Ein isopropanolischer Extrakt der Traubensilber- kerze (iCR) stimuliert die Expression von Osteoprotegerin in primären humanen Osteoblasten

2- to 3-fold in a dose-dependent manner, with a maximum effect at a 106-fold dilution of iCR (p < 0.001) after 24-48 h. Time-course experiments indicated a stimulatory effect of iCR on osteoblastic OPG protein secretion by 3- to 5-fold (p < 0.001) as early as 12 h, whereas RANKL expression was very low and was not found to be modulated by iCR. Moreover, iCR enhanced two osteoblastic differentiation markers, bone-specific alkaline phosphatase activity and osteocalcin expression, by up to 4- and 3-fold, respectively (p < 0.001). Interestingly, the pure estrogen receptor antagonist ICI 182,780 abrogated the stimulatory effect of iCR on OPG production. This proposes estrogen receptor-mediated pathways for black cohosh and iCR could thus qualify as a tissue specific estrogen agonist and/or antagonist. Our data suggest that iCR enhances differentiation and increases the OPG-to-RANKL ratio of normal human osteoblasts. These effects may contribute to the positive skeletal effects of black cohosh.. J Menopause 2006; 13 (1): 18-21.