A study on the relationship between the changes of CBG levels and the incidence of bone marrow necrosis in the femoral head after hormone administration in young rats

Objective To construct an osteonecrosis of the femoral head model in young rats, and to investigate the relationship between the changes of corticostroid-binding globulin (CBG) and femoral head necrosis. Methods A total of 108 SD young rats were randomly divided into three groups (n=36). A blank group was intraperitoneally injected with 1.5 mg/kg of normal saline once daily for a week. A low-dose group was intraperitoneally injected with 1.5 mg/kg dexamethasone sodium phosphate once daily for a week, while a high-dose group was intraperitoneally injected with 3.0 mg/kg dexamethasone sodium phosphate once daily for one week. Three rats were randomly selected from each group on Day 0, 3, and Weeks 1, 2, 3 and 4 after injection to take blood from the orbital venous plexus of the eye. The level of CBG was measured by Western blotting. After the rats were sacrificed, their femoral heads were removed to make pathological sections and observe adipocyte area ratio and bone empty lacuna rate. Results Compared with the normal rats, rats after one week of hormone stimulation showed a reduced number of hematopoietic cells in the bone marrow and an increased number of adipocytes in the femoral head sections. Difference was found between the blank and experimental groups. The expression was relatively consistent between allogeneic individuals. After injection for 1, 2 and 3 weeks, the levels of blood CBG was increased in the low-dose and high-dose groups, which were slightly decreased at Week 4 after injection. For the pathological sections, except for Day 0 group, the ratio of adipocyte area was slightly higher in other groups than that in the blank group, and gradually decreased on Weeks 3 and 4. (P<0.05). Conpared with the low-dose group, the rate of empty bone lacuna in high-dose group on Weeks 1, 2 and 4 was slightly increased (P>0.05). Conclusions Administration of dexamethasone sodium phosphate can increase the rate of bone empty lacuna in the femoral head, and the ratio of adipocyte area reaches the peak on about Week 2. The expression of CBG is associated with the increase of bone empty lacuna rate.