Expression of matrix metalloproteinases, inhibitor, and acid phosphatase in muscles of immobilized hindlimbs of rats.
External fixation procedures of limb immobilization provide excellent experimental models to study mechanisms involved in muscle disuse atrophy and recovery. Female Wistar rats (7-8 months old) had their right hindlimbs immobilized by an external fixation procedure for 5, 10, 21, and 30 days. Muscle mass of the gastrocnemius and quadriceps muscles was reduced by 41-46% in comparison with contralateral nonimmobilized legs. Acid phosphatase activities were significantly increased after 21 and 30 days of hindlimb immobilization. Histochemical staining for acid phosphatase activities increased in myofibers after the external fixation and also in macrophages in the adjacent extracellular matrix. Matrix metalloproteinase (MMP-2 and MMP-9) activities assessed by gel zymography and also a tissue inhibitor of metalloproteinases (TIMP-1) assessed by Western blot were elevated in the immobilized hindlimb muscles. Our study demonstrated that metalloproteinases are expressed relatively late after limb immobilization and appear to be responsible to a large degree for degradation of the extracellular matrix in experimental disuse atrophy.
Reznick
Abraham Z
AZ
Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, P.O. Box 9649, Haifa 31096, Israel. reznick@tx.technion.ac.il
Menashe
Ofir
O
Bar-Shai
Marina
M
Coleman
Raymond
R
Carmeli
Eli
E
D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D005260:Female; D019417:Hindlimb Suspension / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism*
D019715:Tissue Inhibitor of Metalloproteinase-1; D000135:Acid Phosphatase; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9