Реферат: Under conditions of microgravity or simulated gravitational unloading, the skeletal muscles of mammals undergo a number of negative changes. They include mitochondrial biogenesis decline, slow-to-fast fiber-type shift, increase of proteolysis and decrease in protein synthesis, which in turn lead to muscle atrophy and weakness. Electrical muscle stimulation technique can directly restore the activity of slow or fast muscle fibers depending on the frequency of stimulation (50-60 Hz for fast fibers and 10 Hz for slow fibers). High-frequency electrical stimulation of skeletal muscles is used in sports medicine and leads to increased muscle hypertrophy in athletes; it is often used in addition to training or as a replacement for training for athletes who are forced for some reason to stop training. Low-frequency electrical stimulation of rodent muscles leads to an increase in the content of mitochondrial enzymes and the proportion of “slow” muscle fibers, and also leads to a decrease in muscle fatigue in humans (Scott, Vrbova et al. 1985). The goal of the ongoing project was to study the effect of electrical stimulation on a number of molecular changes recorded after functional unloading (using the “dry immersion” model), and to compare the results obtained after “dry” immersion with electrical stimulation and after “dry” immersion without preventive measures. 6-day dry immersion (DI) did not lead to any significant changes in soleus muscle myofiber cross-sectional area, while after the DI with electrical stimulation (ES-DI) fast-type soleus myofibers CSA were significantly lower than before the ES-DI (Figure 1). The lack of effect of 6-day DI on slow myofiber CSA is in variance with the previous results in a 7-day DI experiments, where slow-type fibers CSA was downregulated (Moukhina, Shenkman et al. 2004). The causes of this discrepancy remain obscure. The level of m-TOR target p-p70 did not change after the DI, and another mTOR target, p-4E-BP was declined (Figure2). ES during DI resulted in upregulation of p-p70 vs pre-DI samples and no changes in p-E-BP content. At the same time, 6-day DI lead to significant downregulation of mitochondrial-related markers genes expression vs pre-DI samples, such as COXI,, COXIV, MTRNR1 andMTRNR2 (Figure 2 A-E), while after the ES-DI these parameters did not change vs pre-ES-DI values (Figure 3A-E). However, PGC1alpha dene expression declined in the post-DI samples vs pre-DI in the both experiments (Figure 2-3, A). It also should be mentioned, that gene expression of several mitophagy regulators genes expression (such as BNIP3, LC3B, Fundc, OPTN) were either downregulated or did not change after the DI, while being significantly upregulated after the ES-DI (Figure 4,5). This situation may indicate the autophagy and/or mitophagy upregulation in the ES-DI sample group, which may explain the downregulation of fast-type fibers CSA in the ES-DI sample group.

Библиографическая ссылка: Sharlo К. , Vilchinskaya N. , Shishkin N. , Ponomarev I. , Tyganov S. , Shenkman B.
Effects of Muscle Electrical Stimulation under 6-day Dry Immersion on Soleus Muscle Signaling
В сборнике 43rd Annual International Gravitational Meeting. 26-31 May. 2024. Dubai, United Arab Emirates. 2024.

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