
Fasting enhances mitochondrial efficiency in ducklings skeletal muscle by acting on the substrate oxidation system
Author(s) -
Damien Roussel,
Mélanie Boël,
Caroline Romestaing
Publication year - 2017
Publication title -
journal of experimental biology
Language(s) - English
Resource type - Journals
eISSN - 1477-9145
pISSN - 0022-0949
DOI - 10.1242/jeb.172213
Subject(s) - oxidative phosphorylation , mitochondrion , citrate synthase , respiratory chain , biology , uncoupling agents , coenzyme q – cytochrome c reductase , bioenergetics , biochemistry , skeletal muscle , medicine , cytochrome , respiration , electron transport chain , citric acid cycle , phosphorylation , endocrinology , microbiology and biotechnology , cytochrome c , metabolism , enzyme , anatomy
During food deprivation, animals must develop physiological responses to maximize energy conservation and survival. At the subcellular level, energy conservation is mainly achieved by a reduction in mitochondrial activity and an upregulation of oxidative phosphorylation efficiency. The aim of this study was to decipher mechanisms underlying the increased mitochondrial coupling efficiency reported in fasted birds. Mitochondrial oxidative phosphorylation activity, efficiency and membrane potential were measured in mitochondria isolated from gastrocnemius muscle of ducklings. The content and activities of respiratory chain complexes were also determined. Results from 6 days fasted ducklings were compared with ad libitum fed ducklings. Here, we report that 6 days of fasting improved coupling efficiency in muscle mitochondria of ducklings by depressing proton-motive force through the down-regulation of substrate oxidation reactions. Fasting did not change the basal proton conductance of mitochondria, but largely decreased the oxidative phosphorylation activity, which was associated with a decreased activities of succinate-cytochrome c reductase (complexes II-III) and citrate synthase, and altered contents in cytochromes b and c+c1. In contrast, fasting did not change cytochrome aa3 content or complexes I, II and IV activities. Altogether, these data show that the lower capacity of the respiratory machinery to pump protons in 6 days fasted ducklings generates a lower membrane potential, which triggers a decreased proton leak activity and thus a higher coupling efficiency. We propose that the main site of action would be located at the level of coenzyme Q pool/complex III of the electron transport chain.