RESUMO
Objectives To understand the effect of intraperitoneal injection of naringenin,a SMAD3 inhibitor,on the skeletal muscle after acute contusion in a mouse model.Methods Seventy-two mice of 7-8 weeks old (20-24 g)were randomly divided into a control group,an acute contusion (B)group,an acute contusion+1％DMSO injection (C)group and an acute contusion+naringenin injection (D)group,each of 18.The acute contusion model was created by hitting the right tibialis anterior muscle in mice of all groups except the control group.Intraperitoneal injection of I％DMSO and naringenin were given to group C and D respectively every day until execution,while the 18 mice in the control group were fed without injury or injection.The time of injury was set as Day 0.After being fed for 28 days,all mice were executed and the right tibialis anterior was harvested.Western blotting was used to detect the difference of SMAD3,pSMAD3,Collagen Ⅰ,and α-SMA expression among the 3 groups.Hematoxylin-Eosin (HE)staining and Masson staining were used to detect the difference of pathological changes.Moreover,the appearance of fast twitch contraction and tetanic contraction were also documented to figure out the quality of the injured skeletal muscle.Results Compared with the control group,the SMAD3 and pSMAD3 level in injured skeletal muscle increased,but both were less in group D than group B and C.Similarly,the average level of Collagen Ⅰ and α-SMA in all three injury groups was higher than the control group,but the level of these indexes were lower in group D than that in group B and C.HE staining showed more mesenchyme in injury groups than the control group.Masson staining found the upregulation of fibrosis in injured muscles,with the area of fibrosis in group D significantly lower than group B and C.Compared with control,the injured skeletal muscle had significantly poorer fast twitch and tetanic contraction performance,with the condition of group D significantly better than group B and C.Conculsion The naringenin,a SMAD3 inhibitor,mitigates the phosphorylation of SMAD3 after acute contusion in a mouse model.The fibrosis and scar formation was alleviated,hence improving the healing of the injured skeletal muscles.