Iron Deficiency Alters Iron Regulatory Protein and Iron Transport Protein Expression in the Perinatal Rat Brain

Iron plays an important role in numerous vital enzyme systems in the perinatal brain. The membrane proteins that mediate iron transport [transferrin receptor (TfR) and divalent metal transporter 1 (DMT-1)] and the iron regulatory proteins (IRP-1 and IRP-2) that stabilize their mRNAs undergo regional developmental changes in the iron-sufficient rat brain between postnatal day (P) 5 and 15. Perinatal iron deficiency (ID) affects developing brain regions nonhomogeneously, suggesting potential differences in regional iron transporter and regulatory protein expression. The objective of the study was to determine the effect of perinatal ID on regional expression of IRP-1, IRP-2, TfR, and DMT-1 in the developing rat brain. Gestationally iron-deficient Sprague Dawley rat pups were compared with iron-sufficient control pups at P10. Serial 12-mu coronal sections of fixed frozen brain from pups on P10 were assessed by light microscopy for IRP-1, IRP-2, DMT-1, and TfR localization. ID did not change the percentage of cells with positive staining for the four proteins in the choroid epithelium, ependyma, vascular endothelium, or neurons of the striatum. ID increased the percentage of neurons expressing the four proteins in the hippocampus and the cerebral cortex. Increased numbers of TfR- and DMT-1-positive cells were always associated with increased IRP-positive cells. The P10 rat responds to perinatal ID by selectively increasing the number of neurons expressing IRP-regulated transporters in brain regions that are rapidly developing, without any change at transport surfaces or in regions that are quiescent. Brain iron distribution during ID seems to be locally rather than globally regulated.