The choroid plexus removes beta-amyloid from brain cerebrospinal fluid

Exp Biol Med (Maywood). 2005 Nov;230(10):771-6. doi: 10.1177/153537020523001011.


beta-Amyloid (Abeta) concentration in the cerebrospinal fluid (CSF) of the brain may be regulated by the choroid plexus, which forms a barrier between blood and brain CSF. Abeta uptake from CSF was determined as its volume of distribution (V(D)) into isolated rat choroid plexus tissue. The V(D) of [125I]Abeta1-40 was corrected by subtraction of the V(D) of [14C]sucrose, a marker for extracellular space and diffusion. Abeta uptake into choroid plexus was time and temperature dependent. Uptake of [125I]Abeta was saturable. Abeta uptake was not affected by addition of transthyretin or apolipoprotein E3. In studies with primary culture monolayers of choroidal epithelial cells in Transwells, Abeta permeability across cells, corrected by [(14)C]sucrose, was greater from the CSF-facing membrane than from the blood-facing membrane. Similarly, cellular accumulation of [125I]Abeta was concentrative from both directions and was greater from the CSF-facing membrane, suggesting a bias for efflux. Overall, these results suggest the choroid plexus selectively cleanses Abeta from the CSF by an undetermined mechanism(s), potentially reducing Abeta from normal brains and the brains of Alzheimer's disease patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amyloid beta-Peptides / blood
  • Amyloid beta-Peptides / cerebrospinal fluid*
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Biological Transport
  • Biomarkers / cerebrospinal fluid
  • Blood-Brain Barrier
  • Brain / metabolism*
  • Carbon Radioisotopes
  • Cells, Cultured
  • Cerebrospinal Fluid / metabolism*
  • Cerebrovascular Circulation
  • Choroid Plexus / cytology
  • Choroid Plexus / metabolism*
  • Iodine Radioisotopes
  • Kinetics
  • Male
  • Peptide Fragments / blood
  • Peptide Fragments / cerebrospinal fluid*
  • Peptide Fragments / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Sucrose / metabolism
  • Temperature


  • Amyloid beta-Peptides
  • Biomarkers
  • Carbon Radioisotopes
  • Iodine Radioisotopes
  • Peptide Fragments
  • amyloid beta-protein (1-40)
  • Sucrose