Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, Tartu 51014, Estonia.
Horm Behav. 2010 Apr;57(4-5):481-7. doi: 10.1016/j.yhbeh.2010.02.006. Epub 2010 Feb 18.
The extended secretion of stress hormones in fully developed animals is known to have profound consequences. However, little is known about the effects of stress on the behavior and physiology of free-living young animals, and how such responses relate to each other. We repeatedly (during 5 consecutive days, 1 h/day) exposed the nestlings of a passerine bird, the pied flycatcher (Ficedula hypoleuca), to recordings of nestling distress calls and examined their behavioral and physiological responses to the stressor on the first and the last day of the experiment (on days 9 and 13 post-hatch, respectively). In comparison with control siblings, stressed nestlings reduced the amount of time that they devoted to vocalization and locomotion and increased levels of circulating corticosterone. In 9-day-old nestlings, the level of stress-induced hormone was negatively related to locomotor activity, but not to the rate of vocalizations. The repeated presentation of the stressor increased the heterophile-to-lymphocyte ratio in nestlings but did not affect nestling growth rate. In 13-day-old nestlings, the level of stress-induced corticosterone was not related to behavioral activity. These results suggest that the high level of corticosterone released by immature nestlings in response to a stressor may promote anti-predator behavior (e.g., passive avoidance behavior). Moreover, repeatedly induced stress may have a cumulative and potentially negative effect on individual physiology.
已知完全发育的动物中应激激素的延长分泌会产生深远的影响。然而，人们对压力对自由生活的幼小动物的行为和生理的影响知之甚少，也不知道这些反应彼此之间有何关联。我们反复（在连续 5 天内，每天 1 小时）将雀形目鸟类白腰文鸟（Ficedula hypoleuca）的雏鸟暴露于雏鸟求救叫声的录音中，并在实验的第一天和最后一天（分别在孵化后的第 9 天和第 13 天）检查它们对压力源的行为和生理反应。与对照的兄弟姐妹相比，应激的雏鸟减少了发声和运动的时间，增加了循环皮质酮的水平。在 9 日龄的雏鸟中，应激诱导的激素水平与运动活性呈负相关，但与发声率无关。应激源的重复呈现增加了雏鸟的异嗜性白细胞与淋巴细胞的比值，但不影响雏鸟的生长速度。在 13 日龄的雏鸟中，应激诱导的皮质酮水平与行为活动无关。这些结果表明，不成熟的雏鸟对压力源释放的高水平皮质酮可能会促进抗捕食行为（例如，被动回避行为）。此外，反复引起的压力可能对个体生理产生累积的、潜在的负面影响。
