Pusch Elizabeth A, Bentz Alexandra B, Becker Daniel J, Navara Kristen J
Department of Poultry Science, The University of Georgia, Athens, GA 30602, USA.
Odum School of Ecology, The University of Georgia, Athens, GA 30602, USA; Center for the Ecology of Infectious Disease, The University of Georgia, Athens, GA 30602, USA.
Gen Comp Endocrinol. 2018 Jan 1;255:71-77. doi: 10.1016/j.ygcen.2017.10.008. Epub 2017 Oct 16.
Animal species display significant variation in personality traits among individuals, and two main coping styles have been identified and termed "proactive" and "reactive". Further, these coping styles appear to correlate directly with the strength of the physiological stress response exhibited by those individuals. In our study system, white laying hens are reactive, flighty, and exhibit large hormonal and behavioral responses to acute stress, while brown laying hens are proactive, exploratory, and exhibit low hormonal and behavioral responses to acute stress. The objective of the current study was to determine if personality type also corresponds to differences in multiple measures of stress when birds are subjected to a chronic stressor. We tested the responses of hens to chronic stress applied by providing feed according to an unpredictable schedule for 14 days, and measured corticosterone concentrations in circulation, expression of heat shock proteins (HSPs), molecules known to protect cells in response to stress, and the ratios of heterophils:lymphocytes in blood, two immune cells known to change in quantity in circulation during chronic stress. We predicted that white hens would show greater physiological responses to the chronic stress treatment. Plasma corticosterone levels significantly increased after 7 days of treatment and returned to baseline levels on day 14, but did not differ significantly between strains. H:L ratios, on the other hand, were significantly elevated by day 7 of treatment, and increased significantly more in brown hens than white. HSP70 and HSP90 expression levels were significantly higher after stress began in white hens than brown. Our results showed that brown hens were more reactive in one response (H:L ratios) while white hens were more reactive in another (HSP expression). These different reactions to the same stressor may represent different strategies for dealing with the same stressor.
动物物种在个体的性格特征方面表现出显著差异，并且已经识别出两种主要的应对方式，分别称为“主动型”和“反应型”。此外，这些应对方式似乎与个体所表现出的生理应激反应强度直接相关。在我们的研究系统中，白色蛋鸡具有反应型、易受惊的特点，并且对急性应激表现出强烈的激素和行为反应，而棕色蛋鸡则具有主动型、爱探索的特点，并且对急性应激表现出较弱的激素和行为反应。本研究的目的是确定当鸟类受到慢性应激源刺激时，性格类型是否也与多种应激指标的差异相对应。我们通过按照不可预测的时间表提供饲料14天来测试母鸡对慢性应激的反应，并测量循环中的皮质酮浓度、热休克蛋白（HSPs）的表达，热休克蛋白是已知的在应激反应中保护细胞的分子，以及血液中嗜异性粒细胞与淋巴细胞的比例，这两种免疫细胞在慢性应激期间循环中的数量会发生变化。我们预测白色母鸡对慢性应激处理会表现出更大的生理反应。处理7天后血浆皮质酮水平显著升高，并在第14天恢复到基线水平，但不同品系之间没有显著差异。另一方面，处理第7天时H:L比值显著升高，并且棕色母鸡的升高幅度显著大于白色母鸡。应激开始后，白色母鸡中HSP70和HSP90的表达水平显著高于棕色母鸡。我们的结果表明，棕色母鸡在一种反应（H:L比值）中反应更强，而白色母鸡在另一种反应（HSP表达）中反应更强。对同一应激源的这些不同反应可能代表了应对同一应激源的不同策略。
