The change in Toll-like receptor 4 gene expression in skeleton of endotoxemia mice

Abstract

To explore the changes in gene expression of bone in endotoxemia in mice. 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, 12, 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. 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 normal level 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. Expression level of TLR4 mRNA in bone is significantly increased in endotoxemia mice.