The effect of camelina oil on vascular function in essential hypertensive patients with metabolic syndrome: a randomized, placebo-controlled, double-blind study.

BACKGROUND: The effects of a dietary supplementation with the vegetable ω-3 α-linolenic acid (ALA) on cardiovascular homeostasis are unclear. In this context, it would be interesting to assess the effects of camelina oil. OBJECTIVE: This study aimed to assess the cardiovascular and metabolic effects of camelina oil in hypertensive patients with metabolic syndrome. METHODS: In a double-blind, placebo-controlled randomized study, treated essential hypertensive patients with metabolic syndrome received, during 6 mo, either cyclodextrin-complexed camelina oil containing ≈ 1.5 g ALA/d (n = 40) or an isocaloric placebo (n = 41), consisting of the same quantity of cyclodextrins and wheat starch. Anthropometric data, plasma lipids, glycemia, insulinemia, creatininemia, TBARs, high-sensitivity C-reactive protein, and n-3, n-6, and n-9 fatty acids in erythrocyte membranes were measured. Peripheral and central blood pressures, arterial stiffness, carotid intima-media thickness, and brachial artery endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent dilatation were assessed. RESULTS: Compared with placebo, camelina oil increased ALA (mean ± SD: 0 ± 0.04 compared with 0.08 ± 0.06%, P <0.001), its elongation product EPA (0 ± 0.5 compared with 0.16 ± 0.65%, P <0.05), and the n-9 gondoic acid (GA; 0 ± 0.04 compared with 0.08 ± 0.04%, P <0.001). No between-group difference was observed for cardiovascular parameters. However, changes in FMD were associated with the magnitude of changes in EPA (r = 0.26, P = 0.03). Compared with placebo, camelina oil increased fasting glycemia (-0.2 ± 0.6 compared with 0.3 ± 0.5 mmol/L, P <0.001) and HOMA-IR index (-0.8 ± 2.5 compared with 0.5 ± 0.9, P <0.01), without affecting plasma lipids, or inflammatory and oxidative stress markers. Changes in HOMA-IR index were correlated with the magnitude of changes in GA (r = 0.32, P <0.01). Nutritional intake remained similar between groups. CONCLUSION: ALA supplementation with camelina oil did not improve vascular function but adversely affected glucose metabolism in hypertensive patients with metabolic syndrome. Whether this adverse effect on insulin sensitivity is related to GA enrichment, remains to be elucidated.

Rapeseed oil fortified with micronutrients improves cognitive alterations associated with metabolic syndrome.

Metabolic syndrome represents a major risk factor for severe comorbidities such as cardiovascular diseases or diabetes. It is also associated with an increased prevalence of emotional and cognitive alterations that in turn aggravate the disease and related outcomes. Identifying therapeutic strategies able to improve those alterations is therefore a major socioeconomical and public health challenge. We previously reported that both hippocampal inflammatory processes and neuronal plasticity contribute to the development of emotional and cognitive alterations in db/db mice, an experimental model of metabolic syndrome that displays most of the classical features of the syndrome. In that context, nutritional interventions with known impact on those neurobiological processes appear as a promising alternative to limit the development of neurobiological comorbidities of metabolic syndrome. We therefore tested here whether n-3 polyunsaturated fatty acids (n-3 PUFAs) associated with a cocktail of antioxidants can protect against the development of behavioral alterations that accompany the metabolic syndrome. Thus, this study aimed: 1) to evaluate if a diet supplemented with the plant-derived n-3 PUFA α-linolenic acid (ALA) and antioxidants (provided by n-3 PUFAs-rich rapeseed oil fortified with a mix of naturally constituting antioxidant micronutrients, including coenzyme Q10, tocopherol, and the phenolic compound canolol) improved behavioral alterations in db/db mice, and 2) to decipher the biological mechanisms underlying this behavioral effect. Although the supplemented diet did not improve anxiety-like behavior and inflammatory abnormalities, it reversed hippocampus-dependent spatial memory deficits displayed by db/db mice in a water maze task. It concomitantly changed subunit composition of glutamatergic AMPA and NMDA receptors in the hippocampus that has been shown to modulate synaptic function related to spatial memory. These data suggest that changes in local neuronal plasticity may underlie cognitive improvements in db/db mice fed the supplemented diet. The current findings might therefore provide valuable data for introducing new nutritional strategies for the treatment of behavioral complications associated with MetS.

Vitamin D supplementation and muscle strength in pre-sarcopenic elderly Lebanese people: a randomized controlled trial.

Previous studies have shown that improving vitamin D status among the elderly may lead to an improvement in muscle mass and muscle strength. In our study, vitamin D supplementation showed significant improvements in vitamin D concentrations as well as appendicular muscle mass in pre-sarcopenic older Lebanese people. However, we found no significant effect on muscle strength. INTRODUCTION: Improving vitamin D status might improve muscle function and muscle mass that lead to sarcopenia in older subjects. The aim of this randomized, controlled, double-blind study was to examine the effect of vitamin D supplementation on handgrip strength and appendicular skeletal muscle mass in pre-sarcopenic older Lebanese subjects. We also examined whether this effect differs in normal vs. obese subjects. METHODS: Participants (n = 128; 62 men and 66 women) deficient in vitamin D (25(OH)D = 12.92 ± 4.3 ng/ml) were recruited from Saint Charles Hospital, Beirut, Lebanon. The participants were given a supplement of 10,000 IU of cholecalciferol (vitamin D group; n = 64) to be taken three times a week or a placebo tablet (placebo group; n = 64) for 6 months. One hundred fifteen subjects completed the study: 59 had normal weight, while 56 were obese. Strength and functional assessment and biochemical analysis were performed at the start and after 6 months. RESULTS: Compared to placebo, the vitamin D supplemented group showed significant improvements in appendicular skeletal muscle mass (ASMM) (P < 0.001) but not in handgrip strength (P = 0.2901). ANCOVA for ASMM adjusting for obesity and including the interaction between obesity and vitamin D showed a significant interaction. The increase in ASMM with vitamin D in normal-weight subjects was higher than that of obese subjects (B = 35.09 vs. B = 2.19). CONCLUSION: Treatment with vitamin D showed beneficial effects on appendicular muscle mass in pre-sarcopenic older Lebanese men and women. However, it had no effect on muscle strength relative to placebo. This trial was registered at isrctn.org as ISRCTN16665940.

Rapeseed oil fortified with micronutrients can reduce glucose intolerance during a high fat challenge in rats.

BACKGROUND: Better choices of dietary lipid sources and substitution of refined by fortified oils could reduce the intake of saturated fatty acids (FA) and increase the intake of omega 3 FA concomitantly to healthy bioactive compounds. METHODS: The development of obesity and metabolic disturbances was explored in rats fed during 11 weeks with a high fat diet (HFD) in which the amount of saturated and polyunsaturated FA was respectively reduced and increased, using rapeseed oil as lipid source. This oil was used in a refined form (R) or fortified (10 fold increase in concentration) with endogenous micronutrients (coenzyme Q10 + tocopherol only (RF) only and also with canolol (RFC)). The effect of substituting palm by rapeseed oil was analysed using a student t test, oil fortification was analysed using ANOVA statistical test. RESULTS: Despite a similar weight gain, diets R, RF and RFC improved glucose tolerance (+ 10%) of the rats compared to a standard HFD with palm and sunflower oils as lipid source. Plasma glucose was lowered in RF and RFC groups (- 15 and 23% respectively), although triacylglycerol level was only reduced in group RFC (- 33%) compared to R. The fortification with canolol promoted the activation of Akt and AMP-activated protein kinase (AMPK) in skeletal muscle and subcutaneous adipose tissue respectively. Canolol supplementation also led to reduce p38 MAPK activation in skeletal muscle. CONCLUSIONS: This study suggests that the presence of endogenous micronutrients in rapeseed oil promotes cellular adaptations to reverse glucose intolerance and improve the metabolism of insulin sensitive tissues.

Dietary canolol protects the heart against the deleterious effects induced by the association of rapeseed oil, vitamin E and coenzyme Q10 in the context of a high-fat diet.

BACKGROUND: Obesity progressively leads to cardiac failure. Omega-3 polyunsaturated fatty acids (PUFA) have been shown to have cardio-protective effects in numerous pathological situations. It is not known whether rapeseed oil, which contains α-linolenic acid (ALA), has a similar protective effect. Omega-3 PUFAs are sensitive to attack by reactive oxygen species (ROS), and lipid peroxidation products could damage cardiac cells. We thus tested whether dietary refined rapeseed oil (RSO) associated with or without different antioxidants (vitamin E, coenzyme Q10 and canolol) is cardio-protective in a situation of abdominal obesity. METHODS: Sixty male Wistar rats were subdivided into 5 groups. Each group was fed a specific diet for 11 weeks: a low-fat diet (3% of lipids, C diet) with compositionally-balanced PUFAs; a high-fat diet rich in palm oil (30% of lipids, PS diet); the PS diet in which 40% of lipids were replaced by RSO (R diet); the R diet supplemented with coenzyme Q10 (CoQ10) and vitamin E (RTC diet); and the RTC diet supplemented with canolol (RTCC diet). At the end of the diet period, the rats were sacrificed and the heart was collected and immediately frozen. Fatty acid composition of cardiac phospholipids was then determined. Several features of cardiac function (fibrosis, inflammation, oxidative stress, apoptosis, metabolism, mitochondrial biogenesis) were also estimated. RESULTS: Abdominal obesity reduced cardiac oxidative stress and apoptosis rate by increasing the proportion of arachidonic acid (AA) in membrane phospholipids. Dietary RSO had the same effect, though it normalized the proportion of AA. Adding vitamin E and CoQ10 in the RSO-rich high fat diet had a deleterious effect, increasing fibrosis by increasing angiotensin-2 receptor-1b (Ag2R-1b) mRNA expression. Overexpression of these receptors triggers coronary vasoconstriction, which probably induced ischemia. Canolol supplementation counteracted this deleterious effect by reducing coronary vasoconstriction. CONCLUSION: Canolol was found to counteract the fibrotic effects of vitamin E + CoQ10 on cardiac fibrosis in the context of a high-fat diet enriched with RSO. This effect occurred through a restoration of cardiac Ag2R-1b mRNA expression and decreased ischemia.

Plant-based foods as a source of lipotropes for human nutrition: a survey of in vivo studies.

Increased consumption of plant products is associated with lower chronic disease prevalence. This is attributed to the great diversity of healthy phytochemicals present in these foods. The most investigated physiological effects have been their antioxidant, anti-carcinogenic, hypolipidemic, and hypoglycemic properties. Although less studied in humans, some compounds were very early on shown to be lipotropic in animals, i.e., the capacity to hasten the removal of fat from liver and/or reduce hepatic lipid synthesis or deposits by mainly increasing phospholipid synthesis via the transmethylation pathway for triglyceride-rich lipoprotein exportation from the liver and enhanced fatty acid ß-oxidation and/or down- and up-regulation of genes involved in lipogenic and fatty acid oxidation enzyme synthesis, respectively. The main plant lipotropes are choline, betaine, myo-inositol, methionine, and carnitine. Magnesium, niacin, pantothenate, and folates also indirectly support the overall lipotropic effect. The exhaustive review of rat studies investigating phytochemical effect on hepatic lipid metabolism suggests that some fatty acids, acetic acid, melatonin, phytic acid, some fiber compounds, oligofructose, resistant starch, some phenolic acids, flavonoids, lignans, stilbenes, curcumin, saponins, coumarin, some plant extracts, and some solid foods may be lipotropic. However, this remains to be confirmed in humans, for whom intervention studies are practically non-existent. Supplemental materials are available for this article. Go to the publisher's online edition of Critical Reviews in Food Science and Nutrition® to view the free supplemental file.

Optimized rapeseed oil enriched with healthy micronutrients: a relevant nutritional approach to prevent cardiovascular diseases. Results of the Optim'Oils randomized intervention trial.

Rapeseeds are naturally rich in cardioprotective micronutrients but refining leads to substantial losses or the production of undesirable compounds. The Optim'Oils European project proposed innovative refining conditions to produce an optimized rapeseed oil enriched in micronutrients and low in trans linolenic acid. We aimed to investigate cardioprotective properties of this Optimized oil. In a randomized, double-blind, controlled, cross-over study, 59 healthy normolipidaemic men consumed either Optimized or Standard rapeseed oils (20 g/d) and margarines (22 g/d) for 3 weeks. The Optimized oil reduced the trans FA concentration (p=0.009) and increased the contents of alpha-tocopherol (p=0.022) and coenzyme Q10 (p<0.001) in comparison with the Standard oil. Over the 3-week trial, Total-/HDL-cholesterol and LDL-/HDL-cholesterol were increased by 4% (p<0.05) with the Standard oil consumption whereas none of them rose with the Optimized rapeseed oil which increased the HDL-cholesterol and ApoA1 plasma content (+2%, NS and +3%, p<0.05 respectively). The effects observed on the plasma HDL-cholesterol levels (p=0.059), the Total-/HDL-cholesterol ratio (p=0.092), and on the ApoA1 concentrations (p=0.060) suggest an improvement of the cholesterol profile with the Optimized rapeseed oil. Finally, the Optimized oil reduced the plasma content of LDLox (-6%, NS), this effect being significantly different from the Standard oil (p=0.050). In conclusion, reasonable intake of an Optimized rapeseed oil resulting from innovative refining processes and enriched in cardioprotective micronutrients represent a relevant nutritional approach to prevent the risk of cardiovascular diseases by improving the cholesterol profile and reducing LDL oxidation.

Increasing intake of long-chain n-3 PUFA enhances lipoperoxidation and modulates hepatic gene expression in a dose-dependent manner.

Long-chain (LC) n-3 PUFA have a broad range of biological properties that can be achieved at the gene expression level. This has been well described in liver, where LC n-3 PUFA modulate the expression of genes related to lipid metabolism. However, the complexity of biological pathway modulations and the nature of bioactive molecules are still under investigation. The present study aimed to investigate the dose-response effects of LC n-3 PUFA on the production of peroxidised metabolites, as potential bioactive molecules, and on global gene expression in liver. Hypercholesterolaemic rabbits received by daily oral administration (7 weeks) either oleic acid-rich oil or a mixture of oils providing 0.1, 0.5 or 1 % (groups 1, 2 and 3 respectively) of energy as DHA. Levels of specific peroxidised metabolites, namely 4-hydroxyhexenal (4-HHE)-protein adducts, issued from LC n-3 PUFA were measured by GC/MS/MS in liver in parallel to transcription profiling. The intake of LC n-3 PUFA increased, in a dose-dependent manner, the hepatic production of 4-HHE. At the highest dose, LC n-3 PUFA provoked an accumulation of TAG in liver, which can be directly linked to increased mRNA levels of lipoprotein hepatic receptors (LDL-receptor and VLDL-receptor). In groups 1 and 2, the mRNA levels of microsomal TAG transfer protein decreased, suggesting a possible new mechanism to reduce VLDL secretion. These modulations of genes related to lipoprotein metabolism were independent of PPARα signalling but were probably linked to the activation of the farnesol X receptor pathway by LC n-3 PUFA and/or their metabolites such as HHE.

Borage and fish oils lifelong supplementation decreases inflammation and improves bone health in a murine model of senile osteoporosis.

Fats are prevalent in western diets; they have known deleterious effects on muscle insulin resistance and may contribute to bone loss. However, relationships between fatty acids and locomotor system dysfunctions in elderly population remain controversial. The aim of this study was to analyze the impact of fatty acid quality on the age related evolution of the locomotor system and to understand which aging mechanisms are involved. In order to analyze age related complications, the SAMP8 mouse strain was chosen as a progeria model as compared to the SAMR1 control strain. Then, two months old mice were divided in different groups and subjected to the following diets : (1) standard "growth" diet - (2) "sunflower" diet (high ω6/ω3 ratio) - (3) "borage" diet (high γ-linolenic acid) - (4) "fish" diet (high in long chain ω3). Mice were fed ad libitum through the whole protocol. At 12 months old, the mice were sacrificed and tissues were harvested for bone studies, fat and muscle mass measures, inflammation parameters and bone cell marker expression. We demonstrated for the first time that borage and fish diets restored inflammation and bone parameters using an original model of senile osteoporosis that mimics clinical features of aging in humans. Therefore, our study strongly encourages nutritional approaches as relevant and promising strategies for preventing aged-related locomotor dysfunctions.

Laparoscopic implantation of neural electrodes on pelvic nerves: an experimental study on the obturator nerve in a chronic minipig model.

BACKGROUND: Laparoscopic exposure of pelvic nerves has opened a new area in the field of neuromodulation. However, electrode design and material deterioration remain issues that limit clinical application. The objective of this study was to evaluate experimentally the laparoscopic implantation of different types of neural electrodes in order to achieve functional and selective electrical stimulation of pelvic nerves. METHODS: This was a prospective comparative study of the laparoscopic implantation and tolerance and efficacy of three monopolar cuff electrodes implanted on the obturator nerve in ten Göttingen minipigs (18-20 months old; 14.5-24 kg body weight). Animals were allocated to two groups. A 3-mm-diameter laparoscopic instrument was used during dissection of paravesical fossa and obturator nerve on both sides in order to minimize nerve damage. In all animals, a "split-cylinder" cuff electrode was implanted around the left obturator nerve. On the right side, a "lasso" cuff electrode was implanted in the first group and a "closed-cylinder" cuff was implanted in the second group. Electrical stimulation (0-5 V, 20 Hz) was performed for implanted electrodes on days 0, 7, 15, 30, 45, 60, and 90. Current intensity thresholds were identified by palpation of muscle contraction. Strength developed according to stimulation level and was measured using weight transducers. RESULTS: All procedures were performed by laparoscopy. Mean operative times differed significantly among groups, the shortest being for split-cylinder electrodes (P = 0.0002). No electrical spread phenomena were observed. Initial thresholds were below 1.5 V (range = 0.5-1.3); however, a significant rise was observed, with time to a maximum of 2.7 V (P < 0.0001). Only split-cylinder electrodes remained functional after 3 months. The mean value of maximum strength remained stable during the study period (P = 0.21, NS). CONCLUSIONS: The laparoscopic approach to implanting neuroprostheses seems to be very attractive. Furthermore, this approach could allow highly selective nerve stimulation to be achieved using simpler devices such as split-cylinder monopolar electrodes.

Comparison of postprandial oleic acid, 9c,11t CLA and 10t,12c CLA oxidation in healthy moderately overweight subjects.

Few studies report the individual effect of 9c,11t- and 10t,12c-CLA on human energy metabolism. We compared the postprandial oxidative metabolism of 9c,11t- and 10t,12c-CLA and oleic acid (9c-18:1) in 22 healthy moderately overweight volunteers. After 24 weeks supplementation with 9c,11t-, 10t,12c-CLA or 9c-18:1 (3 g/day), subjects consumed a single oral bolus of the appropriate [1-(13)C]-labeled fatty acid. 8 h post-dose, cumulative oxidation was similar for 9c-18:1 and 10t,12c (P = 0.66), but significantly higher for 9c,11t (P < 0.01).

An α-linolenic acid-rich formula reduces oxidative stress and inflammation by regulating NF-κB in rats with TNBS-induced colitis.

We have previously shown that α-linolenic acid (ALA), a (n-3) PUFA exerts in vitro antiinflammatory effects in the intestine. In this study, we aimed to evaluate its effect on inflammatory and oxidative stress in a colitis model. Colitis was induced in 2 groups at d 0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS), whereas the control group received the vehicle. Rats we fed 450 mg . kg(-1) . d(-1) of ALA (TNBS+ALA) while the other colitic group (TNBS) and the control group were fed an isocaloric corn oil formula for 14 d (from d -7 to d 7). RBC fatty acid composition was assessed. Oxidative stress was studied by measuring urinary 8-isoprostanes (8-IP) and colon glutathione (GSH) concentration and inducible nitric oxide synthase (iNOS) expression. Colitis was assessed histologically, by production of proinflammatory mediators, including cytokines, leukotrienes B(4) (LTB(4)), and cyclooxygenase-2 (COX-2) and by nuclear factor-κB (NF-κB) activation. The ALA-rich diet significantly increased the RBC levels of ALA, eicosapentaenoic acid, and docosapentaenoic acid (n-3) compared with the TNBS group (P < 0.01 for all). The beneficial effect of ALA supplementation on oxidative stress was reflected by lower urinary 8-IP levels (P < 0.05), a normalized colon GSH concentration (P < 0.01), and reduced colon iNOS expression (P < 0.05) compared with the TNBS group. ALA also protected against colon inflammation as assessed by lower tumor necrosis factor-α secretion and mRNA level (P < 0.05), reduced NF-κB activation (P = 0.01), and lower colon lipid mediator concentrations such as LTB(4) and COX-2 (P < 0.05) compared with the TNBS group. These findings show that an ALA-rich formula is beneficial to TNBS-induced colitic rats via inhibition of oxidative and inflammatory stress.

Effects of fish oil and starch added to a diet containing sunflower-seed oil on dairy goat performance, milk fatty acid composition and in vivo delta9-desaturation of [13C]vaccenic acid.

The potential benefits on human health have prompted an interest in developing nutritional strategies for specifically increasing rumenic acid (RA) in ruminant milk. The aims of the present study were to (i) compare two dietary treatments with lipid supplements on milk yield and composition, (ii) measure the in vivo delta9-desaturation of vaccenic acid (VA) to RA using 13C-labelled VA and (iii) determine the effect of the dietary treatments on this variable. Treatments were 90 g sunflower-seed oil (SO) per d or 60 g sunflower-seed oil and 30 g fish oil per d plus additional starch (SFO), in a grassland hay-based diet given to eight Alpine goats in a 2 x 2 cross-over design with 21 d experimental periods. Milk yield and composition were similar between treatments. Goats fed SFO had higher milk 6 : 0-16 : 0 concentration, lower milk sigmaC18 concentrations and showed no effect on milk VA and RA, compared with SO. At the end of the experiment, intravenous injection of 1.5 g [13C]VA followed by measurements of milk lipid 13C enrichment showed that in vivo 31.7 and 31.6 % of VA was delta9-desaturated into milk RA in the caprine with the SO and SFO treatments, respectively. The expression of genes encoding for delta9-desaturase (or stearoyl-CoA desaturase; SCD1, SCD5) in mammary tissues and four milk delta9-desaturation ratios were similar between treatments. In conclusion, the present study provides the first estimates of in vivo endogenous synthesis of RA (63-73 % of milk RA) from VA in goats, and shows no difference between the two lipid supplements compared.

Effect of dietary polyunsaturated fatty acids on the expression of peroxisomal ABC transporters.

Peroxisomal ABC transporters encoded by the ABCD genes are thought to participate in the import of specific fatty acids in the peroxisomal matrix. ABCD1 deficiency is associated with X-linked adrenoleukodystrophy (X-ALD), the most frequent peroxisomal disorder which is characterized by the accumulation of saturated very-long-chain fatty acids (VLCFA). ABCD2 (the closest homolog of ABCD1) and ABCD3 have been shown to have partial functional redundancy with ABCD1; only when overexpressed, they can compensate for VLCFA accumulation. Other lipids, for instance polyunsaturated fatty acids (PUFA), should be possible candidate substrates for the ABCD2 and ABCD3 gene products, ALDRP and PMP70 respectively. Moreover, PUFA, which are known regulators of gene expression, could therefore represent potent inducers of the ABCD genes. To test this hypothesis, littermates of n-3-deficient rats were subjected to an n-3-deficient diet or equilibrated diets containing ALA (alpha-linolenic acid, 18:3n-3) as unique source of n-3 fatty acids or ALA plus DHA (docosahexaenoic acid, 22:6n-3) at two different doses. We analyzed the expression of peroxisomal ABC transporters and of the peroxisomal acyl-CoA oxidase gene 1 (Acox1) in adrenals, brain and liver. Whatever the diet, we did not observe any difference in gene expression in adrenals and brain. However, the hepatic expression level of Abcd2 and Abcd3 genes was found to be significantly higher in the n-3-deficient rats than in the rats fed the ALA diet or the DHA supplemented diets. This was accompanied by important changes in hepatic fatty acid composition. In summary, the hepatic expression of Abcd2 and Abcd3 but not of Abcd1 and Abcd4 appears to be highly sensitive towards dietary PUFA. This difference could be linked to the substrate specificity of the peroxisomal ABC transporters and a specific involvement of Abcd2 and Abcd3 in PUFA metabolism.

Olfactory discrimination ability and brain expression of c-fos, Gir and Glut1 mRNA are altered in n-3 fatty acid-depleted rats.

The long-chain polyunsaturated n-3 fatty acids (n-3 PUFA), particularly docosahexaenoic acid (DHA), are abundantly present in the central nervous system and play an important role in cognitive functions such as learning and memory. We, therefore, investigated the effects of n-3 PUFA-depletion in rats (F2 generation) on the learning of an olfactory discrimination task, progressively acquired within a four-arm maze, and on the mRNA expression of some candidate genes, i.e., c-fos, Gir and glucose transporter (Glut1), which could reflect the level of cerebral activity. We observed that DHA contents were dramatically decreased in the olfactory bulb, the piriform cortex and the neocortex of n-3-depleted rats. Furthermore, the n-3 deficiency resulted in a mild olfactory learning impairment as these rats required more days to master the olfactory task compared to control rats. Real-time RT-PCR experiments revealed that the training induced the expression of c-fos mRNA in all the three regions of the brain whereas Gir and Glut1 mRNA were induced only in olfactory bulb and neocortex. However, such an increase was less marked in the n-3-deficient rats. Taken together, these results allow us to assume that the behavioural impairment in n-3-deficient rats is linked to the depletion of n-3 fatty acids in brain regions processing olfactory cues. Data are discussed in view of the possible role of some of these genes in learning-induced neuronal olfactory plasticity.

Phospholipid fatty acid pattern and D-glucose metabolism in muscles from omega3 fatty acid-depleted rats.

A depletion in long-chain polyunsaturated omega3 fatty acids may affect fuel homeostasis. In such a perspective, the present study deals mainly with the in vitro fate of D-[U-(14)C]glucose in hemidiaphragms, stretched soleus and plantaris muscle pieces obtained from normal and omega3-depleted rats (second generation) and incubated in the absence or presence of insulin. When so required, the omega3-depleted rats were injected 120 min before sacrifice with either a omega3 fatty acid-rich medium-chain triglyceride:fish oil emulsion (FO) or a control medium-chain triglyceride:olive oil emulsion (OO). The content of the soleus muscle in long-chain polyunsaturated omega3 fatty acids was severely decreased in the omega3-depleted rats, and modestly albeit significantly increased after injection of FO to these animals. In stretched soleus muscles from OO-injected omega3-depleted rats, the absolute values for glycogen synthesis measured in the absence or presence of insulin were about twice higher than in normal animals. In the OO-injected omega3-depleted rats, insulin augmented the output of (14)C-labelled amino acids, whilst such was not the case in normal animals. These and other findings suggest a lower catabolism of D-glucose relative to the anabolic process of glycogen synthesis and a lower availability of endogenous amino acids in the muscles of omega3-depleted rats, as compared to those of control animals. The prior injection of FO to the omega3-depleted rats restored a normal value for the paired ratio between the output of (14)C-labelled amino acids and acidic metabolites, but further increased glycogen net synthesis. It is proposed, therefore, that the perturbation of d-glucose metabolism in muscles from omega3-depleted rats involves a multifactorial determinism, only some of the concerned factors being susceptible to rapid correction after enrichment of cell phospholipids in long-chain polyunsaturated omega3 fatty acids.

Pancreatic islet function in omega3 fatty acid-depleted rats: Glucose metabolism and nutrient-stimulated insulin release.

In order to gain information on the determinism of the perturbation of fuel homeostasis in situations characterized by a depletion in long-chain polyunsaturated omega3 fatty acids (omega3), the metabolic and hormonal status of omega3-depleted rats (second generation) was examined. When required, these rats were injected intravenously 120 min before sacrifice with a novel medium-chain triglyceride-fish oil emulsion able to provoke a rapid and sustained increase of the omega3 content in cell phospholipids. The measurement of plasma glucose, insulin, phospholipid, triglyceride, and unesterified fatty acid concentration indicated modest insulin resistance in the omega3-depleted rats. The plasma triglyceride and phospholipid concentrations were decreased in the omega3-depleted rats with abnormally low contribution of omega3 in both circulating and pancreatic islet lipids. The protein, insulin, and lipid content of the islets, as well as their intracellular and extracellular spaces, were little affected in the omega3-depleted rats. The metabolism of D-glucose in the islets of omega3-depleted rats was characterized by a lesser increase in D-[5-3H]glucose utilization and D-[U-14C]glucose oxidation in response to a given rise in hexose concentration and an abnormally low ratio between D-glucose oxidation and utilization. These abnormalities could be linked to an increased metabolism of endogenous fatty acids with resulting alteration of glucokinase kinetics. The release of insulin evoked by D-glucose, at a close-to-physiological concentration (8.3 mM), was increased in the omega3-depleted rats, this being considered as consistent with their insulin resistance. Relative to such a release, that evoked by a further rise in D-glucose concentration or by non-glucidic nutrients was abnormally high in omega3-depleted rats, and restored to a normal level after of the intravenous injection of the omega3-rich medium-chain triglyceride-fish oil emulsion. Because the latter procedure failed to correct the perturbation of D-glucose metabolism in the islets of omega3-depleted rats, it is proposed that the anomalies in the secretory behaviour of islets in terms of their response to an increase in hexose concentration or non-nutrient secretagogues is mainly attributable to alteration in K+ and Ca2+ handling, as indeed recently documented in separate experiments.

Beef conjugated linoleic acid isomers reduce human cancer cell growth even when associated with other beef fatty acids.

Although many data are available concerning anticarcinogenic effects of industrial conjugated linoleic acid (CLA), few studies have reported the antitumour properties of CLA mixtures originating from ruminant products. The aim of the present study was to investigate the in vitro antiproliferative effects of beef CLA mixtures on breast, lung, colon, melanoma and ovarian human cancer cell lines. For this purpose, four fatty acid (FA) extracts prepared from beef lipid and varying in their CLA composition, their corresponding purified CLA-enriched fractions, and mixtures of pure synthetic CLA, the composition of which reproduced that of the four selected beef samples, were tested on cancer cell lines. Cancer cells were exposed for 48 h to medium containing 100 microm-FA and their proliferation was determined by quantifying cellular DNA content (Hoechst 33342 dye). Compared with cells incubated without FA, the number of cancer cells was reduced from 25 to 67 % (P<0.0001) following FA treatment. Antiproliferative effects of CLA mixtures varied in magnitude according to the source of FA, the CLA composition and the cell lines. CLA mixtures naturally present in beef inhibited the proliferation of human cancer cell lines, a high content in cis-trans isomers allowing the most important antiproliferative effect. Beef total FA exhibited a greater growth-inhibitory activity than their corresponding CLA-enriched fractions. These results suggested that either beef FA other than beef CLA could possess antiproliferative properties and/or the existence of complementary effects of non-conjugated FA and CLA, which could favour the antiproliferative properties of beef total FA.

Effects of specific CLA isomers on plasma fatty acid profile and expression of desaturases in humans.

Human studies suggest that CLA changes metabolism, possibly through effects on mRNA expression of desaturase and elongase enzymes. In this respect, differential effects of the two most common dietary CLA isomers, cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) CLA, have hardly been studied. We therefore gave 25 healthy, overweight men and women daily for 6 wk a drinkable dairy product containing 3 g of oil that was rich in oleic acid. For the next 18 wk, the control group (n = 7) continued to use this product, whereas the second (n = 9) and third groups (n = 9) received products with 3 g of purified c9,t11 CLA or t10,c12 CLA. For each gram of c9,t11 CLA consumed, the proportion in plasma phospholipids increased by 0.26%. For t10, c12 CLA, this value was 0.20%. The t10,c12 CLA isomer increased plasma TAG levels of conjugated 18:3, whereas c9,t11 CLA increased those of both conjugated 18:3 and 20:3. In plasma phospholipids, the delta9 desaturation index of 18:0 (18:1 n-9/18:0) was decreased by t10,c12 CLA (P= 0.03 for diet effects), and the delta6 desaturation index [(18:3n-6 + 20:3n-6)/18:2n-6] was decreased by both CLA isomers (P < 0.01 for diet effects). The delta5 desaturation index (20:4n-6/20:3n-6) and the delta9 desaturation index of 16:0 (16:1 n-7/16:0) were not affected. No effects were seen on mRNA expression of desaturases and elongase in peripheral blood mononuclear cells (PBMC). We therefore conclude that incorporation of c9,t11 and t10,c12 CLA into plasma lipids reflects dietary intakes. Compared with oleic acid, delta9 and delta6 desaturation indices in plasma phospholipids are decreased after consumption of c9,t11 or t10,c12 CLA. Effects on desaturation indices were, however, not reflected by changes at the transcriptional level for the various desaturases and elongase enzymes in PBMC.

Isomers of conjugated linoleic acid decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in post-prandial adult sedentary or trained Wistar rat.

The respective effects and interactions of supplementation with two conjugated linoleic acid (CLA) isomers and exercise on plasma metabolic profile, activity of lipogenic enzymes and cellularity in two adipose tissue sites, those of the liver and heart, were examined in adult Wistar rats. Rats that were either sedentary or exercise-trained by treadmill running were fed one of four diets: a diet without CLA; a diet with either 1% cis 9, trans 11 CLA or 1% trans 10, cis 12 CLA; or a mixture of both isomers (1% of each) for 6 weeks. We observed that the exercise decreased lipogenic enzyme activities in epididymal and perirenal adipose tissue. Plasma cholesterol, insulin, and leptin concentrations were lower in exercise-trained rats than in sedentary rats. The ingestion of either CLA mixture or the trans 10, cis 12 CLA increased lipogenic enzyme activities in epididymal tissue and more markedly in perirenal adipose tissue, especially in sedentary rats, and without affecting adipose tissue weight or cellularity. A similar effect of trans 10, cis 12 CLA was observed in regard to malic enzyme activity in the liver. In addition, this isomer decreased plasma lipid and urea concentrations and increased plasma 3-hydroxybutyrate levels. The ingestion of cis 9, trans 11 CLA increased fatty acid synthase activity in perirenal adipose tissue in sedentary rats and decreased plasma cholesterol and leptin concentrations. These results show that isomers of CLA decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in adult sedentary or exercise-trained rat, thus suggesting a stimulation of adipose tissue turnover.