n-3 불포화지방산의 중추신경계에서의 중요성에 관한 고찰

A Study of the Importance of n-3 Polyunsaturated Fatty Acids on the Central Nervous System

  The nervous system is the organ with the second greatest concentration of lipids, immediately after adipose tissue. These lipids are practically all structural and participate directly in the functioning of cerebral membranes. The phospholipids of excitable membranes of the central nervous system are unusual in that there is a prevalence of the polyunsaturated fatty acyl chain docosahexaenoic acid(DHA, 22 : 6 n-3). Membranes from nonneural tissues contain phospholipids with much lower amounts of this fatty acyl chain.   High levels of DHA in the cerebral cortex and the retina suggest that n-3 fatty acids may be indispensable for neural development in newborns. The requirement for DHA is very large during the development and differentiation of the central nervous system. This coincides with synaptogenesis and with the biogenesis of photoreceptor membranes. Depletion of DHA early in life has been associated with loss of visual acuity in infants of nonhuman primates and abnormalities of learning performance in rats. This nutritional deficiency eventually causes visual disturbances and alterations in the electroretinogram.   There are two basic processes involved in maintaining high levels of DHA in the central nervous system. First, there is a signaling mechanism present in the central nervous system that tells the liver to send DHA when it is needed. This signal or messenger may arrive through the systemic circulation. At that time, the liver secretes a DHA-containing lipoprotein into the blood. Second, a receptor-mediated recognition mechamism located in the central nervous system causes the sequestering of DHA-containing lipoproteins from the blood, and then uptake into cells. All organs are exposed to the circulating DHA, but the central nervous system takes up the majority of the DHA molecules.