Effects of dietary fish oil on lung phospholipid fatty acid composition and intrinsic pulmonary vascular reactivity

Effects of dietary fats (fish, olive and high-oleic-acid sunflower oils) on lipid composition and antioxidant enzymes in rat liver

The effects of two oleic-acid-rich diets (containing olive oil, OO, and high-oleic-acid sunflower oil, HOSO) on plasma and liver lipid composition detoxification enzyme activities, were compared with those of a fish-oil (FO) diet and a control diet. Compared with the control diet, plasma and hepatic total triacylglycerol concentrations were increased in the animals fed on the HOSO and OO diets and decreased in those fed on the FO diet. The animals fed on FO showed the highest level of cholesterol in the liver and had lower plasma cholesterol concentrations when compared with those fed on the two oleic-acid-rich diets. In comparison with the animals fed on the diets enriched in oleic acid, the FO group showed higher hepatic levels of polyunsaturated fatty acids of then-3 series and lower levels of fatty acids of then-6 series. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (1) significantly higher activities of catalase (EC1.11.1.6) glutathione peroxidase (EC1.11.1.9) and Cu/Zn superoxide dismutase (EC1.15.1.1); (2) no differences in the NADPH-cytochromecreductase (EC1.6.99.3) activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly ton-3 lipids may enhance the efficiency of the antioxidant defence system. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid but different contents of natural antioxidants, had similar effects on the antioxidant enzyme activities measured.

Effects of eicosapentaenoic and gamma-linolenic acids (dietary lipids) on pulmonary surfactant composition and function during porcine endotoxemia

STUDY OBJECTIVES

To investigate whether a diet enriched with fish and borage oils, with their high polyunsaturated fatty acid (PUFA) content, alters surfactant composition and function during endotoxemia.

DESIGN

Prospective, randomized, blinded, controlled animal study.

SETTING

Research laboratory at a medical center.

PARTICIPANTS

Thirty-six 15- to 25-kg, disease-free, castrated male pigs. DIETS AND MEASUREMENTS: Three groups of pigs (n = 12 per group) were fed for 8 days diets containing either omega-6 fatty acids (FAs) (corn oil; diet A), or omega-3 FAs (fish oil; diet B), or a combination of omega-6 and omega-3 FAs (borage and fish oils; diet C). Eight of 12 pigs in each group received a 0.1-mg/kg bolus of Escherichia coli endotoxin followed by a continuous infusion (0. 075 mg/kg/h). One lung was subsequently isolated ex vivo, and pressure-volume curves were measured. The contralateral lung was lavaged, and surfactant was analyzed for total and individual phospholipids and FA composition. Minimum and maximum surface tension was measured by bubble surfactometry.

RESULTS

Pigs fed either diet B or C had increased oleic acid (C(18:1) omega-9), eicosapentaenoic acid (EPA; C(20:5) omega-3), docosahexaenoic acid (C(22:6) omega-3), and total omega-3 and monounsaturated FAs in their surfactant PUFA pools. The relative percentage of linoleic acid (C(18:2) omega-6) and total omega-6 FAs were significantly lower from pigs fed diets B and C compared with diet A. Palmitic acid (C(16:0)) concentrations, the primary FA in surfactant, had a tendency to be lower in pigs fed diets B and C. There were no demonstrable effects on surfactant function or pulmonary compliance.

CONCLUSIONS

Diets containing EPA or EPA and gamma-linolenic acid altered the PUFA composition of pulmonary surfactant, but without demonstrable effects on surfactant function during porcine endotoxemia.

The use of an intravenous fish oil emulsion enriched with omega-3 fatty acids in patients with cystic fibrosis

The effects of parenteral nutrition supplemented with a lipid emulsion enriched with the omega-3 fatty acids (FA), eicosapentaenoate (20:5n-3) and docosahexaenoate (22:6n-3), derived from fish oil were compared to a standard lipid emulsion containing omega-6 FA in patients with cystic fibrosis (CF). Patients were randomized to receive either Omegavenous 10%, which contains fish oil (IFO), or Liposyn III 10% (control) daily for 1 mo at a dose of 150 mg/kg. There were no observed allergic or toxic reactions, no abnormalities in liver function tests or coagulation parameters. To assess the bioavailability of the lipid administered, measurement of plasma free fatty acid (FFA) levels were made of the essential FA. There were no adverse changes in plasma levels of the omega-6 FA (18:2n-6, 18:3n-6, 20:3n-6, and 20:4n-6), and plasma levels of the omega-3 FA (20:5n-3 and 22:6n-3) increased significantly during the 1-mo study. There were no significant changes in plasma FFA profiles of the essential FA for the patients receiving the control lipid. The effect of treatment on pulmonary function was also investigated. There were no significant changes in FVC, FEV1, PEFR, FEV1/ FVC, or FEF25-75 (absolute value or percentage) over the 4 weeks of study in the group receiving IFO or control. This preliminary investigation suggests that intravenous administration of fish oils enriched with long chain omega-3 FA to patients with CF is safe and bioavailable.

The effects of dietary fish oil on alveolar type II cell fatty acids and lung surfactant phospholipids

The purpose of this study was to determine the responsiveness of alveolar type II cells to dietary fish oil and the consequent effects on alveolar and lung surfactant. Rats were fed a corn oil or a fish oil diet for four weeks. Dietary n-3 fatty acids were readily incorporated into the type II cell phospholipids as indicated by higher levels of eicosapentaenoic acid (2.77 +/- 0.10%) and docosahexaenoic acid (1.63 +/- 0.10%) in the group receiving the fish oil diet. The elevated levels of n-3 fatty acids were accompanied by concomitant reduction in arachidonic acid and linoleic acid. Neither eicosapentaenoic acid nor docosahexaenoic acid was incorporated into type II cell triacylglycerols. Feeding a fish oil containing diet increased surfactant phospholipids, particularly 1,2-disaturated acyl phosphatidylcholines in whole lung compared to a corn oil diet. However, the amount of surfactant found in the alveolus was not different between the two diet treatment groups. The results suggest that dietary n-3 fatty acids stimulate synthesis and/or inhibit degradation of lung surfactant without altering surfactant secretion in alveoli.