Effect of aging on liver glutathione levels and hepatocellular injury from carbon tetrachloride, allyl alcohol or galactosamine

Severity of liver damage 24 hr after i.p. administration of carbon tetrachloride (0.2 ml/kg), allyl alcohol (0.036 ml/kg) or galactosamine (400 mg/kg) was evaluated in male rats at 4-5, 14-15 or 24-25 months of age. Allyl alcohol hepatotoxicity, as judged by light microscopy and serum alanine aminotransferase levels, increased markedly as a function of age. In contrast, carbon tetrachloride and galactosamine toxicities were unchanged or slightly diminished in old rats. Hepatic glutathione (GSH) concentrations were unaffected by aging; thus, the age-dependent increase in susceptibility to allyl alcohol toxicity was not a result of diminished GSH availability in old age. Hepatotoxicant-induced changes in GSH were observed in allyl alcohol-treated old rats (20% increase) and in galactosamine-treated young-adult and middle-aged rats (30% decrease).     

Allyl alcohol partially protects murine hepatic mitochondria against carbon tetrachloride

Male CD-1 mice were treated with carbon tetrachloride (CCl4, 1 ml/kg, i.p.), or allyl alcohol (AA, 0.05 ml/kg, i.p.) or both 24 h prior to sacrifice. The livers were removed, homogenized and mitochondrial preparations were fractionated. Electron micrographs of the mitochondrial pellet from the livers of mice treated with CCl4 showed lysed and fragmented mitochondria as well as a few condensed mitochondria. No normal intact mitochondria were observed. The mitochondrial pellet from AA-treated livers was characterized by a preponderance of condensed mitochondria whether CCl4 was given also or not. The mitochondrial fraction from CCl4-treated mice failed to utilize oxygen whereas that fraction from mice given AA did not differ from control in either its basal oxygen consumption (state 4) or oxygen utilization after the addition of adenosine diphosphate (state 3). State 4 respiration differed slightly but significantly from control in mitochondria from mice given both AA and CCl4 whereas state 3 respiration was greatly and significantly decreased from that of control values. Electron micrographs of liver slices from mice given AA or the combination of AA and CCl4 showed normal mitochondrial morphology. Thus, AA appears to exert an influence, perhaps at the level of the mitochondrial membrane, which is manifested only after their isolation. This effect which results in the condensation of isolated mitochondria serves to partially protect them against CCl4, but it did not prevent the characteristic CCl4-induced centrilobular necrosis.     

Carcinogenesis Bioassay of Allyl Isothiocyanate

Carcinogenesis Bioassay of Allyl Isothiocyanate. Dunnick, JuneK., Prejean, J. David, Haseman, Joseph; Thompson, Roger B.,Giles, Herschell D. and McConnell, Ernest E. (1982). Fundam.Appl. Toxicol. 2:114-120. Allyl isothiocyanate is a food additivepresent in many foods and a constituent of oil of mustard andmustard, and is generally considered safe for human consumption.This study was undertaken to determine the carcinogenic potentialof food grade allyl isothiocyanate. Allyl isothiocyanate wasadministered at 12 or 25 mg/kg in corn oil five times per weekby gavage to groups of 50 Fischer 344 rats and 50 B6C3F₁ miceof each sex for 103 weeks. Groups of 50 rats and 50 mice ofeach sex received corn oil alone and served as vehicle controls.Transitional-cell papillomas in the urinary bladder occurredin dosed male rats with a statistically significant trend (p< 0.05; controls, 0/49, 0%, low-dose, 2/49, 4%; high-dose,4/49, 8%). This tumor has not been observed among 568 untreatedmale control F344 rats at this laboratory. The prevalence oftransitional-cell papillomas in male vehicle control and untreatedcontrol rats in all laboratories in the NCI/NTP Bioassay Program²is only 1/994 (0.1%) and 5/3888 (0.1%) respectively. Administrationof allyl isothiocyanate also increased the prevalence of epithelialhyperplasia of the urinary bladder in male rats. Leukemia occurredin dosed male rats with a statistically significant positivetrend (p < 0.05; controls, 2/50,4%; low-dose, 6/50, 12%;high-dose, 8/50, 16%). However, because the incidence of leukemiain dosed male rats is similar to the mean historical controlrate at this laboratory, this increase was not considered tobe related to the administration of allyl isothiocyanate. Fibrosarcomasin the subcutaneous tissue occurred in female rats with a statisticallysignificant positive trend (p < 0.05; controls, 0/50, 0%;low-dose, 0/50, 0%; high-dose, 3/50, 6%), but the prevalencein the high-dose group was not significant when compared withthat in the control group. Thus, the evidence for allyl isothiocyanatecausing this tumor was considered equivocal. Evidence of anassociation between administration of allyl isothiocyanate andincreased tumor incidence was not seen in mice. However, anincreased prevalence of cytoplasmic vacuolization in the liverof dosed male mice was related to administration of allyl isothiocyanate(controls, 2/49,4%; low-dose, 8/49, 16%; high-dose, 13/50, 26%).In large doses, food grade allyl isothiocyanate produces a slightbut statistically significant increase in benign urinary bladdertumors (a rare neoplasm) in male F344 rats.     

NTP toxicology and carcinogensis Studies of 2,4-hexadienal (89% trans,trans isomer, CAS No. 142-83-6; 11% cis,trans isomer) (Gavage Studies)

2,4-Hexadienal, a colorless to yellow liquid with a pungent "green" or citrus odor, is used as a food additive for flavor enhancement, as a fragrance agent, as a starting material or intermediate in synthetic reactions in the chemical and pharmaceutical industries, as a fumigant, and as a corrosion inhibitor for steel. 2,4-Hexadienal was nominated for study by the National Cancer Institute because of the potential for carcinogenicity based on its alpha,beta-unsaturated aldehyde structure and the potential link between exposure to lipid peroxidation products in the diet and human malignancies. The commercial product is a mixture containing chiefly trans,trans-2,4-hexadienal in equilibrium with cis,trans-2,4-hexadienal. Male and female F344/N rats and B6C3F1 mice received 2,4-hexadienal (89% trans,trans; 11% cis,trans) in corn oil by gavage for 16 days, 14 weeks, or 2 years. Tissues and plasma from dosed rats were examined for malondialdehyde and glutathione concentrations, and DNA adducts were characterized in liver and forestomach samples from dosed rats and mice. Genetic toxicology studies were conducted in Salmonella typhimurium, rat and mouse bone marrow cells, and mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 3, 9, 27, 80, or 240 mg 2,4-hexadienal/kg body weight in corn oil by gavage, 5 days per week, for 16 days. Three male and three female 240 mg/kg rats died before the end of the study. Mean body weight gains of 240 mg/kg rats were significantly less than those of the vehicle controls. Clinical findings included diarrhea, ataxia, lethargy, and nasal/eye discharge in males, and lethargy, paleness, and abnormal breathing in females in the 240 mg/kg groups. Liver weights of 240 mg/kg females were significantly greater than those of the vehicle controls. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were present in most 240 mg/kg rats, and forestomach epithelial hyperplasia was microscopically evident in most 80 mg/kg rats. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 3, 9, 27, 80, or 240 mg/kg, 5 days per week, for 16 days. Chemical-related deaths occurred in one male and one female in the 240 mg/kg groups. Female mice in the 240 mg/kg group lost weight during the study. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were present in all 240 mg/kg mice, and forestomach epithelial hyperplasia and hyperkeratosis were microscopically evident in 80 mg/kg mice. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 7.5, 15, 30, 60, or 120 mg/kg, 5 days per week, for 14 weeks. All rats survived to the end of the study. Mean body weights of 30, 60, and 120 mg/kg males were significantly less than those of the vehicle controls. The only clinical finding attributed to 2,4-hexadienal administration was hypersalivation in 30 and 120 mg/kg males and females. The incidences of forestomach hyperplasia and nasal olfactory atrophy or necrosis were significantly increased in 120 mg/kg rats. Nasal lesions occurred in most 120 mg/kg male rats. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 7.5, 15, 30, 60, or 120 mg/kg, 5 days per week, for 14 weeks. No deaths were attributed to administration of 2,4-hexadienal. Mean body weights of males and females were similar to those of the vehicle controls throughout the study. Clinical findings included salivation and anal wetness in males and females. Kidney weights of 60 and 120 mg/kg males and liver weights of 60 mg/kg males and females were significantly greater than those of the vehicle controls. The incidences of forestomach hyperplasia and/or nasal olfactory atrophy or necrosis were significantly increased in 120 mg/kg mice. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were administered 2,4-hexministered 2,4-hexadienal in corn oil by gavage at doses of 0, 22.5, 45, or 90 mg/kg, 5 days per week, for up to 105 weeks. Survival of all dosed groups of rats was similar to that of the vehicle control groups. The mean body weights of 90 mg/kg males were generally less than those of the vehicle controls throughout the study. The incidences of squamous cell papilloma of the forestomach occurred with positive trends in male and female rats. This neoplasm was found in 58% of males and 34% of females in the 90 mg/kg groups. In the forestomach of male rats, papilloma multiplicity was increased in the 90 mg/kg group, and squamous cell carcinomas were found in one 45 mg/kg male and two 90 mg/kg males. Epithelial hyperplasia of the forestomach occurred in most 45 and 90 mg/kg rats. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 30, 60, or 120 mg/kg, 5 days per week, for up to 105 weeks. Survival of dosed mice was similar to that of the vehicle controls. The mean body weights of all dosed groups were generally similar to those of the vehicle controls throughout the study. The incidences of squamous cell papilloma of the forestomach occurred with positive trends in male and female mice; squamous cell carcinomas were present in 120 mg/kg males and females. Epithelial hyperplasia of the forestomach occurred in many 120 mg/kg mice. Two 120 mg/kg males had uncommon squamous cell carcinoma of the oral cavity (tongue). GENETIC TOXICOLOGY: 2,4-Hexadienal was mutagenic in S. typhimurium strain TA100 with and without induced hamster or rat liver enzymes; no mutagenic activity was detected with strains TA1535 or TA98, with or without S9. Results of bone marrow tests in male rats and male mice given intraperitoneal injections of 2,4-hexadienal showed a small increase in the induction of micronucleated erythrocytes. However, neither test was repeated, and the test results were judged to be inconclusive. Results of peripheral blood micronucleus tests in male and female mice treated with 2,4-hexadienal by gavage for 14 weeks were negative. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity* of 2,4-hexadienal in male and female F344/N rats and male and female B6C3F1 mice based on increased incidences of squamous cell neoplasms of the forestomach. The occurrence of squamous cell carcinoma of the oral cavity (tongue) in male B6C3F1 mice may have been related to the administration of 2,4-hexadienal. Hyperplasia of the forestomach in male and female rats and mice was associated with administration of 2,4-hexadienal. Synonyms: Hexa-2,4-dienal; 2,4-hexadienal; 2,4-hexadien-1-al; 2,4-Hx; 1,3-pentadiene-1-carboxaldehyde; 2-propylene acrolein; sorbaldehyde; sorbic aldehyde     

Liver damage does not increase the sensitivity of mice to cyanide given acutely

The major detoxification pathway for cyanide (CN) in many species is a biotransformation to the less toxic thiocyanate (SCN). Hepatic thiosulfate: cyanide sulfurtransferase (rhodanese) is the principal enzyme demonstrating in vitro catalytic activity. Despite the assumed importance of the hepatic enzyme for CN detoxification in vivo, the effects of liver damage (surgical or chemical) on cyanide lethality in animals have not been examined previously. Male CD-1 mice were pretreated with carbon tetrachloride (CCl4, 1 ml/kg, i.p.) 24 h prior to the administration of sodium cyanide (NaCN). In other experiments CCl4 was given in the same doses at both 48 h and 24 h prior to NaCN. Hepatotoxicity was documented by elevated serum glutamicpyruvic transaminase (SGPT) activity, by histologic evaluation of the extent of cellular necrosis, by electron microscopy of the mitochondrial fraction, and by the increased duration of zoxazolamine-induced paralysis. Lethality was not changed by CCl4 pretreatments when NaCN was given alone in doses of 4 or 6 mg/kg or at a dose of 10.7 mg/kg following sodium thiosulfate (Na2S203, 1 g/kg, i.p.). A small but statistically significant protective effect was exhibited by CCl4 when NaCN was given at a dose of 16 mg/kg following the administration of Na2S203. Rhodanese activity as measured in mitochondrial preparations fractionated from the livers of mice pretreated with CCl4 was not different from that in animals given the corn oil vehicle even though electron micrographs showed extensive mitochondrial damage. No difference in CN lethality was evident between sham-operated mice and partially (2/3) hepatectomized mice at 24 h post-surgery. An intact healthy liver does not appear to be essential for cyanide detoxification in mice whether or not thiosulfate is also given. Because rhodanese activity was slightly but significantly higher in mitochondria lysed by Triton X-100 than in intact mitochondria, the mitochondrial membrane may constitute a barrier to Na2S203.     

Involvement of nonparenchymal cells in oxygen-dependent hepatic injury by allyl alcohol.

Allyl alcohol injury to hepatocytes in the perfused liver is oxygen-dependent. It is not known if this injury involves direct action of allyl alcohol on hepatocytes or requires participation of other cell types (e.g., Kupffer cells) present in the liver. Accordingly, the action of allyl alcohol (100-500 microM) on isolated hepatocytes was studied using cells maintained at either 95 or 21% O2. Allyl alcohol toxicity, as indexed by trypan blue uptake, lactate dehydrogenase release, and ATP content, did not differ in the two groups of cells, suggesting that O2 dependency of allyl alcohol toxicity involves other cell types. Administration of allyl alcohol (30 or 40 mg/kg, ip) to rats caused extensive hepatic necrosis localized primarily to periportal regions. To test the involvement of Kupffer cells in the genesis of this injury, male rats (200-350 g) were treated with gadolinium chloride (GdCl3, 10 mg/kg, iv) which diminishes Kupffer cell function and number. The extent of hepatic damage assessed by light microscopy and serum enzymes, aspartate aminotransferase and alanine aminotransferase, was markedly attenuated by pretreatment of rats with GdCl3 24 hr prior to allyl alcohol injection. Thus, O2-dependent hepatic necrosis caused by allyl alcohol involves the presence of Kupffer cells. Since GdCl3 did not prevent toxicity in the perfused liver, circulating blood elements may also contribute to injury of the liver by allyl alcohol in vivo.     

A comparative 90-day toxicity study of allyl acetate, allyl alcohol and acrolein

Allyl acetate (AAC), allyl alcohol (AAL), and acrolein (ACR) are used in the manufacture of detergents, plastics, pharmaceuticals, and chemicals and as agricultural agents. A metabolic relationship exists between these chemicals in which allyl acetate is metabolized to allyl alcohol and subsequently to the highly reactive, alpha,beta-unsaturated aldehyde, acrolein. Due to the weaker reactivity of the protoxicants, allyl acetate and allyl alcohol, relative to acrolien we hypothesized the protoxicants would attain greater systemic exposure and therefore deliver higher doses of acrolein to the internal organs. By extension, the higher systemic exposure to acrolein we hypothesized should lead to more internal organ toxicity in the allyl acetate and allyl alcohol treated animals relative to those treated with acrolein. To address our hypothesis we compared the range of toxicities produced by all three chemicals in male and female Fischer 344/N rats and B6C3F1 mice exposed 5 days a week for 3 months by gavage in 0.5% methylcellulose. Rats (10/group) were dosed with 0-100mg/kg allyl acetate, 0-25mg/kg allyl alcohol, or 0-10mg/kg acrolein. Mice (10/group) were dosed with 0-125mg/kg allyl acetate, 0-50mg/kg allyl alcohol, or 0-20mg/kg acrolein. The highest dose of allyl acetate and acrolein decreased survival in both mice and rats. The primary target organ for the toxicity of all three chemicals in both species and sexes was the forestomach; squamous epithelial hyperplasia was observed following exposure to each chemical. In both species the highest allyl acetate dose group exhibited forestomach epithelium necrosis and hemorrhage and the highest dose of acrolein led to glandular stomach hemorrhage. Liver histopathology was the most apparent with allyl acetate, was also observed with allyl alcohol, but was not observed with acrolein. All chemicals had effects on the hematopoietic system with allyl acetate having the most pronounced effect. When dosed at quantities limited by toxicity, allyl acetate and allyl alcohol produce higher levels of urinary mercapturic acids than the minimally toxic dose of acrolein. This observation is likely due to biotransformation of allyl acetate and ally alcohol to acrolein that occurs after absorption and suggests that these chemicals are protoxicants that increase systemic exposure of acrolein. Increased systemic exposure to acrolein is likely responsible for the differences in hepatic toxicological profile observed with these chemicals.     

Hepatotoxic interactions of ethanol with allyl alcohol or carbon tetrachloride in rats.

To assess whether potential toxic interactions occur between ethanol and allyl alcohol or carbon tetrachloride following subacute, concurrent chemical exposure, male Fischer 344 rats, approximately 70 d of age, were given ethanol at 0, 0.05, 0.1, 0.2, or 0.5 ml/kg in corn oil daily by gavage for 14 d (ETOH group), or the same levels of ethanol with 21 mg allyl alcohol/kg (ALAC group), or the same levels of ethanol with 20 mg carbon tetrachloride/kg (CCL4 group). Hepatic response was assessed 24 h after the last dose. Interactions were evaluated by comparing the ETOH group with either the ALAC group or the CCL4 group using multivariate analysis of variance procedures. No statistically significant interaction was seen between the ETOH group and the ALAC group at the dosages used. Although an interaction between ethanol and carbon tetrachloride given simultaneously was not statistically significant, a small interactive effect on weight gain from d 0 to termination was apparent (p = .057). Exposure to ethanol alone resulted in a concentration-dependent decrease in absolute and relative liver weight, with a threshold between 0.05 and 0.1 ml/kg. There was no histopathological evidence of hepatic damage with ethanol alone, and no effect on hepatic cytochrome P-450 and glutathione levels or on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALK). Exposure to allyl alcohol alone resulted in significant increases in absolute and relative liver weights, liver glutathione, and periportal hepatocellular vacuolar degeneration. Exposure to carbon tetrachloride alone resulted in significant increases in absolute and relative liver weight, serum levels of ALT, AST, and ALK, and centrilobular hepatocellular vacuolar degeneration and necrosis. These observations indicate that subacute, concurrent exposure of ethanol with carbon tetrachloride or allyl alcohol at ethanol levels comparable to those reported in gavage vehicles did not result in interactive toxicity.     

Vehicle-dependent oral absorption and target tissue dosimetry of chloroform in male rats and female mice

Chloroform-induced toxicity in rodents depends on oral dose regimen. We evaluated the absorption and tissue dosimetry of chloroform after gavage administration in various vehicles to male Fischer 344 rats and female B6C3F₁ mice. Animals received a single dose of chloroform in corn oil, water, or aqueous 2% emulphor at doses (15–180 and 70–477 mg/kg for rats and mice) and dose volumes (2 and 10 ml/kg for rats and mice) used in previously reported toxicity studies. Blood, liver, and kidney chloroform concentration-time courses were determined. Gavage vehicle had minimal effects on chloroform dosimetry in rats. In mice, however, tissue chloroform concentrations were consistently greater for aqueous versus corn oil vehicle. At the low dose volume used for rats (2 ml/kg) gavage vehicle may not play a significant role in chloroform absorption and tissue dosimetry; at the higher dose volume used for mice (10 ml/kg), vehicle may be a critical factor.     

Renal toxicity of perchloroethylene and S-(1,2,2-trichlorovinyl)glutathione in rats and mice: sex- and species-dependent differences

Suspensions of renal cells from rats and renal mitochondria from rats and mice were used to assess the sex and species dependence of acute toxicity due to perchloroethylene (Perc) and its glutathione conjugate S-(1,2,2-trichlorovinyl)glutathione (TCVG). A marked sex dependence in the acute cytotoxicity of both Perc and TCVG was observed: Perc caused significant release of lactate dehydrogenase (LDH) in isolated kidney cells from male but not female rats, and TCVG caused much more LDH release from male than female rat kidney cells. Assessment of toxicity in suspensions of isolated mitochondria from kidneys of male and female rats revealed a generally similar pattern of sensitivity, with mitochondria from males exhibiting significantly more inhibition of State 3 respiration and decrease of respiratory control ratio than mitochondria from females. Respiratory function in mitochondria from male and female mice, however, was also significantly inhibited by Perc or TCVG but exhibited little sex dependence in the degree of inhibition. Comparison with results from similar studies using the congener trichloroethylene and its glutathione conjugate suggested that Perc and TCVG are more potent nephrotoxicants. Neither Perc nor TCVG produced any significant effects on cytotoxicity or mitochondrial function in isolated hepatocytes from rats or in isolated liver mitochondria from rats or mice, suggesting that the liver is not a major acute target for Perc or its glutathione conjugate. Thus, many of the species-, sex-, and tissue-dependent differences in toxicity of Perc and TCVG that are observed in vivo are also observed in these in vitro models.     

Differing hepatotoxicity and lethality after subacute trichloroethylene exposure in aqueous or corn oil gavage vehicles in B6C3F1 mice

Subacute toxicity of trichloroethylene (TCE) was evaluated in male and female B6C3F1 mice using corn oil or aqueous gavage vehicles. Mice received oral doses of TCE five times a week for 4 weeks at 600, 1200 and 2400 mg/kg/day for males and 450, 900 and 1800 mg/kg/day for females. Vehicle control mice were dosed with either corn oil or a 20% aqueous solution of Emulphor. A dose-related increase in lethality occurred in male and female mice receiving TCE in Emulphor but not corn oil during the first week of treatment. Lethality was consistent with central nervous system depressant effects of TCE. After 4 weeks of exposure, body weights were not altered by TCE but liver/body weight ratios were uniformly increased by TCE administered in either vehicle in both sexes. Only male mice treated with TCE in corn oil, however, sustained elevations in serum enzyme levels, accompanied by liver histopathology. TCE in corn oil produced inflammation-associated focal necrosis in 30-40% of the male mice, with increasing severity from low to high dose. Lipid accumulation, as indicated by Oil-Red O staining, was most prevalent in male mice treated with TCE in corn oil but also occurred to a lesser degree in animals receiving either gavage vehicle alone. This study indicates that the type of oral gavage vehicle is an important factor in determining the nature of TCE toxicity.     

Effect of leptin administration on plasma and tissue lipids in alcohol induced liver injury

Previous studies suggest a possible link between leptin and hepatic inflammation; however the role of leptin in liver diseases remains unclear. The purpose of the present study was to evaluate the effect of leptin on plasma and tissue lipids in experimental hepatotoxicity. Administering ethanol (6.32 g/kg body weight) to 4-week-old healthy mice for 45 days resulted in significantly elevated levels of plasma and tissue phospholipids, triglycerides and free fatty acids as compared with those of the control animals. Subsequent to the experimental induction of hepatotoxicity (i.e., the initial period of 30 days) exogenous leptin was simultaneously administered (230 microg/kg body weight) every alternate day for 15 days along with the daily dose of alcohol. Leptin administration to control and alcohol-treated mice reduced the weight gain and significantly lowered the levels of plasma and tissue lipids as compared with the untreated control and alcohol supplemented mice. It is postulated that the increase in systemic leptin levels lower the plasma and tissue lipids of alcohol-treated mice, which operates independently of changes in food intake, body weight and the size of the fat stores.     

Pentoxifylline attenuates bacterial lipopolysaccharide-induced enhancement of allyl alcohol hepatotoxicity.

Small amounts of exogenous lipopolysaccharide (LPS) (10 ng/kg-100 microg/kg) enhance the hepatotoxicity of allyl alcohol in male Sprague-Dawley rats. This augmentation of allyl alcohol hepatotoxicity appears to be linked to Kupffer cell function, but the mechanism of Kupffer cell involvement is unknown. Since Kupffer cells produce tumor necrosis factor-alpha (TNF alpha) upon exposure to LPS, and this cytokine has been implicated in liver injury from large doses of LPS, we tested the hypothesis that TNF alpha contributes to LPS enhancement of allyl alcohol hepatotoxicity. Rats were treated with LPS (10-100 microg/kg iv) 2 h before allyl alcohol (30 mg/kg ip). Co-treatment with LPS and allyl alcohol caused liver injury as assessed by an increase in activity of alanine aminotransferase in plasma. Treatment with LPS caused an increase in plasma TNF alpha concentration, which was prevented by administration of either pentoxifylline (PTX) (100 mg/kg iv) or anti-TNF alpha serum (1 ml/rat iv) one h prior to LPS. Only PTX protected rats from LPS-induced enhancement of allyl alcohol hepatotoxicity; anti-TNF alpha serum had no effect. Exposure of cultured hepatocytes to LPS (1-10 microg/ml) or to TNF alpha (15-150 ng/ml) for 2 h did not increase the cytotoxicity of allyl alcohol (0.01-200 microM). These data suggest that neither LPS nor TNF alpha alone was sufficient to increase the sensitivity of isolated hepatocytes to allyl alcohol. Furthermore, hepatocytes isolated from rats treated 2 h earlier with LPS (i.e., hepatocytes which were exposed in vivo to TNF alpha and other inflammatory mediators) were no more sensitive to allyl alcohol-induced cytotoxicity than hepatocytes from na?ve rats. These data suggest that circulating TNF alpha is not involved in the mechanism by which LPS enhances hepatotoxicity of allyl alcohol and that the protective effect of PTX may be due to another of its biological effects.     

锌和维生素A对乙醇致大鼠睾丸损伤的保护作用

目的研究锌和维生素A（VA）对长期摄入乙醇致大鼠睾丸损害的保护作用及可能机制。方法 40只健康雄性成年SD大鼠随机分为对照组、乙醇组、乙醇＋葡萄糖酸锌组、乙醇＋VA组,每组10只,4组每日分别灌胃给予乙醇0、7.5g/kg、乙醇7.5g/kg＋葡萄糖酸锌7.7mg/kg、乙醇7.5g/kg＋VA50μg/kg,连续13周。对4组大鼠的精子计数、精子活动率、精子畸形率、血清睾酮（T）、黄体生成素（LH）、卵泡刺激素（FSH）含量进行检测,光、电镜观察睾丸的形态改变。同时测定睾丸线粒体中丙二醛（MDA）的产生量,免疫组织化学法检测睾丸组织中iNOS的表达。结果与对照组相比,乙醇组大鼠精子计数减少,精子活动率下降,精子畸形率升高（P〈0.05）,血清T、LH、FSH水平明显降低（P〈0.05）;睾丸生精上皮结构破坏,支持细胞和各级生精细胞均有退化变性;睾丸生精细胞iNOS表达明显增强（P〈0.05）;睾丸线粒体丙二醛含量明显升高（P〈0.05）。与乙醇组相比,乙醇＋葡萄糖酸锌组和乙醇＋VA组精子计数、精子活动率有所上升,生精细胞退化变性程度减轻,睾丸生精细胞iNOS表达减弱（P〈0.05）,睾丸线粒体MDA减少,但血清T、LH、FSH水平仍低于对照组（P〈0.05）。结论补充锌和VA可以限制乙醇引起的睾丸过氧化损伤,保护睾丸的生精功能,但仍有生殖内分泌激素合成障碍。     

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。     

Effect of endrin and endrin derivatives on hepatobiliary function and carbon tetrachloride-induced hepatotoxicity in male and female rats

The effects of the cyclodiene pesticide, endrin, and its aldehyde and ketone metabolites on hepatobiliary function and CCl4-induced hepatotoxicity were investigated in Sprague-Dawley rats. The rats were given control diet or diets containing 5 or 10 ppm endrin, 10 ppm endrin aldehyde or 5 ppm endrin ketone for 15 days. Three to six rats from each treatment group were given a single ip dose (100 microliter/kg body weight) of CCl4 in corn oil (1 ml/kg) on day 15. Levels of serum glutamic-oxalacetic transaminase (SGOT), glutamic-pyruvic transaminase (SGPT), isocitrate dehydrogenase and ornithine-carbamyl transferase, bile flow and biliary excretion of an anionic model compound, phenolphthalein glucuronide (PG), were measured on day 16. Dietary treatment with endrin at either dose level did not significantly elevate serum enzyme levels, while endrin aldehyde produced a slight increase in SGOT and SGPT and endrin ketone produced a small elevation in SGPT levels. Treatment with endrin aldehyde or endrin ketone did not result in significant alterations of bile flow or biliary PG excretion. Treatment with 5 ppm endrin produced a significant reduction in bile flow and a corresponding reduction in PG excretion by male rats, whereas treatment with 10 ppm endrin reduced only the PG excretion by male rats. Female rats treated with 5 or 10 ppm endrin showed a dose-dependent choleretic effect with a commensurate increase in PG excretion. With the exception of a further slight reduction in PG excretion by male rats, treatment with the endrin or endrin derivative did not potentiate CCl4-induced alterations in hepatobiliary functions. Although the levels of some serum enzymes of rats given endrin or endrin derivatives plus CCl4 were elevated over those of rats given CCl4 alone, the increases were not of the magnitude of those that have been reported previously for chlordecone. Generally, female rats challenged with CCl4 or endrin/CCl4 exhibited greater increases in serum enzyme levels than did male rats given corresponding treatments.     

The oxidation of acrolein by rat liver aldehyde dehydrogenases. Relation to allyl alcohol hepatotoxicity

The oxidation of acrolein by aldehyde dehydrogenase was studied in several subcellular fractions of rat liver by measuring acrolein-dependent production of NADH from NAD+. Mitochondrial and cytosolic fractions each contained two aldehyde dehydrogenase activities with Km values for acrolein of 0.4-0.7 mM and 0.015-0.025 mM. Microsomes demonstrated only a high Km (1.5 mM) activity. The low Km activities of mitochondria and cytosol differed in their sensitivity to inhibition by chloral hydrate and in their response to 1 mM MgCl2 (activation vs. inhibition). The metabolism of acrolein by low Km aldehyde dehydrogenase activities was markedly depressed in mitochondrial or cytosolic fractions from rats pretreated with cyanamide (2 mg/kg for 1 hr) or disulfiram (100 mg/kg for 24 hr). The effect of aldehyde dehydrogenase inhibition on allyl alcohol toxicity was determined by pretreating rats with cyanamide or disulfiram prior to treatment with allyl alcohol. Hepatotoxicity was assessed on the basis of elevated serum alanine aminotransferase and sorbitol dehydrogenase activities and the loss of microsomal cytochrome P-450. Pretreatment with the aldehyde dehydrogenase inhibitors enhanced the hepatotoxicity of allyl alcohol in both male and female rats. The results suggest that acrolein metabolism by rat liver aldehyde dehydrogenase isozymes is important for the inactivation of allyl alcohol-derived acrolein.     

Acute Hepatotoxic and Nephrotoxic Effects of Chloroform in Male F-344 Rats and Female B6C3F1 Mice

Previous studies demonstrated that chloroform given by oralgavage in corn oil caused an increased incidence of liver tumorsin male and female mice and kidney tumors in male rats, whileadministration in drinking water resulted in an increased tumorincidence only in the kidneys of the male rats. The tumorigenicityof this nongenotoxic agent has been postulated to be linkedwith cytolethality and cell proliferation. This study examinedthe organ-specific toxicity of acute doses of chloroform. MaleF-344 rats were given chloroform by gavage in corn oil at thebioassay doses of chloroform of 0 and 180 mg/kg body wt as wellas 34 and 477 mg/kg and necropsied 24 hr later. Additional ratswere given a single dose of 180 mg chloroform/kg and administeredbromodeoxyuridine (BRDU) 2 hr prior to necropsy at 0.5, 1, 2,4, and 8 days after chloroform treatment. Female B6C3F1 micewere given chloroform by gavage at the bioassay doses of 0,238, and 477 mg/kg as well as 34 mg/kg and necropsied at 24hr after treatment. Additional mice were given a single doseof 350 mg chloroform/kg, labeled with BRDU, and necropsied at0.5, 1, 2, 4, and 8 days after treatment. The kidneys of malerats administered 34, 180, and 477 mg chloroform/kg exhibitedmild to severe proximal tubular necrosis in a dose-dependentmanner. A 20-fold increase in the labeling index (LI, the percentageof nuclei in S-phase) in the proximal tubule cells was observed2 days after treatment with the bioassay dose of 180 mg/kg.The livers of male rats exhibited only slight to moderate multifocalcentrilobular necrosis at 180 and 477 mg/kg. A 10-fold increasein the LI was observed in the liver of male rats given 477 mg/kg,but no increase was observed at the bioassay dose of 180 mg/kg.In contrast to male rats, female mice developed a dose-dependentcentrilobular hepatic necrosis at 238 and 477 mg/kg. No renallesions were observed in female mice at any dose. A peak increasein LI of 38-fold was observed in hepa-tocytes in the liversof female mice 2 days after treatment with 350 mg chloroform/kg,with only a 2-fold increase in LI observed in the kidneys. Thesedata indicate that acute chloroform-induced cytolethality leadsto increased cell proliferation and that the organ-specificpattern of toxicity is the same as the organ-specific patternof tumor formation. These observations are suggestive of a rolefor induced cell proliferation in tumor formation and indicatethat more extensive cell proliferation Studies are Warranted.     

Effects of the environment on the behavioural response of mice to non-ataxic doses of ethyl alcohol.

An ethological analysis was used to examine the effects of ethyl alcohol on social behaviour in mice which were placed in different social contexts. In encounters between unfamiliar males, alcohol-treated mice from a diverse environment showed more exploration on the bars of an unfamiliar cage and less social investigation than controls. In an encounter situation between males and females, male mice given alcohol showed a significant increase in frequency and duration of all forms of social and sexual investigation other than mounts and attempted mounts compared with untreated males. In a territorial situation, alcohol administration before territory establishment resulted, on each of four occasions, in the dominant mouse of the alcohol-treated group becoming despot over the whole enclosure, whereas after territory establishment this effect was not seen. The overall effect of alcohol was, therefore, to increase the type of behaviour that was already stimulated by the test situation. The significance of these findings in relation to the differential effects of alcohol on different areas of the nervous system is discussed.     

Methoxyflurane enhances allyl alcohol hepatotoxicity in rats. Possible involvement of increased acrolein formation

The effect of methoxyflurane anesthesia on allyl alcohol-induced hepatotoxicity and the metabolism of allyl alcohol was studied in male rats. Hepatotoxicity was assessed by the measurement of serum alanine aminotransferase activity and histopathological examination. Allyl alcohol-induced hepatotoxicity was enhanced when allyl alcohol (32 mg/kg) was administered 4 hr before or up to 8 days after a single 10-min exposure to methoxyflurane vapors. The possibility that methoxyflurane increases alcohol dehydrogenase-dependent oxidation of allyl alcohol to acrolein, the proposed toxic metabolite, was evaluated by measuring the rate of acrolein formation in the presence of allyl alcohol and liver cytosol. The effect of methoxyflurane on alcohol dehydrogenase activity in liver cytosol was also assessed by measuring the rate of NAD+ utilization in the presence of ethyl alcohol or allyl alcohol. Alcohol dehydrogenase activity and rate of acrolein formation were elevated in methoxyflurane-pretreated rats. The results suggest that a modest increase in alcohol dehydrogenase activity and rate of acrolein formation markedly enhances allyl alcohol-induced hepatotoxicity.