AIM: Using two kinds of osteoblast like cell lines TE85 and U2 as cell models, the molecular mechanism of 17β estradiol
(E 2) in regulating cell function was studied. METHODS: Using methods of 3H thymidine incorporation for cell
proliferation, ELISA for IL 6 content measurement and transferring L 3H arginine to L 3H citruline for iNOS activity. RESULTS: In two cell lines,interleukin 1(IL 1, 20 U·mL -1 ) and tumor necrosis factor (TNFα 50 U·mL -1 ) stimulated osteoblast to secret IL 6 after treatment for 48 h. At the same concentration, IL 1 and TNFα reduced the
intracellular protein content resulting from cell proliferation inhibition. In TE85 cells, E 2 reduced the IL 6 secretion and inhibited the influence of IL 1 and TNFα on the cell proliferation. After L NMMA, an inhibitor of NOS, was added, the 3H TdR uptake decreased in a dose dependent fashion in TE85 and U2 cells. When the cells were treated with E 2 and L NMMA concomitantly, the inhibiting effects of the latter were diminished and the percentage of 3H TdR uptake reached normal levels. Besides that, IL 1 and TNFα increased intracellular iNOS activity significantly, which was higher than that of E 2. CONCLUSION: E 2 regulated cell function by way of reducing IL 6 secretion and improving iNOS activity.