Thi A D, Jung-Testas I, Baulieu E E
Unité 33 INSERM, University Paris XI, Le Kremlin-Bicêtre, France.
J Steroid Biochem Mol Biol. 1998 Nov;67(3):201-11. doi: 10.1016/s0960-0760(98)00116-2.
Rat glial cells from the central nervous system (CNS) and the peripheral nervous system (PNS) express steroid hormone receptors. Whereas progestin receptors (PR) in cultured glial cells of the CNS are estrogen-inducible, similar increase of PR in cultured Schwann cells, the glial cells of the PNS, prepared from newborn rat sciatic nerves, could not be demonstrated. In the present work we have used fetal dorsal root ganglion cultures to study the effect of estrogen and its antagonist ICI 164,384 on the expression of PR in rat Schwann cells. The PR levels were measured by hormone binding in whole cell assays or in cell cytosol, 18 h after excision of the ganglion from the cultures. Treatment of DRG-Schwann cell cultures with estradiol (E2) increased PR levels from about 60 to 160 fmol per mg cytosol protein, in untreated and estrogen-treated cells, respectively. This increase was dose-dependent; maximal induction was obtained at 50 nM E2-concentration. Treatment of the cultures with the antagonist ICI 164,384 completely inhibited the estrogen-induction of PR, whereas ICI alone did not influence receptor levels in Schwann cells. The estrogen-induction of PR was dependent on the presence of dorsal root ganglion during the period of estrogen treatment. Excision of the neuronal mass from the cultures caused a rapid decrease and disappearance of estrogen-inducible progestin receptors, whereas the concentration of non-inducible PR-binding sites remained unchanged. Estradiol had no influence on DRG-Schwann cell proliferation, only replated secondary Schwann cells showed a slightly higher level of proliferation in presence of 100 nM E2 and 5 microM forskolin. Receptors for estrogen (ER) were also demonstrated in DRG-Schwann cells by ligand binding experiments. Specific ER-binding was 36 +/- 8 fmol bound estradiol per mg cytosol protein. Finally, both PR and ER were visualized in Schwann cells by indirect immunofluorescence staining using specific anti-receptor antibodies. These findings suggest that the expression of estrogen-inducible progestin receptors in cultured glial cells of the PNS is mediated via intracellular estrogen receptors and that it requires the presence of neuronal signal(s).
来自中枢神经系统（CNS）和外周神经系统（PNS）的大鼠神经胶质细胞表达类固醇激素受体。虽然中枢神经系统培养的神经胶质细胞中的孕激素受体（PR）是雌激素诱导型的，但在从新生大鼠坐骨神经制备的外周神经系统神经胶质细胞（雪旺细胞）培养物中，却未发现PR有类似的增加。在本研究中，我们使用胎儿背根神经节培养物来研究雌激素及其拮抗剂ICI 164,384对大鼠雪旺细胞中PR表达的影响。在从培养物中切除神经节后18小时，通过全细胞测定或细胞胞质溶胶中的激素结合来测量PR水平。用雌二醇（E2）处理背根神经节 - 雪旺细胞培养物，可使未处理细胞和雌激素处理细胞中的PR水平分别从约60 fmol/mg胞质溶胶蛋白增加到160 fmol/mg胞质溶胶蛋白。这种增加是剂量依赖性的；在50 nM E2浓度下可获得最大诱导效果。用拮抗剂ICI 164,384处理培养物可完全抑制雌激素对PR的诱导，而单独的ICI对雪旺细胞中的受体水平没有影响。PR的雌激素诱导作用取决于雌激素处理期间背根神经节的存在。从培养物中切除神经元团会导致雌激素诱导的孕激素受体迅速减少并消失，而非诱导性PR结合位点的浓度保持不变。雌二醇对背根神经节 - 雪旺细胞增殖没有影响，只有重新接种的第二代雪旺细胞在存在100 nM E2和5 microM福司可林时显示出略高的增殖水平。通过配体结合实验也在背根神经节 - 雪旺细胞中证实了雌激素受体（ER）。特异性ER结合为36±8 fmol结合雌二醇/mg胞质溶胶蛋白。最后，使用特异性抗受体抗体通过间接免疫荧光染色在雪旺细胞中观察到PR和ER。这些发现表明，外周神经系统培养的神经胶质细胞中雌激素诱导的孕激素受体的表达是通过细胞内雌激素受体介导的，并且需要神经元信号的存在。
