Construction and evaluation of a rat model with blunt contusion of skeletal muscle

Hao WANG; Hai-Chao LIU; Shaoqing CHEN

ABSTRACT

Objective:

To establish a reliable,stable and clinically realistic model of blunt contusion injury to the rat skele-tal muscle.

Method:

A model of the rat gastrocnemius muscle blunt contusion injury was established by using a weight of 170g,a height of 70cm and a spring with a diameter of 0.5cm at the bottom to buffer the polymeric strik-ing part and guide the fall to hit for 5 consecutive times.The gait changes of rats were evaluated by CatWalk analysis system at 0h,12h,24h,3 days,7 days and 14 days after modeling;local histopathological changes were observed by HE staining and local ultrastructural changes were observed by transmission electron micros-copy.Enzyme-linked immunosorbent assay(ELISA)was used to detect the changes of tumor necrosis factor-α(TNF-α)in local tissues.

Result:

Compared with the blank group,the mean speed and maximum speed change rate of the model group were significantly decreased,and the difference was statistically significant(P＜0.001);compared with the normal foot group,the maximum contact area,footprint area and standing phase duration of the limb of the injured limb group were significantly decreased,and the difference was statistically significant(P＜0.05).A large infiltration of inflammatory cells and massive lysis necrosis of muscle fibers were observed on HE stain-ing after 3 days.By 14 days,although scar tissue was still present,tissue repair with HE staining was almost indistinguishable from that of the blank group.Vacuolation was observed in part of the sarcoplasmic reticulum at 0h after the blow,and lysis of muscle fibers and part of the sarcoplasmic reticulum at 3 days with in-creased inflammatory response which basically returned to normal by 14 days.The TNF-α level began to rise gradually and reached a peak from 0h to 12h after injury,and remained higher level from 12h to 72h,and the difference was statistically significant compared with the blank group(P＜0.05),and basically returned to the normal level by 14 days.

Conclusion:

The model can cause moderate damage of skeletal muscle in rats,with a 14-day natural recovery time at least.It can provide as one of the methods for for the establishment of the rat skeletal muscle blunt contusion model.