Myotendinous junction adaptations to ladder-based resistance training: identification of a new telocyte niche

Author(s)

Neto, Jurandyr Pimentel ^[1] ; Rocha, Lara Caetano ^[1] ; Barbosa, Gabriela Klein ^[1] ; Jacob, Carolina dos Santos ^[1] ; Neto, Walter Krause ^[2] ; Watanabe, Ii-sei ^[3] ; Ciena, Adriano Polican ^[1]

Affiliation

^[1] Sao Paulo State Univ Julio de Mesquita Filho UNES, Inst Biosci IB, Lab Morphol & Phys Act LAMAF, Rio Claro, SP - Brazil

^[2] Sao Judas Tadeu Univ USJT, Dept Phys Educ, Lab Morphoquantitat Studies & Immunohistochem, Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Dept Anat, ICB 3, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 10, n. 1 AUG 24 2020.
• Web of Science Citations: 0

Abstract

The present study shows chronic adjustments in the myotendinous junction (MTJ) in response to different ladder-based resistance training (LRT) protocols. Thirty adult male Wistar rats were divided into groups: sedentary (S), calisthenics (LRT without additional load {[}C]), and resistance-trained (LRT with extra weight {[}R]). We demonstrated longer lengths of sarcoplasmatic invaginations in the trained groups; however, evaginations were seen mainly in group R. We showed a greater thickness of sarcoplasmatic invaginations in groups C and R, in addition to greater evaginations in R. We also observed thinner basal lamina in trained groups. The support collagen layer (SCL) adjacent to the MTJ and the diameters of the transverse fibrils were larger in R. We also discovered a niche of telocytes in the MTJ with electron micrographs of the plantar muscle and with immunostaining with CD34+in the gastrocnemius muscle near the blood vessels and pericytes. We concluded that the continuous adjustments in the MTJ ultrastructure were the result of tissue plasticity induced by LRT, which is causally related to muscle hypertrophy and, consequently, to the remodeling of the contact interface. Also, we reveal the existence of a collagen layer adjacent to MTJ and discover a new micro anatomic location of telocytes. (AU)

• FAPESP's process: 17/12525-1 - Plasticity at the myotendinous junction of adult rats subjected to stretching, associated with hypertrophy and swimming training: morphological, molecular and functional analyzes, with new perspectives about sarcomerogenesis
• Grantee: Adriano Polican Ciena
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/21977-3 - Adaptations to the lengths of the sarcomeres in the region of the myotendinous junction of the plantar muscle associated to physical exercise
• Grantee: Jurandyr Pimentel Neto
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 18/09199-8 - Adaptations in the myotendinous interface of wistar rats after resisted training - morphological, biochemical and functional analysis
• Grantee: Gustavo Crivelli
• Support Opportunities: Scholarships in Brazil - Scientific Initiation