Regional uptake and redistribution of ⁵⁴Mn and ⁵⁹Fe in brains of hypotransferrinemic and iron-deficient mice

To investigate the role of transferrin in Mn and Fe uptake into the brain we used a hypotransferrinemic strain of mice and manipulated dietary Fe. In this experiment, we tested the hypothesis that transferrin may have a role in the regional uptake and redistribution of these metals within the brain. We fed diets either adequate or deficient in Fe to weanling mice heterozygotic for the hypotransferrinemia mutation (Hh) and wild-type BALB/cj mice for eight weeks in order to manipulate transferrin concentrations and saturations. Either 1 h or 1 wk before killing, mice were injected with 40 μCi of either ⁵⁴MnCl₂ or ⁵⁹FeCl₃ iv; regional distribution of tracers was assessed by autoradiography. Levels of ⁵⁴Mn in brain 1 wk after injection were 2.5-fold higher than the values 1 h after injection regardless of strain or dietary Fe. Brain uptake of ⁵⁴Mn after 1h was localized primarily in choroid plexus. After 1 wk ⁵⁴Mn diffused from choroid plexus, with signal then being seen in the granular layer of cerebellum, brain stem, hippocampus, and cerebral cortex. There were no significant strain or Fe status effects on total ⁵⁴Mn content of brain or its distribution at either time point. We conclude that transferrin has no effect on the brain distribution of iv Mn. Preliminary data indicate that ⁵⁹Fe is distributed in choroid plexus of Fe-adequate and -deficient wild-type mice 1 wk after injection.