Growth-Related Changes in Skeletal Muscle Fiber Type and Insulin Resistance in Diabetic Otsuka Long-Evans Tokushima Fatty Rats.

Abstract

We investigated whether a relationship exists between the fiber type distribution in skeletal muscles and the insulin resistance of different ages of diabetic rats. The fiber type distributions of the slow soleus and fast plantaris muscles in 5-, 9-, and 21-week-old male Otsuka LongEvans Tokushima Fatty (OLETF) rats as an animal model of spontaneous type 2 diabetes mellitus were examined and compared with those in age-matched nondiabetic Long-Evans Tokushima Otsuka (LETO) rats. In the soleus muscle, a higher percentage of type I fibers was observed in the 9-and 21-week-old OLETF rats compared with the age-matched LETO rats, and there were no type IIA fibers remaining in the soleus muscle of the OLETF rats. In the plantaris muscle, a lower percentage of type IIA fibers and a higher percentage of type IIB fibers were observed in the 9-and 21-week-old OLETF rats compared with the agematched LETO rats. In addition, a lower percentage of type I fibers in the plantaris muscle was observed in the 9-weekold OLETF rats compared with the agematched LETO rats, and there were no type I fibers in the plantaris muscle of the 21-week-old OLETF rats. All 20-weekold OLETF rats showed serum insulin concentrations of more than 20 ng/ml. The present study suggests that insulin resistance and impaired glucose tolerance from altered muscle fiber type are linked to the cause of diabetes.

Maxillofacial Deformity and Change in the Histochemical Characteristics of the Masseter Muscle after Unilateral Sectioning of the Facial Nerve in Growing Rabbits.

“…This conversion from type 1 to type 2A fibers may be caused by the reduction of load continuously resisted by the masseter muscle on the denervated side, occurring simultaneously with disuse atrophy of type 1 fibers. Conversion of slow fibers to fast fibers has previously been observed in the limb muscles [10,37] and during growth [20].…”

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

“…Patients with type 2 diabetes have a reduced number of high-oxidative fibers in their skeletal muscles [36][37][38] . This is linked with the glucose level because the growth-related increase in the glucose level in diabetic animals is associated with the number of low-oxidative fibers in skeletal muscles [39][40][41] . The mRNA expression level of PGC-1 in skeletal muscles is lower in diabetic patients than in healthy individuals 42) .…”

Hyperbaric Exposure with High Oxygen Concentration Improves Altered Fiber Types in the Plantaris Muscle of Diabetic Goto-Kakizaki Rats

“…Furthermore, the fiber oxidative enzyme activity increased after hyperbaric exposure, regardless of fiber type. It is concluded that altered patterns of fiber types in the plantaris muscle of diabetic rats shift toward normal, which is observed in nondiabetic rats, following hyperbaric exposure with high oxygen concentration.Key words: diabetes mellitus, hyperbaric oxygenation, plantaris muscle.Patients and animal models with type 2 diabetes mellitus exhibit altered patterns of fiber types in skeletal muscles [1][2][3][4][5]. Goto-Kakizaki rats, animal models of spontaneous type 2 diabetes mellitus [6], have a lower percentage of high-oxidative fibers in the slow soleus and fast plantaris muscles than age-matched nondiabetic rats [7].…”

“…Patients and animal models with type 2 diabetes mellitus exhibit altered patterns of fiber types in skeletal muscles [1][2][3][4][5]. Goto-Kakizaki rats, animal models of spontaneous type 2 diabetes mellitus [6], have a lower percentage of high-oxidative fibers in the slow soleus and fast plantaris muscles than age-matched nondiabetic rats [7].…”