title: Fifteen weeks of dietary n-3 polyunsaturated fatty acid deprivation increase turnover of n-6 docosapentaenoic acid in rat-brain phospholipids.
abstract: Docosapentaenoic acid (DPAn-6, 22:5n-6) is an n-6 polyunsaturated fatty acid (PUFA) whose brain concentration can be increased in rodents by dietary n-3 PUFA deficiency, which may contribute to their behavioral dysfunction. We used our in vivo intravenous infusion method to see if brain DPAn-6 turnover and metabolism also were altered with deprivation. We studied male rats that had been fed for 15 weeks post-weaning an n-3 PUFA adequate diet containing 4.6% alpha-linolenic acid (α-LNA, 18:3n-3) or a deficient diet (0.2% α-LNA), each lacking docosahexaenoic acid (22:6n-3) and arachidonic acid (AA, 20:4n-6). [1-(14)C]DPAn-6 was infused intravenously for 5min in unanesthetized rats, after which the brain underwent high-energy microwaving, and then was analyzed. The n-3 PUFA deficient compared with adequate diet increased DPAn-6 and decreased DHA concentrations in plasma and brain, while minimally changing brain AA concentration. Incorporation rates of unesterified DPAn-6 from plasma into individual brain phospholipids were increased 5.2-7.7 fold, while turnover rates were increased 2.1-4.7 fold. The observations suggest that increased metabolism and brain concentrations of DPAn-6 and its metabolites, together with a reduced brain DHA concentration, contribute to behavioral and functional abnormalities reported with dietary n-3 PUFA deprivation in rodents. (196 words).
authors.affiliation: National Institute on Aging, National Institutes of Health, Bethesda, MD, USA. miki.i@uci.edu
authors.forename: Miki
authors.initials: M
authors.lastname: Igarashi
authors.forename: Hyung-Wook
authors.initials: HW
authors.lastname: Kim
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Lisa
authors.initials: L
authors.lastname: Chang
authors.forename: Kaizong
authors.initials: K
authors.lastname: Ma
authors.forename: Stanley I
authors.initials: SI
authors.lastname: Rapoport
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008297:Male; D010743:Phospholipids / Q000276:immunology*; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors
chemical_list: D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids; C026219:docosapentaenoic acid