ObjectiveThe aim of this study was to explore the effects over time of lactic acid (LA) on IκBα phosphorylation and expressions of nuclear factor-kappa B p65 protein, tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) mRNA in the NF-κB signaling pathway in rat intestinal mucosal microvascular endothelial cells stimulated by lipopolysaccharide (LPS), and then to assess the optimal action time of LA and its regulating site in the NF-κB signaling pathways.MethodsIκBα, phosphorylated IκBα (p-IκBα) and NF-κB p65 proteins were monitored by Western blot analysis, and the TNF-α and IL-6 mRNA was analyzed using real-time PCR. ResultsLA treatment reduced TNF-α and IL-6 mRNA expression in LPS-stimulated RIMMVECs, with the greatest effect after 24 h and 3 h. The highest inhibitory effect of LA on IκBα phosphorylation and NF-κB transcriptional activity was during 4 to 8 h. The site of action of LA was IκBα phosphorylation in the signaling pathways. ConclusionsThe results of this study suggest that LA inhibits downstream inflammatory cytokine expression through inhibiting IκBα phosphorylation and blocking activation of NF-κB, thus playing a key anti-inflammatory role in the intestinal mucosal microvascular endothelial cells in rats.