Li Y, Isomaa V, Pulkka A, Herva R, Peltoketo H, Vihko P
Biocenter Oulu and Research Center for Molecular Endocrinology, WHO Collaborating Centre for Research on Reproductive Health, University of Oulu, FIN-90014 Oulu, Finland.
Placenta. 2005 May;26(5):387-92. doi: 10.1016/j.placenta.2004.07.008.
The placenta is responsible for the production of progesterone (P) and estrogens during human pregnancy. In this study, the expression of several key steroidogenic enzymes was investigated in different cell types of human placenta during early and mid-gestation by in situ hybridization. 3Beta-hydroxysteroid dehydrogenase type 1 (3beta-HSD1), P450 aromatase (P450arom) and 17beta-hydroxysteroid dehydrogenase type 1 (17HSD1) were expressed abundantly in syncytiotrophoblast (ST) cells. These three enzymes were also detected in some column cytotrophoblast (CCT) cells. 17HSD5 was found in intravillous stromal (IS) cells in low levels, suggesting that androgens may be synthesized and metabolized in the placenta. 17HSD7 was found in all types of placental cells. Moreover, 17HSD2 was localized in IS cells. The expression level of 17HSD2 gradually increased during pregnancy weeks 7-16, concurrently with the androgen production by the male fetus. The present study provides evidence that CCT and IS cells participate in P and estrogen biosynthesis, in addition to ST cells. 17HSD2 also converts 20alpha-dihydroprogesterone (20-OH-P) to P, whereas 17HSD5 and 17HSD7 inactivate P. Therefore, the action of 3beta-HSD1 and 17HSD2 on P biosynthesis in the placenta is countered by 17HSD5 and 17HSD7, which may provide an optimal level of P for the maintenance and progression of pregnancy.
胎盘负责在人类孕期产生孕酮（P）和雌激素。在本研究中，通过原位杂交研究了妊娠早期和中期人胎盘不同细胞类型中几种关键类固醇生成酶的表达。1型3β-羟基类固醇脱氢酶（3β-HSD1）、细胞色素P450芳香化酶（P450arom）和1型17β-羟基类固醇脱氢酶（17HSD1）在合体滋养层（ST）细胞中大量表达。这三种酶在一些柱状细胞滋养层（CCT）细胞中也被检测到。17HSD5在绒毛间质（IS）细胞中低水平表达，提示胎盘可能合成和代谢雄激素。在所有类型的胎盘细胞中均发现了17HSD7。此外，17HSD2定位于IS细胞。在妊娠第7至16周期间，17HSD2的表达水平逐渐升高，与此同时男性胎儿产生雄激素。本研究提供了证据表明，除了ST细胞外，CCT和IS细胞也参与孕酮和雌激素的生物合成。17HSD2还将20α-二氢孕酮（20-OH-P）转化为孕酮，而17HSD5和17HSD7使孕酮失活。因此，17HSD5和17HSD7抵消了3β-HSD1和17HSD2对胎盘孕酮生物合成的作用，这可能为维持和促进妊娠提供最佳水平的孕酮。
