author disclosures: AB, SJBF, MKG, and PVT, no conflicts of interest. Supplemental Data 1 and 2 are available from the “Supplementary data” link in the online posting of the article and from the same link in the online table of contents at https://academic.oup.com/jn/.
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- developmental origins of disease