Restless legs syndrome is a neurological disorder characterized by an urgency to 
move the legs during periods of rest. Data from a variety of sources provide a 
compelling argument that the amount of iron in the brain is lower in individuals 
with restless legs syndrome compared with neurologically normal individuals. 
Moreover, a significant percentage of patients with restless legs syndrome are 
responsive to intravenous iron therapy. The mechanism underlying the decreased 
iron concentrations in restless legs syndrome brains is unknown. We hypothesize 
that the source of the brain iron deficit is at the blood-brain interface. Thus 
we analysed the expression of iron management proteins in the epithelial cells 
of the choroid plexus and the brain microvasculature in post-mortem tissues. The 
choroid plexus, obtained at autopsy, from 18 neurologically normal controls and 
14 individuals who had primary restless legs syndrome was subjected to 
histochemical staining for iron and immunostaining for iron management proteins. 
Iron and heavy chain ferritin staining was reduced in the epithelial cells of 
choroid plexus in restless legs syndrome. Divalent metal transporter, 
ferroportin, transferrin and its receptor were upregulated in the choroid plexus 
in restless legs syndrome. Microvessels were isolated from the motor cortex of 
11 restless legs syndrome and 14 control brains obtained at autopsy and 
quantitative immunoblot analyses was performed. Expression of heavy chain 
ferritin, transferrin and its receptor in the microvessels from restless legs 
syndrome was significantly decreased compared with the controls but divalent 
metal protein 1, ferroportin, prohepcidin, mitochondrial ferritin and 
light-chain ferritin remained unchanged. The presence of an iron regulatory 
protein was demonstrated in the brain microvasculature and the activity of this 
protein is decreased in restless legs syndrome; a finding similar to our earlier 
report in neuromelanin cells from the substantia nigra of restless legs syndrome 
brains. This study reveals that there are alterations in the iron management 
protein profile in restless legs syndrome compared with controls at the site of 
blood-brain interface suggesting fundamental differences in brain iron 
acquisition in individuals with restless legs syndrome. Furthermore, the 
decrease in transferrin receptor expression in the microvasculature in the 
presence of relative brain iron deficiency reported in restless legs syndrome 
brains may underlie the problems associated with brain iron acquisition in 
restless legs syndrome. The consistent finding of loss of iron regulatory 
protein activity in restless legs syndrome brain tissue further implicates this 
protein as a factor in the underlying cause of the iron deficiency in the 
restless legs syndrome brain. The data herein provide evidence for regulation of 
iron uptake and storage within brain microvessels that challenge the existing 
paradigm that the blood-brain barrier is merely a transport system.