Site of thyroxine-evoked decrease of jejunal lactase in the rat.
Site of thyroxine-evoked decrease of jejunal lactase in the rat.
复制标题
甲状腺素引起大鼠空肠乳糖酶降低的部位。
DOI：
10.1152/ajpgi.1982.243.5.g359
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Koldovsky,O
中科院分区：
文献类型：
--
作者：
Boyle,JT;Kelly,K;Krulich,L;Koldovsky,O
在首次注射L-甲状腺素（200 μ g/100 g体重，每24 h一次）后24和48 h，研究了甲状腺介导的乳糖酶活性沿着成年大鼠空肠绒毛-隐窝单位降低的定位。在首次注射甲状腺素时也给予[3 H]胸苷。血清促甲状腺激素、摄食量和体重在24 h内显著降低。总空肠蛋白质和绒毛隐窝高度在研究期间没有变化。24 h内，空肠和空肠中段的乳糖酶活性（以组织蛋白和肠段表达）均显著降低。连续切片的空肠绒毛隐窝单位在低温恒温器中显示，乳糖酶活性降低的网站在24小时是在顶端绒毛和48小时延长沿着整个高度的绒毛。通过组织放射自显影术和[3 H]胸苷闪烁计数法测定的冷冻切片中的上皮细胞迁移显示，在24和48 h时，对照组和甲状腺给药组动物之间无差异。乳糖酶活性在24小时的下降是在放射性的前沿，表明甲状腺诱发的反应发生在成熟的肠上皮细胞已经在绒毛。
Localization of thyroid-mediated decrease of lactase activity along the villus-crypt unit in adult rat jejunum was studied 24 and 48 h after first injection of L-thyroxine (200 micrograms/100 g body wt) every 24 h. [3H]thymidine was also given at time of first thyroxine injection. Serum thyroid-stimulating hormone, food intake, and body weight were significantly decreased within 24 h. Total jejunal protein and villus-crypt height were unchanged during the time period studied. Lactase activity (expressed both as per tissue protein and per intestinal segment) was significantly decreased in jejunum and midjejunum within 24 h. Serial sectioning of the jejunal villus-crypt unit in a cryostat showed that the site of decrease in lactase activity at 24 h was in the apical villus and by 48 h extended along the entire height of the villus. Epithelial cell migration measured both by histoautoradiography and scintillation counting of [3H]thymidine in cryostat sections revealed no difference between control and thyroid-treated animals at both 24 and 48 h. The decrease in lactase activity at 24 h was in advance of the leading edge of radioactivity, indicating that the thyroid-evoked response occurred in mature enterocytes already on the villus.