title: Lack of effects of creatine on the regeneration of soleus muscle after injury in rats.
abstract: OBJECTIVE
  Creatine (Cr) supplementation may improve muscle functional capacity in patients with neuromuscular diseases, disuse atrophy, or muscular dystrophies. Activation of myogenic satellite cells has been reported to be enhanced by Cr both in vitro and in vivo. Therefore, we hypothesized that Cr supplementation may improve the early steps of regeneration after muscle injury and may accelerate the recovery of both muscle mass and phenotype.
  
  
  METHODS
  Degeneration of left soleus muscle was induced by notexin injection in rats supplemented or not with Cr. The mass of regenerated muscles was compared with contralateral intact muscles at days 1, 3, 7, 14, 21, 28, 35, and 42 after injury. We also studied protein levels of the proliferator cell nuclear antigen (PCNA) as a marker of cell proliferation, expression of myogenic regulatory factors (MRF) as a marker of differentiation, and the myosin heavy chain (MHC) profile and activities of citrate synthase (CS) and lactate dehydrogenase (LDH) isozymes as markers of muscle phenotype maturation.
  
  
  RESULTS
  Cr supplementation accelerated the recovery of muscle Cr content during the regeneration phase. Although there were no other differences between Cr-treated and nontreated rats, we observed that 1) regenerated muscle mass remained lower than that in intact muscle mass 42 d after injury, 2) PCNA and MRF expression strongly increased in regenerated muscles, 3) the MHC profile of regenerated muscles was recovered 28 d after injury, and 4) CS activity was fully recovered from day 14, whereas the specific H isozyme of lactate dehydrogenase activity remained lower than that in intact muscles until 42 d.
  
  
  CONCLUSIONS
  In contrast with results from in vitro studies, Cr supplementation had no effects in vivo on the time course of recovery of rat skeletal muscle mass and phenotype after notexin-induced injury.
authors: Department of Human Factors, National Health Research Center for Defense, France.
authors: Brigitte
authors: B
authors: Crassous
authors: Hélène
authors: H
authors: Richard-Bulteau
authors: Louise
authors: L
authors: Deldicque
authors: Bernard
authors: B
authors: Serrurier
authors: Marielle
authors: M
authors: Pasdeloup
authors: Marc
authors: M
authors: Francaux
authors: Xavier
authors: X
authors: Bigard
authors: Nathalie
authors: N
authors: Koulmann
mesh_terms: D000818:Animals; D003401:Creatine / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000293:injuries / Q000502:physiology*; D010641:Phenotype; D011257:Pregnancy Proteins / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000187:drug effects*
chemical_list: D011257:Pregnancy Proteins; C489178:Prl7d1 protein, rat; D003401:Creatine