title: Unacylated ghrelin is associated with changes in insulin sensitivity and lipid profile during an exercise intervention.
abstract: OBJECTIVE
  Ghrelin has been implicated in energy homeostasis, body weight regulation and glucose metabolism. Level of unacylated ghrelin (UAG), but not acylated ghrelin (AG), has been suggested to increase during long-term exercise. However, the association of the level of UAG with exercise-induced changes of insulin sensitivity and lipid metabolism has not been previously investigated. We hypothesized that an increase in UAG level in response to a long-term exercise programme improves insulin sensitivity and associated lipid profile, independently of weight loss.
  
  
  METHODS
  A prospective study of 552 young men (mean age 19·3 and range 19-28 years) undergoing military service with structured 6-month exercise training programme. Exercise performance, clinical and biochemical measurements were obtained at baseline and follow-up. Association between UAG level and fasting glucose, insulin, insulin sensitivity and lipid levels were evaluated.
  
  
  RESULTS
  An overall increase in the level of UAG was observed during the 6-month follow-up (P < 0·001), which was largest among those with weight loss ≥ 2·5% or among those whose reduction in waist circumference was largest (P = 0·007 and P < 0·001, respectively). A change in UAG level correlated inversely with a change in fasting glucose and insulin levels, HOMA-IR, total cholesterol and total triglyceride levels (P < 0·001 for all). The association between change in the UAG level and the change in insulin sensitivity was independent of weight loss or reduction in waist circumference.
  
  
  CONCLUSIONS
  Increase in UAG level was associated with improved insulin sensitivity via mechanisms independent of weight loss during an intensive, long-term exercise intervention in young healthy men.
authors.affiliation: Institute of Health Sciences, Faculty of Medicine, University of Oulu, Finland. henna.cederberg@oulu.fi
authors.forename: Henna
authors.initials: H
authors.lastname: Cederberg
authors.forename: Vesa-Matti
authors.initials: VM
authors.lastname: Koivisto
authors.forename: Jari
authors.initials: J
authors.lastname: Jokelainen
authors.forename: Heljä-Marja
authors.initials: HM
authors.lastname: Surcel
authors.forename: Sirkka
authors.initials: S
authors.lastname: Keinänen-Kiukaanniemi
authors.forename: Ulla
authors.initials: U
authors.lastname: Rajala
mesh_terms: D000328:Adult; D000886:Anthropometry; D015444:Exercise / Q000502:physiology*; D054439:Ghrelin / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood*; D008297:Male; D008889:Military Personnel; D055815:Young Adult
chemical_list: D054439:Ghrelin; D008055:Lipids