title: Interaction of sesamin and eicosapentaenoic acid against delta 5 desaturation and n-6/n-3 ratio of essential fatty acids in rat.
abstract: Sesamin is a specific inhibitor of delta 5 desaturation, the conversion from dihomo-gamma-linolenic acid (20:3, n-6) to arachidonic acid (AA, 20:4, n-6). Previously, we reported that sesamin inhibited delta 5 desaturation of n-6 fatty acids in rat hepatocytes but not that of n-3 fatty acids, from 20:4 (n-3) to eicosapentaenoic acid (EPA, 20:5, n-3). In this study, we investigated the interaction of sesamin and EPA on delta 5 desaturation of both series and the n-6/n-3 fatty acids ratio by measuring actural fatty acid contents in vivo. Rats were fed three types of dietary oils; 1) linoleic acid (LA, 18:2, n-6): linolenic acid (LLA, 18:3, n-3) = 3:1, n-6/n-3 ratio of 3:1 (LA group), 2) LA:LLA = 1:3, n-6/n-3 ratio of 1:3 (LLA group), 3) LA:LLA:EPA = 1:0.5:3, n-6/n-3 ratio of 1:3.5 (EPA group) with or without sesamin (0.5% w/w) for 4 weeks. In all groups, sesamin administration increased the content of dihomo-gamma-linolenic acid (20:3, n-6) in the liver and decreased the delta 5 desaturation index of n-6 fatty acid, the ratio of 20:4/20:3 (n-6). On the contrary, the delta 5 desaturation index of n-3 fatty acid, the ratio of 20:5 + 22:5 + 22:6/20:4 (n-3), was increased by the administration of sesamin. These results suggest that sesamin inhibits the delta 5 desaturation of n-6 fatty acid, but not that of n-3 fatty acid in rat livers. Sesamin administration decreased incorporation of EPA (n-3) and simultaneously increased the AA (n-6) content in the liver. The n-6/n-3 ratio in the liver was increased by administering sesamin under n-3 rich conditions, i.e., the LLA and EPA groups.
authors.affiliation: Institute of Environmental Science for Human Life, Ochanomizu University, Tokyo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Umeda-Sawada
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
authors.forename: O
authors.initials: O
authors.lastname: Igarashi
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004149:Dioxoles / Q000494:pharmacology*; D004347:Drug Interactions; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D017705:Lignans; D008055:Lipids / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010713:Phosphatidylcholines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
chemical_list: D000924:Anticholesteremic Agents; D004149:Dioxoles; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D017705:Lignans; D008055:Lipids; D010713:Phosphatidylcholines; D015118:Eicosapentaenoic Acid; C054125:sesamin