High-intensity Exercise Training Attenuates Diabetes-induced Muscle Capillary Regression In Non-obese NIDDM Rats

Abstract

Exercise has been shown to be an effective non-pharmacological treatment in the prevention of some disease complications due to type 2 diabetes mellitus (T2DM). PURPOSE: The purpose of this study was to explore the effects of high-intensity running exercise on the 3-D microangiopathic structural changes of the capillary networks and associated angiogenic factors in the soleus muscle of non-obese T2DM rats. METHODS: Male Goto-Kakizaki (6 weeks old) spontaneously non-obese diabetic rats were used as a model of non-insulin dependent diabetes mellitus (NIDDM). Three groups of rats were studied: sedentary diabetic (T2DM), exercised diabetic (T2DM+Ex), and age-matched sedentary non-diabetic control (Con, wild-type Wistar) rats. The exercised rats were run at a relatively high-intensity (lactate > 9 mmol/L) on a treadmill. This protocol consisted of running at 20 m/min at a 20° incline for 30 min /session, 5 sessions /week for 3 weeks. The capillary network of the soleus muscle was visualized using confocal laser microscopy. The mRNA expression levels of several angiogenic factors (VEGF, KDR, Flt-1, Ang-1, Ang-2, Tie-2, and HIF-1 alpha) were determined in the soleus by TaqMan probe-based real-time PCR. RESULTS: Both T2DM and T2DM+Ex rats had higher levels of plasma glucose and glycohemoglobin compared to Con rats. The level of reactive oxygen species was higher in T2DM+Ex than Con and T2DM rats. The capillary volume of the soleus was lower in T2DM than Con rats. In contrast, the capillary volume was higher in T2DM+Ex than Con and T2DM rats. In addition the expression levels of all angiogenic factors in the soleus were lower in T2DM than Con and T2DM+Ex rats, except for VEGF and Ang-1 which were similar to Con rats. Furthermore, all values were higher in the T2DM+Ex than Con and T2DM rats. CONCLUSIONS:The present results indicate that high-intensity running exercise training reduces muscle circulatory complications associated with NIDDM in rats.