Intranasal Insulin Treatment Alters Gene Expression Profile in the Hippocampus of Rats with Perinatal Iron Deficiency

Background: Perinatal iron deficiency (ID) targets the hippocampus and leads to long-term cognitive deficits. These deficits remain even after iron repletion, suggesting that further insight into the mechanisms of cognitive deficits and adjunct treatments are needed. Intranasal insulin improves cognitive deficits in adult humans with Alzheimer’s disease and type 2 diabetes and could provide benefits in ID-induced neurological dysfunction. Objective: Assess the effects of intranasal insulin administration on the hippocampal transcriptome in rat model of perinatal ID. Methods: Perinatal ID was induced using a low iron diet from gestational day 3 until postnatal day (P) 7, followed by an iron sufficient (IS) diet through P21. Intranasal insulin was administered at a dose of 0.3 IU, twice daily from P8 to P21. Hippocampi were removed on P21 from IS control, ID control, IS insulin, and ID insulin groups. Total RNA was isolated and profiled using TruSeq next-generation sequencing (Illumina). Gene expression profiles were characterized using custom Galaxy workflows and expression patterns were examined using Ingenuity Pathways Analysis (Qiagen) (n = 7-9 per group). Results: Transcriptomic profiling revealed that mitochondrial biogenesis and flux, oxidative phosphorylation, quantity of neurons, CREB signaling in neurons, and RICTOR-based mTOR signaling were disrupted with ID and positively affected by insulin treatment with the most benefit observed in the ID insulin group. Conclusions: Both perinatal ID and insulin administration altered gene expression in the developing hippocampus. Intranasal insulin treatment reversed the adverse effects of ID on many molecular pathways and should be further explored as an adjunct therapy in perinatal ID. Iron deficienct rat pups were treated with intranasal insulin and compared with iron sufficent controls through RNA-seq profiling of the hippocampus.