生物喋呤合成酶抑制剂对烫伤大鼠金葡菌脓毒症的保护效应及机制

目的　探讨生物喋呤合成限速酶抑制剂 - 2 ,4 二胺 6 羟基嘧啶 (DAHP)对金黄色葡萄球菌 (简称金葡菌 )脓毒症的保护效应及机制。　方法　 5 6只Wistar大鼠随机分为正常对照组、2 0 %TBSAⅢ度烫伤对照组、烫伤后金葡菌感染组和DAHP拮抗组。无菌留取大鼠心、肝、肺、肾组织检测三磷酸鸟苷环水解酶I(GTP CHI)、诱生型一氧化氮合酶 (iNOS)及肿瘤坏死因子α (TNFα )基因表达 ,同时测定组织中四氢生物喋呤 (BH4)和一氧化氮 (NO)的水平。　结果　烫伤后金葡菌感染可导致组织GTP CHI基因表达广泛上调、BH4合成显著增加。同时 ,组织iNOSmRNA表达和NO水平亦明显升高 ,其中肝、肺改变尤为显著。给予DAHP不仅可显著抑制各组织GTP CHImRNA表达和BH4的产生 (P<0 .0 5～ 0 .0 1) ,iNOSmRNA表达和NO的生成亦明显受抑 ,同时TNFα表达也明显降低。此外 ,DAHP拮抗组动物 6h死亡率有所降低 (分别为 2 5 .0 %和 5 5 .6 % ,P =0 .0 8)。　结论　DAHP早期干预可在一定程度上改善革兰阳性菌脓毒症动物的预后 ,其机制可能与DAHP抑制体内BH4和NO的产生有关。

The protective effect and its underlying mechanism of 2,4-diamino-6-hydroxy-pyrimidine on postburn Staphylococcus aureus sepsis in rats

OBJECTIVE: To investigate the protective effect and its underlying mechanism of 2,4-diamino-6-hydroxy-pyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I (GTP-CHI), on postburn Staphylococcus aureus (S. aureus) sepsis in rats. METHODS: Fifty-six Wistar rats were randomly divided into four groups, i.e. normal control, scalding control, postburn sepsis group and DAHP treatment group. Tissue samples from liver, kidneys, lungs and heart were aseptically taken, and in which the GTP-CHI and inducible nitric oxide synthase (iNOS) contents and the mRNA expression of tumor necrosis factor-alpha (TNFalpha) were determined. Furthermore, biopterin (BH(4)) and nitric oxide (NO) levels in these tissue were also measured. RESULTS: After the scalding injury followed by bacterial challenge, the GTP-CHI gene expression and biopterin levels were significantly increased in all tissue sampled, and so were iNOS mRNA expression and NO (P < 0.01), especially in liver and lungs. The expressions of GTP-CHI mRNA and iNOS mRNA and the production of BH(4) and NO in all tissue were evidently inhibited by the pretreatment with DAHP (P < 0.05 approximately 0.01). At the same time, the TNFalpha expression was also obviously decreased. In addition, The mortality at 6 hr in rats of DAHP treatment group was decreased. CONCLUSION: The prognosis of the scalding rats complicated by sepsis caused by G(+) bacteria could be improved by DAHP pretreatment, which might be related to the inhibition of the production of BH(4) and NO by DAHP.