Ivy Catherine M, Robertson Cayleih E, Bernier Nicholas J
Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Proc Biol Sci. 2017 Jan 11;284(1846). doi: 10.1098/rspb.2016.1868.
Eutrophication and climate change are increasing the incidence of severe hypoxia in fish nursery habitats, yet the programming effects of hypoxia on stress responsiveness in later life are poorly understood. In this study, to investigate whether early hypoxia alters the developmental trajectory of the stress response, zebrafish embryos were exposed to 4 h of anoxia at 36 h post-fertilization and reared to adults when the responses to secondary stressors were assessed. While embryonic anoxia did not affect basal cortisol levels or the cortisol response to hypoxia in later life, it had a marked effect on the responses to a social stressor. In dyadic social interactions, adults derived from embryonic anoxia initiated more chases, bit more often, entered fewer freezes and had lower cortisol levels. Adults derived from embryonic anoxia also performed more bites towards their mirror image, had lower gonadal aromatase gene expression and had higher testosterone levels. We conclude that acute embryonic anoxia has long-lasting consequences for the hormonal and behavioural responses to social interactions in zebrafish. Specifically, we demonstrate that acute embryonic anoxia favours the development of a dominant and aggressive phenotype, and that a disruption in sex steroid production may contribute to the programming effects of environmental hypoxia.
富营养化和气候变化正在增加鱼类育苗栖息地严重缺氧的发生率，然而，缺氧对后期生活中应激反应的编程效应却知之甚少。在本研究中，为了探究早期缺氧是否会改变应激反应的发育轨迹，在受精后36小时将斑马鱼胚胎暴露于缺氧环境4小时，并饲养至成年后评估其对二次应激源的反应。虽然胚胎期缺氧并不影响成年后的基础皮质醇水平或对缺氧的皮质醇反应，但对社交应激源的反应有显著影响。在二元社交互动中，胚胎期缺氧的成年鱼发起更多追逐、更频繁撕咬、较少静止不动且皮质醇水平较低。胚胎期缺氧的成年鱼对其镜像也有更多撕咬行为，性腺芳香化酶基因表达较低且睾酮水平较高。我们得出结论，急性胚胎期缺氧对斑马鱼社交互动的激素和行为反应具有长期影响。具体而言，我们证明急性胚胎期缺氧有利于主导和攻击型表型的发育，并且性类固醇生成的破坏可能导致环境缺氧的编程效应。
