Analysis Tools
muscle
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• soleus muscle fibers display a wrinkled and irregular sarcolemma, with more membrane invaginations per um of sarcolemma seen at 18 months than at 3 months of age
• i.p. injection of Evans blue dye (EBD) results in a >3-fold increase in the number of EBD+ fibers in diaphragm and plantaris muscles relative to control mice, indicating sarcolemma damage
• a similar increase in the number of EBD+ fibers is observed in plantaris muscle after mechanical overload
• however, no changes in serum creatine kinase activity are observed at baseline or at 1 month after mechanical overload
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• at 18 months of age, soleus muscles show minor irregularities in the organization of the myofibers with abnormal sarcomeres
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• at 18 months of age, soleus muscles show minor irregularities in the organization of the myofibers with abnormal sarcomeres
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• at 1 month after mechanical overload (OVL), plantaris muscle fibers show a larger mean muscle fiber diameter than OVL control fibers
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• at 12 weeks of age, about 3% of muscle fibers are centronucleated in tibialis anterior (TA) and soleus muscles relative to 0.4% in control mice, indicating focal skeletal muscle degeneration and regeneration
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• at 12 weeks of age, mice exhibit focal skeletal muscle degeneration
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• at 1 month after mechanical overload (OVL), plantaris muscle fibers show a switch towards a slower oxidative phenotype, with an increase in MHC2a-positive (oxidative) fibers and a decrease in MHC2b-positive (glycolytic) fibers relative to OVL control fibers
• in response to OVL, the level of reduction of MHC-2b-positive plantaris fibers is significantly greater than that in OVL control mice (-45.6% versus -21.9%, respectively)
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• at 1 month after mechanical overload (OVL), plantaris shows a higher muscle mass gain than OVL control muscle
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• under baseline (non-OVL) conditions plantaris muscles show a significantly higher number of Pax7+ satellite cells per 100 muscle fibers than non-OVL control muscles
• at 7 days after mechanical overload (OVL), Pax7+ satellite cell number is unchanged relative to that in non-OVL muscles, unlike in control muscles where the number of Pax7+ cells is significantly increased in response to OVL
• in the single-fiber culture model, satellite cells exhibit an enhanced capacity to express early myogenic differentiation markers
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• non-overload (non-OVL) plantaris muscles exhibit a significant decrease in maximal isometric force production (-19%) and fatigue resistance (-20%) in response to nerve stimulation relative to non-OVL control mice
• however, at 1 month after mechanical overload, OVL plantaris muscles show no differences in maximal force and fatigue resistance relative to OVL control mice
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• at 12 weeks of age, mice exhibit spontaneous muscle regeneration with centronucleated muscle fibers and small, newly regenerated muscle fibers stained by anti-neonatal MHC antibody in whole soleus and plantaris muscles
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growth/size/body
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• at 12 weeks of age, males fed a standard chow diet exhibit a slight increase in lean tissue (g) relative to controls
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• at 12 weeks of age, males fed a standard chow diet exhibit increased body length relative to controls
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homeostasis/metabolism
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• at 12 weeks of age, males fed a standard chow diet exhibit an increased oxygen consumption (mean VO2) relative to controls
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• at 12 weeks of age, males fed a standard chow diet exhibit an increase in mean heat relative to controls
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• mice show an increased hypertrophic response to mechanical overload in skeletal muscle with a higher level of increase in both maximal force and fatigue resistance relative to controls
• increased muscle remodeling capacity is characterized by muscle fibers switching to a more oxidative phenotype, reduced myostatin (Mstn) and atrogin (Fbxo32) mRNA levels, increased follistatin (Fst) mRNA levels, and higher levels of phosphorylated forms of signaling molecules implicated in muscle hypertrophy at 7 days after overload
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behavior/neurological
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• at 12 weeks of age, males fed a standard chow diet exhibit increased water intake relative to controls
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• at 12 weeks of age, males fed a standard chow diet exhibit increased spontaneous activity only at around 6 am
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skeleton
long tibia
(
J:268425
)
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• at 12 weeks of age, males fed a standard chow diet exhibit increased tibia length relative to controls
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limbs/digits/tail
long tibia
(
J:268425
)
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• at 12 weeks of age, males fed a standard chow diet exhibit increased tibia length relative to controls
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