Dickens M, Romero L M, Cyr N E, Dunn I C, Meddle S L
Department of Biology, Tufts University, Medford, MA 02155, USA.
J Neuroendocrinol. 2009 Oct;21(10):832-40. doi: 10.1111/j.1365-2826.2009.01908.x. Epub 2009 Aug 4.
Although the glucocorticoid response to acute short-term stress is an adaptive physiological mechanism that aids in the response to and survival of noxious stimuli, chronic stress is associated with a negative impact on health. In wild-caught European starlings (Sturnus vulgaris), chronic stress alters the responsiveness of hypothalamic-pituitary-adrenal (HPA) axis as measured by the acute corticosterone response. In the present study, we investigated potential underlying neuroendocrine mechanisms by comparing glucocorticoid receptor and mineralocorticoid receptor mRNA expression in the brains of chronically and nonchronically-stressed starlings. Hypothalamic paraventricular nucleus, but not hippocampal, glucocorticoid receptor mRNA expression in chronically-stressed birds was significantly lower compared to controls, suggesting changes in the efficacy of corticosterone negative feedback. In addition, chronically-stressed birds showed a significant decrease in hippocampal MR mRNA expression. Together, these results suggest that chronic stress changes the brain physiology of wild birds and provides important information for the understanding of the underlying mechanisms that result in dysregulation of the HPA axis in wild animals by chronic stress.
尽管糖皮质激素对急性短期应激的反应是一种适应性生理机制，有助于机体对有害刺激做出反应并生存下来，但慢性应激会对健康产生负面影响。在野生捕获的欧洲椋鸟（Sturnus vulgaris）中，慢性应激会改变下丘脑-垂体-肾上腺（HPA）轴的反应性，这可通过急性皮质酮反应来衡量。在本研究中，我们通过比较长期应激和非长期应激椋鸟大脑中糖皮质激素受体和盐皮质激素受体mRNA的表达，来研究潜在的神经内分泌机制。与对照组相比，长期应激鸟类下丘脑室旁核而非海马体中的糖皮质激素受体mRNA表达显著降低，这表明皮质酮负反馈的效能发生了变化。此外，长期应激的鸟类海马体MR mRNA表达显著降低。这些结果共同表明，慢性应激会改变野生鸟类的大脑生理，并为理解慢性应激导致野生动物HPA轴失调的潜在机制提供重要信息。
