Choroid plexus

The epithelium of the choroid plexus with its basal labyrinth (Fig. 249) is similar in many of its ultra-structural features to the epithelium of the renal tubule, and to other cellular structures that participate in transport. 

Macrophage-like cells which morphologically resemble epiplexus cells and which are very abundant within the coimective tissue stroma and also between the epithelial cells of all choroid plexuses of Macaca mulatta, are thought to be monocytes (Merker 1972). 

Very strong immunoreactivity for CYP2D was observed in the endothehal cells of the choroid plexus of the Wistar rat (Miksys et al. 2000). 

Lagrange etal. (1994) found significant amounts of superoxide anion production (measured by spectrometric recording of reduction of acetylates ferricytochrome c at 550 nm) in homogenates of rats choroid plexus incubated with 2,5-dimethyl benzoquinone (109.3 nM/min/NADPH-cytochrome P450 reductase activity) or menadione (100 nM/min/NADPH-cytochrome P450 reductase activity). 

Melatonin can have stimulatory actions in vivo on the choroidal ependymal cells in golden hamsters increase in cytoplasmic volume, increase in nuclear volume, increase in mitochondrial area or volume per cell, and increase in length of apical (ventricular) microvilli (Decker and Quay 1982). All of these ultrastructural effects were statistically 

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Localization CNS Cortex, hippocampus, striatum, olfactory bulb, spinal cord CA/S not present in adult. CNS Choroid plexus, medulla, pons, striatum, hippocampus (CA1, CA3), hypothalamus, spinal cord CNS Striatum, hippocampus (CA1), substantia nigra, globus pal-lidus. CNS Striatum, brainstem, thalamus, hippocampus, olfactory bulb, substantia nigra... 

Kidney glomeruli, GI tract mucosa, exocrine and endocrine glands, certain tumors, pertibular capillaries, choroid plexus, pancreas, intestinal wall Sinusoidal... 

Matsumoto, N, Kitayama, H, Kitada, M, Kimura, K, Noda, M, and Ide, C, 2003. Isolation of a set of genes expressed in the choroid plexus of the mouse using suppression subtractive hybridization. Neuroscience 117,405-415. 

Embedded within the brain are four ventricles or chambers that form a continuous fluid-filled system. In the roof of each of these ventricles is a network of capillaries referred to as the choroid plexus. It is from the choroid plexuses of the two lateral ventricles (one in each cerebral hemisphere) that cerebrospinal fluid (CSF) is primarily derived. Due to the presence of the blood-brain barrier, the selective transport processes of the choroid plexus determine the composition of the CSF. Therefore, the composition of the CSF is markedly different from the composition of the plasma. However, the CSF is in equilibrium with the interstitial fluid of the brain and contributes to the maintenance of a consistent chemical environment for neurons, which serves to optimize their function. 

Achen, M. G., et al. (1992). Protein synthesis at the blood-brain barrier. The major protein secreted by amphibian choroid plexus is a lipocalin. J. Biol. Chem. 267, 23170-4. 

Bobillier, P., el at (1982). Glucose utilization increases in choroid plexus during slow wave sleep. A [14C] deoxyglucose study in the cat. Brain Res. 240, 359-63. 

Irikura, D., et at. (2007). Characterization of a major secretory protein in the cane toad (Bufo marinus) choroid plexus as an amphibian lipocalin-type prostaglandin D synthase. J. Biochem. 141, 173-80. 

Urade, Y., el al. (1993). Dominant expression of mRNA for prostaglandin D synthase in leptomeninges, choroid plexus, and oligodendrocytes of the adult rat brain. Proc. Natl. Acad. Set USA 90, 9070-4. 

Sweet, D. H., Miller, D. S., Pritchard, J. B., Fujiwara, Y., Beier, D. R., Nigam, S. K., Impaired organic anion transport in kidney and choroid plexus of organic anion transporter 3 (Oat3 (Slc22a8)) knockout mice, J. 

Gao B, Meier PJ. Organic anion transport across the choroid plexus. Microsc Res Tech 2001 52(l) 60-64. 

Novotny A, Xiang J, Stummer W, Teuscher NS, Smith DE, Keep RF. Mechanisms of 5-aminolevulinic acid uptake at the choroid plexus. J Neurochem 2000 75(1) 321—328. 

Teuscher NS, Novotny A, Keep RF, Smith DE. Functional evidence for presence of PEPT2 in rat choroid plexus studies with glycylsarcosine. J Pharmacol Exp Ther 2000 294(2) 494-499. 

Rao W, Dahlheimer JL, Bardgett ME, Snyder AZ, Finch RA, Sartorelli AC et al. Choroid plexus epithelial expression of MDR1 P glycoprotein and multidmg resistance-associated protein contribute to the blood-cerebrospinalfluid drug-permeability barrier. Proc Natl Acad Sci USA 1999 96(7) 3900-3905. 

Wijnholds J, deLange EC, Scheffer GL, van den Berg DJ, Mol CA, van d, V et al. Multidrug resistance protein 1 protects the choroid plexus epithelium and contributes to the blood-cerebrospinal fluid barrier. J Clin Invest 2000 105(3)779-285. 

Fig. 15.1 D iagram showing a longitudinal cross-section of the blood-cerebrospinal fluid barrier at the choroid plexus. This barrier is formed by epithelial or choroid cells held together at their apices by tight junctions. The...

Spector R, Johanson CE. The mammalian choroid plexus. Sci American 1989 61 68-74. 

The exit of drugs from the CNS can involve (1) diffusion across the blood-brain barrier in the reverse direction at rates determined by the lipid solubility and degree of ionization of the drug, (2) drainage from the cerebrospinal fluid (CSP) into the dural blood sinuses by flowing through the wide channels of the arachnoid villi, and (2) active transport of certain organic anions and cations from the CSF to blood across the choroid plexuses... 

FIGURE 5-3 Immunocytochemical localization of the Na,K pump in choroid plexus. Choroid plexus contains epithelial cells with intensely stained microvillar and intermicrovillar plasma membranes. The basal and lateral plasma membrane surfaces are not stained. Bar = 2 im. (With permission from reference [81].)... 

The aquaporin isoforms have different distributions in various tissues or organs and often the site of localization suggests the function. The aquaporins so far found in brain are AQP1 in choroid plexus AQP4 in astrocytic processes and AQP9, an aquaglycerol transporter, in astrocytes. Neurons have not yet been found to contain any aquaporin. 

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