OVARIECTOMY AND ORCHIECTOMY INDUCE A TRANSIENT INCREASE IN THE OSTEOCLASTOGENIC POTENTIAL OF BONE-MARROW CELLS IN THE MOUSE

Withdrawal of gender steroids in both women and men is associated with an increase in bone turnover with bone resorption exceeding bone form ation leading to bone loss. To further investigate this process, the o steoclastogenic potential of mouse bone marrow cells was assessed at d ifferent time-points after ovariectomy (ovx) or orchidectomy (orx). Co cultures of osteoclast-free fetal mouse long bones together with bone marrow form ovariectomized or orchidectomized mice indicated that the withdrawal of gender steroids in female and male mice induces a transi ent increase in osteoclastogenesis. The osteoclastogenic potential of the bone marrow cells was increased 7 days after ovx or orx. However, osteoclastic resorption was not increased at 3 days after surgery and had normalized 30 days after either ovx or orx. These results suggest that the withdrawal of gender steroids induces a transient increase in osteoclastogenesis in mice of both genders, which is associated with the early phase of rapid bone loss.