Expression of glycogen synthase and glycogen content in skeletal muscles after administration of antiandrogens in endurance training of rats

Depletion of muscle glycogen is an accurate marker of the onset of exhaustion in aerobic physical exercise. Glyco­gen synthase (GS) catalyses the processes of addition of α-1,4 glucose units to the growing glycogen molecule. The type and utilisation of energy substrates used by muscles depend on the hormonal status and physical activity. There is a lack of data about the influence of androgens through their androgen receptor (АR) on glycogen con­tent and GS in aerobic exercise of skeletal muscles. The aim of the study was to investigate the effect of endurance training and the AR blocker on the glycogen con­tent and expression of GS in skeletal muscles. Wistar rats were allocated in trained and non-trained groups. The trained rats were subjected to submaximal training. Half of the trained and non-trained rats received Flutamide for 8 weeks. An immunohistochemical study for GS was carried out, as well as histological testing of glycogen through PAS-reaction, followed by mor­phometric and statistical analysis. Training increased glycogen content and immunoexpression of GS in soleus (Sol) and extensor digitorum lon­gus (EDL). АR blocking decreased glycogen content in Sol and GS immunoexpression in EDL of trained animals. The increased expression of GS found in trained rats reveals the role of the enzyme in adaptation processes in en­durance training. The lowered glycogen content in Sol after AR blocking in trained rats proves the participation of androgens through AR in adaptation to exercise. The lowered expression of GS after administration of antian­drogen in EDL after endurance training can be explained by differences in the AR content in the different types of skeletal muscles, which determines their response to androgens.