STRUCTURAL AND FUNCTIONAL ANALYSIS OF MUSCLES DIAPHRAGM OF WISTAR RATS AFTER ADMINISTRATION OF TESTOSTERONE PROPIONATE.

• Grant number: 24/14001-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2024
• End date: November 30, 2025
• Field of knowledge: Biological Sciences - Morphology - Histology
• Principal Investigator: Diogo Correa Maldonado
• Grantee: Mário Jorge Cruz e Silva
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated research grant: 22/16408-8 - Effects of pre-resistance training testosterone propionate sensitization on signal pathways for protein synthesis and morphology of triceps surae and plantaris muscles of Wistar rats, AP.R

Abstract

Patients recommended for lung transplantation suffer from sarcopenia and cachexia and these factors have an impact on quality of life after transplantation. In this way, the main respiratory muscle of the human body, the m. diaphragm, considered fundamental for respiratory mechanics, has structural and that negatively impact respiratory dynamics. It is known that testosterone promotes muscle hypertrophy and can restore muscle function in a short period of time. Therefore, this scientific initiation project aims to analyze the behavior of muscle fibers in the respiratory system of Wistar rats when using testosterone propionate, in order to analyze the possible effects on this muscle group. The material and methods to be used will be 63 male Wistar rats subjected to the administration of testosterone propionate for two, four and 12 weeks. After the administration period, the animals will be euthanized, the diaphragm muscle will be collected, as well as the blood for hormonal analysis. The number of myonuclei per fiber, thus the myonuclear domain and myonuclei morphology will be analyzed with specific antibodies using the immunoflurescence technique. The cross-sectional area will also be evaluated. Maximum loaded load tests will be conducted at the beginning of the experiment and 48h before euthanasia. For statistical analysis, mean ± standard deviation will be adopted and frequency (%) will be used for categorical variables. The independent GLM test and for measuresrepeated tests will be used, followed by the Post-hoc Tukey test and Etan square effect size (·2) with Post-hoc Cohen'd. Significance will be accepted when p <0.05. It is expected that the administration of testosterone propionate increases myonuclear content in proportion to the increase in cross-sectional area, in addition to increasing strength when comparing groups with and without testosterone. It is also expected that groups that previously use testosterone for 2 and 4 weeks will maintain part of the acquired myonuclear content