Both maternal and offspring Elovl2 genotypes determine systemic DHA levels in perinatal mice.

The molecular details relevant to dietary supplementation of the omega-3 fatty acid DHA in mothers as well as in their offspring are not clear. The PUFA elongase, elongation of very long-chain fatty acid (ELOVL)2, is a critical enzyme in the formation of DHA in mammals. In order to address the question regarding the origin of DHA during perinatal life, we have used DHA-deficient Elovl2-ablated mice as a model system to analyze the maternal impact on the DHA level in their offspring of various genotypes. Elovl2-/- mothers maintained on control diet had significantly lower systemic levels of DHA compared with the Elovl2+/- and Elovl2+/+ mothers. Dietary DHA administration during the pregnancy and lactation periods led to increased DHA accretion in maternal tissues and serum of all genotypes. The proportion of DHA in the liver and serum of the Elovl2-/- offspring was significantly lower than in the Elovl2+/+ offspring. Remarkably, the DHA level in the Elovl2+/- offspring nursed by DHA-free-fed Elovl2-/- mothers was almost as high as in +/+ pups delivered by +/+ mothers, suggesting that endogenous synthesis in the offspring can compensate for maternal DHA deficiency. Maternal DHA supplementation had a strong impact on offspring hepatic gene expression, especially of the fatty acid transporter, Mfsd2a, suggesting a dynamic interplay between DHA synthesis and DHA uptake in the control of systemic levels in the offspring.

Stimulatory effect of sesamin on hepatic cytochrome P450 activities in Atlantic salmon (Salmo salar L.) is not directly associated with expression of genes related to xenobiotic metabolism.

1. This study examined hepatic cytochrome P450 (CYP450) response to dietary sesamin in combination with different n-6/n-3 fatty acid ratios in fish diet. Over a period of 4 months, fish were fed seven different experimental diets an n-6/n-3 FA ratio of either 0.5 or 1.0 in combination with two sesamin levels: low sesamin = 1.16 g/kg feed and high sesamin = 5.8 g/kg feed. Control diets did not contain sesamin. 2. The CYP450-associated activities of ethoxyresorufin O-deethylase (EROD), 7-benzyloxy-4-trifluoromethylcoumarin O-debenzylation (BFCOD), pentoxyresorufin O-depentylase (PROD), coumarin hydroxylase (COH), methoxyresorufin O-deethylase (MROD) and p-nitrophenol hydroxylase (PNPH) were significantly induced by dietary sesamin in a dose-related manner. 3. Expressions of the genes CYP1A1, CYP1A3, CYP3A, AhR1α, AhR2ß, AhR2δ and PXR involved in the regulation of CYP450 activities, was not the primary source of this induction.

Fatty acid composition of Swedish bakery products, with emphasis on trans-fatty acids.

Trans-fatty acids (TFA) have been associated with increased risk of coronary heart disease, by affecting blood lipids and inflammation factors. Current nutrition recommendations emphasise a limitation of dietary TFA intake. The aim of this study was to investigate fatty acid composition in sweet bakery products, with emphasis on TFA, on the Swedish market and compare fatty acid composition over time. Products were sampled in 2001, 2006 and 2007 and analysed for fatty acid composition by using GC. Mean TFA levels were 0.7% in 2007 and 5.9% in 2001 of total fatty acids. In 1995-97, mean TFA level was 14.3%. In 2007, 3 of 41 products had TFA levels above 2% of total fatty acids. TFA content had decreased in this product category, while the proportion of saturated (SFA) and polyunsaturated (PUFA) fatty acids had increased, mostly through increased levels of 16:0 and 18:2 n-6, respectively. The total fat content remained largely unchanged.

¹H NMR-based metabolomics studies on the effect of sesamin in Atlantic salmon (Salmo salar).

A (1)H NMR-based metabolomics approach was used to explore the impact of dietary sesamin on the liver and white muscle metabolic profile of Atlantic salmon (Salmo salar). Fish were fed diets containing different n-6/n-3 fatty acid ratios (V0.5 or V1) and sesamin contents [without (S0), low (SL) 1.16 g/kg feed, and high (SH) 5.8 g/kg feed] for 4 months. Liver and white muscle extracts of aqueous polar and chloroform lipid phases were collected. Multivariate data analyses (PCA and OPLS-DA) of liver chloroform phase showed that high levels of sesamin affected the metabolic profile impartially of the n-6/n-3 ratio. In the aqueous phase, the metabolome of liver and white muscle were affected in fish fed an n-6/n-3 ratio of 1.0 and 0.5, respectively. With high inclusion of sesamin, the levels of several metabolites (e.g. glucose, glycogen, leucine, valine, creatine, carnitine, lactate, nucleosides) were increased. These metabolites are mainly associated with energy metabolism, suggesting that high sesamin inclusion affects liver and white muscle metabolism in fish. This is consistent with lower body weights found in fish fed high sesamin content.

In vitro inhibition of 7-ethoxyresorufin-O-deethylase (EROD) and p-nitrophenol hydroxylase (PNPH) activities by sesamin in hepatic microsomes from two fish species.

In the present study, we investigated the effect of sesamin on CYP1A (7-ethoxyresorufin-O-deethylase, EROD) and CYP2E1-like activities (p-nitrophenol hydroxylase, PNPH) in hepatic microsomes obtained from Atlantic salmon (Salmo salar) and common carp (Cyprinus carpio). Addition of sesamin to the incubations in a concentration range from 1 to 200 µM decreased the activities of EROD and PNPH in a concentration dependent manner. It is likely that the inhibition of EROD was mechanism-based as demonstrated by the decrease in the IC50 value from 5.9 to 3.2 µM for A. salmon and from 7.9 to 3.0 µM for common carp when 5 min pre-incubation step was included. Similarly, PNPH activity was inhibited by sesamin with a decrease in the IC50 values from 61.7 to 15.2 µM for A. salmon and from 194.3 to 20.7 µM for common carp. Thus, our results indicated that sesamin can act as a mechanism-based inhibitor of EROD and PNPH activity with similar degree of inhibition in both fish species. More importantly, the inhibition of CYP1A, in addition to being mechanism-based, was competitive with K(i) value of 5.3 µM.

Fatty acids and gene expression responses to bioactive compounds in Atlantic salmon (Salmo salar L.) hepatocytes.

OBJECTIVES: Effects of bioactive compounds on expression of genes involved in lipid metabolism and fatty acid composition were investigated in Atlantic salmon (Salmo salar L.) primary hepatocytes. METHODS: Five treatments were investigated: I) genistein 0.005 mM, II) genistein 0.025 mM, III) lipoic acid 0.2 mM, IV) sesamin/episesamin 0.05 mM, V) sesamin 0.05 mM and compared to controls. The relative expression of genes involved in lipid homeostasis was analysed after 12h and 48h. RESULTS: Incubation with lipoic acid, sesamin and episesamin/sesamin for 48h had significant effect on all analysed genes involved in lipid uptake, ß-oxidation, elongation and desaturation, some effects were detected on the expression of peroxisome prolifertor-activated receptor (PPARs). Also effects on the fatty acid composition were found. CONCLUSION: The strongest effect of bioactive copounds on hepatocyte gene expression was detected after 48 hours.

Effect of processing on amine formation and the lipid profile of cod (Gadus morhua) roe.

The processing of fish roe leads to changes in its chemical composition, the extent of which depends on the techniques and additives employed. This study aimed to investigate the effects of ripening temperature and the use of sodium benzoate and citric acid on the quality of ripened cod roe, with respect to the contents of volatile base nitrogen (VBN), trimethylamine (TMA), biogenic amines (BA) and on the lipid composition. In comparison with fresh roes, ripened roes presented higher contents of VBN, TMA, BA and the proportion of free fatty acids regardless of the temperature and additives used during the ripening process. The greatest increases were observed in the samples ripened at 17°C without additives, in which histamine was detected at 8.8mg/100g. A low ripening temperature was the main factor responsible for minimising changes in the cod roe composition. The addition of sodium benzoate as a preservative or citric acid to decrease the pH value had a significant effect in maintaining the quality of the cod roes, mainly at high ripening temperature.

Sesamin increases alpha-linolenic acid conversion to docosahexaenoic acid in atlantic salmon (Salmo salar L.) hepatocytes: role of altered gene expression.

In vitro cultivated Atlantic salmon (Salmo salar L.), hepatocytes were incubated without or with a mixture of sesamin and episesamin in order to test for possible effects on lipid metabolism. Sesamin/episesamin exposure (0.05 mM, final concentration) led to increased elongation and desaturation of (14)C 18:3n-3 to docosahexaenoic acid ((14)C 22:6n-3, DHA, P < 0.01) and down regulated gene expression of Delta6 and Delta5 desaturases compared to control treatment. Sesamin/episesamin further increased the hepatocytes capacity for fatty acid beta-oxidation of (14)C 18:3n-3 (P < 0.01) to the (14)C acid soluble products, acetate, malate and oxaloacetate, in agreement with an increased gene expression of carnitine palmitoyltransferase I. Also the gene expression of cluster of differentiation 36 was upregulated and the expression of scavenger receptor type B, peroxisome proliferator-activated receptors alpha and gamma were downregulated. The amount of triacylglycerols secreted by the cells tended to be lower in the sesamin/episesamin incubated hepatocytes than the control cells. This study shows that sesamin has favourable effects on lipid metabolism leading to increased level of DHA, which may be of interest for aquaculture use.

Sesamin supplementation increases white muscle docosahexaenoic acid (DHA) levels in rainbow trout (Oncorhynchus mykiss) fed high alpha-linolenic acid (ALA) containing vegetable oil: metabolic actions.

The effects of including an equi-mixture of sesamin and episesamin in fish diets based on vegetable oils of different fatty acid composition were examined. Sesamin/episesamin (hereafter named sesamin) was included at 0.58 g/100 g diet. The oil used in the feed was either a mixture of linseed and sunflower oils (6:4, by vol) or 100% linseed oil. Addition of sesamin increased the percentages of docosahexaenoic acid (DHA) in white muscle phospholipid and triacylglycerol fraction by up to 37% but the fatty acids in red muscle and liver were not affected. The expression of the peroxisome proliferator-activated receptor PPARalpha was significantly down regulated in the liver of the fish fed sesamin and mixed oil diet (P < 0.05). Sesamin and episesamin were detected in liver and muscle tissues of the fish that had been fed sesamin. Fish fed sesamin had elevated levels of total cytochrome P450 (CYP) enzymes and EROD activity in the liver, indicating an induction of CYP1A in this tissue. Our conclusion was that supplementation of fish feed with sesamin increased the proportions of DHA in the white muscle.