Effects of acute systemic and local hormonal modulation on muscle satellite cells in well strength trained subjects.

• Grant number: 17/18069-8
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: December 01, 2017
• End date: November 11, 2018
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Carlos Ugrinowitsch
• Grantee: Felipe Cassaro Vechin
• Supervisor: Jakob Vingren
• Host Institution: Escola de Educação Física e Esporte (EEFE). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University of North Texas, United States
• Associated to the scholarship: 15/19526-8 - Effects of acute systemic and local hormonal modulation on muscle satellite cells in well strength trained subjects., BP.DR

Abstract

Resistance training (RT) is one of the most effective strategies to increase muscle strength and mass. However, highly trained individuals usually present lower strength and muscle mass gains than untrained counter-parts. Among the mechanisms proposed to explain the decreases in muscle mass accretion (muscle hypertrophy), the theory of myonuclear domain has gained importance in the literature. This theory postulates that each myonucleus within the muscle cell is responsible for organizing a limited cytoplasm volume. Thus, as the muscle cell grows, the existing myonuclei can increase their transcription capacity (e.g. protein synthesis) up to a limited point, reaching a ceiling effect. Researchers have suggested that the only option to overcome this ceiling effect is to add myonuclei to muscle cells. To add myonuclei to the muscle cells, a group of quiescent cells capable of undergoing cell division, satellite cells, need to be activated, differentiated, and fused to existing muscle cells. Once fused, these cells donate their myonyclei to muscle cells increasing their ability to synthesize protein. Among the factors responsible for activating and differentiating satellite cells are anabolic hormones and growth factors such as testosterone, growth hormone and mechanical growth factor (MGF). As a result, systemic hormonal response should have a predominant role in the muscle hypertrophy in trained subjects, in which, existing myonucleus reached their maximum capacity of protein synthesis. Possibly, systemic hormonal response through modulation of local hormones and MGF stimulate the activation, proliferation, and differentiation of satellite cells Accordingly, the objective of this study is to investigate whether acute systemic hormonal response affects local levels of these hormones and growth factors with consequent effect in the regulation of muscle satellite cells in individuals trained in strength.