|The lipid-rich nature of the brain has been recognized for a long time and it is
thought that the presence of myelin in the brain accounts for most of the lipid.
However, brain grey matter is also rich in lipid (mostly glycerophospholipids) by
comparison with other tissues (Svennerholm, 1968).
The polyunsaturated fatty acids (PUFA) associated with tissue
glycerophospholipids are derived from both the linoleic and linolenic acid series.
There is a tissue and species variation in the types of PUFA and in the ratio of
total 06:total 03 fatty acids (FA) in glycerophospholipids. This generalization
appears to be valid for all tissues except the grey matter of the brain where, in a
wide variety of different mammals, only three major PUFA occur: these are
20:406, 22:406 and 22:603 (Table I). Even in marine mammals, where the ratio,
dietary 06:03 FA may be as low as 0.1, there is a similar profile in the brain
PUFA (Bernhard, Lesch & Neuhaus-Meier, 1969; Leech, 1969). Another feature of
the brain lipids is the low level of linoleic acid compared with the levels in tissues
such as liver and muscle.
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