Effect of chronic crowding and cold on the pituitary-adrenal system: responsiveness to an acute stimulus during chronic stress.
Effect of chronic crowding and cold on the pituitary-adrenal system: responsiveness to an acute stimulus during chronic stress.
复制标题
慢性拥挤和寒冷对垂体肾上腺系统的影响：慢性应激期间对急性刺激的反应。
作者：
A. Daniels;A. Goodwin;L. Keil;J. Vernikos‐Danellis
在8周的时间里，对雄性大鼠长期暴露于拥挤或冷应激的影响进行了评估。两种条件都抑制了身体的生长。两组治疗2周后，垂体前叶重量均有所下降，但8周时，冷暴露大鼠的腺体肥大。寒冷导致持续的肾上腺和睾丸肥大，而拥挤没有这种影响。血浆和肾上腺皮质酮水平在寒冷或拥挤1周后升高，仅在寒冷暴露的动物中，8周后显著降低。血浆ACTH保持不变，直到8周后，两组动物的ACTH开始升高。在这些实验中获得的数据表明，至少在研究的8周暴露期间，垂体-肾上腺系统对慢性应激的反应既不是稳定在一个新的稳定状态，也不是恢复到正常状态。这些长期应激动物对额外急性应激刺激（1分钟乙醚）的反应性也进行了评估。拥挤降低了血浆和肾上腺皮质酮对乙醚麻醉1周的反应。在研究的所有时间间隔（1 - 8周），冷暴露均增强血浆皮质酮反应，并在第1周和第2周增强ACTH反应。
The effects of chronic exposure to crowding or cold stress were assessed in male rats over a period of 8 weeks. Body growth was inhibited by both conditions. Anterior pituitary weights decreased after 2 weeks of either treatment, but by 8 weeks the glands of cold exposed rats had hypertrophied. Cold resulted in a sustained adrenal and testicular hypertrophy, whereas crowding had no such effect. Plasma and adrenal corticosterone levels were elevated after 1 week of cold or crowding, followed by a marked reduction after 8 weeks in cold-exposed animals only. Plasma ACTH remained unchanged until 8 weeks when it started rising in both groups of animals. The data obtained in these experiments indicate that the pituitary-adrenal system responds to chronic stress neither by stabilization at a new steady state nor by a return to a period of normalcy, at least within the 8 weeks of exposure studied. The responsiveness of these chronically stressed animals to an additional acute stressful stimulus (1 min of ether) was also evaluated. Crowding depressed both the plasma and adrenal corticosterone response to ether anesthesia at 1 week. Cold exposure enhanced the plasma corticosterone response at all intervals (1–8 weeks) studied and enhanced the ACTH response at 1 and 2 weeks.