Early morphological changes of porcine serum-induced hepatic fibrosis

When porcine serum is used to induce hepatic fibrosis in rats, linear septal fibrosis develops and outlines the periphery of Rappaport's functional liver acinus. A sequential morphological study was done to clarify the histogenesis of this hepatic fibrosis, especially in the early stages. Under light microscopic examination, the fibrotic septa developed as a thin fibrotic strand connecting terminal hepatic veins without any massive necrosis. Electron microscopic examination, however, revealed a thickening of the walls of the portal veins with narrowing lumen and damage to hepatocytes prior to the development of fibrosis. There was only mild inflammation and examination showed three types of mesenchymal cells; Ito cells, myofibroblasts, and fibroblasts. These changes suggested that this fibrosis is a result of hepatic damage, which in turn was possibly caused by disturbance of the portal vein.

Temporal relationship between hyperaldosteronism, sodium retention and ascites formation in rats with experimental cirrhosis

To investigate the role of aldosterone in sodium retention and ascites in cirrhosis, the urinary sodium excretion, sodium balance and urinary excretion of aldosterone-18-glucuronide (UAldV) were serially measured in 11 rats undergoing cirrhosis induction with carbon tetrachloride (CT) and phenobarbital (CT rats) and in 10 control rats which received phenobarbital. All CT rats developed ascites, seven within the ninth week after starting the program and four within the 10th week. One week before the onset of ascites, CT rats and control rats were different with respect to sodium excretion (1.41 +/- 0.15 vs. 1.82 +/- 0.1 mEq per day), sodium balance (0.57 +/- 0.12 vs. 0.20 +/- 0.09 mEq per day) and UAldV (67.8 +/- 9.5 vs. 25.7 +/- 1.7 ng per day). These differences were more pronounced within the week in which ascites was detected in CT rats. Before these 2 weeks, both groups did not differ with respect to these parameters. In the 132 urine samples obtained in CT rats, there was a correlation between sodium excretion and UAldV (r = -0.53; p less than 0.001). Twenty-one additional CT rats were divided into two groups. Eleven animals were given spironolactone (20 mg per day s.c. in olive oil) from the 6th week, and 10 only received olive oil. Thirteen weeks after starting the program, all rats not treated with spironolactone had sodium retention and ascites (in five rats, ascites appeared within the ninth week and in five within the tenth week); this occurred in only one animal treated with spironolactone.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged bile duct obstruction: a new experimental model for cirrhosis in the rat

Hepatic morphological abnormalities were examined in rats whose bile ducts had been either cannulated and then obstructed or irreversibly ligated for 5, 10, 15 and 28 days or longer. Throughout the experiment most of the morphological changes observed in the cannulated group were comparable to those in the ligated group. Portal inflammation and marginal bile duct proliferation were noted with the same frequency in both groups. Biliary obstruction for 15 days or more led to cirrhosis. After 28 days obstruction, five out of six cannulated rats and four out of six ligated animals respectively developed cirrhosis. The development of cirrhosis was progressive and associated with ascites. It is concluded that in the rat the morphological sequelae of long term cholestasis induced by either cannulation and obstruction or ligation of bile ducts are similar and are accompanied by cirrhosis. The advantages of this experimental model for the study of human cirrhosis are discussed.

Uninterrupted prolonged ethanol oxidation as a main pathogenetic factor of alcoholic liver damage: evidence from a new liquid diet animal model

Marked fatty infiltration and degenerative or mild inflammatory changes including eosinophilic cytoplasmic degeneration in centrilobular cells and focal inflammatory changes with cell necrosis were observed in livers of rats maintained for 12 weeks on a nutritionally adequate and balanced liquid ethanol diet. The animals continuously oxidized ethanol due to the supplementation of the diet with a low dose of 4-methylpyrazole (4-MP, an alcohol dehydrogenase inhibitor), that decreased ethanol elimination by about 20%. In other, equicalorically pair-fed groups of rats receiving (a) a similar ethanol-containing liquid diet without 4-MP or (b) a diet with 4-MP and 20% less ethanol, only a few minor changes were seen. The liver histology of rats pair-fed a control diet with a 4 times higher doses of 4-MP was completely normal. The results indicate that the prolonged imbalance of hepatic metabolism due to the uninterrupted oxidation of ethanol is a crucial factor in the development of alcoholic liver injury.

[Effect of choriogonine on the enzymatic activity of lysosomes in the cirrhotic liver in the rat]

Liver tissue cirrhosis, developed in rats after long-term administration of CCl4, led to distinct increase in activities of acid phosphatase, acid DNAase, cathepsin D, beta-galactosidase and beta-glucosidase. When the treatment with the hepatotropic toxins was stopped activity of lysosomal enzymes decreased slightly but was maintained at the high level. Within a day after a single administration of choriogonine distinct decrease as compared with the controls in activity of all the acid hydrolases studied was found. Within subsequent periods the lysosomal enzymes activity continued to decrease and within 2 months after the choriogonine treatment it was distinctly lower as compared with control animals.

Studies on the mechanism of alloxan-diabetes potentiation of carbon tetrachloride-induced liver necrosis

Carbon tetrachloride (CCl4)-induced liver necrosis in alloxan diabetic rats is markedly more intense than in controls as established by determination of isocitric dehydrogenase activity in plasma or by histological techniques. The covalent binding (CB) of CCl4 reactive metabolites to liver microsomal lipids is higher in alloxan diabetic rats than in controls. Cytochrome c reductase activity remains unchanged in alloxan diabetic rats. All the alterations described above observed in the diabetic animals are reverted by insulin administration. CCl4-induced lipid peroxidation of microsomal lipids, in contrast, is equally intense in controls than in alloxan diabetic animals and it is not modified by insulin treatment. Body temperature in alloxan diabetic animals treated with CCl4 is lower than in controls treated with the hepatotoxin. Results suggest that part of the enhanced necrogenic response of the liver observed in alloxan diabetic rats is due to increased CB to liver cell constituents but available evidence from the present and another work suggest that increased susceptibility of the liver from alloxan diabetic animals play a major role in the potentiation of CCl4 deleterious effects.

Experimental chronic non-suppurative destructive cholangitis in rabbits following immunization with bile duct antigen

Experimental chronic non-suppurative destructive cholangitis induced in rabbits following immunization with bile duct antigen. Histological changes similar to chronic non-suppurative destructive cholangitis were induced in rabbits by sensitization with antigen prepared from bovine gallbladder mucous membrane. The occurrence of these pathological changes was significantly higher in female animals than in males: 11 out of 14 female rabbits and 4 among 11 male rabbits exhibited histological changes. Immunoprecipitation using gel-diffusion and histological analysis by an immunofluorescence technique showed that this antigen was localized exclusively in the bile duct but not in either hepatocytes or other tissues. It is suggested that histological changes induced following immunization with bile duct antigen are specific immunological phenomena. This interesting experimental model may be helpful in explaining the pathogenesis of primary biliary cirrhosis.

Influence of dietary protein and vitamin B12 on the toxicity and carcinogenicity of aflatoxins in rat liver

The influence of dietary protein content and dietary vitamin B12 supplement on the hepatotoxicity and carcinogenicity of aflatoxin in rat liver was studied. In animals fed a low-protein diet, aflatoxin induced extensive toxic and carcinogenic effects. Cirrhosis was significantly prevented to a certain level by vitamin B12 administration, but the incidence of cholangiofibrosis and hyperplastic nodules was unchanged. No toxic effect was observed in animals receiving high-protein diet with no vitamin B12 supplement in this study (33 weeks). Only one rat bearing a hepatoma was observed in this group. However, hepatoma and hyperplastic nodules were found in the group receiving high-protein diet plus vitamin B12. Cholangiofibrosis and cirrhosis were not observed in the high-protein group regardless of vitamin B12 administration.

[Ultrastructural and functional features of the reversibility of sclerotic liver changes in rats treated with exogenous organ specific RNA]

Ultrastructural peculiarities of hepatocytes and Kupffer's cells in rats during the spontaneous reversibility of the experimental cirrhosis of the liver under the usual conditions and also under the influence of exogenous RNA, administered by different methods, were studied. The changes in cell ultrastructure proved to correlate with those of the quantitative indices of the protein synthesizing the liver function during the hepatic cirrhosis reversibility. A positive role of the RNA influence of short duration on the intracellular reparative hepatocytes regeneration, and a negative one in case of RNA influence of long duration was revealed. Participation in the resorption of collagen both of the parenchymal cells and of the stroma was shown.

Cirrhosis of choline deficiency in the Rhesus Monkey. Possible role of dietary cholesterol (38541)

One of five rhesus monkeys fed a diet deficient in choline and protein for 31 mo developed signs of cirrhosis at 26 mo. Five other monkeys were fed the same diet for 14 mo, at which time cholesterol comprising 2% of the diet was added. Three followed a sharp rise in hepatic lipids. One monkey developed marked hypercholesterolemia and showed signs of cirrhosis 2 mo after cholesterol supplementation. The findings indicate that the rhesus monkey is susceptible to choline-deficiency cirrhosis. They suggest that cholestrol supplementation accelerates this process.

Studies on the pathogenesis of experimental chronic active hepatitis in rabbits. I. Induction of the disease and protective effect of allogeneic liver specific proteins

By long-term immunization intraperitoneally over 143 weeks with human liver specific proteins (HLP) together with complete Freund's adjuvant a chronic active hepatitis (CAH) was produced in rabbits, and the protective effect of allogeneic liver specific proteins (RLP) against the development of liver lesions was tested. The animals (white New Zealands) were divided into 6 groups. Immunization with HLP caused in all animals the development of CAH or liver cirrhosis, depending on the antigen dose. An autoimmunity against liver antigens, induced by HLP, persisted by immunization with RLP. The combined application of HLP and RLP (native and aggregate free, respectively) caused the development of histologically demonstrable liver lesions in only 13% of the animals. Underlying the pathogenesis of the experimental CAH is, according to the existing results, a cellular cytotoxicity. This concept is supported by the protective effect of RLP on cellular immune reactions against RLP and the induction of liver lesions. The importance of an antibody mediated cellular cytotoxicity for the pathogenesis of the experimental CAH has to be clarified by further experiments.

Animal model: fatty liver and cirrhosis in lipotrope-deficient male rats

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[Blood and liver fat values in rats kept on a hyperlipid, hypoprotein, steatogenous diet, with or without choline]

Serum and liver tissue fatty acid and lipid fraction values were studied in rats kept for various periods on a hyperlipid, hypoprotein, steatogenous diet, with or witout choline. There was a general increase in liver fats due to an absolute increase in triglycerides, accompanied by changes in the fatty acid methyl ester composition, indicating the storage of lipids of lesser metabolic activity and more similar to those of peripheral fat (palmitic and oleic acid increments; decreases in myristic, stearic, linoleic and arachidonic acid values). These changes were partly reflected in the blood picture: little difference in lipid fraction ratios, coupled with fatty acid gas chromatograms similar to those observed for the liver. The omission of choline aggravated the alterations caused by the experimental diet.

[Electrophoretic behaviour of serum and liver proteins and of some isoenzymes in rats receiving a steatogenous, hyperlipidic, hypoprotein diet, with and without choline]

Albino rats were kept for long periods on a steatogenous, hypoproteic, hyperlipidic diets, either with or without choline. Serum protein and liver soluble protein and enzyme values showed changes that were only partly similar to those observed in human and experimental cirrhosis. The main features, in fact, were an absolute and percent decrease in albumins, an increase in serum alpha1-globulins and alpha proteins generally, and, more particularly, a constant fall in gamma-globulins and enzymes migrating to this site.