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Intramuscular NF‐κβ Signaling in Response to Resistance Exercise and Recovery in Untrained Males
Author(s) -
Townsend Jeremy,
Stout Jeffrey,
Jajtner Adam,
Church David,
Beyer Kyle,
Oliveira Leonardo,
Fukuda David,
Hoffman Jay
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1245.2
Subject(s) - squat , signal transduction , transcription factor , medicine , endocrinology , skeletal muscle , inflammation , chemistry , leg press , tumor necrosis factor alpha , resistance training , biochemistry , physiology , gene
The nuclear factor kappa B (NF‐κβ) signaling cascade is responsible for mediating stress‐activated catabolic effects of TNF‐α downstream of the TNF receptor. NF‐κβ transcription factor remains inhibited in the cytosol of the muscle and can be stimulated for translocation and transcription by a variety of external stimuli, most notably by pro‐inflammatory cytokines and oxidative stress. Nevertheless, currently there is a gap in the literature with regard to the time course effect of NF‐κβ signaling following acute resistance exercise in humans. PURPOSE To observe the effects of an acute lower‐body resistance exercise protocol and subsequent recovery on intramuscular NF‐κβ signaling. METHODS Twenty‐eight untrained males (22.3 ± 3.2 y, 1.7 ± 0.1 m, 81.1 ± 15.5 kg) were assigned to either a control (CON; n=11) or exercise group (EX; n=17) and completed a lower‐body resistance exercise protocol consisting of the back squat, leg press, and leg extension exercise. Skeletal muscle microbiopsies were obtained from the vastus lateralis pre‐exercise (PRE), 1‐hour (1HR), 5‐hour (5HR), and 48‐hours (48HR) post‐resistance exercise. Multiplex signaling assay kits (EMD Millipore, Billerica, MA, USA) were used to quantify the total protein (TNFR1, c‐Myc) or phosphorylation status of proteins (IKKa/b, NF‐κβ, IkB) specific to apoptotic signaling pathways using MAGPIX® (Luminex, Austin, TX, USA). Mann Whitney U analysis was used to determine the effects of the exercise bout on intramuscular signaling at each timepoint. Additionally, change scores were analyzed by magnitude based inferences to determine a mechanistic interpretation. RESULTS Mann‐Whitney U analysis revealed that resistance exercise increased total c‐Myc at 1H (p=0.001) and tended to increase with exercise (p=0.053) at 5H. A trend for an increase in IkB phosphorylation was observed at 5H (p=0.053). There were no other significant differences observed. Magnitude based inferences revealed a “Very Likely” increase in total c‐Myc from PRE‐5H and a “Likely” increase in IkB phosphorylation from PRE‐5H. CONCLUSION It appears that c‐Myc transcription factor and phosphorylation of IkB are elevated following acute intense resistance exercise in untrained males. These data may indicate that NF‐κβ signaling plays a role in skeletal muscle regeneration following resistance exercise in young untrained males.