Neonatal mouse hippocampus: Phlebotomy-induced anemia diminishes and treatment with erythropoietin partially rescues mammalian target of rapamycin (mTOR) signaling

BACKGROUND: Phlebotomy-induced anemia (PIA) is common in premature infants and affects neurodevelopment. PIA alters hippocampal metabolism in neonatal mice through tissue hypoxia and iron deficiency. The mammalian target of rapamycin (mTOR) pathway senses the status of critical metabolites (e.g., oxygen, iron), thereby regulating hippocampal growth and function. We determined the effect of PIA and recombinant human erythropoietin (rHuEpo) treatment on mTOR signaling and expression of genes related to mTOR pathway functions. METHODS: Mice receiving an iron-supplemented diet were phlebotomized from postnatal day (P)3 to a target hematocrit of <25% by P7. Half were maintained at <25% until P14; half received rHuEpo from P7 to increase the hematocrit to 25–28%. Hippocampal phosphorylated to total protein ratios of 4 key mTOR pathway proteins were measured by Western blot at P14 and compared to nonphlebotomized, non-anemic control mice. mRNA levels of genes regulated by mTOR were measured by qPCR. RESULTS: PIA suppressed phosphorylation of all mTOR proteins. rHuEpo restored AMPK and AKT status, and partially rescued the mTOR output protein, S6K. PIA and rHuEpo treatment also altered expression of genes regulated by S6K. CONCLUSIONS: PIA compromises and rHuEpo treatment partially rescues a pathway regulating neuronal DNA transcription, protein translation and structural complexity.