Effects of soybean oil emulsion and eicosapentaenoic acid on stress response and immune function after a severely stressful operation.
OBJECTIVE: To investigate the effects of soybean oil emulsion and oral or enteral administration of eicosapentaenoic acid (EPA) on stress response, cytokine production, protein metabolism, and immune function after surgery for esophageal cancer. SUMMARY BACKGROUND DATA: It has been reported that safflower oil, rich in n-6 polyunsaturated fatty acid (n-6 PUFA), affects the survival rate of septic animals and decreases the immune function. It has also been reported that the administration of fish oil, in contrast, reduces these stress responses and stress-induced immunosuppression. In humans, the effects of soybean oil emulsion and the administration of EPA on stress response and immune function after surgery have not been established. METHODS: Patients who underwent esophagectomy with thoracotomy were divided into three groups. Seven patients were fed by total parenteral nutrition (TPN) with soybean oil emulsion, which accounted for 20% of total calories. Seven patients were given oral or enteral administration of 1.8 g/day EPA, in addition to TPN with soybean oil emulsion. Nine patients served as the control group; these patients received fat-free TPN. Serum interleukin-6 (IL-6), C-reactive protein, concanavalin A (con A)- or phytohemagglutinin (PHA)-stimulated lymphocyte proliferation, natural killer cell activity, and stress hormones were measured. RESULTS: The postoperative level of serum IL-6 was significantly higher in the group receiving soybean oil emulsion than in the fat-free group. Oral or enteral supplementation of EPA with soybean oil emulsion significantly reduced the level of serum IL-6 compared with the patients receiving soybean oil emulsion. Con A- or PHA-stimulated lymphocyte proliferation decreased significantly on postoperative day 7 in all groups of patients. The supplementation of EPA with soybean oil emulsion significantly improved the lymphocyte proliferation and natural killer cell activity on postoperative day 21 compared with the group receiving soybean oil emulsion. CONCLUSIONS: Soybean oil emulsion amplifies, and the supplementation of EPA reduces, the stress response and stress-induced immunosuppression. (+info)
Effects of docosahexaenoic and eicosapentaenoic acid on lipid metabolism, eicosanoid production, platelet aggregation and atherosclerosis in hypercholesterolemic rats.
Exogenously hypercholesterolemic (ExHC) rats were fed on an atherogenic diet supplemented with 1% each of either ethyl ester docosahexaenoic acid [EE-DHA, 22:6(n-3)], ethyl ester eicosapentaenoic acid [EE-EPA, 20:5(n-3)] or safflower oil (SO) for 6 months. The rats fed on the diets containing EE-EPA or EE-DHA, compared with those fed on SO, had lower serum cholesterol and triacylglycerol levels, less aggregation of platelets and slower progress of intimal thickening in the ascending aorta. Relative to the SO-fed rats, both of the (n-3) fatty acid-fed rats had a significantly reduced proportion of arachidonic acid in the platelet and aortic phospholipids, and lower production of thromboxane A2 by platelets and of prostacyclin by the aorta. These results suggest that EPA and DHA are similarly involved in preventing atherosclerosis development by reducing hypercholesterolemia and modifying the platelet functions. (+info)
Dietary effect of EPA-rich and DHA-rich fish oils on the immune function of Sprague-Dawley rats.
The dietary effect of fish oils (FOs) rich in eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on the immune function of Sprague-Dawley rats was compared with that of safflower oil. After 3 weeks of feeding at the 10% level of a dietary fat, the IgG and IgM production by splenocytes and IgG production by mesenteric lymph node (MLN) lymphocytes were significantly higher in the FO-fed rats, while no significant difference was found in IgA or IgE productivity by both the spleen and MLN lymphocytes. In the FO-fed rats, peritoneal exudate cells released a lower amount of LTB4, reflecting their lower arachidonic acid level, and a higher amount of LTB5, reflecting their higher EPA level in phospholipids. On these EPA-rich FO exerted a stronger effect than DHA-rich FO immune functions. (+info)
Low C18 to C20 fatty acid elongase activity and limited conversion of stearidonic acid, 18:4(n-3), to eicosapentaenoic acid, 20:5(n-3), in a cell line from the turbot, Scophthalmus maximus.
The TF cell line, derived from a top predatory, carnivorous marine teleost, the turbot (Scophthalmus maximus), is known to have a limited conversion of C18 to C20 polyunsaturated fatty acids (PUFA). To illuminate the underlying processes, we studied the conversions of stearidonic acid, 18:4(n-3), and its elongation product, 20:4(n-3), in TF cells and also in a cell line, AS, derived from Atlantic salmon (Salmo salar), by adding unlabelled (25 microM), U-14C (1 microM) or deuterated (d5; 25 microM) fatty acids. Stearidonic acid, 18:4(n-3), was metabolised to 20:5(n-3) in both cells lines, but more so in AS than in TF cells. Delta5 desaturation was more active in TF cells than in AS cells, whereas C18 to C20 elongation was much reduced in TF as compared to AS cells. Only small amounts of docosahexaenoic acid (22:6(n-3)) were produced by both cell lines, although there was significant production of 22:5(n-3) in both cultures, especially when 20:4(n-3) was supplemented. We conclude that limited elongation of C18 to C20 fatty acids rather than limited fatty acyl Delta5 desaturation accounts for the limited rate of conversion of 18:3(n-3) to 20:5(n-3) in the turbot cell line, as compared to the Atlantic salmon cell line. The results can account for the known differences in conversions of C18 to C20 PUFA by the turbot and the Atlantic salmon in vivo. (+info)
Effect of prostanoids and their precursors on the aggregation of rainbow trout thrombocytes.
The role of prostanoids and their precursor fatty acids in the aggregatory response of thrombocytes (platelet equivalents of fish) from the rainbow trout, Oncorhynchus mykiss, was studied. Aggregation of these cells was induced by the thromboxane mimetic U-46619 or arachidonic acid (AA) in the presence of human or trout fibrinogen. The production of TXB2/3 by thrombocytes in response to stimulation with AA was inhibited by aspirin, ibuprofen, and indomethacin. However, thrombocyte aggregation in response to AA stimulation was not significantly altered by these agents at the concentrations tested (10-100 microM), with the exception of indomethacin at 20 and 40 microM. Effects on cytosolic calcium concentration have been suggested as an alternative mechanism for the inhibitory action of indomethacin on human platelet aggregation. The present study, however, failed to identify this as a mechanism for the inhibition of U-46619-induced trout thrombocyte aggregation by indomethacin. The polyunsaturated fatty acids docosahexaenoic acid and eicosapentaenoic acid both exhibited an inhibitory effect on U-46619-induced thrombocyte aggregation similar to that observed with mammalian platelets. Unlike the case in mammalian hemostasis, prostacyclin inhibited thrombocyte aggregation only at high concentrations (>5 microM). Prostaglandin E2, however, inhibited thrombocyte aggregation at much lower concentrations (>0.01 microM), suggesting that it may be the major inhibitory eicosanoid in trout. (+info)
Molecular recognition of fatty acids by peroxisome proliferator-activated receptors.
The peroxisome proliferator-activated receptors (PPARs) are nuclear receptors for fatty acids (FAs) that regulate glucose and lipid homeostasis. We report the crystal structure of the PPAR delta ligand-binding domain (LBD) bound to either the FA eicosapentaenoic acid (EPA) or the synthetic fibrate GW2433. The carboxylic acids of EPA and GW2433 interact directly with the activation function 2 (AF-2) helix. The hydrophobic tail of EPA adopts two distinct conformations within the large hydrophobic cavity. GW2433 occupies essentially the same space as EPA bound in both conformations. These structures provide molecular insight into the propensity for PPARs to interact with a variety of synthetic and natural compounds, including FAs that vary in both chain length and degree of saturation. (+info)
Prevention of sudden cardiac death by dietary pure omega-3 polyunsaturated fatty acids in dogs.
BACKGROUND: Rat diets high in fish oil have been shown to be protective against ischemia-induced fatal ventricular arrhythmias. Increasing evidence suggests that this may also apply to humans. To confirm the evidence in animals, we tested a concentrate of the free fish-oil fatty acids and found them to be antiarrhythmic. In this study, we tested the pure free fatty acids of the 2 major dietary omega-3 polyunsaturated fatty acids in fish oil: cis-5,8,11,14, 17-eicosapentaenoic acid (C20:5omega-3) and cis-4,7,10,13,16, 19-docosahexaenoic acid (C22:6omega-3), and the parent omega-3 fatty acid in some vegetable oils, cis-9,12,15-alpha-linolenic acid (C18:3omega-3), administered intravenously on albumin or a phospholipid emulsion. METHODS AND RESULTS: The tests were performed in a dog model of cardiac sudden death. Dogs were prepared with a large anterior wall myocardial infarction produced surgically and an inflatable cuff placed around the left circumflex coronary artery. With the dogs running on a treadmill 1 month after the surgery, occlusion of the left circumflex artery regularly produced ventricular fibrillation in the control tests done 1 week before and after the test, with the omega-3 fatty acids administered intravenously as their pure free fatty acid. With infusion of the eicosapentaenoic acid, 5 of 7 dogs were protected from fatal ventricular arrhythmias (P<0.02). With docosahexaenoic acid, 6 of 8 dogs were protected, and with alpha-linolenic acid, 6 of 8 dogs were also protected (P<0.004 for each). The before and after control studies performed on the same animal all resulted in fatal ventricular arrhythmias, from which they were defibrillated. CONCLUSIONS: These results indicate that purified omega-3 fatty acids can prevent ischemia-induced ventricular fibrillation in this dog model of sudden cardiac death. (+info)
Incorporation of exogenous lipids modulates insulin signaling in the hepatoma cell line, HepG2.
The lipid content of cultured cells can be experimentally modified by supplementing the culture medium with specific lipids or by the use of phospholipases. In the case of the insulin receptor, these methods have contributed to a better understanding of lipid disorder-related diseases. Previously, our laboratory demonstrated that experimental modification of the cellular lipid composition of an insulin-sensitive rat hepatoma cell line (ZHC) resulted in an alteration in insulin receptor binding and biological action (Bruneau et al., Biochim. Biophys. Acta 928 (1987) 287-296/297-304). In this paper, we have examined the effects of lipid modification in another hepatoma cell line, HepG2. Exogenous linoleic acid (LA, n-6), eicosapentaenoic acid (EPA, n-3) or hemisuccinate of cholesterol (CHS) was added to HepG2 cells, to create a cellular model in which membrane composition was modified. In this model, we have shown that: (1) lipids were incorporated in treated HepG2 cells, but redistributed differently when compared to treated ZHC cells; (2) that insulin signaling events, such as insulin receptor autophosphorylation and the phosphorylation of the major insulin receptor substrate (IRS-1) were altered in response to the addition of membrane lipids or cholesterol derived components; and (3) different lipids affected insulin receptor signaling differently. We have also shown that the loss of insulin receptor autophosphorylation in CHS-treated cells can be correlated with a decreased sensitivity to insulin. Overall, the results suggest that the lipid environment of the insulin receptor may play an important role in insulin signal transduction. (+info)