Dr. Fernanda Silva Carneiro

Conference 2024 Live Talk

Talk Title

Evaluation of skeletal muscle mitochondrial respiratory capacity in response to a high-fat diet over time

Authors and Affiliations

Fernanda Silva Carneiro1, Matheus Biscaro Rocha1, Scylas José de Andrade Junior1, Carlos Kiyoshi Katashima1, Eduardo Rochete Ropelle1.

1. Laboratory of Molecular Biology of Exercise, State University of Campinas, Limeira, Sao Paulo, Brazil.

Abstract

Background

Background: Obesity is a chronic and metabolic disease caused by a disbalance between energy expenditure and consumption, which can lead to weight gain, increased adiposity, and related pathologies. In muscular tissue, obesity can increase the risk of muscle loss and sarcopenia, where mitochondria play a key role in the maintenance of energy homeostasis to prevent muscular dysfunction, showing morphological, functional and metabolic alterations due to the stress promoted by obesity, leading to a increase of reactive oxygen species (ROS) production, mitophagy and affecting the electron transport chain (ETC) function. Due to the capacity of a high-fat diet to modulate ETC, we hypothesized that a high-fat diet promotes different changes in the phosphorylation chain and mitochondrial respiratory capacity in mice over time during the establishment of obesity.

Methods

Methods: The experiments were performed in 8 weeks-old C57BL/6J male mice fed ad libitum with a standard chow diet (Ctrl), a 45% high-fat diet during 3 days (acute HFD), 8 weeks (chronic HFD) or 52 weeks (old HFD) (N=6 per group, Ethics protocol 6005-1/22). After the fed protocol, the animals were anesthetized and euthanized, and the gastrocnemius tissue was e permeabilizated. Subsequently, 2mg of dry-fibers of muscle respiration were analyzed using the equipment Oroboros O2k using the following substrates and inhibitors: glutamate (0.4M) and malate (2M), ADP (0.5M), succinate (1M), oligomycin (5mM), FCCP (1mM), and rotenone (1mM) with antimycin (5mM). The statistical analysis used was ANOVA one-way (p<0.05 for significance). Results Results: It was observed a decrease of respiratory capacity in the ETC complexes I, II and V after 3 days of HFD diet (p<0.0001) and a increase of respiration in aged mice (p<0.001), with a persistent reduced respiration in chronic and aged-high-fat mice in complex II during 8 and 52 weeks of diet (p<0.0001), with a reduced respiratory chain ratio (RCR) in aged mice. Conclusions Conclusions: These results strongly suggest that obesity alters the mitochondrial respiratory capacity from the 3 days of high-fat diet, with a persevering dysfunction of complex II.