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Delayed Activation of Muscle Protein Synthesis following Resistance Exercise in Mice is mTORC1‐Dependent
Author(s) -
Aguirre Nicholas,
Baar Keith
Publication year - 2015
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.29.1_supplement.825.13
Subject(s) - anabolism , hindlimb , endocrinology , medicine , mtorc1 , puromycin , muscle hypertrophy , chemistry , western blot , resistance training , sciatic nerve , skeletal muscle , phosphorylation , protein biosynthesis , protein kinase b , biochemistry , gene
The activation of the mechanistic target of rapamycin‐complex‐1 (mTORC1) is important for muscle hypertrophy following resistance exercise. However, our present understanding of the dynamics of anabolic signaling and muscle protein synthesis (MPS) following an acute bout of resistance exercise in mice is lacking. PURPOSE: To determine the time course of anabolic signaling and MPS in response to an acute bout of resistance exercise in mice. METHODS: Three month old C57BL/6 mice (n = 56) were anesthetized, the sciatic nerve exposed before the point of trifurcation, and all of the muscles of the right distal hindlimb were stimulated for 10 sets of 6 repetitions with 1 minute rest between sets. Both control and stimulated tibialis anterior (TA) muscles were collected 0, 0.75, 1.5, 3, 4.5, 6, 9, 12 and 24 hours post‐loading. Thirty minutes prior to collection animals were injected with 100 μL of 0.04 μmol/g puromycin. Two additional groups of mice were injected with 110 μL of 1.5 μg/g rapamycin or saline immediately prior to loading and collected 6h later. Muscles were processed for western blot analysis of proposed anabolic signaling molecules and MPS via SUnSET. RESULTS: ERK1/2 phosphorylation peaked at 0.75h (2.76 ± 0.60) and pS6K1 Thr389 was significantly higher 1.5h (4.18 ± 2.75) and 3h (5.39 ± 0.62) post‐loading (p < 0.05). MPS showed two peaks, the first at 0.75h (1.27 ± 0.14) and the second at 6h (1.27 ± 0.10) post‐loading. Rapamycin abolished the peak at 6h even though mTORC1 activity was not elevated at this timepoint. CONCLUSION Following acute resistance exercise in mice, there are two peaks of anabolic activity. The first corresponds with an increase in ERK1/2 activity 0.75h after loading and the second, at 6h, is dependent on mTORC1 activation.