Aim: Data on the skeletal muscle characteristics of patients and animals with lifestyle-related diseases are limited. We investigated mRNA expression levels and fiber profiles in the skeletal muscles of rats with obesity, diabetes, hypertension, and/or hyperlipidemia. Methods: The mRNA expression levels of peroxisome proliferator-activated receptors (PPAR and PPAR / ), PPAR coactivator-1 (PGC-1 ), stearoyl-CoA desaturase-1 (SCD-1), carnitine palmitoyl-transferase (CPT ), medium-chain acyl-CoA dehydrogenase (MCAD), and mitochondrial transcriptional factor A (TFAM) in the soleus muscles were compared among 15-week-old control (WR), type 2 diabetic (GK), hypertensive (SHR), and hyperlipidemic (CP) rats. The fiber profiles in the soleus muscles of these rats were also determined. Results: GK rats showed lower PPAR / , PGC-1 , and MCAD expression levels than WR rats. SHR rats showed higher PPAR and MCAD and lower PPAR / expression levels than WR rats. CP rats showed lower PPAR / and higher SCD-1 expression levels than WR rats. The muscles of WR, SHR, and CP rats had low-oxidative type and high-oxidative type A and type C fibers, whereas the muscle of GK rats had only low-oxidative type fibers.
Conclusions:The skeletal muscles of rats with lifestyle-related diseases have unique mRNA expression patterns and fiber profiles depending on the type of disease. For example, the lower PGC-1 and MCAD mRNA expression levels in the soleus muscles of type 2 diabetic rats are associated with the presence of only low-oxidative type fibers in the muscle.
J Atheroscler Thromb, 2009; 16:576-585.Key words; Lifestyle-related disease, mRNA expression level, Muscle fiber type bility of ATPase at acidic pH. Type A fibers become ATPase negative at a faster rate than type B fibers when the acidity of the preincubation medium increases. Type C fibers have been identified in skeletal muscles, particularly in the soleus muscle of rats; these fibers are ATPase positive, irrespective of the pH of the preincubation medium. Glycolytic enzyme activity is higher in type A, type B, and type C fibers than in type fibers, whereas oxidative enzyme activity is higher in type , type A, and type C fibers than in type B fibers; therefore, the presence of different types of fibers correlates with the metabolic properties of individual skeletal muscles. Skeletal muscles exhibit plasticity and undergo fiber type transitions under various conditions, such as growth, aging,