Objective To investigate the effects of tumor necrosis factor alpha（TNF-α） on the growth of rat osteoblasts. To find out the mechanisms that TNF-α regulates the growth of osteoblasts. Methods To assay osteoblasts proliferation by MTT. To assay alkaline phosphatase（ALP） activity of osteoblasts by PP-nitrophenyl phosphate（PNPP）. Results The osteblasts proliferation and the ALP activity decreased in treatment groups, and the significantly lower levels were observed in above 50 ng/mL groups（P＜0.05）. Conclusion TNF-α restrained osteoblasts proliferation and differentiation, and the effects were more significant in above 50 ng/mL groups.
