Abstract
Short-term effects of physiological concentrations of conjugated linoleic acid (CLA) on membrane integrity, metabolic function, cellular lipid composition, lipid peroxidation, and antioxidant enzymes were examined using rat hepatocyte suspension cultures. Incubation with CLA (5–20 ppm) for 3 h decreased the ability of hepatocyte plasma membranes to exclude trypan blue by approximately 25%, and caused leakage of cytosolic lactate dehydrogenase (LDH) into the medium. The significant decrease (P<0.02) in hepatocyte viability as measured by LDH leakage during cell incubation with 10 and 20 ppm CLA was not associated with significant changes in cellular ATP content. Protein synthesis in hepatocytes was elevated (P<0.05) in the presence of 5 and 10 ppm CLA, but at a higher concentration (20 ppm), protein synthesis was similar to that of control cells. Gluconeogenesis was maintained in cells incubated with lower concentrations of CLA (5 and 10 ppm) but was decreased (P<0.02) at the higher concentration. Incubation with 20 ppm CLA for 3 h did not affect the specific activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme of cholesterol synthesis. Both cis-9,trans-11/trans-9,cis-11, and cis-10,trans-12/trans-10,cis-12 isomers of CLA were incorporated to a similar level into hepatocytes. Levels ranged from 3.9 to 4.1%, respectively, of total fatty acids in neutral lipids, and from 0.7 to 0.8%, respectively, of total fatty acids in phospholipids. Cellular lipid peroxidation remained unchanged in the presence of CLA (5–20 ppm), despite significant inhibition (P<0.05) of superoxide dismutase. Catalase activity was maintained near control levels in the presence of 5 and 10 ppm CLA but was significantly decreased in the presence of 20 ppm CLA. Glutathione peroxidase activity was significantly decreased in the presence of 10 ppm CLA. The apparent sensitivity of the antioxidant enzyme defense system of liver cells to CLA, coupled with the lack of effect of CLA on lipid peroxidation in cells, suggests that cytotoxic effects of CLA as described by LDH leakage and decreased gluconeogenesis were not mediated by a prooxidant action in hepatocytes.
Similar content being viewed by others
Abbreviations
- CLA:
-
conjugated linoleic acid
- FAME:
-
fatty acid methyl ester
- GLC:
-
gas-liquid chromatography
- GPx:
-
gluthathione peroxidase
- HBSS:
-
Hanks' balanced salt solution
- HMGCoA reductase:
-
3-hydroxy-3-methylglutaryl coenzyme A reductase
- LDH:
-
lactate dehydrogenase
- PBS:
-
phosphate-buffered saline
- PUFA:
-
polyunsaturated fatty acids
- SOD:
-
superoxide dismutase
- TBARS:
-
thiobarbituric acid-reactive substances
References
Chin, S.F., Liu, W., Storkson, J.M., Ha, Y.L., and Pariza, M.W. (1992) Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, A Newly Recognized Class of Anticarcinogens, J. Food Compos. Anal. 5, 185–197.
Sehat, N., Yurawecz, M.P., Roach, J.A.G., Mossoba, M.M., Kramer, J.K.G., and Ku, Y. (1998) Silver-Ion-High-Performance Liquid Chromatographic Separation and Identification of Conjugated Linoleic Acid Isomers, Lipids 33, 217–221.
Kramer, J.K., Sehat, N., Dugan, M.E., Mossoba, M.M., Yurawecz, M.P., Roach, J.A., Eulitz, K., Aalhus, J.L., Schaefer, A.L., and Ku, Y. (1998) Distributions of Conjugated Linoleic Acid (CLA) Isomers in Tissue Lipid Classes of Pigs Fed a Commerical CLA Mixture Determined by Gas Chromatography and Silver Ion-High-Performance Liquid Chromatography, Lipids 33, 549–558.
Pariza, M.W., and Hargraves, W.A. (1985) A Beef-Derived Mutagenesis Modulator Inhibits Initiation of Mouse Epidermal Tumours by 7,12-Dimethylbenz[a]anthracene, Carcinogenesis, 6, 591–593.
Ip, C., Chin, S.F., Scimeca, J.A., and Pariza, M.W. (1991) Mammary Cancer Prevention by Conjugated Dienoic Derivative of Linoleic Acid, Cancer Res. 51, 6118–6124.
Liew, C., Schut, H.A.J., Chin, S.F., Pariza, M.W., and Dashwood, R.H. (1995) Protection of Conjugated Linoleic Acids Against 2-Amino-3-methylimidazo[4,5-f]Quinoline-Induced Colon Carcinogenesis in the F344 Rat—A Study of Inhibitory Mechanisms, Carcinogenesis 16, 3037–3043.
Ha, Y.L., Storkson, J., and Pariza, M.W. (1990) Inhibition of Benzo(a)pyrene-Induced Mouse Forestomach Neoplasia by Conjugated Dienoic Derivatives of Linoleic Acid, Cancer Res. 50, 1097–1101.
Ip, C., Jiang, C., Thompson, H.J., and Scimeca, J.A. (1997) Retention of Conjugated Linoleic Acid in the Mammary Gland Is Associated with Tumour Inhibition During the Post-Initiation Phase of Carcinogenesis, Carcinogenesis 18, 755–759.
Ip, C., Scimeca, J.A., and Thompson, H.J. (1995) Effect of Timing and Duration of Dietary Conjugated Linoleic Acid on Mammary Cancer Prevention, Nutr. Cancer 24, 241–247.
Scimeca, J.A. (1998) Toxicological Evaluation of Dietary Conjugated Linoleic Acid in Male Fischer 344 Rats, Food Chem. Toxicol. 36, 391–395.
Vickers, A.E. (1997) Experimental in vitro Models to Evaluate Hepatotoxicity, in In vitro Methods in Pharmaceutical Research, J.V. Castell (ed.), pp. 104–129, Academic Press Ltd., San Diego.
Belury, M.A., and Kempa-Steczko, A. (1997) Conjugated Linoleic Acid Modulates Hepatic Lipid Composition in Mice, Lipids 32, 199–204.
Belury, M.A., Moya-Camerena, S.Y., Liu, K.L., and Vanden Heuvel, J.P. (1997) Dietary Conjugated Linoleic Acid Induces Peroxisome-Specific Enzyme Accumulation and Ornithine Decarboxylase Activity in Mouse Liver, J. Nutr. Biochem. 8, 579–584.
Bayly, A.C., Roberts, R.A., and Dive, C. (1994) Suppression of Liver Cell Apoptosis in vitro by the Non-genotoxic Hepatocarcinogen and Peroxisome Proliferator, Nafenopin, J. Cell Biol. 125, 197–203.
Hayes, J.D., Ellis, E.M., Neal, G.E., Harrison, D.J., and Manson, M.M. (1998) Cellular Response to Cancer Chemopreventive Agents: Contribution of the Antioxidant Responsive Element to the Adaptive Response to Oxidative and Chemical Stress, Biochem. Soc. Symp. 64, 141–168.
Blaauboer, B.J., Boobis, A.R., Castell, J.V., Coecke, S., Groothuis, G.M.M., Guillouzo, A., Hall, T.J., Hawksworth, G.M., Lorenzon, G., Mittenburger, H.G., Rogiers, V., Skett, P., Villa, P., and Wiebal, F.J. (1994) The Practical Applicability of Hepatocyte Cultures in Routine Testing, ATLA 22, 231–241.
Berry, M.N., Edwards, A.M., and Barritt, G.J. (1991) Isolated Hepatocytes: Preparation, Properties and Applications, pp. 92–94, Elsevier, Amsterdam.
Folch, J., Lees, M., and Sloane-Stanley, G.H. (1957) A Simple Method for the Isolation and Purification of Total Lipid from Animal Tissues, J. Biol. Chem. 226, 497–509.
Stanton, C., Lawless, F., Kjellmer, G., Harrington, D., Devery, R., Connolly, J.F., and Murphy, J. (1997) Dietary Influences on Bovine Milk cis-9,trans-11-Conjugated Linoleic Acid Content, J. Food Sci. 62, 1083–1086.
Lawless, F., Murphy, J.J., Harrington, D., Devery, R., and Stanton, C. (1998) Elevation of Conjugated cis-9,trans-11-Octadecadienoic Acid in Bovine Milk Because of Dietary Supplementation, J. Dairy Sci. 81, 3259–3267.
Pieczonka, C.M., and Dehn, P.F. (1993) An Automated Endpoint Microassay for Adenosine-5′-triphosphate Using a Microplate Reader, J. Tissue Cult. Methods 15, 210–215.
Aebi, H. (1984) Catalase in vitro, Methods Enzymol. 105, 121–126.
Esterbauer, H., and Cheeseman, K.H. (1990) Determination of Aldehydic Lipid Peroxidation Products: Malonaldehyde and 4-Hydroxynonenal, Methods Enzymol. 186b, 407–421.
Schonberg, S., and Krokan, H.E. (1995) The Inhibitory Effect of Conjugated Dienoic Derivatives (CLA) of Linoleic Acid on the Growth of Human Tumour Cells Is in Part Due to Increased Lipid Peroxidation, Anticancer Res. 15, 1241–1246.
Cunningham, D.C., Harrison, L.Y., and Shultz, T.D. (1997) Proliferative Responses of Normal Human Mammary and MCF-7 Breast Cancer Cells to Linoleic Acid, Conjugated Linoleic Acid and Eicosanoid Synthesis Inhibitors in Culture, Anticancer Res. 17, 197–203.
Shultz, T.D., Chew, B.P., Seaman, W.R., and Luedecke, L.O. (1992) Inhibitory Effect of Conjugated Linoleic Acid Derivatives of Linoleic Acid and Beta Carotene on the in vitro Growth of Human Cancer Cells, Cancer Lett. 63, 125–133.
Ip, C., Briggs, S.P., Haegele, A.D., Thompson, H.J., Storkson, J., and Scimeca, J.A. (1996) The Efficacy of Conjugated Linoleic Acid in Mammary Cancer Prevention Is Independent of the Level or Type of Fat in the Diet, Carcinogenesis 17, 1045–1050.
Hayek, M.G., Han, S.N., Wu, D., Watkins, B.A., Meydani, M., Dorsey, J.L., Smith, D.E., and Meydani, S.N. (1999) Dietary Conjugated Linoleic Acid Influences the Immune Response of Young and Old C57BL/6NCrIBR Mice, J. Nutr. 129, 32–38.
Sebedio, J.L. (1997) Conjugated Linoleic Acid Metabolites in Rat, Biochim. Biophys. Acta 134, 35–42.
Pariza, M.W., Park, Y., Albright, K.J., Liu, W., Storkson, J.M., and Cook, M.E. Synthesis and Biological Activity of Conjugated Eicosadienoic Acid, Abstracts, 89th American Oil Chemists' Society Annual Meeting, May 10–13, 1998, Chicago, p. 21.
Sugano, M., Tsujita, A., Yamasaki, M., Yamada, K., Ikeda, I., and Kritchevsky, D. (1997) Lymphatic Recovery, Tissue Distribution, and Metabolic Effects of Conjugated Linoleic Acid in Rats, J. Nutr. Biochem. 8, 38–43.
Vasavi, H., Thangaraju, M., and Sachdanandam, P. (1994) Effect of α-Tocopherol on Lipid Peroxidation and Antioxidant System in Fibrosarcoma Bearing Rats, Mol. Cell. Biochem. 131, 125–129.
Nicolosi, R.J., Rogers, E.J., Kritchevsky, D., Scimeca, J.A., and Huth, P.J. (1997) Dietary Conjugated Linoleic Acid Reduces Plasma Lipoproteins and Early Aortic Atherosclerosis in Hypercholesterolaemic Hamsters, Artery 22, 266–277.
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Cantwell, H., Devery, R., O'Shea, M. et al. The effect of conjugated linoleic acid on the antioxidant enzyme defense system in rat hepatocytes. Lipids 34, 833–839 (1999). https://doi.org/10.1007/s11745-999-0430-4
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s11745-999-0430-4