Fonctions biologiques des acides gras polyinsaturés dans les membranes nerveuses : une évolution des concepts

Abstract

Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) are the major polyunsaturated fatty acids in the membranes of brain and retinal cells. Animals specifically deficient in dietary n-3 fatty acids have reduced visual acuity and impaired learning ability. Studies on human infants have shown that adding DHA and AA to milk replacer-formulas can bring their concentrations in the infant blood lipids to values as high as those produced by breast feeding. The concurrent structural impact on the CNS membranes could have transient but significant outcomes on mental development and on maturation of visual function. In older subjects, neuropsychological and neurodegenerative diseases have been associated to impaired status of blood DHA and/or AA which might lead to decreased contents in neuronal membranes. The mechanisms by which polyunsaturated fatty acids can impact on neuronal functions involve the modulation of membrane biophysical properties, the regulation of neurotransmitter release, the synthesis of oxygenated biologically-active derivatives, and the nuclear receptor-mediated transcription of lipid-responsive genes.