title: Insulin resistance is not conserved in myotubes established from women with PCOS.
abstract: BACKGROUND
  Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among premenopausal women, who often develop insulin resistance. We tested the hypothesis that insulin resistance in skeletal muscle of patients with polycystic ovary syndrome (PCOS) is an intrinsic defect, by investigating the metabolic characteristics and gene expression of in vitro differentiated myotubes established from well characterized PCOS subjects.
  
  
  METHODS
  Using radiotracer techniques, RT-PCR and enzyme kinetic analysis we examined myotubes established from PCOS subjects with or without pioglitazone treatment, versus healthy control subjects who had been extensively metabolically characterized in vivo. Results. Myotubes established from PCOS and matched control subjects comprehensively expressed all insulin-sensitive biomarkers; glucose uptake and oxidation, glycogen synthesis and lipid uptake. There were no significant differences between groups either at baseline or during acute insulin stimulation, although in vivo skeletal muscle was insulin resistant. In particular, we found no evidence for defects in insulin-stimulated glycogen synthase activity between groups. Myotubes established from PCOS patients with or without pioglitazone treatment also showed no significant differences between groups, neither at baseline nor during acute insulin stimulation, although in vivo pioglitazone treatment significantly improved insulin sensitivity. Consistently, the myotube cultures failed to show differences in mRNA levels of genes previously demonstrated to differ in PCOS patients with or without pioglitazone treatment (PLEK, SLC22A16, and TTBK).
  
  
  CONCLUSIONS
  These results suggest that the mechanisms governing insulin resistance in skeletal muscle of PCOS patients in vivo are not primary, but rather adaptive.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00145340.
authors.affiliation: Department of Endocrinology, Odense University Hospital, Odense, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Eriksen
authors.forename: Ann Dorte
authors.initials: AD
authors.lastname: Pørneki
authors.forename: Vibe
authors.initials: V
authors.lastname: Skov
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Burns
authors.forename: Henning
authors.initials: H
authors.lastname: Beck-Nielsen
authors.forename: Dorte
authors.initials: D
authors.lastname: Glintborg
authors.forename: Michael
authors.initials: M
authors.lastname: Gaster
mesh_terms: D000328:Adult; D002454:Cell Differentiation; D005260:Female; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007333:Insulin Resistance; D007700:Kinetics; D050356:Lipid Metabolism; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D000077205:Pioglitazone; D011085:Polycystic Ovary Syndrome / Q000150:complications* / Q000628:therapy*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D045162:Thiazolidinediones / Q000494:pharmacology
chemical_list: D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D005947:Glucose; D000077205:Pioglitazone