Growth hormone plus resistance exercise attenuate structural changes in rat myotendinous junctions resulting from chronic unloading

  • D. Curzi Carlo Bo University of Urbino, Italy.
  • D. Lattanzi Carlo Bo University of Urbino, Italy.
  • S. Ciuffoli Carlo Bo University of Urbino, Italy.
  • S. Burattini Carlo Bo University of Urbino, Italy.
  • R.E. Grindeland NASA - Ames Research Center, United States.
  • V.R. Edgerton University of California, United States.
  • R.R. Roy University of California, United States.
  • J.G. Tidball University of California, United States.
  • E. Falcieri | elisabetta.falcieri@uniurb.it Carlo Bo University of Urbino CNR, Italy.

Abstract

Myotendinous junctions (MTJs) are specialized sites on the muscle surface where forces generated by myofibrils are transmitted across the sarcolemma to the extracellular matrix. At the ultrastructural level, the interface between the sarcolemma and extracellular matrix is highly folded and interdigitated at these junctions. In this study, the effect of exercise and growth hormone (GH) treatments on the changes in MTJ structure that occur during muscle unloading, has been analyzed. Twenty hypophysectomized rats were assigned randomly to one of five groups: ambulatory control, hindlimb unloaded, hindlimb unloaded plus exercise (3 daily bouts of 10 climbs up a ladder with 50% body wt attached to the tail), hindlimb unloaded plus GH (2 daily injections of 1 mg/kg body wt, i.p.), and hindlimb unloaded plus exercise plus GH. MTJs of the plantaris muscle were analyzed by electron microscopy and the contact between muscle and tendon was evaluated using an IL/B ratio, where B is the base and IL is the interface length of MTJ’s digit-like processes. After 10 days of unloading, the mean IL/B ratio was significantly lower in unloaded (3.92), unloaded plus exercise (4.18), and unloaded plus GH (5.25) groups than in the ambulatory control (6.39) group. On the opposite, the mean IL/B ratio in the group treated with both exercise and GH (7.3) was similar to control. These findings indicate that the interaction between exercise and GH treatments attenuates the changes in MTJ structure that result from chronic unloading and thus can be used as a countermeasure to these adaptations.

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Author Biographies

D. Curzi, Carlo Bo University of Urbino
Dept. of Earth, Life and Environmental Science
D. Lattanzi, Carlo Bo University of Urbino
Dept. of Earth, Life and Environmental Science
S. Ciuffoli, Carlo Bo University of Urbino
Dept. of Earth, Life and Environmental Science
S. Burattini, Carlo Bo University of Urbino
Dept. of Earth, Life and Environmental Science
R.E. Grindeland, NASA - Ames Research Center
Life Sciences Division
V.R. Edgerton, University of California

Department of Integrative Biology and Physiology and the Brain Research Inst.

Department of Neurology and Neurosurgery

R.R. Roy, University of California
Department of Integrative Biology and Physiology and the Brain Research Inst.
J.G. Tidball, University of California
Molecular, Cellular & Integrative Physiology Program
E. Falcieri, Carlo Bo University of Urbino CNR

Dept. of Earth, Life and Environmental Sciences

Molecular Genetics Institute and Rizzoli Orthopaedic Institute

Published
2013-11-13
Info
Issue
Section
Original Papers
Supporting Agencies
The research was supported by Urbino University and the Ministry of Education, University and Research (PRIN 2009).
Keywords:
Myotendinous junction, ultrastructure, exercise, growth hormone, atrophy, disuse, unloading.
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How to Cite
Curzi, D., Lattanzi, D., Ciuffoli, S., Burattini, S., Grindeland, R., Edgerton, V., Roy, R., Tidball, J., & Falcieri, E. (2013). Growth hormone plus resistance exercise attenuate structural changes in rat myotendinous junctions resulting from chronic unloading. European Journal of Histochemistry, 57(4), e37. https://doi.org/10.4081/ejh.2013.e37