ESTROGEN MODULATION OF OSTEOBLASTIC CELL-TO-CELL COMMUNICATION

Two osteoblastic cell populations, calvarial and marrow stromal cells, were exposed to estrogen derivatives in vitro. The hormonal effect wa s monitored by following intracellular Ca+2 levels [Ca+2](i) and gap-j unction communication. We measured fast changes in intracellular Ca+2 levels in response, oi these cells, to the steroid hormones. The chang es were dose dependent revealing maximal activity at 100 pM by 17-beta -Estradiol and 1 nM by estradiol-CMO. Additionally, the effect of estr ogen, on functional coupling of the cells, was measured using fluoresc ence dye migration and counting the number of neighboring cells couple d by gap junctions. An uncoupling effect was demonstrated in response of these cells to estrogen treatment. The quick stereospecific effect was achieved in the presence of 17-beta-estradiol but not in the prese nce of 17-alpha-estradiol. These results suggest the involvement of pl asma membrane receptors in addition to the already known nuclear recep tors in transducing the hormone effects in the osteoblastic cells. (C) 1996 Wiley-Liss, Inc.