Regional dissection and determination of loosely bound and non-heme iron in the developing mouse brain

Iron is a trace metal essential for normal brain development but toxic in excess as it is capable of generating highly reactive radicals that damage cells and tissue. Iron is stringently regulated by the iron regulatory proteins, IRP1 and IRP2, which regulate proteins involved in iron homeostasis at the posttranscriptional level. In this study, 12 distinct regions were microdissected from the mouse brain and regional changes in the levels of loosely bound and non-heme iron that occur with development were measured. We examined 6, 12, and 24 week old wildtype C57BL/6 mice and mice with a targeted deletion of iron regulatory protein 2 (IRP2-/-) that have been reported to develop neurodegenerative symptoms in adulthood. In wildtype mice, levels of loosely bound iron decreased while non-heme iron increased with development. In contrast, an increase in loosely bound and a more pronounced increase in non-heme iron was seen in IRP2-/- mice between 6 and 12 weeks of age, stemming from lower levels at 6 weeks (the youngest age examined) compared to wildtype. These results have implications for understanding the increase in regional brain iron that is associated with normal aging and is postulated to be exacerbated in neurodegenerative disorders.