From:Multiplicity of cerebrospinal fluid functions: New challenges in health and disease
A |
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Aquaporin 1 (Blood-CSF Interface) |
Aquaporin 4 (Blood-Brain Interface) |
AQP1 is present at the CSF-facing pole of choroid plexus epithelium [70 – 73, 77, 78], and in the CSF-brain ependymal lining [281]. |
AQP4 is located in astrocytic foot processes at the BBB. It is associated with fluid transfer across cerebral microvessels. |
Reduced expression in choroid plexus is associated with slower rates of CSF secretion and thus decreases ICP [77, 78]. |
Elevated expression of AQP4 in the BBB occurs in chronic hydrocephalus [281 – 283]; may be associated with fluid reabsorption. |
Attenuated expression in aging [57] and in Alzheimer's disease is accompanied by slower fluid turnover rate [79]. |
Diminished expression at BBB leads to a reduction in brain edema formation in some animal models. |
B |
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LRP-1(Low density lipophilic receptor associated protein) |
RAGE(Receptor for advanced glycation end products) |
Expressed in choroidal epithelium and capillary endothelium [229, 257]. |
Expressed in choroidal epithelium and brain capillary endothelium [257]. |
Removes Aβ peptide from CSF and brain ISF [229, 243] for excretion via blood. |
Transports Aβ from blood into brain ISF where the retained peptide may predispose to Aβ plaque formation in the interstitium. |
Sustained or increased expression in choroid plexus during aging, NPH and AD. |
Enhanced expression of RAGE at BBB in aging, NPH [219] and AD [225] may destabilize BBB and precipitate plaque. |
Decreased expression of LRP-1 at the BBB in aging, NPH and AD likely interferes with Aβ removal [219, 225, 229]. |
Expression of RAGE is generally opposite to that of LRP-1 at the barriers and in neurons [225]. |