8-11-14-eicosatrienoic-acid and sesamin

Interrelated effects of dihomo-γ-linolenic acid (DGLA) and arachidonic acid (ARA), and sesamin, a sesame lignan, on hepatic fatty acid synthesis and oxidation were examined in rats. Rats were fed experimental diets supplemented with 0 or 2 g/kg sesamin (1:1 mixture of sesamin and episesamin), containing 100 g/kg of maize oil or fungal oil rich in DGLA or ARA for 16 d. Among the groups fed sesamin-free diets, oils rich in DGLA or ARA, especially the latter, compared with maize oil strongly reduced the activity and mRNA levels of various lipogenic enzymes. Sesamin, irrespective of the type of fat, reduced the parameters of lipogenic enzymes except for malic enzyme. The type of dietary fat was rather irrelevant in affecting hepatic fatty acid oxidation among rats fed the sesamin-free diets. Sesamin increased the activities of enzymes involved in fatty acid oxidation in all groups of rats given different fats. The extent of the increase depended on the dietary fat type, and the values became much higher with a diet containing sesamin and oil rich in ARA in combination than with a diet containing lignan and maize oil. Analyses of mRNA levels revealed that the combination of sesamin and oil rich in ARA compared with the combination of lignan and maize oil markedly increased the gene expression of various peroxisomal fatty acid oxidation enzymes but not mitochondrial enzymes. The enhancement of sesamin action on hepatic fatty acid oxidation was also confirmed with oil rich in DGLA but to a lesser extent.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Cell Extracts; Corn Oil; Dioxoles; Fatty Acids; Fungi; Gene Expression Regulation, Enzymologic; Hypolipidemic Agents; Lignans; Lipids; Lipogenesis; Lipolysis; Liver; Male; Oxidation-Reduction; Peroxisomes; Rats; Rats, Sprague-Dawley; RNA, Messenger

In this study, we examined the effects of sesamin and vegetable oil on the concentrations of polyunsaturated fatty acid (PUFA) and lipids (triacylglycerol, free cholesterol, and phospholipid), and beta-oxidation enzyme activities in the rat liver. Rats were fed a diet containing 5% (low-fat diet) or 20% (high-fat diet) salad oil (rapeseed oil: soybean oil, 7:3) with or without sesamin (0.5% w/w) for 4 wk. As a result, the concentrations of linoleic acid (LA, n-6), alpha-linolenic acid (ALA, n-3), and total PUFA in the liver increased significantly as the result of the high-fat diet. In the high-fat diet groups, sesamin administration decreased the concentrations of LA, ALA, and total PUFA to almost the same level as the low-fat diet group, while it increased the concentrations of dihomo-gamma-linolenic acid (DGLA, n-6) and arachidonic acid (AA, n-6). The activities of carnitine acyltransferase and acyl-CoA dehydrogenase in liver mitochondria were enhanced by the intake of the high-fat diet, and were further enhanced by the administration of sesamin. Peroxisomal acyl-CoA oxidase activity was also enhanced by sesamin, while it was not affected by the dietary fat level. These results suggest that sesamin suppressed the increase of hepatic PUFA concentration caused by feeding the high-fat diet through enhancing the enzyme activities of fatty acid beta-oxidation and PUFA metabolism from LA and ALA.

Topics: 8,11,14-Eicosatrienoic Acid; Acyl-CoA Dehydrogenase; alpha-Linolenic Acid; Animals; Arachidonic Acid; Carnitine Acyltransferases; Dietary Fats; Dioxoles; Fatty Acids, Monounsaturated; Fatty Acids, Unsaturated; Lignans; Linoleic Acid; Liver; Male; Mitochondria, Liver; Plant Oils; Rapeseed Oil; Rats; Rats, Wistar; Soybean Oil

Sesamin, a lignan in sesame seeds and sesame seed oil, and capsaicin, the pungent principle of hot red pepper, affect lipid metabolism. Sesamin specifically inhibits delta5 desaturase activity in the Mortierella alpina fungus and rat liver microsomes, however, the effects of sesamin and capsaicin on mRNA expressions of delta6 and delta5 desaturases are not still clear. In this study, we investigated the effects of sesamin and capsaicin on the desaturation indexes of delta6 [(gamma-linolenic acid+dihomo-gamma-linolenic acid)/linolenic acid, (GLA+DGLA)/LA] and delta5 (arachidonic acid/DGLA, AA/DGLA) and mRNA expressions of delta6 and delta5 desaturases in rat primary cultured hepatocytes. To measure the mRNA expressions of delta6 and delta5 desaturase, hepatocytes were cultured in the presence of sesamin or capsaicin for 24 h. To investigate the delta6 or delta5 desaturation index, hepatocytes were cultured in the presence of LA or DGLA, respectively, with sesamin or capsaicin for 24 h. The fatty acid composition of the cells was measured by GLC. The mRNA expressions of delta6 and delta5 desaturases were detected by real time quantitative RT-PCR. Sesamin and capsaicin had no effect on the mRNA expressions of delta6 and delta5 desaturases in rat hepatocytes. Capsaicin had no effect on both delta6 and delta5 desaturation indexes, either. On the other hand, sesamin significantly reduced the index of delta5 desaturation but not delta6 desaturation. These results suggested that sesamin reduced the delta5 desaturation index without the changing of the delta5 desaturase mRNA level.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Capsaicin; Cells, Cultured; Delta-5 Fatty Acid Desaturase; Dioxoles; Fatty Acid Desaturases; Gene Expression; Hepatocytes; Lignans; Linoleic Acid; Linoleoyl-CoA Desaturase; Male; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger