Serum myoglobin,but not lipopolysaccharides,is predictive of AMPH-induced striatal neurotoxicity

Determinants of amphetamine (AMPH)-induced neurotoxicity are poorly understood. The role of lipopolysaccharides (LPS) and organ injury in AMPH-induced neurotoxicity was examined in adult male Sprague-Dawley rats that were give AMPH and became hyperthermic during the exposure. Environmentally-induced hyperthermia (EIH) in the rat was compared to AMPH to determine whether AMPH-induced increases in LPS and peripheral toxicities were solely attributable to hyperthermia. Muscle, liver, and kidney function were determined biochemically at 3 h or 1 day after AMPH or EIH exposure and histopathology at 1 day after treatment. Circulating levels of LPS were monitored (via limulus amoebocyte coagulation assay) during AMPH or EIH exposure. Blood LPS levels were detected in 40–50% of the AMPH and EIH rats, but the presence of LPS in the serum had no effect on organ damage or striatal dopamine depletions (neurotoxicity). In both CR and NCTR rats, serum bound urea nitrogen and creatinine levels increased at 3 h after EIH or AMPH (2- to 3-fold above control) but subsided by 1 day. Alanine transaminase was increased (indicating liver dysfunction) by both AMPH and EIH at 3 h (2- to 10-fold above control) in CR rats, but the levels were not significantly different between the control and AMPH groups in NCTR animals. Mild liver necrosis was detected in 1 of 7 rats examined in the AMPH group and in 1 of 5 rats examined in the EIH group (only NCTR rats were examined). Serum myoglobin increased (indicating muscle damage) in both CR and NCTR rats at 3 h and was more pronounced with AMPH (≈5-fold above control) than EIH. Our results indicate that: (1) “free” blood borne LPS often increases with EIH and AMPH but may not be necessary for striatal neurotoxicity and CNS immune responses; (2) liver or kidney dysfunction may result from muscle damage; however, it is not sufficient nor necessary to produce, but may exacerbate, neurotoxicity; (3) AMPH-induced serum myoglobin release is a potential biomarker and possibly a factor in AMPH-induced toxicity processes.     

Lidocaine attenuates lipopolysaccharide-induced inflammatory responses in microglia

Background

Lidocaine has been used as a local anesthetic with anti-inflammatory properties, but its effects on neuroinflammation have not been well defined. In the present study, we investigated the prophylactic effects of lidocaine on lipopolysaccharide (LPS)-activated microglia and explored the underlying mechanisms.

Materials and methods

Microglial cells were incubated with or without 1 μg/mL LPS in the presence or absence of lidocaine, a p38 mitogen–activated protein kinase (p38 MAPK) inhibitor (SB203580), a nuclear factor-kappa B (NF-κB) inhibitor (pyrrolidine dithiocarbamate), or small interfering RNA. The protein and expression levels of inflammatory mediators, such as monocyte chemotactic protein 1, nitric oxide, prostaglandin E₂, interleukin 1β, and tumor necrosis factor α were measured using enzyme-linked immunosorbent assays and real-time polymerase chain reaction. The effect of lidocaine on NF-κB and p38 MAPK activation was evaluated using enzyme-linked immunosorbent assays, Western blot analysis, and electrophoretic mobility shift assay.

Results

Lidocaine (≥2 μg/mL) significantly inhibited the release and expression of nitric oxide, monocyte chemotactic protein 1, prostaglandin E₂, interleukin 1β, and tumor necrosis factor α in LPS-activated microglia. Treatment with lidocaine also significantly inhibited the phosphorylation of p38 MAPK and the nuclear translocation of NF-κB p50/p65, increased the protein levels of inhibitor kappa B-α. Furthermore, our study shows that the LPS-induced release of inflammatory mediators was suppressed by SB203580, pyrrolidine dithiocarbamate, and small interfering RNA.

Conclusions

Prophylactic treatment with lidocaine inhibits LPS-induced release of inflammatory mediators from microglia, and these effects may be mediated by blockade of p38 MAPK and NF-κB signaling pathways.     

Luminal Salmonella Endotoxin Affects Epithelial and Mast Cell Function in the Proximal Colon of Pigs

Background: The effects of proximal small-bowel resection on absorption and synthesis of cholesterol are unclear. Methods: To study cholesterol absorption and synthesis after proximal gut resections of variable length, plasma plant sterols, cholestanol, and cholesterol precursors were measured 1 and 2 months after 50% and 75% proximal small-bowel resection or transection. To examine the effect of increased crypt cell proliferation and brush border development on cholesterol absorption, the results were related to the mucosal morphology, crypt cell proliferation, and disaccharidase activities of the remaining small bowel. Results: Campesterol levels in proportion to cholesterol decreased markedly more, and those of cholestanol markedly less, than would be expected simply due to the amount of proximal small intestine removed, whereas sitosterol proportions decreased in proportion to the length of gut resection. Campesterol proportions markedly (P = 0.06) increased between 1 and 2 months after 50% resection but remained unchanged after 75% resection. Crypt cell proliferation was only increased in the 75% resection group (P < 0.05). The longer the proximal gut resection, the lower was the mucosal enzyme activity. Both resection groups showed increased plasma cholesterol precursor proportions and crypt depth (P < 0.05), whereas villus height remained unchanged. After massive proximal resection campesterol and sitosterol proportions were inversely related to crypt cell proliferation (r = -0.86-0.83, P < 0.01). Conclusions: Increased crypt cell proliferation activated by massive proximal gut resection may act as a previously unrecognized factor in aggravating cholesterol malabsorption and retarding its recovery during the early postoperative period. These findings warrant further investigation.     

高温复合脂多糖应激大鼠血清天门冬酸氨基转移酶的变化

目的:探讨高温与脂多糖(LPS)复合应激大鼠血清天门冬酸氨基转移酶(AST)含量的变化特点.方法:雄性SPF级Wistar大鼠64只随机均匀分为常温 生理盐水组(C组),高温 生理盐水组(H组),常温 LPS组(L组),高温 LPS组(HL组).置动物于模拟气候舱,HL和H组暴露环境干球温度(Tdb)为(35.0±0.5)℃,L和C组Tdb为(26±0.5)℃;HL和L组动物经尾静脉注射LPS 10 mg/kg,H和C组动物经尾静脉注射9 g/L NaCl 10 mL/kg.持续监测动物平均动脉压(MAP)的动态变化,检测动物应激0,40,80,120 min时血清AST等物质含量的变化.结果:AST在不同温度、时间、药物水平间存在统计学差异(P＜0.01);时间与温度、时间与药物、温度与药物交互作用有统计学意义(P＜0.05),120 min时相点HL组动物血清AST含量高于其余3组,差异有统计学意义(P＜0.01);AST水平与MAP存在负相关关系(r=-0.818,P=0.029).结论:高温与LPS复合应激可促发、扩大全身炎症反应综合征.     

肿瘤坏死因子和脂多糖影响牙周膜细胞表达骨保护因子的研究

目的　研究脂多糖 (lipopolysaccharide,LPS)和肿瘤坏死因子α(tumornecrosisfactor α,TNF α)对牙周膜细胞增殖及分泌骨保护因子 (osteoprotegerin ,OPG)的影响。 方法　培养牙周膜细胞并形成单细胞克隆 ,培养基中加入LPS和TNF α ,MTT法检测牙周膜细胞增殖水平 ,SandwitchELISA法测定培养上清液中OPG含量。结果　TNF α浓度在 1 0 μg/L以上时可增加细胞对OPG的表达量 (P <0 0 5) ,但由于TNF α同时抑制牙周膜细胞增殖 (P <0 0 5 ) ,因此培养上清中OPG总量无明显变化 (P >0 0 5) ;LPS对牙周膜细胞增殖和OPG表达均无明显影响 ,与TNF α也没有交互作用 (P >0 0 5)。结论　TNF α能刺激牙周膜细胞OPG表达水平的提高 ;牙周膜细胞可能不是牙周炎时LPS直接细胞毒作用的效应细胞     

细菌脂多糖对急性胰腺炎大鼠核因子-κB及肿瘤坏死因子的影响

目的探讨细菌脂多糖(LPS)对大鼠实验性急性胰腺炎(AP)核因子-κB(NF-κB)、肿瘤坏死因子(TNF-α)mRNA及病理改变的影响,了解LPS在AP发生中的作用.方法 24只Wistar大鼠分为3组:AP组、LPS干预组及对照组;AP组蛙皮素诱导产生AP;LPS干预组在AP组基础上,给予腹腔内注射大剂量LPS(2mg/kg);对胰腺组织标本进行病理评分;RT-PCR检测胰腺组织中TNF-α mRNA表达的变化;应用流式细胞术(FCM)检测NF-κB表达的改变.结果与AP组相比,病理结果显示,LPS干预组胰腺组织水肿程度及炎性细胞浸润和坏死明显加重,胰腺组织损伤程度明显加重(病理评分7.21±0.53us,3.65±0.37,P＜0.01);FCM显示由于LPS的作用,NF-κB的表达明显上调(61.28±7.56us,41.13±11.72,P＜0.05),胰腺组织内炎性介质TNF-αmRNA的表达也同步上调(3.798±0.438us,2.856±0.365,P＜0.05).结论 LPS有加重AP病情的作用,其可能机制是LPS通过激活NF-κB及TNF-α从而实现了上述病理损害.     

内毒素致新生大鼠肺组织PECAM-1,t-PA,PAI-1表达的改变及其意义

目的　制备新生大鼠肺损伤模型 ,探讨PECAM 1(血小板内皮细胞粘附因子 )和t PA(组织型纤溶酶原激活因子 ) ,PAI 1(纤溶酶原激活物抑制因子 )mRNA在新生大鼠肺损伤中的作用。方法　腹腔注射LPS致新生大鼠肺损伤 ,观察不同时间点肺组织大体 ,光镜和电镜的病理改变 ,应用免疫组化和RT PCR的方法分别检测肺组织PECAM 1蛋白及mRNA和t PA ,PAI 1mRNA的表达改变。结果　病理改变证实了新生大鼠肺出血的发生 ,注射LPS后 ,PECAM 1蛋白及mRNA表达逐渐下降 ,8h和 16h分别达最低值 (分别为 95 1± 9 76 ,0 86 1± 0 0 16 ) ,与正常对照组 (分别为 12 9 5± 6 15 ,1 192± 0 0 35 )相比 ,差异有显著意义 (P <0 0 1)。LPS作用后 ,t PA ,PAI 1mRNA在肺组织的表达呈逐渐上升趋势 ,t PAmRNA表达高峰为给药后 2h(1 195± 0 0 36 ) ,与对照组 (0 781± 0 0 17)比较 ,差异显著意义 (P <0 0 1)。PAI 1mRNA表达高峰为给药后 2～ 8h(分别为 1 178± 0 0 6 9,1 15 3± 0 0 36 ,1 176±0 0 4 4 ) ,与对照组 (0 6 81± 0 0 19)比较 ,差异显著意义 (P <0 0 1)。结论LPS作用于新生大鼠后 ,肺组织PECAM I蛋白及mRNA表达显著降低 ,保护性机制破坏 ;t PA和PAI 1mRNA表达增加 ,随着大鼠病情加重 ,平衡状态遭到破坏 ,局部     

氯化镧拮抗内毒素效应的小鼠体内研究

目的　探讨氯化镧对内毒素 (LPS)体内效应的拮抗作用 ,寻找新的有效内毒素拮抗剂 ,为防治内毒素血症提供实验依据。方法　 (1)观察不同方式给予氯化镧处理对半数致死量LPS(17 5mg/kg)攻击小鼠的死亡率的影响。 (2 )观察氯化镧对LPS(12 5mg/kg)攻击后小鼠血浆肿瘤坏死因α(TNFα)及肝脏TNFαmRNA表达水平的变化、胸腺细胞凋亡状况、肝肺的病理损伤状况的影响。结果　 (1)经 5、10、2 0mg/kg氯化镧处理的半数致死量LPS攻击小鼠的死亡率分别为 0、0和 8% ,明显低于对照组的死亡率 (6 7% ) (P <0 0 1)。 10mg/kg氯化镧预防性给药 ,半数致死量LPS攻击小鼠后死亡率为 2 0 % ,明显低于对照组死亡率 (5 5 % ) (P <0 0 5 )。 (2 )经氯化镧处理的内毒素血症小鼠血浆TNFα含量为 0 4 4± 0 2 15ng/ml,肝组织TNF αmRNA表达量为 (3 9± 0 6 )× 10 5拷贝 / μgRNA ,明显低于内毒素血症小鼠 [0 99± 0 2 4ng/ml,(1 9± 0 3)× 10 7拷贝 / μgRNA],P <0 0 0 1;经氯化镧处理的内毒素血症小鼠胸腺细胞DNA片段百分率为 30 35 %± 6 4 2 % ,明显低于未处理小鼠(5 5 38%± 3 88% ) (P <0 0 0 1) ;内毒素血症小鼠胸腺细胞凋亡百分率为 15 5 6 %± 0 5 9% ,明显高于氯化镧处理小鼠 (6 0 5 %± 0 71% ) (P <     

蛋白激酶对内毒素休克后内皮细胞骨架的作用

目的　探讨内毒素休克发病机制中蛋白激酶G(PKG)的作用。　方法　用脂多糖 (LPS)刺激培养的内皮细胞 ,通过细胞裂解和离心获得细胞裂解液 ,用放射性同位素法标记法检测PKG的活性。同时采用特异性荧光染色法检测LPS刺激后细胞内肌动蛋白微丝 (F actin)的结构和分布变化。用PKG特异性抑制剂KT5 82 3预处理细胞后 ,再检测LPS介导的细胞内PKG活性和F actin的变化。以空白组为阴性对照 ,以PKG激动剂 8 Br cGMP刺激细胞作为阳性对照组。　结果　LPS分别刺激 5、10、30和 6 0min后细胞内PKG活力呈时间依赖性的增高 (与空白组相比P <0 .0 1) ,细胞内的F actin出现极性分布 ;而KT5 82 3预刺激 2 0min后再用LPS刺激没有出现上述变化。PKG的激动剂 8 Br cGMP刺激细胞后的变化与LPS的刺激相似。　结论　LPS可以介导血管内皮细胞PKG的激活和F actin的应力性变化 ;内毒素休克后内皮细胞通透性增高与cGMP PKG通路的激活有关。