title: Conjugated linoleic acid improves glucose utilization in the soleus muscle of rats fed linoleic acid-enriched and linoleic acid-deprived diets.
abstract: The effect that conjugated linoleic acid (CLA) has on glucose metabolism in experimental animals depends on nutritional conditions. Therefore, we hypothesized that CLA improves glucose utilization and insulin sensitivity in rats fed different levels of dietary linoleic acid (LA). We investigated the effect of CLA on the uptake, incorporation, and oxidation of glucose and glycogen synthesis in the soleus muscle of rats who were fed either LA-enriched (+LA) or LA-deprived (-LA) diets, under basal conditions and in the absence or presence of insulin and/or palmitate. For 60 days, male Wistar rats were fed 1 of 4 diets consisting of +LA, -LA, or +LA and -LA supplemented with CLA. Nutritional parameters and soleus glucose metabolism were evaluated. Under basal conditions, CLA enhanced soleus glucose oxidation, whereas increased glucose uptake and incorporation were observed in the -LA + CLA group. Conjugated linoleic acid-supplemented rats presented a lower response to insulin on glucose metabolism compared with non-CLA-supplemented rats. Palmitate partially inhibited the effect of insulin on the uptake and incorporation of glucose in the +LA and -LA groups but not in the +LA + CLA or -LA + CLA groups. Dietary CLA increased glucose utilization under basal conditions and prevented the palmitate-induced inhibition of glucose uptake and incorporation that is stimulated by insulin. The beneficial effects of CLA were better in LA-deprived rats. Conjugated linoleic acid may also have negative effects, such as lowering the insulin response capacity. These results demonstrate the complexities of the interactions between CLA, palmitate, and/or insulin to differentially modify muscle glucose utilization and show that the magnitude of the response is related to the dietary LA levels.
authors.affiliation: Cátedra Bromatología y Nutrición, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Fariña
authors.affiliation: Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, Sao Paulo, Brazil.
authors.forename: Sandro
authors.initials: S
authors.lastname: Hirabara
authors.affiliation: Cátedra Bromatología y Nutrición, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Santa Fe, Argentina.
authors.forename: Juliana
authors.initials: J
authors.lastname: Sain
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Santa Fe, Argentina.
authors.forename: María E
authors.initials: ME
authors.lastname: Latorre
authors.affiliation: Cátedra Bromatología y Nutrición, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Marcela
authors.initials: M
authors.lastname: González
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Rui
authors.initials: R
authors.lastname: Curi
authors.affiliation: Cátedra Bromatología y Nutrición, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Santa Fe, Argentina. Electronic address: cbernal@fbcb.unl.edu.ar.
authors.forename: Claudio
authors.initials: C
authors.lastname: Bernal
mesh_terms: D000818:Animals; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology*; D019587:Dietary Supplements; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D019787:Linoleic Acid / Q000008:administration & dosage / Q000172:deficiency / Q000494:pharmacology*; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D017208:Rats, Wistar
chemical_list: D004041:Dietary Fats; D007328:Insulin; D044243:Linoleic Acids, Conjugated; D019787:Linoleic Acid; D005947:Glucose
keywords: Conjugated linoleic acid; Glucose incorporation; Glucose oxidation; Glucose uptake; Glycogen synthesis; Linoleic acid; Rat