The protective effect of dietary fish oil on murine lupus

Dietary marine lipids markedly reduce the severity of glomerulonephritis and its associated mortality in inbred strains of mice developing autoimmune disease, a model for human systemic lupus erythematosus. We report here the influence of varying the dose of menhaden oil and the timing of its administration on the mortality of female (NZB x NZW) F₁ mice. After ingesting 25 wt% menhaden oil (MO) for periods of 1.5 weeks to 12 months, there was a stable content of tissue n-3 fatty acids, with total n-3 fatty acids of 28% and 35% in spleen and liver, respectively. The extent of protection from mortality was dependent on the dose of MO with marked protection at doses of 11 to 25%, marginal protection at 5.5% and no protection at 2.5% MO. Delay in the institution of MO until ages 5 or 7 months still resulted in large reductions of mortality. Conversely, institution of a MO diet from 6 weeks until ages 5 to 7 months followed by a change to beef tallow resulted in little protection. Serum levels of 4 cyclooxygenase products were reduced ranging from 26 to 76% in mice fed MO diets, compared to mice fed beef tallow, based on radioimmunoassay. The degree of reduction of mortality on different doses of MO was correlated best with tissue levels of C22:5, and levels of C20:5 and C22:6 were similar at high and low doses of MO, suggesting that levels of 22:5 may be related to the protective effects of marine lipids on autoimmune disease.     

Heart and liver fatty acid composition and vitamin E content in miniature swie fed diets containing corn and menhaden oils

Female miniature swine, 4–11 yr, were fed 15% fat diets containing n-3 and/or n-6 polyunsaturated fat for 6 months, at 1.95 g fat/kg body weight. Liver lipids from menhaden oil-fed minipigs were elevated in the n-3 fatty acids: 20:5, 22:5 and 22:6, but heart lipids only in 20:5 and 22:6. Liver cell plasma membrane was elevated in 20:5, 22:5 and 22:6 and lowered in the n-6 acids 18:2 and 20:4 in menhaden oil-fed animals, to a greater extent than in the total tissue lipids. Liver α-tocopherol tended to decrease upon feedin menhaden oil, but heart α-tocopherol concentrations were not affected.     

Interactions of saturated, n-6 and n-3 polyunsaturated fatty acids to modulate arachidonic acid metabolism

Anti-thrombotic effects of omega-3 (n-3) fatty acids are believed to be due to their ability to reduce arachidonic acid levels. Therefore, weanling rats were fed n-3 acids in the form of linseed oil (18:3n-3) or fish oil (containing 20:5n-3 and 22:6n-3) in diets containing high levels of either saturated fatty acids (hydrogenated beef tallow) or high levels of linoleic acid (safflower oil) for 4 weeks. The effect of diet on the rate-limiting enzyme of arachidonic acid biosynthesis (delta 6-desaturase) and on the lipid composition of hepatic microsomal membrane was determined. Both linseed oil- or fish oil-containing diets inhibited conversion of linoleic acid to gamma-linolenic acid. Inhibition was greater with fish oil than with linseed oil, only when fed with saturated fat. delta 6-Desaturase activity was not affected when n-3 fatty acids were fed with high levels of n-6 fatty acids. Arachidonic acid content of serum lipids and hepatic microsomal phospholipids was lower when n-3 fatty acids were fed in combination with beef tallow but not when fed with safflower oil. Similarly, n-3 fatty acids (18:3n-3, 20:5n-3, 22:5n-3, and 22:6n-3) accumulated to a greater extent when n-3 fatty acids were fed with beef tallow than with safflower oil. These observations indicate that the efficacy of n-3 fatty acids in reducing arachidonic acid level is dependent on the linoleic acid to saturated fatty acid ratio of the diet consumed.     

Dietary fat source and cholesterol interactions alter plasma lipids and tissue susceptibility to oxidation in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats

Due to the potential for dietary fat source to alter plasma lipids and tissue antioxidant status, we hypothesized that blends of saturated, n-6 and n-3 fats with cholesterol would affect LDL and tissue susceptibility to in vitro oxidation. The effects of dietary fat blends of butter (B), beef tallow (T), soybean oil (SBO) or menhaden oil (MO) and cholesterol on systolic blood pressure (SBP), plasma lipoproteins and tissue susceptibility to glutathione (GSH) depletion and lipid peroxidation (TBARS) were examined in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. SBP in SHRs was higher (p < 0.001) than in WKYs at 13-weeks of age but was not altered by dietary fat or cholesterol. LDL- and HDL-cholesterol were greater (p < 0.001) in WKY than SHR. LDL-cholesterol and (VLDL7- + LDL-cholesterol)/HDL-cholesterol ratios were reduced in MO vs. B, T and SBO groups. HDL-cholesterol levels tended to be lower and greater in B and MO groups, respectively vs. T and SBO groups. Initial LDL fluorescence was greater (p < 0.001) in high- vs. low-cholesterol groups. The change in LDL fluorescence was reduced (p < 0.001) in high-cholesterol groups, and MO vs. B, T and SBO rats. MO fed rats had reduced (p < 0.001) RBC, heart and liver GSH depletion and reduced (p < 0.01) tissue TBARS and RBC MDA production. In summary, a moderate level of dietary MO did not increase tissue and LDL in vitro oxidizability in SHR and WKY rats. High dietary cholesterol exhibited a protective effect against in vitro oxidation of LDL and selected tissues.     

Dietary n-3 fatty acids alter the contractile response to thromboxane A(2) agonists of porcine coronary arteries

Dietary supplementation with marine fish oils rich in n-3 fatty acids reduces circulating thromboxane A(2) (TxA(2)). However, the effects on thomboxane A(2) receptor mediated vascular reactivity are uncertain. The aim of this study was to test the hypothesis that dietary modification of TxA(2) levels alters vascular responsiveness to TxA(2) analogues. Juvenile female white pigs were fed a diet enriched in either 5% (w/w) fish oil or beef tallow for 6 weeks. Serum and myocardial tissue levels of eicosapentaenoic and docosahexaenoic acid reached a plateau during this period. Vascular responses were measured in isolated coronary arterial rings with intact endothelium by isometric tension measurement. Arteries from pigs fed fish oil produced a greater maximum vasoconstrictor tension to the TxA(2) analogue U46619 than did rings from pigs fed beef tallow (120 +/- 6% compared to 92 +/- 8%, values represented as a percentage relative to the maximum vasoconstrictor effect obtained to KCl, regression analysis, analysis of variance, P 相似文献   

Attenuation of mammary duct development by menhaden oil in BALB/c mice

The predominant polyunsaturated fatty acids of the n-6 family found in corn oil (CO) are crucial for normal mammary duct formation when fed to animals. However, as shown here, not all polyunsaturated fatty acids are equally effective in stimulating mammary gland development. The n-3 fatty acids in a 10% menhaden oil (MO) diet fed to mice effectively reduced both the diameter and the length of the growing mammary ducts. Previously, we demonstrated a similar reduction in duct growth by feeding a 10% fat diet high in those saturated fats found in hydrogenated cotton seed oil. The inhibited rate of duct maturation caused by hydrogenated cotton seed oil was reversed when the mice were allowed to mature on a diet containing n-6 fatty acids prior to feeding the saturated fat diet. The addition of 1% CO to a 9% hydrogenated cotton seed oil diet fed to immature mice was also sufficient to restore duct growth. Mice fed menhaden oil diets, on the other hand, continued to show impaired ductal growth well into adulthood. Examination of the ovaries from MO-fed mice as compared with CO-fed mice revealed significantly fewer corpora lutea. When exogenous progesterone was given to MO-fed mice, ductal growth was partially restored, but not to the extent seen in mice fed corn oil diets. Investigation of the fatty acid contents of livers of these mice revealed reduced amounts of arachidonate (20:4) in MO-fed mice when compared with CO-fed animals. The addition of 1% CO to the 9% MO diets did not alter the arachidonate content, indicating a block in the conversion of linoleate (18:2) to 20:4 by the n-3 fatty acids. Hence, dietary n-6 fatty acids are essential for normal mammary ductal development when fed prior to maturation. Although saturated rats are ineffective, n-3 fatty acids can partially substitute for the required n-6 fatty acids in both ductal and ovarian development.     

Modulation of phorbol ester-elicited events in mouse epidermis by dietary n-3 and n-6 fatty acids

Because arachidonic acid-derived eicosanoids are potent modulators of hyperproliferation and inflammation during skin tumor promotion with the phorbol ester, 12-0-tetradecanoylphorbol-13-acetate (TPA) (17, 18), it was hypothesized that dietary modification of epidermal fatty acids might modulate TPA-induced biochemical events in mouse skin. Semipurified diets containing 10% total fat composed of corn oil (CO) or a combination of CO and menhaden oil (MO) or coconut oil (CT) were fed to SENCAR mice for 4 weeks. Fatty acid composition of epidermal phospholipids generally reflected fatty acid composition of dietary oils fed to the mice. Since fatty acid-derived eicosanoids are thought to be essential in tumorigenesis, we compared the effects of dietary fats on prostaglandin E (PGE) production in epidermis treated with a single dose of TPA. TPA-induced PGE production in mouse epidermis from mice fed the MO diet was significantly reduced compared to PGE production in epidermal homogenates from mice fed the CO or CT diets. Type of dietary fats did not appear to modulate TPA-induced vascular permeability, however hyperplasia was slightly elevated in skins of mice fed MO. The subcellular distribution of protein kinase C, the plasma membrane receptor for TPA predominantly located in the cytosol (80%), was altered in epidermis from mice fed the MO diet compared to preparations from mice fed CO or CT diets which exhibited normal protein kinase C distribution. Our results suggest that n-3 rich dietary lipids modulate TPA-elicited events in mouse skin to a greater extent than diets containing higher proportions of saturated or n-6 fatty acids.     

Fish oil reduces cholesterol and arachidonic acid levels in plasma and lipoproteins from hypercholesterolemic chicks

The value of fish oil for prevention and/or treatment of human atherosclerosis has not been fully established. This study shows that replacement of saturated fat in young chick diet with menhaden oil produced a significant reversion of the hypercholesterolemia previously induced by coconut oil feeding. Fish oil also produced a clear decrease of plasma triacylglycerol levels. Coconut oil increased the percentages of 12:0 and 14:0 fatty acids, while menhaden oil increased those of 20:5 n-3 and 22:6 n-3. Percentages of 20:4 n-6, 18:2 n-6 and 18:1 n-9 significantly decreased by fish oil addition to the diet. Total cholesterol, phospholipid and protein contents of high and low density lipoproteins increased by coconut oil feeding. When coconut oil was replaced by menhaden oil, total cholesterol was significantly reduced in high, low and very low density lipoproteins. All chemical components of VLDL were decreased by menhaden oil feeding. Our results show a strong hypocholesterolemic effect of menhaden oil when this fat was supplemented to hypercholesterolemic chicks. The clear decrease found in arachidonic acid content of chick plasma and lipoproteins may contribute to the beneficial effects of fish oil consumption by lowering the production of its derived eicosanoids.     

Seasonal changes in lipid classes and fatty acid composition in the digestive gland of Pecten maximus

Seasonal variations in lipid classes and fatty acid composition of triacylglycerols and phospholipids in the digestive gland of Pecten maximus were studied over a period of 16 months. Acylglycerols predominated (19-77% of total lipids), in accordance with the role of the digestive gland as an organ for lipid storage in scallops. Seasonal variations were mainly seen in the acylglycerol content, while phospholipids (2.5-10.0% of total lipids) and sterols (1.9-7.4% of total lipids) showed only minor changes. The most abundant fatty acids were 14:0, 16:0, 18:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 18:4(n-3), 20:5(n-3) and 22:6(n-3) and these showed similar seasonal profiles in both, triacylglycerol and phospholipid fractions. In contrast to the phospholipid fraction, the triacylglycerol fraction contained more 20:5(n-3) than 22:6(n-3). In three phospholipid samples we noted a high percentage of a 22-2-non-methylene-interrupted fatty acid, previously described to have a structural role in several bivalve species. The main polyunsaturated fatty acids displayed important seasonal variations parallel to those of the acylglycerols, suggesting good nutritional conditions. A positive correlation existed between the level of saturated fatty acids and temperature, whereas the levels of polyunsaturated fatty acids correlated negatively with temperature.     

The Composition of fatty acids and aldehydes of the marine bryozoans <Emphasis Type="Italic">Berenicea meandrina</Emphasis> and <Emphasis Type="Italic">Dendrobeania flustroides</Emphasis> (Bryozoa: Gymnolaemata)

This study examines the composition of lipids, fatty acids, and fatty aldehydes in two marine bryozoan species, Berenicea meandrina and Dendrobeania flustroides, from the Sea of Okhotsk. The share of neutral lipids was up to 57.3% in D. flustroides and 54.9% in B. meandrina; the share of polar lipids was 33.2 and 40.4%, respectively. In all, 57 fatty acids (FA) and 9 aldehydes were identified in total lipids. The main FAs were 16:0, 18:0, 22:6n-3, and 20:5n-3. The content of branched saturated FA in bryozoans was on the average 6.4%. Three isomers of 16:1 (n-9, n-7, and n-5), five isomers of 18:1 (n-13, n-11, n-9, n-7, and n-5), four isomers of 20:1 (n-13, n-11, n-9, and n-7), as well as 22:1n-9 and 22:1n-13 were found; the presence of 7-methyl-6-hexadienoic acid (on the average, 3.0% of total FAs) was demonstrated. Non-methylene-inter-rupted FAs contributed 8.9 and 1.6% of the total FAs in D. flustroides and B. meandrina, respectively, and were identified as 20:2(5,11), 20:2(7,13), 20:3(5,11,14), 22:2(7,13), and 22:2(7,15). In B. meandrina, minor amounts of 24:0, 24:1, 25:0, 26:0, 24:4n-3, 26:3(5,9,19), and 28:3(5,9,19) were found, suggesting sponge biofouling on some bryozoan colonies. Aldehydes (branched saturated and unsaturated C_16–19 homologues) did not exceed 10.3 and 1.9% of the total FAs in D. flustroides and B. meandrina, respectively. The presence of the FA markers that are characteristic of microalgae, protozoans, and detritus in bryozoan lipids agrees well with data on polytrophic feeding of these bryozoans.     

Sensitivity to alcohol in mice with an altered brain fatty acid composition

Ethanol-induced sleep onset times, sleep times and blood alcohol levels upon awakening were measured in mice fed an essential fatty acid deficient, Purina Chow or unsaturated fat diet for nine months. These values in animals fed the essential fatty acid deficient and Purina Chow diets did not differ, but mice fed the unsaturated fat diet had longer sleep times and lower blood alcohol levels upon awakening than mice fed essential fatty acid deficient or Purina Chow diets. Crude brain mitochondrial fractions isolated from mice fed the essential fatty acid deficient diet had decreased levels of docosahexaenoic [22:6(n-3)] and increased levels of eicosatrienoic [20:3(n-9)], docosatrienoic [22:3(n-9)] and docosapentaenoic [22:5(n-6)] acids compared to mice fed the Purina Chow diet. The unsaturated fat diet decreased 22:6(n-3) and increased 22:5(n-6) compared to the Purina Chow dietary regimen. The longer sleep times and lower blood alcohol levels found in mice fed the unsaturated fat diet probably resulted from an artifact due to the obesity of the mice fed this diet and from the hinderance of obesity to the righting reflex (our measure of ethanol potency). We conclude that the alteration of several polyunsaturated fatty acid components in the brain has little or no influence on the sensitivity of the nervous system to alcohol.     

Plasma non-esterified fatty acids of elasmobranchs: comparisons of temperate and tropical species and effects of environmental salinity.

We investigated the influence of environments with different average temperatures and different salinities on plasma NEFA in elasmobranchs by comparing species from tropical vs. cold temperate marine waters, and tropical freshwater vs. tropical marine waters. The influence of the environment on plasma NEFA is significant, especially with regard to essential fatty acids (EFA) and the n-3/n-6 ratio. n-3/n-6 ratios in tropical marine elasmobranchs were lower by two-fold or more compared with temperate marine elasmobranchs, because of higher levels of arachidonic acid (AA, 20:4n-6) and docosatetraenoic acid (22:4n-6), and less docosahexaenoic acid (DHA, 22:6n-3), in the tropical species. These results are similar to those in earlier studies on lipids in teleosts. n-3/n-6 ratios and levels of EFA were similar between tropical freshwater and tropical marine elasmobranchs. This suggests that the observation in temperate waters that marine fishes have higher levels of n-3 fatty acids and n-3/n-6 ratios than freshwater fishes may not hold true in tropical waters, at least in elasmobranchs. It also suggests that plasma NEFA are little affected by freshwater vs. seawater adaptation in elasmobranchs. Likewise, we found that plasma NEFA composition and levels were not markedly affected by salinity acclimation (2 weeks) in the euryhaline stingray Himantura signifer. However, in contrast to our comparisons of freshwater-adapted vs. marine species, the level of n-3 fatty acids and the n-3/n-6 ratio were observed to significantly decrease, indicating a potential role of n-3 fatty acids in salinity acclimation in H. signifer.     

Plasma non-esterified fatty acids of elasmobranchs: comparisons of temperate and tropical species and effects of environmental salinity

We investigated the influence of environments with different average temperatures and different salinities on plasma NEFA in elasmobranchs by comparing species from tropical vs. cold temperate marine waters, and tropical freshwater vs. tropical marine waters. The influence of the environment on plasma NEFA is significant, especially with regard to essential fatty acids (EFA) and the n-3/n-6 ratio. n-3/n-6 ratios in tropical marine elasmobranchs were lower by two-fold or more compared with temperate marine elasmobranchs, because of higher levels of arachidonic acid (AA, 20:4n-6) and docosatetraenoic acid (22:4n-6), and less docosahexaenoic acid (DHA, 22:6n-3), in the tropical species. These results are similar to those in earlier studies on lipids in teleosts. n-3/n-6 ratios and levels of EFA were similar between tropical freshwater and tropical marine elasmobranchs. This suggests that the observation in temperate waters that marine fishes have higher levels of n-3 fatty acids and n-3/n-6 ratios than freshwater fishes may not hold true in tropical waters, at least in elasmobranchs. It also suggests that plasma NEFA are little affected by freshwater vs. seawater adaptation in elasmobranchs. Likewise, we found that plasma NEFA composition and levels were not markedly affected by salinity acclimation (2 weeks) in the euryhaline stingray Himantura signifer. However, in contrast to our comparisons of freshwater-adapted vs. marine species, the level of n-3 fatty acids and the n-3/n-6 ratio were observed to significantly decrease, indicating a potential role of n-3 fatty acids in salinity acclimation in H. signifer.     

The effect of dietary fish oils on eicosanoid biosynthesis in peritoneal macrophages is influenced by both dietary N-6 polyunsaturated fats and total dietary fat

Recent research has implicated dietary fish oils in the reduction of eicosanoids formed from arachidonic acid and amelioration of chronic diseases such as coronary heart disease, atherosclerosis and inflammation. Feeding studies were conducted to determine if the efficacy of dietary n-3 polyunsaturated fatty acids (PUFA) from fish oils was influenced by the quantity of n-6 polyunsaturated fatty acids and the total level of fat in the diet. Groups of mice were fed diets composed of 5 and 20% total fat with varying proportions of linoleic acid as a source of n-6 PUFA. Menhaden oil as a source of n-3 PUFA was fed at two levels of n-6 at each level of total fat. Eicosanoid biosynthesis was stimulated and assayed in the mouse peritoneum using zymosan as an inflammatory stimulus. Production of LTE4 and PGE2 was enhanced by increasing n-6 PUFA in the diet at both levels of total fat. High dietary fat significantly suppressed leukotriene (LT) synthesis. Dietary menhaden oil reduced LTE4 and PGE2 synthesis at both levels of dietary n-6 in the low fat study. In animals on 20% dietary fat menhaden oil significantly reduced LT synthesis only at a relatively low dietary n-6 PUFA. On a high n-6 PUFA high fat diets, menhaden oil did not significant affect LTE4 synthesis in response to zymosan stimulation. The results suggest that the effectiveness of fish oils in reducing eicosanoids in response to specific stimulation is influenced by the level of n-6 and the total quantity of fat in the diet.     

Microalgae for use in tropical aquaculture I: Gross chemical and fatty acid composition of twelve species of microalgae from the Northern Territory,Australia

Twelve species of microalgae, isolated from north Australian marine, freshwater and hypersaline environments, were grown under controlled conditions of temperature, pH, photon flux density and salinity, and analysed for ash, total protein, water soluble carbohydrates, chlorophylla, total lipids, total fatty acids and fatty acid composition. Highest levels of the polyunsaturated fatty acid eicosapentaenoic acid [20:5(n-3)] were found in the marine diatoms.Nitzschia (frustulum) andN. closterium (23.1% and 15.2% of total fatty acids, respectively). None of the species studied had levels of docosahexaenoic acid [22:6(n-3)] greater than 1.1 % of total fatty acids. None of the chlorophyte species contained significant levels of either 20:5(n-3) or 22:6(n-3). The highest total fatty acid concentration of all species in the study was found in the freshwater chlorophyte speciesScenedesmus dimorphus (105 mg g^–1 dry wt). The hypersaline speciesDunaliella salina had the highest total lipid content (28.1% dry wt), followed byN. closterium, N. (frustulum) andNavicula sp. (24.2–27.8% dry wt).Chlamydomonas sp. had the highest protein content (66.9% dry wt).N. (frustulum) was highlighted as a possible useful source of lipids and polyunsaturated fatty acids in mixed microalgal diets for mariculture organisms used in tropical aquaculture.Author for correspondence     

Adrenic acid Δ4 desaturation and fatty acid composition in the liver of marine-oil fed streptozotocin diabetic rats

The aim of the present study was to assess the effect of streptozotocin diabetes and insulin treatment on adrenic acid Δ4 desaturation and fatty acid composition of liver microsomes in Wistar rats fed a fat free semi-synthetic basal diet supplemented with 10% EPA-rich marine oil. Results showed that, in liver microsomes of hyperglycemic rats, the 22:6n-3/22:5n-3 ratio in total lipids was elevated and desaturation of adrenic acid to n-6 docosapentaenoic acid was enhanced. Insulin treatment with 2.0 I.U./100 g body weight⁻¹ twice a day for 3 days resulted in hypoglycemia and suppressed both the increased Δ4 n-6 desaturation and 22:6n-3/22:5n-3 ratio. It is concluded that the Δ4 desaturation enzyme system, which is activated by experimental diabetes, is regulated by mechanisms different from those regulating Δ6 and Δ5 desaturations.     

Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios

Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.     

Variability of fatty acid components of marine and freshwater gastropod species from the littoral zone of the Red Sea,Mediterranean Sea,and Sea of Galilee

Eight marine gastropod species from the littoral zone of the Red and Mediterranean Seas, and four freshwater gastropods from the Sea of Galilee were analysed for their fatty acid composition using TLC (silver nitrate impregnated silica gel) and gas chromatography–mass spectrometry (GC/MS). The major fatty acid components in all twelve samples were polyunsaturated fatty acids (PUFA). The total lipids of the Sea of Galilee species contained considerably more 22:6n-3 (from 10.33% to 12.63%) and 20:5n-3 (up to 2.67%) than those from marine species. The differences among the PUFA in these species appear to be due mainly to different environmental conditions, dietary habits and geographical spreading.     

Fish oil diets alter the phospholipid balance, fatty acid composition, and steroid hormone concentrations in testes of adult pigs

The objective was to determine the effect of long-term dietary supplementation of two types of fish oil on lipid composition and steroidogenesis in adult pig testis. Twenty-four Duroc boars, aged 204.5 ± 9.4 d (body weight 128.1 ± 16.7 kg) received daily 2.5 kg of an iso-caloric basal diet supplemented with: 1) 62 g of hydrogenated animal fat (AF); 2) 60 g of menhaden oil (MO) containing 16% of eicosapentaenoic acid (EPA) and 18% of docosahexaenoic acid (DHA); or 3) 60 g of tuna oil (TO) containing 7% of EPA and 33% of DHA. After these diets were consumed for 7 mo, testicular hormones, phospholipid content, and fatty acid composition of individual phospholipids in testis were determined. Body and reproductive organ weights were not significantly affected by dietary treatments. Testicular tissue from boars fed a TO diet, followed by those receiving MO and AF diets, had the lowest level of phosphatidylethanolamine (TO < MO < AF; P < 0.01) but the highest sphingomyelin (TO > MO > AF; P < 0.01). For each phospholipid, boars fed either the MO or TO diet had increased total omega-3 fatty acids, particularly DHA (P < 0.01), by reciprocal replacement of total omega-6 fatty acids (20:4n-6, 22:5n-6). The MO diet increased EPA more than the other diets. Testicular concentrations of testosterone and estradiol were lower in boars fed a TO diet than a MO diet (P < 0.02). In conclusion, long-term dietary supplementation of fish oil, regardless of the EPA/DHA ratio, modified the fatty acid compositions in testis and affected steroid production of healthy adult boars, which may represent a promising models for future studies on fertility.     

Effects of dietary fatty acids on the respiratory and cardiovascular physiology of fish

In animals, the composition of fatty acids (FAs) in body pools reflects dietary intake. This paper reviews evidence that the manipulation of tissue lipids of farmed fish, by feeding them different natural oils, can have significant effects on their respiratory and cardiovascular physiology. Sturgeon and eels with tissue lipids rich in highly unsaturated FAs of the n-3 series (n-3HUFAs, accumulated from dietary menhaden oil) had significantly lower metabolic rates than fish with tissues rich in saturated FAs (SFAs, from coconut oil), although they grew equally well. In sturgeon, the difference in metabolism influenced tolerance of hypoxia. Degrees of hypoxia that depressed oxygen uptake and spontaneous activity in fish rich in SFAs had no such effects on fish rich in n-3HUFAs. In the isolated sturgeon heart working in vitro, reduced oxygen supply depressed the performance of hearts with lipids rich in SFAs but not that of hearts rich in n-3HUFAs. In salmon fed diets with graded mixtures of menhaden and canola oils, there was no relationship between tissue n-3HUFA content (from menhaden oil) and any measured aspect of swimming performance, but a linear relationship between maximum sustainable swimming speed and muscle oleic acid levels (from canola oil). Such exploratory studies indicate that an animal's responses to its environment may be profoundly affected by the oils and FAs it consumes in its diet.