Contrasting effects of low or high copper intake on rat tissue lipid essential fatty acid composition

The effects of low copper intake or copper supplementation on the metabolism of stearic acid have been studied previously, but their effects on essential fatty acids have not been reported. Male Sprague-Dawley rats were fed for 12 weeks on pelleted semi-synthetic diets containing less than 1 mg/kg copper (low copper), 6 mg/kg (copper control), or 250 mg/kg copper (copper supplemented). The fatty acid composition of the total phopholipids and triglycerides of plasma, liver, heart and adipose tissue was analyzed by gas liquid chromatography. In low copper rats compared to controls, palmitic and oleic acids were decreased but stearic acid and docosahexaenoic acid were increased in plasma, liver and heart phopholipids. Arachidonic acid was also increased in plasma and liver phospholipids in low copper rats. In liver triglycerides, linoleic and arachidonic acids were increased but palmitic and oleic acid were decreased in low copper rats. Copper supplementation had the opposite effect; palmitic and oleic acids were increased in phospholipids and triglycerides whereas essential fatty acids were generally decreased. Hence, copper not only has a direct effect on the desaturation of stearic acid but also has significant effects on the tissue lipid composition of essential fatty acids.     

Metabolic effects of dietary stearic acid in mice: changes in the fatty acid composition of triglycerides and phospholipids in various tissues.

The fatty acid patterns of triglycerides and phospholipids extracted from adipose tissue, liver, heart, kidney, spleen, and lung of 3 groups of C57BL/6 mice were determined after feeding diets rich in palmitic acid (16:0) (high palmitic: 16:0 = 45.1% of total fatty acids), stearic acid (18:0) (high stearic: 18:0 = 42.9% of total fatty acids) and oleic acid (18:1) (high oleic: 18:1 = 79.7% of total fatty acids) for 9 months. Triglyceride content of adipose, liver, heart, kidney, lung and spleen tissues was significantly enriched in palmitic acid in mice fed the high palmitic diet (range among all tissues: 19.9% +/- 0.2% to 29.0% +/- 1.9% of total fatty acids) and in oleic acid in mice fed the high oleic diet (range 56.0% +/- 1.9% to 71.6% +/- 1.2%). The stearic acid content of organ triglycerides in mice fed the high stearic diet ranged from 3.7% +/- 0.3% to 10.8% +/- 1.2%; however, the content of oleic acid on this diet (range: 57.0% +/- 1.8% to 71.4% +/- 1.7%) was similar to the one observed in mice fed the high oleic diet. In all organs, phospholipids had a significantly higher percentage of stearic acid (range: 23.5% +/- 0.9% to 51.5% +/- 6.6%) than triglycerides, regardless of diet. To evaluate the production of oleate from stearate and palmitate, 2 groups of mice were fed the high palmitic and the high stearic diets for 1 week and then injected intravenously with [1-14C]palmitate and [1-14C]stearate and the amount of labelled oleate in liver triglycerides was measured.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incorporation of deuterium labeled cis- and trans-9-octadecenoic acid in humans: plasma, erythrocyte, and platelet neutral lipids.

Mixtures of specifically deuterated triolein and trielaidin were fed to three subjects, and the incorporation of these labeled fats into human plasma, erythrocyte, and platelet neutral lipids was followed by gas chromatography-mass spectrometry analysis. Plasma triglycerides selectively incorporated 10% more oleic acid than elaidic acid. Plasma cholesterol ester samples contained three times more oleic acid than elaidic acid. Plasma free fatty acid fractions also contained about 25% more elaidic acid than oleic acid. Low levels of deuterated fatty acids were found in the platelet neutral lipids. These samples followed the same general selectivities observed in the plasma samples. Results from analysis of erythrocyte neutral lipids were inconsistent. Erythrocytes from one subject contained high levels of deuterated fat in the triglyceride fraction, whereas erythrocytes from a second subject contained very low levels of deuterated fat. Uptake of elaidic acid by blood lipids confirms selectivities and distribution patterns previously reported in animal and in vitro studies. Effect of the number and position of the deuterium atoms on fatty acid metabolism is evaluated by feeding three differently labeled deuterated elaidic acids and two differently labeled deuterated oleic acids as paired mixtures. A 28% deuterium isotope effect due to deuterium on the fatty acid double bond was observed in the cholesteryl ester samples when oleic-9,10-d₂ acid was fed against oleic-8,8,13,13,14,14-d₆ acid. No evidence for a similar isotope effect was found for deuterated fatty acid incorporation into triglycerides and free fatty acid fractions.     

Lipid content of human and rat pancreas

We analyzed the lipid composition of the human pancreas and performed a parallel study on rat pancreas. Some precautions were taken in order to keep the secretory zymogens as inactive precursors in both tissues. The lipid content of the human pancreas corresponded to 5.5% of the tissue wet weight, lower than that found in pancreas of two-month-old Wistar rats (10%). In man, triglycerides and phospholipids were found at comparable levels, respectively, 37 and 30 mg/g of pancreas wet weight, not far from the values of the rat pancreas. In human pancreas, phosphatidylcholines and lysophosphatidylcholines represented about 40% of the total phospholipid fraction, phosphatidylethanolamines and lysophosphatidylethanolamines 21%, and phosphatidylserines and -inositols were found equally represented with 7.5%. The total cholesterol content accounted for about 4.5% of the total lipids; only 30% was esterified. By comparison, in rat, total cholesterol represented 3.3% of lipids and 90% was esterified. The phospholipids in human pancreas contained high amounts of saturated fatty acids (92%) mainly stearic and palmitic, whereas triglycerides contained equal amounts of saturated and unsaturated fatty acids, principally represented by oleic and palmitic acids. In rats the phospholipids contained only 63% saturated fatty acids (palmitic and stearic) and triglycerides contained 61% unsaturated fatty acids (mainly oleic and linoleic). In terms of lipid composition, there is a greater similarity between human and rat pancreas than with other known pancreas, such as the guinea pig and the ox.     

Adverse physicochemical properties of tripalmitin in beta cells lead to morphological changes and lipotoxicity in vitro

Aims/hypothesis Long-term exposure of beta cells to lipids, particularly saturated fatty acids in vitro, results in cellular dysfunction and apoptosis (lipotoxicity); this could contribute to obesity-related diabetes. Our aims were to relate cell death to intracellular triglyceride concentration, composition and localisation following incubation of INS1 cells in saturated and unsaturated NEFA in high and low glucose concentrations.Materials and methods Insulin-producing INS1 cells were cultured (24 h; 3 and 20 mmol/l glucose) with palmitic, oleic or linoleic acids and the resulting intracellular lipids were analysed by gas chromatography and microscopy. Cell death was determined by quantitative microscopy and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and glucose-stimulated insulin secretion by ELISA.Results All NEFA (0.5 mmol/l, 0.5% albumin) inhibited glucose-stimulated (20 mmol/l) insulin secretion. Cytotoxicity was evident only with palmitic acid (p<0.05), in which case intracellular triglyceride consisted largely of tripalmitin in angular-shaped dilated endoplasmic reticulum. Cytotoxicity and morphological disruption were reduced by addition of unsaturated NEFA. Triglyceride content (control cells; 14.5 ng/g protein) increased up to 10-fold following incubation in NEFA (oleic acid 153.2 ng/g protein; p<0.05) and triglyceride and phospholipid fractions were both enriched with the specific fatty acid added to the medium (p<0.05).Conclusions/interpretation In INS1 cells, palmitic acid is converted in the endoplasmic reticulum to solid tripalmitin (melting point >65°C), which could induce endoplasmic reticulum stress proteins and signal apoptosis; lipid-induced apoptosis would therefore be a consequence of the physicochemical properties of these triglycerides. Since cellular triglycerides composed of single species of fatty acid are not likely to occur in vivo, destruction of beta cells by saturated fatty acids could be predominantly an in vitro scenario.     

Fatty acid composition of liver triglycerides in various stages of fat deposition in the parenchyma

Summary In 30 diabetic inpatients the fatty acid pattern of triglycerides in parenchymal liver cells was studied by gas-liquid chromatography. With increasing size of fat droplets, a significant increase in the proportion of palmitic and oleic acid was observed as well as a significant fall of arachidonic (C 20: 4) and eicosapentaenoic acid (C 20: 5).     

Association of fatty acid profile in plasma lipid fractions with HbA1c in type 2 diabetic patients

The aim of this pilot study has been the comparison of fatty acid profiles of diabetic and healthy subjects in order to evaluate the relationship between fatty acid profiles in plasma lipid fractions and glycated haemoglobin (HbA1c) in type 2 diabetes (T2D) patients. The fatty acid composition of fasting plasma lipid subfractions has been analyzed in patients (n?=?26) diagnosed with T2D and in corresponding control group (n?=?26) of healthy voluntary blood donors. Five subfractions containing phospholipids (PLs), diglycerides (DGs), free fatty acids (FFAs), triglycerides (TGs), and cholesterol esters (CEs) were isolated from plasma samples and separated by thin-layer chromatography. Fatty acid composition of these subfractions was analyzed by GC/FID. Significant changes in fatty acid profiles were found in all lipid fractions from T2D patients in comparison with the control group. HbA1c correlated negatively with delta 9 desaturation (9D) index. Significantly positive correlation of palmitic acid levels and negative correlation of oleic acid levels with HbA1c concentration were found in PL and TG fractions with higher significance in TGs. This pilot study has shown possible associations of HbA1c, common parameter measured in routine laboratories, with lipid metabolism. The strongest correlation was found in plasma TGs, especially in case of palmitic and oleic acids. This is the first report showing that metabolic control assessed by HbA1c is negatively associated with delta 9D index.     

Changes in individual plasma free fatty acids in obese females during fasting and refeeding

In order to determine whether the metabolism of individual free fatty acids is affected by fasting, plasma levels were measured daily in seven obese females during ten days of fasting and four days of refeeding. There was a gradual rise in free fatty acids throughout the fasting period with some variability during the last three days. Free fatty acids remained high during early refeeding followed by a decrease at the end of refeeding. Changes in concentration were most pronounced for oleic (18:1w9) and palmitic (16:0) acids which had the highest initial levels. Expressed as percent change from baseline, oleic, palmitic, and linoleic (18:2w6) acids had similar patterns, while changes were more dramatic for palmitoleic acid (16:1) and less so for stearic acid (18:0) than the others. When expressed as proportion of total free fatty acids, there was very little change in any individual free fatty acid despite the large fluctuations in actual plasma values. It appears that the five major free fatty acids in plasma undergo similar changes during fasting and refeeding, and the palmitic and oleic acids can serve as suitable tracers for metabolic studies.     

Polyunsaturated fatty acids reduce non-receptor-mediated transcellular permeation of protein across a model of intestinal epithelium in vitro

BACKGROUND: Dietary polyunsaturated fatty acids influence the natural history of intestinal inflammatory diseases. Varying the types of long-chain fatty acids that are exposed to cells alters the physicochemical properties of cell membranes. This study aimed to determine whether such variations alter transcellular and paracellular permeability in intestinal epithelium. METHODS: Monolayers of Caco-2 cells, allowed to differentiate by culturing for 7 days following confluence, were used as the model for intestinal epithelium. Paracellular permeability was assessed by measurement of transepithelial resistance, while transcellular permeability was assessed by the transepithelial flux of horseradish peroxidase. RESULTS: Exposure of the cells to 100 micromol/L of palmitic acid, oleic acid, eicosapentaenoic acid, or linoleic acid, was not toxic to cells (measured by leakage of lactate dehydrogenase), and altered cell membrane fatty acid composition (as measured by gas chromatography). Flux of horseradish peroxidase was significantly affected by 24 h fatty acid exposure (P= 0.038, ANOVA), being decreased by 23 +/- 6% (mean +/- SEM) by eicosapentaenoic acid and 25 +/- 3% by linoleic acid. Oleic acid, palmitic acid and butyrate, had no effect. Transepithelial resistance also varied significantly across the treatment groups (P< 0.001) due to a 28 +/- 5% increase induced by butyrate. The long-chain fatty acids had no effect. CONCLUSIONS: Both omega-3 and omega-6 polyunsaturated fatty acids reduce transcellular, non-receptor-mediated permeation of proteins across differentiated Caco2 cell monolayers, without altering paracellular permeability. Alteration of intestinal barrier function should be considered as a possible mechanism of action of dietary polyunsaturated fatty acids.     

Effect of dietary elaidic versus vaccenic acid on blood and liver lipids in the hamster.

Male hamsters (30 per group) were fed five different semi-purified diets ad libitum. The diets, containing 30% of energy (en%) as fat, differed in their dietary fat composition (specified fatty acids exchanged at 10 en%) and were fed for 4 weeks. The five fatty acids compared in mixed triglycerides were elaidic acid (C18:1 9t), vaccenic acid (C18:1 11t), their cis-counterpart oleic acid (C18:1 9c), medium-chain fatty acids (MCFA; C8:0 and C10:0), and palmitic acid (C16:0). Compared with oleic acid, dietary MCFA and palmitic acid tended to increase blood cholesterol levels in the hamsters. The effect of elaidic and vaccenic acid on blood cholesterol did not differ from that of oleic acid. When elaidic acid and vaccenic acids were compared directly, the ratio of LDL/HDL-cholesterol in plasma was significantly higher in hamsters fed vaccenic acid than in those fed elaidic acid, and elaidic acid was incorporated at low levels, but more efficiently than vaccenic acid at the sn-2 position of platelet phospholipids. Biological consequences of this low incorporation are considered unlikely as levels of arachidonic acid (C20:4 n-6) and docosohexaenoic acid (C22:6 n-3) in the platelet phospholipids of all dietary groups did not differ. With respect to the effect on the LDL/HDL-cholesterol ratio, elaidic acid may be preferable to vaccenic acid. We conclude that this animal study does not provide evidence for the suggestion, based on epidemiological observations, that elaidic acid would be more detrimental to cardiovascular risk than vaccenic acid.     

POSSIBLE RELATIONSHIP BETWEEN ALTERED FATTY ACID COMPOSITION OF SERUM,PLATELETS, AND AORTA AND HYPERTENSION INDUCED BY SUGAR FEEDING IN RATS

To establish a relationship between alterations in fatty acid metabolism, induced by sugar ingestion, and hypertension, we analyzed fatty acid composition of serum, platelets and aorta in rats which had 30% of sugar in their drinking water for 18–20 weeks, and became hypertensive, hypertriglyceridemic and hyperinsulinemic. The fatty acid composition in sugar-fed as compared with that from control rats was as follows: in serum phospholipids, triglycerides and cholesterol ester fractions, palmitic, palmitoleic, oleic and cis-11-eicosadecaenoic acids were present in a higher proportion. In serum phospholipid fraction linoleic and arachidonic acids were decreased and a significant increase was observed in the proportion of dihomo-γ-linolenic acid. In the membrane phospholipids of platelets and aorta, higher proportions of palmitoleic and of oleic acids were observed. Differences in fatty acid composition of phospholipids between sugar-fed and control rats are consistent with altered membrane fluidity. Altered membrane function is a potential mechanism involved hypertension in rats.in sugar-induced     

Possible relationship between altered fatty acid composition of serum, platelets, and aorta and hypertension induced by sugar feeding in rats

To establish a relationship between alterations in fatty acid metabolism, induced by sugar ingestion, and hypertension, we analyzed fatty acid composition of serum, platelets and aorta in rats which had 30% of sugar in their drinking water for 18-20 weeks, and became hypertensive, hypertriglyceridemic and hyperinsulinemic. The fatty acid composition in sugar-fed as compared with that from control rats was as follows: in serum phospholipids, triglycerides and cholesterol ester fractions, palmitic, palmitoleic, oleic and cis-11-eicosadecaenoic acids were present in a higher proportion. In serum phospholipid fraction linoleic and arachidonic acids were decreased and a significant increase was observed in the proportion of dihomo-gamma-linolenic acid. In the membrane phospholipids of platelets and aorta, higher proportions of palmitoleic and of oleic acids were observed. Differences in fatty acid composition of phospholipids between sugar-fed and control rats are consistent with altered membrane fluidity. Altered membrane function is a potential mechanism involved hypertension in rats in sugar-induced.     

Fatty acid binding protein in kidney of normotensive and genetically hypertensive rats

Fatty acid binding protein was purified from renal medulla, and its binding activity and fatty acid composition were determined in spontaneously hypertensive stroke-prone rats (SHRSP). Wistar-Kyoto rats (WKY) were used as controls. Fatty acid binding activity was higher in 5-week-old prehypertensive SHRSP than in control WKY (0.155 +/- 0.006 vs 0.030 +/- 0.001 mol palmitic acid/mol protein). However, in 40-week-old rats, the activity was decreased only in SHRSP with established hypertension (0.035 +/- 0.002 vs 0.028 +/- 0.003 mol palmitic acid/mol protein WKY). Fatty acid compositions were similar among 5-week-old and 40-week-old control WKY and 5-week-old SHRSP (palmitic acid, 24%; stearic acid, 14%; oleic acid, 30%; linoleic acid, 29%; arachidonic acid, 3%), although the total amount of bound long-chain fatty acids was decreased in 5-week-old SHRSP, explaining the high fatty acid binding activity in this preparation. Fatty acid binding protein from 40-week-old SHRSP had an elevated proportion of endogenous arachidonic acid, with other fatty acids being relatively reduced (palmitic acid, 8%; stearic acid, 2%; oleic acid, 4%; linoleic acid, 10%; arachidonic acid, 76%), indicating increased arachidonic acid transport in the cytosol. These results show that genetically hypertensive rats had an alteration in fatty acid transport mediated by fatty acid binding protein; this alteration may be involved in the pathogenesis of hypertension.     

Lipid composition and fatty acid analysis ofHelicobacter pylori

Lipids extracted fromHelicobacter pylori were separated into lipid classes by thin-layer chromatography. SimpleH. pylori lipids consisted of cholesterol esters, triglycerides, free fatty acids, cholesterol, diacylglycerols, and monoacylglycerols. Fatty acids were released from each lipid class by acid methanolysis, and analyzed by gas liquid chromatography and mass spectrometry. Unique methoxy fatty acids, including 11-methoxy heptadecanoic and 11-methoxy nonadecanoic acids, were the major components of the cholesterol esters and triglycerides. The predominance of methoxy fatty acids in the cholesterol esters ofH. pylori may contribute to the acid-resistant characteristic of this bacillus.     

Differential effect of oleic and palmitic acid on lipid accumulation and apoptosis in cultured hepatocytes

Background and Aim:  Studies have shown monounsaturated oleic acid to be less toxic than palmitic acid and to prevent/attenuate palmitic acid hepatocites toxicity in steatosis models in vitro . However, to what degree these effects are mediated by steatosis extent is unknown.
Methods:  We evaluated whether steatosis per se is associated with hepatocytes apoptosis and determined the role of oleic and palmitic acid, the most abundant fatty acids in western diets, on triglyceride accumulation and apoptosis in an in vitro model of steatosis induced in three hepatocytic cell lines (HepG2, HuH7, WRL68). The impact of incubation for 24 h with oleic (0.66 and 1.32 mM) and palmitic acid (0.33 and 0.66 mM), alone or combined (molar ratio 2 : 1) on steatosis, apoptosis, and insulin signalling, was evaluated.
Results:  Concurrent with PPARγ and SREBP-1 gene activation, steatosis extent was larger when cells were treated with oleic than with palmitic acid; the latter fatty acid was associated with increased PPARα expression. Cell apoptosis was inversely proportional to steatosis deposition. Moreover, palmitic, but not oleic acid, impaired insulin signalling. Despite the higher amount of fat resulting from incubation of the two fatty acids combined, the apoptosis rate and impaired insulin signalling were lower than in cells treated with palmitic acid alone, indicating a protective effect of oleic acid.
Conclusions:  Oleic acid is more steatogenic but less apoptotic than palmitic acid in hepatocityc cell cultures. These data may provide a biological basis for clinical findings on dietary patterns and pathogenetic models of nonalcoholic fatty liver disease.     

Long-chain fatty acids activate calcium channels in ventricular myocytes.

Nonesterified fatty acids accumulate at sites of tissue injury and necrosis. In cardiac tissue the concentrations of oleic acid, arachidonic acid, leukotrienes, and other fatty acids increase greatly during ischemia due to receptor or nonreceptor-mediated activation of phospholipases and/or diminished reacylation. In ischemic myocardium, the time course of increase in fatty acids and tissue calcium closely parallels irreversible cardiac damage. We postulated that fatty acids released from membrane phospholipids may be involved in the increase of intracellular calcium. We report here that low concentrations (3-30 microM) of each long-chain unsaturated (oleic, linoleic, linolenic, and arachidonic) and saturated (palmitic, stearic, and arachidic) fatty acid tested induced multifold increases in voltage-dependent calcium currents (ICa) in cardiac myocytes. In contrast, neither short-chain fatty acids (less than 12 carbons) or fatty acid esters (oleic and palmitic methyl esters) had any effect on ICa, indicating that activation of calcium channels depended on chain length and required a free carboxyl group. Inhibition of protein kinases C and A, G proteins, eicosanoid production, or nonenzymatic oxidation did not block the fatty acid-induced increase in ICa. Thus, long-chain fatty acids appear to directly activate ICa, possibly by acting at some lipid sites near the channels or directly on the channel protein itself. We suggest that the combined effects of fatty acids released during ischemia on ICa may contribute to ischemia-induced pathogenic events on the heart that involve calcium, such as arrhythmias, conduction disturbances, and myocardial damage due to cytotoxic calcium overload.     

Fatty acid metabolism in primary hyperlipoproteinemia (HLP) (author's transl)

The fatty acid spectra of cholesterol ester and triglyceride fractions separated by thin-layer chromatography were analyzed by gas chromatography in the sera of 252 patients with primary HLP (with 53 cases of type IIa, 48 cases of type IIb, and 151 cases of type IV) and 60 healthy persons. Showing significantly increased values in the cholesterol ester fraction for HLP of types IIa and IIb as well as in the triglyceride fraction for HLP of types IIb and IV were palmitic acid, stearic acid, palmitoleic acid, oleic acid, and eicosatrienic acid. Significantly reduced percentages were obtained for linoleic acid, linolenic acid, arachidonic acid, and eicosapentaenic acid in the same fractions for these types. Possible causes include disturbances of the fatty acid metabolism in the liver, increased selective reesterification of fatty acids of the lipolytic process, and partially altered LCAT activity.     

Effect of acute hypobaric hypoxia on fatty acid metabolism in rat lung

Exposure of male albino rats in the weight range of 70-200 g to 25,000 ft of simulated altitude for 6 h at 32 degrees C caused an increase in plasma free fatty acids with decreased oxidation of palmitic acid-1-14C in lung slices of hypoxic rats. The in vivo esterification of palmitic acid-1-14C to form truglycerides, phosphatidylcholine and phosphatidylethanolamine was also low indicating decreased utilization of fatty acids by hypoxic lungs. De novo lipogenesis was observed to decreased to decrease because of decreased fatty acid biosynthesis as judged from acetate---14C incorporation. The specific activities of triglycerides, phosphatidylcholine and free cholesterol were also decreased. The decreased incorporation into phosphatidylcholine affected the incorporation into phosphatidylcholine of alveolar surfactant (2,000 g sediment fraction). The results are discussed in view of possible decreased energy status of hypoxic lungs.     

Gluteal adipose tissue fatty acids and sleep quality parameters in obese adults with OSAS

Purpose

The aim of this study was to examine the relationships between gluteal adipose tissue fatty acids and sleep quality parameters in obese patients with obstructive sleep apnoea syndrome (OSAS).

Methods

Fatty acids were measured by gas chromatography in 63 OSAS patients, and sleep was assessed by polysomnography.

Results

Significant positive correlations were found between total sleep time, sleep efficiency, slow-wave sleep, and fatty acid concentrations (myristic, palmitic, stearic, saturated fatty acids, oleic acid, polyunsaturated fatty acids, and n???6 fatty acids).

Conclusions

The current study revealed associations between certain gluteal adipose tissue fatty acids and sleep quality in obese patients with moderate to severe OSAS.