title: Increased IGF mRNA in human skeletal muscle after creatine supplementation.
abstract: OBJECTIVE
  We hypothesized that creatine supplementation would facilitate muscle anabolism by increasing the expression of growth factors and the phosphorylation of anabolic signaling molecules; we therefore tested the responses of mRNA for IGF-I and IGF-II and the phosphorylation state of components of anabolic signaling pathways p70(s6k) and 4E-BP1 to a bout of high-intensity resistance exercise after 5 d of creatine supplementation.
  
  
  METHODS
  In a double-blind cross-over design, muscle biopsies were taken from the m. vastus lateralis at rest and 3 and 24 h postexercise in subjects who had taken creatine or placebo for 5 d (21 g x d(-1)). For the first 3 h postexercise, the subjects were fed with a drink containing maltodextrin (0.3 g x kg(-1) body weight x h(-1)) and protein (0.08 g x kg(-1) body weight x h(-1)).
  
  
  RESULTS
  After creatine supplementation, resting muscle expressed more mRNA for IGF-I (+30%, P < 0.05) and IGF-II (+40%, P = 0.054). Exercise caused an increase by 3 h postexercise in IGF-I (+24%, P < 0.05) and IGF-II (+48%, P < 0.05) and by 24 h postexercise in IGF-I (+29%, P < 0.05), but this effect was not potentiated by creatine supplementation. The phosphorylation states of p70(s6k) and 4E-BP1 were not affected by creatine at rest; phosphorylation of both increased (150-400%, P < 0.05) to similar levels under placebo and creatine conditions at 3 h postexercise plus feeding. However, the phosphorylation state of 4E-BP1 was higher in the creatine versus placebo condition at 24 h postexercise.
  
  
  CONCLUSIONS
  The increase in lean body mass often reported after creatine supplementation could be mediated by signaling pathway(s) involving IGF and 4E-BP1.
authors.affiliation: Department of Physical Education and Rehabilitation, Faculty of Medicine, Catholic University of Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Louise
authors.initials: L
authors.lastname: Deldicque
authors.forename: Magali
authors.initials: M
authors.lastname: Louis
authors.forename: Daniel
authors.initials: D
authors.lastname: Theisen
authors.forename: Henri
authors.initials: H
authors.lastname: Nielens
authors.forename: Mischaël
authors.initials: M
authors.lastname: Dehoux
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Thissen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rennie
authors.forename: Marc
authors.initials: M
authors.lastname: Francaux
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D001706:Biopsy; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins; D003401:Creatine / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D013997:Time Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; D010750:Phosphoproteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D003401:Creatine