Blood-Brain Barrier

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blood-brain barrier

[¦bləd ¦brān ′bar·ē·ər]
A barrier to the entry of substances from the blood into brain tissue; believed to be formed primarily by the endothelial cells of the brain vasculature.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Blood-Brain Barrier


a physiological mechanism that regulates the exchange of substances between the blood, the cerebrospinal fluid, and the brain.

The concept of the blood-brain barrier was introduced by the Soviet physiologist L. S. Shtern and the Swiss scientist R. Gauthier in 1921. Like other blood-tissue barriers,” the blood-brain barrier performs protective functions by preventing certain foreign substances introduced into the blood or the products of faulty metabolism formed in the body itself from penetrating the central nervous system. The state of the brain and spinal cells, which are particularly sensitive even to slight fluctuations in the composition and physicochemical properties of the environment, depends largely upon the permeability of the blood-brain barrier in the blood-to-brain and brain-to-blood directions. The idea of the blood-brain barrier as a single mechanism is being reexamined. A complex and varied system of specific formations has been found to function in the brain. The anatomical, physiological, physicochemical, and biological characteristics of these formations ensure their barrier properties. Various substances needed for the nutrition and activity of neural formations, which differ both in structure and in chemical composition, penetrate from the blood into the central nervous system through various sections of the blood-brain barrier. The walls of the brain capillaries and precapillaries and the vascular plexuses of the cerebral ventricles, neuroglia, and meninges constitute the anatomical elements of the blood-brain barrier. The so-called ground substance, which is found between the cells of the capillary walls and which consists of complexes of proteins and polysaccharides, plays an important part in the performance of the barrier functions. The condition of this substance largely determines the permeability of the blood-brain barrier.

Stains, salts, organic and inorganic compounds, and radioactive isotopes of phosphorus, iodine, and bromine are used to investigate the state of the blood-brain barrier.

The blood-brain barrier prevents not only injurious substances but also drugs, such as arsenic, mercury, bismuth compounds, and certain antibiotics, from penetrating the central nervous system, a fact that makes it difficult to treat certain brain diseases. Various methods are employed both in experiments and in the clinic to increase the permeability of the blood-brain barrier or to bypass it by injecting chemical substances into the cerebral ventricles or spinal canal.


Shtern, L. S. “Neposredstvennaia pitatel’naia sreda organov i tkanei.… ” In Izbr. trudy. Moscow, 1960.
Kassil’, G. N. Gemato-entsefalicheskii bar’er. Moscow, 1963.
Fiziologiia i patologiia gisto-gematicheskikh bar’erov. Moscow, 1968. Pages 170-254.
Bakay, L. The Blood-Brain Barrier. Springfield, Ill., 1956.
Tschirgi, R. D., “The Blood-Brain Barrier.” In Biology of Neuroglia. Springfield, Ill., 1958.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In addition, there are few drugs/compounds which increase the permeability of the blood brain barrier [25] temporarily by increasing the osmotic pressure in the blood which loosens the tight junctions between the endothelial cells.
Normally, brain capillary endothelial cells possess insulin-independent, GLUT-1 glucose transporters which mediate the facilitated diffusion of glucose through the blood brain barrier [44, 46].
Contrary to this, nonessential fatty acids cannot come across the blood brain barrier but essential fatty acids are transported across the barrier.
In other areas of the body, the water permeability of capillary membranes is quite low, because pores or slits are lacking in the blood brain barrier and it greatly limits water movement by the intercellular pathway.
Unfortunately, in the brain, there is no barrier for ethanol and it crosses the blood brain barrier very easily.
Thus, specific transport systems are required for carrying vitamins across blood brain barrier (Table 3).
Vitamin C crosses the blood brain barrier in the oxidized form through the glucose transporters [82].
Since it has no difficulty passing through the blood brain barrier, this becomes an additional source of cerebral stimulation.
Ultrasound waves will then be delivered to oscillate the microbubbles causing temporary disruption of the blood brain barrier.
In addition, the researchers observed that copper provoked inflammation of brain tissue which may further promote the breakdown of the blood brain barrier and the accumulation of Alzheimer's-related toxins.
The blood brain barrier protects the brain from foreign substances that may cause damage, protects the brain from hormones and neurotransmitters, and maintains a constant environment for the organ.
They found their method provided a semi-permeable window in the blood brain barrier that allowed higher molecular drug delivery - the membranes were able to deliver the molecules to the brain 1,000 times more effectively than when the barrier is in place.