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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #222079
Title: Chronic overload induced hypertrophy is associated with age-related muscle mass loss and diminished mTOR signaling

Author
item KENDALL, TRACEE - JM USDA HNRCA @TUFTS
item BROOKS, NAOMI - STELLENBOSCH UNIVERSITY
item Fielding, Roger

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2008
Publication Date: 4/1/2008
Citation: Kendall, T.L., Brooks, N.E., Fielding, R. 2008. Chronic overload induced hypertrophy is associated with age-related muscle mass loss and diminished mTOR signaling. Journal of Federation of American Societies for Experimental Biology. 22:959.15.

Interpretive Summary:

Technical Abstract: The purpose of this study was to assess activation of the mTOR signaling pathway in young and aging rats in response to chronic muscle overload. Young (6 mo; n = 16) and older (30 mo; n = 23) male rats (F344xBN) were subjected to 4 weeks of bilateral surgical ablation (SA) of two-thirds of the gastrocnemius muscle to promote compensatory hypertrophy in the plantaris (PLA) and soleus (SOL) or a sham surgery (CON). A significant interaction (p= 0.00) was found between group (SA vs. CON) and age (6mo. vs. 30mo.) when examining the normalized muscle weights (muscle weight/final body weight) of the PLA and SOL. The PLA muscle mass (mean +/- SD) following SA was heavier in young rats when compared to aging rats (1.34 +/- 0.07 g muscle weight/g body weight vs. 0.79 +/- 0.08; p=0.00). An equivalent pattern was observed in the SOL in response to SA (0.52 +/- 0.04 vs. 0.34 +/- 0.04; p=0.00). Phosphorylation of p70S6K in the SOL and PLA was similar in both young and aging rats when comparing SA (n=4) versus CON (n=4) (SOL: 6 mo; 0.21 +/- 0.14 A.U. vs. 0.10 +/- 0.10, 30mo; 0.20 +/- 0.19 vs. 0.10 +/- 0.06, PLA: 6 mo; 0.04 +/- 0.02 vs. 0.02 +/- 0.02, 30 mo; 0.06 +/- 0.06 vs. 0.05 +/- 0.01). These data indicate that aging muscle in rats is less responsive to hypertrophy in the PLA and SOL, which may be caused by impairment in mTOR signaling.