Ovariectomy and orchidectomy 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 formation leading to bone loss. To further investigate this process, the osteoclastogenic potential of mouse bone marrow cells was assessed at different timepoints after ovariectomy (ovx) or orchidectomy (orx). Cocultures of osteoclast-free fetal mouse long bones together with bone marrow from ovariectomized or orchidectomized mice indicated that the withdrawal of gender steroids in female and male mice induces a transient 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.