Abstract: To investigate the effects of Rhizome Drynariae on bone microarchitecture of ovariectomized rats and to explore its possible mechanisms. Thirty-six rats were divided into experimental group (OVXDF), model group (OVX), and sham operation group (SHAM). In the OVXDF and OVX groups, bilateral ovaries were removed. Eight weeks after operation, bone mineral density was measured. After this, the OVXDF group was administered Rhizoma Drynariae intragastrically, and the OVX and SHAM groups received normal saline intragastrically for 12 weeks. Subsequently, micro-CT was used to measure bone mineral density (g/cm³), bone mineral content (g), trabecular bone volume over total volume (%), and trabecular thickness Tb.Th(μm), trabecular bone number Tb.N(mm^-1), trabecular bone separation degree Tb.sp (mm), and structural model index. Rat microscopic morphology of the bone tissue was observed under microscope. Concentrations of tartrateresistant acid phosphatase, matrix metallopeptidase 9, and CTX-1 in rat serum were measured by enzyme-linked immunosorbent assay. The experiment results showed not only decreased bone mass but also changed bone microarchitecture in ovariectomized rats. Rhizoma Drynariae decocted with water intragastrically can effectively compensate for the decrease in bone mineral density and the change in bone microarchitecture in ovariectomized rats. Its mechanism of action is associated with its inhibition of bone marrow adipocyte formation and suppression of activity and number of osteoclasts.

Key words: postmenopausal osteoporosis, Rhizome Drynariae, Micro-CT, adipocyte, bone microarchitecture