Dose Of Carbon Tetrachloride Research Articles

Iron overload facilitates hepatic fibrosis in the rat alcohol/low-dose carbon tetrachloride model

The role of iron deposition in initiating hepatic fibrosis in iron overload disorders is not clearly established, and it is becoming increasingly recognized that iron may be interacting with other potential liver-damaging agents. The authors therefore examined the interplay of iron and alcohol in rats administered subtoxic doses of carbon tetrachloride (CCL 4) vapor at 20 ppm in customized chambers. At birth, the offspring of seven pregnant Porton rats were divided into two groups: one group was fed a normal rat chow diet and the other a diet supplemented with 3% (w/w) carbonyl iron for 10 weeks after weaning. In this latter group, the mothers were fed an iron supplement while breastfeeding. At 10 weeks, the animals from the first group (normal chow) were divided into two groups of six animals and fed a LieberDeCarli liquid diet with daily exposure to CCL 4 vapor: group 1, liquid diet + CCL 4; group 2, liquid diet + alcohol 150 kcal/I + CCL 4. The animals from the second iron-supplemented group were divided into two groups of six animals and fed a liquid diet with 3% (w/v) carbonyl iron and exposed to CCL 4 vapor for 10 weeks: group 3, liquid diet + iron + CCL 4 group 4, liquid diet + iron + alcohol supplement + CCL 4. Two animals from each group of six had a liver biopsy at 4, 6, and 8 weeks, and all animals were killed after 10 weeks of CCL 4 exposure. After the first 10-week iron loading period, the rats fed the carbonyl iron-supplemented diet had a 10-fold elevation in hepatic iron concentration. In the second 10-week (CCL 4 exposure) period, fibrosis was scored on a four-point scale in each liver biopsy and in all animals at 10 weeks. At 10 weeks, the animals exposed to iron and alcohol in addition to CCL 4 all had an established or developing cirrhosis with the development of fibrosis apparent at 4 weeks. Animals in the other groups had markedly less fibrosis, with none seen in the control group up to 10 weeks. Thus, the addition of iron to alcohol facilitates the development of fibrosis in animals exposed to subtoxic doses of CCL 4 vapor. This model should allow a more detailed analysis of the mechanism(s) underlying this process.

Iron overload facilitates hepatic fibrosis in the rat alcohol/low-dose carbon tetrachloride model

The role of iron deposition in initiating hepatic fibrosis in iron overload disorders is not clearly established, and it is becoming increasingly recognized that iron may be interacting with other potential liver-damaging agents. The authors therefore examined the interplay of iron and alcohol in rats administered subtoxic doses of carbon tetrachloride (CCl4) vapor at 20 ppm in customized chambers. At birth, the offspring of seven pregnant Porton rats were divided into two groups: one group was fed a normal rat chow diet and the other a diet supplemented with 3% (w/w) carbonyl iron for 10 weeks after weaning. In this latter group, the mothers were fed an iron supplement while breastfeeding. At 10 weeks, the animals from the first group (normal chow) were divided into two groups of six animals and fed a Lieber-DeCarli liquid diet with daily exposure to CCl4 vapor: group 1, liquid diet+CCl4; group 2, liquid diet+alcohol 150 kcal/l+CCl4. The animals from the second iron-supplemented group were divided into two groups of six animals and fed a liquid diet with 3% (w/v) carbonyl iron and exposed to CCl4 vapor for 10 weeks: group 3, liquid diet+iron+CCl4; group 4, liquid diet+iron+alcohol supplement+CCl4. Two animals from each group of six had a liver biopsy at 4, 6, and 8 weeks, and all animals were killed after 10 weeks of CCl4 exposure. After the first 10-week iron loading period, the rats fed the carbonyl iron-supplemented diet had a 10-fold elevation in hepatic iron concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanistic studies on the potentiation of carbon tetrachloride hepatotoxicity by methamphetamine

Recent studies have shown that methamphetamine is capable of potentiating the hepatotoxicity of carbon tetrachloride in mice. In the present study, it was found that this potentiation is sensitive to changes in the timing of the methamphetamine dose relative to the administration of carbon tetrachloride. Potentiation of hepatotoxicity, measured using serum alanine aminotransferase (ALT) activity, was observed only if the dose of methamphetamine (15 mg/kg, i.p.) was given with, or 3 h after, the carbon tetrachloride dose (0.005 ml/kg i.p.). No increase in carbon tetrachloride hepatotoxicity was evident when methamphetamine was administered 3 h before the carbon tetrachloride dose, or when given 6 or more hours after carbon tetrachloride. Increased covalent binding of carbon tetrachloride to proteins and lipids, shown previously to occur when methamphetamine and carbon tetrachloride are administered together, was not observed when methamphetamine was administered 3 h after the carbon tetrachloride dose and could not, therefore, account for the increased toxicity resulting from this treatment regimen. Pretreatment with the Kupffer cell inhibitor gadolinium chloride (10 mg/kg i.v.) significantly diminished the potentiation of carbon tetrachloride hepatotoxicity by methamphetamine, suggesting that potentiation by methamphetamine involves, at least in part, a stimulation of Kupffer cells. Mice administered a methamphetamine pretreatment regimen known to induce behavioral sensitization displayed an enhanced potentiation of carbon tetrachloride hepatotoxicity i.e. the extent of potentiation by methamphetamine was increased and the methamphetamine dose required for potentiation was diminished. Mice pretreated with a methamphetamine sensitization regimen were also found to be more responsive to the effects of morphine to enhance carbon tetrachloride hepatotoxicity. These observations suggest that there are important CNS, as well as hepatic, components in the potentiation of carbon tetrachloride-induced liver injury by methamphetamine and perhaps other drugs.

Exacerbation of carbon tetrachloride-induced liver injury in the rat by methamphetamine

The effect of methamphetamine cotreatment on carbon tetrachloride-induced liver toxicity was examined in male Sprague-Dawley rats. Concurrent administration of methamphetamine was found to greatly increase the extent of liver injury resulting from carbon tetrachloride treatment, as indicated both by measurement of serum alanine aminotransferase (ALT) activity and from direct histopathologic examination. Concurrent administration of methamphetamine doses less than 10 mg/kg (i.p.), or administration of methamphetamine either before (−3 h) or after (3–9 h) the carbon tetrachloride dose, did not significantly increase liver injury from carbon tetrachloride. These observations indicate that the potentiation by methamphetamine of carbon tetrachloride hepatoxicity previously observed in the mouse also occurs in the rat, and that the timing of the methamphetamine and carbon tetrachloride doses is critical for the interaction.

Expression of clusterin (testosterone-repressed prostate message-2) mRNA during growth and regeneration of rat liver.

Clusterin has been used as a marker for apoptosis (often denoted "active" "or programmed" cell death) in the prostate, mammary gland and other solid organs. The protein is thought to be involved in membrane remodelling during separation of apoptotic cells from their vital neighbours and fragmentation into apoptotic bodies. In the present study, we have looked at the expression of clusterin during the growth and regression of rat liver induced by short term administration of the hepatomitogen, cyproterone acetate. The steady state level of clusterin mRNA, as measured by Northern and slot blot analysis, is low in control hepatocytes. Following administration of cyproterone acetate, the clusterin mRNA level is increased during both liver growth and regression. In situ hybridization reveals that clusterin is expressed in all hepatocytes, indicating that it is not confined to cell death by apoptosis. These results suggest that the gene product may be involved in maintaining membrane integrity, which is necessary during both mitosis and apoptosis. To determine whether clusterin mRNA is induced by membrane remodelling independent of either mitosis or apoptosis, we examined the expression of clusterin mRNA in the liver after a necrogenic dose of carbon tetrachloride. During the first 24-48 h of this time period, necrosis is the predominant form of cell death and liver regeneration starts after approximately 24 h. Elevated levels of clusterin mRNA are found as early as 12 h after carbon tetrachloride administration and persist for at least 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose‐Response Relationships in Hepatic Injury Produced by Alcohol and Carbon Tetrachloride

Dose-response relationships were examined for the production of hepatic fibrosis and cirrhosis by combined exposure of male Porton rats to alcohol and carbon tetrachloride. Alcohol was administered orally in Lieber-DeCarli liquid diet at levels of 75, 150, or 300 kcal/liter, giving mean daily intakes of 2.29, 4.61, and 8.16 g/kg/day, respectively. Carbon tetrachloride was administered by inhalation at concentrations of 10, 20, or 40 ppm, 6 hr/night, 5 nights/week. Liver biopsies were taken at intervals up to a maximum treatment period of 20 weeks. All four rats that received the high dose of both agents, and 1 of 4 that received the medium alcohol and high carbon tetrachloride treatments, were cirrhotic by 10 weeks. Two of the 4 rats that received the low alcohol and high carbon tetrachloride dose were cirrhotic at 20 weeks. Cirrhosis was not observed in rats that received the low or medium carbon tetrachloride dose, but some degree of hepatic fibrosis was observed in all treatment groups. Severity of fibrosis was significantly associated with both dose of alcohol and dose of carbon tetrachloride received. It is concluded that, in the alcohol-carbon tetrachloride rat model for chronic liver injury, both alcohol and carbon tetrachloride contribute to the response in a dose-related manner. Hepatic injury was observed even when relatively low doses of these agents are administered together.

Induction of beta-platelet-derived growth factor receptor in rat hepatic lipocytes during cellular activation in vivo and in culture.

A consistent response to liver injury is the activation of resident mesenchymal cells known as lipocytes (Ito, fat-storing cells) into a proliferating cell type. In cultured lipocytes, platelet-derived growth factor (PDGF) is the most potent proliferative cytokine, but requires the activation-dependent expression of its receptor protein (Friedman, S. L., and M. J. P. Arthur. 1989. J. Clin. Invest. 84:1780-1785); the role of PDGF receptor (PDGFR) in liver injury is unknown. We have examined PDGFR gene expression in freshly isolated lipocytes during liver injury and correlated these findings with a culture model of cellular activation. Whereas lipocytes from normal rats had no detectable transcript for the beta-PDGFR subunit, this mRNA was induced within 1 h after a dose of carbon tetrachloride (CCl4). In contrast, alpha subunit mRNA was detected in normal cells, but was unchanged after liver injury. Similar results were observed in lipocytes from bile duct-obstructed rats, although beta-PDGFR induction was less marked. By immunoblot, induction of beta-PDGFR protein in lipocytes isolated from CCl4-treated animals correlated with mRNA increases. In contrast to lipocytes, endothelial cells from normal liver expressed low levels of alpha- and beta-receptor subunit mRNA, which did not increase with injury. Using a beta-PDGFR antibody, receptor protein could be identified within fibrotic septa in CCl4-treated animals in regions where cells expressed proliferating cell nuclear antigen (PCNA). In cultured lipocytes activated by growth on uncoated plastic, beta-PDGFR transcripts appeared within 3 d after plating, which coincided with the onset of cellular proliferation. In contrast, quiescent cells in suspension culture had no detectable beta-PDGFR mRNA. These results indicate that beta-PDGF receptor induction by lipocytes is an early event during hepatic injury in vivo and in primary culture.

Expression of myc, fos and Ha-ras associated with chemically induced cell proliferation in the rat liver.

Events secondary to induced cell proliferation may play a role in the carcinogenic process. These studies investigated the expression of genes associated with growth control in response to two types of cell proliferation stimuli in the livers of male F344 rats. Regenerative hepatocyte proliferation after partial hepatectomy or a single dose of carbon tetrachloride, and mitogenic liver hyperplasia induced by a single dose of phenobarbital or WY-14,643 were assessed by thymidine incorporation and quantitative autoradiography. The expression of myc, fos, and Ha-ras was evaluated by Northern blot analysis of liver derived poly(A)+ mRNA from these same animals. After each treatment, the level of hepatocyte proliferation (labelling index 4-32%) was observed to peak between 24 and 48 h and return to control values by 8 days. In every case, a peak in myc expression was seen between 0.5 and 18 h depending on the proliferative stimulus treatment. A large peak in fos expression was seen at 0.5-2 h but only with the cytotoxic and regenerative proliferative treatments partial hepatectomy or carbon tetrachloride. A broad peak in Ha-ras expression was observed 12 to 36 h after each treatment. These data demonstrate transient expression of these genes following the synchronous induction of hepatocyte proliferation. The increased expression of fos upon treatment with cytotoxicants, but not mitogens, suggests different modes of growth regulation that may be important in understanding the induction of cell proliferation by these two types of agents.

In vivo and in vitro 31P magnetic resonance spectroscopic studies of the hepatic response of healthy rats and rats with acute hepatic damage to fructose loading.

The hepatic response to a fructose challenge for control rats, and rats subjected to an acute sublethal dose of carbon tetrachloride (CCl4) or bromobenzene (BB), was compared using dynamic in vivo 31P MRS. Fructose loading conditions were used in which control rats showed only a modest increase in hepatic phosphomonoester (PME), and a small decrease in ATP, Pi, and intracellular pH after fructose administration. Both CCl4 and BB-treated rats showed a much greater fructose-induced accumulation of PME than did controls. Trolox C, a free radical scavenger, prevented most of this PME increase. BB-treated rats, given sufficient time to recover from the hepatotoxic insult, responded to the fructose load similarly to controls. Liver aldolase activities of control, toxicant-treated rats, and toxicant plus Trolox C-treated rats correlated inversely with PME accumulation after fructose loading (correlation coefficient: -0.834, P < 0.05). Perchloric acid extracts of rat livers studied by in vitro 31P MRS confirmed that the PME accumulation after fructose loading is mainly due to an increase in fructose 1-phosphate. These studies are consistent with the aldolase-catalyzed cleavage of fructose 1-phosphate being rate-limiting in hepatic fructose metabolism, and that the CCl4 and BB treatment modify and inactivate the aldolase enzyme.

Induction of serum borne immunomodulatory factors in B6C3F1 mice by carbon tetrachloride: Exposure to carbon tetrachloride produces an increase in B-cell number and function

Carbon tetrachloride exposure in mice induces a serum associated immunosuppressive factor(s) that inhibits T-cell dependent immune responses. The objective of the present studies was to characterize the immunomodulatory activity of serum isolated from carbon tetrachloride-treated m mice on T-cell independent humoral immune responses. Direct addition of serum isolated from carbon tetrachloride-treated mice (500 mg/kg/day for 7 days) to naive spleen cell cultyres enhanced the antibody forming cell response to lipopolysaccharide as compared to serum from naive or vehicle-treated mice. Enhanced antibody forming cell responses were also observed when spleen cells isolated from carbon tetrachloride-treated mice were sensitized with this T-cell independent antigen 24 h, but not 48 h or 72 h, following exposure of mice to one dose of 500 or 1000 mg/kg of carbon tetrachloride. Additionally, spleen weight and spleen: body weight ratio were increased in mice sensitized in vivo with sheep red blood cells 24 h after exposure to a single dose of carbon tetrachloride (500 or 1000 mg/kg) as compared to naive antigen sensitized mice and mice sensitized 48 and 72 h after exposure to carbon tetrachloride. Fluorescence activated cell sorting analysis indicated that daily exposure to carbon tetrachloride (250 or 500 mg/kg for 7 days) increased the percentage of B-cells in the spleen without altering the number of T H-cell or T C/S cell populations. Taken together, these results suggest that exposure to carbon tetrachloride induces a serum borne factor(s) that produces a modest increase in the functional activity and number of B-cells in the spleen.

Expression of platelet-derived growth factor in a model of acute liver injury.

Platelet-derived growth factor has been shown to play an important role in the repair process after acute tissue injury and in the pathogenesis of several fibrogenic disorders. The aim of this study was to evaluate whether increased expression of platelet-derived growth factor and its beta-receptor subunit occurs in a model of acute liver injury. Male Sprague-Dawley rats were given a single intragastric dose of carbon tetrachloride and killed at intervals of 24, 48 and 72 hr and 1 wk. Control animals were included in each group. Platelet-derived growth factor-B chain mRNA expression, analyzed by RNase protection assay, was not detectable in control samples or in samples obtained 24 hr or 1 wk after carbon tetrachloride. However, the presence of protected fragments of 130 kb was clearly detected after 48 hr and was still present, although less abundant, after 72 hr. The distribution of platelet-derived growth factor protein in liver tissue sections, evaluated by immunohistochemistry, was restricted to centrilobular veins and portal tracts in normal liver. In carbon tetrachloride-treated rats, prominent staining was observed in areas corresponding to hepatocellular necrosis and inflammatory infiltration. This feature, already present at 24 hr after carbon tetrachloride, became more marked at 48 hr with a gradual resolution after 72 hr. The expression of platelet-derived growth factor-receptor beta-subunit mRNA, evaluated by in situ hybridization, was markedly increased after carbon tetrachloride with a peak at 24 hr and was mainly localized over mesenchymal cells in the hepatic sinusoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective action of putrescine against rat liver injury.

The hepatoprotective action of orally dosed putrescine was investigated using rat models of liver injury. When rats received putrescine orally soon after a dose of carbon tetrachloride or D-galactosamine, deranged serum alanine aminotransferase values and prothrombin times were significantly attenuated compared with control levels, with improved histologic extent of liver injury. Putrescine addition to the medium of rat hepatocytes in primary culture reduced cell killing induced by D-galactosamine or the membrane detergents chenodeoxycholic acid and Triton X-100. Similar reduction was seen in cells exposed to tert-butyl hydroperoxide (TBHP), an agent producing cell death through lipid peroxidation, with attenuation of cellular malondialdehyde content. Putrescine also significantly attenuated the extent of increased plasma membrane microviscosity as assessed with 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene in TBHP-treated cells. These results suggest that orally given putrescine protects against liver injury. Plasma membrane stabilization and reduction of lipid peroxidation may contribute to this hepatoprotection.

Hepatoprotective Effects of Taiwan Folk Medicine: Ixeris chinensis (Thunb.) Nak. on Experimental Liver Injuries

The hepatoprotective effects of Ixeris chinensis (Thunb.) Nak. were studied on acute hepatitis induced in mice by a single dose of carbon tetrachloride (31.25 microliters/kg, ip) or acetaminophen (600 mg/kg, ip), and in rats by a single dose of beta-D-galactosamine (188 mg/kg, ip). Hepatoprotective activity was monitored by estimating the serum transaminases (SGOT and SGPT) levels and histopathological changes in the livers of experimental animals. The Ixeris chinensis (Thunb.) Nak. extracts significantly inhibited the acute elevation of serum transaminases. Histopathologically, the crude I. chinensis extract significantly ameliorated hepatotoxin-induced histopathological changes in the livers of experimental animals. All pharmacological and histopathological effects of Ixeris chinensis (Thunb.) Nak. were compared with Bupleurum chinense DC., which has been previously reported as a treatment herb for hepatitis.

Induction of serum-borne immunomodulatory factors in B6C3F1 mice by carbon tetrachloride. I. Carbon tetrachloride-induced suppression of helper T-lymphocyte function is mediated by a serum borne factor

Following carbon tetrachloride-induced liver injury, hepatotrophic factors are synthesized and released into the serum to facilitate the regeneration of damaged hepatic tissue. We investigated the possibility that immunosuppression could be mediated through induction of a serum factor(s) because in vivo exposure of B6C3F1 mice to carbon tetrachloride selectively inhibits T-cell-dependent immune responses. Addition of mouse serum (5% by volume) obtained from mice treated with carbon tetrachloride (250 or 500 mg/kg/day for 7 days) to naive spleen cell cultures markedly suppressed the sheep red blood cell antibody-forming cell response compared to controls ( P < 0.01). Immunosuppression was observed in mice sensitized with sheep red blood cells 48 h, but not 24 or 72 h, following one dose of carbon tetrachloride (1000 mg/kg). Only serum isolated from mice 48 h following exposure to a single dose of carbon tetrachloride (1000 mg/kg) suppressed the antibody-forming cell response when added in vitro to spleen cell cultures. Biodistribution studies using [ 14C]-labelled carbon tetrachloride demonstrated that accumulation of the [ 14C]-label was primarily associated with excretory organs (liver, kidneys and lungs) but not with the serum, red blood cells, or spleen. Surprisingly, 24 and 48 h following exposure to [ 14C]-labelled carbon tetrachloride, an increase in radioactivity was detected in the thymus. The distinct profile immunosuppressive activity associated with serum isolated from carbon tetrachloride-treated mice and the biodistribution studies clearly demonstrating a negligible amount of carbon tetrachloride or metabolites in the serum strongly implicate the role of a carbon tetrachloride-induced serum borne immunosuppressive factor.

Variation in expression of genes used for normalization of Northern blots after induction of cell proliferation.

Quantitative knowledge of gene expression can provide valuable information for understanding the action of chemicals that alter cell proliferation and cancer. Accurate quantification of mRNA levels requires the normalization of the gene of interest to a gene with transcriptional levels that do not vary through the cell cycle or with a particular treatment. Changes in expression were examined in proliferating or non-proliferating rat liver for three constitutively expressed 'housekeeping' genes commonly used to normalize mRNA levels from Northern blots. In addition, a direct method of quantifying poly(A)+ mRNA by hybridization with a radiolabelled polythymidylate--poly(T)--probe was compared with traditional methods. Hepatocyte cytolethality and a subsequent wave of hepatocyte proliferation were induced in male Fischer-344 rats by treatment with a single gavage dose of carbon tetrachloride. Induced cell proliferation peaked at 48 h after treatment. Expression of the housekeeping genes actin, glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) and albumin, as well as the proto-oncogene H-ras, was determined by Northern blot analysis at times from 0.5 h to 4 days after treatment. Time-dependent changes were observed in the expression of these genes relative to the levels observed in the untreated control animals. Actin expression peaked at 3.4-fold over control and GAPDH expression was increased by 1.9-fold over control. Albumin mRNA levels varied the least, 1.4-fold over control, indicating that this gene is more appropriate than actin or GAPDH for normalization of proto-oncogene expression under experimental conditions that induce cell proliferation in rat liver. The direct quantification of poly(A)+ mRNA using a poly(T) probe was not influenced by the induction of cell proliferation. This method may be useful when the expression of housekeeping genes is affected by treatment.

Time course of hepatic injury and recovery following coadministration of carbon tetrachloride and trichloroethylene in Fischer-344 rats.

Simultaneous administration of trichloroethylene (TCE), at an oral dose of 0.5 ml/kg, resulted in a marked potentiation of liver injury caused by an oral dose of carbon tetrachloride (CCl4, 0.05 ml/kg). Hepatic glutathione levels were depressed at 24 hr only in the rats given TCE and CCl4. Using serum enzyme (ALT and SDH) as indicators of hepatotoxicity, potentiation of CCl4-injury was most apparent at 24 hr. Upon histological examination of H&E stained liver sections, the differences between livers obtained from TCE and CCl4-treated rats versus CCl4-treated rats were most apparent at later time points (48 and 72 hr). At 48 hr after CCl4, livers showed a distinctive and uniform pattern of injury with regeneration features predominating over necrosis. At this time, livers from TCE and CCl4-treated rats were characterized by extensive zone 3 coagulative necrosis. Inflammatory infiltrations were less prominent. At 72 hr, morphological features of livers from TCE and CCl4 rats were similar to those from rats given CCl4 alone at 48 hr. From the results obtained, it appears that the regenerative activity of the liver may be delayed in rats simultaneously administered TCE and CCl4 as compared to rats administered only CCl4.

Hepatic fibrosis as a predictor of hepatic regenerative activity after partial hepatectomy in the rat

Liver regeneration is an essential component of the recovery period after partial hepatectomy. Unfortunately, tests that accurately predict regenerative activity in the postoperative period have yet to be described. This study was designed to determine whether the extent of hepatic fibrosis correlates with liver regeneration activity after partial hepatectomy in rats with carbon tetrachloride-induced liver disease. Two groups of adult male Sprague-Dawley rats (12 to 30/group) were treated for 20 to 22 wk with weekly intragastric doses of carbon tetrachloride or vehicle. All rats then underwent 70% hepatectomy while under ether anesthesia. Liver regeneration activity was determined at 24 and 48 hr by [3H]thymidine incorporation into DNA. Hepatic fibrosis was calculated at the time of partial hepatectomy by automated image analysis on Van Gieson-stained liver tissue. Although a significant inverse correlation was found between the extent of hepatic fibrosis and DNA synthesis when all rats were considered (carbon tetrachloride-treated and vehicle-treated) at 24 and 48 hr after partial hepatectomy (r = -0.4943 and -0.7396, respectively; p < 0.05), no such correlation existed when carbon tetrachloride-treated rats were considered independently (r = -0.3231 and -0.0910 at 24 and 48 hr, respectively). In conclusion, we believe that in diseased livers, preoperative quantitation of hepatic fibrosis on automated image analysis does not serve as a useful predictor of liver regeneration activity.

Inhibitory effect of noradrenaline on acute liver injury induced by carbon tetrachloride in the rat

The effect of exogenous noradrenaline (NA) on acute liver injury was investigated in rats receiving a single dose of carbon tetrachloride (CC1 4). Animals were divided into the following groups: (I) no treatment, used for plasma catecholamine assay; (II) received CC1 4 only; (III) treated with CC1 4 plus noradrenaline (NA). Plasma levels of catecholamine (CA) were elevated in both groups II and III, particularly in NA: average value at 33 h after the exposure of CC1 4 increased to 290-fold of the control in group II and to 513-fold in group III. Subsequently, the levels of NA decreased with time, and were comparatively well-preserved in the rats of group III. Hepatic changes observed in the animals of group II were as follows: destruction with reduced number in rough endoplasmic reticulum; destruction and disappearance of cristae in mitochondria, and numerous fat droplets (shown by electron microscopy); histologically observed marked centrilobular necrosis with steatosis followed by progression with time; and microangiographically demonstrated deranged intrahepatic microvasculature. By contrast, these changes were successfully prevented by NA treatment (group III). Furthermore, histologically observed centrilobular change was restored with time. It was concluded that, in a deranged state, NA takes a form quite dissimilar to ordinary state: Na exerts for hapatoprotective and is highly involved in liver injury.

Increased muscle protein catabolism caused by carbon tetrachloride hepatic injury in rats

This study was undertaken to determine the pathogenesis of muscle atrophy that frequently accompanies liver disease. Hepatic injury was induced in rats by giving weekly intragastric doses of carbon tetrachloride (CCl4) in combination with phenobarbital in the drinking water. Muscle protein catabolism was assessed during three stages of liver injury and compared with pair-fed controls: group A had hepatic necrosis and inflammation without significant fibrosis; group B had cirrhosis as well as necrosis and inflammation; and group C had cirrhosis with minimal necrosis and inflammation. In group A, vastus lateralis white muscle, which contained predominately fast glycolytic fibers, showed a significant increase in protein catabolic rates compared with pair fed controls (0.95 ± 0.05 nmol tyrosine released · mg−1 · 2 h−1 vs. 0.86 ± 0.04; P < 0.05). In group B, protein catabolic rates were significantly increased in vastus lateralis white muscles, as well as two muscles that have a mixed fiber composition, diaphragm, and triceps. Protein catabolic rates were not increased in soleus muscle that predominately contained slow oxidative fibers in either group A or B. In group C rats there was no increase in catabolic rates in diaphragm or vastus lateralis white muscle. None of the muscles from group B had any impairment in protein synthesis. In diaphragms from group B animals, there was a selective reduction in the cross-sectional areas of fast glycolytic fibers (3725 ± 224 mm2 control vs. 2926 ± 208 mm2 experimental; P < 0.01). This study indicated that liver injury characterized by inflammation and hepatocyte necrosis, with or without cirrhosis, was associated with muscle atrophy that selectively affected fast glycolytic fibers. This muscle atrophy was caused by an increase in protein catabolism and was not the result of an inhibition of protein synthesis.

Hepatocyte membrane stabilization by prostaglandins E1 and E2: Favorable effects on rat liver injury

When prostaglandin (PG) E1 was continuously administered to rats from 24 hours before giving a dose of carbon tetrachloride, deranged serum glutamic pyruvic transaminase levels and prothrombin time were significantly reduced 12 hours after intoxication compared with controls. A similar effect of PGE1 was seen at 24 hours in d-galactosamine-intoxicated rats. Liver histology showed a comparable attenuation of injury in these rats. These results were consistent with reported effects of PGE2, suggesting that both prostaglandins may share a common pathway in protection against liver injury. When PGE1 or 16,16′-dimethyl PGE2 was added to the medium of primary cultured rat hepatocytes, lipid peroxidation-dependent killing of the cells by tert-butyl hydroperoxide was significantly attenuated without affecting the extent of malondialdehyde accumulation compared with controls. Both prostaglandins significantly reduced the extent of increased plasma membrane microviscosity of these cells assessed by 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene. PGE1 and PGE2 may possess cytoprotective effects on liver parenchymal cells through stabilization of membrane microviscosity, which may contribute to protection against liver injury.