How physical exercise changes rat myotendinous junctions: an ultrastructural study

  • D. Curzi Urbino University "Carlo Bò", Italy.
  • S. Salucci Urbino University "Carlo Bò", Italy.
  • M. Marini University of Bologna, Italy.
  • F. Esposito University of Milan, Italy.
  • L. Agnello Don Gnocchi Foundation, Milan, Italy.
  • A. Veicsteinas Don Gnocchi Foundation, Milan, Italy.
  • S. Burattini Urbino University "Carlo Bò", Italy.
  • E. Falcieri | elisabetta.falcieri@uniurb.it Urbino University "Carlo Bò" and Rizzoli Orthopaedic Institute, Bologna, Italy.

Abstract

Myotendinous junctions can be easily injured by overloading or trauma, and exercise training may be a way of increasing their resistance to mechanical stress. To this end, we examined herein the morphological changes induced by moderate exercise training in the myotendinous junctions of extensor digitorum longus and gastrocnemius muscles in rats. Twelve Sprague-Dawley rats were used in this investigation. Six of them were trained to run on a treadmill for 1 h/day, 3 days/week over 10 weeks in order for them to achieve a running rate of 25 m/min at the end of the training period. Six age-matched sedentary rats were used as controls. The rats were sacrificed 24 h after the final training session, and the extensor digitorum longum (EDL) and the gastrocnemium were excised; the myotendinous junctions (MTJ) were then prepared and observed with electron microscopy. Digitation branching was evaluated by counting the bifurcations in the MTJ protrusions. Our observations indicate that exercise does indeed induce changes in MTJ morphology. In both muscles the number of bifurcated interdigitations increased significantly, as well as, in gastrocnemius, the branching of the finger-like processes. It was demonstrated that the MTJ is able to adapt to an increase in tensile force by enlarging the muscle-tendon contact area and, consequently, mechanical resistance.

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Author Biographies

S. Salucci, Urbino University "Carlo Bò"
DiSTeVA
M. Marini, University of Bologna
Department of Histology, Embryology and Applied Biology
F. Esposito, University of Milan
Department of Sport, Nutrition and Health Sciences
L. Agnello, Don Gnocchi Foundation, Milan
Center of Sport Medicine
A. Veicsteinas, Don Gnocchi Foundation, Milan
Center of Sport Medicine
S. Burattini, Urbino University "Carlo Bò"
DiSTeVA
Published
2012-04-16
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Original Papers
Supporting Agencies
The work was supported by Urbino University and the Ministry of Education, University and Research (PRIN 2009).
Keywords:
Myotendinous junctions, ultrastructure, tension, training, exercise, skeletal muscle, tendon.
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How to Cite
Curzi, D., Salucci, S., Marini, M., Esposito, F., Agnello, L., Veicsteinas, A., Burattini, S., & Falcieri, E. (2012). How physical exercise changes rat myotendinous junctions: an ultrastructural study. European Journal of Histochemistry, 56(2), e19. https://doi.org/10.4081/ejh.2012.19