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Uptake and Distribution of Iron and Transferrin in the Adult Rat Brain
Author(s) -
Morris C. M.,
Keith A. B.,
Edwardson J. A.,
Pullen R. G. L.
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb08904.x
Subject(s) - transferrin , choroid plexus , blood–brain barrier , chemistry , transferrin receptor , albumin , in vivo , permeability (electromagnetism) , vascular permeability , in vitro , biochemistry , endocrinology , medicine , biophysics , central nervous system , biology , microbiology and biotechnology , membrane
Brain uptake of iron‐59 and iodine‐125‐labelled transferrin from blood in the adult rat has been investigated using graphical analysis to determine the blood‐brain barrier permeability to these tracers in experiments that lasted between 5 min and 8 days. The blood‐brain barrier permeability ( K in ) to 59 Fe was 89 ± 10 −5 ml/min/g compared to the value of 7 ± 10 −5 ml/min/g for 125 I‐transferrin, which is similar to that of albumin, a plasma marker. The autoradiographic distribution of these tracers in brain was also studied to determine any regional variation in brain uptake after the tracers had been administered either system‐ically or applied in vitro. No regional uptake was seen for 125 I‐transferrin even after 24 h of circulation. In contrast, 59 Fe showed selective regional uptake by the choroid plexus and extra‐blood‐brain barrier structures 4 h after administration. After 24 h of circulation, 59 Fe distribution in brain was similar to the transferrin receptor distribution, as determined in vitro, but was unlike the distribution of non‐haem iron determined histochemically. The data suggest that brain iron uptake does not involve any significant transcytotic pathway of transferrin‐bound iron into brain. It is proposed that the uptake of iron into brain involves the entry of iron‐loaded transferrin to the cerebral capillaries, deposition of iron within the endothelial cells, followed by recycling of apotransferrin to the circulation. The deposited iron is then delivered to brain‐derived transferrin for extracellular transport within the brain, and subsequently taken up via transferrin receptors on neurones and glia for usage or storage.