linoleic-acid and sesamin

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

The effects of a combination of dietary conjugated linoleic acid (CLA) supplemented with sesamin on hepatic ketogenesis and triacylglycerol secretion were compared using the livers of rats fed diets containing 1% CLA or linoleic acid (LA) in combination with 0.2% sesamin for 14 d, respectively. The feeding of CLA, as compared to LA, caused a significant reduction in the weight of perirenal adipose tissue but not that of epididymal adipose tissue, and affected neither growth parameters nor hepatic lipid concentration. Hepatic production of ketone bodies was consistently higher in rats fed CLA than in those fed LA, while triacylglycerol secretion was reversed. No significant difference was noted in the hepatic secretion of cholesterol among the groups. Although there was no effect of the dietary combination of CLA with sesamin on adipose tissue weight, hepatic lipid parameters and ketone body production were observed: i.e., triacylglycerol secretion tended to be reduced. These results suggest that the dietary combination of CLA with sesamin may be an effective approach for lowering serum triacylglycerol levels. The decreased hepatic secretion of triacylglycerol is, in part, due to enhanced fatty acid oxidation in the liver.

Topics: Animals; Anticholesteremic Agents; Body Composition; Diet; Dioxoles; Ketone Bodies; Lignans; Linoleic Acid; Lipid Metabolism; Liver; Male; Perfusion; Rats; Rats, Sprague-Dawley; Time Factors; Triglycerides; Weight Gain

To estimate the relative significance of exogenous and endogenous fatty acid substrates in decreasing hepatic triacylglycerol secretion after sesamin feeding, livers from rats fed diets supplemented with and without sesamin (sesamin: episesamin, 1:1, w/w) were perfused in the presence and absence of an exogenous di-trans isomer of linoleic acid (linolelaidic acid, trans,trans-9,12-octadecadienoic acid). Both exogenous trans fatty acid and dietary sesamin, as compared with respective controls, resulted in a marked increase in hepatic ketogenesis; however, the beta-hydroxybutyrate to acetoacetate ratio was elevated by exogenous fatty acid and decreased by dietary sesamin. On the other hand, hepatic secretions of triacylglycerol, phospholipid and cholesterol were markedly lowered in rats fed sesamin, especially when exogenous fatty acid substrate was provided. The relative significance of the exogenous fatty acid was observed in the dietary sesamin-induced decrease in hepatic secretion of triacylglycerol. These results suggest that increased fatty acid oxidation by dietary sesamin, as reflected by enhanced ketone body production, leads to decreased partition of fatty acid substrates to the esterification pathways, and this in turn reduces the synthesis and secretion of triacylglycerol. The altered metabolism of exogenous fatty acids in the liver was therefore a major determinant for the synthesis and secretion of triacylglycerol.

Topics: Animals; Diet; Dioxoles; Fatty Acids; Hypolipidemic Agents; Ketone Bodies; Lignans; Linoleic Acid; Lipid Metabolism; Liver; Male; Rats; Rats, Wistar; Triglycerides

We examined the effect of three dietary fats, safflower oil (SAF) rich in linoleic acid, borage oil (BOR) rich in gamma-linolenic acid, and perilla oil (PER) rich in alpha-linolenic acid, on the lipid metabolism, and chemical mediator and immunoglobulin levels in Sprague-Dawley rats, as well as the dietary effect of sesame-derived antioxidative sesamin. The serum cholesterol, phospholipid, triglyceride, prostaglandin E2 level and splenic leukotriene B4 level were lower in the rats fed on BOR or PER than in those fed on SAF. SES feeding suppressed the expression of the lipid-decreasing effect of BOR, but not in the rats fed on PER. In respect of the fatty acid composition of the liver and spleen, PER feeding gave a lower arachidonic acid level, and higher eicosapentaenoic and docosahexaenoic acid levels than SAF feeding did, while the effect of BOR feeding was marginal. The effect of SES feeding on fatty acid composition was much smaller than that of dietary fats. In respect of immunoglobulin production, PER + SES feeding gave the lowest IgE productivity in the mesenteric lymph node lymphocytes. These results suggest that PER feeding regulated lipid metabolism and exerted an anti-allergic effect by a different mechanism from that with BOR feeding.

Topics: alpha-Linolenic Acid; Animals; Anticholesteremic Agents; Dietary Fats; Dioxoles; gamma-Linolenic Acid; Immunoglobulins; Lignans; Linoleic Acid; Lipids; Male; Plant Oils; Rats; Rats, Sprague-Dawley; Safflower Oil