Schäfer H H, Gebhart V M, Hertel K, Jirikowski G F
Institute of Anatomy II, University Hospital Jena, Friedrich Schiller University, Jena, Germany.
Institute of Pathology, HELIOS Klinikum Erfurt, Erfurt, Germany.
Horm Metab Res. 2015 Jul;47(8):596-9. doi: 10.1055/s-0034-1389957. Epub 2014 Sep 24.
Glucocorticoids are known to be involved in myocardial regeneration and destruction. Cardiomyocytes are mostly devoid of nuclear glucocorticoid receptors (GRs) and it is generally assumed that effects of adrenal steroids in heart are mediated through the mineralocorticoid receptor (MR). Here we used immunocytochemistry to study localization of corticosteroid binding globulin (CBG) in semithin sections of human cardiac tissue samples. With staining of consecutive sections we examined colocalization with GR and MR immunoreactivities. While GR staining was almost undetectable, a portion of myocytes with MR immunostained nuclei was found. Almost all cardiomyocytes exhibited CBG immunostaining in cytoplasm and on the cell membrane. Most pronounced CBG immunoreactivities were found in Purkinje fibers and in smooth muscle cells of arterial walls. With RT-PCR, we found in homogenates of cardiac tissue detectable levels of CBG encoding mRNA. Our findings indicate that CBG is expressed in human heart. Known cardiac effects of adrenal steroids may in part be mediated through the binding globulin and its putative membrane receptor in addition to nuclear steroid receptors and direct genomic action. Highlights of our study: Human cardiomyocytes express mineralocorticoid receptors, but are mostly free of nuclear glucocorticoid receptors. CBG is expressed in myocardium and in Purkinje fibers. CBG in heart is colocalized with mineralocorticoid receptor. Endothelia and smooth muscle cells of arterial walls show colocalization of CBG and MR.
已知糖皮质激素参与心肌再生与破坏过程。心肌细胞大多缺乏核糖皮质激素受体（GRs），人们普遍认为肾上腺类固醇在心脏中的作用是通过盐皮质激素受体（MR）介导的。在此，我们采用免疫细胞化学方法研究皮质类固醇结合球蛋白（CBG）在人类心脏组织样本半薄切片中的定位。通过对连续切片进行染色，我们检测了其与GR和MR免疫反应性的共定位情况。虽然几乎检测不到GR染色，但发现一部分心肌细胞核有MR免疫染色。几乎所有心肌细胞在细胞质和细胞膜上均呈现CBG免疫染色。在浦肯野纤维和动脉壁平滑肌细胞中发现了最为明显的CBG免疫反应性。通过逆转录聚合酶链反应（RT-PCR），我们在心脏组织匀浆中检测到了可检测水平的CBG编码mRNA。我们的研究结果表明，CBG在人类心脏中表达。肾上腺类固醇已知的心脏效应，除了通过核类固醇受体和直接的基因组作用外，可能部分是通过结合球蛋白及其假定的膜受体介导的。我们研究的重点：人类心肌细胞表达盐皮质激素受体，但大多不含核糖皮质激素受体。CBG在心肌和浦肯野纤维中表达。心脏中的CBG与盐皮质激素受体共定位。动脉壁的内皮细胞和平滑肌细胞显示CBG和MR共定位。
