Study of the inhibition of endotoxin-induced nitric oxide synthase gene expression by naphthoquinone and chalcone derivatives

• Main Authors: Wu, Jeng-Feng, 吳政峰
• Other Authors: Yu Sheu-Meei
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/73003607827447555712

碩士 === 長庚醫學暨工程學院 === 基礎醫學研究所 === 85 === Abstract We studied the effect of PPM-15, PPM-18 and 3,4,4'-HC, on thelipopolysaccharide (LPS)-stimulated inducible nitric oxide synthase(iNOS) expression in rat alveolar macrophages. Pretreatment of macrophages with PPM-15, PPM-18 or 3,4,4'-HC (0.03-10 ug/ml) significantly inhibited the nitrite production, iNOS proteinexpression, and iNOS mRNA accumulation. PPM-15 or PPM-18 did notdirectly affect the enzymatic activities of iNOS and other constitutiveNOS. In contrast, 3,4,4'-HC partially inhibited the enzymatic activitiesof nNOS but not iNOS and cNOS. LPS-induced increase of nuclear transcription factor-kB (NF-kB) p65 and p50 in nucleus was suppressedby PPM-15 or PPM-18 (3 ug/ ml), but not by 3,4,4'-HC. Moreover, electrophoretic mobility shift assays (EMSA) demonstrated that PPM-15PPM-18 or 3,4,4'-HC inhibited the NF-kB-DNA binding induced by LPS inthe whole cells but did not when added in the nualear extract, suggesting that PPM-15 or PPM-18 did not interfere directly with the binding of NF-kB to DNA and that some events had to be processed before NF- kB could bind DNA. Examination of the NF-kB showed that PPM-15 or PPM-18 stabilized the NF-kB inhibitor, IkB-alpha, by preventing its degradation from NF-kB. Therefore, the stabilizationof IkB-alpha might have contributed to the inhibition of NF-kB activation. Whereas, the mechanism that 3,4,4'-HC directly inhibited the NF-kB-DNA binding induced by LPS in the whole cells is still unknown. These results also indicate strongly that NF-kB is involvedin the production of NO upon stimulation by LPS. In the mice modelof sepsis, PPM-15, PPM-18 or 3,4,4'-HC can protect the mice against LPS-induced lethal toxicity. Thus, they may hold the potential forthe treatment of sepsis shock.