Seasonal variation in some of the lipid components of sprats (Sprattus sprattus)

Dietary supplementation with long-chain monounsaturated fatty acids attenuates obesity-related metabolic dysfunction and increases expression of PPAR gamma in adipose tissue in type 2 diabetic KK-Ay mice

The objective of present study was to examine the effect of long-chain monounsaturated fatty acids (LC-MUFAs) with chain lengths longer than 18 (i.e., C20:1 and C22:1 isomers combined) on obesity-related metabolic dysfunction and its molecular mechanisms. Type-2 diabetic KK-Ay mice (n = 20) were randomly assigned to the 7% soybean oil-diet group (control group) and 4% LC-MUFA concentrate-supplemented-diet group (LC-MUFA group). At 8 weeks on the diet, the results showed that plasma, liver and adipose tissue levels of C20:1 and C22:1 isomers increased significantly with LC-MUFA treatment. Supplementation with LC-MUFAs markedly reduced white fat pad weight as well as adipocyte size in the mice. The levels of plasma free fatty acids, insulin, and leptin concentration in the obese diabetic mice of the LC-MUFA group were also decreased as compared with the mice in the soybean oil-diet control group. Dietary LC-MUFAs significantly increased the mRNA expression of peroxisome proliferator-activated receptor gamma (Pparg), lipoprotein lipase (Lpl), fatty acid transport protein (Fatp), fatty acid translocase/CD36 (Cd36), as well as mRNA expression of genes involved in lipid oxidation such as carnitine palmitoyltransferase-1A (Cpt1a) and citrate synthase (Cs), and decreased the mRNA expression of inflammatory marker serum amyloid A 3 (Saa3) in the adipose tissues of diabetic mice. The results suggest that LC-MUFAs may ameliorate obesity-related metabolic dysfunction partly through increased expression of Pparg as well as its target genes, and decreased inflammatory marker expression in white adipose tissue.

Beneficial effects of dietary fish-oil-derived monounsaturated fatty acids on metabolic syndrome risk factors and insulin resistance in mice

The aim of this study was to elucidate the effect of fish-oil-derived monounsaturated fatty acids (MUFAs) containing large amounts of C20:1 and C22:1 isomers on metabolic disorders in mice. Male C57BL/6J mice were fed a 32% lard diet (control) or a 27% lard plus 5% saury-oil-derived MUFA diet for 6 weeks. Dietary MUFA improved insulin resistance and alleviated metabolic syndrome risk factors by reducing blood glucose and lipids. These favorable changes may be attributed to an improved adipocytokine profile. MUFA ingestion resulted in favorable changes in mRNA expression of genes involved in glucose/lipid metabolism (SCD-1, CPT1a, UCPs, and CS) as well as inflammation (MAC1, MMP3, and SAA3) and alterations in fatty acid composition. Our data suggest that marine MUFA improved glucose/lipid homeostasis and hindered the development of metabolic syndrome in obese mice.

The high content of monoene fatty acids in the lipids of some midwater fishes: family Myctophidae

The total lipids of eleven species of Myctophids caught at depths between 20 and 700 m in the northern Pacific Ocean were analyzed using silicic acid column chromatography (lipid classes) and capillary gas chromatography (fatty acid and fatty alcohol composition). The major components in the lipid classes were triacylglycerols or wax esters; triacylglycerols were the dominant acyl neutral lipids (68.1-96.1%) in eight species, and wax esters were found as the dominant lipid (85.5-87.9%) in three species. The major fatty acids and alcohols contained in the wax esters of the three fishes were 18:1n-9, 20:1n-9, 20:1n-11, and 22:1n-11 for fatty acids, and 16:0, 18:1, 20:1 and 22:1 for fatty alcohols. Fatty acids in the triacylglycerols ranging from C14 to C22 were predominantly of even chain length. The major components were 16:0, 16:1n-7, 18:1n-9, 20:1n-11, 22:1n-11, 20:5n-3 (icosapentaenoic acid), and 22:6n-3 (docosahexaenoic acid). In both the triacylglycerols and the wax esters, the major fatty components were monoenoic acids and alcohols. It is suggested from the lipid chemistry of the Myctophids that they may prey on the same organisms as the certain pelagic fishes such as saury and herring, because the large quantities of monoenoic fatty acids are similar to those of saury, herring, and sprats whose lipids originate from their prey organisms such as zooplanktons which are rich in monoenoic wax esters.

Biochemical Implications of Seasonal Trends in the Iodine Values and Free Fatty Acid Levels of Commercially Produced Atlantic Coast Herring Oils

Annual surveys of commercial herring oils produced in summer and fall off southwestern Nova Scotia and in winter and spring off southwestern Newfoundland showed iodine values (IV) mostly within the range 135 to 105 in both locations for the years 1965–70. Two systematic trends in IV with season were detected. The first extended uniformly over the whole of each fishery season and was limited to no more than ± 5 IV units. It is believed to represent the influence of long-term average environmental conditions that may vary from year to year and that establish the basic fatty acid compositions of the fish entering the fishery. The second was observed as a seasonal decline, over 2–3 months, of 20 IV units in the Nova Scotia fishery, and of 10 IV units in the Newfoundland fishery. It is proposed that this short-term effect follows from an increase in the relative proportion of the low-density, long-chain, monoethylenic fatty acids characteristic of clupeid oils that could decrease residual fat density at a time of general fat depletion and corresponding density increase for the fish as a whole.Free fatty acids (FFA) in freshly produced oils were also examined. In both fisheries % FFA seldom exceeded 1 and under optimum conditions the % FFA were consistently about 0.2–0.3. Annual seasonal % FFA effects were apparently restricted to an increase in April in the Newfoundland fishery associated with high IV oils of a pink colour denoting heavy spring feeding.