Dietary trans-10,cis-12 conjugated linoleic acid induces hyperinsulinemia and fatty liver in the mouse

Abstract

Conjugated linoleic acids (CLA) are a class of positional, geometric, conjugated dienoic isomers of linoleic acid (LA). Dietary CLA supplementation results in a dramatic decrease in body fat mass in mice, but also causes considerable liver steatosis. However, little is known of the molecular mechanisms leading to hepatomegaly. Although c9,t11- and t10,c12-CLA isomers are found in similar proportions in commercial preparations, the respective roles of these two molecules in liver enlargement has not been studied. We show here that mice fed a diet enriched in t10,c12-CLA (0.4% w/w) for 4 weeks developed lipoatrophy, hyperinsulinemia, and fatty liver, whereas diets enriched in c9,t11-CLA and LA had no significant effect. In the liver, dietary t10,c12-CLA triggered the ectopic production of peroxisome proliferator-activated receptor γ (PPARγ), adipocyte lipid-binding protein and fatty acid transporter mRNAs and induced expression of the sterol responsive element-binding protein-1a and fatty acid synthase genes. In vitro transactivation assays demonstrated that t10,c12- and c9,t11-CLA were equally efficient at activating PPARα, β/δ, and γ and inhibiting liver-X-receptor.Thus, the specific effect of t10,c12-CLA is unlikely to result from direct interaction with these nuclear receptors. Instead, t10,c12-CLA-induced hyperinsulinemia may trigger liver steatosis, by inducing both fatty acid uptake and lipogenesis. Conjugated linoleic acids (CLA) are a class of positional, geometric, conjugated dienoic isomers of linoleic acid (LA). Dietary CLA supplementation results in a dramatic decrease in body fat mass in mice, but also causes considerable liver steatosis. However, little is known of the molecular mechanisms leading to hepatomegaly. Although c9,t11- and t10,c12-CLA isomers are found in similar proportions in commercial preparations, the respective roles of these two molecules in liver enlargement has not been studied. We show here that mice fed a diet enriched in t10,c12-CLA (0.4% w/w) for 4 weeks developed lipoatrophy, hyperinsulinemia, and fatty liver, whereas diets enriched in c9,t11-CLA and LA had no significant effect. In the liver, dietary t10,c12-CLA triggered the ectopic production of peroxisome proliferator-activated receptor γ (PPARγ), adipocyte lipid-binding protein and fatty acid transporter mRNAs and induced expression of the sterol responsive element-binding protein-1a and fatty acid synthase genes. In vitro transactivation assays demonstrated that t10,c12- and c9,t11-CLA were equally efficient at activating PPARα, β/δ, and γ and inhibiting liver-X-receptor. Thus, the specific effect of t10,c12-CLA is unlikely to result from direct interaction with these nuclear receptors. Instead, t10,c12-CLA-induced hyperinsulinemia may trigger liver steatosis, by inducing both fatty acid uptake and lipogenesis. Conjugated linoleic acids (CLA) are a class of positional and geometric conjugated dienoic isomers of linoleic acid (LA) found in dairy products, in bovine and ovine meat, and in partially hydrogenated vegetable oils. Although c9,t11-CLA (also known as rumenic acid) is the main CLA isomer present in food, it is found in almost equal proportions with the t10,c12-CLA isomer in commercial CLA preparations. The effects of CLA have been thoroughly studied in various animal models (1Pariza M.W. Park Y. Cook M.E. The biologically active isomers of conjugated linoleic acid.Prog. Lipid Res. 2001; 40: 283-298Google Scholar, 2Kelly G.S. Conjugated linoleic acid: a review.Altern. Med. Rev. 2001; 6: 367-382Google Scholar). CLA have anticarcinogenic properties in both mice and rats (3Durgam V.R. Fernandes G. The growth inhibitory effect of conjugated linoleic acid on MCF-7 cells is related to estrogen response system.Cancer Lett. 1997; 116: 121-130Google Scholar), and delay the onset of atherosclerosis in rabbits (4Lee K.N. Kritchevsky D. Pariza M.W. Conjugated linoleic acid and atherosclerosis in rabbits.Atherosclerosis. 1994; 108: 19-25Google Scholar) and hamsters (5Nicolosi R.J. Rogers E.J. Kritchevsky D. Scimeca J.A. Huth P.J. Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atheroclerosis in hypercholesterolemic hamsters.Artery. 1997; 22: 266-277Google Scholar). CLA-enriched diets also cause rapid, massive changes in body composition, particularly in the mouse, in which a decrease in fat stores associated with an increase in lean body mass has been reported (6Park Y. Albright K.J. Liu W. Storkson J.M. Cook M.E. Pariza M.W. Effect of conjugated linoleic acid on body composition in mice.Lipids. 1997; 32: 853-858Google Scholar, 7West D.B. Delany J.P. Camet P.M. Blohm F. Truett A.A. Scimeca J. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse.Am. J. Physiol. 1998; 275: R667-R672Google Scholar). Much is now known about the physiological basis of the CLA-induced decrease in adipose tissue mass. CLA supplementation leads to an increase in energy expenditure (7West D.B. Delany J.P. Camet P.M. Blohm F. Truett A.A. Scimeca J. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse.Am. J. Physiol. 1998; 275: R667-R672Google Scholar), which may be secondary to a stimulation of sympathetic nervous activity (8Ohnuki K. Haramizu S. Oki K. Ishihara K. Fushiki T. A single oral administration of conjugated linoleic acid enhanced energy metabolism in mice.Lipids. 2001; 36: 583-587Google Scholar). CLA reduce lipid uptake and storage in 3T3-L1 adipocytes by inhibiting lipoprotein lipase (9Park Y. Albright K.J. Storkson J.M. Liu W. Cook M.E. Pariza M.W. Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid.Lipids. 1999; 34: 243-248Google Scholar, 10Lin Y. Schuurbiers E. Van der Veen S. De Deckere E.A. Conjugated linoleic acid isomers have differential effects on triglyceride secretion in Hep G2 cells.Biochim. Biophys. Acta. 2001; 1533: 38-46Google Scholar) and stearoyl-CoA desaturase-I (11Choi Y. Park Y. Pariza M.W. Ntambi J.M. Regulation of stearoyl-CoA desaturase activity by the trans-10,cis-12 isomer of conjugated linoleic acid in HepG2 cells.Biochem. Biophys. Res. 2001; 284: 689-693Google Scholar) activities. Finally, it has been suggested that the decrease in adipose tissue involves an apoptotic mechanism linked to an increase in tumor necrosis factor α production (12Tsuboyama-Kasaoka N. Takahashi M. Tanemura K. Kim H.J. Tange T. Okuyama H. Kasai M. Ikemoto S. Ezaki O. Conjugated linoleic acid supplementation reduces adipose tissue by apoptosis and develops lipodystrophy in mice.Diabetes. 2000; 49: 1534-1542Google Scholar). Recent studies with purified isomers have strongly suggested that CLA-induced fat loss is dependent on the t10,c12-CLA isomer in the mouse (13Park Y. Storkson J.M. Albright K.J. Liu W. Pariza M.W. Evidence that the trans-10,cis-12 isomer of conjugated linoleic acid induces body composition changes in mice.Lipids. 1999; 34: 235-241Google Scholar). Another consequence of dietary CLA supplementation in mice is massive liver enlargement (12Tsuboyama-Kasaoka N. Takahashi M. Tanemura K. Kim H.J. Tange T. Okuyama H. Kasai M. Ikemoto S. Ezaki O. Conjugated linoleic acid supplementation reduces adipose tissue by apoptosis and develops lipodystrophy in mice.Diabetes. 2000; 49: 1534-1542Google Scholar, 14DeLany J.P. Blohm F. Truett A.A. Scimeca J.A. West D.B. Conjugated linoleic acid rapidly reduces body fat content in mice without affecting energy intake.Am. J. Physiol. 1999; 276: R1172-R1179Google Scholar, 15DeLany J.P. West D.B. Changes in body composition with conjugated linoleic acid.J. Am. Coll. Nutr. 2000; 19: 487S-493SGoogle Scholar, 16West D.B. Blohm F.Y. Truett A.A. DeLany J.P. Conjugated linoleic acid persistently increases total energy expenditure in AKR/J mice without increasing uncoupling protein gene expression.J. Nutr. 2000; 130: 2471-2477Google Scholar). However, the cellular and molecular mechanisms involved in this process are unknown. It has been suggested that the effects of CLA on the liver may be partially controlled by peroxisome proliferator-activated receptor α (PPARα) (17Moya-Camarena S.Y. Vanden Heuvel J.P. Belury M.A. Conjugated linoleic acid activates peroxisome proliferator-activated receptor α and β subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats.Biochim. Biophys. Acta. 1999; 1436: 331-342Google Scholar), a nuclear receptor known to regulate lipid metabolism in this organ (18Schoonjans K. Peinado-Onsurbe J. Lefebvre A-M. Heyman R.A. Briggs M. Deeb S. Staels B. Auwerx J. PPARα and PPARγ activators direct a distinct tissue-specific transcriptional response via a PPRE in the lipoprotein lipase gene.EMBO J. 1996; 15: 5336-5348Google Scholar). Indeed, both c9,t11-CLA and t10,c12-CLA have been shown to activate PPARα in transfection assays (17Moya-Camarena S.Y. Vanden Heuvel J.P. Belury M.A. Conjugated linoleic acid activates peroxisome proliferator-activated receptor α and β subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats.Biochim. Biophys. Acta. 1999; 1436: 331-342Google Scholar). Consistent with this finding, an isomeric CLA mixture induced the expression of typical PPARα target genes encoding proteins involved in hepatic lipid transport (liver fatty acid-binding protein or L-FABP) and catabolism (acyl-CoA oxidase, and cytochrome P450 4A1) (19Belury M.A. Moya-Camarena S.Y. Liu K-L. Vanden Heuvel J.P. Dietary conjugated linoleic acid induces peroxisome-specific enzyme accumulation and ornithine decarboxylase activity in mouse liver.J. Nutr. Biochem. 1997; 8: 579-584Google Scholar). However, the role of PPARα in CLA-mediated steatosis remains to be clarified. Other transcription factors in addition to PPARα, such as liver-X-receptors (LXRs) and sterol responsive element-binding protein 1 (SREBP1), play a critical role in hepatic lipid metabolism by controlling de novo fatty acid synthesis (20Peet J. Janowski B.A. Mangelsdorf D.J. The LXRs: a new class of oxysterol receptors.Curr. Opin. Genet. Dev. 1998; 8: 571-575Google Scholar, 21Shimano H. Sterol regulatory element-binding protein-1 as a dominant transcription factor for gene regulation of lipogenic enzymes in the liver.Trends Cardiovas. Med. 2000; 10: 275-278Google Scholar). It was recently suggested that the balance within the cell between oxysterols and polyunsaturated fatty acids (PUFA), which interfere with LXR activation in vitro, is a crucial determinant of hepatic lipogenesis (22Yoshikawa T. Shimano H. Yahagi N. Ide T. Amemiya-Kudo M. Matsuzaka T. Nakakuki M. S. H. Y. Y. K. Takahashi H. J. T. S. N. fatty acids sterol regulatory element-binding protein activity by of liver receptor to LXR response Scholar). It has also been that is a of this was to the effects of dietary supplementation with purified CLA The effects of purified c9,t11-CLA and t10,c12-CLA were in mice fed an isomer for 4 We found that the t10,c12-CLA isomer was for CLA-induced and liver steatosis. A in the of hepatic gene lipid was in mice fed a diet in In vitro transactivation assays that this effect on gene expression was not by the direct activation of or Instead, it may have been triggered by the increase in induced by dietary for the and of were mice at the of the were in a controlled and from to The and body mass of mouse were at the effects on body composition of the two main CLA isomers found in commercial preparations, mice were fed for 4 weeks on a diet or linoleic acid or purified CLA isomers or t10,c12-CLA The diets were We are responsive to CLA supplementation (6Park Y. Albright K.J. Liu W. Storkson J.M. Cook M.E. Pariza M.W. Effect of conjugated linoleic acid on body composition in mice.Lipids. 1997; 32: 853-858Google Scholar). were by The mice were and liver and adipose tissue was rapidly in and at of of of of in a new was from liver and by the N. of by acid Biochem. Scholar). It was to in a and to a as H. of the fatty acid protein gene in mouse liver by Lett. Scholar). were from various the liver fatty acid-binding protein was from J. adipocyte lipid-binding protein and fatty acid transporter were from fatty acid synthase was from and was from The were with a A specific for was as a to that of were and was and was by transcription of of total in a total of and was with of transcription in of with and in a of in an to for it was to that the was not to from without from the of with no or were also by in an to that a single of the was and were to in the of for as was by the between the of the gene in the and the to are as of The and and for and for and for and for and for and for were in cells cells were in at a in with 4 and cells were with and in were with with 4 were with 4 of H. O. T. W. of and in and of the gene encoding liver protein in the liver and the J. 2001; Scholar) and with of for mouse PPARα S. of of the receptor by peroxisome Scholar), F. G. of a protein that transcriptional effects of fatty acids in Scholar), PPARγ B. Mangelsdorf D.J. K. expression and activation of a of peroxisome 1994; Scholar), or We 1 of the in which expression of the gene is by the as an of transfection was by the J. T. In A Scholar). were with or t10,c12-CLA with fatty in with were were and for and activities. to We the effects of LA and CLA isomers on transactivation by transfection assays with a encoding proteins the of the transcription factor to the of PPARα, or PPARγ and a of the from the and the as E. Lefebvre Peinado-Onsurbe J. J. Staels B. of liver gene expression and lipid by acid via Lipid Res. 1999; 40: Scholar). cells were by for at in without with the lipid of and of expression or of was as a for transfection were for with or with various of or t10,c12-CLA to was in the and of specific of PPARα, and and the of the the cells were with in and activity was with the The protein content of the was by the from cells were in with in at a of of which of the response and of a the of of as a We of the for of the were by for with in The was with with and various of or t10,c12-CLA to or the The cells were for which and the cells for a were and for were on the basis of to The total lipid content of was by Scholar). was by and were by and The results are as The of between was by CLA supplementation to a significant decrease in energy for and for t10,c12-CLA in effect has been reported in studies (9Park Y. Albright K.J. Storkson J.M. Liu W. Cook M.E. Pariza M.W. Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid.Lipids. 1999; 34: 243-248Google Scholar) and is not Indeed, a similar decrease was also found in mice fed a diet with LA The addition of LA and CLA as fatty acids as to in for these diets (7West D.B. Delany J.P. Camet P.M. Blohm F. Truett A.A. Scimeca J. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse.Am. J. Physiol. 1998; 275: R667-R672Google Scholar). A decrease in body mass in mice fed a diet in but no significant was found at the of the not In to the results for and the diet enriched in t10,c12-CLA in a dramatic decrease in the mass of The of the mRNAs encoding adipocyte lipid-binding protein also and fatty acid synthase two proteins known to be involved in fatty acid uptake and accumulation in the was also in mice fed this diet in mice the t10,c12-CLA diet triggered a massive enlargement of the liver which the typical of a fatty and accumulation of steatosis is induced by t10,c12-CLA mice were fed for 4 weeks on diets or linoleic acid or liver mass and hepatic lipid We the CLA-mediated effect on adipose tissue and liver lipid metabolism was to the direct activation of by of a and specific proteins the of the transcription factor to the of of the known and and a gene by of the response from the gene E. Lefebvre Peinado-Onsurbe J. J. Staels B. of liver gene expression and lipid by acid via Lipid Res. 1999; 40: Scholar). LA and the two CLA isomers were found to be PPARα whereas was to a and the effect on PPARγ activation was Consistent with the results by Moya-Camarena (17Moya-Camarena S.Y. Vanden Heuvel J.P. Belury M.A. Conjugated linoleic acid activates peroxisome proliferator-activated receptor α and β subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats.Biochim. Biophys. Acta. 1999; 1436: 331-342Google Scholar), c9,t11-CLA to be efficient t10,c12-CLA at activating Indeed, t10,c12-CLA was to the of PPARα activation with c9,t11-CLA Thus, the direct activation of by t10,c12-CLA for the of fatty liver by this However, CLA may typical PPARα target genes. We this by cells with a of the from a gene and expression The PPARα the increase in of transactivation of the were in the of c9,t11-CLA with t10,c12-CLA or LA In both and diets induced a significant increase in liver whereas the LA diet not The accumulation of CLA in the liver the of CLA active may for this of the effect of linoleic acid or t10,c12-CLA on the regulation of a typical PPARα target cells were with a in which the was from the and with encoding PPARα, or were as in the and with LA or purified the activity is as activity with to mice were fed for 4 weeks on diets linoleic acid or or fatty acid-binding protein were by Changes with to the were for are known to the lipogenic The molecular basis of this regulation was recently and involves between physiological LXR and for the LXR leading to the of by a crucial in lipogenesis (22Yoshikawa T. Shimano H. Yahagi N. Ide T. Amemiya-Kudo M. Matsuzaka T. Nakakuki M. S. H. Y. Y. K. Takahashi H. J. T. S. N. fatty acids sterol regulatory element-binding protein activity by of liver receptor to LXR response Scholar). We the effects of CLA on LXR activity by cells with a encoding a to the of and a in which expression of the reported gene was by a The of this was We a increase in activity the specific physiological LXR was and this was in with LA of gene transactivation by was in the both c9,t11-CLA and that the two CLA inhibitory effects on LXR activation similar to of LA of hepatic gene expression may be for liver steatosis. We this by the of expression of genes encoding transcription lipid-binding and enzymes known to play a significant role in lipid and diets had no significant effect on the of expression of the genes studied. supplementation with the t10,c12-CLA isomer PPARγ was by the of two typical PPARγ target encoding the fatty acid transporter and the known to be involved in uptake in A but significant increase in liver sterol responsive element-binding protein was also expression of the which a t10,c12-CLA Finally, encoding PPARα, and liver-X-receptors no in The hepatic developed by mice fed the diet liver associated with the of PPARγ and is similar to that found in J.A. Ikemoto S. Y. and in mice nuclear in adipose for Dev. 1998; Scholar), J. M. D. O. B. E. T. M. without a Dev. 1998; Scholar), and S. K. J. J. S. R.A. is of adipose 1997; Scholar) of the PPARγ M. proliferator-activated receptor gene expression in Effects of and regulation by and 1997; Scholar) and genes is by and an between plasma and has been found in these mouse We to these two is by both and adipose cells as a of fat the of fat stores by t10,c12-CLA supplementation was associated with a significant decrease in plasma which was not in mice fed the or A dramatic increase in plasma was in mice fed the these mice mice fed and or diets this hyperinsulinemia, plasma within the in these mice The effects of CLA supplementation in body fat mass have a of but the effects of CLA on the liver and balance have been is CLA-mediated hyperinsulinemia have been in animal studies G.S. Conjugated linoleic acid: a review.Altern. Med. Rev. 2001; 6: 367-382Google Scholar) and a an increase in has been reported in E.A. P.J. Conjugated linoleic acid supplementation in effects on and 2000; Scholar). The effects of CLA are dramatic in the mouse in which supplementation with a mixture of the c9,t11-CLA and t10,c12-CLA induces a loss of body fat and massive fatty liver by hyperinsulinemia (12Tsuboyama-Kasaoka N. Takahashi M. Tanemura K. Kim H.J. Tange T. Okuyama H. Kasai M. Ikemoto S. Ezaki O. Conjugated linoleic acid supplementation reduces adipose tissue by apoptosis and develops lipodystrophy in mice.Diabetes. 2000; 49: 1534-1542Google Scholar). the that the t10,c12-CLA isomer is for this which the found in J.A. Ikemoto S. Y. and in mice nuclear in adipose for Dev. 1998; Scholar), J. M. D. O. B. E. T. M. without a Dev. 1998; Scholar), and mice S. K. J. J. S. R.A. is of adipose 1997; Scholar). It also for changes in the of hepatic gene to fat accumulation in the Indeed, the and specific of genes at in the liver, such as encoding and was in mice fed the hepatic of the PPARγ gene has also been reported in and mice and in mice, that it is a specific of M. of peroxisome proliferator-activated receptor expression in the from models of and Scholar). and are cellular lipid-binding is to increase fatty acid uptake in the The increase in in t10,c12-CLA fed mice that the lipogenic activity of the liver is also induced by this CLA effect may be for by the of the which is known to be involved in regulation of the hepatic lipogenic H. of and fatty acids causes massive liver enlargement in mice 1996; Scholar). It was recently suggested that the CLA-mediated changes in body composition result from the direct activation of (17Moya-Camarena S.Y. Vanden Heuvel J.P. Belury M.A. Conjugated linoleic acid activates peroxisome proliferator-activated receptor α and β subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats.Biochim. Biophys. Acta. 1999; 1436: 331-342Google Scholar). The of of a in mice fed a diet enriched in this isomer also and activate PPARα and is not with this Indeed, the of typical PPARα and target such as H. O. T. W. of and in and of the gene encoding liver protein in the liver and the J. 2001; Scholar), by both t10,c12-CLA and c9,t11-CLA this activity from hepatic fat is with in Indeed, the activation of PPARα target genes is not in the liver of mice, the of PPARα does not the of body fat mass and liver enlargement J.M. Park Y. Pariza M.W. of conjugated linoleic acid on body composition and target gene expression in peroxisome proliferator-activated receptor Biophys. Acta. 2001; 1533: Scholar). LXR is transcription factor known to be involved in regulation of the enzymes of lipogenesis. activation assays have demonstrated that t10,c12-CLA-induced fat storage in the liver be for by a specific effect of this CLA both the c9,t11-CLA and t10,c12-CLA isomers in a similar to (22Yoshikawa T. Shimano H. Yahagi N. Ide T. Amemiya-Kudo M. Matsuzaka T. Nakakuki M. S. H. Y. Y. K. Takahashi H. J. T. S. N. fatty acids sterol regulatory element-binding protein activity by of liver receptor to LXR response Scholar). Thus, that liver steatosis is not dependent on the specific of PPARα, and or Thus, the of leading to t10,c12-CLA-induced in the liver remains but is of strongly that the liver steatosis in mice is secondary to hyperinsulinemia, which causes of uptake and synthesis fatty liver was not in mice, which and In these of expression of the PPARγ and genes were and similar to in mice fed the in mice and in and mice, fat in the liver is and are by (12Tsuboyama-Kasaoka N. Takahashi M. Tanemura K. Kim H.J. Tange T. Okuyama H. Kasai M. Ikemoto S. Ezaki O. Conjugated linoleic acid supplementation reduces adipose tissue by apoptosis and develops lipodystrophy in mice.Diabetes. 2000; 49: 1534-1542Google Scholar, Ikemoto S. and in mice with 1999; Scholar, O. B. and in 2000; Scholar). hyperinsulinemia is associated with the of PPARγ gene expression in the liver and with liver steatosis in mouse models M. of peroxisome proliferator-activated receptor expression in the from models of and Scholar). is known to PPARγ gene expression in adipocytes M. proliferator-activated receptor gene expression in Effects of and regulation by and 1997; Scholar) and to induce gene expression in the liver J.A. as factors in fatty acid and Scholar, H. Sterol regulatory element-binding proteins transcriptional of lipid Lipid Res. 2001; 40: Scholar). Finally, and the of strongly that the of mice to The cause of the dramatic hyperinsulinemia triggered by the diet remains to be are to CLA supplementation secretion by CLA have been found to body composition in animal models mice, and However, it is the effects of t10,c12-CLA isomer found in the mouse be to Indeed, the response to CLA to be with mice S.Y. Belury M.A. in the metabolism and regulation of gene expression by conjugated linoleic Rev. 1999; Scholar). within a single between may be of fat accumulation in the liver to be in and AKR/J mice in mice and In a Pariza these in CLA to body fat which may be in mice in Indeed, CLA-mediated fat loss to be dependent on fat the of CLA on adipose tissue results in the of fatty acid uptake by the with no in the activity of the cell (1Pariza M.W. Park Y. Cook M.E. The biologically active isomers of conjugated linoleic acid.Prog. Lipid Res. 2001; 40: 283-298Google Scholar). the of a effect of CLA on body fat mass in may be to of fat during the of the (1Pariza M.W. Park Y. Cook M.E. The biologically active isomers of conjugated linoleic acid.Prog. Lipid Res. 2001; 40: 283-298Google Scholar). In studies have been and the results are not no significant in body fat mass and energy expenditure was found in Van B. Conjugated linoleic acid supplementation in effects on body composition and energy 2000; Scholar) to CLA supplementation for a CLA or for was found to be associated with a significant decrease in body fat mass in and H. J.A. H. E. J. O. Conjugated linoleic acid reduces body fat mass in and Nutr. 2000; 130: Scholar). the effects of t10,c12-CLA on the liver demonstrated in the mouse the of for be as to the of CLA supplementation with a commercial mixture as a of was by from and the to We and for adipocyte lipid-binding protein conjugated linoleic fatty acid synthase fatty acid transporter linoleic acid liver fatty acid-binding protein peroxisome proliferator-activated receptor sterol responsive element-binding protein adipose tissue