OBJECTIVETo explore the influence of lanthanum chloride (LaCl3) on inducible nitric oxide synthase (iNOS) expression in RAW264.7 macrophages with lipopolysaccharide (LPS) induction, and to investigate its possible mechanisms.

METHODSThe RAW264.7 macrophages were randomly divided into four groups: i. e, control group (without treatment), LaCl3 group (with treatment of 2.5 micromol/L of LaCl3 for 24 hrs), LaCl3 + LPS group (with treatment of 2.5 micromol/L LaCl3 for 24h), and LPS group (with treatment of 1 mg/L LPS for 24 hrs). The iNOS protein expression was measured by immunofluorescence and Western blot. iNOS gene expression was assayed by reverse transcription-polymerase chain reaction (RT-PCR). NO production in culture supernatant was assayed by nitrate reductase method.

RESULTSImmunofluorescence analysis showed that iNOS was located mainly in the cytoplasm. RAW264.7 cells with overexpression of iNOS accounted for 44.4%, which was obviously higher than that in LaCl3 + LPS group (11.8%, P < 0.05). There was a faint signal of FITC-labeled green tint in control group or LaCl3 group. The iNOS mRNA and protein expression, and the NO content in LPS group were significantly higher than those in control, LaCl3, and LaCl3 + LPS groups (P < 0.05).

CONCLUSIONLaCl3 can suppress LPS-induced iNOS overexpression at mRNA and protein level and reduce NO production, indicating that LaCl3 can antagonize the excessive activation of iNOS induced by LPS.