Effects of RE-induced acute systemic hormonal concentration changes on local hormonal concentration and satellite cell content in trained individuals

Author(s)

Felipe Cassaro Vechin

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola de Educação Física e Esportes (EEFE/BT)
• Defense date: 2019-05-10

Examining board members

Carlos Ugrinowitsch; Patricia Chakur Brum; Cleiton Augusto Libardi; Renato Barroso da Silva

• Advisor: Carlos Ugrinowitsch

Abstract

Hormones such as testosterone, dehydroepiandrosterone (DHEA), cortisol and growth hormone (GH), as well as growth factors such as insulin-like growth factor (IGF-1) are acutely released into the blood after resistance exercise (RE). These hormones are related to the regulation of physiological processes in skeletal muscle cells. Recently, researchers have shown the presence of steroidogenic enzymes, responsible for metabolizing cholesterol in different steroid hormones, inside the muscle cell. This metabolization would enable muscle cells to regulate intramuscular hormone concentration. This intramuscular modulation may affect different physiological processes in these cells, such as satellite cell activity (SC). However, the role of acute RT-induced changes in serum hormone concentrations in regulating intracellular hormonal concentrations in muscle cells and, consequently, activity of SC is yet unknown in humans. To investigate this phenomenon, resistance-trained individuals underwent two different RE sessions to differently modulate serum hormonal responses. One session (HH) should significantly elevate serum concentrations of total and free testosterone, DHEA, cortisol, GH, and IGF-1, while the other session should not induce expressive elevations in these hormones (LH). Trained individuals were chosen because muscle cells are less impacted by RE as these individuals are more accustomed to RE. This design allows relating systemic and local hormonal modulation with possible modulations on SC activity. RE sessions were effective in acutely modulating the serum concentration of total testosterone, DHEA, GH, and cortisol. However, only cortisol was significantly raised for HH compared to LH. Consequently, only cortisol had its concentration differently modulated in muscle cells, being higher also after the HH session. The lack of elevations in muscle cell androgenic hormones was supported by the absence of changes in the steroidogenic enzymes gene expression such as 5α reductase and 17β Hydroxysteroid Dehydrogenase. Interestingly, myostatin and myogenin gene expression increased approximately nine and four times, respectively, 72 hours after the RE sessions. Finally, high cortisol levels in the muscle cell may have favored an expressive increase in myostatin gene expression, did not induce the expected changes in SC activity. This lack of modulation in the amount of SC and myionuclear content occurred regardless of the increase in myogenin expression, which could have favored the SC differentiation. Therefore, it is possible to suggest that when systemic hormones are expressively elevated like cortisol, there is a parallel increase in hormonal concentration in the muscle cell. The increase in muscle cell hormone concentration may have regulated the SC activity based as we did not observe the expected changes in the SC content after the RE sessions (AU)

• FAPESP's process: 15/19526-8 - Effects of acute systemic and local hormonal modulation on muscle satellite cells in well strength trained subjects.
• Grantee: Felipe Cassaro Vechin
• Support Opportunities: Scholarships in Brazil - Doctorate