Abstract: Objective:To study the effects of exhaustive exercise and contusion on satellite cells activation and AXIN/GSK-3 β contents in ratskeletal muscle.Methods: 24 male SD rats (seven-week-old), were randomly divided into 4 groups with 6 in each group: control group (Control, C); immediately-after-exhaustive-exercise group (Exhaustive, E0); post-exhaustive exercise 24h group (E24); post-exhaustive exercise 48h group (E48). Another 18 SD rats were taken and randomly divided into 3 groups with 6 in each group: contusion immediate group (contusion, Do); post-contusion 24h group (D24); post-contusion 48h group (D48). All groups were killed respectively when at resting state and at different time points after exhaustive exercise and contusion respectively and the serum was extracted. The left quadriceps femoris was sampled and divided into two parts: one was used immediately for satellite cell culture experiment, and the other preserved in liquid nitrogen for measurement of AXIN and GSK-3β contents. The quadriceps femoris of another three neonatal rats were also takenfor satellite cell culture experiment. Results: (1) The results of culture in vitro showed that, by separating the rat muscle tissue of digestion, satellite cells with myogenic ability and high purity could be obtained in vitro. During the early stages of culture, a small amount of spindle satellite cells could be seen in the newborn rat the next day after culture, but the satellite cells of the other groups were growing slowly. On the third day and the fifth day, the spindle satellite cells of each group began to proliferate in quantity and reached the peaks. Then all the satellite cells had a good proliferation until 13th day after serial passage, and fusion and micro-tubuleswere observed in some of them. By comparing the results of each group, we concluded that the content of skeletal muscle satellite cell was lowest in control group,but highest in newborn rats. The proliferation rate was slowest in control group, but fastest in newborn rats.At the same time, the number and the proliferation rate of skeletal muscle satellite cells in contusion groups were significantly higher than that in the exhaustive exercise groups.(3) The results of Elisa showed that: The contents of AXIN, GSK-3β in skeletal muscle and serum of exhaustive groups and contusion groups, as compared with the control group, decreased significantly (P<0.01), but there was no significant difference between exhaustive groups(E0、E24、E48)and contusion groups(D0、D24、D48). Conclusions: (1) Exhaustive exercise and contusion can activate the skeletal muscle satellite cells and cause them to proliferate and differentiate. The number of skeletal muscle satellite cells activated in contusion groups was significantly larger than that in exhaustive groups. It may be caused by stronger stimulus of contusion. (3) The contents of AXIN, GSK-3β can be downregulated by exhaustive exercise and contusion, and may play an important role inactivating Wnt/beta-catenin signachannels and repairingskeletal muscle injury.

Key words: exhaustive exercise, contusion, satellite cells, Axial protein, glycogen synthase kinase-3β