柿寄生提取物对对乙酰氨基酚诱导小鼠肝损伤的保护作用及作用机制

目的：研究柿寄生提取物对对乙酰氨基酚（APAP）诱导小鼠肝损伤的保护作用及作用机制。方法：将60只健康雄性昆明种小鼠随机分成正常组、模型组、联苯双酯阳性组（150 mg·kg^-1）、柿寄生提取物低、中、高剂量组（11.67，23.34，46.67 mg·kg^-1），灌胃给药8 d后，除正常组外其他各组腹腔注射265 mg·kg^-1对乙酰氨基酚，建立急性肝损伤模型，眼球取血后常规检测血清谷丙转氨酶（ALT）、谷草转氨酶（AST）活性水平、肝匀浆生化指标和肝脏病理。结果：与模型组相比，柿寄生提取物中剂量能明显降低AST、ALT活性水平，降低肿瘤坏死因子-α、白细胞介素-6、白细胞介素-1β表达水平（P<0.05），降低丙二醛活力水平（P<0.05），显著提高超氧化物歧化酶和谷胱甘肽过氧化物酶活性、提高微量还原型谷胱甘肽的水平（P<0.05），改善肝组织病理学变化。结论：柿寄生萃取物能明显减轻APAP所致的肝损伤，其机制与降低炎症因子水平，提高机体抗氧化能力，降低氧化应激有关。     

基于经皮给药研究制川乌与白芍配伍对大鼠皮肤及肝微粒体中CYP450活性的影响

目的：研究经皮给予制川乌-白芍药对后,配伍药对大鼠皮肤、肝脏药物代谢酶的影响,以探讨制川乌-白芍药对的配伍机制。方法：大鼠连续经皮给药制川乌、白芍、制川乌与白芍配伍凝胶剂14 d后,采用探针底物与皮肤、肝微粒体体外孵育,通过高效液相色谱法（HPLC）检测皮肤微粒体中1种探针底物及肝微粒体中4种探针底物的浓度,计算代谢速率,考察各给药组大鼠皮肤、肝微粒体CYP450酶活性的变化。结果：与空白组比较,白芍、制川乌对大鼠皮肤微粒体中的CYP3A4酶具有明显的抑制作用（P<0.05）;与白芍单用组比较,制川乌与白芍配伍给药使大鼠皮肤微粒体中的CYP3A4酶活性显著下降（P<0.05）;与制川乌组比较,制川乌与白芍配伍给药使大鼠皮肤中微粒体的CYP3A4酶的活性显著增加（P<0.05）。与空白组比较,白芍、制川乌对大鼠肝微粒体中的CYP3A4、CYP1A2、CYP2E1、CYP2D6酶都具有明显的抑制作用（P<0.05）;与制川乌组、白芍组比较,制川乌与白芍配伍使大鼠肝微粒体中CYP3A4、CYP1A2、CYP2E1、CYP2D6酶活性均明显增加（P<0.05）。结论：制川乌、白芍均为CYP3A4、CYP1A2、CYP2E1、CYP2D6药酶的抑制剂,两药配伍可引起大鼠皮肤、肝微粒体中药酶活性的改变而致活性成分的代谢速度改变,这可能是制川乌与白芍配伍发挥"增效减毒"的作用机制之一。     

胆石六号颗粒对高脂血症小鼠调脂保肝的作用研究

目的：观察胆石六号颗粒对高脂血症小鼠调脂保肝的作用。方法：将60只小鼠随机分成正常组（K）、模型组（M）、给药组（胆石六号颗粒,D）和阳性对照组（辛伐他汀,Y）,每组15只,采用高脂饮食法建立高脂血症小鼠模型;用试剂盒检测各组小鼠血清天冬氨酸转氨酶（AST）、丙氨酸转氨酶（ALT）、胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）水平;采用比色法检测肝脏组织丙二醛（MDA）含量和超氧化物歧化酶（SOD）活力;肝脏HE染色观察肝组织形态变化。结果：高脂饮食可引起小鼠腹部脂肪堆积,使肝脏明显发生脂肪变性;与正常组相比,模型组小鼠血清转氨酶、TC、TG、LDL-C明显升高（P<0.05）,HDL-C明显降低（P<0.05）;与模型组比较,胆石六号颗粒能明显降低小鼠肝指数,降低血清TC、TG、LDL-C、AST、ALT及肝脏MDA（P<0.01）水平,提高血清HDL-C含量及肝脏SOD活力（P<0.01）,明显改善肝脏组织中脂肪浸润;与阳性对照组比较,胆石六号颗粒组小鼠肝指数,血清TC、TG、LDL-C、AST、ALT、HDL-C,以及肝脏MDA和SOD没有明显差异。结论：胆石六号颗粒对高脂血症小鼠具有调脂保肝作用,有可能作为治疗高脂血症的有效药物。     

维药毛菊苣根-种子不同比例配伍的90%乙醇提取物对小鼠急性肝损伤的保护作用及其机制

目的:研究毛菊苣根-种子药对不同比例配伍90%乙醇提取物的化学指纹谱与肝损伤保护作用的相关性,探索维药处方中"药对"的配伍机制。方法:将毛菊苣的根和种子按6个质量比例 (1:0,0:1,1:1,1:2,1:3,2:1)配伍,用90%乙醇提取,得到6个提取物;观察不同提取物对四氯化碳 (CCl₄)致小鼠急性化学性肝损伤模型,以及小鼠尾静脉注射卡介苗 (BCG)和脂多糖 (LPS)造成急性免疫性肝损伤模型,血清中天冬氨酸氨基转移酶 (AST),丙氨酸氨基转移酶 (ALT)水平的影响及肝脏组织病理改变。采用高效液相色谱法分析各提取物的化学谱图,观察与药效相关的化学物质变化。结果:毛菊苣根-种子以质量比1:2配伍能显著降低CCl₄致小鼠急性化学性肝损伤引起的血清AST (P<0.01)和ALT (P<0.01)升高,对BCG+LPS致急性免疫性肝损伤模型血清中AST (P<0.05)和ALT (P<0.01)也有明显的改善作用;另外,毛菊苣根-种子以质量比1:3配伍对CCl₄致小鼠急性化学性肝损伤引起的血清AST (P<0.01)和ALT (P<0.05)升高,以及对BCG+LPS致急性免疫性肝损伤引起的血清AST (P<0.05)和ALT (P<0.01)升高也有明显的改善作用。化学谱图中的色谱峰与提取物改善CCl₄致小鼠急性化学性肝损伤引起的血清AST和ALT 变化呈正相关。结论:用现代研究方法证实了维药毛菊苣不同药用部位配伍的科学性,进一步从化学角度探索了毛菊苣根-种子肝保护作用的临床经典比例1:2和1:3配伍的可能机制。     

雷公藤甲素致小鼠肝损伤对转运体Mrp2和Oatp2的影响

目的：通过多药耐药相关蛋白2（multidrug resistance protein 2,Mrp2）和有机阴离子转运多肽2（organic anion transporting polypeptides 2,Oatp2）初步探究雷公藤甲素诱导小鼠肝损伤的机制。方法：雄性ICR小鼠单次灌胃给予雷公藤甲素（1.0 mg·kg^-1）24 h后称重,摘眼球采血后分离血清,测定血清生化指标;取肝组织做病理切片;采用免疫印迹法检测肝脏组织中Mrp2和Oatp2的蛋白表达量。结果：与对照组相比,雷公藤甲素组肝重指数显著增加（P<0.05）,部分血清生化指标显著上升（P<0.05）,且肝细胞发生核碎裂和脂肪变性。雷公藤甲素组Oatp2的表达较对照组显著升高了32.79%（P<0.05）,而Mrp2的表达较对照组显著下降了45.47%（P<0.01）。结论：雷公藤甲素可能通过上调肝细胞膜转运体Oatp2和下调Mrp2,扰乱肝内胆红素和胆汁酸代谢排泄平衡,可能是雷公藤甲素诱导肝损伤的机制之一。     

细胞色素P450 2E1在依达拉奉减轻免疫性肝损伤氧化应激中的作用

目的观察细胞色素P450 2E1(CYP 2E1)在依达拉奉作用于刀豆蛋白A(Con A)致小鼠免疫性肝损伤模型中的变化。方法先期给予依达拉奉,之后用Con A腹腔注射致敏小鼠产生急性免疫性肝损伤,观察肝脏病理变化,分光光度法测血清AST和ALT浓度,肝匀浆中SOD、MDA、GSH含量,RT-PCR技术检测肝脏组织CYP 2E1 mRNA水平,Westernblot技术检测肝脏组织CYP 2E1蛋白表达水平。结果与模型组比较,依达拉奉能降低免疫性肝损伤小鼠血清中升高的ALT、AST含量;降低肝匀浆中的MDA水平,升高其降低的SOD、GSH水平;CYP 2E1 mRNA水平明显降低,CYP 2E1蛋白表达水平明显下调。结论依达拉奉对小鼠急性免疫性肝损伤具有一定的保护作用,这可能与它降低CYP 2E1的表达,清除自由基,增强机体抗脂质过氧化能力有关。     

白藜芦醇对焦虑模型小鼠行为的改善及对氧化应激因子的影响

目的：观察白藜芦醇对氧化应激小鼠焦虑样行为的改善作用及对其体内氧化应激因子的影响。方法：将小鼠随机分为正常组、模型组和给药组,给予小鼠L-丁硫氨酸-亚砜亚胺（BSO）造模后分别给予不同剂量白藜芦醇（10,20,40,80 mg·kg^-1）,采用明暗箱行为学实验观察药物对小鼠焦虑样行为的影响,通过检测小鼠杏仁核及海马中氧化应激相关因子SOD及MDA水平,采用Western blot检测小鼠杏仁核以及海马中NADPH氧化酶亚基gp91phox的表达变化来研究白藜芦醇抗焦虑作用与氧化应激的关系。结果：行为学实验结果显示,给予白藜芦醇（80 mg·kg^-1）48 h后能明显改善BSO引起的焦虑样行为,主要表现在明暗箱实验中小鼠穿梭明暗箱次数增多（P<0.05）以及停留在明箱中时间比变大（P<0.01）,给予白藜芦醇（40,80 mg·kg^-1）小鼠杏仁核（P<0.01,P<0.01）及海马中SOD活力明显增加（P<0.05,P<0.01）,此外给予白藜芦醇（40,80 mg·kg^-1）小鼠杏仁核（P<0.01,P<0.01）及海马中（P<0.05,P<0.01）MAD含量明显减少。Western blot实验结果显示给予白藜芦醇（20,40,80 mg·kg^-1）能明显降低BSO引起的杏仁核gp91phox表达增加（P<0.05,P<0.01,P<0.01）,同时给予白藜芦醇（20,40,80 mg·kg^-1）能明显降低海马中gp91phox表达（P<0.05,P<0.01,P<0.01）。结论：白藜芦醇能逆转氧化应激引起的小鼠焦虑样行为,其机制可能和其改善小鼠体内氧化应激能力有关。     

热休克预处理对对乙酰氨基酚所致小鼠急性肝损伤的保护作用

目的探讨热休克预处理对对乙酰氨基酚(AAP)诱导的小鼠急性肝损伤的保护作用。方法40℃分别热休克(HS)处理小鼠10min(HS10组)、20min(HS20组)和30min(HS30组),室温恢复8h后,小鼠ip给予AAP 550mg·kg-1诱导急性肝损伤,分别于AAP后0,6,24,42和72h进行相关指标检测。赖氏法检测小鼠血清中天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性,HE染色进行病理学分析,免疫组化法检测给予AAP后0 h,小鼠肝热休克蛋白70(HSP70),细胞色素P4501A2(CYP1A2)和增殖细胞核抗原(PCNA)的表达,Western印迹法检测给予AAP后0,6,24,42和72h时小鼠PCNA的表达。结果与AAP对照组相比,HS20组小鼠血清中AST和ALT酶活水平显著降低(P<0.05),而HS10组和HS30组小鼠无显著差异。与AAP对照组相比,HS20显著降低了AAP诱导的小鼠肝损伤程度(P<0.05),而HS10和HS30未显著降低肝损伤的程度。HS20显著诱导了小鼠肝HSP70(P<0.01),CYP1A2(P<0.01)和PCNA(P<0.05)的表达,而HS10和HS30显著诱导了小鼠肝HSP70和CYP1A2(P<0.05)的表达,但未明显诱导PCNA的表达。与HS10和HS30相比,HS20更加显著地诱导了HSP70和CYP1A2的表达(P<0.05)。HS20组小鼠在注射AAP后0,6,24,42和72h,小鼠肝PCNA的表达均显著高于AAP对照组(P<0.05)、HS10和HS30组(P<0.05)。结论 40℃热休克预处理20min可以有效降低AAP诱导的小鼠急性肝损伤程度,加速肝损伤后的修复。     

异型南五味子醇提物对D-半乳糖胺/脂多糖致小鼠急性肝损伤的保护作用

目的：研究异型南五味子对D-半乳糖胺/脂多糖诱导小鼠肝损伤的保护作用。方法：ICR小鼠按体质量随机分为 6组,即正常组、模型组、联苯双酯（200 mg·kg^-1）组,异型南五味子醇提物低、中、高剂量（200、400、800 mg·kg^-1）组。每天给药一次,连续给药14 d,末次给药1 h后,除正常组外其余各组用600 mg·kg^-1 D-半乳糖胺和40 μg·kg^-1脂多糖腹腔注射以复制小鼠急性肝损伤模型,末次给药12 h后,摘眼球取血,取材。用生化法测定血清中ALT、AST水平,用酶联免疫法测定各组小鼠肝匀浆中SOD、MDA、MPO及GPx-2含量,测定血清及肝组织中 TNF-α、IL-6、IL-10炎性因子表达水平,并于光镜下检查肝组织病理变化。结果：与模型组比较,异型南五味子200、400、800 mg·kg^-1剂量均能显著降低血清中ALT、AST水平（P<0.05或P<0.01）,明显降低肝匀浆中MDA、MPO含量,显著升高SOD、GPx-2水平（P<0.05或P<0.01）,并能降低肝脏及血清中TNF-α、IL-6含量,升高IL-10的表达水平（P<0.05或P<0.01）。病理观察显示异型南五味子组能明显减轻肝脏灶性坏死、水肿,减少肝脏炎性细胞浸润。结论：异型南五味子对腹腔注射600 mg·kg^-1D-半乳糖胺和40 μg·kg^-1脂多糖诱导的小鼠急性肝损伤具有较好的保护作用。     

白及多糖对小鼠急性酒精性肝损伤的保护作用

目的: 探讨白及多糖(BSPS)对小鼠急性酒精性肝损伤的保护作用及其作用机制。方法: 以健康雄性昆明小鼠60只随机分为正常对照组、 酒精性肝损伤模型对照组、阳性对照组(水飞蓟素组)、BSPS低、中、高剂量组。用50%酒精灌胃,建立小鼠急性酒精性肝损伤模型。检测肝组织中丙氨酸氨基转移酶(ALT)活性、三酰甘油(TG)、超氧化物歧化酶(SOD)和谷胱甘肽(GSH)含量,并观察肝组织病理形态学变化。结果: 与模型对照组相比,BSPS中、高剂量组肝组织中ALT和TG含量明显降低(P<0.01,P<0.05),BSPS低、中、高剂量组肝组织中SOD含量明显增高(P<0.01,P<0.05),BSPS高剂量组肝组织中GSH含量明显增高(P<0.01)。小鼠肝组织形态学研究结果显示,BSPS不同剂量组对酒精性肝损伤均有一定的保护作用,以高剂量组效果最好。结论: BSPS通过减轻肝脏氧化损伤以及脂质沉积来改善酒精对肝脏的损伤,其保护作用呈现一定剂量依赖性。     

Role of CYP3A and CYP2E1 in alcohol-mediated increases in acetaminophen hepatotoxicity: comparison of wild-type and Cyp2e1(-/-) mice.

CYP2E1 is widely accepted as the sole form of cytochrome P450 responsible for alcohol-mediated increases in acetaminophen (APAP) hepatotoxicity. However, we previously found that alcohol [ethanol and isopentanol (EIP)] causes increases in APAP hepatotoxicity in Cyp2e1(-/-) mice, indicating that CYP2E1 is not essential. Here, using wild-type and Cyp2e1(-/-) mice, we investigated the relative roles of CYP2E1 and CYP3A in EIP-mediated increases in APAP hepatotoxicity. We found that EIP-mediated increases in APAP hepatotoxicity occurred at lower APAP doses in wild-type mice (300 mg/kg) than in Cyp2e1(-/-) mice (600 mg/kg). Although this result suggests that CYP2E1 has a role in the different susceptibilities of these mouse lines, our findings that EIP-mediated increases in CYP3A activities were greater in wild-type mice compared with Cyp2e1(-/-) mice raises the possibility that differential increases in CYP3A may also contribute to the greater APAP sensitivity in EIP-pretreated wild-type mice. At the time of APAP administration, which followed an 11 h withdrawal from the alcohols, alcohol-induced levels of CYP3A were sustained in both mouse lines, whereas CYP2E1 was decreased to constitutive levels in wild-type mice. The CYP3A inhibitor triacetyloleandomycin (TAO) decreased APAP hepatotoxicity in EIP-pretreated wild-type and Cyp2e1(-/-) mice. TAO treatment in vivo resulted in inhibition of microsomal CYP3A-catalyzed activity, measured in vitro, with no inhibition of CYP1A2 and CYP2E1 activities. In conclusion, these findings suggest that both CYP3A and CYP2E1 contribute to APAP hepatotoxicity in alcohol-treated mice.     

辣木叶及辣木籽对大鼠CYP450酶3种亚型基因表达影响

目的:研究辣木叶及辣木籽对大鼠肝脏CYP450亚型酶中mRNA及蛋白表达量的影响。方法:将SD大鼠随机分为空白组(0.5%羧甲基纤维素钠混悬溶液)、辣木叶高、中、低剂量组(分别为0.813 8,0.406 9,0.203 5g·kg^-1);辣木籽高、中、低剂量组(分别为1.067 4,0.533 7,0.266 9g·kg^-1)。灌胃给药,给药容量为10mL·kg^-1,2次/天,连续给药14d,取大鼠肝脏,采用实时荧光定量PCR(RT-qPCR)及蛋白免疫印迹(Western-blot)法检测大鼠肝脏中CYP2E1、CYP3A1及CYP1A2的mRNA及蛋白相对表达量。结果:辣木叶高剂量组对CYP2E1的mRNA表达有明显抑制作用(P<0.05);在(0.813 8±0.203 5)g·kg^-1剂量范围内,辣木叶对CYP1A2mRNA表达的抑制作用随给药剂量增加而增加(P<0.05)。本实验剂量范围内的辣木籽对3个酶的mRNA表达都有明显的抑制作用(P<0.05),其抑制效率CYP2E1>CYP3A1>CYP1A2。高剂量组辣木叶及辣木籽对CYP2E1蛋白表达都有明显抑制作用(P<0.01);中、低剂量组的辣木籽对CYP3A1及CYP1A2蛋白表达都有不同程度的抑制作用(P<0.05;P<0.05);中剂量辣木叶对CYP1A2蛋白表达抑制作用显著(P<0.01)。结论:辣木叶及辣木籽对大鼠肝脏中3个亚型酶的mRNA及蛋白表达都有不同程度的抑制作用。     

CYP2E1 and miRNA‐378a‐3p contribute to acetaminophen‐ or tripterygium glycosides‐induced hepatotoxicity

Increased expression of CYP2E1 may represent the main factor contributing to oxidative stress‐mediated liver damage in drug‐induced liver injury (DILI). However, the regulation mechanism of CYP2E1 expression is poorly described. The present study was aimed to investigate the role of CYP2E1 in acetaminophen (APAP)‐ or tripterygium glycosides (TG)‐induced hepatotoxicity as well as the regulation of CYP2E1 and miR‐378a‐3p expression by APAP or TG. Rats were randomly divided and treated with APAP, TG, chlormethiazole (CMZ), APAP + CMZ and TG + CMZ, respectively, for 4 weeks. Then, blood and liver samples were collected. Serum and hepatic biochemical parameters were measured using commercial kits. Liver histopathology was tested by H&E staining. Expression levels of CYP2E1 mRNA and miR‐378a‐3p were detected by qRT‐PCR. CYP2E1 protein expression was determined by Western blot. Our results showed that CMZ effectively restored the hepatic histopathological changes, oxidative stress biomarkers and TNF‐α levels induced by APAP or TG. CYP2E1 mRNA and/or protein expression levels were dramatically increased after chronic APAP or TG treatment, while this induction was significantly reversed by CMZ co‐treatment. Of note, miR‐378a‐3p expression levels were significantly suppressed after APAP, TG and/or CMZ treatment. These results suggested that CYP2E1 were highly induced after chronic APAP or TG treatment, which in turn play an important role in APAP‐ or TG‐induced hepatotoxicity. These inductions of CYP2E1 expression were probably carried out by inhibition of miR‐378a‐3p. Our findings might provide a new molecular basis for DILI.     

川芎嗪对小鼠颅脑损伤后大脑组织细胞凋亡相关因子的影响

目的:研究川芎嗪对小鼠颅脑损伤(CI)后的细胞凋亡通路中相关蛋白及其mRNA的影响,揭示川芎嗪治疗颅脑损伤的可能作用机制。方法:将50只昆明种小鼠,随机分成假手术组、模型组、川芎嗪治疗组(40,80,160 mg·kg^-1)五组,采用改良的Feeney自由落体损伤装置建立小鼠CI模型。造模3 d后开始灌胃治疗,每日1次,其他各组给予等量生理盐水,连续用药20 d;蛋白免疫印迹和RT-PCR技术分别检测小鼠大脑组织中凋亡相关蛋白及其mRNA(Bax、Bcl-2、Caspase-9和Caspase-3)的表达量。结果:与假手术组相比,模型组小鼠大脑的凋亡蛋白Bax、Caspase-3和Caspase-9及其mRNA表达增加,差异极显著(P<0.01,P<0.01,P<0.01),抗凋亡蛋白Bcl-2及其mRNA表达差异无统计学意义(P>0.05);与模型组相比,治疗组大脑凋亡蛋白Bax、Caspase-3和Caspase-9及其mRNA表达降低,差异极显著(P<0.01,P<0.01,P<0.01),抗凋亡蛋白Bcl-2及其mRNA表达增加,差异极显著(P<0.01)。结论:川芎嗪可能通过上调Bcl-2蛋白及其mRNA的表达,抑制Bax、Caspase-3和Caspase-9蛋白及其mRNA的表达,减少大脑组织细胞凋亡,保护大脑组织。     

湖北巴戟天对D-半乳糖所致衰老模型小鼠的抗衰老作用

目的：研究湖北巴戟天是否对D-半乳糖所致衰老模型小鼠具有抗衰老作用。方法：60只昆明种雄性小鼠随机分成6组,分别为正常组,模型组,维生素E（VitE）阳性对照组（100 mg·kg^-1·d^-1）和湖北巴戟天醇提物低、中、高3个剂量组（15,30,45 mg·kg^-1·d^-1）。除正常组颈背部皮下注射等体积生理盐水外,其余各组颈背部皮下注射D-半乳糖（150 mg·kg^-1·d^-1）建立衰老模型,为期60 d。统计各组小鼠在跳台和Morris水迷宫实验中错误次数或穿越次数,计算各组小鼠的脏器指数,测量血清及脑组织中SOD、CAT、GSH-Px活力和MDA含量,并测定各组小鼠脑细胞凋亡指数。结果：湖北巴戟天醇提物3个剂量组均能减少跳台错误次数（P<0.05或P<0.01）,增加水迷宫穿越次数（P<0.05或P<0.01）;升高小鼠血清及脑组织中SOD、CAT、GSH-Px活力（P<0.01）,降低MDA含量（P<0.05）;提高衰老小鼠脑、胸腺、脾脏和睾丸及附睾指数（P<0.05或P<0.01）,减少细胞凋亡（P<0.01）,呈剂量依赖性。结论：湖北巴戟天对D-半乳糖所致衰老模型小鼠具有较好的抗衰老作用。     

Type 1 diabetic mice are protected from acetaminophen hepatotoxicity.

Streptozotocin (STZ)-induced diabetic (DB) mice challenged with single ordinarily lethal doses of acetaminophen (APAP), carbon tetrachloride (CCl4), or bromobenzene (BB) were resistant to all three hepatotoxicants. Mechanisms of protection against APAP hepatotoxicity were investigated. Plasma alanine aminotransferase, aspartate aminotransferase, and liver histopathology revealed significantly lower hepatic injury in DB mice after APAP administration. HPLC analysis of plasma and urine revealed lower plasma t1/2, increased volume of distribution (Vd), and increased plasma clearance (CLp) of APAP in the DB mice and no difference in APAP-glucuronide, a major metabolite in mice. Interestingly, covalent binding of 14C-labeled APAP to liver target proteins; arylation of APAP to 58, 56, and 44 kDa acetaminophen binding proteins (ABPs); and glutathione (GSH) depletion in the liver did not differ between nondiabetic (non-DB) and DB mice in spite of downregulated hepatic microsomal CYP2E1 and 1A2 proteins in the DB mice, known to be involved in bioactivation of APAP. Compensatory cell division measured via 3H-thymidine pulse labeling and immunohistochemical staining for proliferating cell nuclear antigen (PCNA) indicated earlier onset of S-phase in the DB mice after exposure to APAP. Antimitotic intervention of liver cell division by colchicine (CLC) after administration of APAP led to significantly higher mortality in the DB mice suggesting a pivotal role of liver cell division and tissue repair in the protection afforded by diabetes. In conclusion, the resistance of DB mice against hepatotoxic and lethal effects of APAP appears to be mediated by a combination of enhanced APAP clearance and robust compensatory tissue repair.     

Nonalcoholic steatohepatitic (NASH) mice are protected from higher hepatotoxicity of acetaminophen upon induction of PPARalpha with clofibrate

The objective was to investigate if the hepatotoxic sensitivity in nonalcoholic steatohepatitic mice to acetaminophen (APAP) is due to downregulation of nuclear receptor PPARalpha via lower cell division and tissue repair. Male Swiss Webster mice fed methionine and choline deficient diet for 31 days exhibited NASH. On the 32nd day, a marginally toxic dose of APAP (360 mg/kg, ip) yielded 70% mortality in steatohepatitic mice, while all non steatohepatitic mice receiving the same dose survived. (14)C-APAP covalent binding, CYP2E1 protein, and enzyme activity did not differ from the controls, obviating increased APAP bioactivation as the cause of amplified APAP hepatotoxicity. Liver injury progressed only in steatohepatitic livers between 6 and 24 h. Cell division and tissue repair assessed by (3)H-thymidine incorporation and PCNA were inhibited only in the steatohepatitic mice given APAP suggesting that higher sensitivity of NASH liver to APAP-induced hepatotoxicity was due to lower tissue repair. The hypothesis that impeded liver tissue repair in steatohepatitic mice was due to downregulation of PPARalpha was tested. PPARalpha was downregulated in NASH. To investigate whether downregulation of PPARalpha in NASH is the critical mechanism of compromised liver tissue repair, PPARalpha was induced in steatohepatitic mice with clofibrate (250 mg/kg for 3 days, ip) before injecting APAP. All clofibrate pretreated steatohepatitic mice receiving APAP exhibited lower liver injury, which did not progress and the mice survived. The protection was not due to lower bioactivation of APAP but due to higher liver tissue repair. These findings suggest that inadequate PPARalpha expression in steatohepatitic mice sensitizes them to APAP hepatotoxicity.