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PubMedDate not supplied

Cataract development in diabetic sand rats treated with alpha-lipoic acid and its gamma-linolenic acid conjugate.

BACKGROUND: Diabetes commonly leads to long-term complications such as cataract. This study investigated the effects of alpha-lipoic acid (LPA) and its gamma-linolenic acid (GLA) conjugate on cataract development in diabetic sand rats. METHODS: Two separate experiments were conducted. In Experiment 1, sand rats were fed a "high-energy" diet (70% starch), an acute model of Type 2 diabetes, and injected with LPA. In Experiment 2, the animals received a "medium-energy" diet (59% starch), a chronic diabetic model, and were intubated with LPA or its GLA conjugate. Throughout the experiments, blood glucose levels and cataract development were measured. At the termination of the experiments, lens aldose reductase (AR) activity and lenticular reduced glutathione (GSH) levels were analyzed. RESULTS: LPA injection significantly inhibited cataract development and reduced blood glucose levels in rats fed the "high-energy" diet. Lens AR activity tended to be lower, while lenticular GSH levels increased. In sand rats fed a "medium-energy" diet (59% starch), LPA intubation had no effect on blood glucose levels and cataract development but GSH levels were increased. In contrast, sand rats intubated with GLA conjugate showed the highest blood glucose levels and accelerated cataract development. The conjugate treatment also decreased lenticular GSH content. CONCLUSIONS: The hypoglycemic effects of LPA are beneficial in the prevention of acute symptoms of Type 2 diabetes. It remains to be shown that the antioxidant activity of LPA is responsible for prevention or inhibition of cataract progression in sand rats.

Aldehyde Reductase↗
PubMed1986

Retinal function in rats and guinea-pigs reared on diets low in essential fatty acids and supplemented with linoleic or linolenic acids.

Rats were reared into a third generation on diets deficient in essential fatty acids supplemented with linoleic acid (18:2 n-6) or linolenic acid (18:3 n-3) with the object of depleting the retina of n-6 or n-3 fatty acids. In the rats fed 18:2 n-6 the percentage by weight of 22:6 n-3 in retinal fatty acids fell from 22.5 to 8.5% in first-generation animals but then remained unchanged in second and third generations. There was no difference in b-wave amplitudes of the electroretinogram between the rats fed 18:2 n-6 and those fed 18:3 n-3. In guinea-pigs fed purified diets low in 18:3 n-3 the percentage by weight of 22:6 n-3 in retinas fell from 8 to less than 0.5% by the third generation. However, there were no statistical differences in the b-wave amplitudes between these animals and those reared on a commercial diet. It is concluded that if n-3 fatty acids are involved in retinal function their role is too subtle to be detected by standard electroretinographic techniques.

Aging↗
PubMed2004

Docosahexaenoic acid and eicosapentaenoic acid, but not alpha-linolenic acid, suppress deoxynivalenol-induced experimental IgA nephropathy in mice.

Diets enriched in the (n-3) PUFAs, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and their precursor alpha-linolenic acid (ALA), were evaluated for efficacy in ameliorating the development of IgA nephropathy (IgAN) induced in mice by the mycotoxin deoxynivalenol (DON). The effects of DON were compared in mice that were fed for 18 wk with AIN-93G diets containing 1) 10 g/kg corn oil plus 60 g/kg oleic acid (control); 2) 10 g/kg corn oil plus 35 g/kg oleic acid and 25 g/kg DHA-enriched fish oil (DHA); 3) 10 g/kg corn oil plus 33 g/kg oleic acid and 27 g/kg EPA-enriched fish oil (EPA); and 4) 10 g/kg corn oil plus 37 g/kg oleic acid and 23 g/kg DHA + EPA (1:1) enriched fish oil (DHA + EPA). The DHA, EPA and DHA + EPA diets attenuated induction by dietary DON (10 mg/kg) of serum IgA and IgA immune complexes, kidney mesangial IgA deposition, and ex vivo IgA secretion by spleen cells. Consumption of the DHA + EPA diet for 8 wk significantly abrogated the DON-induced gene expression of interleukin (IL)-6, a requisite cytokine for DON-induced IgA nephropathy, in spleen and Peyer's patches. Finally, incorporation of ALA-containing flaxseed oil up to 60 g/kg in the AIN-93G diet did not affect DON-induced IgA dysregulation in mice. Taken together, both DHA and EPA, but not ALA, ameliorated the early stages of IgAN, and these effects might be related to a reduced capacity for IL-6 production.

Animals↗
PubMed1986

Dietary linolenic acid in man--an overview.

Small amounts of linolenic acid are ubiquitous in human food but only a few foodstuffs contain sizable amounts, namely some plant oils, butter and fish; in marine fish, linolenic acid is accomplished by eicosapaentaenoic acid, highly exceeding linolenic acid in quantity. Of the linolenic acid ingested, some is incorporated into phospholipids and cholesteryl esters, very little is elongated and eventually converted to prostaglandins; probably most linolenic acid is used as fuel. Polyunsaturated fatty acids of the (n-3)-series should no longer be considered to be similar with respect to their metabolic fate and their effects. In particular, results from experiments with "eskimo diets" may not be applied to considerations of linolenic acid. There may be a small dietary requirement for linolenic acid, possibly only for growing children; yet it is prudent to recommend diets which are not devoid of linolenic acid, especially in formula diets or parenteral nutrition. Some experiments suggest that high doses of linolenic acid exert untoward effects by inhibiting prostaglandin synthesis of the 1- and 2-series. The ratio between linoleic and linolenic acid in relevant experiments was such that only excessive use of linseed oil could produce them under conventional dietary conditions. Still it must be considered prudent to keep the linolenic acid content of foods well below that of linoleic acid.

Dietary Fats, Unsaturated↗
PubMed2001

Method to produce 9(S)-hydroperoxides of linoleic and linolenic acids by maize lipoxygenase.

Seed from maize (corn) Zea mays provides a ready source of 9-lipoxygenase that oxidizes linoleic acid and linolenic acid into 9(S)-hydroperoxy-10(E),12(Z)-octadecadienoic acid and 9(S)-hydroperoxy-10(E),12(Z),15(Z)-octadecatrienoic acid, respectively. Corn seed has a very active hydroperoxide-decomposing enzyme, allene oxide synthase (AOS), which must be removed prior to oxidizing the fatty acid. A simple pH 4.5 treatment followed by centrifugation removes most of the AOS activity. Subsequent purification by ammonium sulfate fractional precipitation results in negligible improvement in 9-hydroperoxide formation. This facile alternative method of preparing 9-hydroperoxides has advantages over other commonly used plant lipoxygenases.

Chromatography, High Pressure Liquid↗
PubMed2000

New cyclopentenone fatty acids formed from linoleic and linolenic acids in potato.

[1-14C]Linoleic acid was incubated with a whole homogenate preparation from potato stolons. The reaction product contained four major labeled compounds, i.e., the alpha-ketol 9-hydroxy-10-oxo-12(Z)-octadecenoic acid (59%), the epoxy alcohol 10(S),11(S)-epoxy-9(S)-hydroxy-12(Z)-octadecenoic acid (19%), the divinyl ether colneleic acid (3%), and a new cyclopentenone (13%). The structure of the last-mentioned compound was determined by chemical and spectral methods to be 2-oxo-5-pentyl-3-cyclopentene-1-octanoic acid (trivial name, 10-oxo-11-phytoenoic acid). Steric analysis demonstrated that the relative configuration of the two side chains attached to the five-membered ring was cis, and that the compound was a racemate comprising equal parts of the 9(R),13(R) and 9(S),13(S) enantiomers. Experiments in which specific trapping products of the two intermediates 9(S)-hydroperoxy-10(E),12(Z)-octadecadienoic acid and 9(S),10-epoxy-10,12(Z)-octadecadienoic acid were isolated and characterized demonstrated the presence of 9-lipoxygenase and allene oxide synthase activities in the tissue preparation used. The allene oxide generated from linoleic acid by action of these enzymes was further converted into the cyclopentenone and alpha-ketol products by cyclization and hydrolysis, respectively. Incubation of [1-14C]linolenic acid with the preparation of potato stolons afforded 2-oxo-5-[2'(Z)-pentenyl]-3-cyclopentene-1-octanoic acid (trivial name, 10-oxo-11,15(Z)-phytodienoic acid), i.e., an isomer of the jasmonate precursor 12-oxo-10,15(Z)-phytodienoic acid. Quantitative determination of 10-oxo-11-phytoenoic acid in linoleic acid-supplied homogenates of different parts of the potato plant showed high levels in roots and stolons, lower levels in developing tubers, and no detectable levels in leaves.

Carbon Radioisotopes↗
PubMed1991

Dietary alpha-linolenic acid is as effective as oleic acid and linoleic acid in lowering blood cholesterol in normolipidemic men.

The effect of dietary oleic acid (OA), linoleic acid (LA), and linolenic acid (LNA) on plasma lipid metabolism was studied in eight normolipidemic men. A mixed-fat diet composed of conventional foods was fed during 6-d pre- and post-experimental periods. The same basic diet but with 75% of the fat (26% of total energy) provided by sunflower and olive; canola; soybean; and sunflower, olive, and flax oils was fed during four 18-d experimental periods. Mean plasma total cholesterol (-18%), low-density-lipoprotein-cholesterol, (-22%) and very-low-density-lipoprotein-cholesterol (-41%) concentrations were significantly (P less than 0.004) lower after the experimental diets than after the mixed-fat diet. Mean serum apolipoprotein B (-19%) and apolipoprotein A-I (-9%) concentrations were also significantly (P less than 0.0007) lower after the experimental diets. The experimental diets were equally effective in lowering total and lipoprotein cholesterol and apolipoprotein concentrations in plasma, indicating that dietary OA, LA, and LNA were equally hypocholesterolemic.

Adult↗
PubMed2005

Gamma-Linolenic acid regulates the expression and secretion of SPARC in human cancer cells.

SPARC (secreted protein acidic and rich in cystein), also known as osteonectin and BM40, is a secreted glycoprotein. It confers matrix adhesion of cells including cancer cells, thus promoting cell migration. SPARC has been shown to be involved in the aggressive nature of cancer. The current study investigated the role of a n-6 polyunsaturated fatty acid, gamma linolenic acid (GLA) on the expression and secretion of SPARC from cancer cells. Human breast cancer cell line MCF-7 and MDA-MB-231, human colon cancer cells HT115 and HRT-18 were used in the study. Cancer cells were treated with GLA or other fatty acids over a range of concentrations. Presence of SPARC in the supernatant and in the cell lysate were analysed using Western blotting. Cellular SPARC was also assessed using immunocytochemistry. SPARC transcript in these cells were studied using RT-PCR. Cell-matrix adhesion was determined using a cell-matrix adhesion assay and cell migration analysis. Treatment of MDA-MB-231 and HT115 cells with GLA, at non-toxic levels, resulted in reduction of SPARC in supernatant as well as in the cell lysate. In contrast, there were little changes in the supernatant SPARC in MCF-7 and in HRT-18 cells. Cellular SPARC, as revealed by immunocytochemistry, also demonstrated a similar trend of changes as seen with protein blotting. Analysis of the SPARC transcript using RT-PCR has shown an up-regulation of SPARC mRNA by the fatty acid. GLA reduced cell-matrix adhesion in these cancer cells. It is concluded that GLA is a regulator of SPARC secretion and expression in cancer cells. It reduces the secretion of SPARC into surrounding environment, which may contribute to the reduction of cancer cells adhesion to the extracellular matrix and cell motility.

Cell Line, Tumor↗
PubMed1987

Alpha-linolenic acid deficiency in man: effect of essential fatty acids on fatty acid composition.

Alpha-linolenic acid deficiency (ALAD) is described in five adults receiving long-term gastric tube feeding with a commercially available powdered formula mixed with water and/or skimmed milk. Three patients receiving the same powder mixed with whole milk showed no signs of essential fatty acid deficiency (EFAD). The patients showed scaly dermatitis and skin atrophy. In four patients, supplementing with cod liver oil and soya oil for 4 weeks normalized n-3 acids in plasma and red cells, while n-6 acids remained unchanged or decreased slightly. At the same time, skin changes were normalized. In the fifth patient, supplementing with ethyl linolenate started to normalize skin changes within 5 days, and after 2 weeks had increased the red cell concentration of 22:6n-3 threefold. Simultaneously, 20:4n-6 increased twofold, to above control level. Minimal daily requirement of alpha-linolenic acid and of long-chain n-3 acids is estimated to be 0.2% to 0.4% and 0.1% to 0.2% of calories, respectively.

Adult↗
PubMed2003

[Alpha-linolenic acid and cardiovascular diseases].

IMPORTANCE AND METABOLISM OF ALPHA-LINOLENIC ACID: Alpha-linolenic acid is an essential fatty acid which cannot be produced in the body and must be taken by food. Both in animals and humans, alpha-linolenic acid is desaturated and elongated into eicosapentaenoic and docosahexaenoic acid. It is also incorporated into plasma and tissue lipids and its conversion is affected by levels of linoleic acid. POTENTIAL ROLE IN PATHOGENESIS OF CARDIOVASCULAR DISEASES: Diet enriched in n-3 fatty acids, especially alpha-linolenic acid, reduces the incidence of cardiac death. Studies have shown that alpha linolenic acid prevents ventricular fibrillation which is the main cause of cardiac death. Studies in rats suggest that alpha-linolenic acid may be more effective in preventing ventricular fibrillations than eicosapentaenoic and docosahexaenoic acid. Furthermore, alpha-linolenic acid is the main fatty acid decreasing platalet aggregation which is an important step in thrombosis i.e. non-fatal myocardial infarction and stroke. DIETARY SOURCES AND NUTRITION RECOMMENDATIONS: Dietary sources include flaxseed and flaxseed oil, canola oil, soybean and soybean oil, pumpkin seed and pumpkin oil, walnuts and walnut oil. Strong evidence supports beneficial effects of alpha-linolenic acid and its dietary sources should be incorporated into balanced diet for prevention of cardiovascular diseases. The recommended daily intake is 2 g with a ratio of 5/1 for linoleic/alpha-linolenic acid.

Animals↗
PubMed1976

Transformation of arachidonic acid and homo-gamma-linolenic acid by rabbit polymorphonuclear leukocytes. Monohydroxy acids from novel lipoxygenases.

Addition of arachidonic acid and homo-gamma-linolenic acid to a suspension of rabbit peritoneal neutrophils led to the synthesis of 5-L-hydroxy-6,8,11,14-eicosatetraenoic acid and 8-L-hydroxy-9,11,14-eicosatrienoic acid, respectively. Both hydroxy acids were found to be the main metabolites of their respective unsaturated C-20 fatty acid precursor, constituting more than 50% of the total substrate conversion. The formation of the two metabolites was not inhibted bb indomethacin, indicating that the enzymes involved were unrelated to the prostaglandin synthetase system. The presence in the two compounds of a hydroxyl group alpha to a pair of conjugated cis/trans double bonds suggested that they were formed by action of lipoxygenease(s).

8,11,14-Eicosatrienoic Acid↗
PubMed2007

The influence of dietary linoleic and alpha-linolenic acid on body composition and the activities of key enzymes of hepatic lipogenesis and fatty acid oxidation in mice.

We have recently suggested that feeding the C18 polyunsaturated fatty acid, alpha-linolenic acid (ALA), instead of linoleic acid (LA) reduced body fat in mice. However, the difference in body fat did not reach statistical significance, which prompted us to carry out this study using more animals and diets with higher contents of ALA and LA so that the contrast would be greater. The diets contained either 12% (w/w) LA and 3% ALA or 12% ALA and 4% LA. A low-fat diet was used as control. The diets were fed for 35 days. The proportion of body fat was not influenced by the type of dietary fatty acid. Plasma total cholesterol and phospholipids were significantly lower in ALA-fed mice than in mice fed LA. Activities of enzymes in the fatty acid oxidation pathway were significantly raised by these two diets when compared with the control diet. alpha-Linolenic acid vs. LA did not affect fatty acid oxidation enzymes. In mice fed the diet with LA activities of enzymes of de novo fatty acid synthesis were significantly decreased when compared with mice fed the control diet. alpha-Linolenic acid vs. LA feeding did not influence lipogenic enzymes. It is concluded that feeding mice for 35 days with diets either rich in LA or ALA did not significantly influence body composition.

Animals↗
PubMed2003

Biomimesis of linolenic acid transport through model lipidic membranes by differential scanning calorimetry.

Multienoic fatty acids, such as linolenic acid, show their ability to interact with and to penetrate into model biomembranes by biomimetic experiments performed to support the absorption route followed by n-3 fatty acid in cells. The thermotropic behavior of model biomembranes, that is, dimyristoylphosphatidylcholine multilamellar or unilamellar vesicles, interacting with linolenic acid was investigated by differential scanning calorimetry. When dispersed in liposomes during their preparation, the examined biomolecule was found to interact with the phospholipid bilayers by modifying the gel to liquid-crystal phase transition of lipid vesicles; this modification is a function of the fatty acid concentration. Calorimetric analysis was also performed on samples obtained by leaving the pure n-3 acid in contact with lipid aqueous dispersions (multilamellar or unilamellar vesicles) and then examining the thermotropic behavior of these systems for increasing incubation times at temperatures higher than the transitional lipid temperature. Linolenic acid (LNA) was able to migrate through the aqueous medium and successively to interact with the vesicle surface and to penetrate into the model membranes, following a flip-flop mechanism, with a faster and higher effect for unilamellar vesicles, caused by the larger lipid surface exposed, compared to the multilamellar ones, although due to the lipophilic nature of LNA, such a transfer is hindered by the aqueous medium. The relevance of the medium in LNA absorption has been well clarified by other biomimetic transfer experiments, which showed the LNA transfer from loaded multilamellar vesicles to empty vesicles. Taken together, the present findings support the hypothesis of a passive n-3 acid transport as the main route of absorption into cell membranes.

Biological Transport↗
PubMed1979

Relationship between essential fatty acid requirements of aquatic animals and the capacity for bioconversion of linolenic acid to highly unsaturated fatty acids.

1. [1-14C]linolenic acid was injected into the rainbow trout, Salmo gairdnerii, ayu, Plecoglossus altivelis, eel, Anguilla japonica, red sea bream, Chrysophrys major, rockfish, Sebastiscus marmoratus, globefish, Fugu rubripes rubripes and prawn, Penaeus japonicus (molting stage D"1-D2), and the bioconversion of linolenic acid (18:3 omega 3) to highly unsaturated fatty acids such as eicosapentaenoic (20:5 omega 3) and docosahexaenoic (22:6 omega 3) acids was investigated. 2. Linolenic acid was converted to 20:5 omega 3 and 22:6 omega 3 intensively in the rainbow trout, moderately in the ayu, eel and prawn, but slightly in the red sea bream, rockfish and globefish. 3. These results were discussed in relation to the essential fatty acid requirements of the aquatic animals.

Animals↗
PubMed1990

Uptake and incorporation of arachidonic acid and of dihomogamma-linolenic acid into tissue lipids in uterine strips isolated from ovariectomized and from ovariectomized-diabetic rats. Effects of 17-beta-estradiol.

The uptake of 14C-arachidonic acid (14C-AA) and 14C-dihomogamma-linolenic acid (14C-DGLA) into phospholipids (PLs) and neutral lipids (NLs) in uterine tissue obtained from ovariectomized controls (C) and from ovariectomized-diabetic rats (D) was studied. Uterine strips from D rats incorporate significantly less (P less than 0.05) 14C-AA into PLs than C rats. On the other hand the uptake of 14C-AA into NLs is significantly smaller (P less than 0.05) in uterine tissue from C than from D animals. The estrogenization of the C animals did not modify the incorporation of 14C-AA into PLs or NLs. On the contrary, uterine tissue obtained from D rats treated with 17-beta-estradiol incorporated significantly more labelled AA (P less than 0.05) into PLs and significantly less 14C-AA (P less than 0.05) into NLs than untreated D animals. The incorporation of 14C-DGLA into PLs shows similar pattern in uterine tissue obtained from C and D animals. Estrogenization increased significantly (P less than 0.01) in both cases, the incorporation into PLs. Regarding the incorporation of 14C-DGLA, it was clearly shown that DGLA is taken up significantly more (P less than 0.01) by NLs than by PLs, both in C and D rats. The estrogenization of C and D rats induces a significant decrease in the incorporation of 14C-DGLA into NLs in both experimental groups. The distribution of 14C-AA into the different subfractions of PLs is not uniform.(ABSTRACT TRUNCATED AT 250 WORDS)

8,11,14-Eicosatrienoic Acid↗