Content area
Full text
Summary
This study aimed to investigate whether heat stress (HS) prevents a decrease in succinate dehydrogenase (SDH) activity and heat shock protein 60 (HSP60) and superoxide dismutase 2 (SOD2) contents in the extensor digitorum longus of streptozotocin (STZ)-induced diabetic rats. Twelve-week-old male Wistar rats were assigned to one of the four groups (n=6/group): control (Con), HS, diabetes mellitus (DM), and diabetes mellitus and heat stress (DM+HS). Diabetes was induced by the administration of STZ (50 mg/kg). HS was initiated 7 days after STZ treatment and performed at 42 °C for 30 min 5 times a week for 3 weeks. SDH activity was decreased in the DM and DM+HS groups. However, SDH activity was greater in the DM+HS group than in the DM group. Although HSP60 content was lower in the DM group than in the Con group, it was maintained in the DM+HS groups and was higher than that in the DM group. SOD2 content was decreased only in the DM group. These findings suggest that HS prevents the decrease in SDH activity in the skeletal muscle induced by DM. According to this mechanism, the maintenance of SOD2 and HSP60 by HS may suppress the increase in oxidative stress.
Key words
Diabetes mellitus Heat stress Succinate dehydrogenase Heat shock protein 60 Superoxide dismutase 2
Introduction
Diabetes mellitus (DM) is accompanied by a decrease in succinate dehydrogenase (SDH) activity, which is an important mitochondrial enzyme involved in energy metabolism, in skeletal muscle (He et al. 2001). Abnormalities of skeletal muscle energy metabolism, especially mitochondrial dysfunction, are associated with lowered exercise capacity (Okita et al. 1998, Yokota et al. 2011), which was also observed in patients with DM (Gürdal et al. 2015). Lowered exercise capacity in patients with DM is a predictor of mortality (Church et al. 2004). Hence, it is important for patients with DM to maintain SDH activity in skeletal muscle to prevent declines in exercise capacity.
Exercise, which is a standard intervention for DM patients, has a positive effect on SDH in skeletal muscle, but we believe that exercise can be problematic for some patients. Little et al. (2011) have reported that exercise increased respiratory complex II (known as SDH) in skeletal muscle of DM patients. However, the ability to perform moderate exercise...