Showing papers on "Docosahexaenoic acid published in 1983"

Docosahexaenoic acid is a strong inhibitor of prostaglandin but not leukotriene biosynthesis

Abstract: Docosahexaenoic acid (DCHA), a major polyunsaturated acid component of fish lipid, is not a substrate for prostaglandin synthetase from ram seminal vesicles but is a strong competitive inhibitor (Ki, 0.36 microM) of the conversion by this enzyme of arachidonate (Km, 5.9 microM) to prostaglandins. In contrast, DCHA exhibits little interference to the conversion of arachidonate to metabolites on the leukotriene pathway. DCHA is a very poor substrate for the leukotriene-synthesizing system from RBL-1 cells and no formation of the C22 analog of leukotriene B could be detected from it. The C22 analog of leukotriene C4 was produced by chemical synthesis from DCHA and found to be less than 1/10,000th as active as leukotriene C4 in contracting guinea pig ileum. The DCHA used in this work was obtained in greater than 99.8% purity by a practical process developed for its separation from fish lipid. The cardiovascular protective effects ascribed to dietary intake of fish lipid by certain populations may be due in part to the biological action of DCHA, including the inhibition of prostaglandin biosynthesis.

The influence of different types of omega 3 polyunsaturated fatty acids on blood lipids and platelet function in healthy volunteers.

Abstract: 1. Five healthy subjects took a daily supplement of 20 ml of linseed oil for 2 weeks. After a break of at least 6 weeks, the same subjects took a similar amount of MaxEPA (a fish oil fraction) for 2 weeks. The linseed oil supplement provided 9.38 g of linolenic acid (18:3 ω3) and the MaxEPA supplement provided 3.03 g of eicosapentaenoic acid (20:5 ω3) and 2.93 g of docosahexaenoic acid (22:6 ω3). The effects of the supplements on plasma lipid concentrations and on the fatty acid composition of platelet phosphoglycerides were studied. 2. In a second experiment, five male subjects took 5, 10 and 20 g of MaxEPA/day in random order for 3 week periods; each experimental period was separated by a break of at least 6 weeks. These doses of MaxEPA provided 0.83, 1.67 and 3.33 g of 20:5 ω3 and 0.80, 1.61 and 3.22 g 22:6 ω3 respectively. The effects of these supplements on plasma lipid concentrations, the fatty acid composition of platelet phosphoglycerides, template bleeding time and platelet aggregation induced by collagen and the prostaglandin analogue compound U46619 were studied. 3. In the platelet lipids, the proportion of 20:5 ω3 was increased by the 20 ml linseed oil supplement but the increase was small compared with the increase brought about by even 5 g of MaxEPA/day. The proportion of arachidonic acid (20:4 ω3) was substantially decreased by the MaxEPA supplement but not by the linseed oil supplement. The ratio of 20:4 ω6/20:5 ω3 fell from 32:1 in the control periods to 11:1 with 5 g, 7:1 with 10 g and 5:1 with 20 g of MaxEPA/day. The MaxEPA supplement also led to increases in the proportions of 22:5 ω3 and 22:6 ω3 and decreases in those of 20:3 ω6 and 22:4 ω6. 4. Bleeding times tended to be prolonged with the MaxEPA supplement but did not follow any dose-dependent trend. Platelet aggregation induced by both collagen and compound U46619 was not inhibited in vitro . 5. Plasma triglyceride concentrations were lowered by the MaxEPA supplement but not by the linseed oil supplement. Plasma triglyceride concentrations were substantially lowered by 10 g and 20 g of MaxEPA/day. Total plasma cholesterol concentrations were slightly lowered and HDL cholesterol concentrations were slightly increased by 20 g of MaxEPA/day. No other significant differences were noted.

Evidence for rod outer segment lipid peroxidation following constant illumination of the rat retina.

Abstract: Constant illumination for three days (100-125 foot-candles) caused degeneration of photoreceptor cells in the albino rat retina and was accompanied by a reduction in the levels of docosahexaenoic acid (22:6 omega 3), the major polyunsaturated fatty acid in rod outer segments (ROS). An increase in the level of lipid conjugated dienes, a measure of lipid hydroperoxides, also was observed in ROS after 24-72 hours of constant illumination. These data support the suggestion that peroxidation of long-chain polyunsaturated fatty acids in ROS may be a factor in light-induced retinal degeneration.

Effect of Polyunsaturated Fatty Acids on Fetal Mouse Brain Cells in Culture in a Chemically Defined Medium

Abstract: The biochemical and morphological effects of polyunsaturated fatty acids on fetal brain cells grown in a chemically defined medium were studied. Fetal brain cells were dissociated from mouse cerebral hemispheres taken on the 16th day of gestation. After cells had grown in chemically defined medium for 8 days, the proportion of polyunsaturated fatty acids of cultured cells was only one-half of that observed at day 0 and about 1.5 times less than that of cells grown in serum-supplemented medium. Fatty acid 20:3(n-9) was present in cultured cells grown in either chemically defined or serum-supplemented medium, demonstrating the deficiency of essential fatty acids. The reduced amount of polyunsaturated fatty acids in cells grown in the chemically defined medium was balanced by an increase in monounsaturated fatty acids. The saturated fatty acids were not affected. When added at the seeding time, linoleic, linolenic, arachidonic, or docosahexaenoic acid stimulated the proliferation of small dense cells. Besides, we demonstrate that each of the four fatty acids studied was incorporated into phospholipids. Adding fatty acids of the n-6 series increased the content of n-6 fatty acids in the cells, but also provoked an increase in the n-3 fatty acids. Among several combinations of fatty acids, only 20:4 and 22:6, when added to the culture in a ratio of 2:1, restored a fatty acid profile similar to controls (i.e. in vivo tissue taken at postnatal day 5).

Combined fatty acid composition for treatment or prophylaxis of thrombo-embolic conditions

Abstract: Treatment of prophylaxis of thrombo-embolic conditions is obtained through the simultaneous administration of eicosapentaenoic acid and/or docosahexaenoic acid together with one or more of linoleic acid, γ-linolenic acid and dihomo-γ-linolenic acid, either in the form of a pharmaceutical dosage or in the form of a food product such as margarine or cooking oil.

Stimulation of free fatty acid and diacylglycerol accumulation in cerebrum and cerebellum during bicuculline-induced status epilepticus. Effect of pretreatment with alpha-methyl-p-tyrosine and p-chlorophenylalamine.

Abstract: The pool size and composition of free fatty acids (FFA) and diglycerides (DG) from the cerebrum and cerebellum of rats undergoing bicuculline-induced seizures were studied. A fourfold increase in cerebral FFA occurred 3-4 min after bicuculline injection; arachidonic and stearic acids were the principal fatty acids accumulated. Cerebellar FFA also increased, but to a lesser extent. An increased production of arachidonic acid took place in the cerebrum as a function of time after bicuculline injection. Other fatty acids produced were oleic, palmitic, and docosahexaenoic acids. A twofold increase in cerebral arachidonic acid was seen at the time of the first generalized tonic-clonic convulsion. However, a 13- to 17-fold increase in arachidonic acid was seen approximately 5-6 min after bicuculline injection. The rise in other FFA was much smaller. Stearoyl- and arachidonoyl-DG were also accumulated. The drug alpha-methyl-p-tyrosine was found to (a) potentiate the bicuculline-stimulated release of cerebellar FFA, and (b) inhibit by 70% the production of stearoyl- and arachidonoyl-DG in the cerebrum and cerebellum. Basal production of FFA was stimulated by p-chlorophenylalanine, but the drug had no effect on the bicuculline-induced changes. Hydrolysis of phospholipids enriched in stearoyl-arachidonoyl groups, such as phosphatidylinositol of excitable membranes, may be stimulated during seizures.

The influence of linseed oil diet on fatty acid pattern in phospholipids and thromboxane formation in platelets in man.

Abstract: Ten healthy volunteers daily received 30 ml linseed oil for 4 weeks in addition to the "normal" diet. The influence of linseed oil diet on the fatty acid pattern of plasma phospholipids and thromboxane formation in platelets was investigated. The fatty acid pattern was analysed by gas liquid chromatography. The alpha-linolenic, eicosapentaenoic and docosahexaenoic acids were increased (p less than 0.01), whereas linoleic and arachidonic acids were decreased (p less than 0.05) after 4 weeks of the linseed oil diet. The thromboxane formation of platelets were unchanged. Additionally the influence of HDL and LDL on PGI2 biosynthesis in pig aortic microsomes (PAM) was investigated. HDL taken from serum before and after 3 weeks of linseed oil diet and LDL taken after 3 weeks of diet stimulated the PGI2 formation in PAM, whereas LDL taken from serum before the diet period inhibited the PGI2 formation in PAM.

Altered Microsomal Phospholipid Composition in the Streptozotocin Diabetic Rat

Abstract: Streptozotocin diabetes in the rat alters liver microsomal membrane fatty acid composition. The present study was undertaken to determine if such changes in fatty acid composition were due to changes in the amount of individual phosphoglycerides or to disproportionate changes in fatty acid composition in any of the individual phosphoglycerides. The diabetic animals showed a small increase in total microsomal phospholipid, which is due to a selective increase in the phosphatidylethanolamine fraction. The changes in fatty acid composition in the total lipid extract (decreased palmitoleic, oleic and arachidonic acids and increased linoleic and docosahexaenoic acids) from the diabetic animals were present in both the major phosphoglycerides, phosphatidylcholine and phosphatidylethanolamine, with very little change in fatty acid composition in the phosphatidylserine and inositol fraction. Further studies are necessary to delineate the cause of the abnormal membrane phospholipid composition in the diabetic animal.

Dietary effect of omega-3 type polyunsaturated fatty acids on serum and liver lipid levels in rats.

Abstract: The dietary effect of omega-3 type highly polyunsaturated fatty acid concentrate (PUFA mix) was investigated on cholesterol and triglyceride levels in the serum and liver, and high density lipoprotein cholesterol (HDL-cholesterol) levels in the serum. The PUFA mix prepared from squid liver oil contained about 75% of total omega-3 type fatty acids. In rats fed the normal diet to which 3% PUFA mix was added, the levels of triglyceride, total cholesterol and phospholipid in the serum markedly decreased as compared to rats fed a 3% methyl-oleate diet. However, lipid peroxide values in the liver and serum increased in rats fed PUFA mix-diets. In the hypercholesterolemic rats, a 5% PUFA mix-diet caused growth retardation and a corresponding reduction in food intake. Lipid peroxide in the liver and serum were more elevated in rats fed diets containing 1, 3 and 5% PUFA mix than in rats fed diets containing 5% oleate or 5% linoleate. In all the rats on PUFA mix-diets, there were depression of serum total cholesterol and elevation of serum HDL-cholesterol. The ratio of HDL-cholesterol to total cholesterol increased in proportion to the amounts of dietary PUFA mix. Total cholesterol level in the liver was depressed after PUFA mix feeding.

Glycine Uptake by Cultured Human Y79 Retinoblastoma Cells: Effect of Changes in Phospholipid Fatty Acid Unsaturation

Abstract: Glycine uptake was investigated in cultured Y79 retinoblastoma cells containing different degrees of phospholipid fatty acid unsaturation. The modifications were produced by growing the retinoblastoma cells in medium supplemented with various unsaturated fatty acids. Glycine was taken up by the retinoblastoma cells through two kinetically distinguishable process. The high-affinity system is totally dependent upon extracellular Na+ and partially dependent upon Ca2+. Of the glycine taken up by retinoblastoma cells, 85-90% remains as free intracellular glycine and less than 30% is incorporated into cellular protein. When the cells are grown in a medium containing 10% fetal bovine serum as the only source of fatty acids, the phospholipids contained 23% polyunsaturated fatty acids. Under these conditions the high-affinity system has a K'm of 34.2 +/- 3.7 micrometers and a V'max of 91.2 +/- 16.2 pmol min-1 mg protein -1. The low-affinity system has a K'm of 2.7 +/- 0.4 mM and a V'max of 4.1 +/- 0.5 nmol min-1 mg protein-1. When the polyunsaturated fatty acid content of the phospholipids was increased by supplementing the medium with linolenic or docosahexaenoic acids (n-3 polyunsaturates) or linoleic or arachidonic acids (n-6 polyunsaturates), the K'm and V'max of the high-affinity glycine uptake system were increased three- to fourfold. By contrast, supplementing the medium with oleic acid, and n-9 monounsaturate, did not significantly alter the K'm or V'max for glycine uptake. The results with this model system suggest that one of the effects of the high polyunsaturated fatty acid content normally present in neural cell membranes may be a modulation of the high-affinity transport system so that it functions more efficiently in regulating glycine uptake.

The effect of polyunsaturated fatty acids on endothelial cells and their production of prostacyclin, thromboxane and platelet inhibitory activity.

Abstract: Primary cultures of human endothelial cell monolayers were incubated with albumin-bound fatty acids of the omega-3 and omega-6 families for a maximum of 24 hrs, to investigate the production of 6-keto-PGF1 alpha, TXB2 and platelet inhibitory activity (PIA). Arachidonic acid was a potent stimulator of all parameters. The release of 6-keto-PGF1 alpha was significantly reduced by equimolar concentrations of linoleic, dihomogamma linolenic and eicosapentaenoic acids, but not by linolenic acid. PIA was not similarily affected. Dihomogamma linolenic acid was also a weak stimulator of 6-keto-PGF1 alpha and PIA, but reduced the content of both in the cells after 24 hrs. Eicosapentaenoic and docosahexaenoic acids both depressed 6-keto-PGF1 alpha production but PIA was maintained after 24 hrs. Indomethacin always blocked 6-keto-PGF1 alpha and PIA production. None of the effects correlated to release of 51CR from prelabelled cells.

Changes in the Fatty Acid Patterns of Brain Phospholipids during Development of Rats Fed Peanut or Rapeseed Oil, Taking into Account Differences between Milk and Maternal Food

Abstract: The nature and amount of essential fatty acids in dietary fat play a leading part in the repartition of brain polyunsaturated fatty acids (n-3 and n-6). In order to determine precisely the respective roles of linolenic and linoleic acids in the diet on rat brain development, we used two diets in which the percentage of linolenic acid (18:3 n-3) was different. The animals were fed peanut oil (group A) or rapeseed oil (group B) during pregnancy and throughout lactation. The study of the fatty acid composition of gastric milk showed that the levels of linoleic acid (18:2 n-6) and more so linolenic acid (18:3 n-3) were much lower than in dietary fats. In group B, the 18:3 n-3 level of gastric content was about four times lower (2.4%) than in the maternal diet (8.5%) at the beginning of the suckling period and significantly increased until weaning. Analysis of the fatty acid composition of ethanolamine phosphoglycerides showed that docosapentaenoic acid delta 7-10-13-16-19 (22:5 n-3) and docosahexaenoic acid delta 4-7-10-13-16-19 (22:6 n-3) levels increased in group B in relation to group A and, on the other hand, the docosapentaenoic acid delta 4-7-10-13-16 (22:5 n-6) level decreased in group B. The sum of (n-3 + n-6) fatty acids did not change in either group B or group A. In our experimental conditions, we found no marked effect of diet composition upon conversion of linoleic acid to arachidonic acid. In summary, linolenic acid can be utilized in the brain (rather than linoleic acid) to provide long-chain polyunsaturated fatty acids and the amount of n-3 fatty acids would correlate with the desaturation activity of docosatetraenoic acid delta 7-10-13-16 (22:4 n-6) to docosapentaenoic acid delta 4-7-10-13-16 (22:5 n-6).

Changes in free fatty acids and diglycerides in mouse brain at birth and during anoxia.

Abstract: Within the first few hours of life in the mouse, marked changes were seen in brain endogenous free fatty acids (FFA). A 21% decrease in the total FFA pool occurred during the 1st h of life, and a constant value was maintained thereafter to 10 h. Polyunsaturated fatty acids displayed a different pattern of change. There was 27% less free ararhidonic acid at birth (0 h) than 1 h later. Similar values were obtained for docosahexaenoic acid at birth and at 10 h, although palmitoleic and oleic acids decreased markedly after 1 h. The polyunsaturated fatty acyl chains of diglycerides (DG) showed a statistically significant increase as a function of time after birth, despite an unchanged total DG pool size. The brains of pups subjected to 40 min of N2-anoxia immediately after delivery exhibited a decrease in FFA, especially the monoenoic components, but 60 min of anoxia yielded higher FFA levels. Anoxia induced at 10 h increased FFA and arachidonic acid was higher than when anoxia was induced at 0 h. FFA accumulation was further stimulated by raising the environmental temperature during anoxia. When anoxia was induced, DG exhibited a net increase in palmitate, oleate, and palmitoleate at 0 and 10 h. No arachidonoyl-DG accumulated at 0 h, even after 60 min of anoxia, and stearate was unchanged at 0 and 10 h. The lipid changes observed in the brain during the first hours of life suggest that the enzymatic reactions that promote accumulation of free arachidonic and docosahexaenoic acids and arachidonoyl-DG in the mature brain are present at low levels at the time of delivery. The sluggish modifications found in our study may be related to the longer resistance of newborns to oxygen deficiency.

Anoxia-induced production of methylated and free fatty acids in retina, cerebral cortex, and white matter

Abstract: The content and composition of retinal free fatty acids (FFA)† was determined during in vitro anoxia. Anoxia induced a fourfold increase in FFA production, but these lipids were modified only slightly after aerobic incubation. An even greater increase in FFA occurred when BSA was present during anoxia. In the presence of BSA, the FFA pool remaining in the anoxic tissue was larger than that observed under aerobiosis. The addition of glucose during aerobic incubation yielded even higher levels of FFA, and free docosahexaenoic acid was released rapidly and displaced into the medium during aerobic incubation. Anoxia promoted an increased release of polyenoic FFA, notably of docosahexaenoic acid. Similar FFA profiles were found in slices of cerebral cortex and white matter. Negligible amounts of endogenous longchain fatty acid methyl esters (FAME) were observed in the neural tissues after aerobiosis. However, a remarkable increase in FAME occurred during anoxia. This phenomenon was reversed by aerobic reincubation. Glucose enhanced the triacylglycerol content in anoxic brain slices. During anoxia, retina and gray matter slices generated predominantly docosahexaenoate, arachidonate, stearate, and palmitate methyl esters, whereas white matter slices yielded other FAME. FAME that were present in liver and heart were not altered by anoxic incubation, even when FFA increased. It is concluded that FFA are derived from phospholipid deacylation, and that the in vitro retina is a more suitable CNS model for membrane lipid studies than brain slices, because it can maintain an almost constant FFA pool during short-term incubations under aerobic conditions. Also, the formation of FAME in the nervous system may be a defense mechanism aimed at lowering FFA levels when neurons are exposed to extreme oxygen deprivation.

Differences in the fatty acid composition of atrial and ventricular phospholipids of rat heart following standard and lipid-supplemented diets

Abstract: 1. 1. The major saturated fatty acids of the phospholipids of rat heart atria and ventricles are similar and are not greatly altered by supplementing the diet with widely different types of lipid. 2. 2. There are important differences in the relative proportions of the major unsaturated fatty acids of the phospholipids of these anatomically and functionally distinct regions of the heart. 3. 3. The proportions of linoleic (C18:2, η-6) and docosahexaenoic (C22:6, η-3) acid are significantly higher in the ventricles than in the atria; the proportions of oleic (C18:1, η-9) arachidonic (C20:4, η-6) and docosatetraenoic acids (22:4, η-6) are higher in atria. 4. 4. The differences in unsaturated fatty acid profiles persist even after twelve months of feeding lipid supplements of sunflower seed oil (SSO) or sheep kidney (perirenal) fat (SKF). 5. 5. However, the ratios of arachidonic to docosahexaenoic acid in both tissues are changed by decreasing the intake of linoleic acid, which apparently favours the conversion of dietary linolenic (C18:3, η-3) to docosahexaenoic acid. The level of docosahexaenoic acid is greater in the ventricles than in the atria, and greatest when the animals were fed SKF diet. 6. 6. The physiological and pharmacological differences in ventricles and atria may arise from differences as fundamental as the phospholipid fatty acid composition of cardiac membranes.

Effect of cross-fostering rats at birth on the normal supply of essential fatty acids during protein deficiency.

Abstract: The effect of protein deficiency on the activity of A6 desaturase in the mother during lactation was determined in the liver microsomal fraction and the fatty acid composition of milk lipids from the analyzed stomach contents. The activity of A6 desaturase was profoundly affected by protein deprivation during pregnancy and only reached the values of controls at about 10 days after parturition. This fact did not affect the fatty acid pattern of milk lipids and no significant differences in the contents of arachidonic acid were detected between the two groups. Nevertheless, protein de ficiency apparently affected milk production. The effects of protein deprivation on the supply of polyenoic acids of cross-fostering rats at birth from protein-deficient to protein- sufficient diets and vice versa, and rats maintained during pregnancy and lactation on a low protein or control diet were examined. The fatty acid pattern of liver phospholipids of the four groups under study was determined and used as a biochemical parameter for evaluating polyenoic acid status. Protein deficiency markedly affected the fatty acid pattern of liver phospholipids. A significant decrease of both arachidonic and docosa- hexaenoic acids was observed. This fatty acid pattern was reversed when protein-de ficient animals were placed on the control diet at birth. On the other hand, the fatty acid composition of controls was negatively affected by cross-fostering to a deficient diet. The findings from the present experiment provide evidence that the negative effect of protein malnutrition appears to be promoted at least in part, by the effect of protein depletion on the supply of polyenoic acids for normal development and metabolic adaptations. J. Nutr. US: 314-319, 1983.

Inhibition of the uterine binding of estrogens by unsaturated fatty acids in immature female rats

Abstract: We demonstrate that the interactions between the uterine cytosol proteins of 24 day old Rats and estradiol-17 beta (E2) are significantly influenced by physiological concentrations of non esterified fatty acids (2. 10(-4)M). We show that the specific binding of the hormone to the 8S uterine receptor, is markedly inhibited (50-80%) by the unsaturated fatty acids. The observed inhibition is a function both of acid dose and acid unsaturation degree. The polyunsaturated arachidonic and docosahexaenoic acids are the strongest inhibitors, whereas the saturated palmitic and stearic acids do not displace the E2 from the 8S receptor.

The levels of essential unsaturated fatty acids in human milk on the 3rd, 4th, 5th, and 6th days after labour.

Abstract: The composition of fatty acids in human milk lipids was determined in 41 women on the 3rd, 4th, 5th and 6th days after labour by the method of gas chromatography. In these investigations no significant differences were demonstrated in the fatty acids in the lipid fractions between these consecutive days. The level of polyunsaturated fatty acids of the n-6 and n-3 groups was about 11.9-13.6%, including linoleic acid (18:2, n-6) about 7.7-9.8%, and alpha-linolenic acid (18:3, n-3) about 0.7-1%. In the analysis group of n-6 fatty acids the determined acids were: linoleic acid (18:2, n-6), gamma-linolenic acid (18:3, n-6), eicosadienoic acid (20:2, n-6), eicosatrienoic acid (20:3, n-6), arachidonic acid (20:4, n-6), docosahexaenoic acid (22:6, n-6). From the group of n-3 acids the identified ones were: alpha-linolenic acid (18:3, n-3), eicosapentaenoic acid (20:5, n-3), docosapentaenoic acid (22:5, n-3) and docosahexaenoic acid (22:6, n-3). The obtained quotients of fatty acids n-6 through n-3 on the consecutive days were: 7.2:1-7.8:1, indicating a too low level of the n-3 acids in the investigated milk. The acids prevailing in human milk lipids were: oleic (18:1, n-9) and palmitic (16:0) which accounted for 37-39% and 25-26% respectively. The polyunsaturated to saturated fatty acid ratio (P:S) ranged from 0.28 to 0.33.

Arachidonic acid and other long-chain fatty acids in canine ceroid lipofuscinosis. Distribution in glycerolipids, metabolism, and pathophysiological correlations.

Abstract: Dogs with canine ceroid lipofuscinosis (CCL)† show an abnormal EEG as early as 5 mo of age and exhibited either severe disorganization or very low amplitudes by 24 mo. Ceroid particles accumulate with age and, within neurons, have a unique characteristic appearance consisting of lamellar patterns enclosed by a single unit membrane. Although the etiology of their formation has not been fully elucidated, isolated particles are enriched in phospholipids. Our present studies have examined microsomal enzymes involved in phospholipid synthesis and turnover and demonstrate that the acyl group composition of cerebral lipids from animals with CCL is similar to that from controls. However, the activation of palmitic, linoleic, arachidonic, and docosahexaenoic acids into their Coenzyme A thiol ester forms was significantly lower in cerebral and cerebellar microsomes of the diseased dogs than in those of the controls. In addition, the incorporation of arachidonic acid into phospholipids was significantly decreased in affected animals. These results suggest that the metabolism of arachidonic acid plays an important role in the pathogenesis of ceroid lipofuscinosis.