engleski

Muscle regeneration capacity during the long-term experimental diabetes mellitus type 1

Background and Aims: Muscle fibers are dynamic structures capable of altering their phenotype under various physiological and pathological conditions. Skeletal muscle is composed of different fiber types (type I, IIA, IIX and IIB) with unique metabolic and contractile characteristics. Diabetes mellitus changes histochemical and morphometrical characteristics of skeletal muscle because of the influence on many neurogenic and myogenic factors. The progression of diabetes mellitus is concomitant with decrease of the regenerative capacity of skeletal muscle and treatment with insulin can prevent further atrophy of slow and fast skeletal muscles. This study was intended to explore the effects of type 1 diabetes and its treatment with insulin plus antioxidant (alpha-lipoic acid - LA) on the the process of skeletal muscle regeneration because oxidative stress have been implicated in pathogenesis of diabetic myopathy. Material and methods: Diabetes was induced by a single streptozotocin (STZ) 65 mg/kg with i.p. injection. Two-months-old male Wistar rats were randomized to control group, untreated diabetes group, diabetes group treated with insulin and diabetes group treated with insulin plus LA (50 mg/kg once daily). Regeneration process was induced in slow (m.soleus, SOL) and fast (m.extensor digitorum longus, EDL) muscles by injection of local anesthetic (bupivacain). The morphometric analysis (fibre cross areas and fibre type distribution) of skeletal muscles was performed after 10 days and 4 weeks. Results: Soleus muscle. In control group fiber, after 4 weeks of regeneration type distribution was similar to normal SOL without the regeneration. In the same period diabetic muscles, the percentage and the fibre cross areas of type I and IIA, did not reach values of control and normal SOL without the process of regeneration. In the group treated with insulin and insulin plus LA, the morphometric analysis of muscle was similar to these in control group. Extensor digitorum longus After 4 weeks of experiment control muscles were completely regenerated. In diabetic untreated muscles after 4 weeks of diabetes the percentage of type I and IIA fibers was greater. The treatment with insulin and insulin plus LA prevented changes in fiber type distribution during all investigated periods. Insulin therapy, in all experimental periods, resulted in a significant increase in fibre cross areas all fibre types. Additional therapy with LA leaded to better correction of the cross areas all fibre types like in control group and normal SOL without the process of regeneration. Conclusion: The additional use of antioxidant therapy with insulin has the potential benefit in the treatment of diabetic myopathy.

skeletal muscle; regeneration; diabetes mellitus

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