Bourguignon Aurore, Rameau Anaïs, Toullec Gaëlle, Romestaing Caroline, Roussel Damien
Université de Lyon, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023 CNRS, Université Claude Bernard Lyon 1, ENTPE, 69622 Villeurbanne cedex, France.
Université de Lyon, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023 CNRS, Université Claude Bernard Lyon 1, ENTPE, 69622 Villeurbanne cedex, France
J Exp Biol. 2017 Jul 1;220(Pt 13):2445-2451. doi: 10.1242/jeb.159087. Epub 2017 Apr 28.
In the final stage of fasting, skeletal muscle mass and protein content drastically decrease when the maintenance of efficient locomotor activity becomes crucial for animals to reactivate feeding behaviour and survive a very long period of starvation. As mitochondrial metabolism represents the main physiological link between the endogenous energy store and animal performance, the aim of this study was to determine how a very long, natural period of fasting affected skeletal muscle mitochondrial bioenergetics in king penguin () chicks. Rates of mitochondrial oxidative phosphorylation were measured in pectoralis permeabilized fibres and isolated mitochondria. Mitochondrial ATP synthesis efficiency and the activities of respiratory chain complexes were measured in mitochondria isolated from pectoralis muscle. Results from long-term (4-5 months) naturally fasted chicks were compared with those from short-term (10 day) fasted birds. The respiratory activities of muscle fibres and isolated mitochondria were reduced by 60% and 45%, respectively, on average in long-term fasted chicks compared with short-term fasted birds. Oxidative capacity and mitochondrial content of pectoralis muscle were lowered by long-term fasting. Bioenergetic analysis of pectoralis muscle also revealed that mitochondria were, on average, 25% more energy efficient in the final stage of fasting (4-5 months) than after 10 days of fasting (short-term fasted birds). These results suggest that the strong reduction in respiratory capacity of pectoralis muscle was partly alleviated by increased mitochondrial ATP synthesis efficiency. Such oxidative phosphorylation optimization can impact animal performance, e.g. the metabolic cost of locomotion or the foraging efficiency.
在禁食的最后阶段，当高效的运动活动对于动物重新启动觅食行为并在很长一段时间的饥饿中存活至关重要时，骨骼肌质量和蛋白质含量会急剧下降。由于线粒体代谢是内源性能量储备与动物表现之间的主要生理联系，本研究的目的是确定非常长的自然禁食期如何影响帝企鹅雏鸟骨骼肌线粒体生物能量学。在胸肌通透纤维和分离的线粒体中测量线粒体氧化磷酸化速率。在从胸肌分离的线粒体中测量线粒体ATP合成效率和呼吸链复合物的活性。将长期（4 - 5个月）自然禁食雏鸟的结果与短期（10天）禁食鸟类的结果进行比较。与短期禁食鸟类相比，长期禁食雏鸟的肌肉纤维和分离线粒体的呼吸活性平均分别降低了60%和45%。长期禁食会降低胸肌的氧化能力和线粒体含量。胸肌的生物能量分析还表明，在禁食最后阶段（4 - 5个月），线粒体的能量效率平均比禁食10天（短期禁食鸟类）后高25%。这些结果表明，胸肌呼吸能力的大幅下降部分通过提高线粒体ATP合成效率得到缓解。这种氧化磷酸化的优化会影响动物表现，例如运动的代谢成本或觅食效率。
