Membrane docosahexaenoate is supplied to the developing brain and retina by the liver.
Docosahexaenoic acid [22:6 omega 3; 22:6(4, 7, 10, 13, 16, 19)] is concentrated in phospholipids of cellular membranes from brain and retina. Although linolenic acid [18:3 omega 3; 18:3(9, 12, 15)] is the major omega 3 fatty acid of mouse dams' milk, 22:6 is the prevalent omega 3 fatty acid in serum and tissues. Intraperitoneal injection of [1-14C]18:3 into 3-day-old mouse pups resulted in liver and serum lipid labeling that was initially high, followed by a rapid decline. In contrast, labeling of brain and retinal lipids were initially low and increased with time. Labeled 22:6 first appeared in liver 2 hr after injection and later in brain and retina. We suggest that 22:6 synthesized from 18:3 by the liver is secreted into the bloodstream in lipoproteins, taken up by brain and retina, and incorporated into cell membranes. We hypothesize that the 22:6 requirements of membranes (e.g., during synaptogenesis, photoreceptor membrane biogenesis, or repair after ischemic injury or neurodegenerative disorders) are met by a signal that is sent by the appropriate tissues to the liver to evoke the secretion of 22:6-containing lipoproteins.
Scott
B L
BL
Louisiana State University School of Medicine, Louisiana State University Eye Center, New Orleans 70112.
Bazan
N G
NG
D000818:Animals; D000833:Animals, Suckling / Q000378:metabolism; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D051379:Mice; D012160:Retina / Q000378:metabolism*; D013997:Time Factors
D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids