Stable Level of Giant Sarcomeric Cytoskeletal Proteins in Striated Muscles of the Edible Dormouse Glis glis during Hibernation

The changes in the content of the giant sarcomeric cytoskeletal proteins titin (3000–3700 kDa) and nebulin (770 kDa) in skeletal muscles (m. soleus, m. gastrocnemius), and titin in the left ventricular myocardium, as well as of the submembrane cytoskeletal protein dystrophin (427 kDa) in m. soleus and m. extensor digitorum longus (EDL), have been studied in the edible dormouse Glis glis during hibernation. The animals were divided into two experimental groups: “Summer activity” and “Hypothermia”. It was found that the development of atrophic changes in the skeletal muscles of hibernating animals is accompanied by a decrease in the dystrophin content. Specifically, the fluorescence intensity in skeletal muscle cross sections labeled with primary antibodies to dystrophin and Alexa Fluor® 488 conjugated secondary antibodies decreased in animals of the “Hypothermia” group by 2.7 times (p < 0.05) and 2.0 times (p < 0.05) in m. soleus and m. EDL, respectively. SDS electrophoresis of proteins in agarose-strengthened macroporous 2.2%-polyacrylamide gel revealed an insignificant decrease (by 15%, p ≤ 0.01) in the titin content compared to the myosin heavy chain content in m. gastrocnemius of animals of the “Hypothermia” group. The titin content in m. soleus and cardiac muscle, as well as the nebulin content in m. soleus and m. gastrocnemius, did not decrease during hibernation. These results are consistent with our previous data for other hibernators: long-tailed ground squirrel, brown and Himalayan black bears. It can be assumed that during evolution, hibernating animals developed the molecular mechanisms responsible for maintaining a stable level of giant sarcomeric cytoskeletal proteins during hibernation.