乙酰半胱氨酸对四氯化碳诱导的原代培养大鼠肝细胞损伤的保护作用

目的观察乙酰半胱氨酸（NAC）对四氯化碳（CCl4）诱导的原代培养大鼠肝细胞损伤的作用。方法在24孔细胞培养板上,用CCl4诱导原代培养肝细胞损伤,分别加入不同浓度的NAC,培养20 h后,测定上清液谷草转移酶（AST）活性,并MTT法检测细胞活力。结果 NAC在100μmol.L-1内,对正常培养的大鼠肝细胞没有影响;在4～100μmol.L-1内,NAC能剂量依赖性地抑制CCl4诱导的肝细胞活性的降低,EC50约为20μmol.L-1;当浓度为100μmol.L-1时,可以逆转CCl4诱导的肝损伤,使肝细胞释放AST降到接近正常水平,并明显改善肝细胞形态学变化。结论 NAC对CCl4诱导的肝损伤具有保护作用。     

肝细胞生长因子对四氯化碳损伤原代培养大鼠肝细胞的保护作用

采用大鼠离体肝细胞原代培养２４ｈ，并利用ＣＣｌ４造成急性肝细胞损伤模型，检定肝细胞生长因子（ＨＧＦ）对肝细胞损伤的影响．结果表明：ＨＧＦ可显著降低中毒肝细胞及细胞膜脂质过氧化物水平，抑制肝细胞脂质过氧化，并降低谷丙转氨酶和谷草转氨酶水平，稳定质膜；显著促进中毒肝细胞ＲＮＡ和ＤＮＡ的合成；超微病理证实ＨＧＦ能减轻ＣＣｌ４对肝细胞质膜，染色质，线粒体，内质网及核蛋白体的损害     

肝细胞生长因子对四氯化碳损伤原代培养大鼠肝细胞的保护作用

采用大鼠离体肝细胞原代培养24 h，并利用CCl₄造成急性肝细胞损伤模型，检定肝细胞生长因子(HGF)对肝细胞损伤的影响. 结果表明：HGF可显著降低中毒肝细胞及细胞膜脂质过氧化物水平, 抑制肝细胞脂质过氧化, 并降低谷丙转氨酶和谷草转氨酶水平, 稳定质膜；显著促进中毒肝细胞RNA和DNA的合成；超微病理证实HGF能减轻CCl₄对肝细胞质膜，染色质, 线粒体, 内质网及核蛋白体的损害.     

虎杖苷对CCl_4损伤原代培养大鼠肝细胞的保护作用

目的研究虎杖苷（ＰＤ）对ＣＣｌ４损伤原代培养大鼠肝细胞的保护作用。方法原位灌流法分离大鼠肝细胞，培养２４ｈ后加入ＰＤ，同时造成ＣＣｌ４损伤，分别于损伤后６，１２，２４和４８ｈ测培养液中谷丙转氨酶（ＡＬＴ）、丙二醛（ＭＤＡ）和还原型谷胱甘肽（ＧＳＨ）活性，４８ｈ后用ＭＴＴ比色法测肝细胞存活率。结果ＰＤ１×１０－７～１×１０－４ｍｏｌ·Ｌ－１能不同程度地抑制ＡＬＴ和ＭＤＡ的上升，提高ＧＳＨ水平，显著提高细胞存活率，以１×１０－５ｍｏｌ·Ｌ－１效果最好。结论ＰＤ１×１０－７～１×１０－４ｍｏｌ·Ｌ－１能有效保护ＣＣｌ４造成的原代培养大鼠肝细胞损伤     

五味子多糖对原代大鼠肝细胞氧化应激损伤的保护机制研究

目的探讨五味子多糖对原代大鼠肝细胞氧化应激的保护效应,并对其作用机制进行研究。方法体外培养原代大鼠肝细胞,分为空白对照组、H2O2诱导组、H2O2+低剂量五味子多糖组、H2O2+中剂量五味子多糖组、H2O2+高剂量五味子多糖组;CCK-8试剂检测大鼠肝细胞相对存活率,相关试剂盒检测NO、MDA含量,Western blot检测大鼠肝细胞中P67-phox、P47-phox、SOD1、HO-1、Rac1、p-Rac1蛋白表达水平。结果与H2O2诱导组相比,不同浓度五味子多糖可明显提升大鼠肝细胞的存活率(P<0.05);与H2O2诱导组相比,不同剂量五味子多糖可明显抑制细胞中NO、MDA的生成(P<0.05);Western blot检测显示,不同剂量五味子多糖可明显促进抗氧化蛋白HO-1、SOD1表达,抑制促氧化蛋白P67-phox、P47-phox的表达,并且五味子多糖显著抑制Rac1的磷酸化(P<0.05)。结论五味子多糖可明显改善大鼠肝细胞氧化应激损伤,其作用机制可能与抑制Rac1的磷酸化有关。     

玉郎伞多糖对四氯化碳诱导大鼠原代肝细胞损伤的保护作用

目的:研究玉郎伞多糖(YLS)对大鼠原代肝细胞损伤的保护作用及其机制。方法:采用IV型胶原酶灌流法分离大鼠肝细胞进行原代培养,用四氯化碳(CCl4)体外诱导肝细胞损伤,检测培养上清液中天门冬氨酸转换酶(AST)和丙氨酸氨基转换酶(ALT)水平,测定肝细胞中丙二醛(MDA)和谷胱甘肽(GSH)含量,MTT法检测细胞存活和增殖活性。结果:YLS(0.125~1.000g.L-1)可明显降低由CCl4升高的肝细胞培养上清液中AST和ALT水平及肝细胞MDA含量,还可提高CCl4降低的肝细胞存活率和GSH含量。结论:提示YLS对大鼠原代培养肝细胞损伤有直接保护作用,该作用可能与其抗氧化作用有关。     

龙眼参多糖对四氯化碳诱导大鼠原代肝细胞损伤的保护作用

目的:研究龙眼参多糖(LYS)对大鼠原代肝细胞损伤的保护作用及其机制。方法:用四氯化碳(CCl4)体外诱导大鼠原代肝细胞损伤,检测培养上清液中天门冬氨酸转移酶(AST)和丙氨酸氨基转移酶(ALT)水平,测定肝细胞中丙二醛(MDA)和谷胱甘肽(GSH)含量,四甲基偶氮唑盐(MTT)法检测细胞活性。结果:与模型组比较,LYS组AST和ALT水平及肝细胞MDA含量明显降低,肝细胞存活率和GSH含量升高。结论:LYS对大鼠原代培养肝细胞损伤有直接保护作用,机制可能与其抗氧化作用有关。     

海兔素对大鼠原代肝细胞酒精性氧化损伤的保护作用

目的探讨海兔素对大鼠原代肝细胞酒精性氧化损伤保护作用。方法门静脉胶原酶Ⅳ原位灌注及密度梯度离心获得大鼠原代肝细胞。MTT实验检测乙醇和海兔素最佳作用剂量及肝细胞活力。酶学实验检测细胞AST、LDH、SOD、MDA、GSH水平;流式细胞术检测细胞凋亡情况;单细胞凝胶电泳观察细胞DNA损伤状况;JC-1荧光探针检测细胞线粒体膜电位水平;比色法及Western blot检测细胞CYP2E1活性及蛋白表达。结果经30 mg·L~(-1)。海兔素预作用2 h,再与300 mmol·L~(-1)。乙醇共作用8 h后,肝细胞活力较酒精模型组明显上升,AST和LDH释放也得到明显抑制;同时,肝细胞SOD和GSH水平明显升高,MDA含量则明显降低,差异均具有显著性(P<0.05)。海兔素干预后,肝细胞凋亡率明显降低,DNA损伤及线粒体膜电位水平明显得到改善。海兔素干预后,肝细胞CYP2E1活性及蛋白表达水平明显受到抑制(P<0.05)。结论海兔素对大鼠原代肝细胞酒精性氧化损伤具有保护作用,其作用机制可能与海兔素抑制酒精对CYP2E1的活化,缓解氧化应激,提高机体抗氧化能力有关。     

胰岛素对大鼠肝细胞损伤的保护作用

目的:探讨胰岛素对大鼠肝细胞损伤是否具有保护作用。方法:胶原酶原位灌流分离大鼠肝细胞并原代培养,分别用脂多糖(LPS)及胰岛素处理肝细胞,12 h后检测肝细胞损伤及存活率。结果:LPS可引起肝细胞损伤,使丙氨酸氨基转移酶(ALT)和天门冬氨酸氨基转移酶(AST)增高;胰岛素可减轻上述肝细胞损伤(ALT活性降低55.5%、AST活性降低24.4%,P<0.01),提高肝细胞存活率(P<0.01)。结论:胰岛素可减少ALT和AST释放,促进肝细胞存活,减轻LPS直接诱导的肝细胞损伤,保护受损的肝细胞。     

南沙参多糖对四氯化碳损伤原代培养大鼠肝细胞保护作用的研究

目的:探讨南沙参多糖(RAPS)对四氯化碳(CCl4)损伤原代培养大鼠肝细胞的保护作用及其机制。方法:通过原位灌流法分离大鼠肝细胞,培养36h后加入RAPS,同时造成CCl4损伤,分别于损伤24h和48h时检测培养液中丙二醛(MDA)的含量、丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)的活性,48h后用MTT法测定肝细胞存活率。结果:RAPS对CCl4引起的ALT、AST活力的升高有抑制作用,同时抑制MDA的产生及肝细胞损伤造成的SOD活性及GSH-PX活性的降低。而且能明显改善肝细胞存活率。结论:RAPS能有效抑制CCl4造成的原代培养大鼠肝细胞损伤,机制可能与其抗氧化作用有关。     

Effects of model inducers on thyroxine UDP-glucuronosyl-transferase activity in vitro in rat and mouse hepatocyte cultures.

Thyroxine (T₄)-UDP-glucuronosyltransferase (UGT) activity was measured directly in cultured male Sprague–Dawley rat and OF-1 mouse hepatocyte monolayers. The activity of T₄-UGT (pmol/min/g liver) in vitro in hepatocyte cultures was, after 24 hr in culture, equivalent to that previously measured in vivo in rat and mouse liver microsomes (Viollon-Abadie et al., 1999). A progressive decline in T₄-UGT activity occurred over time in both rat and mouse hepatocyte cultures. Treatment of cultures with various model inducers such as phenobarbital (PB), β-naphthoflavone (NF) and clofibric acid (CLO) induced a strong increase in T₄-UGT activity in rat hepatocyte monolayers. In addition, and as expected from available in vivo data, treatment of rat hepatocyte cultures with NF also increased p-nitrophenol (PNP)-UGT activity and treatment with PB or CLO increased bilirubin (Bili)-UGT activity. In contrast, T₄-UGT activity in mouse hepatocyte monolayers was not affected by the treatments, neither were PNP- and Bili- UGT activities. These in vitro data confirm our previous in vivo observations that these inducers increase rat but not mouse liver T₄-UGT activities (Viollon-Abadie et al., 1999). The present study thus demonstrates that hepatocyte monolayers are appropriated for the evaluation and inter-species comparison of the effects of xenobiotics on T₄-UGT activities.     

Effects of model inducers on thyroxine UDP-glucuronosyl-transferase activity in vitro in rat and mouse hepatocyte cultures

Thyroxine (T₄)-UDP-glucuronosyltransferase (UGT) activity was measured directly in cultured male Sprague–Dawley rat and OF-1 mouse hepatocyte monolayers. The activity of T₄-UGT (pmol/min/g liver) in vitro in hepatocyte cultures was, after 24 hr in culture, equivalent to that previously measured in vivo in rat and mouse liver microsomes (Viollon-Abadie et al., 1999). A progressive decline in T₄-UGT activity occurred over time in both rat and mouse hepatocyte cultures. Treatment of cultures with various model inducers such as phenobarbital (PB), β-naphthoflavone (NF) and clofibric acid (CLO) induced a strong increase in T₄-UGT activity in rat hepatocyte monolayers. In addition, and as expected from available in vivo data, treatment of rat hepatocyte cultures with NF also increased p-nitrophenol (PNP)-UGT activity and treatment with PB or CLO increased bilirubin (Bili)-UGT activity. In contrast, T₄-UGT activity in mouse hepatocyte monolayers was not affected by the treatments, neither were PNP- and Bili- UGT activities. These in vitro data confirm our previous in vivo observations that these inducers increase rat but not mouse liver T₄-UGT activities (Viollon-Abadie et al., 1999). The present study thus demonstrates that hepatocyte monolayers are appropriated for the evaluation and inter-species comparison of the effects of xenobiotics on T₄-UGT activities.     

Inhibition of bone resorption in culture by (+)-catechin

A pretreatment with (+)-catechin renders embryonic mouse calvaria in culture resistant to the action of bone resorbing agents, either parathyroid hormone (PTH), prostaglandin E2 or retinoic acid, and inhibits in a parallel way the enhanced excretion of N-acetyl-beta-glucosaminidase, a reference lysosomal enzyme, induced by these agents; it has, however, no effect on the small spontaneous leakage of lactate dehydrogenase from the explants. Moreover, the resorption induced in calvaria by a pretreatment with PTH or retinoic acid is inhibited by a further culture with catechin. This inhibition of bone resorption is discussed in relation with the collagen-stabilizing properties of (+)-catechin.     

Acetaminophen toxicity in rat and mouse hepatocytes in vitro

Context: Acetaminophen (APAP) hepatotoxicity is often studied in primary cultures of hepatocytes of various species, but there are only few works comparing interspecies differences in susceptibility of hepatocytes to APAP in vitro. Objectives: The aim of our work was to compare hepatotoxicity of APAP in rat and mouse hepatocytes in primary cultures. Materials and methods: Hepatocytes isolated from male Wistar rats and C57Bl/6J mice were exposed to APAP for up to 24?h. We determined lactate dehydrogenase (LDH) activity in culture medium, activity of cellular dehydrogenases (WST-1) and activity of caspases 3 in cell lysate as markers of cell damage/death. We assessed content of intracellular reduced glutathione, production of reactive oxygen species (ROS) and malondialdehyde (MDA). Respiration of digitonin-permeabilized hepatocytes was measured by high resolution respirometry and mitochondrial membrane potential (MMP) was visualized (JC-1). Results: APAP from concentrations of 2.5 and 0.75?mmol/L induced a decrease in viability of rat (p?p?Conclusion: APAP displayed dose-dependent toxicity in hepatocytes of both species. Mouse hepatocytes in primary culture however had approximately three-fold higher susceptibility to the toxic effect of APAP when compared to rat hepatocytes.     

Structure-activity relationships for thiol reactivity and rat or human hepatocyte toxicity induced by substituted p-benzoquinone compounds

Covalent binding of toxic chemicals to cellular targets is a molecular interaction that initiates a wide array of adverse biological effects. The creation of a covalent bond can be cited as a key initiating step along many toxicity pathways which must be predicted in order to predict the potential of a chemical to cause specific harmful effects. Currently, quantitative structure-activity relationship (QSAR) models are being improved by focusing on endpoints such as simple electrophile reactivity for covalent interactions rather than on commonly used complex toxicity endpoints. The cytotoxicity and electrophilic reactivity of 10 p-substituted benzoquinone derivatives, which are well known electrophilic alkylating agents, were investigated under the premise that QSAR toxicity models can be improved when the molecular triggering event is considered. Hepatocyte toxicity was determined by incubation of individual compounds with freshly isolated rat or cryopreserved human hepatocyte suspensions. The potential for chemical reactivity between a chemical and cellular target was measured by determining non-enzymic reactivity with glutathione, representing thiol nucleophiles. The decline in free thiol moieties was measured to characterize the electrophile reactivity. It was found that the degree of rat hepatotoxicity induced by benzoquinones correlated with the rate at which they non-enzymically react with glutathione and to various global and atomic electronic frontier orbital parameters which described electrophilicity. Human hepatocytes showed similar results but the statistical significance was much lower. The QSAR expressions suggest that covalent binding reactivity serves as a good correlate to hepatotoxicity and could improve QSAR modeling for potential toxicity risks.     

Benoxaprofen induced toxicity in isolated rat hepatocytes

The toxicity of benoxaprofen, a non-steroidal anti-inflammatory compound was investigated using rat hepatic microsomal and isolated hepatocyte suspensions. In microsomes, benoxaprofen produced a Type I binding spectra and competitively inhibited (k_i 380 μM) the oxidative metabolism of aminopyrine. Marked toxicity was observed following incubation of benoxaprofen with isolated hepatocytes from either untreated, phenobarbitone (PB) or 3-methylcholanthrene (3-MC) pretreated male rats. In untreated hepatocytes increases in the intracellular lactate/pyruvate (L/P) ratio and alanine aminotransferase (ALT) release were related to the benoxaprofen concentration and duration of incubation. Alterations in L/P ratio preceded the release of cytosolic ALT and at 4 h a well defined dose-response relationship existed between the benoxaprofen concentration and the observed increases in the L/P ratio and ALT release. Pretreatment of animals with either PB or 3-MC did not affect the temporal nature nor the magnitude of the hepatocyte response to benoxaprofen. In addition, inhibitors of cytochrome P-450 isozymes (SKF-525A, metyrapone and -napthoflavone) were ineffective with regard to modifying the observed toxicity. The results of this study suggest that hepatic cytochrome P-450 mediated metabolism may not be implicated in the toxicity of benoxaprofen in isolated hepatocytes. However, alterations in the cellular redox state and evidence of plasma membrane bleb formation suggest that benoxaprofen may uncouple oxidative phosphorylation and disturb intracellular calcium ion homeostasis.     

Rifampicin exacerbates isoniazid-induced toxicity in human but not in rat hepatocytes in tissue-like cultures

BACKGROUND AND PURPOSE: Rifampicin has been extensively reported to exacerbate the hepatotoxicity of isoniazid in patients with tuberculosis. However, this was controversially claimed by previous reports using rat models. This study evaluated the effect of rifampicin on isoniazid-induced hepatocyte toxicity by using human and rat hepatocytes in tissue-like culture.EXPERIMENTAL APPROACH: Hepatocytes in tissue-like gel entrapment were used to examine isoniazid toxicity, as shown by cell viability, intracellular glutathione content and albumin secretion. For demonstration of the differential effects of rifampicin on human and rat hepatocytes, induction by rifampicin of cytochrome P450 (CYP) 2E1, a major enzyme associated with isoniazid hepatotoxicity, was detected by 4-nitrocatechol formation and RT-PCR analysis.KEY RESULTS: Rifampicin (12 microM) enhanced isoniazid-induced toxicity in human hepatocytes but not in rat hepatocytes. Enhanced CYP 2E1 enzymic activity and mRNA expression were similarly detected in human hepatocytes but not in rat hepatocytes. Both rat and human hepatocytes in gel entrapment were more sensitive to isoniazid treatment compared with the corresponding hepatocytes in a monolayer culture.CONCLUSIONS AND IMPLICATIONS: The difference in induction of CYP 2E1 by rifampicin between rat and human hepatocytes accounted for the difference in exacerbation of isoniazid hepatocyte toxicity by rifampicin, with more significant toxicity in gel entrapment than in monolayer cultures. Thus, human hepatocytes in tissue-like cultures (gel entrapment) could be an effective model for hepatotoxicity research in vitro, closer to the in vivo situation.     

Palmitic acid-induced lipotoxicity and protection by (+)-catechin in rat cortical astrocytes

BackgroundAstrocytes do not only maintain homeostasis of the extracellular milieu of the neurons, but also play an active role in modulating synaptic transmission. Palmitic acid (PA) is a saturated fatty acid which, when being excessive, is a significant risk factor for lipotoxicity. Activation of astrocytes by PA has been shown to cause neuronal inflammation and demyelination. However, direct damage by PA to astrocytes is relatively unexplored. The aim of this study was to identify the mechanism(s) of PA-induced cytotoxicity in rat cortical astrocytes and possible protection by (+)-catechin.MethodsCytotoxicity and endoplasmic reticulum (ER) markers were assessed by MTT assay and Western blotting, respectively. Cytosolic Ca²⁺ and mitochondrial membrane potential (MMP) were measured microfluorimetrically using fura-2 and rhodamine 123, respectively. Intracellular reactive oxygen species (ROS) production was assayed by the indicator 2′-7′-dichlorodihydrofluorescein diacetate.ResultsExposure of astrocytes to 100 μM PA for 24 h resulted in apoptotic cell death. Whilst PA-induced cell death appeared to be unrelated to ER stress and perturbation in cytosolic Ca²⁺ signaling, it was likely a result of ROS production and subsequent MMP collapse, since ascorbic acid (anti-oxidant, 100 μM) prevented PA-induced MMP collapse and cell death. Co-treatment of astrocytes with (+)-catechin (300 μM), an anti-oxidant found abundantly in green tea, significantly prevented PA-induced ROS production, MMP collapse and cell death.ConclusionOur results suggest that PA-induced cytotoxicity in astrocytes may involve ROS generation and MMP collapse, which can be prevented by (+)-catechin.     

漆黄素对脑胶质瘤体外侵袭的抑制作用及其机制

目的：脑胶质瘤是发生率最高的恶性脑肿瘤,因具有高侵袭高浸润性的特点,使其预后效果差,中位生存期只有14.6个月,因此,寻找新的治疗药物或治疗手段意义重大。目前,许多研究发现漆黄素作为一种天然黄酮类化合物具有抗肿瘤作用,对多种肿瘤细胞具有明显抑制作用。然而漆黄素是否作用于脑胶质瘤细胞尚未得到深入探讨。方法：以U-87MG恶性胶质瘤细胞系作为研究对象,利用Transwell侵袭实验和Wound-healing划痕实验检测漆黄素处理后细胞的体外侵袭和迁移能力;利用MTS法检测细胞生长情况,利用流式细胞分析技术检测对漆黄素处理后细胞的细胞周期和细胞凋亡进行分析;利用Western-blot和Real-time PCR技术对相关基因的蛋白和mRNA表达水平进行检测。结果：漆黄素处理后,U-87MG细胞的侵袭力和迁移力显著降低,G₂/M期细胞增多,细胞凋亡显著提高,同时相关基因的表达水平也有明显变化。结论：这些实验结果暗示漆黄素可通过调节细胞周期、促进细胞凋亡而明显降低脑胶质瘤细胞的侵袭和迁移力,从而对脑胶质瘤细胞具有显著的抗肿瘤作用。     

Identification of the major urinary metabolites of (+)-catechin and 3-O-methyl-(+)-catechin in man

Following oral administration of (+)-catechin and 3-O-methyl-(+)-catechin to human volunteers the major urinary metabolites were shown to be the glucuronides of 3'-O-methyl-(+)-catechin respectively. Isolations from urine and from synthetic products have been carried out by semi-preparative high performance liquid chromatography; definitive elucidations of structures have been carried out by gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy.