Abstract: Objective To explore the changes in gene expression of bone in endotoxemia in mice.Methods Lipopolysaccharide(LPS)was injected intraperitoneally to reproduce an endotoxemia model in mice.Forty-eight mice were randomly divided into eight groups:normal group,4,6,8,1 2,24,48 and 72 hours after LPS injection groups,with 6 mice in each group.To evaluate endotoxemia whole blood was collected for leukocytic count,eye sockets blood was obtained for liver and renal functions tests.mRNA expression level of Toll-like receptor 4(TLR4)in bone was determined by reverse transcription-polymerase chain reaction(RT-PCR)assay.The pathological changes of bone and tissue slides were prepared with hematoxylin and eosin(HE)staining for observing under microscope.Results Compared with normal group,leukocyte count of 4-hour LPS-treated group was significantly decreased(P<0.01).However.after 4 hours,leukocyte count became higher gradually and remained at high level at 72 hours compared with that of normal group(P<0.05).Compared with normal group,alanine aminotransferase(ALT)level reached to a high level in LPS-treated groups at 4 hours and 6 hours(both P<0.05),and then decreased gradually showing a tendency to return to normal level after 8 hours(P>0.05).Blood urea nitrogen(BUN) was increased at 6 hours(P<0.05),reaching to the highest level at 8 hours(P<0.05)and tended to become normallevel after 12 hours(P>0.05).Six hours after LPS treatment,the expression of TLR4 mRNA was enhanced(P<0.01)and reached the peak at 24 hours(P<0.01),and it remained at a high level at 72 hours (P<0.05).However,there were no significant pathological changes in bone structure after LPS treatment.