The Influence of Alpha-Lipoic Acid on Fiber Type Distribution and Cross Sectional Area of Rat Diabetic Skeletal Muscle

Background and Aims: Morphological changes of diabetic skeletal muscles are induced by diabetic neuropathy. Increased oxidative stress and impaired antioxidant defense are important machanisms in the pathogenesis of diabetic neuromyopathy. Since it has been demonstrated that alpha-lipoic acid (LA) is a potent biological antioxidant the aim of our study was to determine the influence of alpha-lipoic acid on the the process of muscle regeneration. Material and methods:Two-months-old male Wistar rats were made diabetic by a single intraperitoneal injection of streptozotocin (STZ). Regeneration process was induced in slow (m.soleus, SOL) and fast (m.extensor digitorum longus, EDL) muscles by injection of local anesthetic (bupivacain). All groups of rats (control, untreated diabetic and treated diabetic) were treated with LA (50 mg/kg). Skeletal muscles were analysed (fibre cross areas and fibre type distribution) 10 days, 4 and 8 weeks after bupivacaine treatment. Results: M. Soleus - After 4 weeks of diabetes the percentage of type I fibers in SOL muscles was significantly lower in respect to control group, while the percentage of type I and IIA of muscle fibers in the diabetic group treated with LA was similar to these in control group. The fibre cross areas of type IIA diabetic muscle fibers are significant smaller in respect to normal muscles. After 4 weeks of treatment, the fibre cross areas of type I and type IIA diabetic muscle fibers were significantly higher. M. Extensor Digitorum Longus - Diabetic untreated muscles, 4 weeks after regeneration, showed statisticaly increased percentage of type IIX fibers. In diabetic EDL muscles treated with LA were statisticaly more fibers type I and IIB. The cross areas of all fibre types in diabetic EDL muscles were significantly smaller than in control muscles. In diabetic group treated with LA the fibre cross areas were significantly higher than in diabetic group. Conclusions: These results suggest that treatment with LA can restore fiber type distribution and cross sectional areas induced by diabetes mellitus in regenerating slow and fast skeletal muscles.