title: High-fat feeding reduced muscle uncoupling protein 3 expression in rats.
abstract: Uncoupling Protein 3 (UCP3), largely expressed in skeletal muscle, is modulated by cold, thyroid hormones, leptin, fasting-refeeding and exercise training among other factors in a tissue-specific manner. In brown adipose tissue, there is an increase in UCP3 levels after high-fat feeding and beta3-adrenergic agonist treatment. Controversial effects of these agents have been reported in skeletal muscle. The aim of this experimental trial was to evaluate the effect of high-fat feeding and beta3-adrenergic agent treatment on skeletal muscle UCP3 expression levels. Lean rats were fed a cafeteria diet for 30 days and found to have significantly higher fat stores and body weight than control rats at the end of the experimental period. When cafeteria-diet rats were daily i.p. injected with Tertatolol for 30 days; a decrease in total fat mass and body weight was found. Such an effect was not observed in fa/fa rats. Interestingly, gastrocnemius muscle UCP3 mRNA levels were significantly reduced in cafeteria-diet rats when compared to lean animals. Likewise, mitochondrial O2 consumption in gastrocnemius muscle was also significantly decreased (-31%) in cafeteria-diet rats as compared to the control group. It is suggested that the down-regulation of UCP3 gene expression together with the lower O2 consumption observed in high fat fed rats may be linked to lower fatty oxidation, which would promote triglyceride accumulation.
authors.affiliation: Departamento de Fisiología y Nutrición, Universidad de Navarra, Pamplona, Spain.
authors.forename: M S
authors.initials: MS
authors.lastname: Corbalán
authors.forename: J
authors.initials: J
authors.lastname: Margareto
authors.forename: J A
authors.initials: JA
authors.lastname: Martínez
authors.forename: A
authors.initials: A
authors.lastname: Marti
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D017931:DNA Primers; D004041:Dietary Fats / Q000008:administration & dosage*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007473:Ion Channels; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000235:genetics* / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011924:Rats, Zucker; D013876:Thiophenes; D000071247:Uncoupling Protein 3
chemical_list: D000319:Adrenergic beta-Antagonists; D002352:Carrier Proteins; D017931:DNA Primers; D004041:Dietary Fats; D007473:Ion Channels; D024101:Mitochondrial Proteins; D011412:Propanolamines; D012333:RNA, Messenger; D013876:Thiophenes; C000604394:Ucp3 protein, rat; D000071247:Uncoupling Protein 3; C005632:tertatolol