Observations on exsudation of fibronectin, fibrinogen and albumin in the brain after carotid infusion of hyperosmolar solutions

Abstract

An immunohistochemical study was carried out on rat brain to determine if a transient opening of the blood-brain barrier (BBB), leading to extravasation of serum albumin, is also associated with exudation and cellular uptake of fibronectin and fibrinogen. Both of them might exert important biological effects provided that they pass the BBB and come into contact with cells of the brain parenchyma. Hyperosmolar solutions of urea or mannitol were infused in the carotid artery for 30 s to open the BBB and the animals were killed at various time intervals thereafter. Formaldehyde-fixed, paraffin-embedded material was used for immunohistochemical demonstration of extravasated proteins by an avidin-biotin peroxidase technique. Multifocal, often confluent areas of widely different sizes with signs of albumin extravasation were observed both in the grey and the white matter of the cerebral hemispheres exposed to the hyperosmolar solutions. Much less pronounced changes were observed in rats given an intracarotid saline infusion alone. Immunoreactive material indicating extravasation of fibronectin and fibrinogen was present in the infused cerebral hemispheres but albumin immunoreactivity was much more widespread. Reaction product was observed in vascular walls, presumably in extracellular spaces and in nerve cells. Immunoreactivity in the perikaryon of neurons formed different patterns in various cells. A granular type most probably represents accumulation of the proteins in lysosomal organelles after pinocytotic uptake into the neuron. The second so-called diffuse variety is presumably the result of a severe nerve cell injury with an uncontrolled leakage of proteins into the cytoplasm. Our results indicate that vascular walls, extracellular spaces, glial cells and neurons will be exposed to extravasated fibronectin and fibrinogen as well as to albumin and that antigenic sites in such compounds remain for a long period after the BBB opening. In addition, there are indications that carotid infusions of hyperosmolar solutions may cause nerve cell injuries in regions with BBB opening. These findings have obvious clinical and experimental significance.

A quantitative immunocytochemical study of the osmotic opening of the blood-brain barrier to endogenous albumin

“…Finally, it should be emphasized that our present observations corroborate the previously reported findings from light microscopy (Klatzo et al, 1980;Salahuddin et al, 1988;Liu et al, 1989;Broadwell & Sofroniew, 1993) and electron microscopy studies (Maeda et al, 1992;Vinores et al, 1993;Guy et al, 1994), indicating that endogenous albumin can be utilized successfully as a natural macromolecular tracer in studies of the normal or disturbed BBB. The important advantage of the immunogold procedure used in our study is its high efficiency, excellent visibility of immunosignals, and usefulness for quantitative evaluation and morphometric and statistical analysis.…”

Neuropsychiatric systemic lupus erythematosus persists despite attenuation of systemic disease in MRL/lpr mice

“…The ability of IgG and various leukocytes to effectively target the CNS is indicative of BBB pathology in MRL/lpr mice [ 8 , 30 ]. In the present study, BBB disruption was assessed by extravasation of fibronectin, a serum protein not widely distributed in the CNS [ 31 ]. Fibronectin leakage was observed across the BBB in over half of MRL/+ → MRL/lpr and MRL/lpr → MRL/lpr chimeras, while no evidence of leakage was found in MRL/+ → MRL/+ mice (F 4,27 = 4.25; p = 0.01, Fig.…”

The presence of 4-hydroxynonenal/protein complex as an indicator of oxidative stress after experimental spinal cord contusion in a rat model

“…1,9 Like IgG, additional plasma proteins, for example, fibronectin, fibrinogen, and albumin, are taken up by cells after breach of the blood-CNS barrier. 32 It has been suggested that cellular IgG staining is artifactual, although some investigators speculate that such a staining pattern may indicate cell membrane damage. 30 This observed similarity between IgG and HNE/protein conjugates is consistent with the hypothesis of a causal relationship between BSCB breach and oxidative stress.…”