Skeletal Muscle Characteristics of Rats with Obesity, Diabetes, Hypertension, and Hyperlipidemia

Abstract

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. The mRNA expression levels of peroxisome proliferator-activated receptors (PPARalpha and PPARdelta/beta), PPARgamma coactivator-1alpha (PGC-1alpha), stearoyl-CoA desaturase-1 (SCD-1), carnitine palmi-toyl-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. GK rats showed lower PPARdelta/beta, PGC-1alpha, and MCAD expression levels than WR rats. SHR rats showed higher PPARalpha and MCAD and lower PPARdelta/beta expression levels than WR rats. CP rats showed lower PPARdelta/beta 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. The skeletal muscles of rats with lifestyle-related diseases have unique mRNA expres-sion patterns and fiber profiles depending on the type of disease. For example, the lower PGC-1alpha 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.