Abstract: ObjectiveTo explore the mechanism of estrogen inhibiting osteoblast apoptosis induced with serum hungry.MethodsOsteoblasts of the second or third generation from newly born SD rats calvaria were divided randomly into three groups: control group,serum hungry group,serum hungry with estrogen group.Cells of each group were incubated for 1,2,3,5,7 or 14 d,and then were stained immunohistochemically.The rates of positive cells of each group were analyzed.ResultsThere was a little positive expression of Bax,Bcl2 and Fas in control group.The expression of Bax and Fas were significantly increased(P<0.05)in serum hungry group,peak time was 14 d,but the expression of Bcl-2 were not affected.Compared with that of serum hungry group,the expression of Bax and Fas significantly decreased(P<0.05) in serum hungry and estrogen group,peak time was still 14 d,while that of Bcl-2 increased(P<0.05).ConclusionSerum hungry can increase the expression of Bax and Fas in osteoblast,that can be inhibited by estrogen.Estrogen can also increase the expression of Bcl-2 in osteoblast.All of these may play a role in inhibiting osteoblast apoptosis induced with serum hungry.

Key words: estrogen, osteoblast, apoptosis, gene