Blood-Brain Barrier Permeability Using Tracers and Immunohistochemistry

互联网2014-02-14

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The first report of blood-brain barrier (BBB) permeability by Paul Ehrlich (1 ) involved the use of the exogenous tracer Coerulean-S as described in Chapter 6 . Over the years, tracers of different sizes were introduced to study the permeability properties of normal cerebral vessels in physiologic and pathologic states (Table 1 ). Tracers provide information about the permeability status of vessels immediately before sacrifice. The disadvantage of exogenous tracers is that there are side effects associated with the administration of some tracers in live animals. The properties and methods by which some of these tracers are used to study BBB permeability to proteins and ions in pathologic states will be described.

Table 1 The Exogenous Tracers Used to Detect Blood-Brain Barrier Permeability and the Methods to Detect Endogenous Protein Extravasations

I. Exogenous Tracers
1. Markers of Protein Permeability
Dyes: Evans blue
Fluorescent Tracers:
Fluorescein isothiocynate-dextran (MW: 62,000)
Fluorescein isothiocynate-albumin (MW: 67,000)
Horseradish peroxidasundefined (MW: 40,000)
Microperoxidasundefined (MW: 1900)
Radiolabeled Compounds
125Idine-labeled serum albumin
¹⁴ C-labeled dextran (MW: 70,000)
2. Markers of Solute and Ion Permeability
Ionic Lanthanuundefined (MW: 138.9)
Sodium Fluorescein (MW: 376)
Lucifer Yellow (MW: 457)
Ruthenium Reundefined (MW: 800)
Fluorescein isothiocynate-dextran (MW: 3000)
Radio-labeled Compounds
¹⁴ C-α -Aminoisobutyric acid (MW 103)
¹⁴ C Sucrose (MW: 342)
¹⁴ C- Methotrexate (MW: 455)
¹⁴ C-Inulin (MW: 5000)

II.Endogenous Protein Extravasation
Detected of Plasma Proteins by Immunohistochemistry
Immunoperoxidase
Immunofluorescence
Immunogold technique

The molecular weights of the tracers are expressed in Daltons.

~undefinedExogenous tracers detectable with EM.