Abstract

The highly selective permeability of cerebral blood vessels, termed the blood-brain barrier, is due to endothelial tight junctions (zonulae occludentes). Hyperosmotic solutions reversibly open the blood-brain barrier. The purpose of this study is to determine the immediate effect of hyperosmotic arabinose perfusion upon the cerebrovascular endothelium, the morphology of the cerebral cortex, and the cortical extracellular space.

Twelve adult male Sprague-Dawley rats were separated into three groups of four animals each: control, intermediate, and extreme. Controls were perfused with a Tyrode's solution prewash followed by trialdehyde fixative. The intermediate group received a prewash of 740 mmol/kg arabinose followed by the trialdehyde fixative, which also contained 740 mmol/kg arabinose. The extreme group had an arabinose prewash (1400 mmol/kg) preceding their fixative-arabinose perfusate. Tissue samples were obtained from occipital, parietal, and temporal lobes of the brain. These were postfixed by 1% osmium tetroxide in 0.1M sodium cacodylate buffer.

Electron microscopic examination revealed no observable morphological differences among the three areas of the cortex within each of the groups. The cortex of control animals showed little extracellular space among tightly packed processes in the neuropil. The endothelium of the cerebral vessels was well preserved, and interendothelial junctions were normal in appearance. Neurons and neuroglia were typical with good preservation of cellular organelles.

Tissues from intermediate and extreme groups showed a marked increase in extracellular space. Cells and neuropil were shrunken, especially in the extreme group. Microtubules appeared partially dissociated. Vessel endothelium was condensed, and in the extreme group exhibited numerous areas of thinning. Most interendothelial junctions were pulled apart and interendothelial clefts were widened. More abluminal pinocytotic vesicles were observed along vessels in both hyperosmotic groups than in the controls.

Conspicuous changes of interendothelial junctions appeared within both hyperosmotic groups. Hyperosmotic solutions cause a net movement of water into the vessels, resulting in shrinkage of surrounding tissue and of the endothelium itself. The higher the concentration of arabinose, the greater the degree of shrinkage and amount of extracellular space produced.

LLU Discipline

Anatomy

Department

Anatomy

School

Graduate School

First Advisor

Robert L. Schultz

Second Advisor

John W. Patrickson

Third Advisor

George Maeda

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1987

Date (Title Page)

12-1987

Language

English

Library of Congress/MESH Subject Headings

Blood-Brain Barrier; Extracellular Space; Brain -- physiology

Type

Thesis

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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