[Sphingolipids in skeletal muscles of C57B1/6 mice after short-term simulated microgravity]

For the first time in skeletal muscle, the sphingolipid profile and key enzymes involved in the generation of ceramide in cells were investigated in simulated microgravity. It was found that, in C57B1/6 mice, the 4-day hindlimb unloading, in addition to reducing the mass of m. soleus, leads to the ceramide accumulation (3-fold) and the decrease of sphingomyelin content in this muscle (7.2-fold), as well as to the increase (2.7-fold) of protein level of acid sphingomyelinase. In a loaded m. biceps brachii the amount of ceramide is also enhanced, but both the amount of sphingomyelin and sphingomyelinase, as well as the muscle mass do not change, while the level of serine palmitoyltranspherase becomes significantly lower than in control mice. Taking into account the negative effects of ceramide in skeletal muscle (insulin resistance, inhibition of protein synthesis and increase of its decay) we can assume that sphingolipid mechanisms may be involved in the development of structural and functional abnormalities of skeletal muscle under conditions of weightlessness.