Sasaki F, Wu P, Rougeau D, Unabia G, Childs G V
Department of Anatomy and Neurosciences, University of Texas Medical Branch, Galveston 77550.
Endocrinology. 1990 Jul;127(1):285-97. doi: 10.1210/endo-127-1-285.
Cold stress stimulates the release of both ACTH and TSH from the pituitary. More striking changes in ACTH content have been seen in the intermediate lobe after cold stress. Therefore, this study was designed to test responses of individual anterior lobe corticotropes to cold exposure. Male rats were exposed to either 30 min of cold (+3-5 C), 30 min of a novel, temperate environment (+24 C) or were unstressed (+24 C). Pituitaries were fixed and embedded in preparation for immunolabeling for ACTH or TSH-beta at the light (semithin sections) and electron microscopic levels. The semithin sections were used to measure areas of corticotropes and thyrotropes with Bioquant image analysis equipment. Separate groups of pituitaries were dissociated and the cells were cultured for 2 or 15 h. Then the cells were stimulated for 5-10 min with biotinylated analogs of corticotropin-releasing hormone (bio-CRH) or arginine vasopressin (bio-AVP) to detect the target cells cytochemically. A third group of dissociated cells were fixed for immunolabeling for ACTH, 16K fragment of pro-opiomelanocortin, beta-endorphin, or TSH-beta. Cold exposure resulted in a 1-4-fold increase in the levels of serum ACTH over that of unstressed rats. This was correlated with a 40% increase in the percentage of cells that contained 16K fragment and a 30-40% increase in percentages of cells storing ACTH or beta-endorphin. Cold stress also increased the percentage of cells that bound bio-CRH or bio-AVP by 45%. Analyses of semithin sections showed that areas of corticotropes increased by 21% following cold stress. The number of rows of immunolabeled (ACTH) secretion granules also increased in corticotropes from cold-stressed rats. Exposure to a novel environment for 30 min resulted in no significant increase in serum ACTH over that of unstressed rats. There was, however, a 20% increase in percentages of cells that stored 16K fragment, beta-endorphin, or target cells that bound bio-CRH. However, the corticotropes were not significantly larger. Many of the cells exhibited reduced numbers of immunolabeled secretory granules. Other corticotropes resembled those from cold-stressed rats. When TSH cells were studied, their percentages increased from 8 +/- 3% to 15.8 +/- 4% and their areas increased by 22% following exposure to cold. After exposure to a novel environment, percentages of cells that stored TSH-beta increased to 11 +/- 2%, however, no changes in areas of TSH cells were measured. These studies demonstrated that the anterior lobe corticotrope is clearly activated by exposure to both cold and novel environment.(ABSTRACT TRUNCATED AT 400 WORDS)
冷应激会刺激垂体释放促肾上腺皮质激素（ACTH）和促甲状腺激素（TSH）。冷应激后，垂体中间叶的ACTH含量变化更为显著。因此，本研究旨在测试单个垂体前叶促肾上腺皮质激素细胞对冷暴露的反应。将雄性大鼠暴露于3℃-5℃的寒冷环境30分钟、24℃的新的常温环境30分钟或不施加应激（24℃）。将垂体固定并包埋，以便在光学（半薄切片）和电子显微镜水平进行ACTH或TSH-β的免疫标记。使用Bioquant图像分析设备，通过半薄切片测量促肾上腺皮质激素细胞和促甲状腺激素细胞的面积。将单独的垂体组进行解离，并将细胞培养2或15小时。然后用促肾上腺皮质激素释放激素（bio-CRH）或精氨酸加压素（bio-AVP）的生物素化类似物刺激细胞5-10分钟，以进行细胞化学检测靶细胞。第三组解离细胞进行固定，用于ACTH、阿黑皮素原的16K片段、β-内啡肽或TSH-β的免疫标记。与未受应激的大鼠相比，冷暴露导致血清ACTH水平升高1-4倍。这与含有16K片段的细胞百分比增加40%以及储存ACTH或β-内啡肽的细胞百分比增加30%-40%相关。冷应激还使结合bio-CRH或bio-AVP的细胞百分比增加了45%。半薄切片分析表明，冷应激后促肾上腺皮质激素细胞的面积增加了21%。冷应激大鼠的促肾上腺皮质激素细胞中，免疫标记（ACTH）分泌颗粒的行数也增加了。暴露于新环境30分钟后，与未受应激的大鼠相比，血清ACTH没有显著增加。然而，储存16K片段、β-内啡肽的细胞百分比或结合bio-CRH的靶细胞百分比增加了20%。然而，促肾上腺皮质激素细胞没有显著变大。许多细胞的免疫标记分泌颗粒数量减少。其他促肾上腺皮质激素细胞与冷应激大鼠的相似。当研究促甲状腺激素细胞时，暴露于寒冷后，它们的百分比从8±3%增加到15.8±4%，面积增加了22%。暴露于新环境后，储存TSH-β的细胞百分比增加到11±2%，然而，促甲状腺激素细胞的面积没有变化。这些研究表明，垂体前叶促肾上腺皮质激素细胞在暴露于寒冷和新环境时均明显被激活。（摘要截取自400字）
