The roles of neurons on the nitric oxide production of microglia stimulated by LPS and IFN-γ = LPS/IFN-γ에 의해 活性化된 microglia NO 生成에 있어서의 neuron의 役割

다국어 초록 (Multilingual Abstract)

Activation of glial cells often occurs at neuronal injury or death. But interaction between neuronal cells and microglia on the production of nitric oxide (NO) are not fully understood. This study aimed to elucidate whether neurons is important in modulating the production of NO in microglia stimulated by the lipopolysaccharide (LPS) and interferon-γ (IFN-γ). When PC12 cells were cocultured with microglia through direct or indirect contact, PC12 cells enhanced nitrite production in particularly LPS and IFN-γ-stimulated microglia. The NO production was decreased by a neutralizing anti-neural cell adhesion molecule (NCAM) and anti-tumor necrosis factor alpha (TNF-α) antibodies in LPS and IFN-γ-treated coculture, while neuraminidase, MMP-1 inhibitor had no effects on the cells. When TNF-α was added to PC12 cells or microglia in absence or presence of LPS and IFN-γ, results of immunoblotting and RT-PCR showed that levels of iNOS mRNA and iNOS expression were upregulated. But, level of TNF-α mRNA made no difference in untreated or treated cells. The PC12-conditioned medium (PC12CM) enhanced the nitrite production in microglia treated with LPS and IFN-γ. Blockade of the MAP kinase signal transduction pathway with either PD98059 (an inhibitor of ERK kinase) or SP203580 (an inhibitor of p38 kinase) did not inhibit the action of PC12CM. However, TPCK (an inhibitor of NF_-k B) decreased the effect of PC12CM in dose-dependent manner. These results suggest that PC12 cells induce nitrite production in microglia treated with LPS and IFN_-γ through release of soluble factors. And the soluble factors are postulated to be TNF_-α or NCAM.