ABSTRACT
Abbreviations ................................................................................................................................. 747 I. Introduction .......................................................................................................................... 748 II. Lipid Composition of the Brain ............................................................................................ 748 III. Metabolic Considerations ..................................................................................................... 754 IV. Dietary Effects and Recommendations ................................................................................ 754 V. Effects of PUFAs on Cognitive Function ............................................................................. 756
A. Cholesterol and Sphingolipids ...................................................................................... 757 B. Docosahexaenoic Acid in the Brain ............................................................................. 757 C. Plasmalogens ................................................................................................................ 758
VI. Use of Animal Models for the Study of Lipids in Alzheimer’s Disease .............................. 759 VII. Conclusions ........................................................................................................................... 760 References ...................................................................................................................................... 761
Next to adipose tissue, the brain is the most lipid-rich organ. Much of this is due to typical membrane lipids-phosphoglycerides, sphingolipids, and cholesterol (Table 29.1). Most of these molecules are commonly found in other tissues [1-3]. However, certain features in the brain are characteristic. For example, this tissue has a high concentration of ether lipids (e.g., ethanolamine plasmalogens) and polyunsaturated fatty acids (PUFAs) (especially arachidonate [ARA] and the n-3 PUFA docosahexaenoic acid [DHA]). In contrast, brain sphingolipids are enriched in saturated or monounsaturated fatty acids. There are also a number of unusual or “atypical” lipids in the brain; N-acylphospholipids [4] and certain glycosphingolipids [5] are examples. One aspect of the brain that bears emphasizing is its complexity, whereas, for example, the liver is predominantly one cell type-hepatocytes-the brain has many different cells of varying shapes and sizes. Even when particular brain areas are analyzed and studied, the results are often complicated by the various cells present. This should be borne in mind when attempting to interpret analytical data.
