Vulnerability of adult hippocampus to toxicity after postnatal exposure of nursing male albino rats to iron overload : Histomorphometric and ultrastructural study

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Background: The association of iron overload with neurodegenerative diseases and cognitive deficits in aging were previousreported. Developing hippocampus is highly sensitive to changes in iron homeostasis that might lead to long term irreversibleimpact on its functions.Objective: To examine the possible histopathological changes in adult hippocampal subregions CA1, CA3 and DG subjectedto excess iron administration at critical early postnatal life.Materials and Methods: 20 male rat pups weighing 50-55gm were selected and randomly divided into 2 groups (10 per each).The control received 0.5 ml normal saline intraperitoneally once daily for 21 consecutive days. Iron treated group receivedintraperitoneal injection of ferrous sulfate dissolved in 0.5 ml normal saline at a dose of 3 mg/kg/day for 21 days. Aftersacrifice, brain specimens were processed for histomorphometric and ultrastructural study.Results: Iron deposits were reported only in treated group using Prussian blue. Obvious degeneration of principal neurons withsignificant decrease in their number and increased immunoreactivity to caspase 3 and glial fibrillary acid protein (GFAP)wereobserved in all studied subfields of iron treated hippocampus. Astrogliosis, astrocyte damage and disruption of blood brainbarrier were also noticed.Conclusion: There was pronounced degenerative changes in all studied subregions of iron treated hippocampus indicating itsextreme sensitivity to changes in iron homeostasis, hence iron overload could be considered highly toxic insult on growinghippocampal tissue.