Influence of raloxifene on expression of TNF-α in cancellous bone and bone mineral density in ovariectomized rats

AIM: To discuss the influence of selective estrogen receptor modulator(SERM) raloxifene(RAL) on the expression of TNF-α in cancellous bone and bone mineral density (BMD) loss in ovariectomized rats. METHODS: Thirty 8-month nulliparous female SD rats were divided into 3 groups(10 rats per group):sham operation (SHAM)group, ovariectomized (OVX)group and therapeutic (OVX+ RAL)group. Bilateral ovariectomies were done on OVX group and OVX+ RAL group. Sham operation was performed on SHAM group. OVX+ RAL group was treated with RAL 2 d after operation. Twenty weeks after operation, all rats were sacrificed.BMD of L3-L5 vertebrae, proximal femoral segment, femoral body were measured by dual energy X-ray absorptiometry(DEXA). SABC immunohistochemistry and image analysis were used to detect the expression of TNF-α in L2 vertebral bone of every group. RESULTS: ① The gray scale of TNF-α in cancellous bone in OVX group was lower than that in SHAM group (P0.01), and also lower than that in OVX+ RAL group (P0.01), indicating that the expression of TNF-α in cancellous bone in OVX group increased after ovariectomy, and became weak after RAL treatment. ② Twenty weeks after ovariectomy, BMD of L3-L5 vertebrae, proximal femoral segment, femoral body of ovariectomized rats decreased significantly and the trabecular bone became thinner and irregular as compared with SHAM group(P0.01). After treatment of RAL, the above parameters were maintained close to the level of SHAM group (P0.05). CONCLUSION: RAL could inhibit the expression of TNF-α in cancellous bone of ovariectomized rats and depress the occurrence of osteoporosis in ovariectomized rats.