Conjugated linoleic acid activates peroxisome proliferator-activated receptor alpha and beta subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats

Dietary conjugated linoleic acid supplementation alters skeletal muscle mitochondria and antioxidant status in young horses

Conjugated linoleic acid (CLA) improves oxidative stress and mitochondrial biogenesis in various species but has not been thoroughly investigated in horses. We collected blood and muscle samples from lightly exercising horses before and 6 and 12 wk after receiving either soybean oil (CON; n = 5) or CLA (CLA; n = 5) supplementation. Samples were analyzed for markers of mitochondrial characteristics, antioxidant status, oxidative stress, and muscle damage. Data were analyzed using a linear model with repeated measures. In the triceps brachii (TB), citrate synthase (CS) activity was higher in CON than CLA horses (P = 0.003) but was unaffected by diet in the gluteus medius (GM). Integrative (relative to mg protein) cytochrome c oxidase (CCO) activity was higher in TB than the GM (P < 0.0001), while intrinsic (relative to CS) CCO was lower in the TB than the GM (P = 0.02) and tended to be lower in CON than CLA horses (P = 0.06). Neither CS nor integrative CCO activities were affected by time. In the GM, superoxide dismutase activity tended to increase in CON through week 12 (P = 0.10). Over both muscle groups, glutathione peroxidase activity tended to be higher in CON compared with CLA at week 12 (P = 0.06). Malondialdehyde was higher in the TB than the GM (P = 0.0004) but was unaffected by diet, while serum creatine kinase activity tended to be lower in CLA than CON horses (P = 0.07). These results suggest that CLA supplementation may lead to mitochondrial adaptations and prevent myofiber perturbation in skeletal muscle of young, lightly exercised horses.

Nutrigenomic point of view on effects and mechanisms of action of ruminant trans fatty acids on insulin resistance and type 2 diabetes

Evidence from observational studies suggests beneficial effects of ruminant trans fatty acids (rTFA) on insulin resistance (IR) and type 2 diabetes (T2D). However, beneficial effects of rTFA are not always observed in cell, animal, and human studies. This narrative review presents potential mechanisms of action of rTFA using nutrigenomics and microRNA results in an integrative model. In addition, the review presents factors, including measures of IR and T2D, dose and duration of studies, as well as health status, ethnicity, and genotypes of subjects, that may help explain the heterogeneity in response to rTFA supplementation. Future studies should consider these factors, as well as research in nutritional genomics, to better understand the effects of rTFA on IR and T2D.

The role of various peroxisome proliferator-activated receptors and their ligands in clinical practice

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors involved in several physiological processes including modulation of cellular differentiation, development, metabolism of carbohydrates, lipids, proteins, and tumorigenesis. The aim of this review is to examine how different PPAR ligands act, and discuss their use in clinical practice. PPAR ligands have a lot of effects and applications in clinical practice. Some PPAR ligands such as fibrates (PPAR-α ligands) are currently used for the treatment of dyslipidemia, while pioglitazone and rosiglitazone (PPAR-γ ligands) are anti-diabetic and insulin-sensitizing agents. Regarding new generation drugs, acting on both α/γ, β/δ, or α/δ receptors simultaneously, preliminary data on PPAR-α/γ dual agonists revealed a positive effect on lipid profile, blood pressure, atherosclerosis, inflammation, and anti-coagulant effects, while the overexpression of PPAR-β/δ seems to prevent obesity and to decrease lipid storage in cardiac cells. Finally, PPAR-α/δ dual agonist induces resolution of nonalcoholic steatohepatitis without fibrosis worsening.

Modulation of inflammation and immunity by dietary conjugated linoleic acid

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid. This family of polyunsaturated fatty acids has drawn significant attention in the last three decades for its variety of biologically beneficial properties and health effects. CLA has been shown to exert various potent protective functions such as anti-inflammatory, anticarcinogenic, antiadipogenic, antidiabetic and antihypertensive properties in animal models of disease. Therefore, CLA represents a nutritional avenue to prevent lifestyle diseases or metabolic syndrome. Initially, the overall effects of CLA were thought to be the result of interactions between its two major isomers: cis-9, trans-11 and trans-10, cis-12. However, later evidence suggests that such physiological effects of CLA might be different between the isomers: t-10, c-12-CLA is thought to be anticarcinogenic, antiobesity and antidiabetic, whereas c-9, t-11-CLA is mainly anti-inflammatory. Although preclinical data support a benefit of CLA supplementation, human clinical findings have yet to show definitive evidence of a positive effect. The purpose of this review is to comprehensively summarize the mechanisms of action and anti-inflammatory properties of dietary CLA supplementation and evaluate the potential uses of CLA in human health and disease.

Dietary conjugated linoleic acid alters oxidative stability and alleviates plasma cholesterol content in meat of broiler chickens

This study was conducted to investigate the effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipoprotein content, lipid peroxidation, and meat colour of broiler chickens. A total of 180 broiler chickens were allocated to 3 dietary treatments (0, 2.5, and 5% Lutrell) and given a standard broiler starter diet and finisher diet. Body weight of chickens and feed intake were recorded weekly. After slaughter, the breast meat was aged at 4 °C for 0, 3, and 6 days. The fatty acid composition was measured in the breast meat. Body weight (BW) and feed efficiency were decreased by dietary CLA level (P < 0.05). Chicken fed with 2.5% Lutrell had the highest feed intake compared to the control (CON) group. The total CLA increased significantly (P < 0.05) in breast meat from birds supplemented with CLA. Propensity for lipid peroxidation was significantly higher after 6 days of meat storage (P < 0.05) and the redness in chicken breast meat was lower in CLA-fed birds (P < 0.05). It is also notable that a 5% Lutrell supplementation decreased the plasma total cholesterol (TC), low density protein (LDL), and HDL (high-density lipoprotein)/LDL ratio in chickens (P < 0.05).

c9,t11-Conjugated linoleic acid ameliorates steatosis by modulating mitochondrial uncoupling and Nrf2 pathway

Oxidative stress, hepatic steatosis, and mitochondrial dysfunction are key pathophysiological features of nonalcoholic fatty liver disease. A conjugated linoleic acid (CLA) mixture of cis9,trans11 (9,11-CLA) and trans10,cis12 (10,12-CLA) isomers enhanced the antioxidant/detoxifying mechanism via the activation of nuclear factor E2-related factor-2 (Nrf2) and improved mitochondrial function, but less is known about the actions of specific isomers. The differential ability of individual CLA isomers to modulate these pathways was explored in Wistar rats fed for 4 weeks with a lard-based high-fat diet (L) or with control diet (CD), and, within each dietary treatment, two subgroups were daily administered with 9,11-CLA or 10,12-CLA (30 mg/day). The 9,11-CLA, but not 10,12-CLA, supplementation to CD rats improves the GSH/GSSG ratio in the liver, mitochondrial functions, and Nrf2 activity. Histological examination reveals a reduction of steatosis in L-fed rats supplemented with both CLA isomers, but 9,11-CLA downregulated plasma concentrations of proinflammatory markers, mitochondrial dysfunction, and oxidative stress markers in liver more efficiently than in 10,12-CLA treatment. The present study demonstrates the higher protective effect of 9,11-CLA against diet-induced pro-oxidant and proinflammatory signs and suggests that these effects are determined, at least in part, by its ability to activate the Nrf2 pathway and to improve the mitochondrial functioning and biogenesis.

Perfluorooctane sulfonate induces neuronal and oligodendrocytic differentiation in neural stem cells and alters the expression of PPARγ in vitro and in vivo

Perfluorinated compounds are ubiquitous chemicals of major concern for their potential adverse effects on the human population. We have used primary rat embryonic neural stem cells (NSCs) to study the effects of perfluorooctane sulfonate (PFOS) on the process of NSC spontaneous differentiation. Upon removal of basic fibroblast growth factor, NSCs were exposed to nanomolar concentrations of PFOS for 48 h, and then allowed to differentiate for additional 5 days. Exposure to 25 or 50 nM concentration resulted in a lower number of proliferating cells and a higher number of neurite-bearing TuJ1-positive cells, indicating an increase in neuronal differentiation. Exposure to 50 nM also significantly increased the number of CNPase-positive cells, pointing to facilitation of oligodendrocytic differentiation. PPAR genes have been shown to be involved in PFOS toxicity. By q-PCR we detected an upregulation of PPARγ with no changes in PPARα or PPARδ genes. One of the downstream targets of PPARs, the mitochondrial uncoupling protein 2 (UCP2) was also upregulated. The number of TuJ1- and CNPase-positive cells increased after exposure to PPARγ agonist rosiglitazone (RGZ, 3 μM) and decreased after pre-incubation with the PPARγ antagonist GW9662 (5 μM). RGZ also upregulated the expression of PPARγ and UCP2 genes. Meanwhile GW9662 abolished the UCP2 upregulation and decreased Ca²⁺ activity induced by PFOS. Interestingly, a significantly higher expression of PPARγ and UCP3 genes was also detected in mouse neonatal brain after prenatal exposure to PFOS. These data suggest that PPARγ plays a role in the alteration of spontaneous differentiation of NSCs induced by nanomolar concentrations of PFOS.

t-10, c-12 CLA dietary supplementation inhibits atherosclerotic lesion development despite adverse cardiovascular and hepatic metabolic marker profiles

Animal and human studies have indicated that fatty acids such as the conjugated linoleic acids (CLA) found in milk could potentially alter the risk of developing metabolic disorders including diabetes and cardiovascular disease (CVD). Using susceptible rodent models (apoE^−/− and LDLr^−/− mice) we investigated the interrelationship between mouse strain, dietary conjugated linoleic acids and metabolic markers of CVD. Despite an adverse metabolic risk profile, atherosclerosis (measured directly by lesion area), was significantly reduced with t-10, c-12 CLA and mixed isomer CLA (Mix) supplementation in both apoE^−/− (p<0.05, n = 11) and LDLr^−/− mice (p<0.01, n = 10). Principal component analysis was utilized to delineate the influence of multiple plasma and tissue metabolites on the development of atherosclerosis. Group clustering by dietary supplementation was evident, with the t-10, c-12 CLA supplemented animals having distinct patterns, suggestive of hepatic insulin resistance, regardless of mouse strain. The effect of CLA supplementation on hepatic lipid and fatty acid composition was explored in the LDLr^−/− strain. Dietary supplementation with t-10, c-12 CLA significantly increased liver weight (p<0.05, n = 10), triglyceride (p<0.01, n = 10) and cholesterol ester content (p<0.01, n = 10). Furthermore, t-10, c-12 CLA also increased the ratio of 18∶1 to 18∶0 fatty acid in the liver suggesting an increase in the activity of stearoyl-CoA desaturase. Changes in plasma adiponectin and liver weight with t-10, c-12 CLA supplementation were evident within 3 weeks of initiation of the diet. These observations provide evidence that the individual CLA isomers have divergent mechanisms of action and that t-10, c-12 CLA rapidly changes plasma and liver markers of metabolic syndrome, despite evidence of reduction in atherosclerosis.

Free radical scavenging activity of conjugated linoleic acid as single or mixed isomers

CONTEXT

Conjugated linoleic acids (CLAs) are a mixture of positional and geometric isomers of linoleic acid (LA) and believed to have many positive biological activities.

OBJECTIVE

The present study was undertaken to assess the antioxidant activity of cis-9, trans-11 and trans-10, cis-12 as single or mixed CLA isomers at two ratios, 1:6 and 1:13 (trans-10, cis-12/cis-9, trans-11).

MATERIALS AND METHODS

A microplate reader was used to determine the free radical scavenging properties of CLAs against DPPH radical in ethanol.

RESULTS

The kinetic reactions of CLA-DPPH(•) showed that all tested CLAs have exerted radical scavenging activities in a dose-dependent manner and observed to immediately react and quench DPPH radicals at all tested levels and no lag phase was noticed in CLA-DPPH(•) reactions. The median inhibitory concentration (IC₅₀) value for cis-9, trans-11 CLA was observed to be more effective than other tested CLA. Total antioxidant capacity (TAC) of all tested CLAs were less effective radical scavengers as compared to vitamin E and butylated hydroxytoluene, although all tested CLAs were quenched a high amount (P < 0.05) of DPPH free radicals.

DISCUSSION AND CONCLUSION

All tested CLAs have the ability to directly react and quench DPPH free radicals in ethanol. Furthermore, trans-10, cis-12 CLA has greater maximal efficacy than other tested CLAs as free radical scavenger, while cis-9, trans-11 CLA is the most potent isomer to directly react and quench free radicals at low concentrations in the system, suggesting that the free radical scavenging activity of CLA isomers may contribute to their diverse biological activities.

Effects of bezafibrate on lipid and glucose metabolism in dyslipidemic patients with diabetes: the J-BENEFIT study

BACKGROUND

The hypoglycemic effect of bezafibrate is well established, but administration to a large population of patients with diabetes has not been reported. We investigated glycemic control, relationship between lipid metabolism and HbA1c, and safety in diabetic patients treated with bezafibrate.

METHODS

A prospective, observational analysis was conducted on 6,407 dyslipidemic patients suffering from diabetes or hyperglycemia who had not received bezafibrate previously. Subanalyses were performed on the concomitant use of diabetes drugs, diabetes duration, and baseline HbA1c levels.

RESULTS

Bezafibrate significantly decreased HbA1c irrespective of concomitant use of other diabetes drugs in a baseline-HbA1c-dependent manner, with patients with a shorter diabetes duration showing a greater decrease in HbA1c than those with longer-term disease. The rate of change in triglyceride levels was significantly associated with that in HbA1c. Adverse drug reactions occurred in 306 patients (5.1%), of which reactions in 289 were not severe (94.4%).

CONCLUSIONS

Bezafibrate significantly improved HbA1c in patients with diabetes given individualized treatment. Bezafibrate may offer clinicians an improved modality for the amelioration of disease course and improvement of outcome in these patients.

Obesity: the preventive role of the pomegranate (Punica granatum)

Obesity represents a rapidly growing threat to the health of populations in an increasing number of countries. Diet intervention has been proposed as one of the strategies for weight loss and weight maintenance. Traditionally, the pomegranate, including its roots, tree bark, fruit juice, leaves, and flowers, has been used to treat some conditions such as diarrhea, hemorrhage, acidosis, and microbial infections. Pomegranate extracts have been found to have strong anti-inflammatory, antioxidant, and even antitumor properties in vivo and in vitro. More recently, positive effects on fat reduction have been shown using the pomegranate and its extracts. Many of the beneficial effects are related to the presence of anthocyanins, tannins, and very high levels of antioxidants, including polyphenols and flavonoids. Many studies have explored the effects of the pomegranate in obesity, and various mechanisms have been proposed as to how these different extracts help in fat reduction. This article provides an overview of the work done addressing the potential benefits of the pomegranate on obesity and assesses the efficacy of intervention by means of the pomegranate and its extracts. Human studies in this field are still limited and need more attention that would help in understanding the preventive and protective roles pomegranate extracts have on obesity.

GW0742, a high-affinity PPAR-δ agonist, mediates protection in an organotypic model of spinal cord damage

STUDY DESIGN

Experimental study of spinal cord injury (SCI) using an organotypic slice culture.

OBJECTIVE

To clarify the protective mechanism of PPAR-δ agonist GW0742 in the injured spinal cord using an in vitro model.

SUMMARY OF BACKGROUND DATA

In vivo data suggest that ligands of the δ isoform have activity in a number of disease models that are partly driven by the inflammatory response. Moreover, reports from in vivo studies using models of ischemia reperfusion and Parkinson disease also have shown neuroprotection conferred by PPAR-δ. The biological role and function of PPAR-δ remains relatively unclear.

METHODS

Spinal cord from 6-week-old mice was cut into transverse slices of 400-μm thickness to generate the organotypic slice cultures. The slices were injured using a weight dropped onto the center of the slice. PPAR-δ agonist was applied at 10 μM at 1 hour before injury.

RESULTS

Our study shows that GW0742 incubation (10 μM) at 1 hour before transverse lesion significantly reduced (1) p38 mitogen-activated protein kinase (MAPK), (2) c-Jun N-terminal kinase (JNK/SAP kinase), (3) NF-κB activation, (4) loss of neurotrophic factors (BDNF, GDNF), (5) COX-2 expression, and (6) cell death.

CONCLUSION

GW0742 reduces the cellular and molecular changes occurring in SCI by targeting different downstream pathways modulating PPAR-δ receptors.

Changes of peroxisome proliferator-activated receptor-γ on crushed rat sciatic nerves and differentiated primary Schwann cells

Peroxisome proliferator-activated receptor-γ (PPAR-γ) has been found to play an essential role in cell proliferation, but whether it was involved in Schwann cells differentiation has never been studied. We have found in sciatic nerve injury that expression of PPAR-γ decreases mainly in Schwann cells, and it was also increased in differentiated Schwann cells. Further, activated PPAR-γ by the endogenous ligand 15 d-PGJ(2) increased expressions of PPAR-γ level and Schwann cell differentiation, and this effect may be protected by its antagonist GDW9662. These results indicate that PPAR-γ could promote Schwann cell differentiation, which plays an important role in peripheral nerve injury and regeneration.

Farnesol, an isoprenoid, improves metabolic abnormalities in mice via both PPARα-dependent and -independent pathways

Peroxisome proliferator-activated receptors (PPARs) control energy homeostasis. In this study, we showed that farnesol, a naturally occurring ligand of PPARs, could ameliorate metabolic diseases. Obese KK-Ay mice fed a high-fat diet (HFD) containing 0.5% farnesol showed significantly decreased serum glucose level, glucosuria incidence, and hepatic triglyceride contents. Farnesol-containing HFD upregulated the mRNA expressions of PPARα target genes involved in fatty acid oxidation in the liver. On the other hand, farnesol was not effective in upregulating the mRNA expressions of PPARγ target genes in white adipose tissues. Experiments using PPARα-deficient [(-/-)] mice revealed that the upregulation of fatty acid oxidation-related genes required PPARα function, but the suppression of hepatic triglyceride accumulation was partially PPARα-dependent. In hepatocytes isolated from the wild-type and PPARα (-/-) mice, farnesol suppressed triglyceride synthesis. In luciferase assay, farnesol activated both PPARα and the farnesoid X receptor (FXR) at similar concentrations. Moreover, farnesol increased the mRNA expression level of a small heterodimer partner known as one of the FXR target genes and decreased those of sterol regulatory element-binding protein-1c and fatty acid synthase in both the wild-type and PPARα (-/-) hepatocytes. These findings suggest that farnesol could improve metabolic abnormalities in mice via both PPARα-dependent and -independent pathways and that the activation of FXR by farnesol might contribute partially to the PPARα-independent hepatic triglyceride content-lowering effect. To our knowledge, this is the first study on the effect of the dual activators of PPARα and FXR on obesity-induced metabolic disorders.

cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15 CLNA mixture activates PPARα in HEK293 and reduces triacylglycerols in 3T3-L1 cells

Scientific research is constantly working to find new molecules that are effective in preventing excessive accumulation of body fat. The aim of the present work was to assess the potential agonism on PPARα and PPARγ of a conjugated linolenic acid (CLNA) isomer mixture, consisting of two CLNA isomers (cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15). Secondly, we aimed to analyze the effects of this mixture on triacylglycerol accumulation in 3T3-L1 mature adipocytes. Luciferase transactivation assay was used to analyze whether the CLNA mixture activated PPARs. The expression of several enzymes and transcriptional factors involved in the main metabolic pathways that control triacylglycerol accumulation in adipocytes was assessed by real time RT-PCR in 3T3-L1 adipocytes treated for 20 h with the CLNA mixture. The mixture activated PPRE in cells with PPARα receptor over-expression, but not those with PPARγ over-expression. Decreased triacylglycerol was found in treated adipocytes. The lowest dose (10 μM) increased HSL expression and the highest dose (100 μM) increased ATGL gene expression. The other genes analyzed remained unchanged. The hypothesis of an anti-obesity action of the analyzed CLNA mixture, based on increased lipid mobilization in adipose tissue, can be proposed.

Dietary conjugated linoleic Acid and hepatic steatosis: species-specific effects on liver and adipose lipid metabolism and gene expression

Objective. To summarize the recent studies on effect of conjugated linoleic acid (CLA) on hepatic steatosis and hepatic and adipose lipid metabolism highlighting the potential regulatory mechanisms. Methods. Sixty-four published experiments were summarized in which trans-10, cis-12 CLA was fed either alone or in combination with other CLA isomers to mice, rats, hamsters, and humans were compared. Summary and Conclusions. Dietary trans-10, cis-12 CLA induces a severe hepatic steatosis in mice with a more muted response in other species. Regardless of species, when hepatic steatosis was present, a concurrent decrease in body adiposity was observed, suggesting that hepatic lipid accumulation is a result of uptake of mobilized fatty acids (FA) from adipose tissue and the liver's inability to sufficiently increase FA oxidation and export of synthesized triglycerides. The potential role of liver FA composition, insulin secretion and sensitivity, adipokine, and inflammatory responses are discussed as potential mechanisms behind CLA-induced hepatic steatosis.

Effects of ruminant trans fatty acids on cardiovascular disease and cancer: a comprehensive review of epidemiological, clinical, and mechanistic studies

There are 2 predominant sources of dietary trans fatty acids (TFA) in the food supply, those formed during the industrial partial hydrogenation of vegetable oils (iTFA) and those formed by biohydrogenation in ruminants (rTFA), including vaccenic acid (VA) and the naturally occurring isomer of conjugated linoleic acid, cis-9, trans-11 CLA (c9,t11-CLA). The objective of this review is to evaluate the evidence base from epidemiological and clinical studies to determine whether intake of rTFA isomers, specifically VA and c9,t11-CLA, differentially affects risk of cardiovascular disease (CVD) and cancer compared with iTFA. In addition, animal and cell culture studies are reviewed to explore potential pro- and antiatherogenic mechanisms of VA and c9,t11-CLA. Some epidemiological studies suggest that a positive association with coronary heart disease risk exists between only iTFA isomers and not rTFA isomers. Small clinical studies have been conducted to establish cause-and-effect relationships between these different sources of TFA and biomarkers or risk factors of CVD with inconclusive results. The lack of detection of treatment effects reported in some studies may be due to insufficient statistical power. Many studies have used doses of rTFA that are not realistically attainable via diet; thus, further clinical studies are warranted. Associations between iTFA intake and cancer have been inconsistent, and associations between rTFA intake and cancer have not been well studied. Clinical studies have not been conducted investigating the cause-and-effect relationship between iTFA and rTFA intake and risk for cancers. Further research is needed to determine the health effects of VA and c9,t11-CLA in humans.

Effect of a rumen-protected conjugated linoleic acid mixture on hepatic lipid metabolism in heifers

This study was performed to assess the effects of rumen-protected conjugated linoleic acid (CLA) on hepatic lipid metabolism in heifers. In particular, it was of interest whether feeding CLA causes development of fatty liver as observed recently in mice. Thirty-six growing heifers with an initial body weight of 185 kg were allotted to three treatment groups and fed daily 250 g of different rumen-protected fats for 16 weeks: The control group received 250 g of a CLA-free control fat, the CLA100 group received 100 g of a CLA fat containing 2.4% of cis-9, trans-11 CLA and 2.1% of trans-10, cis-12 CLA and 150 g control fat and the CLA250 group received 250 g of the CLA fat. CLA supplementation had no effect on animal performance parameters, liver weight and hepatic triglyceride concentration. Moreover, mRNA expression of hepatic genes involved in lipogenesis, β-oxidation and fatty acid transport was not influenced by dietary CLA. The fatty acid composition of hepatic total lipids, with particular consideration of ratios of fatty acids indicative of Δ9-, Δ6- and Δ5-desaturation, was also less influenced by dietary CLA. In conclusion, the study shows that dietary rumen-protected CLA has less effect on hepatic lipid metabolism in young heifers and does not induce the development of a fatty liver such as in mice.

Pomegranate seed oil, a rich source of punicic acid, prevents diet-induced obesity and insulin resistance in mice

BACKGROUND

Pomegranate seed oil has been shown to protect against diet induced obesity and insulin resistance.

OBJECTIVE

To characterize the metabolic effects of punicic acid on high fat diet induced obesity and insulin resistance.

DESIGN

High-fat diet or high-fat diet with 1% Pomegranate seed oil (PUA) was fed for 12 weeks to induce obesity and insulin resistance. We assessed body weight and composition (pSABRE DEXA-scan), energy expenditure (Columbus Instruments) and insulin sensitivity at the end of the 12 weeks.

RESULTS

PSO intake resulted in a lower body weight, 30.5±2.9 vs 33.8±3.2 g PSO vs HFD respectively, p=0.02, without affecting food intake or energy expenditure. The lower body weight was fully explained by a decreased body fat mass, 3.3±2.3 vs 6.7±2.7 g for PSO and HFD fed mice, respectively, p=0.02. Insulin clamps showed that PSO did not affect liver insulin sensitivity but clearly improved peripheral insulin sensitivity, 164±52% vs 92±24% for PSO and HFD fed mice respectively, p=0.01.

CONCLUSIONS

We conclude that dietary PSO ameliorates high-fat diet induced obesity and insulin resistance in mice, independent of changes in food intake or energy expenditure.

Monocarboxylate transporter 1 and CD147 are up-regulated by natural and synthetic peroxisome proliferator-activated receptor alpha agonists in livers of rodents and pigs

Monocarboxylate transporter (MCT)-1 mediates the transport of ketone bodies and other monocarboxylic acids across the plasma membrane. MCT1 is up-regulated by peroxisome proliferator-activated receptor (PPAR)-alpha, a transcription factor that mediates the adaptive response to fasting by up-regulation of genes involved in fatty acid oxidation and ketogenesis. Here, we show for the first time that MCT1 is up-regulated by dietary natural PPAR-alpha agonists. Both, an oxidized fat and conjugated linoleic acids increased MCT1 mRNA concentration in the liver of rats. Also, in the liver of pigs as non-proliferating species MCT1 was up-regulated upon PPAR-alpha activation by clofibrate, oxidized fat and fasting. Concomitant with up-regulation of MCT1, mRNA level of CD147 was increased in livers of rats and pigs. CD147 is a plasma membrane glycoprotein that is required for translocation and transport activity of MCT1. CD147 mRNA increase upon PPAR-alpha activation could not be observed in mice lacking PPAR-alpha, which also fail in up-regulation of MCT1 indicating a co-regulation of MCT1 and CD147. Analysis of the 5'-flanking region of mouse MCT1 gene by reporter gene assay revealed that promoter activity of mouse MCT1 was not induced by PPAR-alpha, indicating that the 5'-flanking region is not involved in MCT1 regulation by PPAR-alpha.

Role of PPAR-gamma in inflammation. Prospects for therapeutic intervention by food components

Peroxisome proliferator activated receptor gamma (PPARγ) is a ligand-dependent transcription factor and a member of the nuclear receptor superfamily. Acting as sensors of hormones, vitamins, endogenous metabolites and xenobiotic compounds, the nuclear receptors control the expression of a very large number of genes. PPARγ has been known for some time to regulate adipocyte differentiation, fatty acid storage and glucose metabolism, and is a target of anti-diabetic drugs. More recently, PPARγ has been recognized as playing a fundamentally important role in the immune response through its ability to inhibit the expression of inflammatory cytokines and to direct the differentiation of immune cells towards anti-inflammatory phenotypes. A feature of PPARγ is the structural diversity of its ligands, which encompass endogenous metabolites, dietary compounds and synthetic drugs. The high and increasing incidence of inflammatory and allergic disease, coupled with encouraging results from recent clinical trials, suggest that natural PPARγ agonists found in foods may be beneficial to human health by acting as anti-inflammatory molecules. PPARγ is therefore not only a target of the pharmaceutical industry, but also of great potential interest to the food industry, since it is activated by several natural dietary constituents. The prospects for dietary intervention in inflammatory disease have improved somewhat over the last few years, and are reviewed here.

Chronic expression of PPAR-delta by oligodendrocyte lineage cells in the injured rat spinal cord

The transcription factor peroxisome proliferator-activated receptor (PPAR)-delta promotes oligodendrocyte differentiation and myelin formation in vitro and is prevalent throughout the brain and spinal cord. Its expression after injury, however, has not been examined. Thus, we used a spinal contusion model to examine the spatiotemporal expression of PPAR-delta in naïve and injured spinal cords from adult rats. As previously reported, PPAR-delta was expressed by neurons and oligodendrocytes in uninjured spinal cords; PPAR-delta was also detected in NG2 cells (potential oligodendrocyte progenitors) within the white matter and gray matter. After spinal cord injury (SCI), PPAR-delta mRNA and protein were present early and increased over time. Overall PPAR-delta+ cell numbers declined at 1 day post injury (dpi), likely reflecting neuron loss, and then rose through 14 dpi. A large proportion of NG2 cells expressed PPAR-delta after SCI, especially along lesion borders. PPAR-delta+ NG2 cell numbers were significantly higher than naive by 7 dpi and remained elevated through at least 28 dpi. PPAR-delta+ oligodendrocyte numbers declined at 1 dpi and then increased over time such that >20% of oligodendrocytes expressed PPAR-delta after SCI compared with approximately 10% in uninjured tissue. The most prominent increase in PPAR-delta+ oligodendrocytes was along lesion borders where at least a portion of newly generated oligodendrocytes (bromodeoxyuridine+) were PPAR-delta+. Consistent with its role in cellular differentiation, the early rise in PPAR-delta+ NG2 cells followed by an increase in new PPAR-delta+ oligodendrocytes suggests that this transcription factor may be involved in the robust oligodendrogenesis detected previously along SCI lesion borders.

Metabolism and actions of conjugated linoleic acids on atherosclerosis-related events in vascular endothelial cells and smooth muscle cells

Conjugated linoleic acids (CLAs) are biologically highly active lipid compounds that have attracted great scientific interest due to their ability to cause either inhibition of atherosclerotic plaque development or even regression of pre-established atherosclerotic plaques in mice, hamsters and rabbits. The underlying mechanisms of action, however, are only poorly understood. Since cell culture experiments are appropriate to gain insight into the mechanisms of action of a compound, the present review summarizes data from cell culture studies about the metabolism and the actions of CLAs on atherosclerosis-related events in endothelial cells (ECs) and smooth muscle cells (SMCs), which are important cells contributing to atherosclerotic lesion development. Based on these studies, it can be concluded that CLAs exert several beneficial actions including inhibition of inflammatory and vasoactive mediator release from ECs and SMCs, which may help explain the anti-atherogenic effect of CLAs observed in vivo. The observation that significant levels of CLA metabolites, which have been reported to have significant biological activities, are well detectable in ECs and SMCs indicates that the anti-atherogenic effects observed with CLAs are presumably mediated not only by CLAs themselves but also by their metabolites.

Influence of conjugated linoleic acids on functional properties of vascular cells

Conjugated linoleic acids (CLA) are biologically highly active lipid compounds that inhibit the development of atherosclerotic plaques in experimental animals. The underlying mechanisms of action, however, are only poorly understood. Since cell-culture experiments are appropriate to provide a detailed view into the mechanisms of action of a compound, the present review summarises results fromin vitrostudies dealing with the effects of CLA isomers and CLA mixtures on functional properties of cells of the vascular wall, such as endothelial cells, smooth muscle cells and monocyte-derived macrophages, which are amongst the major cells contributing to atherosclerotic lesion development. Based on these studies, it can be concluded that CLA exert several beneficial actions in cells of the vascular wall through the activation of nuclear PPAR. These actions of CLA, which may, at least partially, explain the inhibition of atherogenesis by dietary CLA, include modulation of vasoactive mediator release from endothelial cells, inhibition of inflammatory and fibrotic processes in activated smooth muscle cells, abrogation of inflammatory responses in activated macrophages, and reduction of cholesterol accumulation in macrophage-derived foam cells.

Role of PPAR-gamma in inflammation. Prospects for therapeutic intervention by food components

Peroxisome proliferator activated receptor gamma (PPARgamma) is a ligand-dependent transcription factor and a member of the nuclear receptor superfamily. Acting as sensors of hormones, vitamins, endogenous metabolites and xenobiotic compounds, the nuclear receptors control the expression of a very large number of genes. PPARgamma has been known for some time to regulate adipocyte differentiation, fatty acid storage and glucose metabolism, and is a target of anti-diabetic drugs. More recently, PPARgamma has been recognized as playing a fundamentally important role in the immune response through its ability to inhibit the expression of inflammatory cytokines and to direct the differentiation of immune cells towards anti-inflammatory phenotypes. A feature of PPARgamma is the structural diversity of its ligands, which encompass endogenous metabolites, dietary compounds and synthetic drugs. The high and increasing incidence of inflammatory and allergic disease, coupled with encouraging results from recent clinical trials, suggest that natural PPARgamma agonists found in foods may be beneficial to human health by acting as anti-inflammatory molecules. PPARgamma is therefore not only a target of the pharmaceutical industry, but also of great potential interest to the food industry, since it is activated by several natural dietary constituents. The prospects for dietary intervention in inflammatory disease have improved somewhat over the last few years, and are reviewed here.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.

Biomolecular characterization of human glioblastoma cells in primary cultures: differentiating and antiangiogenic effects of natural and synthetic PPARgamma agonists

Gliomas are the most commonly diagnosed malignant brain primary tumors. Prognosis of patients with high-grade gliomas is poor and scarcely affected by radiotherapy and chemotherapy. Several studies have reported antiproliferative and/or differentiating activities of some lipophylic molecules on glioblastoma cells. Some of these activities in cell signaling are mediated by a class of transcriptional factors referred to as peroxisome proliferator-activated receptors (PPARs). PPARgamma has been identified in transformed neural cells of human origin and it has been demonstrated that PPARgamma agonists decrease cell proliferation, stimulate apoptosis and induce morphological changes and expression of markers typical of a more differentiated phenotype in glioblastoma and astrocytoma cell lines. These findings arise from studies mainly performed on long-term cultured transformed cell lines. Such experimental models do not exactly reproduce the in vivo environment since long-term culture often results in the accumulation of further molecular alterations in the cells. To be as close as possible to the in vivo condition, in the present work we investigated the effects of PPARgamma natural and synthetic ligands on the biomolecular features of primary cultures of human glioblastoma cells derived from surgical specimens. We provide evidence that PPARgamma agonists may interfere with glioblastoma growth and malignancy and might be taken in account as novel antitumoral drugs.

Role of peroxisome-proliferator-activated receptor beta/delta (PPARbeta/delta) in gastrointestinal tract function and disease

PPARbeta/delta (peroxisome-proliferator-activated receptor beta/delta) is one of three PPARs in the nuclear hormone receptor superfamily that are collectively involved in the control of lipid homoeostasis among other functions. PPARbeta/delta not only acts as a ligand-activated transcription factor, but also affects signal transduction by interacting with other transcription factors such as NF-kappaB (nuclear factor kappaB). Constitutive expression of PPARbeta/delta in the gastrointestinal tract is very high compared with other tissues and its potential physiological roles in this tissue include homoeostatic regulation of intestinal cell proliferation/differentiation and modulation of inflammation associated with inflammatory bowel disease and colon cancer. Analysis of mouse epithelial cells in the intestine and colon has clearly demonstrated that ligand activation of PPARbeta/delta induces terminal differentiation. The PPARbeta/delta target genes mediating this effect are currently unknown. Emerging evidence suggests that PPARbeta/delta can suppress inflammatory bowel disease through PPARbeta/delta-dependent and ligand-independent down-regulation of inflammatory signalling. However, the role of PPARbeta/delta in colon carcinogenesis remains controversial, as conflicting evidence suggests that ligand activation of PPARbeta/delta can either potentiate or attenuate this disease. In the present review, we summarize the role of PPARbeta/delta in gastrointestinal physiology and disease with an emphasis on findings in experimental models using both high-affinity ligands and null-mouse models.

Os efeitos do ácido linoléico conjugado no metabolismo animal: avanço das pesquisas e perspectivas para o futuro

Realizou-se uma revisão sistemática, sem restrição de data, sobre os efeitos fisiológicos do ácido linoléico conjugado sobre a regressão da carcinogênese, o estresse oxidativo, o metabolismo de lípides e glicose e a alteração da composição corporal. Objetivando estabelecer o aspecto histórico do avanço da pesquisa em ácido linoléico conjugado, consideraram-se artigos originais resultantes de trabalhos realizados com animais, com cultura de células e com humanos. Quanto às pesquisas sobre o efeito anticarcinogênico do ácido linoléico conjugado foram encontradas inúmeras evidências a esse respeito, especialmente na regressão dos tumores mamários e de cólon, induzida por ambos os isômeros os quais agem de maneiras distintas. Os pesquisadores se empenham em reinvestigar as propriedades antioxidantes do ácido linoléico conjugado. Embora tenham sido investigadas as propriedades antioxidantes, tem-se identificado efeito pró-oxidante, levando ao estresse oxidativo em humanos. Foram poucos os estudos que demonstraram efeito positivo significativo do ácido linoléico conjugado sobre o metabolismo dos lípides e da glicose e sobre a redução da gordura corporal, especialmente em humanos. Estudos sobre efeitos adversos foram também identificados. Há fortes indícios de que a ação deste ácido graxo conjugado sobre uma classe de fatores de transcrição - os receptores ativados por proliferadores de peroxissomo - e sobre a conseqüente modulação da expressão gênica, possa ser a explicação fundamental dos efeitos fisiológicos. Embora incipientes, os mais recentes estudos reforçam o conceito da nutrigenômica, ou seja, a modulação da expressão gênica induzida por compostos presentes na alimentação humana. O cenário atual estimula a comunidade científica a buscar um consenso sobre os efeitos do ácido linoléico conjugado em humanos, já que este está presente naturalmente em alguns alimentos, que, quando consumidos em quantidades adequadas e de forma freqüente, poderiam atuar como coadjuvantes na prevenção e no controle de inúmeras doenças crônicas.

Suppression of cardiac myocyte hypertrophy by conjugated linoleic acid: role of peroxisome proliferator-activated receptors alpha and gamma

Conjugated linoleic acid (CLA) refers to a naturally occurring mixture of positional and geometric isomers of linoleic acid. Evidence suggests that CLA is a dietary constituent and nutraceutical with anti-cancer, insulin-sensitizing, immunomodulatory, weight-partitioning, and cardioprotective properties. The aim of this study was to evaluate the effects of intervention with CLA on cardiac hypertrophy. In vitro, CLA prevented indicators of cardiomyocyte hypertrophy elicited by endothelin-1, including cell size augmentation, protein synthesis, and fetal gene activation. Similar anti-hypertrophic effects of CLA were observed in hypertrophy induced by angiotensin II, fibroblast growth factor, and mechanical strain. CLA may inhibit hypertrophy through activation of peroxisome proliferator-activated receptors (PPARs). CLA stimulated PPAR activity in cardiomyocytes, and the anti-hypertrophic effects of CLA were blocked by genetic and pharmacological inhibitors of PPAR isoforms alpha and gamma. CLA may disrupt hypertrophic signaling by stimulating diacylglycerol kinase zeta, which decreases availability of diacylglycerol and thereby inhibits the protein kinase Cepsilon pathway. In vivo, dietary CLA supplementation significantly reduced blood pressure and cardiac hypertrophy in spontaneously hypertensive heart failure rats. These data suggest that dietary supplementation with CLA may be a viable strategy to prevent pathological cardiac hypertrophy, a major risk factor for heart failure.

Effects of fish oil and conjugated linoleic acids on expression of target genes of PPAR alpha and sterol regulatory element-binding proteins in the liver of laying hens

In mammals, (n-3) PUFA and conjugated linoleic acids (CLA) act as activators of PPAR alpha and alter nuclear concentrations of sterol regulatory element-binding proteins (SREBP) in the liver, and thereby influence hepatic lipid catabolism and synthesis. In this study, we investigated the hypothesis that (n-3) PUFA and CLA exert similar effects in the liver of laying hens. Thirty hens (64 weeks old) were fed diets containing 30 g/kg of sunflower oil (control), fish oil (salmon oil) or CLA in TAG form (containing predominantly cis-9, trans-11 CLA and trans-10, cis-12 CLA) for 5 weeks. Hens fed fish oil had a higher expression of some PPAR alpha target genes and a lower nuclear concentration of SREBP-2 in the liver and lower concentrations of cholesterol and TAG in plasma than control hens. Nuclear concentration of SREBP-1 and its target genes involved in lipogenesis were not altered in hens fed fish oil. Hens fed CLA had increased concentrations of TAG and cholesterol in the liver. However, their mRNA levels of PPAR alpha target genes and nuclear concentrations of SREBP-1 and SREBP-2 as well as mRNA levels of their target genes in the liver were largely unchanged compared to control hens. The results of this study suggest that (n-3) PUFA cause a moderate activation of PPAR alpha and lower cholesterol synthesis but do not impair fatty acid synthesis in the liver of laying hens. CLA lead to an accumulation of TAG and cholesterol in the liver of hens by mechanisms to be elucidated in further studies.

Troglitazone but not conjugated linoleic acid reduces gene expression and activity of matrix-metalloproteinases-2 and -9 in PMA-differentiated THP-1 macrophages

Gene expression and activity of matrix-metalloproteinases (MMP)-2 and -9 in macrophages are reduced through peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent inhibition of NF-kappaB. Since conjugated linoleic acids (CLAs) are PPARgamma ligands and known to inhibit NF-kappaB via PPARgamma, we studied whether CLA isomers are capable of reducing gene expression and gelatinolytic activity of MMP-2 and -9 in PMA-differentiated THP-1 macrophages, which has not yet been investigated. Incubation of PMA-differentiated THP-1 cells with either c9t11-CLA, t10c12-CLA or linoleic acid (LA), as a reference fatty acid, resulted in a significant incorporation of the respective fatty acids into total cell lipids relative to control cells (P<.05). Treatment of PMA-differentiated THP-1 cells with 10 and 20 micromol/L troglitazone but not with 10 or 100 micromol/L c9t11-CLA, t10c12-CLA or LA reduced relative mRNA concentrations and activity of MMP-2 and MMP-9 compared to control cells (P<.05). DNA-binding activity of NF-kappaB and PPARgamma and mRNA expression of the NF-kappaB target gene cPLA2 were not influenced by treatment with CLA. In contrast, treatment of PMA-differentiated THP-1 cells with troglitazone significantly increased transactivation of PPARgamma and decreased DNA-binding activity of NF-kappaB and relative mRNA concentration of cPLA2 relative to control cells (P<.05). In conclusion, the present study revealed that CLA isomers, in contrast to troglitazone, did not reduce gene expression and activity of MMP-2 and -9 in PMA-differentiated THP-1 macrophages, which is probably explained by the observation that CLA isomers neither activated PPARgamma nor reduced DNA-binding activity of NF-kappaB. This suggests that CLA isomers are ineffective in MMP-associated extracellular matrix degradation which is thought to contribute to the progression and rupture of advanced atherosclerotic plaques.

Effect of dietary conjugated linoleic acid on body composition and energy balance in broiler chickens

The effect of dietary conjugated linoleic acid (CLA) on body composition and energy metabolism was investigated in broiler chickens. Male broiler chicks were assigned to receive either a control diet (1 % sunflower oil) or a diet containing CLA (1 % of a 1:1 mixture oftrans-10,cis-12 andcis-9,trans-11 isomers of octadecadienoic acid). The diets were fedad libitumfor 3 weeks and there were eight replicates per diet, each replicate including four chickens so that each treatment had thirty-two animals. The proportion of body fat was lower in the control group than in the CLA group. No significant differences as to the proportions of body water, ash and protein were observed. Feed and energy intake were significantly lower in CLA-fed birds. The percentage of ingested energy lost in excreta was higher after CLA feeding and heat expenditure as a percentage of ingested energy was lower in the CLA-fed group. The CLA-fed group showed a higher percentage of SFA and lower percentages of MUFA and PUFA in carcass fat. It is concluded that CLA stimulatedde novofatty acid synthesis and lowered desaturase activity.

Metabolism and short-term metabolic effects of conjugated linoleic acids in rat hepatocytes

Metabolic fate and short-term effects of a 1:1 mixture of cis-9,trans-11 and trans-10,cis-12-conjugated linoleic acids (CLA), compared to linoleic acid (LA), on lipid metabolism was investigated in rat liver. In isolated mitochondria CLA-CoA were poorer substrates than LA-CoA for carnitine palmitoyltransferase-I (CPT-I) activity. However, in digitonin-permeabilized hepatocytes, where interactions among different metabolic pathways can be simultaneously investigated, CLA induced a remarkable stimulatory effect on CPT-I activity. This stimulation can be ascribed to a reduced malonyl-CoA level in turn due to inhibition of acetyl-CoA carboxylase (ACC) activity. The ACC/malonyl-CoA/CPT-I system can therefore represent a coordinate control by which CLA may exert effects on the partitioning of fatty acids between esterification and oxidation. Moreover, the rate of oxidation to CO2 and ketone bodies was significantly higher from CLA; peroxisomes rather than mitochondria were responsible for this difference. Interestingly, peroxisomal acyl-CoA oxidase (AOX) activity strongly increased by CLA-CoA compared to LA-CoA. CLA, metabolized by hepatocytes at a higher rate than LA, were poorer substrates for cellular and VLDL-triacylglycerol (TAG) synthesis. Overall, our results suggest that increased fatty acid oxidation with consequent decreased fatty acid availability for TAG synthesis is a potential mechanism by which CLA reduce TAG level in rat liver.

The Effects of Simultaneous Administration of Dietary Conjugated Linoleic Acid and Telmisartan on Cardiovascular Risks in Rats

Dietary conjugated linoleic acid (CLA) and the antihypertensive drug, telmisartan, have both been shown to modify cardiovascular risks. The effects of a combination of these two agents have, however, not been investigated. This 20 week study sought to assess the therapeutic potential of a CLA/telmisartan co-administration in rats fed a high-fructose high-fat diet. Thirty-three male Sprague-Dawley rats were randomly assigned to five experimental groups, including control, losartan, telmisartan, CLA, and CLA + telmisartan-treated animals. Body weight, blood pressure, and blood levels of lipids, glucose, insulin, and inflammatory markers were measured. Co-administration of CLA and telmisartan resulted in significant (P < 0.05) reductions in body weight, visceral fat, serum total cholesterol, triglycerides, glucose, plasma insulin concentrations, and systolic blood pressure compared with those in the control group. Moreover, plasma levels of IL1-alpha and IFN-gamma were reduced and levels of IL1-beta, IL-4, IL-6, and IL-10, plus TNF-alpha were increased in the co-therapy group, compared with controls. In conclusion, this study suggests that a combination of CLA with telmisartan may modify several risk factors of cardiovascular disease commonly seen in metabolic syndrome. This combination of nutraceuticals and pharmaceuticals may be a safe and cost-effective strategy in a number of high-risk subjects. Future studies will further document clinical benefits of such combination therapy.

Involvement of PPAR gamma and E-cadherin/beta-catenin pathway in the antiproliferative effect of conjugated linoleic acid in MCF-7 cells

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid, which has been shown to exert beneficial effects against breast carcinogenesis. It has been reported that CLA could modulate cellular proliferation and differentiation through the activation of peroxisome proliferator-activated receptors (PPARs). Among different PPAR isotypes, PPAR gamma is involved in growth inhibition of transformed cells. Ligands of PPAR gamma are considered as potential anticancer drugs, so CLA was tested for its ability to induce PPAR gamma expression in MCF-7 breast cancer cells. The effects of CLA and of a specific synthetic PPAR gamma antagonist were evaluated on cell growth as well as on parameters responsible for cell growth regulation. We demonstrated here that CLA stimulated the expression of PPAR gamma to levels up to control and caused PPAR gamma translocation into the nucleus. Furthermore, the overexpression of PPAR gamma positively correlates with the inhibition of cell proliferation and with the modulation of ERK signaling induced by CLA; in all cases the administration of the antagonist reverted CLA effects. The PPAR-signaling pathway is connected with the beta-catenin/E-cadherin pathway, thus we evaluated CLA effects on the expression and cellular distribution of these proteins, which are involved in cell adhesion and responsible for invasive behavior. The treatment with CLA determined the up-regulation and the redistribution of beta-catenin and E-cadherin and the antagonist reverted only the effect on beta-catenin. These studies indicate that CLA regulates PPAR gamma expression by selectively acting as an agonist and may influence cell-cell adhesion and invasiveness of MCF-7 cells.