Docosahexaenoic acid accumulation in the prenatal brain - Prooxidant and antioxidant features

Docosahexaenoic acid (DHA; 22:6 n-3) is the major polyunsaturated fatty aci d (FA) in the adult rat brain and it accumulates significantly more than an y other FA prior to birth. Under normal nutritional conditions, fetal-brain DHA accumulation is substantial, with a "DHA accretion spurt" being demons trated in the last period of gestation. Under stress conditions, this spurt may be harmful owing to an increase in multiple double-bond targets for li pid peroxidation. The "DHA accretion spurt" is supported by the maternal su pply of DHA or its precursor. Under maternal dietary n-3 FA deficiency, DHA content in the fetal brain can be restored by direct intraamniotic injecti on of mM concentrations of ethyl-DHA (Et-DHA). This approach may hold a pot ential advantage in the event of maternal-fetal insufficiency, a stress tha t may cause intrauterine growth retardation. It also revealed a potential b eneficial effect after in utero ischemic stress; brain slices from Et-DHA-t reated fetuses formed less oxidation products, as detected by thiobarbituri c acid (TBA), compared to controls. Furthermore, brain-lipid extracts from Et-DHA but not ethyl-oleate treated fetuses, exhibited hydroxyl radical sca venging activity, as demonstrated by electron spin-resonance technique. Par t of the beneficial effect of Et-DHA administration on the fetal brain may be attributed to enhanced free-radical scavenging capability, a phenomenon not directly related to vitamin E or lipid-soluble antioxidant levels.