Immobilization and therapeutic passive stretching generate thickening and increase the expression of laminin and dystrophin in skeletal muscle

Abstract

Extracellular matrix and costamere proteins transmit the concentric, isometric, and eccentric forces produced by active muscle contraction. The expression of these proteins after application of passive tension stimuli to muscle remains unknown. This study investigated the expression of laminin and dystrophin in the soleus muscle of rats immobilized with the right ankle in plantar flexion for 10 days and subsequent remobilization, either by isolated free movement in a cage or associated with passive stretching for up to 10 days. The intensity of the macrophage response was also evaluated. One hundred and twenty-eight female Wistar rats were divided into 8 groups: free for 10 days; immobilized for 10 days; immobilized/free for 1, 3, or 10 days; or immobilized/stretched/free for 1, 3, or 10 days. After the experimental procedures, muscle tissue was processed for immunofluorescence (dystrophin/laminin/CD68) and Western blot analysis (dystrophin/laminin). Immobilization increased the expression of dystrophin and laminin but did not alter the number of macrophages in the muscle. In the stretched muscle groups, there was an increase in dystrophin and the number of macrophages after 3 days compared with the other groups; dystrophin showed a discontinuous labeling pattern, and laminin was found in the intracellular space. The amount of laminin was increased in the muscles treated by immobilization followed by free movement for 10 days. In the initial stages of postimmobilization (1 and 3 days), an exacerbated macrophage response and an increase of dystrophin suggested that the therapeutic stretching technique induced additional stress in the muscle fibers and costameres.

Effects of Chronic Stretching on Soleus Muscle of Wistar Female Rats

“…Studies with young male rats showed that stretching exercise induced structural changes that increased muscle volume, muscle fiber cross-sectional area, and serial sarcomere number (Coutinho et al, 2004;Cação-Benedini et al, 2014). Ywazaki et al (2016) using an aged rat model verified an increase in muscle fiber cross-sectional area and sarcomerogenesis after a six-week chronic stretching protocol.…”

Effects of Ultrasound and Stretching on Skeletal Muscle Contusion in Rats: Immunohistochemistry Analysis

“…Rantanen et al reported that pulsed ultrasound improved the development of myogenic precursor cells, myogenic cells, and fibrillar collagen in injured muscle. However, optimal repair of striated muscle requires not only an interaction between regenerating muscle cells and the extracellular matrix, but also the neovascularization and adhesion of the myofibers to the extracellular matrix, indicating the importance of proteins involved in this mechanism such as desmin and laminins (Wilkin et al, 2004;Piedade et al;Rantanen et al;Shu et al;Cação-Benedini et al, 2014;Gianello et al, 2016).…”

“…An increase in sarcomerogenesis and an antifibrotic effect after a stretching protocol of injured rat gastrocnemius has been reported (de Macedo et al, 2014(de Macedo et al, , 2016. Although the proteins desmin and laminin involved in the sarcomerogenesis and muscle healing, have not yet been investigated (Yu & Thornell, 2002;Cação-Benedini et al;Gianelo et al, 2016).…”

Regulation of extracellular matrix elements and sarcomerogenesis in response to different periods of passive stretching in the soleus muscle of rats

“…As such, differences in the stretching methods applied (continuous vs. intermittent) affect the muscle growth 6 and viscoelastic properties of tendon structures 15 . In addition, immobilization approaches 16 – 18 and stretching techniques have been investigated in denervated rat muscle 19 . However, there is limited evidence regarding the effect of different periods of stretching on ECM homeostasis.…”