Allyl Alcohol Administration Research Articles

No Contribution of Multipotent Mesenchymal Stromal Cells to Liver Regeneration in a Rat Model of Prolonged Hepatic Injury

Multipotent mesenchymal stromal (MS) cells from adult bone marrow are a cell population that can be expanded to large numbers in culture. MS cells might be differentiated toward hepatocytes in vitro and thus are promising candidates for therapeutic applications in vivo. The efficacy of bone marrow-derived MS cells versus hepatocytes to contribute to liver regeneration was compared in a rat model of prolonged toxic hepatic injury. Liver damage was induced by injection of carbon tetrachloride (CCl(4)) or allyl alcohol (AA) with and without retrorsine (R) pretreatment. MS cells or hepatocytes of wild-type F344 rats were injected into dipeptidyl peptidase IV (DPPIV)-deficient syngeneic rats. Hepatocyte chimerism was higher after intraportal hepatocyte transplantation in the R/AA group (mean maximal cluster size [MCS] = 21 cells) compared with the R/CCl(4) treatment group (MCS = 18). No hepatocyte engraftment was outlined following post-transplant CCl(4) injection only, whereas mere AA injection resulted in small clusters of donor-derived hepatocytes (MCS = 2). Intraparenchymal injection of hepatocytes was associated with a MCS = 11 after R/AA treatment and a MCS = 6 after AA administration alone. Redistribution of MS cells to the liver was shown after intraportal and intraparenchymal injection. In contrast to hepatocyte transplantation, however, donor-derived DPPIV-positive cells could not be demonstrated in any recipient after MS cell transplantation. Data from the present study indicate that a well-defined population of MS cells obtained according to established standard protocols does not differentiate into hepatocytes in vivo when transplanted under regenerative conditions, in which the application of hepatocytes results in stable hepatic engraftment.

Therapeutic value of melatonin in an experimental model of liver injury and regeneration

Melatonin has marked antioxidant properties. The aim of the present study was to evaluate the therapeutic effect of melatonin on acute liver injury induced in rats by carbon tetrachloride (CCl4), allyl alcohol (AA) and their combination. A total of 108 male Wistar rats were divided into 12 experimental groups according to their treatment regimen (n = 5-10 rats in each group). Melatonin (100 mg/kg body weight, BW) was administered 6 hr (a) after a single dose of CCl4 (intragastrically 0. 66 mL/kg BW diluted 1:1 v/v with corn oil); (b) a single dose of AA (intraperitonealy, 0.62 mmol/kg BW 1:50 v/v in 0.9% saline solution); and (c) a combination of the above substances. Rats were sacrificed at 24 and 48 hr post-toxin administration and the therapeutic effect of melatonin was investigated by assessment of histopathological changes and lipid peroxidation alterations determined by measuring tissue malondialdehyde plus 4-hydroxy-nonenal (MDA + 4-HNE), plasma MDA and plasma levels of liver enzymes. The levels of a key antioxidant, glutathione (GSH), were measured in liver tissue homogenates. Hepatic necrosis was significantly reduced in the melatonin-treated rats 48 hr after administration of CCl4, AA and CCl4 + AA. The levels of hepatic enzymes in plasma were found to be significantly reduced at 24 and 48 hr in the CCl4 + AA treated rats after melatonin administration. Additionally, MDA and MDA + 4-HNE concentrations were significantly reduced at 24 and 48 hr time-points in all groups that received melatonin. GSH levels were decreased in liver after the toxic substances administration, whereas melatonin reversed this effect. In conclusion, a single dose of melatonin decreased hepatic injury induced by CCl4, AA and CCl4 + AA. The inhibition of the oxidative stress and therefore lipid peroxidation by melatonin in CCl4 and AA administered animals, may constitute the protective mechanism of melatonin against acute liver injury.

Protective effect of Phyllanthus fraternus against allyl alcohol-induced oxidative stress in liver mitochondria

The effect of administration of allyl alcohol on the oxidative stress and the protective effect due to administration of an aqueous extract of Phyllanthus fraternus against allyl alcohol-induced damage in liver mitochondria were studied. When rats were treated with allyl alcohol, the rate of mitochondrial respiration was decreased significantly with both NAD +- and FAD-linked substrates. The respiratory control ratio, an index of membrane integrity and the P/O ratio, a measure of phosphorylation efficiency also decreased significantly. There was a significant increase in the lipid peroxide level and the protein carbonyl content. A significant decrease was observed in the total sulphydryl groups and a significant increase in the generation of superoxide radicals. Administration of rats with an aqueous extract of Phyllanthus fraternus (100 mg/kg) prior to allyl alcohol administration showed protection of 72, 40 and 80% using glutamate + malate (NADH oxidation) and 77, 54 and 20% using succinate as substrate on state 3, RCR and P/O ratio, respectively. The protection on lipid peroxide level was 88 and 91% in homogenate and mitochondria, respectively. In case of protein carbonyls, total sulphydryl groups and on the generation of superoxide radicals the protection was 99, 59 and 53%, respectively.

Improvement of Mortality Rate and Decrease in Histologic Hepatic Injury After Human Cord Blood Stem Cell Infusion in a Murine Model of Hepatotoxicity

Background and aims Because of their plasticity potential local and systemic application of cord blood stem cells may represent excellent candidates for cell-based therapeutic strategies in toxic liver injuries. It is already known that intraperitoneal administration of hematopoietic stem cells provides rapid liver homing in animal models of hepatic injury. We sought to assess the efficacy of a hematopoietic stem cell infusion to decrease the histologic damage and the mortality rate of animals previously damaged by allyl alcohol. Material and Methods NOD/SCID mice were divided into two groups. (1) animals treated by intraperitoneal administration of allyl alcohol and (2) animals treated with allyl alcohol and 24 hours later with an intraperitoneal infusion of human cord blood cells. Flow cytometry, histology, immunohistochemistry, and RT-PCR were performed to monitor human cell engraftment by evidences of human hepatic markers. Results Human stem cells were able to transdifferentiate into hepatocytes, improve liver regeneration after damage, and reduce the mortality rate even when requiring qualitative and quantitative differences in the transdifferentiation processes. The mortality rate deacreased from 70% to 20%, with a significant improvement in the histologic findings. Conclusion We demonstrated that the infusion of hematopoietic stem cells into the liver in the early stage of damage might initiate endogenous hepatic tissue regeneration that oppose the injury inflicted by toxicants.

The Effects of Allyl Alcohol-induced Cell Proliferation for Detection of Initiation Activities of Chemicals in Rat Liver.

The effect of allyl alcohol (AA) administration on the induction of glutathione S-transferase placental form (GST-P) positive foci in medium term liver bioassay was investigated for the detection of initiation activities. In experiment I, the cell kinetics of rat liver after AA administration (0.1 ml/kg, i.g.) was analyzed by the 5-bromo-2'-deoxyuridine (BrdU) labeling method. Cytochrome P450 (CYP) 2E1 protein, which is involved in the bioactivation of 1,2-dimethylhydrazine (DMH), was quantificated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the immunohistochemical localization of CYP2E1 was also examined. In experiment II, the induction of GST-P positive foci by DMH was evaluated in a modified in vivo five-weeks initiation assay model using AA treatment to induce cell proliferation. AA induced periportal necrosis and led to regenerative proliferation. High BrdU labeling indices were observed from 24 h to 48 h (5-6%). CYP2E1 protein contents decreased transiently to approximately 40% of control after AA administration, but subsequently recovered to the control level. Immunohistochemically, CYP2E1 was localized in the centrilobular area each time, and the staining pattern was constant. The numbers and areas of GST-P positive foci were highly induced in the animals given DMH at 12 h after AA administration, compared to before the high BrdU labeling term. There was a correlation between the kinetics of cell proliferation and the induction of GST-P positive foci. Although CYP2E1 decreased after AA treatment, it is likely that the enzyme remained enough to metabolize DMH. These results suggest that AA-induced cell proliferation is an effective proliferative stimulus in medium-term initiation assay.

Influence of Caffeine on Allyl Alcohol-Induced Hepatotoxicity in Rats* I. In Vivo Study

Cotreatment of rats with a low hepatotoxic dose (30.7 mg/kg, i.p.) of allyl alcohol (AA) and a higher, but nontoxic, dose (150 mg/kg, oral) of caffeine (CF) potentiated the hepatotoxicity of AA. This was verified by significantly higher levels of plasma alanine aminotransferase (ALT) activity and histopathologically greater severity of lesions in the periportal hepatocytes than those due to AA alone. Treatment of rats with 4-methylpyrazole (4-MP) (0.5 mmol/kg, i.p.) (an inhibitor liver alcohol dehydrogenase) for 30 minutes, followed by similar cotreatment with AA and CF, completely prevented the elevation of plasma levels of ALT and histological damage induced by cotreatment with CF and AA 24 hours following their administration. Severe liver damage induced by cotreatment with CF and AA was further, markedly enhanced by phenobarbital pretreatment (80 mg/kg, i.p., 3 days). Thus, extensive necrosis of periportal hepatocytes was noted, as well as edema and accumulation of inflammatory cells in the necrotic foci caused by such pretreatment. The depression of hepatic nonprotein sulfhydryls resulting from CF plus AA was much more severe than that caused by AA or CF alone and appeared as early as 30 minutes after administration. However, much less marked depletion of protein thiols was observed following similar treatments. Significant increase in lipid peroxidation (as measured by melondialdehyde [MDA] formation) was also observed in rat liver but only 24 hours after administration. The production ofMDA in the rat liver was significantly higher after administration of AA plus CF than after administration of AA alone. Pretreatment of rats with phenobarbital further significantly enhanced the formation of 2,4-dinitrophenylhydrazine (DNP)-reactive metabolite(s) (measured as DNP-acrolein adduct equivalents) in rat liver induced by AA (30.7 mg/kg) plus CF (150 mg/kg) within 1 hour following such treatment. Cotreatment with AA and a higher dose of CF resulted in significantly higher excretion of urinary thioethers or mercapturic acids than in rats treated with AA alone. Thus, these data suggest that an increased bioactivation pathway of acrolein involving a P450 mixed-function oxidase system caused by CF may be involved in such potentiating effects of CF on AA-induced hepatotoxicity in rats.

Toxicant-inflicted injury and stimulated tissue repair are opposing toxicodynamic forces in predictive toxicology.

These studies were designed to investigate the dose response for liver injury and tissue repair induced by exposure to four structurally and mechanistically dissimilar hepatotoxicants, individually and as mixtures. The objective was to illuminate the impact of the extent and timeliness of tissue repair on the ultimate outcome of toxicity. Dose-response relationships for trichloroethylene (TCE), allyl alcohol (AA), thioacetamide (TA), and chloroform alone or as mixtures were studied. Male Sprague-Dawley rats (200-250 g) received a single intraperitoneal injection of individual toxicants as well as mixtures of these toxicants. Liver injury was monitored by plasma enzyme (ALT and SDH) levels and histopathology. Tissue regeneration was measured by [3H]thymidine incorporation into hepatic nuclear DNA. Individually, TCE, TA, and AA administration, over a 10- to 12-fold dose range, revealed a dose-related increase in injury as well as tissue repair up to a threshold dose. Beyond this threshold, tissue repair was delayed and attenuated, and liver injury progressed. Mixtures of the four chemicals at the higher doses used in individual dose-response studies resulted in 100% mortality. Hence, mixtures at the lower two doses were selected for further study. Additional lower doses were also included to better understand the dose-response relationship of mixtures. Results of these studies support the observations of individual chemicals. Higher and sustained repair was observed at low dose levels. These studies show that the extent of injury at early time points correlates well with the maximal stimulation of the opposing response of tissue repair. It appears that the toxicity of the mixture employed in these studies is roughly additive and correlates well with tissue repair response. These initial studies suggest that a biologically based mathematical model can be constructed and tested to extrapolate the outcome of toxicity from a given dose of individual compounds as well as their mixtures, where the responses measured are injury on the one hand and compensatory tissue repair on the other.

Protective effects of Propolis extract on allyl alcohol-induced liver injury in mice

Potential protective effects of ethanolic extract of Cuban red propolis against toxicity induced by allyl alcohol in mice was investigated. Propolis at doses of 25, 50 and 100 mg/i.p. significantly decreased the activity of alanine amino transferase (EC 2.6.1.2) in serum and the levels of mal-ondialdehyde in mouse liver after induction with a dose of 64 mg/kg of allyl alcohol. However, propolis did not increase the concentration of reduced glutathione in mouse liver which is depleted by allyl alcohol. Propolis also reduced liver damage induced by allyl alcohol in mice. This effect was observed by electron microscopy. The hepatoprotective effects of propolis were dose-dependent and they were produced when propolis was administered 30 min before allyl alcohol administration. It is indicated that the ethanolic extract of red propolis exerts potential hepatoprotective effects in this experimental model which is probably caused by antioxidative properties (e.g. scavenging action against oxygen radicals) of this extract.

Effect of verapamil on allyl alcohol hepatotoxicity.

The effects of verapamil, a calcium channel blocker, on allyl alcohol (AA) hepatotoxicity were studied in vivo. AA administration induced an increase of serum alanine aminotransferase (ALT) concentration and liver necrosis by means of glutathione (GSH) depletion. Pretreatment with verapamil reduced the increase of ALT in plasma and the morphological signs of necrosis induced by AA administration. Verapamil did not affect GSH levels by itself but prevented the decrease of the tripeptide by AA. In vitro, but not in vivo, verapamil inhibited the activity of alcohol dehydrogenase (ADH), the key enzyme in the conversion of AA into the toxic metabolite acrolein. These data indicate that verapamil protects against AA toxicity, probably by preventing the production of acrolein, its reactive metabolite.

Depletion of neutrophils and modulation of Kupffer cell function in allyl alcohol-induced hepatotoxicity

The roles of neutrophils (PMNs) and Kupffer cells in hepatotoxicity caused by allyl alcohol in rats in vivo were examined. To test the involvement of PMNs in the response to allyl alcohol, the number of circulating PMNs was reduced to < 500/μl by treatment with immunoglobulin (Ig) isolated from serum of rabbits treated with rat PMNs (anti-PMN Ig). Rats received anti-PMN Ig or control Ig 6 h before and 6 h after administration of allyl alcohol (40 mg/kg, i.p.). Hepatotoxicity was assessed 18 h after allyl alcohol administration. In rats pretreated with control Ig, treatment with allyl alcohol resulted in hepatotoxicity as evidenced by an increase in the activity of alanine aminotransferase (ALT) in serum. Neutropenia did not attenuate hepatic injury caused by allyl alcohol. Leukopenia induced by pretreatment with cyclophosphamide also did not influence the hepatotoxic response to allyl alcohol. To inhibit the function of Kupffer cells, animals were treated with gadolinium chloride (GdCl 3; 10 mg/kg, i.v.) 24 h before administration of allyl alcohol. This dose of GdCl 3 decreased in situ clearance of colloidal carbon by 64%. Despite the inhibition of Kupffer cell function, ALT activity in serum was not different in allyl alcohol-treated rats pretreated with GdCl 3 and those pretreated with saline vehicle. Histopathologic evaluation of the livers confirmed a lack of protective effect of GdCl 3. These results suggest that neither neutrophils nor Kupffer cells play a major role in liver injury due to allyl alcohol.

The cellular reproduction in physiological and reparative liver regeneration

The liver regeneration of male rats was examined autoradiographically under physiological and reparative conditions. The reparative regeneration was induced by a single injection of allylalcohol intraperitoneally. In both forms of regeneration a displacement of tritiated thymidine-marked hepatocytes from the periportal field to the perivenous field of the liver acinus could be recognized. The velocity of the cell migration after allylalcohol administration was higher than under physiological conditions. Physiological and reparative liver regeneration do not exclude each other but obviously coexist. A more intensively to be examined hepatocellular stem cell concept gains importance.

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 μ m) on isolated hepatocytes was studied using cells maintained at either 95 or 21% O 2. 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 O 2 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 (GdCl 3, 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 GdCl 3 24 hr prior to allyl alcohol injection. Thus, O 2-dependent hepatic necrosis caused by allyl alcohol involves the presence of Kupffer celis. Since GdCl 3 did not prevent toxicity in the perfused liver, circulating blood elements may also contribute to injury of the liver by allyl alcohol in vivo.

Iron release and erythrocyte damage in allyl alcohol intoxication in mice

Allyl alcohol administration in a toxic dose (1.5 mmol/kg) to starved mice causes the development of hemolysis in nearly 50% of the animals. Malonic dialdehyde (MDA) appears in plasma of the animals showing hemolysis. The treatment of mice with desferrioxamine after allyl alcohol intoxication completely prevents lipid peroxidation and hemolysis, suggesting the involvement of iron in the allyl alcohol-induced erythrocyte damage. Erythrocytes obtained from intoxicated mice before the development of hemolysis show, upon incubation, release of iron, lipid peroxidation and lysis. Studies carried out with reconstituted systems of erythrocyte lysates, containing ghosts and different fractions of erythrocyte cytosol and incubated in the presence of acrolein (the major metabolite of allyl alcohol), strongly suggest that iron is released from hemoglobin. This iron appears to promote lipid peroxidation which is accompanied by erythrocyte lysis. Thus, the allyl alcohol-induced hemolysis appears to be a model for iron delocalization from iron stores.

Hepatotoxin-induced hypertaurinuria: a proton NMR study

The urinary excretion of taurine by rats after dosing with various hepatotoxins has been investigated by 1H NMR spectroscopy. After single hepatotoxic doses of hydrazine, carbon tetrachloride, 1-naphthylisothiocyanate, or thioacetamide there was biochemical and histopathological evidence of hepatic damage. Proton NMR spectroscopy of the urine collected for 24 h after dosing from these animals revealed a marked elevation in taurine (control 11.9 mumole/h/kg) after dosing with thioacetamide (42.2 mumole/h/kg), carbon tetrachloride (52.5 mumole/h/kg), 1-naphthyl-isothiocyanate (80.4 mumole/h/kg) and hydrazine (52.9 mumole/h/kg). After allyl alcohol administration there was no increase in taurine excretion (7.5 mumol/h/kg). The excretion of taurine after hydrazine administration was dose related. High resolution proton NMR spectroscopic analysis of urine also revealed resonances from several metabolites of hydrazine, an N-acetylcysteine conjugate of allyl alcohol, and acetamide as a metabolite of thioacetamide after dosing with the respective compounds. Changes in endogenous substances that may be related to the pathological events were also detected, such as a decrease in the excretion of 2-oxoglutarate and citrate after both hydrazine and carbon tetrachloride administration. The results confirm that proton NMR spectroscopic analysis of urine is a powerful analytical tool for the evaluation and study of toxic substances. Furthermore, measurement of urinary taurine may provide a non-invasive indicator of acute hepatic damage with certain classes of hepatotoxins.

Allyl alcohol-induced hemolysis and its relation to iron release and lipid peroxidation

Allyl alcohol administration to starved mice produced, along with liver necrosis, a high incidence (about 50%) of hemolysis. A marked decrease in erythrocyte glutathione (GSH) was seen in all the intoxicated animals. Such a decrease was significantly higher in the animals showing hemolysis. In these animals a substantial amount of malonic dialdehyde (MDA) was detected in plasma and a marked decrease in arachidonic and docosahexaenoic acids was found in erythrocyte phospholipids. These data suggest that the allyl alcohol-induced hemolysis is mediated by lipid peroxidation. In vitro studies have shown that the addition of acrolein to mouse erythrocytes produces a dramatic GSH depletion, which is followed by the appearance of lipid peroxidation and, after an additional 30 min of incubation, by the development of hemolysis. Prevention of lipid peroxidation by an antioxidant (Trolox C) or an iron chelator (desferrioxamine, DFO), prevented hemolysis even if the erythrocyte GSH level was dramatically decreased. In vitro, allyl alcohol and acrylic acid were ineffective in inducing GSH depletion, lipid peroxidation and hemolysis. Studies of possible induction of lipid peroxidation in erythrocytes showed that a progressive increase in “free” (desferal chelatable) iron occurs in the erythrocytes during the incubation with acrolein. It seems, therefore, that a release of iron from iron-containing complexes occurs in acrolein-treated erythrocytes and that such “free” iron promotes lipid peroxidation.

Activation of the microsomal glutathione- s-transferase and reduction of the glutathione dependent protection against lipid peroxidation by acrolein

Allyl alcohol is hepatotoxic. It is generally believed that acrolein, generated out of allyl alcohol by cytosolic alcohol dehydrogenase, is responsible for this toxicity. The effect of acrolein in vitro and in vivo on the glutathione (GSH) dependent protection of liver microsomes against lipid peroxidation, and on the microsomal GSH- S-transferase (GSH-tr) in the rat was determined. In vitro incubation of liver microsomes with 5 mM acrolein for 30 sec resulted in a 2-fold activation of the GSH-tr. This activation probably proceeds via alkylation of the thiol group of the GSH-tr. In vivo administration of 1.1 mmol allyl alcohol/kg to rats did also result in a 2-fold stimulation of the GSH-tr activity. Administration of 375 mg pyrazole/kg, an inhibitor of the alcohol dehydrogenase, thus reducing the acrolein formation, prevented the in vivo stimulation of GSH-tr by allyl alcohol. This indicates that the activation of GSH-tr in vivo by allyl alcohol probably also proceeds via alkylation of the thiol group of the GSH-tr by acrolein. GSH protects liver microsomes against lipid peroxidation, probably via a free radical reductase that reduces vitamin E radicals at the expense of GSH. Incubating liver microsomes for 30 min with 0.1 mM acrolein reduced the GSH dependent protection against lipid peroxidation, probably because an essential thiol group(s) on the free radical reductase is alkylated. In vivo administration of allyl alcohol did not reduce the GSH dependent protection of the microsomes. Probably the thiol group(s) located on the free radical reductase is less accessible or less reactive than the thiol group on the GSH-tr. After administration of allyl alcohol we found no evidence for in vivo lipid peroxidation. Therefore we could not evaluate the importance of the GSH dependent protection against lipid peroxidation in vivo.

The role of acrolein in allyl alcohol-induced lipid peroxidation and liver cell damage in mice

Male NMRI mice were fed a sucrose diet for 48 hr in order to reduce the hepatic glutathione content and to level off its diurnal variation. After administration of allyl alcohol (AA: 1.1 mmol/kg), hepatic glutathione (24.3 ± 7.0 nmol GSH/mg protein) was almost totally lost within the first 15min (<0.5 nmol GSH/mg protein). Subsequently, a massive lipid perioxidation was observed, i.e. the animals exhaled 414 ± 186 nmol ethane/kg/hr compared to 0.9 ± 0.8 of controls, and the hepatic TBA- reactive compounds had increased from 55 ± 16 pmol/mg protein in controls to 317 ± 163 after 1 hr. Concomitantly, a 40–45% loss of the polyunsaturated fatty acids (arachidonic and docosahexaenoic acid) in the liver lipids was observed. About 80% of the cytosolic alcohol dehydrogenase activity and about 50% of the microsomal P450-content were destroyed. In vivo-inhibition of alcohol dehydrogenase by pyrazole or induction of aldehyde dehydrogenase by phenobarbital abolished AA-induced liver damage as well as glutathione depletion and lipid peroxi- dation, while inhibition of aldehyde dehydrogenase by cyanamide made a subtoxic dose of AA (0.60 mmol/kg) highly toxic. These results strongly favour the importance of acrylic acid formation as an additional detoxification pathway. Enhanced hepatic levels of glutathione protected in vivo against the damaging effects of AA. Depletion of the liver glutathione content by phorone or diethylmaleate alone caused marginally enhanced lipid peroxidation (phorone) but no liver cell damage. Mono- oxygenase inhibitors (metyrapone, diethyldithiocarbamate, α-naphthoflavone) or an inducer (benz( a)pyrene) did not affect AA-induced toxicity. The ferric iron chelator desferoxamine- methanesulfonate prevented AA-induced lipid peroxidation and liver cell damage in vivo. In vitro, acrolein alone failed to initiate lipid peroxidation in soy bean phospholipid liposomes or in mouse liver microsomes. Thus, acrolein not only impairs the glutathione defense system but also directly destroys cellular proteins and evokes lipid peroxidation by an indirect iron-depending mechanism.

Hepatotoxicity due to allyl alcohol in deermice depends on alcohol dehydrogenase.

The role of alcohol dehydrogenase in the hepatic necrosis due to allyl alcohol was studied in two strains of the deermouse, Peromyscus maniculatus. Mice of the alcohol dehydrogenase-negative (AdhN) strain which lack alcohol dehydrogenase activity were resistant to allyl alcohol toxicity. In contrast, dose-dependent necrosis of periportal regions of the liver and increases in plasma levels of lactate dehydrogenase, sorbitol dehydrogenase and SGOT were observed in plasma from alcohol dehydrogenase-positive deermice (AdhF) 24 hr following administration of allyl alcohol (21 to 84 mg per kg). Half-maximal damage to periportal areas was observed with about 52 mg per kg allyl alcohol. Thus, these data demonstrate that metabolism of allyl alcohol to acrolein by alcohol dehydrogenase is obligatory for the hepatotoxicity of allyl alcohol.

Alcohol dehydrogenase: A new sensitive marker of hepatic centrilobular damage

To determine whether serum alcohol dehydrogenase (ADH) activity reflects hepatic damage of centrilobular region (zone 3), the rats were given either bromobenzene (BB) or allyl alcohol (AA) IP to produce the pericen tral or periportal necrosis respectively. After AA or BB serum alanine aminotransferase (ALT) activity showed no significant difference between the two groups. By contrast, serum ADH and glutamate dehydrogenase (GLDH) activities were elevated preferentially in the BB treated rats. However, AA administration to rats also resulted in a significant increase in GLDH activity, whereas ADH activity was only slightly elevated when compared to controls. Moreover, acute ethanol administration to rats resulted in a significant elevation of the serum ADH activity, whereas serum GLDH and ALT activities remained normal. These data suggest that serum ADH activity appears to be a sensitive and specific marker of hepatic centrilobular damage.

Quantitative liver functions after administration of allyl alcohol to rats.

In rats a single dose of allyl alcohol (100 microliter per kg body weight) was given to produce periportal liver damage. Prothrombin index was reduced to a minimum after 12 hours and reestablished after 24 hours. The galactose elimination capacity was not changed. Hepatic glutathione content was unchanged for the first 24 hours but was then elevated twofold. Microsomal p-nitro-anisole demethylation showed a slight initial increase and a subsequent reduction. The pattern of these changes is similar to that seen after centrilobular liver damage from acetaminophen overdose (Poulsen et al. 1981 a; Poulsen et al., unpublished results), with the exception that the latter causes glutathione depletion. This indicates that in chemical liver damage ribosomal function, e.g. protein synthesis and drug hydroxylation, is more vulnerable than cytosolic phosphorylation of carbohydrate.