Effects of chronic high-fat feeding on skeletal muscle mass and function in middle-aged mice.

Abstract

Increased adipose tissue may promote catabolic events in skeletal muscle. The aim of this study was to test whether high-fat diet (HFD)-induced obesity would accelerate the onset of muscle wasting in middle-aged mice. Muscle was collected from C57BL/6 mice at 9months of age (baseline) and 14months of age after consuming a control (C) or HFD. Mice in C and HFD were also subjected to evaluations of body composition and function before and after their respective diets. HFD demonstrated significant (p<0.05) losses of grip strength (-15%) and sensorimotor coordination (-11%), whereas C did not. Lean mass decreased to a greater degree in HFD although not significantly (C: -20.69±7.94 vs. HFD: -31.14±5.49%, p>0.05). Gastrocnemius, quadriceps, and hamstrings mass in C and HFD were significantly reduced from baseline (-27 to 43 and -39 to 47%, respectively, p<0.05) with no differences between the two; however, soleus mass was lower only in HFD (-24%, p=0.03). Myofiber area, satellite cells, and myonuclei of the gastrocnemius were lower only in HFD (-23, -19, and -16%, respectively, p<0.05) compared to baseline. HFD-induced obesity adversely affected function in middle-aged mice. Atrophy of the soleus in HFD but not C suggests sensitivity of oxidative muscle to HFD-dependent catabolism more so than aging. In the muscles containing fast/mixed fibers, aging effects may have concealed the catabolic nature of HFD; however, morphological changes in the gastrocnemius including decreased fiber area, satellite cells, and myonuclei are consistent with an atrophic phenotype related to HFD.