Metabolism of hexacosatetraenoic acid (C26:4,n-6) in immature rat brain.
Rat brain was recently found to contain polyenoic very-long-chain fatty acids (VLCFA) belonging to the n-3 and n-6 series with four, five and six double bonds and even-carbon chain lengths from 24 to 38 [Robinson, Johnson & Poulos (1990) Biochem. J. 265, 763-767]. In the present paper, the metabolism in vivo of hexacosatetraenoic acid (C26:4,n-6) was studied in neonatal rat brain. Rats were injected intracerebrally with [1-14C]C26:4,n-6 and the labelled metabolites were examined after 4 h. Radioactivity was detected mainly in non-esterified fatty acids, with smaller amounts in other neutral lipids and phospholipids. Radiolabelled fatty acid products included C28-36 tetraenoic and C26-28 pentaenoic VLCFA formed by elongation and desaturation of the substrate, and C14-24 saturated, C16-24 monoenoic, C18-24 dienoic, C18-22 trienoic and C20-24 tetraenoic fatty acids formed from released [1-14C]acetate either by synthesis de novo or by elongation of endogenous fatty acids. The data suggest that polyenoic VLCFA are synthesized in brain from shorter-chain precursor fatty acids and undergo beta-oxidation.
Department of Chemical Pathology, Adelaide Medical Centre for Women and Children, South Australia.
B S
BS
Robinson
D W
DW
Johnson
A
A
Poulos
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D010743:Phospholipids / Q000096:biosynthesis; D011865:Radioisotope Dilution Technique; D051381:Rats; D011919:Rats, Inbred Strains
D002250:Carbon Radioisotopes; D005231:Fatty Acids, Unsaturated; D008055:Lipids; D010743:Phospholipids; C063979:hexacosatetraenoic acid