Induction of lipid oxidation by polyunsaturated fatty acids of marine origin in small intestine of mice fed a high-fat diet

Background. Dietary polyunsaturated fatty acids (PUFA), in particular the long chain marine fatty acids docosahexaenoic (DHA) and eicosapentaenoic (EPA), are linked to many health benefits in humans and in animal models. Little is known of the molecular response to DHA and EPA of the small intestine, and the potential contribution of this organ to the beneficial effects of these fatty acids. Here, we assessed gene expression changes induced by DHA and EPA in the wildtype C57BL/6J murine small intestine using whole genome microarrays and functionally characterized the most prominent biological process. Results. The main biological process affected based on gene expression analysis was lipid metabolism. Fatty acid uptake, peroxisomal and mitochondrial beta-oxidation, and omega-oxidation of fatty acids were all increased. Quantitative real time PCR, and -in a second animal experiment- intestinal fatty acid oxidation measurements confirmed significant gene expression differences and showed in a dose-dependent manner significant changes at biological functional level. Furthermore, no major changes in the expression of lipid metabolism genes were observed in the colon. Conclusion. We show that marine n-3 fatty acids regulate small intestinal gene expression and increase fatty acid oxidation. Since this organ contributes significantly to whole organism energy use, this effect on the small intestine may well contribute to the beneficial physiological effects of marine PUFAs under conditions that will normally lead to development of obesity, insulin resistance and diabete

Alcohol consumption, alcohol dehydrogenase 3 polymorphism, and colorectal adenomas.

Alcohol is a probable risk factor with regard to colorectal neoplasm and is metabolized to the carcinogen acetaldehyde by the genetically polymorphic alcohol dehydrogenase 3 (ADH3) enzyme. We evaluated whether the association between alcohol and colorectal adenomas is modified by ADH3 polymorphism. We recruited 433 cases with adenomatous polyps and 436 polyp-free controls among Caucasians undergoing endoscopy between 1995 and 2000. Frequency and amount of habitual alcohol consumption were assessed by beverage type, using a validated self-administered food frequency questionnaire. All participants provided blood for genotyping of ADH3. Multivariate analyses adjusting for gender, age, and indication for endoscopy showed that alcohol increased the risk of colorectal adenomas among women [odds ratio (OR), 1.8; 95% confidence interval (CI), 1.0-3.2, >/=10 versus 21 drinks/week (OR, 1.8; 95% CI, 0.9-3.8, compared with men drinking < 1 drink/week). Among subjects in the highest tertile of alcohol consumption, those with the ADH3*1/*1 genotype were at higher risk (OR, 1.8; 95% CI, 1.0-3.1) than those with other ADH3 genotypes (OR, 1.2; 95% CI, 0.7-1.9) when compared with those in the lowest tertile with ADH3*1/*2 or ADH3*2/*2 genotypes. In conclusion, our findings are consistent with results of other studies, suggesting that alcohol consumption elevates the risk of adenomatous colorectal polyps. ADH3 polymorphism may modify the association between alcohol consumption and colorectal adenomas

The effect of insulin, glucose and rosiglitazone on mouse 3T3-L1 mature adipocytes gene expression

Obesity is associated with insulin resistance and type 2 diabetes, implying a role for adipose tissue in the etiology of these disorders. We used cDNA microarrays to obtain expression profiles of adipocyte by the treatment of insulin and anti-diabetic drug rosiglitazone at both high and low glucose level. Mouse 3T3-L1 mature adipocytes were treated 2 days 1) with or without 1 µM insulin at low and high glucose level, 2) with or without 0.5 μM rosiglitazone at low and high glucose and insulin level. 1) The comparison between the insulin and non-insulin treatment at the same glucose level showed minor changes in the transcriptome. The expressions of some processing enzymes for extracellular matrix components were regulated by insulin. 2) Transcriptome data indicates that an altered energy metabolism is induced by rosiglitazone in mature adipocytes. In addition, rosiglitazone represses adipokine expression, except adiponectin and ApoE. Moreover, transcriptome changes indicate that a general repression of secreted protein encoding genes occurs

The effect of insulin, glucose and rosiglitazone on mouse 3T3-L1 mature adipocytes gene expression

Obesity is associated with insulin resistance and type 2 diabetes, implying a role for adipose tissue in the etiology of these disorders. We used cDNA microarrays to obtain expression profiles of adipocyte by the treatment of insulin and anti-diabetic drug rosiglitazone at both high and low glucose level. Mouse 3T3-L1 mature adipocytes were treated 2 days 1) with or without 1 µM insulin at low and high glucose level, 2) with or without 0.5 μM rosiglitazone at low and high glucose and insulin level. 1) The comparison between the insulin and non-insulin treatment at the same glucose level showed minor changes in the transcriptome. The expressions of some processing enzymes for extracellular matrix components were regulated by insulin. 2) Transcriptome data indicates that an altered energy metabolism is induced by rosiglitazone in mature adipocytes. In addition, rosiglitazone represses adipokine expression, except adiponectin and ApoE. Moreover, transcriptome changes indicate that a general repression of secreted protein encoding genes occurs

Beta-carotene and the application of transcriptomics in risk–benefit evaluation of natural dietary components

AbstractBeta-carotene is a natural food component that is present in fruits and vegetables and is also used as a food colorant and a supplement. Beta-carotene is an anti-oxidant and a source of vitamin A. It is endowed with health beneficial properties, but a number of studies showed that with high intakes it may increase the risk for lung cancer in at risk individuals (heavy smokers, asbestos workers and alcohol users). To establish the window of benefit, it is necessary to identify early markers of effect and to obtain insight in the mechanism of action of beta-carotene, in the absence and presence of environmental risk factors. Genomics technologies are well suited to dissect the mechanisms of action and identify the markers of effect. Human cell lines can be used to analyse the effects of beta-carotene, but exposure studies with beta-carotene show that cell lines display a widely variant behaviour, which hampers translation to the in vivo situation in humans. Alternatively, animal studies can be used. Especially the ferret seems to be a good model, but little sequence information of this species is available. However, heterologous hybridization on human cDNA seems possible and provides and a new tool for molecular analysis of health effects of beta-carotene

Muscle Involvement in Preservation of Metabolic Flexibility by Treatment using n-3 PUFA or Rosiglitazone in Dietary-Obese Mice

Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients

Muscle Involvement in Preservation of Metabolic Flexibility by Treatment using n-3 PUFA or Rosiglitazone in Dietary-Obese Mice

Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients

Different lipid forms of omega-3 and their effect on small intestine in mice

Omega - 3 fatty acids of marine origin exert beneficial effects on lipid metabolism and can protect against insulin resistance in high fat diet (HFD)-fed animals. Simultaneously, recent studies showed that different lipid forms could have numerous consequences regarding the regulation of energy balance, nutrient absorption, and substrate metabolism. Indeed, when omega-3 was provided as triglycerides (TG, i.e. fish oil), it induced dose-dependently the expression of genes involved in lipid metabolism as well as fatty acid oxidation in small intestine of C57BL/6 mice fed various HFDs. As the underlying mechanism(s) explaining the differences in EPA/DHA bioavailability among various lipid forms of Omega-3 is not entirely clear, we performed a mouse study (n=8 per group) using purified HFDs with control HFD based on corn oil (cHF) and part of the lipids were replaced by omega-3 fish lipids in different forms: as either TG (cHF-F), marine phospholipids (PL; Krill oil, given at two different doses Krill-low (Krill-L) and Krill-high (Krill-H)), and as wax esters in the extract from the zooplankton Calanus finmarchicus (Calanus oil CAL-L representing same omega-3 levels as Krill-L diet). As a healthy control we fed a subset of mice standard chow (STD). All mice were fed their diet for 8 weeks and after sacrifice, whole small intestine was isolated, frozen and used for RNA isolation and microarray gene expression analysis using 8x60K Agilent arrays. Results showed that PL-H versus control cHFc induced specifically metabolic lipid pathways, while TG and PL-L mainly affected cytoskeleton regulation

Muscle Involvement in Preservation of Metabolic Flexibility by Treatment using n-3 PUFA or Rosiglitazone in Dietary-Obese Mice

Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients