Morphometric and Molecular Muscle Remodeling after Passive Stretching in Elderly Female Rats

• Published in: Clinics (São Paulo, Brazil) Vol. 75; p. e1769
• Main Authors: Martins, Hilana Rickli Fiuza, Zotz, Talita G. Gnoato, Messa, Sabrina Peviani, Capriglione, Luiz Guilherme A., Zotz, Rafael, Noronha, Lucia, Azevedo, Marina Louise Viola De, Gomes, Anna Raquel Silveira
• Format: Journal Article
• Language: English
• Published: Brazil Elsevier España, S.L.U 01.01.2020; Faculdade de Medicina / USP; Elsevier España
• Subjects: Aged; Aging; Animals; Collagen Type I - genetics; Collagen Type III - genetics; Extracellular Matrix; Female; Humans; MEDICINE, GENERAL & INTERNAL; Muscle Stretching Exercises; Muscle, Skeletal; Muscle-Stretching Exercise; Musculoskeletal System; Original; Rats; Rats, Wistar; Transforming Growth Factor beta1 - genetics; Rats; Aging; Muscle-Stretching Exercise; Musculoskeletal System; Extracellular Matrix
• ISSN: 1807-5932; 1980-5322; 1980-5322
• DOI: 10.6061/clinics/2020/e1769

To determine the effects of three sessions of a passive stretching exercise protocol on the muscles of elderly female rats. The effects of the stretching exercises on the soleus muscle were analyzed using immunohistochemistry [tissue inhibitors of matrix metalloproteinases (TIMP), the tumor necrosis factor-alpha (TNF-α), and the gene expression levels using real-time PCR of the transforming growth factor-beta 1 (TGF-β1), collagen type 1 (COL1), and collagen type 3 (COL3)]. Fifteen 26-month-old female Wistar rats were randomly divided into two groups, namely, Stretching (SG, n=8) and Control (CG, n=7). The passive mechanical stretching protocol consisted of a set of 4 1-minute repetitions, with 30 seconds between each repetition (total treatment of 4 minutes), three times a week for 1 week. Immunohistochemical analysis revealed an increase of 71.4% in the TNF-α (p=0.04) gene expression levels for the SG and a 58% decrease in the TGF-β1 gene expression levels (p=0.005) in the SG compared to that in the CG. No significant differences were observed between the groups for the immunostaining of TIMP-1 or the gene expression levels of COL1 and COL3. Three sessions of static stretching reduced the gene expression level of TGF-β1, which, owing to its anti-fibrotic role, might contribute to the remodeling of the intramuscular connective tissue of the aging muscle. In addition, immunostaining revealed that TNF-α levels increased in the aging muscle tissue in response to stretching, indicating its effect on stimulating extracellular matrix degradation. These outcomes have important clinical implications in reinforcing the use of stretching exercises in the elderly, considering that the aging muscle presents an infiltration of connective tissue.