INRA, UMR85 Physiologie de la Reproduction et des Comportements F-37380 Nouzilly, France.
Behav Brain Res. 2011 Dec 1;225(2):505-10. doi: 10.1016/j.bbr.2011.08.010. Epub 2011 Aug 19.
There is considerable variability in the susceptibility of individuals to the adverse effects of chronic stress. In humans and other mammals, individual traits such as high anxiety are proposed as a vulnerability factor for the development of stress-related disorders. In the present study, we tested whether a similar behavioural trait in birds, higher emotional reactivity, also favours the occurrence of chronic stress-related behavioural and physiological dysfunction. For this, lines of Japanese quail divergently selected for a typical fear response in birds, the duration of tonic immobility, were subjected to unpredictable aversive stimulation over 2 weeks. Previous studies demonstrate that the selection program modifies the general underlying emotionality of the birds rather than exerting its effect only on tonic immobility. Interestingly, only birds selected for their higher emotionality exhibited significantly enhanced latency to first step and decreased locomotor activity in the open-field test after exposure to chronic stress compared to non-stressed control birds. This effect of chronic stress was selective for the tested dimension of bird emotional reactivity because there was no observed effect on the tonic immobility response. Moreover, chronically stressed birds selected for their higher emotionality exhibited significantly decreased basal corticosterone levels, a physiological marker of stress. These findings show that chronic stress is associated with changes in emotional reactivity and related physiological markers in birds. They also highlight emotional reactivity as an important predisposing factor for the occurrence of the adverse effects of chronic stress in birds.
个体对慢性应激的不良反应的易感性存在相当大的可变性。在人类和其他哺乳动物中，高焦虑等个体特征被认为是应激相关障碍发展的脆弱因素。在本研究中，我们测试了鸟类中类似的行为特征，即更高的情绪反应性，是否也有利于慢性应激相关行为和生理功能障碍的发生。为此，我们对日本鹌鹑进行了选择，这些鹌鹑在鸟类中表现出典型的恐惧反应，即强直不动的持续时间，在 2 周内接受不可预测的厌恶刺激。先前的研究表明，选择方案改变了鸟类的一般潜在情绪，而不仅仅是对强直不动产生影响。有趣的是，与未受应激的对照鸟类相比，只有选择具有更高情绪性的鸟类在经历慢性应激后，在首次踏足的潜伏期和旷场测试中的运动活性显著降低。慢性应激的这种影响是针对鸟类情绪反应性的测试维度选择性的，因为在强直不动反应中没有观察到这种影响。此外，选择具有更高情绪性的慢性应激鸟类表现出明显降低的基础皮质酮水平，这是应激的生理标志物。这些发现表明，慢性应激与鸟类情绪反应性和相关生理标志物的变化有关。它们还强调了情绪反应性作为鸟类慢性应激不良反应发生的重要诱发因素。
