Department of Pediatrics and Adolescent Medicine, University Erlangen-Nuremberg, Erlangen, Germany.
Nephrol Dial Transplant. 2010 Oct;25(10):3195-203. doi: 10.1093/ndt/gfq354. Epub 2010 Jun 21.
Intrauterine growth restriction (IUGR) is associated with systemic hypertension of the offspring later in life. The exact mechanisms are still incompletely understood. 11β-Hydroxysteroid dehydrogenase 2 (11β-HSD2) in the distal renal tubule protects the mineralocorticoid receptor from cortisol. As we did not find a suppression of 11β-HSD2 in total kidney of IUGR animals, our objective was to investigate whether a suppression of 11β-HSD2 could be detected on a more sophisticated level such as in situ protein and gene expression of 11β-HSD2 in mildly hypertensive IUGR offspring.
IUGR rats after maternal low-protein diet (n = 17) were compared with controls (n = 18). At 70 and 120 days of age, in situ distribution of 11β-HSD2 gene and protein expression was investigated by RT-PCR of microdissected tubules and immunohistochemistry. For in situ localization studies, double staining for 11β-HSD2 and calbindin was used. Serum levels of corticosterone and dehydrocorticosterone were measured by tandem mass spectrometry.
In IUGR rats, intra-arterial blood pressure significantly increased at Day 120 of life. Serum corticosterone/dehydrocorticosterone ratios and 11β-HSD2 mRNA in total kidney were not altered in IUGR animals. However, 11β-HSD2 mRNA concentration was significantly lower in microdissected tubuli of IUGR animals (Day 120: 0.18 ± 0.14 vs 1.00 ± 0.32 rel. units in controls; P < 0.05). In IUGR animals, immunostaining scores for 11β-HSD2 were significantly lower than in controls (P < 0.05). Double staining with calbindin showed lower expression of 11β-HSD2 in distal segments of the distal tubule.
Our data indicate lower gene and protein expression of the pre-receptor enzyme 11β-HSD2 in IUGR animals when looking at specific renal compartments, but not in total kidney extracts. Thus, lower 11β-HSD2 as a mechanism for hypertension later in life might be missed without methods for in situ detection.
宫内生长受限（IUGR）与后代生命后期的系统性高血压有关。确切的机制仍不完全清楚。在远端肾小管中，11β-羟类固醇脱氢酶 2（11β-HSD2）可保护盐皮质激素受体免受皮质醇的影响。由于我们没有发现 IUGR 动物的总肾脏中 11β-HSD2 的抑制，因此我们的目的是研究在更复杂的水平（如轻度高血压 IUGR 后代的原位 11β-HSD2 蛋白和基因表达）上是否可以检测到 11β-HSD2 的抑制。
比较了低蛋白饮食后 IUGR 大鼠（n = 17）与对照组（n = 18）。在 70 和 120 天龄时，通过微切割管的 RT-PCR 和免疫组织化学法研究了原位 11β-HSD2 基因和蛋白表达的分布。进行原位定位研究时，使用 11β-HSD2 和钙结合蛋白的双重染色。通过串联质谱法测量血清皮质酮和脱氢皮质酮的水平。
在 IUGR 大鼠中，生命第 120 天的动脉血压显着升高。IUGR 动物的血清皮质酮/脱氢皮质酮比值和总肾脏中的 11β-HSD2 mRNA 没有改变。然而，微切割管中的 11β-HSD2 mRNA 浓度在 IUGR 动物中显着降低（第 120 天：0.18 ± 0.14 与对照组的 1.00 ± 0.32 相对单位；P < 0.05）。IUGR 动物的 11β-HSD2 免疫染色评分明显低于对照组（P < 0.05）。与钙结合蛋白的双重染色显示，远端肾小管的远端部分 11β-HSD2 的表达降低。
我们的数据表明，在观察特定的肾脏隔室时，IUGR 动物的前受体酶 11β-HSD2 的基因和蛋白表达较低，但在总肾脏提取物中则没有。因此，如果没有原位检测方法，可能会错过作为以后发生高血压的机制的较低的 11β-HSD2。
