title: Changes in skeletal muscle proteolytic gene expression after prophylactic supplementation of EGCG and NAC and eccentric damage.
abstract: OBJECTIVE
  The impact of prophylactic supplementation of N-acetyl-cysteine (NAC) and epigallocatechin gallate (EGCG) on intramuscular expression of proteolytic genes after unaccustomed eccentric muscle contractions was investigated.
  
  
  METHODS
  Thirty apparently healthy males (mean ± SD: 20.0 ± 1.8 years, 175 ± 7.1cm, 76.1 ± 16.9 kg) ingested daily either 1,800 mg of NAC or 1,800 mg of EGCG (98% total polyphenols, 80% total catechins, and 50% EGCG), or 1,000 mg of a glucomannan placebo (PLA) in a double blind, prophylactic fashion for 14 days. Subjects then completed an unaccustomed eccentric exercise bout (100 repetitions at 30 °s(-1)) using the dominant knee extensors. Skeletal muscle biopsies were collected from the vastus lateralis at baseline and both 6 and 24h after exercise. The expression of proteolytic genes [i.e., muscle ring-finger 1 (MuRF1), atrogin-1, α-type 20S subunit C2 (HC2), α-type 20S subunit C3 (HC3), ubiquitin protein ligase 3B (UBE3B), μ-calpain, and m-calpain] was quantified using real-time RT-PCR. Separate 3 × 3 (group × time) repeated measures ANOVAs were used to analyze changes in gene expression over time between groups.
  
  
  RESULTS
  No significant group × time interactions were detected between groups for the expression of any of the atrogenes or calpains (p>0.05). Significant main effects for time identified increases in MuRF1 (6h: 5.3 ± 10.8 fold; p=0.046), UBE3B (6h: 5.3 ± 7.7 fold; p=0.006; 24h: 3.3 ± 4.5 fold; p=0.005), and m-calpain expression (6h: 2.7 ± 4.4 fold; p=0.045) in all participants following exercise. Increases approached significance in HC2 (6h: 1.9 ± 2.4 fold; p=0.079; 24h: 1.6 ± 1.9 fold; p=0.084) and m-calpain expression (24h: 1.8 ± 2.3 fold; p=0.084) following exercise.
  
  
  CONCLUSIONS
  Prophylactic supplementation of NAC and EGCG did not impact acute changes in skeletal muscle proteolytic gene expression following eccentric exercise. Eccentric muscle contractions elevated MuRF1 and UBE3B, while m-calpain and HC2 mRNA tended to increase.
authors: Department of Health, Exercise and Sports Sciences, Exercise Physiology Lab, MSC04 2610, Room B145, University of New Mexico, Albuquerque, NM 87131, United States.
authors: Chad M
authors: CM
authors: Kerksick
authors: Michael D
authors: MD
authors: Roberts
authors: Vincent J
authors: VJ
authors: Dalbo
authors: Richard B
authors: RB
authors: Kreider
authors: Darryn S
authors: DS
authors: Willoughby
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D002154:Calpain / Q000235:genetics; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D019587:Dietary Supplements; D004311:Double-Blind Method; D015444:Exercise; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D033281:Nontherapeutic Human Experimentation; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D055815:Young Adult
chemical_list: D009124:Muscle Proteins; D000070584:Tripartite Motif Proteins; D002392:Catechin; C045651:epigallocatechin gallate; C482647:UBE3B protein, human; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; C440908:TRIM63 protein, human; D044767:Ubiquitin-Protein Ligases; D002154:Calpain; C449000:m-calpain; C449002:mu-calpain; D000111:Acetylcysteine
keywords: EGCG; N-acetyl-cysteine; Proteolysis; Skeletal muscle