LPS induces significant bone loss and decreases bone mineral density (BMD), bone volume (BV/TV), and trabecular thickness (Tb. Th) compared with PBS alone, whereas trabecular space (Tb. Sp.) is increased. Sodium 4-phenylbutyrate (Sodium phenylbutyrate) attenuates LPS-induced bone loss. Treatment with Sodium 4-phenylbutyrate increases BMD, BV/TV, and Tb. Th. compared with LPS alone, in addition to decreasing the enlargement of Tb. Sp., but no change is observed when mice are treated with Sodium 4-phenylbutyrate alone. OC.S/BS as assessed by TRAP staining is also significantly reduced when Sodium 4-phenylbutyrate is administered to LPS-treated mice. However, OC.N/BS tends to decrease, although not with statistical significance, when mice are treated with Sodium 4-phenylbutyrate and LPS. These results indicate that the effect of Sodium 4-phenylbutyrate on OC from LPS-treated mice is to reduce its size rather than number. Consistent with these findings, a marker of bone resorption in vivo, serum CTX-1 which is elevated by LPS treatment is decreased when Sodium 4-phenylbutyrate administered to LPS-injected mice. However, co-treatment with Sodium 4-phenylbutyrate do not significantly affect the levels of serum ALP and osteocalcin, 2 markers of bone formation in vivo, compared with LPS alone. Sodium 4-phenylbutyrate also reduces the LPS-induced rise in serum MCP-1, indicating that Sodium 4-phenylbutyrate decreases systemic inflammation induced by LPS.