Intranasal deferoxamine attenuates synapse loss via up-regulating the P38/HIF-1α pathway on the brain of APP/PS1 transgenic mice

The widely recognized neuroprotective effect of iron chelators is contributed by their ability to prevent reactive oxygen species (ROS) generation via the Fenton reaction, which sequesters redox-active Fe. An additional neuroprotective mechanism of iron-chelating compounds is to regulate the transcriptional activator hypoxia-inducible factor 1 alpha (HIF-1 alpha). In the present study, we observed that intranasal administration of deferoxamine decreased beta-amyloid (A beta) deposition and rescued synapse loss in the brain of A beta precursor protein and presenilin-1 (APP/PS1) double transgenic mice. We found that deferoxamine (DFO) up-regulated HIF-1 alpha mRNA expression and its protein level, and further induced the proteins that are encoded from HIF-1-adaptive genes, including transferrin receptor (TFR), divalent metal transporter 1 (DMT1), and brain-derived neurotrophic factor (BDNF). The effects of DFO on the induction and stabilization of HIF-1 alpha were further confirmed in vitro. This was accompanied by a decrease of Fe in the CA3 region of the hippocampus. Western blotting studies revealed that DFO differentially enhanced the phosphorylation of mitogen-activated protein kinase (MAPK)/P38 kinase in vitro and in vivo. The results suggest that the DFO may up-regulate several HIF-1-dependent neuroprotective-adaptive genes in AD via activating P38/HIF-1 alpha pathway, which may serve as important therapeutic targets to the disease.