Roles of Unsaturated Fatty Acids (Especially omega-3 Fatty Acids) in the Brain at Various Ages and During Ageing

摘要: Among various organs, in the brain, fatty acids most extensively studied are omega-3 acids. Alpha-linolenic acid (18:3omega3) deficiency alters structure and function of membranes induces minor cerebral dysfunctions, as demonstrated animal models subsequently human infants. Even though brain is materially an organ like any other, that to say elaborated from substances present diet (sometimes exclusively), for long it was not accepted food can have influence on structure, thus its function. Lipids, especially acids, provided first coherent experimental demonstration effect (nutrients) brain. In fact after adipose tissue, richest lipids, whose only role participate membrane structure. First shown differentiation functioning cultured cells requires alpha-linolenic (the major component omega-3, omega3 family), but also very omega-6 carbon chains (1). It then course development, perturbs composition physicochemical properties cell membranes, neurones, oligodendrocytes, astrocytes (2). This leads modifications, biochemical physiological perturbations, results neurosensory behavioural upset (3). Consequently, nature polyunsaturated (in particular omega-3) formula milks infants (premature term) conditions visual abilities, including intellectual. Moreover, dietary certainly involved prevention some aspects cardiovascular disease (including at level vascularization), neuropsychiatric disorders, particularly depression, well dementia, notably Alzheimer's disease. Recent more marked abnormalities certain structures than others, frontal cortex pituitary gland severely affected. These selective lesions accompanied by disorders affecting tests (habituation, adaptation new situations). Biochemical partially reversed a phospholipid supplement, omega-3-rich egg yolk extracts or pig A dose-effect study showed phospholipids effective plant reverse consequences deficiency, partly because they provide preformed chains. decreases perception pleasure, slightly altering efficacy sensory organs structures. Age-related impairment hearing, vision smell due both decreased parts concerned receptors, inner ear retina. For example, given sweet taste larger quantity sugar subjects with deficiency. view occidental eating habits, has never been observed, impact studied. contrast, omega-9 specifically oleic reduction this many tissues, except (but sciatic nerve affected). therefore synthesized sufficient quantities, least during pregnancy-lactation, implying need intake. must be remembered organization neurons almost complete several weeks before birth, these remain subject's life time. disturbance neurons, alteration their connections, impaired turnover constituents stage life, will tend accelerate ageing. The enzymatic activities sytivities synthesis long-chain linoleic limited brain: depends exogenous supply. essential arachidonic cervonic acid, derived diet, unless liver acid. age-related hepatic desaturase (which chains, together elongases) impair membranes. structures, cortex, observed ageing, predominantly associated phosphatidylethanolamines (mainly form plasmalogens). Peroxisomal oxidation participating which less effectively protected against peroxidation free radicals.