Liver Lipid Fractions Research Articles

Fatty acids in multiple circulating lipid fractions reflects the composition of liver triglycerides in humans

Fatty acids (e.g. 16:1n-7) and desaturase indices (e.g. stearoyl-CoA desaturase, SCD) in plasma cholesteryl esters (CE) and phospholipids (PL) are used as biomarkers of dietary fat quality and lipid metabolism and are associated with disease outcomes. Endogenously produced circulating fatty acids are believed to reflect composition of the liver, yet little data exist to support such relationship. We investigated associations between circulating fatty acids and fatty acids within the liver. Liver biopsies and blood were collected from n=60 patients with non-alcoholic fatty liver disease. Fatty acids in CE, PL and triglycerides (TG) in plasma and liver were analyzed using gas chromatography. Associations were assessed using Spearman rank correlations. Overall, fatty acids and desaturase indices in plasma PL and TG showed moderate-strong correlations with fatty acids and desaturase indices in corresponding lipid fractions in liver. For plasma CE, 16:1n-7 and SCD were correlated with 16:1n-7 and SCD in liver CE. Noteworthy, fatty acids in plasma CE and PL also showed moderate-strong correlations with fatty acids in liver TG (e.g. r=0.82-0.87 for 16:1n-7 and r=0.77 for SCD). We demonstrate that fatty acids in circulating lipid fractions, including CE, TG and PL, reflects the composition of liver TG in humans, suggesting that circulating fatty acids might be useful biomarkers for the fatty acid composition of the liver. As liver tissue is rarely available in cohort studies, our findings could enhance our understanding of plasma fatty acids as markers of hepatic lipid metabolism and their links to metabolic diseases.

Tissue-Specific Sample Dilution: An Important Parameter to Optimise Prior to Untargeted LC-MS Metabolomics.

When developing a sample preparation protocol for LC–MS untargeted metabolomics of a new sample matrix unfamiliar to the laboratory, selection of a suitable injection concentration is rarely described. Here we developed a simple workflow to address this issue prior to untargeted LC–MS metabolomics using pig adipose tissue and liver tissue. Bi-phasic extraction was performed to enable simultaneous optimisation of parameters for analysis of both lipids and polar extracts. A series of diluted pooled samples were analysed by LC–MS and used to evaluate signal linearity. Suitable injected concentrations were determined based on both the number of reproducible features and linear features. With our laboratory settings, the optimum concentrations of tissue mass to reconstitution solvent of liver and adipose tissue lipid fractions were found to be 125 mg/mL and 7.81 mg/mL respectively, producing 2811 (ESI+) and 4326 (ESI−) linear features from liver, 698 (ESI+) and 498 (ESI−) linear features from adipose tissue. For analysis of the polar fraction of both tissues, 250 mg/mL was suitable, producing 403 (ESI+) and 235 (ESI−) linear features from liver, 114 (ESI+) and 108 (ESI−) linear features from adipose tissue. Incorrect reconstitution volumes resulted in either severe overloading or poor linearity in our lipid data, while too dilute polar fractions resulted in a low number of reproducible features (<50) compared to hundreds of reproducible features from the optimum concentration used. Our study highlights on multiple matrices and multiple extract and chromatography types, the critical importance of determining a suitable injected concentration prior to untargeted LC–MS metabolomics, with the described workflow applicable to any matrix and LC–MS system.

Dietary Glycotoxins Impair Hepatic Lipidemic Profile in Diet-Induced Obese Rats Causing Hepatic Oxidative Stress and Insulin Resistance.

Nonalcoholic fatty liver disease (NAFLD) is caused by excessive liver lipid accumulation, but insulin resistance is specifically associated with impaired lipid saturation, oxidation, and storage (esterification), besides increased de novo lipogenesis. We hypothesized that dietary glycotoxins could impair hepatic lipid metabolism in obesity contributing to lipotoxicity-driven insulin resistance and thus to the onset of nonalcoholic steatohepatitis (NASH). In diet-induced obese rats with methylglyoxal-induced glycation, magnetic resonance spectroscopy, mass spectrometry, and gas chromatography were used to assess liver composition in fatty acyl chains and phospholipids. High-fat diet-induced obesity increased liver lipid fraction and suppressed de novo lipogenesis but did not change fatty acid esterification and saturation or insulin sensitivity. Despite a similar increase in total lipid fraction when supplementing the high-fat diet with dietary glycotoxins, impairment in the suppression of de novo lipogenesis and decreased fatty acid unsaturation and esterification were observed. Moreover, glycotoxins also decreased polyunsaturated cardiolipins and caused oxidative stress, portal inflammation, and insulin resistance in high-fat diet-induced obese rats. Dietary glycated products do not change total lipid levels in the liver of obese rats but dramatically modify the lipidemic profile, leading to oxidative stress, hepatic lipotoxicity, and insulin resistance in obesity and thus contribute to the onset of NASH.

Maternal undernutrition and offspring sex determine birth-weight, postnatal development and meat characteristics in traditional swine breeds

BackgroundThe aim of this study was to determine how maternal undernutrition during pregnancy and offspring birth-weight can affect the postnatal development of offspring under farm conditions, which may lead to consequences in its meat and carcass quality. The current study involved a total of 80 litters from Iberian sows fed a diet fulfilling daily requirements (n = 47; control) or providing 70% daily requirements (n = 33; underfed) from d 38 to d 90 of gestation when fetal tissue development begins. After birth, piglets born live were classified as low birth-weight (LBW; < 1 kg) and normal birth-weight (NBW; ≥1 kg). During the growing phase, 240 control and 230 underfed pigs (50% males and females) distributed by BW category and sex were studied until the slaughter.ResultsAt birth and weaning, there were significant differences in all morphological measures and weight between NBW and LBW piglets as expected (P < 0.0005), but few effects of the gestational feed restriction. During the growing phase, NBW pigs continued with higher weight than LBW pigs on all the days of evaluation (P < 0.05), even though control-LBW-females and LBW-males showed a catch-up growth. However, underfed pigs showed slower growth and higher feed conversion ratio than control pigs (P < 0.0001) at 215 days old. Moreover, the average daily weight gain (ADWG) for the overall period was greater for NBW, male and control pigs than for their LBW, female and underfed pigs (P < 0.0001, P< 0.0005 and P< 0.05, respectively) and NBW pigs were slaughtered at a younger age than LBW pigs (P < 0.0001). After slaughtering, control pigs also had higher carcass yield and backfat depth than underfed pigs (P < 0.0005) and the maternal nutritional effect caused main changes in the polar lipid fraction of liver and loin. The fatty acid composition of loin in control pigs had higher C18:1n-9 and n-3 FA concentrations, as well as lower ∑n-6/∑n-3 ratio, than in underfed pigs (P < 0.005).ConclusionsIn brief, results showed that the effects of maternal nutritional restriction appeared and increased with offspring age, causing worse developmental patterns for underfed pigs than for control pigs.

Antiatherogenic effect of Tiger nut tubers (Cyperus esculentus L.) supplemented diet in apolipoprotein E knockout mice

The present study was carried out to evaluate the physiological effect of tiger nut tubers on lipid metabolism and peroxidation stress in apolipoprotein E knockout (apoE-/-) mice. Six male and five female mice, 6-7 wk old, was fed AIN 93G control diet supplemented with 25 % of whole powder of tiger nut tubers for 11 wk. Measurements were done for plasma, liver, aorta and brain lipid fractions. Peroxidation stress in mice serum and brain, i.e. vitamin E, nitric oxide and TBARS were evaluated and aortic valve lesions area was also determined. The obtained results showed that, type of diet and mice gender did not affect mice growth parameters. Serum and liver lipids were lowered in male mice fed tiger nut diet than that fed the control diet. However, the effect of tiger nut diet on the peroxidation parameters was not prominent. The mice fed on chufa-diet resulted in significant reduction in the aortic arch atherosclerotic lesions in both gender compared to that fed the basal diet. Our results show that tiger nut tubers have antiatherogenic effect and contain a gender dependent factor which regulates lipid metabolism in apoE-/- mice.

Effects of dietary supplementation with detoxified Rhus verniciflua sap on egg production, yolk lipid and intestinal microflora in laying hens

ObjectiveThis study was conducted to investigate the effects of dietary detoxified Rhus verniciflua sap (RVS) on production performance, egg quality, lipid fractions of egg yolk, liver and serum, and the profile of cecal microflora in laying hens.MethodsTwo hundred 52-week-old Hy-Line Brown layers were randomly divided into 4 groups with 5 replicates per group (2 hens per cage, 5 cages per replicate) and were provided with one of 4 experimental diets containing 0%, 0.05%, 0.1%, or 0.2% RVS, for 6 weeks. Due to unequal intervals of RVS doses, the interactive matrix language procedure of the SAS program was used to correct the contrast coefficients of orthogonal polynomials.ResultsThere were no differences in feed intake and egg weight among the groups. Egg production increased (linearly and quadratically, p<0.05) with increasing levels of RVS. Eggshell thickness increased (linear, p<0.05) as the level of RVS in diets increased. The levels of blood cholesterol and activities of glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase were not altered by dietary treatments. Increasing level of RVS increased (linear, p<0.05) the populations of cecal lactic acid bacteria. The content of yolk cholesterol decreased (linear, p< 0.05) with increasing levels of dietary RVS, although there were no significant differences in each lipid fraction of the liver.ConclusionThis study indicates that dietary RVS could improve laying performance and eggshell quality, and affect cecal lactic acid bacteria in a dose-dependent manner.

The effect of dietary fat on fatty acid composition, gene expression and vitamin status in pre-ruminant calves

Dietary saturated (SFA) and unsaturated fatty acids (UFA) alter fatty acid (FA) composition of various tissues, serum, and circulating immune cells. The objective of this study was to examine the effect of dietary SFA and UFA on adipose, liver, serum, polymorphonuclear (PMN) and peripheral blood mononuclear cells’ (PBMC) FA profiles, gene expression of selected inflammatory mediators, and their relation with serum lipid-soluble vitamin in pre-ruminant calves. Twelve Holstein male calves were randomly assigned to one of two treatments. Starting at 3 d of age, six calves received 120mL palm oil/day (SFA), and six calves received 80mL flaxseed oil plus 40mL conjugated linoleic acid/day (UFA). After 50 d, all animals were euthanized and samples were obtained. Fatty acid composition of non-esterified fatty acid (NEFA), neutral lipid (NL), and phospholipids (PL) was analyzed by gas-chromatography. High-performance liquid chromatography was used to detect α-tocopherol and retinol in liver, as well as α-tocopherol, retinol, and β-carotene in serum. In addition, liver and adipose tissue were analyzed for gene expression of interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, interferon-γ, peroxisome proliferator-activated receptor-γ, TNF-α, retinol binding protein-4, and NF-κB. The PBMC were examined for IL-1β, IL-6, TNF-α and intercellular adhesion molecule-1; PMN cells were analyzed for caspase-1, IL-8 receptor, and l-selectin (l-SEL) expression. Data were analyzed using the Proc TTEST of SAS with significance declared at P≤0.05. Results showed that the UFA had greater α-linolenic acid compared to SFA in all three (NEFA, NL, and PL) lipid fractions of liver, adipose and serum, as well as PBMC and PMN. The greater content of α-LA in calves fed UFA resulted in greater eicosapentaenoic acid (EPA) in all three lipid fractions of serum, as well as NL and PL in adipose tissue. The UFA however, had lower γ-linolenic acid compared with SFA in all three lipid fractions of liver, as well as NL and PL in serum. Dietary UFA also increased total PUFA in all lipid fractions of serum and adipose. In addition, PBMC and PMN had greater EPA in calves fed UFA. Lipid-soluble vitamins in serum were reduced by dietary UFA. In contrast, UFA resulted in upregulation of l-SEL expression in PMN. This may indicate that UFA elevated the substrate for PUFA biosynthesis, but possibly degraded lipid-soluble vitamins to protect these FA from oxidation. Greater circulating PUFA may influence the migration of PMN from the blood to tissues, affecting overall inflammatory responses.

Pharmacological analysis of changes in the contentof diene conjugation, methyl esters of fatty acids of liver lipid fractions by cholinotropic agents during the overcooling of rats

The analysis of changes in the content of diene conjugation, fatty acid methyl esters (FAME) C20 of total lipids, fractions of free fatty acids (FFA) in the liver of animals exposed to overcooling for 3 hours and for 5 days after administration of cholinergic agents has been made. The obtained results indicate changing in the content of methyl esters of fatty acids and diene conjugation of FFA fractions after administration of pharmacological agents as neostigmine, pilocarpine, and atropine to animals on the background of cooling. Changes in the content of diene conjugation coincide with changes in the content of fatty acids (FA) C20 : 4 Δ-5,8,11,14 eicosatetraenoic acids (FA Arakhia) when pilocarpine or atropine was used. The presence of reciprocity was revealed. Basing the reciprocity factor, it was suggested that there was a possible effect of muscarine-sensitive structures of the plasmic membrane hepatocytes on the link between the content of FAME C20 Arakhia, phospholipase A2 activity and the change in the content of diene conjugation in fraction of liver FFA. A possible effect of cholinotropic agents on phospholipase A2 activity in the period of animal cooling was suggested.

Clinical efficasy of L-arginine and ursodeoxycholic acid in the complex treatment of rosacea

Under clinical observation were 77 patients suffered from different clinical forms of acne rosacea that using L-arginin and Ursodeoxycholic acid had treated All patients have functional and organic disturbances of hepatobiliary system before treatment. Complex treatment including L-arginin and Ursodeoxycholic acid led to improvement of balance of liver enzymes and lipid fractions in peripheric blood of investigated patients.

Changes in liver lipidomics associated with sodium cholate-induced liver injury and its prevention by boiogito, a Japanese herbal medicine, in mice

Aim Bile acids play a crucial role in the development of cholestatic liver disease by mediating parenchymal cell injury and inflammation in the liver. Bile acids can also modulate lipid metabolism, although their role in the pathogenesis of cholestatic liver diseases is mostly unknown. We examined the effects of boiogito (BOT), a Japanese herbal medicine, on liver injury and lipid profile in liver lipid fractions in a mouse model of sodium cholate (CA)-induced cholestasis. Methods Lipidomics was carried out to determine the fatty acid composition in liver triglycerides, cholesterol esters, and total phospholipids using gas–liquid chromatography. Results CA induced liver injury and differential changes in fatty acid profile in triglycerides, cholesterol esters, and total phospholipids in the liver. The co-administration of BOT and CA attenuated liver injury and the changes in fatty acid profile in the liver triglycerides but not those in the liver cholesterol esters and total phospholipids. Conclusion Lipidomics indicated a unique property of liver triglyceride fatty acids in association with the preventive effect of BOT against CA-induced liver injury in mice. BOT plays an important role in hepatic TG metabolism via the prevention of cholestasis.

Adipose tissue stearoyl-CoA desaturase 1 index is increased and linoleic acid is decreased in obesity-prone rats fed a high-fat diet

BackgroundFatty acid (FA) composition and desaturase indices are associated with obesity and related metabolic conditions. However, it is unclear to what extent desaturase activity in different lipid fractions contribute to obesity susceptibility. Our aim was to test whether desaturase activity and FA composition are linked to an obese phenotype in rats that are either obesity prone (OP) or resistant (OR) on a high-fat diet (HFD).MethodsTwo groups of Sprague–Dawley rats were given ad libitum (AL-HFD) or calorically restricted (HFD-paired; pair fed to calories consumed by chow-fed rats) access to a HFD. The AL-HFD group was categorized into OP and OR sub-groups based on weight gain over 5 weeks. Five different lipid fractions were examined in OP and OR rats with regard to proportions of essential and very long-chain polyunsaturated FAs: linoleic acid (LA), alpha-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and the stearoyl-CoA desaturase 1 (SCD-1) product 16:1n-7. FA ratios were used to estimate activities of the delta-5-desaturase (20:4n-6/20:3n-6), delta-6-desaturase (18:3n-6/18:2n-6), stearoyl-CoA desaturase 1 (SCD-1; 16:1n-7/16:0, SCD-16 and 18:1n-9/18:0, SCD-18), de novo lipogenesis (16:0/18:2n-6) and FA elongation (18:0/16:0). Fasting insulin, glucose, adiponectin and leptin concentrations were measured in plasma.ResultsAfter AL-HFD access, OP rats had a significantly higher SCD-16 index and 16:1n-7 proportion, but a significantly lower LA proportion, in subcutaneous adipose tissue (SAT) triacylglycerols, as well as significantly higher insulin and leptin concentrations, compared with OR rats. No differences were found between the two phenotypes in liver (phospholipids; triacylglycerols) or plasma (cholesterol esters; phospholipids) lipid fractions or for plasma glucose or adiponectin concentrations. For the desaturase indices of the HFD-paired rats, the only significant differences compared with the OP or OR rats were higher SCD-16 and SCD-18 indices in SAT triacylglycerols in OP compared with HFD-paired rats.ConclusionThe higher SCD-16 may reflect higher SCD-1 activity in SAT, which in combination with lower LA proportions may reflect higher insulin resistance and changes in SAT independent of other lipid fractions. Whether a lower SCD-16 index protects against diet-induced obesity is an interesting possibility that warrants further investigation.

Studies on the kinetics, metabolism and re-utilisation after intra-articular administration of hyaluronan to rabbits.

The pharmacokinetics of hyaluronan (HA) (CAS 9004-61-9) was measured after intra-articular (i.a.) injection of 1 mg/kg of 14C-glucose-labelled HA (14C-HA) (i.e. 2,000 kDa) into the knee joint cavity of rabbits. The movement of HA from the cavity into the systemic circulation was assessed by measuring its concentration in blood and its residue in the cavity. I.a. HA moved into, and disappeared from, the bloodstream at a first-order rate. Synovial fluid, synovial membrane and articular cartilage specimens were taken 24 and 72 h post-injection, and the molecular weight (MW) of HA fractions were measured by using gel filtration chromatography (GFC) using radioactive fractions of known molecular sizes (i.e. 2,000 kDa, 300 kDa and 50 kDa). The radioactivity distribution of synovial fluid had a peak at a 2,000 kDa-equivalent fraction at both 24 and 72 h post-injection, while synovial membrane had a peak at a 300 kDa-equivalent fraction 24 h post-injection and at a 50 kDa-equivalent fraction 72 h post-injection. The radioactivity distribution pattern of articular cartilage showed peaks corresponding to 2,000-300 kDa 24 h post-injection and to 50 kDa 72 h post-injection. The in vivo re-utilisation of i.a. HA was investigated by assessing radioactivity in the acid-soluble, lipid and protein fractions of plasma, blood cells and liver 72 h post-injection. Results show that HA was broken down into C1 units (carbon cycle) before being re-used as an in vivo constituent in the body.

Metabolic rate and tissue reserves in gilthead sea bream (Sparus aurata) under thermal fluctuations and fasting and their capacity for recovery

To differentiate between cold and fasting effects on gilthead sea bream (Sparus aurata) physiology, three conditions (cold-induced fasting at 8 °C, cold group; forced fasting at 18 °C, fasting group, and cyclic thermal fluctuations between 16 °C and 8 °C, fluctuating group) were compared with a control group (feeding at 18 °C). Oxygen consumption rate, plasma lipid fractions, and tissue composition were analysed either during long exposure (5 weeks) or after 20 days of recovery. Sea bream showed strict thermoconformism in metabolic rate and feeding, and all groups, after changes, mobilised perivisceral fat. The fasting group also consumed other tissue reserves sequentially, except nonpolar lipids in liver. In the cold group, this liver lipid fraction increased twofold, but in the fluctuating group, food intake was gradually restored during each short period of higher temperature, and the steatotic livers caused by cold were not seen. During recovery, the fasting group showed the highest growth rate and deposition of reserves, whereas the cold group, although they mobilised liver lipid, did not grow. Appropriate management of the transient short periods of higher temperature may improve recovery from the cold season in gilthead sea bream culture.

Upregulated liver conversion of α-linolenic acid to docosahexaenoic acid in rats on a 15 week n-3 PUFA-deficient diet

We quantified incorporation rates of plasma-derived alpha-linolenic acid (alpha-LNA, 18:3n-3) into "stable" liver lipids and the conversion rate of alpha-LNA to docosahexaenoic acid (DHA, 22:6n-3) in male rats fed, after weaning, an n-3 PUFA-adequate diet (4.6% alpha-LNA, no DHA) or an n-3 PUFA-deficient diet (0.2% alpha-LNA, no DHA) for 15 weeks. Unanesthetized rats were infused intravenously with [1-14C]alpha-LNA, and arterial plasma was sampled until the liver was microwaved at 5 min. Unlabeled alpha-LNA and DHA concentrations in arterial plasma and liver were reduced >90% by deprivation, whereas unlabeled arachidonic acid (20:4n-6) and docosapentaenoic acid (22:5n-6) concentrations were increased. Deprivation did not change alpha-LNA incorporation coefficients into stable liver lipids but increased synthesis-incorporation coefficients of DHA from alpha-LNA by 6.6-, 8.4-, and 2.3-fold in triacylglycerol, phospholipid, and cholesteryl ester, respectively. Assuming that synthesized-incorporated DHA eventually would be secreted within lipoproteins, calculated liver DHA secretion rates equaled 2.19 and 0.82 micromol/day in the n-3 PUFA-adequate and -deprived rats, respectively. These rates exceed the published rates of brain DHA consumption by 6- and 10-fold, respectively, and should be sufficient to maintain normal and reduced brain DHA concentrations, respectively, in the two dietary conditions.

Effects of 3-thia fatty acids on expression of some lipid related genes in Atlantic salmon ( Salmo salar L.)

In this study, the effects of in vivo administration of 3-thia fatty acids (FAs) on lipid metabolism in muscle and liver of Atlantic salmon were investigated. Prior to analysis, the fish were kept in tanks supplied with 5 °C seawater for 20 weeks. The fish were fed fish meal and fish oil (FO)-based diets supplemented with either nothing (FO), or 0.3% and 0.6% of the 3-thia FAs dodecylthioacetic acid (DTA) and tetradecylthioacetic acid (TTA) respectively. The fish grew from an initial weight of 110 g to 220 g in the FO group and to approximately 160 g in the 3-thia FA groups. There was a significant higher mortality (66%) in fish fed 0.6% TTA than in fish fed the 0.3% DTA (15%) and FO diets (15%). None of the 3-thia FA diets affected the lipid content of the salmon muscle. The liver index, however, was significantly higher and the total liver fat content lower in the TTA group than in the FO group. Both DTA and TTA were incorporated into the lipid fraction of muscle and liver (0.4% to 0.9%). There were no major differences in the total FA composition of liver and muscle between the dietary groups; except for a small increase of n-3 polyunsaturated FAs (PUFAs) in liver of the DTA group. The mRNA expression of peroxisome proliferator-activated receptor (PPAR) α, apolipoprotein AI (ApoAI), apolipoprotein CII (ApoCII) and low-density lipoprotein receptor (LDL-R) was down-regulated in liver of the salmon fed 0.3% DTA. PPARα and ApoAI transcripts were also reduced in liver of salmon fed 0.6% TTA. Additionally, the hepatic lipoprotein lipase (LPL) mRNA level was 3.8 fold increased in TTA fish relative to the FO group. In muscle there were no significant changes in gene expression pattern of any of the genes investigated. This is the first report on the effects of 3-thia FAs on gene expression in Atlantic salmon.

Pomegranate seed oil rich in conjugated linolenic acid suppresses chemically induced colon carcinogenesis in rats.

Pomegranate (Punica granatum L.) seed oil (PGO) contains more than 70% cis(c)9,trans(t)11,c13-18:3 as conjugated linolenic acids (CLN). Our previous short-term experiment demonstrated that seed oil from bitter melon (Momordica charantia) (BMO), which is rich in c9,t11,t13-CLN, inhibited the occurrence of colonic aberrant crypt foci (ACF) induced by azoxymethane (AOM). In this study, we investigated the effect of dietary PGO on the development of AOM-induced colonic malignancies and compared it with that of conjugated linoleic acid (CLA). To induce colonic tumors, 6-week old male F344 rats were given subcutaneous injections of AOM (20 mg/kg body weight) once a week for 2 weeks. One week before the AOM treatment they were started on diet containing 0.01%, 0.1%, or 1% PGO or 1% CLA for 32 weeks. Upon termination of the bioassay (32 weeks) colon tumors were evaluated histopathologically. AOM exposure produced colonic adenocarcinoma with an incidence of 81% and multiplicity of 1.88 +/- 1.54 at week 32. Administration of PGO in the diet significantly inhibited the incidence (AOM + 0.01% PGO, 44%, P < 0.05; AOM + 0.1% PGO, 38%, P < 0.01; AOM + 1% PGO, 56%) and the multiplicity (AOM + 0.01% PGO, 0.56 +/- 0.73, P < 0.01; AOM + 0.1% PGO, 0.50 +/- 0.73, P < 0.005; AOM + 1% PGO, 0.88 +/- 0.96, P < 0.05) of colonic adenocarcinomas, although a clear dose-response relationship was not observed at these dose levels. CLA feeding also slightly, but not significantly, reduced the incidence and multiplicity of colonic adenocarcinomas. The inhibition of colonic tumors by PGO was associated with an increased content of CLA (c9,t11-18:2) in the lipid fraction of colonic mucosa and liver. Also, administration of PGO in the diet elevated expression of peroxisome proliferator-activated receptor (PPAR) gamma protein in the non-tumor mucosa. These results suggest that PGO rich in c9,t11,c13-CLN can suppress AOM-induced colon carcinogenesis, and the inhibition is associated in part with the increased content of CLA in the colon and liver and/or increased expression of PPARgamma protein in the colon mucosa.

Effects of dietary n-3 polyunsaturated fatty acids, breed and dietary vitamin E on the fatty acids of lamb muscle, liver and adipose tissue.

The effect of feeding n-3 PUFA on the fatty acid composition of muscle, adipose tissue and liver of lambs was investigated. Groups of eight ram lambs per breed, SuffolkxLleyn (24 kg live weight) and Scottish Blackface (18 kg live weight), were each fed one of six diets containing one of three fat sources (50 g fatty acids/kg DM; Megalac((R)) (calcium soap of palm fatty acid distillate; Volac Ltd, Royston, Herts., UK) and formaldehyde-treated whole linseed (Trouw Nutrition UK, Northwich, Ches., UK) either alone or with fish oil (1:1, w/w) and either 100 or 500 mg alpha-tocopheryl acetate/kg DM. Feed was offered ad libitum until slaughter at approximately half breed mature live weight. The type of dietary fat had no effect on intake, growth rate or feed conversion ratio. The 3.0-fold higher concentration of 18 : 3n-3 in the linseed compared with the Megalac((R)) diet approximately doubled (P<0.001) the concentration in the neutral and polar lipid fractions of musculus semimembranosus and liver, and in adipose tissue it increased 2.5-fold. Feeding protected linseed also increased (P<0.001) concentrations of 20 : 5n-3 and 22 : 5n-3 in muscle polar lipids and both lipid fractions of liver. The linseed-fish oil raised the 20 : 5n-3 concentrations above those for the linseed diet and also increased 22 : 6n-3. Scottish Blackface lambs had lower concentrations of 18 : 3n-3 in all lipids compared with Suffolk x Lleyn lambs, but more 20 : 5n-3 in the polar lipids of muscle and liver. High levels of dietary vitamin E were associated with small decreases in the concentration of monounsaturated fatty acids and increases in PUFA. Linseed raised the PUFA : saturated fatty acid ratios in liver and adipose tissue but not in muscle, and improved the n-6 : n-3 fatty acid ratio, as did the linseed-fish oil. Different combinations of dietary fatty acids and better protection against rumen biohydrogenation are required to improve muscle PUFA : saturated fatty acids ratios.

Contrasting effects of t10,c12- and c9,t11-conjugated linoleic acid isomers on the fatty acid profiles of mouse liver lipids.

The purpose of this study was to examine the effects of two purified isomers of CLA (c9,t11-CLA and t10,c12-CLA) on the weights and FA compositions of hepatic TG, phospholipids, cholesterol esters, and FFA. Eight-week-old female mice (n = 6/group) were fed either a control diet or diets supplemented with 0.5% c9,t11-CLA or t10,c12-CLA isomers for 8 wk. Weights of liver total lipids and those of individual lipid fractions did not differ between the control and the c9,t11-CLA groups. Livers from animals fed the t10, c12-CLA diet contained four times more lipids than those of the control group; this was mainly due to an increase in the TG fractions (fivefold), but cholesterol (threefold), cholesterol esters (threefold), and FFA (twofold) were also significantly increased. Although c9,t11-CLA did not significantly alter the weights of liver lipids when compared with the control group, its intake was associated with significant reductions in the weight percentage (wt% of total FAME) of 18:1n-9 and 18:1n-7 in the TG fraction and with significant increases in the weight percentage of 18:2n-6 in the TG, cholesterol ester, and phospholipid fractions. On the other hand, t10,c12-CLA intake was linked with a significant increase in the weight percentage of 18:1n-9 and a decrease in that of 18:2n-6 in all lipid fractions. These changes may be the result of alterations in the activity of delta9-desaturase (stearoyl CoA desaturase) and the enzymes involved in the metabolism of 18:2n-6. Thus, the two isomers differed not only in their effects on the weights of total liver lipids and lipid fractions but also on the FA profile of the lipid fractions.

Effects of n-3 Polyunsaturated Fatty Acids-enriched Diet Supplemented with Different Levels of α-Tocopherol on Lipid Metabolism in Laying Tsaiya Ducks

The objective of this experiment was to determine the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs)-enriched diet supplemented with different levels of α-tocopherol on the activities of hepatic lipogenic-related enzymes and the contents of liver and plasma lipid fractions in laying Tsaiya ducks. A total of 180 30-wk-old laying Tsaiya ducks, at the beginning of peak production, were allotted into 6 treatments with 3 replicates each. Ducks were fed one of the 6 experimental diets, containing 4% tallow (control), and 4% fish oil supplemented with graded levels of α-tocopheryl acetate (α-tocopherol) at 0, 100, 200, 300 and 400 mg/kg, respectively, for 6 wks. Feed and water were supplied ad libitum throughout the experimental period. The results indicated that the n-3 PUFAs- enriched diet supplemented with different levels of α-tocopherol did not affect (p>0.05) egg weight, feed intake, body weight change or liver and abdominal fat weights. Egg production, egg mass and feed efficiency significantly (p<0.05) improved as dietary α-tocopherol levels increased. The activities of hepatic lipogenic-related enzymes including acetyl-CoA carboxylase (EC 6. 2. 1. 3; ACC), glucose-6- phosphate dehydrogenase (EC 1. 1. 1. 49; G-6-PDH), ATP-citrate cleavage enzyme (EC 4. 1. 3. 8; CCE), NADP-malate dehydrogenase (EC 1.1.1.40; NADP-MDH) and fatty acid synthetase (FAS) were higher (p<0.05) in birds fed with the tallow diet than in those fed with fish oil diets and increased with increasing dietary α-tocopherol levels. None of the dietary treatments significantly affected the contents of triglyceride and total cholesterol in the liver, or total cholesterol, phospholipid and total lipid in the plasma. However, the contents of phospholipid and total lipid in the liver, and triglyceride in the plasma increased as dietary α-tocopherol levels increased. Increasing dietary α-tocopherol levels decreased the non-esterified fatty acid (NEFA) content in the plasma and trended to decrease the cholesterol contents in the egg yolk. The lipid metabolism of laying Tsaiya ducks was influenced not only by the dietary fat but also by the supplementation levels of α-tocopherol. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 11 : 1562-1569)

On Adaptative Changes of Rates of Oxygen Consumption and Lipid Metabolism in Littorina saxatilis at Parasitic Invasions

Effects of parasites as a biotic factor on physiological and some biochemical characteristics of gastropod molluscs Littorina saxatilis are considered. The individuals infected at young age and incapable for reproduction due to parasitic castration have a lower intensity of respiration as compared with non-infected individuals of the same size. Large infected individuals that had time to realize their reproductive potential before pathological changes in hepatopancreas do not differ in respiration from the normal individuals. Comparative analysis of the lipid fraction of liver, particularly of the fatty acid (FA) composition of total lipids and phospholipids, allowed revealing essential differences between the control and infected individuals, as well as between infected individuals of different age groups. The absence of glycogen in the liver of infected L. saxatilis, which is revealed using thin-layer chromatography, indicates functional disturbances, including those in glycogen synthesis. We suggest that the reduction of intensity of metabolism in infected individuals is connected with peculiarities of digestive process at structural changes in the hepatopancreas damaged by sporocysts. In infected molluscs the FA composition relates mainly to parasite tissues than to the liver itself. In this connection, the role of lipids in regulation of enzyme activity and permeability of cell membranes is directed first of all to maintenance of parasite metabolism. The revealed elevated synthesis of stearic acid in infected individuals can be connected with its accumulation in parasite adipose cells. The FA composition of phospholipids in infected individuals had changes that can be directed to realization of barrier function of cell membranes, specifically to restriction of the rate of oxygen diffusion into sporocysts owing to condensation of membranes. Together with adaptive changes in FA composition the ratios saturated FA : unsaturated FA and ω3 : ω6 acids in control and infected individuals were preserved at the constant level, which in any case is connected with maintenance of normal functioning of cell membranes.