HUMAN RAMIFIED MICROGLIAL CELLS PRODUCE NITRIC-OXIDE UPON ESCHERICHIA-COLI LIPOPOLYSACCHARIDE AND TUMOR-NECROSIS-FACTOR-ALPHA STIMULATION

This study shows that human ramified microglial cells derived from fetal brain primary cultures, are able to produce nitric oxide (NO). In fact, stimulation with Escherichia coli lipopolysaccharide (LPS) (1 mu g ml(-1)) or tumor necrosis factor alpha (TNF alpha) (500 U ml(-1)) enhances nitrite release in cell supernatants, as determined by the Griess reaction. A synergistic effect is achieved following treatment with LPS plus TNF alpha, this effect being inhibited by pretreating cells with NOS inhibitor NW-nitro-L-arginine methyl ester (L-NAME). Using reverse transcriptase-polymerase chain reaction (RT-PCR) acid Southern. blot analysis, we also found that LPS/TNF alpha produce an increase of inducible NO synthase (iNOS) mRNA expression.