Sequential effects of eccentric exercise on the skeletal muscle cell proliferation and vimentin expression in rats

Weihong SONG; Xiaowen LIANG; Yanping LIAO; Changfa TANG

ABSTRACT

BACKGROUND:

The regeneration and repair of skeletal muscle after injury relies on the new nucleus formed through muscle satellite cell proliferation. However, there are few reports on the relationship between the skeletal muscle cell proliferation and the vimentin expression.

OBJECTIVE:

To explore the relationship between the skeletal muscle cell proliferation and the vimentin expression, as well as the mechanism underlying the repair of exercise-induced skeletal muscle micro-injury. DESIGN, TIME AND

SETTING:

A randomized controlled animal experiment was done at the Sports Human Science Experimental Center in Hunan Normal University between December 2007 and September 2008. MATERIALS A total of 50 male SD rats, aged 8 weeks, were randomly divided into a control group and a training group which were subdivided in to four groups at the time points of immediate post-exercise, hour 3, hour 24 and hour 48 post-exercise, with 10 ones in each of the five groups.

METHODS:

Rats in the training group underwent 3 days of repetitive exhausting eccentric exercise on a treadmill of-16° slope at the speed of 16 m/min. Rats in the control group underwent no running. MAIN OUTCOME

MEASURES:

Rats in the training group was taken for measurement immediate, 3 hours, 24 hours and 48 hours post-exercise respectively. Immunohistochemistry was adopted to determine the proliferating coil nuclear antigen (PCNA) A expression and the vimentin expression in medial head of triceps brachii muscle cells in each group at different phases of repair.

RESULTS:

The skeletal muscle cell showed sequentially-changed proliferation. The proliferation index of the training group was significantly higher than that of the control group immediately post-exercise. At hour 24 post-exercise, it reached the peak. Hour 48 post-exercise saw the decreased proliferation. The expression of vimentin also exhibits a sequential change after exercise. Moreover, its immunoreaction score changed with time in the same direction with the proliferation index, but there is no correlation between the two.

CONCLUSION:

Three days of repeated exhausting eccentric exercise can induce the sequential changes of skeletal muscle cell proliferation and vimentin expressions. Vimentin expression has some kinds of correlations with skeletal muscle cell proliferation, but it is not the only factor that matters.