title: Effect of obesity and insulin sensitivity on adiponectin isoform distribution.
abstract: BACKGROUND
  Adiponectin is an insulin-sensitizing, antiatherogenic and anti-inflammatory adipocytokine that circulates in three isoforms: a trimer [low-molecular weight (LMW)], a hexamer (trimer-dimer) of medium molecular weight (MMW) and a multimeric high molecular weight (HMW) isoform. Evidence is accumulating that HMW adiponectin is the active isoform of the adipocytokine. We investigated the impact of adipose tissue and insulin sensitivity on adiponectin isoform distribution.
  
  
  METHODS
  One hundred and eighty-seven normolipidaemic, non-diabetic lean or obese subjects with or without insulin resistance participating in the Salzburg Atherosclerosis Prevention program in subjects at High Individual Risk (SAPHIR) were included in the study. Insulin sensitivity was determined by the short insulin tolerance test and the homeostasis model assessment (HOMA) index. Serum adiponectin isoform distribution was determined by an enzyme immunoassay.
  
  
  RESULTS
  Total adiponectin as well as HMW/total adiponectin ratio was significantly increased in female subjects. Circulating total adiponectin levels were lowest in obese patients due to reduced concentrations of HMW adiponectin. As determined by stepwise regression analysis, besides age and high density lipoprotein (HDL) cholesterol, visceral fat area and waist-to-hip ratio predicted concentrations of HMW adiponectin, while insulin sensitivity had no influence on either total adiponectin or its isoforms.
  
  
  CONCLUSIONS
  Our results underline that determination of adiponectin isoforms are more useful than measurement of total adiponectin in clinical settings. Our data suggest that adiponectin concentrations are strongly associated with visceral fat area but not with insulin sensitivity. Thus, we hypothesize that insulin resistance is a consequence rather than the cause of hypoadiponectinaemia in obese subjects.
authors.affiliation: Medical University Innsbruck, Department of Medicine, Clinical Division of General Internal Medicine, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Kaser
authors.forename: T
authors.initials: T
authors.lastname: Tatarczyk
authors.forename: A
authors.initials: A
authors.lastname: Stadlmayr
authors.forename: C
authors.initials: C
authors.lastname: Ciardi
authors.forename: C
authors.initials: C
authors.lastname: Ress
authors.forename: A
authors.initials: A
authors.lastname: Tschoner
authors.forename: A
authors.initials: A
authors.lastname: Sandhofer
authors.forename: B
authors.initials: B
authors.lastname: Paulweber
authors.forename: C F
authors.initials: CF
authors.lastname: Ebenbichler
authors.forename: J R
authors.initials: JR
authors.lastname: Patsch
mesh_terms: D052242:Adiponectin / Q000097:blood* / Q000737:chemistry; D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D005260:Female; D005690:Galactose / Q000031:analogs & derivatives; D006801:Humans; D007118:Immunoassay; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*
chemical_list: D052242:Adiponectin; C101225:trigalactose; D002784:Cholesterol; D005690:Galactose