Neurobiol Lipids 1, 2 (15 July 2002) find out how to cite this article

Shlomo Yehuda

Psychopharmacology Lab., Bar Ilan University, Ramat Gan 52900, Israel
tel: (972 3) 535-3327, fax: (972 3) 535-3327, email: Yehudas@mail.biu.ac.il ; shlomoyehuda@neurobiologyoflipids.org

Published online: 15 July, 2002 | Article readership

Copyright © 2002 S Yehuda, Licensee Neurobiology of Lipids

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FIRST PARAGRAPH INTRODUCTION EXPERIMENTAL APPROACHES

AN EXAMPLE OF THE INTEGRATED APPROACH PROSPECT SUGGESTED BIBLIOGRAPHY

The number of studies and scientific papers, which can be classified as related to the general area of neurobiology of lipids, has constantly grown during years. The "popularity" of the field is based not only on new technology and research tools, but also on the emergence of new theoretical avenues.

One group of molecules in particular, the polyunsaturated fatty acids (PUFA), seems to play an important role in each of these three systems (neurological, immunological, and endocrinological systems). Previous studies have shown that PUFA has a profound effect in all three systems, such as altering neuronal membrane fluidity and in the production and function of neurotransmitters. PUFA has also been shown to modify the production and activity of releasing factors and certain hormones, as well as the activity of certain cytokines.

The central hypothesis of this note is that PUFA occupies a major role in being able to modify the activity of each system and the interaction between them. Psychological functions, such as cognition, learning, mood, stress, pain and brain related states or clinical neurological disorders, could be best understood by appreciating the unifying elements of these systems.

Few topics in nutrition cause as much controversy and concern, and are as widely misunderstood, as fat. The dominant message from the medical profession has been to drastically reduce the amount of fat we eat, in the interest of combating risks associated with cardiovascular disorders, diabetes, and other chronic disorders. At the same time, deficiencies in fat intake are equally likely to contribute to health hazards, including increased risk of infection, dysregulation of chronobiological activity, and impaired cognitive and sensory functions (especially in infants).  A consensus has emerged from recent research suggesting that it is not so much the amount of fat we eat, as the balance of the different types of fats. The type of dietary fat affects the behavior of each cell, that is, how well it can perform its vital functions and the ability to resist disease.

The two polyunsaturated fatty acids (PUFA), linoleic and a-linolenics acid, are necessary for good health.  Referred to as "essential fatty acids" (EFA) because the body cannot manufacture them, but is dependent on their being provided through nutritional intake, EFAs have beneficial effects when available in moderation. Excesses of the otherwise beneficial fatty acids may, however, exert harmful effects, with high intakes of saturated and hydrogenated fats being linked to an increase in a number of health risks, including degenerative diseases, cardiovascular disease, cancer and diabetes.

Linoleic acid is a member of the omega-6 (n-6) fatty acids family, while a-linolenic acid belongs to the omega-3 (n-3) fatty acids. These terms refer to characteristics in the chemical structure of the fatty acids. Other omega-6 fatty acids can be manufactured in the body using linoleic acid as a starting point. These include gamma-linoleic acid (GLA), dihomo-gamma-linoleic acid (DHGLA) and arachidonic acid (AA). Similarly, other omega-3 fatty acids that are manufactured in the body using alpha linolenic acid as a starting point, include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Essential fatty acids are involved in energy production, the transfer of oxygen from the air to the bloodstream, and the manufacture of hemoglobin. They are also involved in growth, cell division and nerve function. Essential fatty acids are found in high concentrations in the brain and are essential for normal nerve impulse transmission and brain function.

Among the significant components of cell membranes are the phospholipids, which contain fatty acids. The type of fatty acids in the diet determines the type of fatty acids present in cell membranes. A phospholipid made from a saturated fat has a different structure and is less fluid than one that incorporates an essential fatty acid. In addition, linoleic and a-linolenic acids per se have an effect on the neuronal membrane fluidity index. They are able to decrease the cholesterol level in the membrane yielding the decrease of membrane fluidity. This would make it difficult for the cell to carry out its normal functions, and increase the cell's susceptibility to injury and death. These consequences for cell function are not restricted to absolute levels of FAs, rather the relative amounts of omega-3 fatty acids and omega-6 fatty acids in cell membranes have also been shown to affect cellular function.

At least five categories of PUFA effects on brain functions have been noted and discussed previously, namely:
 
 

A	modifications of membrane fluidity;
B	modifications of the activity of membrane bound enzymes;
C	modifications of the number and affinity of receptors;
D	modifications of the function of ion channels; and
E	modifications of the production and activity of neurotransmitters.

Symptoms of essential fatty acid deficiency may include fatigue, skin problems, immune weakness, gastrointestinal disorders, heart and circulatory problems, growth retardation, and sterility. In addition to these symptom conditions, a lack of dietary essential fatty acids has been implicated in the development or aggravation of breast cancer, prostate cancer, rheumatoid arthritis, asthma, pre-eclampsia, depression, schizophrenia and ADHD (attention deficit/hyperactivity disorder). This list is neither exhaustive nor conclusive.

The establishment of a journal, which is devoted to the neurobiology of lipids, will certainly enhance the awareness of the scientific community to this important issue, and will serve as a focal point for information and ideas being exchanged between scientists from different scientific disciplines.
 
 

1. Mostofsky DI, Yehuda S, Salem N. (Eds.)  Fatty acids: Physiological and Behavioral Functions, Humana Press, Totowa, N.J. (2001)  [ Book details at Amazon.com ][ Book details at Humana Press ].

2. Hillbrand M, Spitz RT. (Eds.) Lipids, Health and Behavior. American Psychological Association. Washington, D.C. (1997) [ Book details at Amazon.com ].

3. Simopoulos AP, Robinson J. The Omega Diet. HarperCollins, New York, N.Y. (1999) [ Book details at Amazon.com ].

4. Stoll AL. The Omega-3 Connection. Fireside Book. New York, N.Y. (2001) [ Book details at Amazon.com ].

5. Udo E. Fats that Heal, Fats that Kill, Alive Books, Vancouver, Canada (1997) [ Book details at Amazon.com ].

6. Yehuda S, Mostofsky DI. Handbook of Essential Fatty Acids: Biochemistry, Physiology and Behavioral Neurobiology.  Humana Press, Totowa, N.J. (1997) [ Book details at Amazon.com ][ Book details at Humana Press ].
 

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This article should be cited in the following way: Yehuda S. Opening note commentary: Neurobiology of lipids. Neurobiol. Lipids  Vol.1, 2 (2002), Published online July 15, 2002, Available at: http://neurobiologyoflipids.org/content/1/2/ Please note: Because Neurobiology of Lipids is published online only,  the articles are identified with an article number rather than with traditional (printed) page numbers