弓形虫感染对大鼠记忆力影响及其机制的实验研究

目的观察弓形虫感染对大鼠学习记忆能力和海马组织细胞因子(白细胞介素-1β、肿瘤坏死因子-α、白细胞介素-6)水平以及大脑皮层一氧化氮合酶(NOS)活性的影响,探讨其可能机制。方法40只清洁级SD大鼠随机分成4组,即对照组和高、中、低感染剂量的弓形虫感染组(2×107/ml×2ml、2×105/ml×2ml、2×103/ml×2ml)。9周后进行被动回避实验和Morris水迷宫试验,观察弓形虫感染对大鼠的学习记忆能力等行为学变化。放射免疫法检测大鼠海马组织IL-1β、IL-6、TNF-α水平,免疫组化检测NOS活性。结果弓形虫感染对大鼠的记忆获得没有影响,但高、中剂量弓形虫感染组大鼠的记忆消失要早于对照组(P<0.05),低感染剂量组大鼠记忆消失与正常对照大鼠比较,差异无统计学意义(P>0.05)。各感染组大鼠Morris水迷宫测试中逃避潜伏期均明显延长,其距离百分比明显降低(P<0.05)。各感染组大鼠海马组织IL-1β、TNF-α水平明显高于对照组(P<0.05);但IL-6水平与对照组相比差异无显著性(P>0.05)。感染组大鼠大脑皮层NOS阳性细胞数增加。结论弓形虫感染对大鼠的学习记忆能力有影响,其作用机制之一可能与大鼠海马组织IL-1β、TNF-α细胞因子水平升高有关。

Ethyl pyruvate protects against experimental acute-on-chronic liver failure in rats

AIM： To investigate the protective effects of ethyl py- ruvate （EP） on acute-on-chronic liver failure （ACLF） in rats. METHODS： An ACLF model was established in rats, and animals were randomly divided into normal, mod- el and EP treatment groups. The rats in EP treatment group received EP （40 mg/kg） at 3 h, 6 h, 12 h and 24 h after induction of ACLF. Serum endotoxin, high mobility group box-1 （HMGB1）, alanine transaminase （ALT）, tumor necrosis factor-α （TNF-α）, interferon-α （IFN-γ）, interleukin （IL）-10 and IL-18 levels, changes of liver histology and HMGB1 expressions in liver tis- sues were detected at 48 h after induction of ACLF. The effects of EP on the survival of ACLF rats were also observed.RESULTS： Serum levels of endotoxin （0.394 ± 0.066 EU/mL vs 0.086±0.017 EU/mL, P 〈 0.001）, HMGB1 （35.42±10,86 μg/L vs 2.14 ± 0.27 μg/L, P 〈 0.001）, ALT （8415.87 ± 3567.54 IU/L vs 38.64 ± 8.82 IU/L, P 〈 0.001）, TNF-α （190.77 ± 12.34 ng/L vs 124.40 ± 4.12 ng/L, P 〈 0.001）, IFN-γ （715.38 ± 86.03 ng/L vs 398.66 ± 32.91 ng/L, P 〈 0.001）, IL-10 （6.85 ± 0.64 ng/L vs 3.49 ± 0.24 ng/L, P 〈 0.001） and IL-18 （85.19 ±3.49 ng/L vs 55.38 ±1.25 ng/L, P 〈 0.001） were significantly increased, and liver tissues presented se- vere pathological injury in the model group compared with the normal group, Howeverr EP administration significantly improved hepatic histopathology and re- duced the serum levels of endotoxin （0.155±0.045 EU/mL vs 0.394 ± 0.066 EU/mL vs P 〈 0.001） and in- flammatory cytokines （11.13 ± 2.58 μg/L vs 35.42 ± 10.86 μg/L for HMGB1, 3512.86 ± 972.67 IU/L vs 8415.87 ± 3567.54 IU/L for ALT, 128.55 ± 5.76 ng/L vs 190.77 ± 12.34 ng/L for TNF-α 438.16 ± 38.10 ng/L vs 715.38 ± 86.03 ng/L for IFN-γ 3.55 ± 0.36 ng/L vs 6.85 ± 0.64 ng/L for IL-10, and 60.35 ± 1.63 ng/L vs 85.19 ± 3.49 ng/L for IL-18, respectively, P 〈 0.001）, and the levels of HMGB1 in liver tissues re- gardless of treatment time after induction of ACLF. EP treatment at the four time points prolonged the me- dian survival time of ACLF rats （60 h） to 162 h, 120 h, 102 h and 78 h, respectively （χ2 = 41.17, P 〈 0.0001）. CONCLUSION： EP administration can protect against ACLF in rats, and is a potential and novel therapeutic agent for severe liver injury.

Local Expression of Vaginal Th1 and Th2 Cytokines in Murine Vaginal Candidiasis under Different Immunity Conditions

To investigate the expression of vaginal Th1 and Th2 cytokines in rats with experimental vaginal candidiasis under different immune conditions, ICR murine vaginal candidiasis model was established and immno-suppressed murine models of vaginal cadidiasis were established in estrogen-treated mice. Non-estrogen-treated mice were used as controls. The mRNA level of Th1 （IL-2）/Th2 （IL-4, IL-10, TGF-β1） cytokines in murine vaginal tissues was determined by RT-PCR. The cykotine in local tissues was increased to different extent under normal immune condition. IL-2 mRNA was increased during early stage of infection, while IL-10 was increased transiently during late stage of infection. TGF-β1 production was found to be increased persistently. At same time, the expression of IL-2 mRNA was suppressed in immno-suppressed group, and the level of IL-4, IL-10, and TGF-β1 were higher than the normal immunity group to different degree during infection. The high level of IL-2 mRNA during early stage of infection was associated with clearance of mucosal Candidia albicans （C. albicans）, and its expression suppressed leading to decreased clearance of mucosal C. albican in immuno-suppression. The over-expression of IL-4 and IL-10 could significantly enhance the susceptibility to C. albicans infection in mice.

Mechanisms of hepatic ischemia-reperfusion injury and protective effects of nitric oxide

Hepatic ischemia-reperfusion injury(IRI) is a patho-physiological event post liver surgery or transplantation and significantly influences the prognosis of liver func-tion. The mechanisms of IRI remain unclear, and effec-tive methods are lacking for the prevention and therapy of IRI. Several factors/pathways have been implicated in the hepatic IRI process, including anaerobic metabo-lism, mitochondria, oxidative stress, intracellular cal-cium overload, liver Kupffer cells and neutrophils, and cytokines and chemokines. The role of nitric oxide(NO)in protecting against liver IRI has recently been report-ed. NO has been found to attenuate liver IRI through various mechanisms including reducing hepatocellular apoptosis, decreasing oxidative stress and leukocyte adhesion, increasing microcirculatory flow, and enhanc-ing mitochondrial function. The purpose of this review is to provide insights into the mechanisms of liver IRI, indicating the potential protective factors/pathways that may help to improve therapeutic regimens for control-ling hepatic IRI during liver surgery, and the potential therapeutic role of NO in liver IRI.