| Objective To investigate whether there are differences in the bone mass and microstructure of the lumbar vertebrae in different regions of osteoporosis rats induced by ovariectomy (OVX) based on micro-CT. Methods Thirty female SD rats were randomly divided into basic group, Sham group, and OVX group. The 5th lumbar vertebrae were taken on the day of surgery, 3 months (3M) after surgery, and 6 months (6M) after surgery. Micro-CT was used to analyze the bone mass and microstructure changes in the distal, middle, proximal, and whole regions. Results ①Dynamic changes in bone microstructure of rats in each group: BMD and BV/TV in all regions (except for the 3M proximal region) of Sham group rats increased significantly over time (P<0.01, P<0.05), Tb.Th in the distal, proximal, and whole regions increased significantly over time (P<0.01), and Tb.N in the middle region increased significantly (P<0.05). In OVX rats at 3M and 6M, BMD and BV/TV significantly decreased over time in all regions (except for the 3M proximal region, P<0.01, P<0.05). Rats of OVX 3M showed a significant decrease in Tb.N in all regions compared to those in the basic group (P<0.01, P<0.05). Tb.SP in the distal, middle, and whole regions increased significantly (P<0.01, P<0.05). Rats of OVX 6M showed a significant decrease in Tb.Th in the middle region, compared to those in the basic group (P<0.05), a significant decrease in Tb.N in each region (P<0.01), and a significant increase in Tb.Sp (P<0.01, P<0.05). ②Sensitivity analysis of bone microstructure changes in OVX rats: In rats of OVX 3M, except for the proximal region, BMD and BV/TV in the other three regions reduced significantly compared to those in the Sham group (P<0.01). Tb.Th of OVX rats in the distal and whole regions reduced significantly compared to those in the Sham group (P<0.05). Tb.N of OVX rats in the distal, middle, and whole regions reduced significantly (P<0.01) and Tb.Sp significantly increased (P<0.01, P<0.05). In rats of OVX 6M, BMD and BV/TV in all regions reduced significantly compared to those in the Sham group (P<0.01). Tb.Th and Tb.N in OVX rats in all four regions reduced significantly compared to those in the Sham group (P<0.05, P<0.01). Tb.Sp increased significantly (P<0.01). Conclusion At different stages of osteoporosis, the trend of bone mass and bone microstructure changes is the same in different regions, but the sensitivity of each indicator change is different. In the later stages of osteoporosis, each region can be set as the analysis area. However, in the early stage, it is more appropriate to choose the distal region or the overall region. Considering factors such as the difficulty of analyzing operational methods, it is recommended to choose the distal region as the analysis area for osteoporosis rats induced by OVX. |