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 cytoskeletalproteins titin (3000–3700 kDa) and nebulin (770 kDa) in skeletalmuscles (m. soleus, m. gastrocnemius), and titin in theleft ventricular myocardium, as well as of the submembrane cytoskeletalprotein dystrophin (427 kDa) in m. soleus and m. extensor digitorum longus (EDL), have been studied in the edibledormouse Glis glis during hibernation.The animals were divided into two experimental groups: “Summer activity”and “Hypothermia”. It was found that the development of atrophicchanges in the skeletal muscles of hibernating animals is accompaniedby a decrease in the dystrophin content. Specifically, the fluorescenceintensity in skeletal muscle cross sections labeled with primary antibodiesto dystrophin and Alexa Fluor® 488 conjugatedsecondary antibodies decreased in animals of the “Hypothermia” groupby 2.7 times (p < 0.05)and 2.0 times (p < 0.05)in m. soleus and m. EDL, respectively. SDS electrophoresisof proteins in agarose-strengthened macroporous 2.2%-polyacrylamidegel revealed an insignificant decrease (by 15%, p ≤ 0.01) in the titin content comparedto the myosin heavy chain content in m.gastrocnemius of animals of the “Hypothermia” group.The titin content in m. soleus andcardiac muscle, as well as the nebulin content in m. soleus and m.gastrocnemius, did not decrease during hibernation. Theseresults are consistent with our previous data for other hibernators:long-tailed ground squirrel, brown and Himalayan black bears. Itcan be assumed that during evolution, hibernating animals developedthe molecular mechanisms responsible for maintaining a stable levelof giant sarcomeric cytoskeletal proteins during hibernation.