[The pattern of nuclear factor-kappaB activation in rats with endotoxin shock and its role in biopterin-mediated nitric oxide induction].

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.