Early destruction of cytochrome P-450 in testis of carbon tetrachloride poisoned rats

There is 20--36 percent decrease in the microsomal cytochrome P-450 (P450) content of the testes 3 or 6 h after CCl4 administration to Sprague--Dawley male rats. Irreversible binding of CCl4 metabolites to testicular microsomal lipids is observed as early as 3 h while CCl4 induced lipid peroxidation does not occur within the first 6 h of poisoning. Results suggest that reactive metabolites rather than lipid peroxidation is involved in P-450 destruction in the testes.     

Effects of carbon tetrachloride on the liver of chickens. Early biochemical and ultrastructural alterations in the absence of detectable lipid peroxidation

Administration of CCl4 i.p. to Leghorn chickens did not promote lipid peroxidation of liver microsomal lipids, as evidenced by either increased diene conjugation or by decreased arachidonic acid content. The hepatotoxin did not produce liver necrosis 24 h after dosing, but decreased the cytochrome P-450 content, and aminopyrine N-demethylase and glucose 6 phosphatase activities at 1, 3, 6 and 24 h. CCl4 administration produced dilation of the rough endoplasmic reticulum and detachment of ribosomes from their membranes. These observations suggest that lipid peroxidation is not the key event in the production of these biochemical and ultrastructural alterations, elicited by CCl4.     

Biochemical aspects of the protective action of propyl gallate on liver injury in rats poisoned with carbon tetrachloride.

Liver injury in rats intoxicated with a high dose of CCl₄ (2.5 ml/kg, po) is partially prevented by propyl gallate. The accumulation of hepatic triglycerides and the release of liver enzymes into the plasma are more effectively inhibited by this antioxidant in rats given a smaller dose of the hepatotoxin (0.25 ml/kg, po). The antioxidant activity of propyl gallate, administered in vivo, estimated by means of the production of malonyl dialdehyde in liver homogenates in vitro, has been found to decrease progressively after treatment. The concentration of nonesterified fatty acids in the serum is not affected by dosing with propyl gallate. However, propyl gallate releases the block in triglyceride secretion from the liver that occurs after administration of CCl₄. Furthermore, both the uptake of CCl₄ by the liver and the early steps of the free radical reaction (incorporation of labeled metabolites of ¹⁴CCl₄ and double bond shifting in microsomal unsaturated lipids) are unchanged by concomitant dosing with propyl gallate. This free radical scavenger, when administered in discrete doses, more markedly influences both CCl₄ liver damage and the efficiency of the hepatic drug metabolizing enzyme system. This effect in vivo is consistent with the reported in vitro interaction of propyl gallate with microsomal electron transport. These findings indicate that propyl gallate partially interferes with the enzymes bound to the endoplasmic reticulum, but affects the secondary phenomena of lipid peroxidation at the level where lipoproteins are secreted and/or the permeability of plasma membrane is altered.     

Studies on the mechanism of cystamine prevention of several liver structural and biochemical alterations caused by carbon tetrachloride

Cystamine and cysteamine give type II spectral changes by interaction with microsomal suspensions while CCl₄ gives a type I spectral change. Neither cystamine nor cysteamine at saturating concentrations prevent the spectral binding of small amounts of CCl₄. Cystamine and cysteamine decelerate the reduction of cytochrome P-450 by cytochrome P-450 reductase. Cystamine administration partially prevents the irreversible binding of ¹⁴CCl₄ to microsomal lipids. This preventive effect does not significantly change when the ¹⁴CCl₄ dose is increased about 4-fold. In spite of the fact that this irreversible binding is decreased by about 60% at 6 hr by the previous cystamine administration, lipid peroxidation is only slightly prevented at 6 and 10 hr after CCl₄ and prevented to about 30% at 24 hr. Cystamine partially prevented the depression of glucose-6-phosphatase activity and the destruction of cytochrome P-450 caused by CCl₄. Cystamine pronouncedly lowers body temperature of the rats, and it is as effective in preventing CCl₄-induced necrosis and fatty liver at 24 hr as it is at 48 or 72 hr after CCl₄ administration. Cystamine stabilizes lysosomes in vitro but labilizes them when administered to rats. Cysteamine labilizes lysosomes in vitro. These results may suggest that cystamine administration partially prevents several structural and biochemical alterations caused by CCl₄ because it inhibits the CCl₄-activation step to ·CCl₃ free radical, which would take place during the reduction of the cytochrome $\text{P-450}\text{CCl}{}_4$ complex by cytochrome P-450 reductase.     

Interaction of carbon tetrachloride and progesterone metabolism in liver microsomes from triacetyloleandomycin-treated rats

The production of progesterone metabolites by rat liver microsomes from TAO-treated rats was investigated. More than ten metabolites could be identified, including various dihydroxy-progesterones. CCl₄ co-incubation modifies the P-450-dependent progesterone metabolite profile in a remarkable fashion without production of CCl₄ progesterone adducts.Dedicated to Professor Dr. med. Herbert Remmer on the occasion of his 65th birthday     

Carbon tetrachloride induced liver alterations in rats pretreated with N,N'-diphenyl-p-phenylenediamine

Glucose-6-phosphatase (G6P-ase) activity of liver microsomes was decreased 15 min following carbon tetrachloride administration, but it was unaffected at 5 min. At the latter time, however, lipid peroxidation was already detectable in liver microsomal lipids. Treatment of rats with N,N′-diphenyl-p-phenylenediamine (DPPD) prior to CCl₄ poisoning did not prevent the peroxidation of microsomal lipids induced in vivo by carbon tetrachloride. Nor did it suppress the depression of G6P-ase. Malonic dialdehyde (MDA) production by liver homogenates or the microsome plus supernatant fraction was decreased by the addition of DPPD in vitro even at concentrations of 1.5 × 10^?5 and 1.5 × 10^?6 M. The in vitro pro-oxidant effect of CCl₄ was suppressed only when DPPD was present at the concentration of 1.5 × 10^?4 M. Pretreatment of rats with DPPD significantly decreased the liver steatosis induced by carbon tetrachloride but it was ineffective on the fall in the plasma triglycéride level caused by the halogenated hydrocarbon. The effect of DPPD on the liver steatosis was manifested both when DPPD was administered in oil and when it was given as an aqueous suspension. Only in the former instance was DPPD found in appreciable amounts in the microsomal lipids, while in the latter case it occurred only in traces in the microsomal fraction. It is suggested that the ability of DPPD to decrease CCl₄-induced liver triglyceride accumulation is not related to an action of DPPD on the membranes of the endoplasmic reticulum of the liver cell.     

大黄酸抑制四氯化碳诱导的大鼠肝纤维化形成

目的:观察大黄酸对实验性肝纤维化的影响.方法:采用60％的四氯化碳(CCl_4)及5％的乙醇制备肝纤维化动物模型,分别用小剂量、大剂量大黄酸(25 mg/kg,100 mg/kg体重)干预,测定血清丙氨酸氨基转移酶(ALT)、透明质酸(HA)、Ⅲ型前胶(PC-Ⅲ)及肝组织丙二醛(MDA)含量,免疫组化方法观察转化生长因子 β1(TGF-β1)、α平滑肌肌动蛋白(α-SMA)的表达情况,并观察肝组织胶原面积及病理变化.结果:大黄酸组较模型组:(1)血清ALT、HA、PC-Ⅲ水平及肝组织中MDA含量显著降低(P<0.01);(2)肝组织中TGF-β1,α-SMA的表达显著减少(P<0.05或P<0.01);③肝组织胶原面积明显减少,纤维化程度明显改善(P<0.05或P<0.01).结论:大黄酸具有保肝作用和抑制肝纤维化作用,其作用机制可能与其抗炎、抗氧化作用及抑制HSC活化、抑制TGF-β1作用有关.     

四氯化碳对大鼠肝毒性的时量关系研究

目的：探讨四氯化碳随用药时间和剂量的变化对大鼠肝脏功能与组织形态学的损害的时量关系，进一步了解四氯化碳对肝脏的毒理学作用。为研究护肝药提供动物实验模型，方法：大鼠皮下注射60％四氯化碳花生油，每周2次，分别在实验1、3、5、7、9wk观察大鼠血清丙氨酸氨基转移酶（ALT／GPT）、天冬氨酸氨基转氨酶（AST／GOT）、总蛋白（TP）和白蛋白（Alb)，血清透明质酸及肝组织病理变化和内脏器官重量指数的改变，以判断肝脏受损程度。结果：四氯化碳对大鼠肝脏的影响表现在1wk内可致大鼠血清ALT升高，3wk时发生肝组织脂变，5wk时肝组织轻度纤维增生，7wk时肝组织呈纤维化改变，9wk时肝组织发生明显的肝纤维化，甚至肝硬化。结果：大鼠皮下注射60％四氯化碳随染毒时间延长，染毒剂量的增加，对肝脏的毒性也不断加重。     

Restoration of hepatic mitochondria during recovery from carbon tetrachloride intoxication

During CCl₄ intoxication in rats, a disruption of hepatic mitochondrial structure and function occurs, which is characterized by a loss of respiratory activity, loss of phosphorylation coupled to respiration, and mitochondrial swelling, attended by loss of cristae structure. Within 15–25 hr, after full development of the mitochondrial lesion, the function and structure of the mitochondria are largely restored. Studies of the turnover of mitochondrial DNA and the rates of synthesis of mitochondrial DNA and protein indicated that the CCl₄-insulted hepatocyte is repairing the mitochondrial damage by the insertion of specific elements into the damaged organelle, rather than by proliferation of undamaged mitochondria for replacement. The failure of ethidium bromide, oxytetracycline and chloramphenicol, specific inhibitors of mitochondrial protein, and/or nucleic acid synthesis, to block this restoration substantiates the postulated repair process, and also indicates the non-critical nature of the respective mitochondrial functions during the repair process. Cytochrome measurements made during the period of acute damage revealed normal levels of cytochrome c, c₁ and aa₃. The observed elevation of cytochrome b is attributed to contamination of the preparation by hemoglobin.     

Effects of tamoxifen and levonorgestrel treatment on carbon tetrachloride induced alterations in rats.

Oestrogens cause progression in liver lesion, and thus ovariectomy improves hepatic injury both functionally and histologically. In the present study the efficacy of the antioestrogen tamoxifen (CAS 10540-29-1) was examined in chronical carbon tetrachloride damage. The results were compared with the effect of the progestogen levonorgestrel. Male Wistar rats were treated for 16 days. Blood sampling and autopsy were performed 2 h after last tamoxifen resp. levonorgestrel and 1 h after last CCl4 dosage. Tamoxifen diminished water content of the healthy liver. By fairly the same ratio it decreased high water content of the damaged liver. Levonorgestrel moderated water imbibition in CCl4 impairment. Tamoxifen caused protein synthesis in healthy and in injured liver. Levonorgestrel could not prevent protein loss associated with CCl4 damage. Tamoxifen counteracted, levonorgestrel moderated glycogen loss in liver lesion. Blood glucose was normal in all examined groups. Cytochrome P-450 decrease in CCl4 injury was moderated but not normalised by tamoxifen. Levonorgestrel was less effective. Cytochrome b5 content diminished in CCl4 lesion and both treatments restored it. Aminopyrine-N-demethylase was impaired by liver injury. An improvement was measured correlating with microsomal cytochrome P-450 content. This was significant with tamoxifen but not following levonorgestrel administration. The pathological serum bilirubin level of CCl4 lesion was normalised by tamoxifen as well as levonorgestrel treatment. The progestogen levonorgestrel moderated liver injury in reducing high water content, glycogen loss and normalising serum bilirubin. The antioestrogen tamoxifen seems to be a promising treatment in chronic hepatic impairment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Antigenical alterations of hepatocyte membrane in rats after long-term administration of ethanol and carbon tetrachloride

The presence of IgG over the hepatocyte's surfaces in ethanol- and/or carbon tetrachloride-pretreated rats was demonstrated as a very thin lineal fluorescent deposition around the membrane. The percentage of parenchymal IgG-positive liver cells ranged between 15 and 100% in all animals of treated groups. This suggests that ethanol may induce hepatic injury mediated by IgG autoantibodies which may be a response to an antigenical determinant present in hepatocytes altered by ethanol and/or carbon tetrachloride treatment.     

X-ray microanalysis of calcium, potassium, and phosphorus in liver mitochondria stressed by carbon tetrachloride

Previous measurements of elemental concentrations in liver mitochondria have generally required homogenization and fractionation of liver tissue, a procedure in which it is difficult to rule out ion movement between subcellular units. New techniques involving cryoultramicrotomy of rapidly frozen tissue, high resolution scanning transmission electron microscopy, and X-ray microanalysis were used to measure those elements in rat liver mitochondria reported to have changed following oral administration of carbon tetrachloride (CCl4). Increases in liver mitochondrial calcium were found 24 hr following intoxication by CCl4. Significant early (2 hr) mitochondrial increases in potassium and phosphorus were found following administration of CCl4. The electron microscope technique using quick-frozen samples promises to allow measurement of intracellular ionic concentrations under virtually lifelike conditions.     

Multiple treatment of propolis extract ameliorates carbon tetrachloride induced liver injury in rats

Propolis, a resinous wax-like beehive product has been used as a traditional remedy for various diseases due to a variety of biological activities of this folk medicine. In the present investigation, an attempt has been made to validate hepatoprotective activity of ethanolic extract of propolis (50-400mg/kg, p.o.) against carbon tetrachloride (CCl(4,) 0.5 ml/kg, p.o.) induced acute liver injury in rats. Silymarin, a known hepatoprotective drug was used as a positive control. Administration of CCl(4) altered various diagnostically important biochemical variables. Multiple treatment of propolis significantly prevented the release of transaminases, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transpeptidase, urea and uric acid in serum; improved the activity of hepatic microsomal drug metabolizing enzymes, i.e., aniline hydroxylase and amidopyrine-N-demethylase; significantly inhibited lipid peroxidation and markedly enhanced glutathione in liver and kidney as well as brought altered carbohydrate contents (blood sugar and tissue glycogen), protein contents (serum, microsomal and tissue protein) and lipid contents (serum and tissue triglycerides, serum cholesterol, total and esterified cholesterol in tissue) towards control. Propolis treatment also reversed CCl(4) induced severe alterations in histoarchitecture of liver and kidney in a dose dependent manner. Hepatoprotective activity of propolis at doses of 200 and 400 mg/kg was statistically compared to silymarin and found that propolis exhibited better effectiveness than silymarin in certain parameters, concluded its hepatoprotective potential.     

Ethanol feeding stimulates trichloromethyl radical formation from carbon tetrachloride in liver

1. Female, Sprague-Dawley rats were fed liquid ethanol or control diets, both of which contained fat either at 35% (high fat, HF) or 12% (low fat, LF) of total calories. The rats were given an oral dose of 13CCl4 along with the spin trapping agent, phenyl tert.-butyl-nitrone (PBN). 2. Analysis of the hepatic lipid extracts revealed a signal due to the trichloromethyl radical (CCl3) adduct of PBN. Ethanol feeding in the HF diet increased the signal intensity two-fold over controls, whereas ethanol feeding in the LF diet caused only a 35% increase. 3. In isolated microsomes, ethanol feeding in HF or LF diets increased CCl3 formation by approx. 8-fold and 4-fold, respectively, over control values. These data support the hypothesis that ethanol induces a cytochrome P-450 isozyme that is highly active in the metabolism of CCl4 to the CCl3 radical. 4. Ethanol feeding markedly enhanced the hepatotoxicity of CCl4; however, there were no differences in the loss of hepatic enzymes into blood between the ethanol plus HF or ethanol plus LF groups. Thus, ethanol is likely to increase CCl4 toxicity by some mechanism in addition to increased trichloromethyl radical formation.     

Hepatoprotective effects of total saponins isolated from Taraphochlamys affinis against carbon tetrachloride induced liver injury in rats

In this study, rats were orally treated with the total saponins of Taraphochlamys affinis (TSTA) daily with administration of CCl4 twice a week for 8 weeks. Compared to the normal control, CCl4 induced liver damage significantly increased the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in serum and decreased the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px), and glutathione reductase (GSH-Rd) in liver. Meanwhile content of hepatic malondialdehyde (MDA), which was oxidative stress marker, was increased. Histological finding also confirmed the hepatotoxic characterization in rats. Furthermore, proinflammatory mediators including tumor necrosis factor-α(TNF-α) in serum, prostaglandin E2 (PGE2), inducible enitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in liver were detected with elevated contents, while expression of xenobiotic metabolizing enzyme--cytochrome P4502E1 (CYP2E1) was inhibited. The results revealed that TSTA not only significantly reversed CCl4 originated changes in serum toxicity and hepatotoxic characterization, but also altered expression of hepatic oxidative stress markers and proinflammatory mediators, combined with restoring liver CYP2E1 level. The results indicated that protective effect of TSTA against CCl4-induced hepatic injury may rely on its effect on reducing oxidative stress, suppressing inflammatory responses and improving drug-metabolizing enzyme activity in liver.