Flight training and dietary antioxidants have mixed effects on the oxidative status of multiple tissues in a female migratory songbird

AbstractBirds, like other vertebrates, rely on a robust antioxidant system to protect themselves against oxidative imbalance caused by energy-intensive activities such as flying. Such oxidative challenges may be especially acute for females during spring migration, since they must pay the oxidative costs of flight while preparing for reproduction; however, little previous work has examined how the antioxidant system of female spring migrants responds to dietary antioxidants and the oxidative challenges of regular flying. We fed two diets to female European starlings, one supplemented with a dietary antioxidant and one without, and then flew them daily in a windtunnel for two weeks during the fall and spring migration periods. We measured the activity of enzymatic antioxidants (GPx, SOD, CAT), non-enzymatic antioxidant capacity (ORAC), and markers of oxidative damage (protein carbonyls and lipid hydroperoxides) in four tissues: pectoralis, leg, liver, and heart. Dietary antioxidants affected enzymatic antioxidant activity and lipid damage in the heart, and non-enzymatic antioxidant capacity in the pectoralis and protein damage in leg muscle. In general, birds fed less antioxidants appear to incur increased oxidative damage while upregulating non-enzymatic and enzymatic antioxidant activity, though these effects were strongly tissue-specific. We also found a significant diet x training interaction for enzymatic antioxidant activity in the leg, and strong trends for diet x training interactions for enzymatic antioxidant activity in the heart and liver. Flight-training may condition the antioxidant system of females to dynamically respond to oxidative challenges, and females during spring migration may shift antioxidant allocation to reduce oxidative damage.【摘要】鸟类与其他脊椎动物一样，依赖一套完善的抗氧化系统，以抵御飞行等能量消耗巨大的活动所引发的氧化失衡。这类氧化应激对于春季迁徙的雌性鸟类而言可能尤为严峻，因为它们在为繁殖做准备的同时，还需承担飞行带来的氧化代价；然而此前鲜有研究探讨春季迁徙雌性鸟类的抗氧化系统如何响应膳食抗氧化剂与常规飞行带来的氧化应激。本研究为雌性欧洲椋鸟（European starlings）设置两种膳食方案：一组添加膳食抗氧化剂，另一组不添加；随后在秋季和春季迁徙期，让它们每日在风洞（windtunnel）中飞行，持续两周。本研究检测了4种组织（胸肌、腿部肌肉、肝脏与心脏）中的酶促抗氧化剂活性（enzymatic antioxidants，包括谷胱甘肽过氧化物酶（GPx）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT））、非酶促抗氧化能力（non-enzymatic antioxidant capacity, ORAC），以及氧化损伤标志物（蛋白质羰基（protein carbonyls）与脂质过氧化物（lipid hydroperoxides））。结果显示，膳食抗氧化剂会影响心脏中的酶促抗氧化剂活性与脂质损伤水平，以及胸肌中的非酶促抗氧化能力与腿部肌肉的蛋白质损伤水平。总体而言，摄入较少抗氧化剂的鸟类似乎会出现更严重的氧化损伤，同时会上调非酶促与酶促抗氧化活性，不过这些效应具有显著的组织特异性。本研究还发现，腿部的酶促抗氧化活性存在显著的膳食干预×飞行训练交互效应，而心脏与肝脏的酶促抗氧化活性则呈现出该交互效应的显著趋势。飞行训练或许可使雌性鸟类的抗氧化系统具备动态响应氧化应激的能力，而春季迁徙的雌性鸟类可能会调整抗氧化剂的分配，以减轻氧化损伤。