Department of Biology, Tufts University, Medford, MA 02155, USA.
Department of Biology, Tufts University, Medford, MA 02155, USA.
Horm Behav. 2019 Jun;112:81-88. doi: 10.1016/j.yhbeh.2019.04.009. Epub 2019 Apr 18.
A number of studies have shown that chronic stress can negatively impact both physiology and behavior in a variety of organisms. What has yet to be extensively explored is whether these changes permanently alter an animal's functioning, or if they can be reversed. In this study, we used wild-caught house sparrows (Passer domesticus) to assess how recovery periods influence the physiological and behavioral impacts of an initial four days and subsequent four days of repeated stressors. Birds were randomly assigned to a recovery group and either experienced 0, 24, or 72 h of recovery between the two sets of stressors (cage rolling and cage tapping). We measured the regulation of the hypothalamic pituitary adrenal (HPA) axis by quantifying baseline and stress-induced corticosterone as well as negative feedback strength. We also assessed behavior using neophobia trials to measure how birds altered their approach towards novel objects and their overall activity. Both behavior and corticosterone responses were assessed before the experiment, after the recovery time, and following the final 4 days of stressors. We found that birds that experienced 24 h of recovery had reduced stress-induced corticosterone, but enhanced negative feedback relative to the pre-experiment sample. Additionally, 4 days of stressors was enough to significantly reduce approach latency towards novel objects; however, pre-experiment levels returned with longer periods of recovery. Finally, recovery time did not significantly influence responses to the second 4 days of stressors. Our results indicate that brief recovery periods partially ameliorate the hormonal and behavioral effects of repeated stress.
一些研究表明，慢性压力会对各种生物体的生理和行为产生负面影响。目前尚未广泛探讨的是这些变化是否会永久性地改变动物的功能，或者它们是否可以逆转。在这项研究中，我们使用野生捕获的家麻雀（Passer domesticus）来评估恢复期如何影响初始四天和随后四天重复应激源对生理和行为的影响。鸟类被随机分配到恢复期组，在两组应激源（笼滚和笼敲）之间经历 0、24 或 72 小时的恢复期。我们通过量化基础和应激诱导的皮质酮以及负反馈强度来测量下丘脑垂体肾上腺 (HPA) 轴的调节。我们还使用新恐惧症试验来评估行为，以测量鸟类如何改变对新物体的接近度和整体活动。在实验之前、恢复期之后以及最后四天的应激源之后，我们评估了行为和皮质酮反应。我们发现，经历 24 小时恢复期的鸟类应激诱导的皮质酮水平降低，但与实验前样本相比，负反馈增强。此外，4 天的应激源足以显著降低对新物体的接近潜伏期；然而，随着恢复期的延长，恢复到实验前的水平。最后，恢复期时间并未显著影响对第二组 4 天应激源的反应。我们的研究结果表明，短暂的恢复期部分减轻了重复应激的激素和行为影响。
