Choroid plexus: Target for polypeptides and site of their synthesis

Abstract

Choroid plexus (CP) is an important target organ for polypeptides. The fenestrated phenotype of choroidal endothelium facilitates the penetration of blood‐borne polypeptides across the capillary walls. Thus, both circulating and cerebrospinal fluid (CSF)‐borne polypeptides can reach their receptors on choroidal epithelium. Several polypeptides have been demonstrated to regulate CSF formation by controlling blood flow to choroid plexus and/or the activity of ion transport in choroidal epithelium. However, many ligand‐receptor interactions occurring in the CP are not involved in the regulation of fluid secretion. Increasing evidence suggests that the choroidal epithelium plays an important role in hormonal signaling via a receptor‐mediated transport into the brain (e.g., leptin) and helps to clear certain CSF‐borne polypeptides (e.g., soluble amyloid β‐protein). Thus, impaired choroidal transport or insufficient clearance of polypeptides may contribute to pathogenesis of systemic or central nervous system (CNS) disorders, such as obesity or Alzheimer's disease. CP epithelium is not only a target but is also a source of neuropeptides, growth factors, and cytokines in the CNS. These polypeptides following their release into the CSF may exert distal, endocrine‐like effects on target cells in the brain due to bulk flow of this fluid. Distinct temporal patterns of choroidal expression of several polypeptides are observed during brain development and in various CNS disorders, including traumatic brain injury and ischemia. Therefore, it is proposed that the CP plays an integral role not only in normal brain functioning, but also in the recovery from the injury. This review attempts to critically analyze the available data to support the above hypothesis. Microsc. Res. Tech. 52:65–82, 2001. © 2001 Wiley‐Liss, Inc.

Neuroinflammatory response of the choroid plexus epithelium in fatal diabetic ketoacidosis

“…The numerous physiologic (Emerich et al, 2005) and immunologic (Chodobski et al, 2001) functions of the CP make it a candidate to play a role in the fatal BE of DKA. While we have no information on the onset or extent of the initial insult to the CP or the sequence of progression, we hypothesize that these neuroinflammatory factors are not involved in the initiation or early progression of subclinical BE (Hoffman et al, 1988;Durr et al, 1992), but rather during the clinical BE of DKA and may be the critical factor in a progressively edematous brain.…”

The Distributional Nexus of Choroid Plexus to Cerebrospinal Fluid, Ependyma and Brain

“…A steady supply of choroidally derived peptides (Chodobski and Szmydynger-Chodobska 2001), nucleosides (Redzic et al 2005), and vitamins Johanson 2006, 2007b) furnished to CSF is critical for feeding the periventricular regions (the domain harboring neurogenic stem cells) that drive normal brain development. Containing sparse capillary networks, the early fetal cortex evidently needs nutritional supplies delivered via CP-CSF as FIGURE 1.-Central role of the choroid plexus (CP)-cerebrospinal fluid (CSF) nexus in exchanging materials with brain.…”

A Comparative Proteomic Analysis of Human and Rat Embryonic Cerebrospinal Fluid

“…It has been described as an intermediary between blood and brain for the transport of nutrients and growth factors, and as a fluid buffer for the brain to protect both the brain and the large vessels that supply blood to the brain. 7,8 It has also been proposed to be involved in the elimination of toxins and other metabolic byproducts. 8,9 A mathematical analysis taking into account the pulsatile nature of CSF flow proposed that the CSF pulsations buffer the capillary bed from the effects of arterial pulsations that might otherwise prevent linear blood flow due to the mechanics of the brain being enclosed in the skull.…”