Mechanisms of action of antiosteoporotic effects of a special Cimicifuga racemosa (CR) extract: Inhibition of the RANK-RANKL-Osteoprotegerin triad

Objective Receptor activator of nuclear factor κB (RANK), its ligand RANKL and the RANKL decoy receptor osteoprotegerin (OPG) form a protein triad of importance for maintenance of bone homeostasis. Estradiol-17β (E2), testosterone (T) and the Cimicifuga racemosa extract BNO 1055 (CR BNO 1055) have antiosteoporotic effects following gonadectomy of female or male rats. Their mechanisms of action, however, remain unexplored. Design Rats were ovariectomized (ovx) or orchidectomized (orx) and substituted with E2 (0.4mg/day/animal male and female), T (56.1mg/day/animal male) and CR BNO 1055 29.97mg/day/female animal a…