Lipid-induced thermogenesis is up-regulated by the first cold-water immersions in juvenile penguins

Abstract : The passage from shore to marine life is a critical step in the development of juvenile penguins and is characterized by a fuel selection towards lipid oxida- tion concomitant to an enhancement of lipid-induced ther- mogenesis. However, mechanisms of such thermogenic improvement at fledging remain undefined. We used two different groups of pre-fledging king penguins (Apteno- dytes patagonicus) to investigate the specific contribution of cold exposure during water immersion to lipid metabo- lism. Terrestrial penguins that had never been immersed in cold water were compared with experimentally cold-water immersed juveniles. Experimentally immersed penguins underwent ten successive immersions at approximately 9–10 °C for 5 h over 3 weeks. We evaluated adaptive ther- mogenesis by measuring body temperature, metabolic rate and shivering activity in fully immersed penguins exposed to water temperatures ranging from 12 to 29 °C. Both never-immersed and experimentally immersed penguins were able to maintain their homeothermy in cold water, exhibiting similar thermogenic activity. In vivo, perfusion of lipid emulsion at thermoneutrality induced a twofold larger calorigenic response in experimentally immersed than in never-immersed birds. In vitro, the respiratory rates and the oxidative phosphorylation efficiency of isolated muscle mitochondria were not improved with cold-water immersions. The present study shows that acclimation to cold water only partially reproduced the fuel selection towards lipid oxidation that characterizes penguin acclima- tization to marine life.
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Article dans une revue
Journal of Comparative Physiology B, Springer Verlag, 2016, 186, pp.639-650. 〈10.1007/s00360-016-0975-3〉
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Soumis le : jeudi 16 juin 2016 - 15:15:45
Dernière modification le : jeudi 28 juin 2018 - 14:35:43

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Loïc Teulier, Benjamin Rey, Jérémy Tornos, Marion Le Coadic, Pierre-Axel Monternier, et al.. Lipid-induced thermogenesis is up-regulated by the first cold-water immersions in juvenile penguins. Journal of Comparative Physiology B, Springer Verlag, 2016, 186, pp.639-650. 〈10.1007/s00360-016-0975-3〉. 〈hal-01332835〉

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