1 3 J Endocrinol Invest DOI 10.1007/s40618-017-0720-0 ORIGINAL ARTICLE The effects of alpha-lipoic acid on diabetic myopathy D. Jurisic-Erzen 1 · G. Starcevic-Klasan 2 · D. Ivanac 3 · S. Peharec 4 · D. Girotto 5 · R. Jerkovic 2 Received: 16 November 2016 / Accepted: 22 June 2017 © Italian Society of Endocrinology (SIE) 2017 dominant in both slow and fast muscles. Muscle atrophy is present in all fiber types except in type I of slow skeletal muscle. Treatment with ALA reduce changes in the mor- phological properties caused by diabetes mellitus type 1 in slow and fast rat skeletal muscles during the process of regeneration. Conclusion Treatment with lipoic acid during 4 weeks has shown effects on the redistribution of muscle fibers, and can prevent atrophy in slow and fast diabetic muscle. Keywords Skeletal muscle · Regeneration · Diabetes mellitus type 1 · Alpha-lipoic acid Introduction Streptozotocin (STZ)-induced diabetes mellitus type 1 is the most commonly used animal model to study human diabetes mellitus. This model of insulin deficiency enables the investigation of physiological and pathological changes produced in skeletal muscle during the progression of dia- betes, known as diabetic neuromyopathy [1]. Diabetes mel- litus type 1 decrease skeletal muscle contractility, reduces regeneration capacity and induces muscle atrophy [2–4]. Histochemical and morphometric profiles of diabetic skele- tal muscles have been analyzed, showing a shift in myofiber composition in both fast and slow skeletal muscles [5, 6]. The skeletal muscle which is composed of heterogene- ous population of muscle fibers (type I, IIA, IIX and IIB) has the ability to complete a rapid and extensive regenera- tion in response to severe damage [7, 8]. During the pro- gression of diabetes mellitus, the regeneration capacity of skeletal muscle is impaired. Experimental model com- monly used in the study of muscle regeneration is induc- tion of muscle regeneration by intramuscular injection of Abstract Purpose Increased oxidative stress and impaired antioxi- dant defense are important mechanisms in the pathogen- esis of diabetic myopathy. Since diabetes mellitus type 1 decreases muscle regeneration capacity the present study was designed to determine the influence of alpha-lipoic acid (ALA), a potent biological antioxidant, on the process of regeneration of diabetic rat skeletal muscles. Methods 40 Wistar rats were divided into three groups: control (n = 8), untreated diabetic group (n = 16) and ALA treated diabetic group (n = 16). The regeneration process was provoked in streptozotocin-induced diabetic rats in both slow (m.soleus, SOL) and fast (m.extensor digitorum longus, EDL) skeletal muscles by intramuscular injection of myotoxin bupivacaine. At intervals of 10 days and 4 weeks, muscle histochemical and morphometrical analysis (fiber cross areas and fiber type distribution) was performed. Results Changes induced by diabetes are evident in redis- tribution of muscle fibers and in significant level of atro- phy. After 4 weeks of diabetes, glycolytic muscle fibers are * G. Starcevic-Klasan gordanask@medri.uniri.hr 1 Department of Internal Medicine, Clinical Hospital Centre Rijeka, Kresimirova 42, 51000 Rijeka, Croatia 2 Department of Anatomy, Faculty of Medicine, University of Rijeka, Brace Branchetta 20, 51000 Rijeka, Croatia 3 Department of Traumatology, Clinical Hospital Centre Rijeka, Tome Strizica 3, 51000 Rijeka, Croatia 4 Polyclinic of Physical Medicine and Rehabilitation, Rizzijeva 101, 52000 Pula, Croatia 5 Department of Neurosurgery, Clinical Hospital Centre Rijeka, Tome Strizica 3, 51000 Rijeka, Croatia