Dietary saturated, monounsaturated, n-6 and n-3 fatty acids, and cholesterol influence platelet fatty acids in the exclusively formula-fed piglet

The minipig as nonrodent species in toxicology--where are we now?

Over the past 3 decades minipigs have moved from being an obscure alternative to dogs and nonhuman primates to being a standard animal model in regulatory toxicity studies. This article covers the use of minipigs as a model in the context of nonclinical drug safety and provides an overview of the minipig's developmental history and relates minipigs to other animal species commonly used in toxicology; and the minipig's translational power is supported by 43 case studies of marketed drug products covered. Special focus is given to criteria for selecting minipigs in nonclinical programs supporting the development of new medicines; the use of swine in the assessment of food additives, agrochemicals, and pesticides; as well as a regulatory perspective on the use of minipigs in Food and Drug Administration (FDA)-regulated products. This article presents the main points conveyed at a symposium held at the 2010 American College of Toxicology meeting in Baltimore, Maryland.

The comparative roles of polyunsaturated fatty acids in pig neonatal development

The present review focuses on the importance of polyunsaturated fatty acid (PUFA) provision for the normal development of the pig neonate. The review describes first the selected fatty acid composition of a range of porcine tissues including nervous tissues, muscle and adipose tissues, reproductive organs and immune-responsive organs and/or cells. The importance of PUFA to the functioning of the immune system of the neonate is considered briefly and is followed by an in-depth consideration of the sources of PUFA for the neonatal pig. The effects of different categories or specific types of fatty acid (i.e. non-essential, linoleic, α-linolenic, long-chain n-6 and n-3 PUFA) on various indices of pig neonatal growth are reviewed. The importance of n-3 PUFA supply to the fetal and early neonatal pig is underlined and evidence is presented for more attention to be given to the amounts available from maternal sources. Based on the material reviewed, recommendations are made on the dietary intake of PUFA in the gestating pig.

Dietary docosahexaenoic acid ameliorates, but rapeseed oil and safflower oil accelerate renal injury in stroke-prone spontaneously hypertensive rats as compared with soybean oil, which is associated with expression for renal transforming growth factor-beta, fibronectin and renin

We have noted that n-3 fatty acid-rich oils, such as fish oil, perilla oil and flaxseed oil as well as ethyl docosahexaenoate (DHA) prolonged the survival time of stroke-prone spontaneously hypertensive rats (SHRSP) rats by approximately 10% as compared with linoleate (n-6)-rich safflower oil. Rapeseed oil with a relatively low n-6/n-3 ratio unusually shortened the survival time by approximately 40%, suggesting the presence of minor components unfavorable to SHRSP rats. This study examined the effects of dietary oils and DHA on renal injury and gene expression related to renal injury in SHRSP rats. Rats fed rapeseed oil- and safflower oil-supplemented diets developed more severe proteinuria than those fed soybean oil-supplemented diet used as a control, but there were no significant differences in blood pressure. In contrast, the DHA-supplemented diet inhibited the development of proteinuria and suppressed hypertension. The mRNA levels for renal TGF-beta, fibronectin and renin were higher in the rapeseed oil and safflower oil groups after 9 weeks of feeding of the experimental diet than in the soybean oil and DHA groups. The fatty acid composition of kidney phospholipids was markedly affected by these diets. These results indicate that the renal injury observed in the groups fed safflower oil with a high n-6/n-3 ratio and rapeseed oil with presumed minor components is accompanied by increased expression of the TGF-beta, renin and fibronectin genes, and that dietary DHA suppresses renal injury and gene expression as compared with soybean oil.

Positional analysis of triglycerides and phospholipids rich in long-chain polyunsaturated fatty acids

Four sources of long-chain polyunsaturated fatty acids (LCP) differing in their chemical structure (triglycerides or phospholipids) and in their origin (tuna triglycerides, fungal triglycerides, egg phospholipids, and pig brain phospholipids) were analyzed to determine the distribution of the component fatty acids within the molecule. Lipase and phospholipase A2 hydrolysis was performed to obtain 2-monoacylglycerols and lysophospholipids, respectively, which allowed us to determine the distribution of fatty acids between the sn-2 and sn-1,3 positions of triglycerides or between the sn-1 and sn-2 position of phospholipids. Fatty acids in the LCP sources analyzed were not randomly distributed. In tuna triglycerides, half of the total amount of 22:6n-3 was located at the sn-2 position (49.52%). In fungal triglycerides, 16:0 and 18:0 were esterified to the sn-1,3 (92.22% and 91.91%, respectively)18:1 and 18:2 to the sn-2 position (59.77% and 62.62%, respectively), and 45% of 20:3n-6 and only 21.64% of 20:4n-6 were found at the sn-2 position. In the lipid sources containing phospholipids, LCP were mainly esterified to the phosphatidylethanolamine fraction. In egg phospholipids, most of 20:4n-6 (5.50%, sn-2 vs. 0.91%, sn-1) and 22:6n-3 (2.89 vs. 0.28%) were located at the sn-2 position. In pig brain phospholipids, 22:6n-3 was also esterified to the sn-2 (13.20 vs. 0.27%), whereas 20:4n-6 was distributed between the two positions (12.35 vs. 5.86%). These results show a different fatty acid composition and distribution of dietary LCP sources, which may affect the absorption, distribution, and tissue uptake of LCP, and should be taken into account when supplementing infant formulas.

Dietary canola oil alters hematological indices and blood lipids in neonatal piglets fed formula

This study was undertaken to determine the effects of canola oil on platelet characteristics, blood lipids and growth in exclusively formula-fed piglets. Piglets were fed from birth to 10 or 18 d with formula containing 51% energy from fat, with 100% fat as canola or soybean oil; 26% soybean, 59% high oleic acid sunflower and 12% flax oil (canola mimic); or 26% canola (canola blend) or soybean (soybean blend) with high oleic acid sunflower, palm and coconut oil. The canola mimic provided similar carbon chain 16 and 18 fatty acids without the sterol or 20:1 and erucic acid (22:1) of canola oil. The oil blends provided formula resembling infant formulas but with higher 16:0 and lower unsaturated fatty acid levels than in canola or soybean oil. Body weight, weight gain and heart and liver weight were not different after 10 or 18 d feeding canola when compared to soybean oil alone or blended oil formulas. Piglets fed formulas with 100% canola oil had lower platelet counts than piglets fed formula soybean oil or the canola oil mimic. Platelet counts were lower, and platelet distribution width and volume were higher, when formulas with 100% canola or soybean rather than the blended oil formulas were fed. The results show that formula fat composition influences the developing hematological system and that canola oil suppresses the normal developmental increase in platelet count in piglets by a mechanism apparently unrelated to the formula 16:0, 18:1, 18:2(n-6) or 18:3(n-3), or plasma phospholipid 20:4(n-6) or 20:5(n-3).

Plasma and red blood cell fatty acid composition in small for gestational age term infants fed human milk or formula

The purpose of the present study was to evaluate the effects of feeding human milk or milk formula on the fatty acid composition of plasma and red blood cell (RBC) lipids in at term small for gestational age infants (SGA) for the first 3 months of life. One group of infants received a formula with a linoleic:alpha-linolenic acid ratio of 10:1 (MF group). Another group served as control and received their own mother's milk (HM group). Blood samples were taken at birth and at 1 week, 4 weeks, and 3 months of life. Plasma and RBC fatty acid composition were analyzed by gas liquid chromatography and results of total plasma lipids were expressed as concentrations by adding an internal standard. Concentrations of saturated and monounsaturated fatty acids increased in total plasma lipids with age in all infants. In contrast, those fatty acids decreased when results were expressed as percentages of total fatty acids. Long-chain polyunsaturated fatty acids (LCP) decreased regardless of how results were expressed, but the absolute concentrations of these fatty acids in plasma available for tissue accretion were greater than suggested by the percentage results. Plasma and RBC docosahexaenoic acid (22:6n-3) decreased in the MF group in comparison to the HM group. Arachidonic acid (20:4n-6) was lower in plasma of MF-fed infant but not in RBC phospholipids. We conclude that term SGA infants fed an adapted milk formula with a linoleic:alpha-linolenic acid ratio of 10:1 but devoid of LCP may lead to a low n-3 LCP status.

Free fatty acid fractions from some vegetable oils exhibit reduced survival time-shortening activity in stroke-prone spontaneously hypertensive rats

Previously, we demonstrated that several vegetable oils that included low-erucic rapeseed oil markedly shortened the survival time (by approximately 40%) of stroke-prone spontaneously hypertensive (SHRSP) rats as compared with perilla oil, soybean oil, and fish oil. We considered that a factor other than fatty acids is toxic to SHRSP rats, because the survival time-shortening activity could not be accounted for by the fatty acid compositions of these oils. In fact, a free fatty acid (FFA) fraction derived from lipase-treated rapeseed oil was found to be essentially devoid of such activity. A high-oleate safflower oil/safflower oil/perilla oil mixture exhibited a survival time-shortening activity comparable to that of rapeseed oil, but the activity of this mixed oil was also reduced by lipase treatment. A partially hydrogenated soybean oil shortened the survival time by approximately 40%, but a FFA fraction derived from lipase-treated partially hydrogenated soybean oil shortened it by 13% compared with soybean oil. Fatty acid compositions of the rapeseed oil and a FFA fraction derived from lipase-treated rapeseed oil were similar, but those of hepatic phospholipids of rats fed the oil and FFA were slightly but significantly different. These results support the interpretation that the survival time-shortening activity exhibited by some vegetable oils is due to minor components other than fatty acids, and that an active component(s) were produced in or contaminated soybean oil during the partial hydrogenation processes.

Effects of dietary marine oils and olive oil on fatty acid composition, platelet membrane fluidity, platelet responses, and serum lipids in healthy humans

The influence of various dietary marine oils and olive oil on fatty acid composition of serum and platelets and effects on platelets and serum lipids were investigated as part of an extensive study of the effects of these oils on parameters associated with cardiovascular/thrombotic diseases. Healthy volunteers (266) consumed 15 mL/d of cod liver oil (CLO); whale blubber oil (refined or unrefined); mixtures of seal blubber oil and CLO; or olive oil/CLO for 12 wk. In the CLO, seal oil/CLO, and whale oil groups, serum levels of eicosapentaenoic acid (EPA) were increased. In platelets, EPA was increased in the CLO, seal/CLO, and olive oil/CLO groups. The localization of n-3 polyunsaturated fatty acids in the triacylglycerols did not seem to influence their absorption. Intake of oleic acid is poorly reflected in serum and platelets. No significant differences in triacylglycerols (TG), total cholesterol, or high density lipoprotein cholesterol were observed, even though TG were reduced in the CLO, CLO/seal oil, and whale oil groups. Mean platelet volume increased significantly in both whale oil groups and the CLO/olive oil group. Platelet count was significantly reduced in the refined whale oil group only. Lipopolysaccharide-stimulated blood tended to generate less thromboxane B2 in CLO, CLO/seal, and CLO/olive groups. The whale oils tended to reduce in vivo release of beta-thromboglobulin. In conclusion, intake of various marine oils causes changes in platelet membranes that are favorably antithrombotic. The combination of CLO and olive oil may produce better effects than these oils given separately. The changes in platelet function are directly associated with alterations of fatty acid composition in platelet membranes.

Hematological and lipid changes in newborn piglets fed milk-replacer diets containing erucic acid

Canola oil is not presently permitted in infant formulations in the United States because of lack of information concerning the effects of feeding canola oil to the newborn. We have previously reported a transient decrease in platelet counts and an increase in platelet size in newborn piglets fed canola oil for 4 wk, and have confirmed this in the present study. In canola oil-fed piglets, changes in platelet size and number were overcome by adding either long-chain saturated fatty acids from cocoa butter (16:0 and 18:0), or shorter-chain saturates from coconut oil (12:0 and 14:0). Feeding a high erucic acid rape-seed (HEAR) oil, with 20% 22:1n-9, led to an even greater platelet reduction and increased platelet size throughout the 4-wk trial. Bleeding times were longer in piglets fed canola oil or HEAR oil compared to sow-reared and soybean oil-fed piglets. There were no other diet-related changes. Diet-induced platelet changes were not related to platelet lipid class composition, but there were fatty acid changes. The incorporation of 22:1n-9 into platelet phospholipids of piglets fed canola oil was low (0.2-1.2%), and even for the HEAR oil group ranged from only 0.2% in phosphatidylinositol to 2.4% in phosphatidylserine. A much greater change was observed in the concentration of 24:1n-9 and in the 24:1n-9/24:0 ratio in platelet sphingomyelin (SM). The 24:1n-9 increased to 49% in the HEAR oil group compared to about 12% in animals fed the control diets (sow-reared piglets and soybean oil-fed group), while the 24:1n-9/24:0 ratio increased from about 1 to 12. Even feeding canola oil, prepared to contain 2% 22:1n-9, led to a marked increase in 24:1n-9 to 29% and had a 24:1n-9/24:0 ratio of 5. The canola oil/cocoa butter group, which also contained 2% 22:1n-9, showed a lower level of 24:1n-9 (20%) and the 24:1n-9/24:0 ratio (3) compared to the canola oil group. The results suggest that the diet-related platelet changes in newborn piglets may be related to an increase in 24:1n-9 in platelet SM, resulting from chain elongation of 22:1n-9. The inclusion of canola oil as the sole source of fat in the milk-replacer diets of newborn piglets resulted in significant platelet and lipid changes.

The incorporation of dietary n-3 polyunsaturated fatty acids into porcine platelet phospholipids and their effects on platelet thromboxane A2 release

We investigated the dynamic changes in fatty acid (FA) composition in platelet phospholipid (PL) and in the release of thromboxane from stimulated platelets in pigs prefed a diet enriched with polyunsaturated fatty acids (PUFA) of the n-3 and n-6 families of FAs. For 20 days, we fed pigs diets supplemented with either corn oil, fish oil, or fish and borage oil. Platelets were separated from blood drawn at baseline and then on day 4, 8, 12, 16 and 20 of the dietary regimen. Analysis of the FA contained in platelet PL demonstrated that significant changes in PUFA composition occurred during dietary supplementation with fish oil and fish and borage oil. Eicosapentaenoic acid (EPA) from fish oil was rapidly incorporated into PL of platelets and reached a steady-state plateau by day 12. An increase in the content of docosahexaenoic acid (DHA) in the platelets' PL was observed in both groups receiving fish oil. This increase in n-3 PUFA in platelet PL occurred with a concomitant decrease in the content of n-6 FA, primarily of arachidonic acid (AA) in the PL of platelets in both fish oil groups. Dietary supplementation with borage oil, which contains gammalinolenic acid (GLA), increased dihomogammalinolenic acid (DGLA) content in platelet PL. Following A23187 stimulation of platelets, levels of thromboxane B2 (TxB2), the stable metabolite of thromboxane A2 (TxA2), were significantly suppressed in both fish oil groups compared to the corn oil-supplemented group. Dietary supplementation of EPA and EPA plus GLA increased platelet PL content of EPA, and EPA and DGLA, respectively. Following platelet stimulation, TxA2 production was significantly increased, an increase that was attenuated in the platelets from pigs prefed fish oil, and even more so in the fish and borage-oil-prefed pigs.

Hematological and lipid changes in newborn piglets fed milk replacer diets containing vegetable oils with different levels of n-3 fatty acids

To test if linolenic acid (18:3n-3) from vegetable oils would affect bleeding times and platelet counts in newborns, piglets were used as a model fed milk replacer diets containing 25% (by wt) vegetable oils or oil mixtures for 28 d and compared to sow-reared piglets. The oils tested included soybean, canola, olive, high oleic sunflower (HOAS), a canola/coconut mixture and a mixture of oils mimicking canola in fatty acid composition. All piglets fed the milk replacer diets showed normal growth. Bleeding times increased after birth from 4-6 min to 7-10 min by week 4 (P < 0.001), and were higher in pigs fed diets containing 18:3n-3, as well as in sow-reared piglets receiving n-3 polyunsaturated fatty acids (PUFA) in the milk, as compared to diets low in 18:3n-3. Platelet numbers increased within the first week in newborn piglets from 300 to 550 x 10(9)/L, and remained high thereafter. Milk replacer diets, containing vegetable oils, generally showed a transient delay in the rise of platelet numbers, which was partially associated with an increased platelet volume. The oils showed differences in the length of delay, but by the third week of age, all platelet counts were > 500 x 10(9)/L. The delay in rise in platelet counts appeared to be related to the fatty acid composition of the oil, as the effect was reproduced by a mixture of oils with a certain fatty acid profile, and disappeared upon the addition of saturated fatty acids to the vegetable oil. There were no alterations in the coagulation factors due to the dietary oils. Blood plasma, platelets and red blood cell membranes showed increased levels of 18:3n-3 and long-chain n-3 PUFA in response to dietary 18:3n-3. The level of saturated fatty acids in blood lipids was generally lower in canola and HOAS oil-fed piglets as compared to piglets fed soybean oil or reared with the sow. The results suggest that consumption of milk replacer diets containing vegetable oils rich in 18:3n-3 does not represent a bleeding risk, and that the transient lower platelet count can be counterbalanced by the addition of saturated fatty acids to the vegetable oils.