Buster B L, Weintrob A C, Townsend G C, Scheld W M
Department of Medicine, University of Virginia School of Medicine, Charlottesville 22908, USA.
Infect Immun. 1995 Oct;63(10):3835-9. doi: 10.1128/iai.63.10.3835-3839.1995.
We have investigated the possible role of nitric oxide (NO) in the pathophysiology of bacterial meningitis (BM) by using the rat model of experimental BM. The nitrite concentration in cerebrospinal fluid (CSF) was used as a measure of NO production in vivo since NO rapidly degrades to nitrite and nitrate. Rats were inoculated intracisternally with live bacteria (5 x 10(6) CFU of Haemophilus influenzae type b strain DL42 or Rd-/b+/O2), with bacterial endotoxin (20 ng of DL42 lipooligosaccharide [LOS] or 200 ng of Escherichia coli lipopolysaccharide), or with a saline control vehicle. CSF samples were collected preinoculation and at the time of maximal alteration in blood-brain barrier permeability (BBBP). CSF [nitrite] was quantified by measuring A550 after addition of the Greiss reagent and comparison to a standard curve of sodium nitrite. Rats inoculated with either DL42, Rd-/b+/O2, LOS, or lipopolysaccharide demonstrated a significantly elevated mean peak CSF [nitrite] (8.34, 15.62, 10.75, and 10.44 mM, respectively) versus the concentration prior to treatment and/or those in saline-treated animals (5.29 and 5.33 mM, respectively; P < 0.05 for each comparison). We then determined if there was a correlation between CSF [nitrite] and percent BBBP (%BBBP) at various time points postinoculation with Rd-/b+/O2. %BBBP was defined as the concentration of systemically administered 125I-labeled bovine serum albumin in the CSF divided by the level of 125I-labeled bovine serum albumin in serum multiplied by 100. The mean %BBBP increased in tandem with the mean CSF [nitrite] (R = 0.84, P = 0.018), which peaked at 18 h in the absence of a change in the serum [nitrite]. Systemic administration of the NO synthase inhibitor N-nitro-L-arginine methyl ester demonstrated a significant reduction of mean CSF nitrite production (0.95 versus 6.0 mM in controls; P = 0.02) when administered intravenously to animals which had been inoculated intracisternally with 20 ng of LOS. Suppression of mean leukocyte pleocytosis (3,117 versus 11,590 leukocytes per mm3 in control LOS-challenged rats; P = 0.03) and mean alterations of BBBP (2.11 versus 6.49% in control LOS-challenged rats; P = 0.009) was observed concomitantly with decreased CSF [nitrite]. These results support the hypothesis that NO contributes to increased %BBBP in experimental BM.
我们通过使用实验性细菌性脑膜炎（BM）大鼠模型，研究了一氧化氮（NO）在细菌性脑膜炎病理生理学中的可能作用。由于NO会迅速降解为亚硝酸盐和硝酸盐，因此脑脊液（CSF）中的亚硝酸盐浓度被用作体内NO生成的指标。大鼠经脑池内接种活细菌（5×10⁶CFU的b型流感嗜血杆菌DL42株或Rd⁻/b⁺/O2株）、细菌内毒素（20 ng的DL42脂寡糖[LOS]或200 ng的大肠杆菌脂多糖）或生理盐水对照剂。在接种前以及血脑屏障通透性（BBBP）发生最大改变时采集脑脊液样本。通过加入格里斯试剂后测量A550并与亚硝酸钠标准曲线进行比较来定量脑脊液[亚硝酸盐]。接种DL42、Rd⁻/b⁺/O2、LOS或脂多糖的大鼠与治疗前浓度和/或生理盐水处理动物的浓度相比，平均脑脊液[亚硝酸盐]峰值显著升高（分别为8.34、15.62、10.75和10.44 mM）（分别为5.29和5.33 mM；每次比较P<0.05）。然后我们确定在接种Rd⁻/b⁺/O2后的不同时间点，脑脊液[亚硝酸盐]与BBBP百分比（%BBBP）之间是否存在相关性。%BBBP定义为脑脊液中全身给药的¹²⁵I标记牛血清白蛋白浓度除以血清中¹²⁵I标记牛血清白蛋白水平再乘以100。平均%BBBP与平均脑脊液[亚硝酸盐]同步增加（R = 0.84，P = 0.0（此处原文有误，推测应为0.018）），在血清[亚硝酸盐]无变化的情况下，于18小时达到峰值。对经脑池内接种20 ng LOS的动物静脉注射NO合酶抑制剂N-硝基-L-精氨酸甲酯后，脑脊液亚硝酸盐平均生成量显著降低（对照组为6.0 mM，处理组为0.95 mM；P = 0.02）。同时观察到平均白细胞增多症受到抑制（对照LOS攻击大鼠每立方毫米有11590个白细胞，处理组为3117个；P = 0.03）以及BBBP的平均改变受到抑制（对照LOS攻击大鼠为6.49%，处理组为2.11%；P = 0.009），同时脑脊液[亚硝酸盐]降低。这些结果支持了NO导致实验性BM中%BBBP增加的假说。
