The pattern of nuclear factor-kappaB activation in rats with endotoxin shock and its role in biopterin-mediated nitric oxide induction / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the pattern of nuclear factor-kappaB (NF-kappaB) activation in rats with lipopolysaccharide( LPS) shock, and to explore the mechanism of NF-kappaB signal pathway in the biopterin-mediated nitric oxide(NO) induction, as well as its role in the development of multiple organ dysfunction syndrome ( MODS) secondary to endotoxin challenge.</p><p><b>METHODS</b>Fourty-seven male Wistar rats were randomly divided into control group ( C, n = 8) , LPS group ( n = 24, with 8 rats at each time-points, and shock model was made by injection of same dosage of LPS) , and pyrrolidine dithiocarbamate (PDTC) treatment group ( PDTC, n = 15, with 5 rats at each time-points, and the rats were injected with LPS and PDTC). The rats were sacrificed at 2,6,12 post-injection hour( PIH) , and the blood and tissue samples from liver, lungs and kidneys were harvested for the determination of NF-KB activity, GTP cyclohydrolase I (GTP-CH I ) , and inducible nitric oxide synthase (iNOS) mRNA expression in the liver, lungs and kidneys, plasma and tissue content of biopterin and NO, as well as hepatic and renal function, and pulmonary myeloperoxidase activity.</p><p><b>RESULTS</b>NF-kappaB DNA binding activity in LPS group was rapidly enhanced in liver, lungs and kidneys after endotoxin challenge when compared with that in controls (e. g. in pulmonary tissue it was 26+/-6) , and it reached the peak at 2 PIH, which was 291 +/-44 in pulmonary tissue( P <0. 01). GTP-CH I mRNA expression and biopterin levels in the liver, lung and kidney of each group were obviously higher than those in control group( P <0.05 or 0.01) , and it maintained at high levels at 12 PIH. Additionally, different degrees of dysfunction of the above mentioned organs was observed. Treatment with PDTC, an inhibitor of NF-KB signal transduction pathway, could reduce NF-kappaB DNA binding activity, inhibit GTP-CH I and iNOS/NO mRNA expression, as well as BH4, and NO levels in various tissues. Meanwhile the multiple organ damage was significantly ameliorated by PDTC pretreatment.</p><p><b>CONCLUSION</b>Endotoxin challenge can rapidly lead to activation of NF-kappaB in various tissues, and NF-KB pathway might markedly up-regulate the production of biopterin/NO following endotoxic shock. Inhibition of NF-kappaB pathway attenuates inflammatory response and ameliorates multiple organ dysfunction, which might be associated with its down-regulation of the excessive activation of iNOS mediated by biopterin.</p>

The mechanisms of extracellular-signal regulated protein kinase pathway in biopterin induction in rats with endotoxic shock / 中华外科杂志

<p><b>OBJECTIVE</b>To observe the influence of treatment with the inhibitor of extracellular-signal regulated protein kinase (ERK) signal transduction pathway on the expression of biopterin/nitric oxide (NO) as well as the activation of nuclear factor-kappaB (NF-kappaB), and to clarify the potential cross-talk regulation mechanisms between ERK and NF-kappaB pathway in biopterin-mediated NO induction in rats with endotoxic shock.</p><p><b>METHODS</b>Using an endotoxic shock model, 60 male Wistar rats were randomly divided into normal controls (n = 8), endotoxic shock group (n = 32) and PD98059 treatment group (n = 20). At serial time points animals in each group were sacrificed, and tissue samples from liver, lungs as well as kidneys were harvested to detect NF-kappaB activity, guanosine triphosphate-cyclohydrolase (GTP-CHI) and inducible nitric oxide synthase (iNOS) mRNA expression. Biopterin and NO levels in plasma and tissues were also assayed.</p><p><b>RESULTS</b>It was found that after lipopolysaccharide (LPS) challenge, GTP-CHI mRNA expression and biopterin levels significantly elevated in liver, lungs and kidneys, keeping at high values up to 24 h, so did the values of iNOS mRNA expression and NO levels. NF-kappaB DNA binding activity was enhanced rapidly in various tissues, peaking at 2 h after LPS challenge. Treatment with PD98059, an inhibitor of ERK signal transduction pathway, could significantly inhibit GTP-CHI mRNA expression in kidneys, and GTP-CHI mRNA expression in liver and lungs showed certain down-regulation tendency. At the same time, biopterin level was significantly decreased in plasma, liver and kidneys at 12 h. Similarly, iNOS/NO induction at early stage markedly decreased in various tissues. In addition, treatment with PD98059 reduced NF-kappaB DNA binding activity in liver, lungs, as well as kidneys at 2-6 h, 2 h, 24 h and 24 h after LPS challenge, respectively.</p><p><b>CONCLUSIONS</b>Inhibition of ERK pathway could partially inhibit the production of biopterin/NO as well as the activation of NF-kappaB pathway, which indicated that cross-talk regulation seems to be existed between ERK and NF-kappaB pathway, and they might be involved in the regulatory process of biopterin-mediated nitric oxide induction in rats with endotoxic shock.</p>