Yang K, Langlois D A, Campbell L E, Challis J R, Krkosek M, Yu M
Lawson Research Institute, St Joseph's Hospital, Department of Ob/Gyn, University of Western Ontario, London, Canada.
Placenta. 1997 Sep;18(7):503-9. doi: 10.1016/0143-4004(77)90003-0.
This study was designed to examine the cellular localization and developmental regulation of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) type 1 gene expression in the ovine placenta. Placental tissues were collected at discrete times between days 59 and 143 of pregnancy (term = 145 days). Levels of 11 beta-HSD1 mRNA were determined by Norther blot analysis. The level of both dehydrogenase and reductase activities of 11 beta-HSD1 was assessed by a radiometric conversion assay using cortisol and cortisone as physiological substrates. The cellular localization of 11 beta-HSD1 protein was determined by standard immunohistochemical technique using a polyclonal antibody specific for the ovine protein. High levels of 11 beta-HSD1 mRNA were detected in the placenta by day 59, and there was a trend towards a decrease between days 98-103 and 125-128 (P = 0.06). The level of placental 11 beta-HSD1 mRNA remained unchanged thereafter. Levels of both 11 beta-HSD1 dehydrogenase and reductase activities followed a similar pattern except that in both cases there was a significant decrease between 98-103 and 125-128 (P < 0.05). Moreover, under the present assay conditions, the dehydrogenase activity was always predominant, suggesting that the net effect of placental 11 beta-HSD1 activity would lead to glucocorticoid inactivation. Thus, the decreased 11 beta-HSD1 activity in the placenta at days 125-128 was consistent with, and may help to explain, the apparent increase in the placental transfer of cortisol from mother to fetus during that time. Throughout pregnancy, intense 11 beta-HSD1 immunoreactivity was detected in fetal trophoblastic cells, maternal stromal cells and blood vessels. In contrast, maternal syncytium was immunonegative before day 125, but became immunopositive thereafter. The observed predominant direction of 11 beta-HSD1 activity in vitro and its pattern of localization in the ovine placenta are consistent with the hypothesis that placental 11 beta-HSD protects the fetus from adverse effects of maternal glucocorticoids by inactivating glucocorticoids locally.
本研究旨在检测绵羊胎盘组织中11β-羟类固醇脱氢酶（11β-HSD）1型基因表达的细胞定位及其发育调控情况。在妊娠第59天至143天（足月为145天）期间的不同时间点采集胎盘组织。通过Northern印迹分析测定11β-HSD1 mRNA水平。以皮质醇和可的松作为生理底物，采用放射性转化分析法评估11β-HSD1的脱氢酶和还原酶活性水平。使用针对绵羊蛋白的多克隆抗体，通过标准免疫组织化学技术确定11β-HSD1蛋白的细胞定位。在第59天时，在胎盘中检测到高水平的11β-HSD1 mRNA，在第98 - 103天和125 - 128天之间有下降趋势（P = 0.06）。此后，胎盘11β-HSD1 mRNA水平保持不变。11β-HSD1脱氢酶和还原酶活性水平呈现相似模式，只是在这两种情况下，在第98 - 103天和125 - 128天之间均有显著下降（P < 0.05）。此外，在当前检测条件下，脱氢酶活性始终占主导，这表明胎盘11β-HSD1活性的净效应会导致糖皮质激素失活。因此，在第125 - 128天胎盘11β-HSD1活性降低与该时期皮质醇从母体向胎儿胎盘转运的明显增加一致，并且可能有助于解释这一现象。在整个孕期，在胎儿滋养层细胞、母体基质细胞和血管中均检测到强烈的11β-HSD1免疫反应性。相比之下，母体合体滋养层在第125天之前呈免疫阴性，但此后变为免疫阳性。体外观察到的11β-HSD1活性的主要方向及其在绵羊胎盘中的定位模式与胎盘11β-HSD通过局部使糖皮质激素失活来保护胎儿免受母体糖皮质激素不良影响这一假说一致。
