Red meat and colorectal cancer: Nrf2-dependent antioxidant response contributes to the resistance of preneoplastic colon cells to fecal water of hemoglobin- and beef-fed rats.

Epidemiological studies have associated red meat intake with risk of colorectal cancer. Experimental studies explain this positive association by the oxidative properties of heme iron released in the colon. This latter is a potent catalyst for lipid peroxidation, resulting in the neoformation of deleterious aldehydes in the fecal water of heme-fed rats. The toxicity of fecal water of heme-fed rats was associated to such lipid peroxidation. This study demonstrated that fecal water of hemoglobin- and beef-fed rats preferentially induced apoptosis in mouse normal colon epithelial cells than in those carrying mutation on Apc (Adenomatous polyposis coli) gene, considered as preneoplastic. Highlighting the importance of lipid peroxidation and neoformation of secondary aldehydes like 4-hydroxy-2-nonenal (HNE), we optimized the depletion of carbonyl compounds in the fecal water which turned out to abolish the differential apoptosis in both cell lines. To explain the resistance of preneoplastic cells towards fecal water toxicity, we focused on Nrf2, known to be activated by aldehydes, including HNE. Fecal water activated Nrf2 in both cell lines, associated with the induction of Nrf2-target genes related to aldehydes detoxification. However, the antioxidant defense appeared to be higher in preneoplastic cells, favoring their survival, as evidenced by Nrf2 inactivation. Taken together, our results suggest that Nrf2-dependent antioxidant response was involved in the resistance of preneoplastic cells upon exposure to fecal water of hemoglobin- and beef-fed rats. This difference could explain the promoting effect of red meat and heme-enriched diet on colorectal cancer, by initiating positive selection of preneoplastic cells.

Is bisphenol S a safe substitute for bisphenol A in terms of metabolic function? An in vitro study.

As bisphenol A (BPA) has been shown to induce adverse effects on human health, especially through the activation of endocrine pathways, it is about to be withdrawn from the European market and replaced by analogues such as bisphenol S (BPS). However, toxicological data on BPS is scarce, and so it is necessary to evaluate the possible effects of this compound on human health. We compared the effect of BPA and BPS on obesity and hepatic steatosis processes using low doses in the same range as those found in the environment. Two in vitro models were used, the adipose cell line 3T3-L1 and HepG2 cells, representative of hepatic functions. We analyzed different parameters such as lipid and glucose uptakes, lipolysis, leptin production and the modulation of genes involved in lipid metabolism and energy balance. BPA and BPS induced an increase in the lipid content in the 3T3-L1 cell line and more moderately in the hepatic cells. We also observed a decrease in lipolysis after bisphenol treatment of adipocytes, but only BPS was involved in the increase in glucose uptake and leptin production. These latter effects could be linked to the modulation of SREBP-1c, PPARγ, aP2 and ERRα and γ genes after exposure to BPA, whereas BPS seems to target the PGC1α and the ERRγ genes. The findings suggest that both BPA and BPS could be involved in obesity and steatosis processes, but through two different metabolic pathways.

A dual model of normal vs isogenic Nrf2-depleted murine epithelial cells to explore oxidative stress involvement.

Cancer-derived cell lines are useful tools for studying cellular metabolism and xenobiotic toxicity, but they are not suitable for modeling the biological effects of food contaminants or natural biomolecules on healthy colonic epithelial cells in a normal genetic context. The toxicological properties of such compounds may rely on their oxidative properties. Therefore, it appears to be necessary to develop a dual-cell model in a normal genetic context that allows to define the importance of oxidative stress in the observed toxicity. Given that the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is considered to be the master regulator of antioxidant defenses, our aim was to develop a cellular model comparing normal and Nrf2-depleted isogenic cells to qualify oxidative stress-related toxicity. We generated these cells by using the CRISPR/Cas9 technique. Whole-genome sequencing enabled us to confirm that our cell lines were free of cancer-related mutations. We used 4-hydroxy-2-nonenal (HNE), a lipid peroxidation product closely related to oxidative stress, as a model molecule. Here we report significant differences between the two cell lines in glutathione levels, gene regulation, and cell viability after HNE treatment. The results support the ability of our dual-cell model to study the role of oxidative stress in xenobiotic toxicity.

Calcium-rich dairy matrix protects better than mineral calcium against colonic luminal haem-induced alterations in male rats.

The haemoglobin content in meat is consistently associated with an increased risk of colorectal cancer, whereas calcium may play a role as a chemopreventive agent. Using rodent models, calcium salts have been shown to prevent the promotion of haem-induced and red meat-induced colorectal carcinogenesis by limiting the bioavailability of the gut luminal haem iron. Therefore, this study aimed to compare impacts of dietary calcium provided as calcium salts or dairy matrix on gut homoeostasis perturbations by high haeminic or non-haeminic iron intakes. A 3-week intervention study was conducted using Fischer 344 rats. Compared to the ferric citrate-enriched diet, the haemoglobin-enriched diet led to increased faecal, mucosal, and urinary lipoperoxidation-related biomarkers, resulting from higher gut luminal haem iron bioavailability. This redox imbalance was associated to a dysbiosis of faecal microbiota. The addition of calcium to haemoglobin-enriched diets limited haem iron bioavailability and counteracted redox imbalance, with improved preventive efficacy when calcium was provided in dairy matrix. Data integration revealed correlations between haem-induced lipoperoxidation products and bacterial communities belonging to Peptococcaceae, Eubacterium coprostanoligenes group, and Bifidobacteriaceae. This integrated approach provides evidence of the benefits of dairy matrix as a dietary calcium vehicle to counteract the deleterious side-effects of meat consumption.

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats.

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth.

Urinary Metabolome Analysis Reveals Potential Microbiota Alteration and Electrophilic Burden Induced by High Red Meat Diet: Results from the French NutriNet-Santé Cohort and an In Vivo Intervention Study in Rats.

SCOPE: High red and processed meat consumption is associated with several adverse outcomes such as colorectal cancer and overall global mortality. However, the underlying mechanisms remain debated and need to be elucidated. METHODS AND RESULTS: Urinary untargeted Liquid Chromatography-Mass Spectrometry (LC-MS) metabolomics data from 240 subjects from the French cohort NutriNet-Santé are analyzed. Individuals are matched and divided into three groups according to their consumption of red and processed meat: high red and processed meat consumers, non-red and processed meat consumers, and at random group. Results are supported by a preclinical experiment where rats are fed either a high red meat or a control diet. Microbiota derived metabolites, in particular indoxyl sulfate and cinnamoylglycine, are found impacted by the high red meat diet in both studies, suggesting a modification of microbiota by the high red/processed meat diet. Rat microbiota sequencing analysis strengthens this observation. Although not evidenced in the human study, rat mercapturic acid profile concomitantly reveals an increased lipid peroxidation induced by high red meat diet. CONCLUSION: Novel microbiota metabolites are identified as red meat consumption potential biomarkers, suggesting a deleterious effect, which could partly explain the adverse effects associated with high red and processed meat consumption.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring.

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring. As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders. Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

Opuntia cladode powders inhibit adipogenesis in 3 T3-F442A adipocytes and a high-fat-diet rat model by modifying metabolic parameters and favouring faecal fat excretion.

BACKGROUND: Obesity is a major public health concern worldwide. A sedentary life and a nutritional transition to processed foods and high-calorie diets are contributing factors to obesity. The demand for nutraceutical foods, such as herbal weight-loss products, which offer the potential to counteract obesity, has consequently increased. We hypothesised that Opuntia cladodes consumption could assist weight management in an obesity prevention context. METHODS: This study was designed to explore the anti-adipogenic effects of lyophilised Opuntia cladode powders (OCP) in an in vitro cellular model for adipocyte differentiation and an in vivo high-fat-diet (HFD)-induced obesity rat model. Two OCP were tested, one from wild species O. streptacantha and the second from the most known species O. ficus-indica. RESULTS: Pre-adipocytes 3 T3-F442A were treated by OCP during the differentiation process by insulin. OCP treatment impaired the differentiation in adipocytes, as supported by the decreased triglyceride content and a low glucose uptake, which remained comparable to that observed in undifferentiated controls, suggesting that an anti-adipogenic effect was exerted by OCP. Sprague-Dawley rats were fed with a normal or HFD, supplemented or not with OCP for 8 weeks. OCP treatment slightly reduced body weight gain, liver and abdominal fat weights, improved some obesity-related metabolic parameters and increased triglyceride excretion in the faeces. Taken together, these results showed that OCP might contribute to reduce adipogenesis and fat storage in a HFD context, notably by promoting the faecal excretion of fats. CONCLUSIONS: Opuntia cladodes may be used as a dietary supplement or potential therapeutic agent in diet-based therapies for weight management to prevent obesity.

Haem iron reshapes colonic luminal environment: impact on mucosal homeostasis and microbiome through aldehyde formation.

BACKGROUND: The World Health Organization classified processed and red meat consumption as "carcinogenic" and "probably carcinogenic", respectively, to humans. Haem iron from meat plays a role in the promotion of colorectal cancer in rodent models, in association with enhanced luminal lipoperoxidation and subsequent formation of aldehydes. Here, we investigated the short-term effects of this haem-induced lipoperoxidation on mucosal and luminal gut homeostasis including microbiome in F344 male rats fed with a haem-enriched diet (1.5 µmol/g) 14-21 days. RESULTS: Changes in permeability, inflammation, and genotoxicity observed in the mucosal colonic barrier correlated with luminal haem and lipoperoxidation markers. Trapping of luminal haem-induced aldehydes normalised cellular genotoxicity, permeability, and ROS formation on a colon epithelial cell line. Addition of calcium carbonate (2%) to the haem-enriched diet allowed the luminal haem to be trapped in vivo and counteracted these haem-induced physiological traits. Similar covariations of faecal metabolites and bacterial taxa according to haem-induced lipoperoxidation were identified. CONCLUSIONS: This integrated approach provides an overview of haem-induced modulations of the main actors in the colonic barrier. All alterations were closely linked to haem-induced lipoperoxidation, which is associated with red meat-induced colorectal cancer risk.

Lipid metabolism in human endothelial cells.

Although lipids are largely involved in cardiovascular physiopathology, the lipid metabolism in endothelial cells remains largely unknown. Human umbilical vein endothelial cells (HUVECs) were used to investigate the metabolism of complex lipids. The membrane phospholipid homeostasis results from both de novo synthesis and remodelling that ensures the fine tuning of the phospholipid fatty acid composition. Using [(3)H]-glycerol and phosphoderivatives we showed the efficiency of glycerolipid synthesis from glycerol (0.9 nmol h(-1) mg proteins(-1)), but not from its phosphorylated form suggesting the requirement of a functional glycerol kinase in HUVECs. Conversely, the synthesis of triacylglycerols was very low (less than 5% of phospholipid synthesis). The incorporation rate of fatty acids into phospholipids showed that there is a specific fate for each fatty acid in respect to its chain length and saturation level. Moreover in steady state condition, increasing the long chain omega3 polyunsaturated fatty acids in the medium resulted in an increased polyunsaturated/saturated ratio in phospholipids (from 0.42 to 0.63). [(14)C]O(2) was produced form either [(14)C]-glucose or [(14)C]-palmitate indicating the functionality of the oxidation pathways, although beta-oxidation was less efficient than glucose oxidation. The endothelial cell lipid metabolism involves conventional pathways, with functional rates largely slower than in hepatocytes or in cardiomyocytes.

Opuntia spp.: Characterization and Benefits in Chronic Diseases.

Opuntia species have been used for centuries as food resources and in traditional folk medicine for their nutritional properties and their benefit in chronic diseases, particularly diabetes, obesity, cardiovascular diseases, and cancer. These plants are largely distributed in America, Africa, and the Mediterranean basin. Opuntia spp. have great economic potential because they grow in arid and desert areas, and O. ficus-indica, the domesticated O. species, is used as a nutritional and pharmaceutical agent in various dietary and value-added products. Though differences in the phytochemical composition exist between wild and domesticated (O. ficus-indica) Opuntia spp., all Opuntia vegetatives (pear, roots, cladodes, seeds, and juice) exhibit beneficial properties mainly resulting from their high content in antioxidants (flavonoids, ascorbate), pigments (carotenoids, betalains), and phenolic acids. Other phytochemical components (biopeptides, soluble fibers) have been characterized and contribute to the medicinal properties of Opuntia spp. The biological properties of Opuntia spp. have been investigated on cellular and animal models and in clinical trials in humans, allowing characterization and clarification of the protective effect of Opuntia-enriched diets in chronic diseases. This review is an update on the phytochemical composition and biological properties of Opuntia spp. and their potential interest in medicine.

Regulation of intermediary metabolism in rat cardiac myocyte by extracellular glycerol.

In the human heart, although all substrates compete for energy production, fatty acids (FA) represent the main substrate for ATP production. In the healthy heart, a balance between FA and carbohydrate utilization ensures that energy supply matches demand. This study was carried out to evaluate, in a model of spontaneously beating neonatal rat cardiomyocytes in culture, the hypothesis that glycerol could play a central role in the metabolic control of the routes involving long chain FAs and may then affect the balance between beta-oxidation and glucose oxidation. The intracellular-free glycerol significantly increased with extracellular glycerol concentration (0 to 660 microM). The synthesis of phospholipids was significantly increased in parallel with both extracellular glycerol (1.5 and 14.8 nmol glycerol/mg protein, at 82 and 660 microM of extracellular glycerol, respectively). The oxidation of glycerol increased proportionally to extracellular glycerol concentration (from 1 to 3 nmol glycerol/mg protein, at 82 microM and 660 microM extracellular glycerol, respectively, P<0.001). At its maximum, this oxidation represented 15% of the glucose oxidation, which was not affected by glycerol extracellular supply or intracellular availability. Conversely, extracellular glycerol significantly reduced the palmitate oxidation above (-47% at 660 microM glycerol), but not octanoate oxidation. Investigations on the mechanism of the decreased palmitate oxidation reveals a glycerol-dependent increase in malonyl-CoA associated with a significant decrease in CPT-1 activity which accounts for the difference between palmitate and octanoate. These results clearly demonstrate the importance of glycerol in regulating the cardiac metabolic pathways and energy balance.

The environmental carcinogen benzo[a]pyrene induces a Warburg-like metabolic reprogramming dependent on NHE1 and associated with cell survival.

Cancer cells display alterations in many cellular processes. One core hallmark of cancer is the Warburg effect which is a glycolytic reprogramming that allows cells to survive and proliferate. Although the contributions of environmental contaminants to cancer development are widely accepted, the underlying mechanisms have to be clarified. Benzo[a]pyrene (B[a]P), the prototype of polycyclic aromatic hydrocarbons, exhibits genotoxic and carcinogenic effects, and it is a human carcinogen according to the International Agency for Research on Cancer. In addition to triggering apoptotic signals, B[a]P may induce survival signals, both of which are likely to be involved in cancer promotion. We previously suggested that B[a]P-induced mitochondrial dysfunctions, especially membrane hyperpolarization, might trigger cell survival signaling in rat hepatic epithelial F258 cells. Here, we further characterized these dysfunctions by focusing on energy metabolism. We found that B[a]P promoted a metabolic reprogramming. Cell respiration decreased and lactate production increased. These changes were associated with alterations in the tricarboxylic acid cycle which likely involve a dysfunction of the mitochondrial complex II. The glycolytic shift relied on activation of the Na(+)/H(+) exchanger 1 (NHE1) and appeared to be a key feature in B[a]P-induced cell survival related to changes in cell phenotype (epithelial-to-mesenchymal transition and cell migration).

Dietary polyunsaturated fatty acids and heme iron induce oxidative stress biomarkers and a cancer promoting environment in the colon of rats.

The end products of polyunsaturated fatty acid (PUFA) peroxidation, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE), and isoprostanes (8-iso-PGF2α), are widely used as systemic lipid oxidation/oxidative stress biomarkers. However, some of these compounds have also a dietary origin. Thus, replacing dietary saturated fat by PUFAs would improve health but could also increase the formation of such compounds, especially in the case of a pro-oxidant/antioxidant imbalanced diet. Hence, the possible impact of dietary fatty acids and pro-oxidant compounds was studied in rats given diets allowing comparison of the effects of heme iron vs. ferric citrate and of ω-6- vs. ω-3-rich oil on the level of lipid peroxidation/oxidative stress biomarkers. Rats given a heme iron-rich diet without PUFA were used as controls. The results obtained have shown that MDA and the major urinary metabolite of HNE (the mercapturic acid of dihydroxynonane, DHN-MA) were highly dependent on the dietary factors tested, while 8-iso-PGF2α was modestly but significantly affected. Intestinal inflammation and tissue fatty acid composition were checked in parallel and could only explain the differences we observed to a limited extent. Thus, the differences in biomarkers were attributed to the formation of lipid oxidation compounds in food or during digestion, their intestinal absorption, and their excretion into urine. Moreover, fecal extracts from the rats fed the heme iron or fish oil diets were highly toxic for immortalized mouse colon cells. Such toxicity can eventually lead to promotion of colorectal carcinogenesis, supporting the epidemiological findings between red meat intake and colorectal cancer risk. Therefore, the analysis of these biomarkers of lipid peroxidation/oxidative stress in urine should be used with caution when dietary factors are not well controlled, while control of their possible dietary intake is needed also because of their pro-inflammatory, toxic, and even cocarcinogenic effects.

Comparative study of bisphenol A and its analogue bisphenol S on human hepatic cells: a focus on their potential involvement in nonalcoholic fatty liver disease.

For several decades, people have been in contact with bisphenol A (BPA) primarily through their diet. Nowadays it is gradually replaced by an analogue, bisphenol S (BPS). In this study, we compared the effects of these two bisphenols in parallel with the positive control diethylstilbestrol (DES) on different hepatocyte cell lines. Using a cellular impedance system we have shown that BPS is less cytotoxic than BPA in acute and chronic conditions. We have also demonstrated that, contrary to BPA, BPS is not able to induce an increase in intracellular lipid and does not activate the PXR receptor which is known to be involved in part, in this process. In parallel, it failed to modulate the expression of CYP3A4 and CYP2B6, the drug transporter ABCB1 and other lipid metabolism genes (FASN, PLIN). However, it appears to have a weak effect on GSTA4 protein expression and on the Erk1/2 pathway. In conclusion, in contrast to BPA, BPS does not appear to induce the metabolic syndrome that may lead to non-alcoholic fatty liver disease (NAFLD), in vitro. Although we have to pay special attention to BPS, its use could be less dangerous concerning this toxicological endpoint for human health.

Low concentrations of bisphenol A induce lipid accumulation mediated by the production of reactive oxygen species in the mitochondria of HepG2 cells.

Bisphenol A (BPA) is an endocrine-disrupting chemical that leaches from polycarbonate plastics that consequently leads to low-dose human exposure. In addition to its known xenoendocrine action, BPA exerts a wide variety of metabolic effects, but no data are available on its actions on the functions of liver mitochondrial. To assess these effects, HepG2 cells were exposed to BPA (10(-4)-10(-12)M) and physiological parameters were measured by flow cytometry. We demonstrated a significant mitochondrial dysfunction including ROS production, ΔΨ(M) hyperpolarization, lipid accumulation, lipoperoxidation and the release of pro-inflammatory cytokines. In conclusion, we showed that low concentrations of BPA promote lipid accumulation in hepatic cells triggered by disturbances in mitochondrial function, alterations in lipid metabolism and by inflammation that can therefore contribute to steatosis.

Extracellular glycerol regulates the cardiac energy balance in a working rat heart model.

We reported previously that glycerol is a substrate for energy production in cardiomyocytes. Increasing glycerol availability results in increased glycerol uptake and its involvement in complex lipid biosynthesis and energy production. This study evaluated the relationship between glycerol supply, energy demand, and intermediary metabolism leading to energy production. The work was performed on isolated rat heart perfused in the working mode. Glycerol concentrations modeled the fasting (0.33 mM) and fed (3.33 mM) states. Cardiac energy demand was modeled by increasing heart rate from 350 to 450 beats/min (bpm). Increasing glycerol supply increased glycerol uptake from 1.4 (350 bpm) to 3.8 (450 bpm) and from 9.7 (350 bpm) to 34.2 (450 bpm) micro mol glycerol/heart in 30 min at 0.33 and 3.33 mM glycerol, respectively. At low glycerol supply, increasing heart rate did not influence the complex lipid synthesis. Conversely, high glycerol concentration increased the complex lipid synthesis by 5- and 30-fold at 350 and 450 bpm, respectively. Increasing glycerol supply and heart rate significantly increased glycerol oxidation rate. Moreover, increasing glycerol supply did not affect glucose oxidation but increased palmitate uptake and significantly decreased its beta-oxidation. Physiological concentrations of glycerol contribute to the cardiac intermediary metabolism, both for energy production and glycerolipid synthesis. Increasing energy demand enhances the requirement and use of glycerol. Glycerol contributes to the regulation of cardiac metabolism and energy balance, mainly by decreasing the contribution of fatty acid oxidation, and may thus represent a new factor in cardiac protection through the reduction of oxygen demand.

Aortic banding in rat as a model to investigate malnutrition associated with heart failure.

Heart failure is a severe pathology, which has displayed a dramatic increase in the occurrence of patients with chronic heart disease in developed countries, as a result of increases in the population's average age and in survival time. This pathology is associated with severe malnutrition, which worsens the prognosis. Although the cachexia associated with chronic heart failure is a well-known complication, there is no reference animal model of malnutrition related to heart failure. This study was designed to evaluate the nutritional status of rats in a model of loss of cardiac function obtained by ascending aortic banding. Cardiac overload led to the development of cardiac hypertrophy, which decompensates to heart failure, with increased brain natriuretic peptide levels. The rats displayed hepatic dysfunction and an associated renal hypotrophy and renal failure, evidenced by the alteration in renal function markers such as citrullinemia, creatininemia, and uremia. Malnutrition has been evidenced by the alteration of protein and amino acid metabolism. A muscular atrophy with decreased protein content and increased amino acid concentrations in both plasma and muscle was observed. These rats with heart failure displayed a multiorgan failure and malnutrition, which reflected the clinical situation of human chronic heart failure.

Dietary n-3 PUFAs affect the blood pressure rise and cardiac impairments in a hyperinsulinemia rat model in vivo.

The cardiovascular consequences of eicosapentaenoic acid (EPA)- and docosahexaenoic acid (DHA)-specific intake were evaluated in vivo in a hyperinsulinemia (HI) model induced by dietary fructose intake. Wistar rats were fed a diet containing (or not for control) either EPA or DHA. The rise in blood pressure (BP), heart rate, and ECG were continuously monitored using an intra-abdominal telemetry system. The myocardial phospholipid fatty acid profile was significantly affected by DHA intake but less by EPA intake. The data indicated a reduced rise in BP in both DHA and EPA HI groups compared with controls. This result was confirmed by tail-cuff measurement after 5 wk [133.3 +/- 1.67 and 142.5 +/- 1.12 mmHg in n-3 polyunsaturated fatty acid (PUFA) and control groups, respectively], whereas n-3 PUFA did not affect BP in non-HI rats (116.3 +/- 3.33 mmHg). The heart rate was lower in the HI DHA group than in the other two dietary HI groups. Moreover, DHA induced a significantly shorter QT interval. It is concluded that the cardioactive component of fish oils is DHA through a mechanism that may involve the cardiac adrenergic system.

Prevention of heart failure in rats by trimetazidine treatment: a consequence of accelerated phospholipid turnover?

Heart failure is known for alteration of cardiac catecholamine responsiveness involving adrenergic receptor (AR) down-regulation. Trimetazidine, a metabolically active anti-ischemic drug, accelerates the turnover of phospholipids. The present study evaluated the consequences of trimetazidine treatment (supposed to increase phospholipid synthesis) on AR in heart failure in rats. In control rats, trimetazidine (7.5 mg/day supplied in the diet) induced after 8 weeks a significant increase in both beta- (+54%) and alpha-AR (+30%) density, although after 12 weeks, the receptor density was normalized. Heart failure was obtained by ascending aortic banding. These heart failure rats developed a severe cardiac hypertrophy, mainly affecting the left ventricle, which was significantly reduced in the trimetazidine-treated group. The plasma level of brain natriuretic peptide (BNP), a marker of heart failure severity, was significantly increased in the heart failure group as compared with the sham group (900 and 1200% after 8 and 12 weeks, respectively). In the trimetazidine-treated group, the plasma BNP increase was significantly lower. The development of heart failure was associated with a decrease in beta- and alpha-AR sites (-23 and -36% versus sham, respectively) after 8 weeks and continued to decrease after 12 weeks (-37 and -48% versus sham, respectively). This down-regulation was prevented by trimetazidine without alteration in affinity. These results suggest that trimetazidine prevents AR desensitization and cardiac hypertrophy, in a pressure-overload model of heart failure. This cytoprotection suggests that membrane homeostasis preservation may be considered as a therapeutic target in the treatment of heart failure.