内毒素休克大鼠组织生物喋呤与高迁移率族蛋白B1表达的关系

The relationship between biopterin formation and tissue high mobility group box-1 protein expression in rats with endotoxic shock

目的 探讨生物喋呤 (BH4)对内毒素休克大鼠肝、肺、肾等多器官高迁移率族蛋白B1(HMGB1 )基因表达的影响及其可能机制。方法 采用内毒素休克模型 ,1 0 4只大鼠随机分为正常对照组(n =8)、内毒素休克组 (n =4 8)和BH4合成抑制剂— 2 ,4 二胺 6 羟基嘧啶 (DAHP)拮抗组 (n =4 8)。分别测定血浆BH4含量和肝、肺、肾组织HMGB1mRNA的表达水平。结果 与正常对照组比较 ,内毒素攻击后 2～ 2 4h大鼠血浆BH4含量显著升高 (P <0 0 1 )。同时 ,内毒素攻击后 2～ 6h大鼠肝、肺、肾组织HMGB1mRNA表达显著增强 ,并于 1 2～ 2 4h达峰值 (P <0 0 1 ) ,4 8h仍持续于较高水平。给予DAHP处理后 ,血浆BH4含量在 2、 6、 1 2h显著低于内毒素休克组 (P <0 0 5 ) ;动物肝、肾组织中HMGB1mRNA表达亦明显下调 (P <0 0 5 ) ,各时间点其水平均接近正常对照范围 :与内毒素休克组相比 ,DAHP组肺组织HMGB1mRNA表达峰值显著下降 (P <0 0 5 )。结论 生物喋呤对机体HMGBl的基因表达具有显著影响 ,它参与了内毒素休克时多种组织“晚期”

Objective To investigate the effect of biopterin formation on tissue high mobility group box 1 protein (HMGB1) gene expression in rats with endotoxic shock and its potential regulating mechanisms.Methods A rat model of endotoxic shock was reproduced by a bolus injection of lipopolysaccharide (10 mg/kg,i.v.). 104 male Wistar rats were randomly divided into normal controls ( n =8),endotoxic shock group( n =48), and 2,4 diamino 6 hydroxy pyrimidine (DAHP)treatment group( n =48). At serial time points animals in each group were sacrificed,plasma samples and tissue specimens from liver, lungs as well as kidneys were harvested. Plasma biopterin contents were measured by reverse phase high performance liquld chromatography/fluorescence detection. HMGB1 mRNA expression was semi quantitatively determined by reverse transcription polymerase chain reaction (RT PCR).Results Compared to normal controls, plasma biopterin contents were markedly elevated from 2 to 24 h after endotoxin challenge ( P <0 01).Concomitantly, HMGB1 mRNA levels were significantly increased in liver, lungs and kidneys at 2 to 6 h after endotoxin challenge, respectively, peaking at 12 to 24 h ( P <0 05), and keeping high values up to 48 h. Treatment with DAHP, an inhibitor of tetrahydrobiopterin synthesis, could significantly reduce plasma biopterin contents at 2,6,and 12 h in rats following lipopolysaccharide challenge ( P <0 05).Similarly, hepatic and renal HMGB1 mRNA expressions in DAHP treatment group were evidently down regulated compared with endotoxic shock group at various intervals ( P <0 05),and close to normal range( P > 05).In addition, DAHP markedly decreased pulmonary HMGB1 mRNA expression at 12 h after endotoxic shock ( P <0 05). Conclusion These data suggested that biopterin formation had significant effect on HMGB1 mRNA expression, and it might be involved in the regulation of delayed mediator--HMGB1 synthesis,as well as its release in vital organs secondary to endotoxic shock.