title: Resistin acutely impairs insulin-stimulated glucose transport in rodent muscle in the presence, but not absence, of palmitate.
abstract: Resistin is a cytokine implicated in the development of insulin resistance. However, there has been little investigation of the effects of resistin on fatty acid (FA) metabolism and insulin response in skeletal muscle, a key tissue for glucose disposal. The purpose of the present study was to examine the role of altered FA metabolism as a cause of resistin's inhibition of insulin-stimulated glucose transport in muscle. Isolated rat soleus muscles were incubated acutely (2 h) in the presence or absence of 600 ng/ml resistin, with or without 2 mM palmitate. Resistin acutely impaired insulin-stimulated glucose transport and Akt phosphorylation, but only in the presence of palmitate, implicating a role for altered FA metabolism. This impairment of glucose transport induced by resistin plus palmitate could be pharmacologically rescued by the inclusion of aimidazole carboxamide ribonucleotide, a stimulator of AMP-activated protein kinase and FA oxidation, as well as inhibitors of ceramide synthesis (myriocin, fumonisin). However, to our surprise, resistin actually blunted the palmitate-induced increase in muscle ceramide content; as expected, ceramide content was significantly lowered by fumonisin. In summary, the acute impairment of insulin response by resistin was manifested only in the presence of high palmitate and was alleviated when FA metabolism was manipulated (increased oxidation, inhibited ceramide synthesis). Resistin's acute impairment of insulin response does not appear to require an absolute increase in ceramide content; however, reducing ceramide content alleviated the impairment in glucose transport and insulin signaling.
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, Canada N1G 2W1.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Junkin
authors.forename: David J
authors.initials: DJ
authors.lastname: Dyck
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Mullen
authors.forename: Adrian
authors.initials: A
authors.lastname: Chabowski
authors.forename: A Brianne
authors.initials: AB
authors.lastname: Thrush
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002518:Ceramides / Q000378:metabolism; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D005260:Female; D037341:Fumonisins / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D052243:Resistin / Q000378:metabolism*; D012265:Ribonucleotides / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002518:Ceramides; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D005229:Fatty Acids, Monounsaturated; D037341:Fumonisins; D007328:Insulin; D052243:Resistin; D012265:Ribonucleotides; D019308:Palmitic Acid; D000620:Aminoimidazole Carboxamide; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose; C001996:thermozymocidin