扑热息痛肝毒性中炎症反应的研究进展

扑热息痛（N-acetyl-para-aminophenol,APAP）是临床应用最广泛的解热镇痛药;作为肝毒性工具药物,APAP也被广泛用于药物肝毒性机制研究和测试药物的护肝潜力。炎症是加重细胞损伤的一个潜在因素,也能限制细胞损伤,清除细胞碎片和促进再生。30余年来,APAP肝毒性机制的研究和讨论一直在持续。笔者针对APAP肝毒性中的细胞内事件,尤其是与炎症反应、炎症介质、炎症细胞之间的关系进行综述,为临床应用和毒性机制研究提供参考。     

扑热息痛致小鼠肝细胞线粒体损伤机制的研究

目的 研究扑热息痛(APAP)引起小鼠肝细胞线粒体损伤的机制.方法 小鼠分为对照组及40、80、160、320 mg·kg-1APAP组,腹腔注射12 h后测定小鼠血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)的活力和肝组织中谷胱甘肽(GSH)的水平,测定肝细胞线粒体膜电位、肿胀敏感性及游离钙的含量.结果 与对照组相比,APAP组小鼠的血清中ALT、AST的活性显著增高、肝组织中GSH的水平降低,肝细胞线粒体的膜电位下降、肿胀敏感性下降,同时检测到80、160、320 mg·kg-1APAP组小鼠肝细胞线粒体内钙离子超载.随剂量的增大,APAP对小鼠各指标的影响逐渐增加.结论 随着APAP剂量增加,小鼠肝损伤加剧,线粒体损伤加重,可能与线粒体内钙超载导致线粒体的膜通透性转运孔高通透性开放有关.     

药源性肾损伤机制研究进展

肾脏是药物代谢和排泄的重要器官,其丰富的血流量与高的代谢活性也是肾脏易受药物不良反应而产生肾毒性的重要原因。近年来,由于各种药物尤其是抗生素的广泛应用及非合理性药物滥用,致使药物引起肾损害的报告日益增多。药物引起的肾脏疾病临床表现主要是急性肾损伤、梗阻性肾病、间质性肾炎、肾病综合征及酸碱失衡和水电解质紊乱。而不同药物导致不同的肾脏病症,诱导肾毒性的病理生理机制是复杂多样的。本文主要从细胞毒性中的氧化应激、溶酶体损伤、线粒体功能障碍和有机阴离子转运4个方面对引起药源性肾损伤分子机制作一综述,为临床用药中减少肾脏损伤提供帮助。     

经由线粒体损伤诱发的药源性肝损伤研究进展

线粒体是物质氧化和能量转换的场所,在能量代谢及自由基的产生、衰老、凋亡中起着重要作用。线粒体的呼吸链缺陷、代谢酶失活、结构改变、基因突变等因素都会影响整个细胞的正常功能,从而导致病变的发生。线粒体是药物毒性作用的重要靶标,肝脏作为药物代谢的重要脏器,也是药物引发损伤的主要靶器官。一些抗病毒药物、抗肿瘤药物和抗生素等可显著诱导肝脏线粒体损伤。药物主要通过改变线粒体结构、酶的活性或减少mtDNA的合成,进一步破坏β-脂质氧化和肝细胞的氧化能力,最终诱发肝损伤。综述药源性肝损伤领域有关线粒体损伤的研究进展,为预防和诊断药源性肝损提供思路。     

异烟肼致线粒体损伤引起药物性肝损伤研究进展

近年国内外研究表明,线粒体功能异常是各种肝损伤(肝功能衰竭、肝硬化、脂肪肝等)发生的重要机制之一,而在药物性肝损伤发展过程中线粒体也起着重要作用。异烟肼是临床应用广泛、效果显著的抗结核药,但在治疗过程中常引起药物性肝损伤。在某种程度上妨碍了结核病的治疗。研究发现线粒体损伤是异烟肼肝损伤发生发展中关键一环,异烟肼及其毒性产物肼可通过激动氧化应激反应;抑制线粒体呼吸链中酶的活性;干扰细胞能量代谢及对线粒体膜产生攻击等方式使其功能异常,最终导致线粒体损伤,进而启动细胞凋亡程序。本文将对线粒体在异烟肼致药物性肝损伤中的作用进行综述,旨在从亚细胞水平解释异烟肼致肝毒性的机制,为阐明异烟肼的肝毒性提供更为有力的证据。     

过氧化物酶体增殖物激活受体α在对乙酰氨基酚肝损伤的研究进展

对乙酰氨基酚(Acetaminophen,APAP)药物过量是我国及欧美国家急性肝衰竭的常见原因之一。正常剂量的APAP约90%以上经过肝内Ⅱ相代谢酶UDP-葡萄糖醛酸转移酶(UGT)和磺基转移酶(SULT)转化为无毒的葡萄糖醛酸盐或硫酸盐从肾脏和胆汁排泄,10%以下通过肝内I相代谢酶细胞色素P450酶转化为活性代谢产物N-乙酰基-对-苯醌亚胺(NAPQI),NAPQI随后在谷胱甘肽-S-转移酶(GST)的作用下转化为无毒的化合物。当APAP过量时,NAPQI蓄积,继而引起肝损伤。代谢性核受体过氧化物酶体增殖物激活受体α (Peroxisome proliferator activated receptor ,PPARα),作为核受体超家族成员之一,参与肝脏脂质代谢及多种生物转化过程,多个研究表明PPARα激动剂可保护APAP引起的肝损伤,该文将对PPARα在APAP引起的肝损伤中的作用及机制进行综述,以期为APAP诱导的肝损伤提供潜在的治疗靶点。     

浅谈扑热息痛的作用机制与合理使用

对扑热息痛是乙酰苯胺类解热镇痛药。1955年美国已经将此药列为非处方药，我国于1960年开始生产，在医药改革中实行药品分类管理第一批非处方药就有了对扑热息痛，作为非处方药，虽然有质量稳定，疗效确切的优点，但该药的滥用，使用不当也会产生不良反应或严重的肝毒性和肾毒性。因此已引起人们关注，有必要加深对该药的认识。     

纳米二氧化钛神经毒性及其机制的研究进展

纳米二氧化钛（TiO2 NPs）作为一种新型纳米材料,已成为多个领域的研究热点。随着在日常生活中接触TiO2 NPs愈发容易,TiO2 NPs的毒性也逐渐受到关注。TiO2 NPs能够通过血脑屏障进入脑内并蓄积,引起脑组织、神经细胞的损伤,影响情感与认知,降低学习记忆能力。本文主要对近年来TiO2 NPs引起的体内、外神经毒性,以及其毒性机制如氧化应激、炎症反应、凋亡等的研究现状进行综述,旨在丰富TiO2 NPs的毒性研究数据库,为其日常安全使用提供科学依据。     

美国FDA：药品限制扑热息痛成分含量，增加肝毒性警告

FDA现正要求牛产含扑热息痛成分药品的制造商,生产的药物中应限制扑热息痛的含量不超过325mg每片／胶囊。     

Intracellular signaling mechanisms of acetaminophen-induced liver cell death.

Acetaminophen hepatotoxicity is the leading cause of drug-induced liver failure. Despite substantial efforts in the past, the mechanisms of acetaminophen-induced liver cell injury are still incompletely understood. Recent advances suggest that reactive metabolite formation, glutathione depletion, and alkylation of proteins, especially mitochondrial proteins, are critical initiating events for the toxicity. Bcl-2 family members Bax and Bid then form pores in the outer mitochondrial membrane and release intermembrane proteins, e.g., apoptosis-inducing factor (AIF) and endonuclease G, which then translocate to the nucleus and initiate chromatin condensation and DNA fragmentation, respectively. Mitochondrial dysfunction, due to covalent binding, leads to formation of reactive oxygen and peroxynitrite, which trigger the membrane permeability transition and the collapse of the mitochondrial membrane potential. In addition to the diminishing capacity to synthesize ATP, endonuclease G and AIF are further released. Endonuclease G, together with an activated nuclear Ca2+,Mg2+-dependent endonuclease, cause DNA degradation, thereby preventing cell recovery and regeneration. Disruption of the Ca2+ homeostasis also leads to activation of intracellular proteases, e.g., calpains, which can proteolytically cleave structural proteins. Thus, multiple events including massive mitochondrial dysfunction and ATP depletion, extensive DNA fragmentation, and modification of intracellular proteins contribute to the development of oncotic necrotic cell death in the liver after acetaminophen overdose. Based on the recognition of the temporal sequence and interdependency of these mechanisms, it appears most promising to therapeutically target either the initiating event (metabolic activation) or the central propagating event (mitochondrial dysfunction and peroxynitrite formation) to prevent acetaminophen-induced liver cell death.     

Nuclear translocation of endonuclease G and apoptosis-inducing factor during acetaminophen-induced liver cell injury.

Mitochondrial dysfunction and internucleosomal DNA fragmentation are well-recognized features of acetaminophen (AAP)-induced hepatocyte cell death. However, the endonucleases responsible for this effect have not been identified. Apoptosis-inducing factor (AIF) and endonuclease G are nucleases located in the intermembrane space of mitochondria. AIF is thought to trigger chromatin condensation and induce cleavage of DNA into high molecular weight fragments (50-300 kb), and endonuclease G can produce oligonucleosomal DNA fragments. Therefore, the objective of this investigation was to test the hypothesis that endonuclease G and AIF could be involved in AAP-induced nuclear DNA fragmentation. Using immunofluorescence microscopy, it was shown that in primary cultured mouse hepatocytes, endonuclease G and AIF translocated to the nucleus between 3 and 6 h after exposure to 5 mM AAP. In contrast, other mitochondrial intermembrane proteins such as cytochrome c or the second mitochondria-derived activator of caspases (Smac) did not accumulate in the nucleus. The translocation of AIF and endonuclease G correlated with mitochondrial dysfunction as indicated by the progressive loss of the mitochondrial membrane potential (measured with the JC-1 assay) and the appearance of nuclear DNA fragments in the cytosol (determined by an anti-histone ELISA). Pretreatment with 20mM N-acetylcysteine prevented mitochondrial dysfunction, the nuclear translocation of endonuclease G and AIF, and the nuclear DNA fragmentation. The data support the conclusion that endonuclease G and AIF translocate to the nucleus in response to AAP-induced mitochondrial dysfunction and may be responsible, at least in part, for the initial DNA fragmentation during AAP hepatotoxicity.     

Gene expression profiling of rat livers reveals indicators of potential adverse effects.

This study tested the hypothesis that gene expression profiling can reveal indicators of subtle injury to the liver induced by a low dose of a substance that does not cause overt toxicity as defined by conventional criteria of toxicology (e.g., abnormal clinical chemistry and histopathology). For the purpose of this study we defined this low dose as subtoxic, i.e., a dose that elicits effects which are below the detection of conventional toxicological parameters. Acetaminophen (APAP) was selected as a model hepatotoxicant because (1) considerable information exists concerning the mechanism of APAP hepatotoxicity that can occur following high doses, (2) intoxication with APAP is the leading cause of emergency room visits involving acute liver failure within the United States, and (3) conventional clinical markers have poor predictive value. Rats treated with a single dose of 0, 50, 150, or 1500 mg/kg APAP were examined at 6, 24, or 48 h after exposure for conventional toxicological parameters and for gene expression alterations. Patterns of gene expression were found which indicated cellular energy loss as a consequence of APAP toxicity. Elements of these patterns were apparent even after exposure to subtoxic doses. With increasing dose, the magnitude of changes increased and additional members of the same biological pathways were differentially expressed. The energy loss suggested by gene expression changes was confirmed at the 1500 mg/kg dose exposure by measuring ATP levels. Only by ultrastructural examination could any indication of toxicity be identified after exposure to a subtoxic dose of APAP and that was occasional mitochondrial damage. In conclusion, this study provides evidence that supports the hypothesis that gene expression profiling may be a sensitive means of identifying indicators of potential adverse effects in the absence of the occurrence of overt toxicity.     

Connexin32: a mediator of acetaminophen-induced liver injury?

Connexin32 is the building block of hepatocellular gap junctions, which control direct intercellular communication and thereby act as goalkeepers of liver homeostasis. This study was set up to investigate whether connexin32 is involved in hepatotoxicity induced by the analgesic and antipyretic drug acetaminophen. To this end, whole body connexin32 knock-out mice were overdosed with acetaminophen followed by sampling at different time points within a 24-h time frame. Evaluation was done based upon a series of clinically and mechanistically relevant read-outs, including protein adduct formation, histopathological examination, measurement of alanine aminotransferase activity, cytokine production, levels of reduced and oxidized glutathione and hepatic protein amounts of proliferating cell nuclear antigen. In essence, it was found that genetic ablation of connexin32 has no influence on several key events in acetaminophen-induced hepatotoxicity, including cell death, inflammation or oxidative stress, yet it does affect production of protein adducts as well as proliferating cell nuclear antigen steady-state protein levels. This outcome is not in line with previous studies, which are contradicting on their own, as both amplification and alleviation of this toxicological process by connexin32 have been described. This could question the suitability of the currently available models and tools to investigate the role of connexin32 in acetaminophen-triggered hepatotoxicity.     

Acetaminophen-induced oxidant stress and cell injury in cultured mouse hepatocytes: protection by N-acetyl cysteine.

The increase in cellular and mitochondrial glutathione disulfide (GSSG) levels and the GSSG:GSH ratio after acetaminophen (AAP) overdose suggest the involvement of an oxidant stress in the pathophysiology. However, the initial severe depletion of hepatocellular glutathione makes quantitative assessment of the oxidant stress difficult. Therefore, we tested the hypothesis that oxidant stress precedes the onset of cell injury in a cell culture model using 2',7'-dichlorofluorescein (DCF) fluorescence as a marker for intracellular oxidant stress. Cultured primary murine hepatocytes were exposed to 5 mM AAP. DCF fluorescence, XTT reduction, lactate dehydrogenase (LDH) release, and trypan blue uptake were determined from 0 to 12 h. After glutathione depletion at 3 h, DCF fluorescence increased by 16-fold and was maintained at that level up to 12 h. At 1.5 h after AAP, a significant decrease of the cellular XTT reduction capacity was observed, which continued to decline until 9 h. Cell necrosis (LDH release, trypan blue uptake) was detectable in 20% of cells at 6 h, with a significant further increase at later time points. Pretreatment with 20 mM N-acetylcysteine (NAC) 1 h before AAP enhanced cellular glutathione content, prevented or attenuated the AAP-induced decrease of GSH levels and XTT reduction capacity, respectively, and reduced the loss of cell viability. Additionally, treatment with NAC 2 h after AAP exposure prevented further deterioration of XTT reduction at 3 h and later, and attenuated cell necrosis. Thus, AAP-induced oxidant stress precedes cell necrosis and, in cultured hepatocytes, the oxidant stress is involved in the propagation of cell injury.     

Thearubigins protect against acetaminophen-induced hepatic and renal injury in mice: biochemical,histopathological, immunohistochemical,and flow cytometry study

Context: Acetaminophen toxicity is used as a model for studying chemical toxicity. N-acetylcysteine (NAC) is used for the treatment of hepatotoxicity; however, there is no specific therapy for nephrotoxicity. Objective: This study was designed to investigate the potential protective effect of black tea extract (BTE) and its main phenolic pigment, thearubigins (TRs), against acetaminophen (APAP)-induced hepatic and renal injury in mice. Materials and methods: Besides control groups, six groups (n?=?8) were given intraperitoneally APAP (300?mg/kg) and then after 1.5 hours were treated intraperitoneally as follows: NAC (318?mg/kg), BTE (3%, 4.5%), and TRs (50, 60, and 70?mg/kg). Six hours post-APAP injection, blood was collected for biochemical measurements. Later, liver and kidneys were removed for histopathological, immunohistochemical, and flow cytometry studies. Results: APAP increased alanine aminotransferase and malondialdehyde and decreased glutathione levels in blood. Treatments significantly reversed these changes mostly with NAC and TRs70. TRs showed dose-dependent significant differences. The APAP-induced central lobular hepatic necrosis and increased TUNEL positivity were mild with co-administration of NAC and TRs (60,?70) while moderate with co-administration of BTE (3,?4.5) and TRs50. The APAP-increased serum creatinine level was significantly reversed by treatments (mostly TRs60,?70). The APAP-induced renal tubular epithelial degeneration and necrosis were mild with co-administration of TRs (60,?70) while moderate with co-administration of NAC, BTE (3,?4.5), and TRs50. The APAP-accumulated apoptotic cells in sub-G₁ phase were significantly decreased by treatments, mostly by NAC and TRs70 in the liver and TRs (60,?70) in kidneys. Conclusion: Thearubigins protected against acetaminophen-induced hepatotoxicity and nephrotoxicity in mice possibly through their antioxidant activity.     

Protective effect of Woodfordia fruticosa flowers against acetaminophen-induced hepatic toxicity in rats

Context: The flowers of Woodfordia fruticosa Kurz. (Lythraceae) are commonly used for the treatment of several ailments which includes rheumatism, leucorrhea, menorrhagia, asthma, liver disorder, and inflammatory conditions.

Objective: To evaluate the hepatoprotective property of Woodfordia fruticosa flowers against acetaminophen-induced hepatic injury in rats.

Material and methods: Acetaminophen (3?g/kg bw)-induced hepatotoxicity study was carried out by observing the effect of methanol extract of Woodfordia fruticosa flowers (400 and 600?mg/kg, bw) on some serum marker enzymes, albumin, blood urea nitrogen levels as well as liver total protein, nonenzymetic glutathione reduced content, and enzymatic antioxidant glutathione peroxidase, with histopathological evidence.

Results and discussion: Pretreatment of rats with methanol extract of Woodfordia fruticosa flowers effectively prevented the acetaminophen-induced hepatic damage as indicated by the serum marker enzymes aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase and other biochemical parameters (albumin and blood urea nitrogen). Parallel to these changes, the methanol extract of Woodfordia fruticosa flowers also prevented acetaminophen-induced oxidative stress in the rat liver by inhibiting depletion of liver total protein and restoring the levels of nonenzymatic antioxidant glutathione reduced. The biochemical changes were consistent with histopathological observations suggesting marked hepatoprotective effect of the methanol extract of Woodfordia fruticosa flowers.

Conclusion: The results suggested that methanol extract of Woodfordia fruticosa flowers possesses protective effect against acetaminophen-induced hepatotoxicity.     

基于代谢组学研究二苯乙烯苷在对乙酰氨基酚诱导小鼠肝损伤中的保护作用

目的:通过非靶向代谢组学等研究方法探讨二苯乙烯苷(tetrahydroxy stilbene glucoside,TSG)对乙酰氨基酚(acetaminophen,APAP)造成急性肝损伤的保护作用。方法:采用随机分组方式将SPF级C57BL/6小鼠分为APAP模型组和TSG干预组,每组15只。灌胃给予小鼠TSG连续7 d后,一次性腹腔注射APAP进行造模,6 h后取肝脏组织。结果:H&E染色、MDA和SOD检测表明单次APAP注射会造成肝脏损伤,TSG干预会降低肝脏受损程度。代谢产物检测结果显示,与APAP模型组相比,TSG组的ABC转运体、胆碱代谢、中心碳代谢、半乳糖、丙氨酸类氨基酸代谢等变化显著。结论:TSG通过改善脂质过氧化和能量代谢紊乱等过程抵御APAP导致的急性肝损伤。     

Effect of H2-receptor antagonists on acetaminophen-induced hepatic injury

The effects of H2-antagonists on acetaminophen-induced hepatic injury were examined. Rats were administered acetaminophen at the dose of 800 mg/kg body, 60 hr after injection of 3-methylcholanthrene. As an H2-antagonist, cimetidine (200 mg/kg), ranitidine (50 mg or 100 mg/kg), or famotidine (20 mg or 40 mg/kg) was administered before and after acetaminophen injection. The group administered only acetaminophen had been severely damaged as evaluated by changes in serum transaminase, P-450 content, aminopyrine demethylation, glutathione content and histological study, but administration of 200 mg cimetidine together with acetaminophen significantly reduced the hepatic injury to nearly the control level. Ranitidine had no protective effect against hepatic injury at the dose of 50 mg, which appears to have the same antacid effect as 200 mg cimetidine, whereas it had a slight but significant protective effect as evaluated by the transaminase level, glutathione content and histological study at the dose of 100 mg. Famotidine had no effect against acetaminophen induced hepatic injury. Because famotidine had no effect, the protection by H2-antagonist against acetaminophen-induced hepatic injury cannot be explained by the decrease in hepatic blood flow alone. Therefore, inhibition of P-450 activity seems to be more important for reducing the generation of the reactive metabolites of acetaminophen than hepatic blood flow decrease.     

Differential susceptibility to acetaminophen-induced liver injury in sub-strains of C57BL/6 mice: 6N versus 6J

Mouse models of acetaminophen (APAP) hepatotoxicity are considered relevant for the human pathophysiology. The C57BL/6 strain is most popular because it is the background strain of gene knock-out mice. However, conflicting results in the literature may have been caused by sub-strain mismatches, e.g. C57BL/6J and C57BL/6N. This study was initiated to determine the mechanism behind the sub-strain susceptibility to APAP toxicity. C57BL/6N and C57BL/6J mice were dosed with 200 mg/kg APAP and sacrificed at different time points. C57BL/6N mice developed significantly more liver injury as measured by plasma ALT activities and histology. Although there was no difference in glutathione depletion or cytochrome P450 activity between groups, C57BL/6N had a higher glutathione disulfide-to-glutathione ratio and more APAP protein adducts. C57BL/6N showed more mitochondrial translocation of phospho-JNK and BAX, and more release of mitochondrial intermembrane proteins apoptosis-inducing factor (AIF), second mitochondria-derived activator of caspases (SMAC), which caused more DNA fragmentation. The increased mitochondrial dysfunction was confirmed in vitro as C57BL/6N hepatocytes had a more precipitous drop in JC-1 fluorescence after APAP exposure. Conclusion: C57BL/6N mice are more susceptible to APAP-induced hepatotoxicity, likely due to increased formation of APAP-protein adducts and a subsequent enhancement of mitochondrial dysfunction associated with aggravated nuclear DNA fragmentation.