Electrical stimulation increases matrix metalloproteinase-2 gene expression but does not change its activity in denervated rat muscle

• Published in: Muscle & nerve 2008-05, Vol.37 (5), p.593-600
• Main Authors: Russo, Thiago Luiz, Peviani, Sabrina Messa, Durigan, João Luiz Quagliotti, Salvini, Tania Fátima
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; connective tissue; Diseases of striated muscles. Neuromuscular diseases; Dose-Response Relationship, Radiation; Electric Stimulation; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic - radiation effects; Male; Matrix Metalloproteinase 2 - genetics; Matrix Metalloproteinase 2 - metabolism; Medical sciences; muscle atrophy; Muscle Denervation; Muscle Fibers, Skeletal - metabolism; Muscle Fibers, Skeletal - radiation effects; Muscle, Skeletal - innervation; Muscle, Skeletal - radiation effects; nerve injury; Neurology; Rats; Rats, Wistar; skeletal muscle; Striated muscle. Tendons; Time Factors; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.20985

Muscle‐fiber atrophy occurs concomitantly with intramuscular connective tissue proliferation following denervation. These events contribute to the impairment of mechanical and functional properties of denervated muscles and compromise their recovery. Electrical stimulation (ES) is used in human rehabilitation to treat denervated muscles. However, the effects of this therapy on the intramuscular extracellular matrix (ECM) remain uncertain. Metalloproteinases (MMPs) are responsible by remodeling ECM in many neuromuscular disorders. This study evaluates the effect of ES on the activity of two important MMPs, MMP‐2 and MMP‐9, both involved in ECM remodeling of rat denervated muscles. Thirty‐four Wistar rats (3 months old, 356 ± 38.7 g) were divided into five groups: denervated (D); D+ES; sham denervation; normal (N); and N+ES. Twenty maximal muscle contractions were stimulated every 48 h using surface electrodes, as generally used in the rehabilitation of human denervated muscle. Both zymographic analysis and real‐time polymerase chain reaction (PCR) of MMPs were used to evaluate muscle after denervation for 28 days. Both the D and D+ES groups showed increased MMP‐2 activity compared with the N group (P < 0.05). Furthermore, only the D+ES had increased MMP‐2 gene expression compared with the N group (P < 0.05). MMP‐9 activity was not detected in any of the groups. The results of this study indicate that denervation increases MMP‐2 activity, and ES regulates MMP‐2 gene expression in rat denervated skeletal muscle. These findings clarify the effects of ES on the ECM of denervated muscle and may be helpful in designing new therapeutic strategies for rehabilitation in patients with denervation of muscle. Muscle Nerve, 2008