Pretreatment with 1,8-cineole potentiates thioacetamide-lnduced hepatotoxicity and immunosuppression

The effect of 1,8-cineole on cytochrome P450 (CYP) expression was investigated in male Sprague Dawley rats and female BALB/c mice. When rats were treated orally with 200, 400 and 800 mg/kg of 1,8-cineole for 3 consecutive days, the liver microsomal activities of benzyloxyresorufin- and pentoxyresorufin-omicron-dealkylases and erythromycin N-demethylase were dose-dependently induced. The Western immunoblotting analyses clearly indicated the induction of CYP 2B1/2 and CYP 3A1/2 proteins by 1,8-cineole. At the doses employed, 1,8-cineole did not cause toxicity, including hepatotoxicity. Subsequently, 1,8-cineole was applied to study the role of metabolic activation in thioacetamide-induced hepatotoxicity and/or immunotoxicity in animal models. To investigate a possible role of metabolic activation by CYP enzymes in thioacetamide-induced hepatotoxicity, rats were pre-treated with 800 mg/kg of 1 ,8-cineole for 3 days, followed by a single intraperitoneal treatment with 50 and 100 mg/kg of thioacetamide in saline. 24 h later, thioacetamide-induced hepatotoxicity was significantly potentiated by the pretreatment with 1,8-cineole. When female BALB/c mice were pretreated with 800 mg/kg of 1,8-cineole for 3 days, followed by a single intraperitoneal treatment with 100 mg/kg of thioacetamide, the antibody response to sheep red blood cells was significantly potentiated. In addition, the liver microsomal activities of CYP 2B enzymes were significantly induced by 1,8-cineole as in rats. Taken together, our results indicated that 1,8-cineole might be a useful CYP modulator in investigating the possible role of metabolic activation in chemical-induced hepatotoxicity and immunotoxicity.     

The antihepatotoxic activity of dithiocarb as compared with six other thio compounds in mice

In mice, diethyldithiocarbamate (dithiocarb, 100 mg/kg i.p.) completely prevented the increments of serum enzyme activities (GOT, GPT, SDH) induced by oral administration of carbon tetrachloride (0.1 ml/kg), allyl alcohol (0.05 ml/kg), bromobenzene (0.25 ml/kg), and thioacetamide (50 mg/kg). In this respect, cysteine (200 mg/kg i.p.) was active against CCl₄ and bromobenzene, cysteamine (100 mg/kg i.p.) against CCl₄ and allyl alcohol, penicillamine (100 mg/kg i.p.) against allyl alcohol, thiazolidine carbonic acid (100 mg/kg i.p.) against bromobenzene, and thioctic acid (100 mg/kg i.p.) against allyl alcohol and thioacetamide. Dimercaprol (100 mg/kg i.p.) had a weak antidotal effect only against allyl alcohol poisoning. None of the tested antidotes inhibited serum enzyme elevations evoked by dimethyl nitrosamine (100 mg/kg p.o.). These findings prove the antihepatotoxic activity of diethyldithiocarbamate to be superior to that of all other thio compounds under observation.The lowest dose of dithiocarb active against carbon tetrachloride was 25 mg/kg i.p. The dose-response curves for serum-enzyme elevations induced by carbon tetrachloride (0.1–4 ml/kg p.o.) were shifted to the right under the influence of dithiocarb indicating a competitive antagonism. Dithiocarb (100 mg/kg i.p.) depressed the p-hydroxylation of aniline in the 9000 x g liver homogenate supernatant of mice by about 55%. Thus, the antihepatotoxic activity of dithiocarb seems to be the consequence of a decreased oxidase activity.     

山莨菪碱对肝细胞损伤的治疗作用及机制

目的　探讨山莨菪碱 (6 5 4 2 )对急性肝细胞损伤的治疗作用及作用机制。方法　以硫代乙酰胺 (TAA)损伤体外培养的SD乳鼠肝细胞为模型 ,用 6 5 4 2处理损伤组 ,观察正常对照组、TAA组、6 5 4 2组肝细胞的活性 ,培养液中乳酸脱氢酶 (LDH)、超氧化物歧化酶 (SOD)和一氧化氮(NO)含量的变化。结果　 6 5 4 2组肝细胞活性及培养液中SOD(2 6 0 3± 0 43NU/ml)、NO(82 7 83± 44 46 μM )明显高于TAA组肝细胞活性及培养液中SOD(17 40± 0 41NU/ml)、NO(743 30±2 5 6 0 μM )。 6 5 4 2组培养液中LDH(2 6 4 0 0± 2 1 35U/ 10 0ml) ,明显低于TAA组 (386 5 0± 6 9 93U/10 0ml)。结论　 6 5 4 2对TAA损伤肝细胞有治疗作用 ,治疗作用可能与 6 5 4 2的生物膜保护、清除自由基、改善微循环有关。     

Prehepatic portal hypertension worsens the enterohepatic redox balance in thioacetamide-cirrhotic rats

Background: Oxidative stress has been reported as a key pathogenic factor in many human liver diseases and in experimental models of cirrhosis related to hepatotoxin administration. The aim of this study was to verify the hypothesis that prehepatic portal hypertension aggravates the enterohepatic redox imbalance in thioacetamide-cirrhotic rats. Materials and methods: Wistar male rats were used: Control (n = 9); rats with prehepatic portal hypertension by triple partial portal vein ligation (TPVL; n = 9); thioacetamide-cirrhotic rats (TAA; n = 9) and TPVL-rats associated to TAA administration (TPVL + TAA; n = 9). Three months after the operation, portal pressure (PP), mesenteric venous vasculopathy (MVV) and portosystemic collateral circulation were studied. Liver and ileal levels of malondialdehyde (MDA), as a lipid peroxidation marker, and catalase (CAT), glutathione peroxidase (GSH-Px), glutathione transferase (GSH-t) and cytosolic and mitochondrial superoxide dismutases (cSOD and mSOD), as antioxidative enzymatic mechanisms, were measured. Results: Liver and ileal MDA increased in all the experimental groups, although the higher increase occurred in the ileum of rats with portal hypertension. CAT levels decreased in the liver and the ileum in the three experimental groups. The decrease in liver and ileal GSH-Px and GSH-t was greater in rats with portal hypertension, alone or associated with TAA. mSOD activation was demonstrated in the liver when portal hypertension was added to TAA. On the contrary, this compensatory response was not activated in the ileum, where mSOD was significantly decreased. Conclusion: Prehepatic portal hypertension by triple partial portal vein ligation impaired the enterohepatic antioxidative activity and aggravated the intestinal oxidative stress in thioacetamide-cirrhotic rats.     

Reversible decrease of dopamine D2 receptor density in the striatum of rats with acute hepatic failure

The binding of a D2 receptor ligand, [3H]spiperone, was measured in striatal membranes derived from rats in which acute hepatic failure induced with thioacetamide (TAA) was associated with symptoms of hepatic encephalopathy (HE), and during recovery from HE. A 28% decrease of Bmax for the binding was measured in a symptomatic stage of HE, 1 day after TAA administration. The B(max) for [3H]spiperone binding was no longer different from control 7 days after TAA administration, when blood and brain biochemical correlates of HE were already absent. At 21 days after TAA administration, the B(max) was increased by 31% above the control level, consistent with other aspects of metabolic activation of the brain characteristic of the late recovery period from acute HE.     

Co-administration of cyclosporine A alleviates thioacetamide-induced liver injury

AIM: To investigate the effects of cyclosporine A (CsA) on thioacetamide (TAA)-induced liver injury. METHODS: CsA was co-administrated (7.5 μg/kg body weight per day, i.p.) into rat to investigate the role of CsA on TAA-(200 mg/kg body weight per 3 d for 30 d, i.p.) induced liver injury. RESULTS: The data show that TAA caused liver fibrosis in rat after 30 d of treatment. CsA alleviates the morphological changes of TAA-induced fibrosis in rat liver. The blood glutamyl oxaloacetic transaminase (GOT)/glutamyl pyruvic transaminase (GPT) in the TAA-injury group is elevated compared to that of the normal rat. Compared with the TAA-injury group, the blood GOT/GPT and TGFβ1(by RT-PCR analysis) are reduced in the CsA plus TAA-treated rat. The level of the transforming growth factor receptor I (TGFβ-R1) in the CsA plus TAA-treated group shows higher than that in the TAA only group, but shows a lower level of the fibroblast growth factor receptor 4 (FGFR4) in the CsA plus TAA-treated group, when using the Western blot analysis. After immunostaining of the frozen section, TGFβ-R1 and FGFR4 are more concentrated in rat liver after CsA plus TAA injury. CONCLUSION: This result suggests that CsA has an alleviated effect on TAA-induced liver injury by increasing the multidrug resistance P-glycoprotein and could be through the regulation of TGFβ-R1 and FGFR4.     

Acetylcholinesterase activity in an experimental rat model of Type C hepatic encephalopathy

Patients with liver malfunction often suffer from hepatic encephalopathy, a neurological complication which can affect attention and cognition. Diverse experimental models have been used to study brain alterations that may be responsible for hepatic encephalopathy symptoms. The aim of the study was to determine whether cognitive impairment found in cirrhosis could be due to disturbance of acetylcholinesterase activity. Acetylcholinesterase activity was assessed in the brains of Wistar rats with thioacetamide-induced cirrhosis. The cirrhotic group displayed up-regulation of acetylcholinesterase levels in the entorrhinal cortex, anterodorsal and anteroventral thalamus and accumbens, whereas down-regulation was found in the CA1, CA3 and dentate gyrus of the hippocampus. Our results indicate that the experimental model of hepatic encephalopathy by chronic administration of thioacetamide presents alterations of acetylcholinesterase activity in brain limbic system regions, which play a role in attention and memory.     

四氯化碳、硫代乙酰胺和猪血清诱导大鼠肝纤维化模型的比较

目的：比较采用四氯化碳（CCl4）,硫代乙酰胺（TAA）及猪血清诱导3种方式制备大鼠肝纤维化模型的效果和特点。方法：将72只SD大鼠随机均分为：CCl4组,TAA组,猪血清组及对照组,分别每周2次皮下注射40% CCl4（0.5 mL/100 g）,0.03% TAA（200 mg/kg）,猪血清（0.5 mL/只）和生理盐水（0.1 mL/kg）。观察大鼠一般情况及体重变化;在造模第3,6,9周末,测定大鼠血清中的天冬氨酸氨基转移酶（AST）,谷氨酸氨基转移酶（ALT）,丙二醛（MDA）,透明质酸（HA）水平;取肝组织进行HE染色,观察肝组织结构变化,并对肝纤维化程度进行分级和评分。结果：CCl4,TAA组大鼠体重增加量均明显低于对照组（均P<0.05）,而猪血清组与对照组间体重增加量差异无统计学意义（P>0.05）;TAA组3个时间点ALT浓度均明显升高（均P<0.05）,而CCl4组和猪血清组ALT无明显升高。CCl4组AST浓度在第3周明显升高（P<0.05）,但在第6,9周有所下降,TAA组3个时间点AST浓度均明显升高（均P<0.05）,猪血清组AST浓度无明显升高。3个实验组MDA和HA浓度在3个时点间均有所升高（均P<0.05）,两者均在TAA组升高最明显;3个实验组第9周均可见不同程度的肝细胞颗粒样变,汇管区纤维组织异常增生;与对照组比较,3个实验组的肝纤维化分级和SSS计分差异均具有统计学意义（均P<0.05）,第9周时,TAA组的SSS计分高于CCl4组（P<0.05）,而CCl4组的SSS评分高于猪血清组（P<0.05）。结论：3种方法均可诱导大鼠肝纤维化模型,TAA效果略优于CCl4。猪血清法造模对动物整体损伤较轻微。     

丹参在硫代乙酰胺诱导大鼠肝纤维化过程中的作用

目的 探讨丹参(Radix saliviae miltiorrizae,RSM)在肝纤维化过程中的作用。方法 采用大鼠腹腔注射硫代乙酰胺(TAA),复制肝纤维化模型。分别给不同组大鼠腹腔注射TAA和皮下注射丹参,13周后观察谷丙氨酸转氨酶(ALT)、乳酸脱氢酶(LDH)、血浆内毒素LPs含量、血浆和肝组织NO含量、HE和V·G染色观察各组肝组织形态改变。结果 TAA组:ALT、LDH、LPS羟脯氨酸、血浆和肝组织NO含量均高于正常对照组(P<0.05),丹参组上述指标均低于TAA组,组织学观察丹参组肝损伤和纤维化程度较TAA组轻。结论 丹参在TAA诱导的肝纤维化过程中有保护作用。     

岗松挥发油对实验性肝损害的防治作用

本研究表明,岗松油对四氯化碳、硫代乙酰胺、醋酸强的松龙引起的小鼠SGPT升高有明显的降低作用,使BSP潴留量减少,相应肝组织病变减轻。此外,岗松油对四氯化碳损害小鼠和正常小鼠戊巴比妥钠的睡眠时间均能明显缩短。对巴豆油引起小鼠耳部炎症有明显的抗炎作用。岗松油的毒性很低,口服半数致死量(LD₅₀为3,758±539mg/kg,给兔灌胃687～1030mg/kg每天一次,连续30天,一般表现、血象、肝肾功能及病理检查均未见明显的改变。