C₂-ceramide inhibits LPS-induced nitric oxide production in RAW 264.7 macrophage cells through down-regulating the activation of Akt

The effect of C₂-ceramide, a membrane-permeable ceramide analogue, on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells was studied. The non-toxic concentration of C₂-ceramide inhibited LPS-induced NO production. It was due to the attenuated expression of the inducible type of NO synthase (iNOS). C₂-ceramide did not influence the phosphorylation of a series of mitogen-activated protein (MAP) kinases in response to LPS. On the other hand, C₂-ceramide down-regulated the phosphorylation of Akt in LPS-stimulated RAW 264.7 cells, followed by the impairment of nuclear factor (NF)-κB activation. Moreover, the Akt dominant-negative mutant inhibited LPS-induced NO production. C₂-ceramide was suggested to inhibit LPS-induced NO production through down-regulating the activation of Akt.