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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #234333
Title: Differential effects of chronic overload-induced muscle hypertrophy on mTOR and MAPK signaling pathways in adult and aged rats

Author
item CHALE-RUSH, ANGELA - JM USDA HNRCA @ TUFTS
item MORRIS, EVAN - JM USDA HNRCA @ TUFTS
item KENDALL, TRACEE - NOVARTIS INST BIOMED RES
item Fielding, Roger
item BROOKS, NAOMI - UNIV OF STELLENBOSCH

Submitted to: FASEB Letters
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2008
Publication Date: 4/1/2009
Citation: Chale-Rush, A., Morris, E.P., Kendall, T.L., Fielding, R., Brooks, N.E. 2009. Differential effects of chronic overload-induced muscle hypertrophy on mTOR and MAPK signaling pathways in adult and aged rats [abstract]. FASEB Letters. 23:954.3

Interpretive Summary:

Technical Abstract: We examined activation of the mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) signaling pathways in adult (Y; 6 mo old; n = 16) and aged (O; 30 mo old; n = 16) male rats (Fischer 344 x Brown Norway) subjected to chronic overload-induced muscle hypertrophy of the plantaris (PLA) and soleus (SOL) muscles. Animals underwent either 4 weeks of bilateral surgical ablation (SA) of two-thirds of the gastrocnemius muscle or sham surgery (CON). Animals were subjected to SA to promote compensatory hypertrophy in the PLA and SOL muscles. Muscle weights of the Y CON (434 +/- 39 mg; mean +/- SD; p < 0.05) and Y SA (506 +/- 56 mg) rats were significantly heavier than the O CON (353 +/- 18 mg) and O SA (402 +/- 41 mg) rats. There was a significant interaction between group and age for phosphorylated mTOR. Phosphorylated mTOR was higher in the Y SA group (4129 +/- 674 A.U.; mean +/- SE; p < 0.05) than in the Y CON (1582 +/- 674), O SA (2063 +/- 630) and O CON (2667 +/- 728) groups. The ratio of phosphorylated to total mTOR was significantly higher in both SA groups than in their respective controls (0.107 +/- 0.105 A.U. vs. -0.297 +/- 0.112; p < 0.05). We also observed a significant effect of age on total p44 MAPK. It was higher in the O (17969 +/- 1242; p < 0.05) than the Y (13342 +/- 1242) rats. These data indicate mTOR signaling is attenuated in an aging animal model of chronic overload-induced muscle hypertrophy.