Skeletal muscle characteristics of rats with obesity, diabetes, hypertension, and hyperlipidemia

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 (PPARα and PPARδ/β), PPARγ coactivator-1α (PGC-1α), stearoyl-CoA desaturase-1 (SCD-1), carnitine palmitoyl-transferase I (CPT I), 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 PPARδ/β, PGC-1α, and MCAD expression levels than WR rats. SHR rats showed higher PPARα and MCAD and lower PPARδ/β expression levels than WR rats. CP rats showed lower PPARδ/β and higher SCD-1 expression levels than WR rats. The muscles of WR, SHR, and CP rats had low-oxidative type I and high-oxidative type IIA and type IIC fibers, whereas the muscle of GK rats had only low-oxidative type I 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-1α and MCAD mRNA expression levels in the soleus muscles of type 2 diabetic rats are associated with the presence of only low-oxidative type I fibers in the muscle.