title: Joint inflammation alters gene and protein expression and leads to atrophy in the tibialis anterior muscle in rats.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of tibiotarsal joint inflammation in rat tibialis anterior muscle through muscle fiber cross-sectional area (CSA) and gene expression (atrogin-1, muscle ring finger-1 [MuRF1], myogenic differentiation-1 [MyoD], p38 mitogen-activated protein kinase [p38MAPK], nuclear factor kappa B-dependent [NFκB], tumor necrosis factor-alpha [TNF-α]).
  
  
  METHODS
  Wistar rats were randomly divided into three periods (2, 7, and 15 days) and assigned into four groups within each experimental period: control, sham, inflammation, and immobilization. Real-time polymerase chain reaction, Western blot, immunofluorescence, and muscle fiber CSA analyses were performed.
  
  
  RESULTS
  At 2 days, the inflammation group increased atrogin-1, MuRF1, and myostatin and reduced MyoD expression. At 7 days, the inflammation group increased atrogin-1, MuRF1, NFκB, p38MAPK, MyoD, myostatin, and TNF-α expression and TNF-α protein and reduced muscle fiber CSA. At 15 days, gene and protein expression in the inflammation group returned to basal levels, and CSA values were similar to those in control and sham groups. The immobilization groups have a similar pattern in all experimental periods, with increased atrogin-1, MuRF1, NFκB, and TNF-α gene expression and reduced muscle fiber CSA. The sham group had increased myostatin and atrogin-1 expression at 2 days and increased MyoD and myostatin expression at 7 days.
  
  
  CONCLUSIONS
  Joint inflammation stimulated the expression of muscle factors related to atrophy, growth, differentiation, and mass regulation followed by muscle atrophy.
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
authors.forename: Carolina
authors.initials: C
authors.lastname: Ramírez
authors.forename: Thiago Luiz
authors.initials: TL
authors.lastname: Russo
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Sandoval
authors.forename: Adriana Abbade
authors.initials: AA
authors.lastname: Dentillo
authors.forename: Marcela Abreu Silva
authors.initials: MA
authors.lastname: Couto
authors.forename: João Luiz Quagliotti
authors.initials: JL
authors.lastname: Durigan
authors.forename: Tania Fátima
authors.initials: TF
authors.lastname: Salvini
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007249:Inflammation / Q000473:pathology*; D008853:Microscopy; D018485:Muscle Fibers, Skeletal; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D009133:Muscular Atrophy / Q000473:pathology*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D055435:Myostatin / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D013640:Tarsal Joints / Q000473:pathology*; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: C525913:Mstn protein, rat; D009124:Muscle Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D055435:Myostatin; D016328:NF-kappa B; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha; C486691:Fbxo32 protein, mouse; D044843:SKP Cullin F-Box Protein Ligases; C499086:Trim63 protein, rat; D044767:Ubiquitin-Protein Ligases; D048051:p38 Mitogen-Activated Protein Kinases