急性和慢性刺激条件下树麻雀的糖脂代谢和抗氧化适应机制研究

Stress is the physiological and behavioral adaptive responses of the organism during exposure to environmental stimuli, which is critically important for promoting individual survival. The regulatory mechanisms between acute stress and chronic stress differ significantly although both of them leading to increase in glucocorticoids induce imbalances of energy metabolism and redox homeostasis. In vertebrates, birds are featured with higher metabolic rate and stronger antioxidant capacity, whereas the regulatory mechanism of these features in response to stress response remains largely unknown. In the present proposal, based on our previous findings on stress response in birds, we aim to determine the changes in the plasma corticosterone and metabolites, the metabolic enzymes related glucose and lipids, oxidative stress and antioxidant parameters, and key functional genes and proteins in the liver of Eurasian tree sparrows (Passer montanus) in response to capture-restraint stress and captivity stress using comparative physiology and “Omics” techniques. Furthermore, the key functional genes, metabolites in the energy metabolism and antioxidant system will be identified to illustrate their regulatory mechanism in free-living birds in response to both acute and chronic stress. Our results may contribute to uncovering the physiological strategy and underlying molecular regulatory mechanism in animals transferred from free-living to captivity status, and can be applied in formulating rational strategies for artificial acclimation and ex situ conservation in free-living animals as well.

应激是机体对外界刺激产生的适应性生理和行为反应，对维持自身生存至关重要。急性和慢性应激均可引起机体糖皮质激素升高，导致能量代谢和氧化还原平衡改变，但机制不同。脊椎动物中，鸟类具有高代谢率和强抗氧化能力，然而这些特征在应激状态的响应机制尚不明确。本项目基于前期成果，利用比较生理学和组学技术，探讨树麻雀在急性和慢性应激过程中血浆皮质酮及糖脂代谢物，肝脏代谢酶、氧化应激和抗氧化指标、关键基因及蛋白的变化特征，并筛选能量代谢和抗氧化通路中的相关基因、效应物和产物，阐述鸟类在应激过程中糖脂代谢和抗氧化适应的调节机制。研究结果对揭示动物从野生到笼养状态的生理适应策略及分子机理具有重要意义，对制定动物的人工驯化和易地保护策略具有应用价值。

脊椎动物中，鸟类具有高代谢率和强抗氧化能力，然而这些特征在应激状态的响应机制尚不明确。本项目利用比较生理学和组学技术研究小型鸟类——树麻雀（Passer montanus）在经历急性捕获抑制刺激（捕获3min内为本底，30min和60min为急性应激状态）和慢性笼养刺激（笼养1d、7d、15d和30d）过程中身体状况、血浆皮质酮，血浆、肝脏、大脑、心脏和胸肌内能量代谢物和代谢酶，肝脏氧化应激反应、氧化损伤和抗氧化指标的变化特征，并利用代谢组学和转录组学技术筛选了糖脂代谢和抗氧化通路中关键基因和代谢物。主要结果和结论有：(1) 树麻雀的身体状况在急性和慢性应激条件下均显著下降、血浆皮质酮均显著升高，这个过程是机体表现“应激介导”的生理变化特征；(2) 血浆内共筛选到27个定性差异代谢物，其中3个与糖代谢相关、10个与脂代谢相关、5个与蛋白代谢相关，1个为三羧酸循环中间代谢物，表明急性和慢性应激均显著改变了能量代谢状态，所检测的代谢物和代谢酶指标在血液、肝脏和肌肉变化显著，而大脑和心脏趋于稳定，说明应激反应过程中代谢特征变化具明显的组织特异性；(3) 急性应激后，机体血糖升高、脂代谢的增强、血浆柠檬酸含量增加，说明显著提高了能量代谢水平；慢性应激可导致机体糖代谢紊乱（血糖升高，肝糖异生和糖酵解显著增强），胸肌葡萄糖含量增加、胸肌、肝糖原储量显著提高，机体脂肪和胆固醇合成增加，说明脂代谢朝合成方向偏移，并显著提高机体整体能量代谢水平；(4) 树麻雀在急性和慢性刺激条件下肝脏内表现强烈的氧化应激反应和氧化损伤，急性刺激条件下提高了超氧化物歧化酶活性与维生素C含量增强了抗氧化能力，慢性应激初期抗氧化系统增加了氧化氢酶活性及维生素C含量，后期依靠升高超氧化物歧化酶活性及谷胱甘肽含量应对氧化应激。研究结果对揭示鸟类从野生到笼养状态的生理适应策略及相应的分子机理具有重要意义，对制定动物的人工驯化和易地保护策略具有潜在的应用价值。