Journal Article

Isomer-specific antidiabetic properties of conjugated linoleic acid. Improved glucose tolerance, skeletal muscle insulin action, and UCP-2 gene expression

YU, M, GALUSKA, D, ZIERATH, J. R, CUI, L, HOUSEKNECHT, K. L, BAUMAN, D. E, RYDER, J. W, SONG, X. M, CHARRON, M. J, COMBATSIARIS, T, PORTOCARRERO, C. P, BARBANO, D. M

2001

Overview

Conjugated linoleic acid (CLA) isomers have a number of beneficial health effects, as shown in biomedical studies with animal models. Previously, we reported that a mixture of CLA isomers improved glucose tolerance in ZDF rats and activated peroxisome proliferator-activated receptor (PPAR)-gamma response elements in vitro. Here, our aim was to elucidate the effect(s) of specific CLA isomers on whole-body glucose tolerance, insulin action in skeletal muscle, and expression of genes important in glucose and lipid metabolism. ZDF rats were fed either a control diet (CON), one of two CLA supplemented diets (1.5% CLA) containing differing isoforms of CLA (47% c9,t11; 47.9% c10,t12, 50:50; or 91% c9,t11, c9,t11 isomers), or were pair-fed CON diet to match the intake of 50:50. The 50:50 diet reduced adiposity and improved glucose tolerance compared with all other ZDF treatments. Insulin-stimulated glucose transport and glycogen synthase activity in skeletal muscle were improved with 50:50 compared with all other treatments. Neither phosphatidlyinositol 3-kinase activity nor Akt activity in muscle was affected by treatment. Uncoupling protein 2 in muscle and adipose tissue was upregulated by c9,t11 and 50:50 compared with ZDF controls. PPAR-gamma mRNA was downregulated in liver of c9,t11 and pair-fed ZDF rats. Thus, the improved glucose tolerance in 50:50 rats is attributable to, at least in part, improved insulin action in muscle, and CLA effects cannot be explained simply by reduced food intake.

• Publisher: American Diabetes Association
• Subject: Adipose Tissue - drug effects / Adipose Tissue - metabolism / Animals / Biological and medical sciences / Blood Glucose - drug effects / Blood Glucose - metabolism / Body fat / Body Weight - drug effects / Diabetes / Diabetes mellitus / Diet / Dietary Supplements / Energy Intake - drug effects / Fatty Acids, Nonesterified - blood / Feeding Behavior - drug effects / Feeding. Feeding behavior / Fundamental and applied biological sciences. Psychology / Gene Expression Regulation - drug effects / Glucose / Glucose Tolerance Test / Grants / Hyperglycemia / Insulin / Insulin - blood / Insulin - physiology / Ion Channels / Isomerism / Kinases / Leptin - blood / Linoleic acid / Linoleic acids / Linoleic Acids - administration & dosage / Linoleic Acids - pharmacology / Lipid metabolism / Male / Membrane Transport Proteins / Mitochondrial Proteins / Muscle, Skeletal - drug effects / Muscle, Skeletal - physiology / Musculoskeletal system / Phosphatidylinositol 3-Kinases - metabolism / Physiological aspects / Prevention / Protein-Serine-Threonine Kinases / Proteins - genetics / Proto-Oncogene Proteins - metabolism / Proto-Oncogene Proteins c-akt / Rats / Rats, Zucker / Receptors, Cytoplasmic and Nuclear - genetics / RNA, Messenger - genetics / Striated muscle / Transcription Factors - genetics / Transcription, Genetic - drug effects / Triglycerides - blood / Uncoupling Agents - metabolism / Uncoupling Protein 2 / Vertebrates: anatomy and physiology, studies on body, several organs or systems