thromboxane-b2 and Liver-Diseases--Alcoholic

To investigate the effect of selective cyclooxygenase-2 (COX-2) inhibitor on alcohol-induced liver injury in rats.. 58 male Wistar rats were randomly divided into three groups: control group treated with dextrose and corn oil, model group with ethanol and corn oil, treatment group with corn oil and ethanol plus a selective COX-2 inhibitor celecoxib. All treatments were injected into stomach through intragastric tubes. Liver samples were analyzed for histopathology with light microscope (LM) and transmission electron microscope (TEM), and the expression of COX-2 with western blotting. Levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum, levels of 6-Keto-prostaglandin F1 alpha (6-k-PGF1a) and thromboxane B2 (TXB2) in liver, and activity of glutathione s-transferase (GST) both in liver tissue and in plasma were measured.. LM and TEM indicated hepatocytes were injured obviously in the model group and slightly in the treatment group. The levels of AST and ALT in serum, TXB2 in liver and the activity of GST in plasma increased significantly in the model group (t> or =2.294, P<0.05), but the activity of GST in liver decreased significantly (t=8.856, P<0.01) compared with those in the control group. To compare with the model group, the levels of AST and TXB2 decreased significantly (t=4.305, P<0.01; t=2.799, P<0.01), meanwhile the activity of GST increased significantly (t=10.134, P<0.01) in the treatment group. COX-2 expression in liver by western blotting increased significantly in the model group, compared with the control group (t=4.067, P<0.01) and the treatment group (t=2.251, P<0.05). Exceptionally, the level of 6-k-PGF1a decreased significantly (t=2.284, P<0.05) in the model group.. COX-2 has involved in the alcohol-induced liver injury, and its inhibitor can diminish alcohol-induced liver injury in rats through decreasing TXB2 level

Topics: Animals; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Disease Models, Animal; Ethanol; Isoenzymes; Liver Diseases, Alcoholic; Male; Prostaglandin-Endoperoxide Synthases; Protective Agents; Rats; Rats, Wistar; Thromboxane B2

Thromboxane levels correlate with severity of liver injury in rats given alcohol. The aim of this study was to evaluate the effect of thromboxane inhibitors on pathological changes in experimental alcoholic liver disease.. Male Wistar rats were given a liquid diet and ethanol intragastrically for 1 month. The thromboxane inhibitors tested were a thromboxane receptor antagonist (TXRA) and a thromboxane synthase inhibitor (TXSI). Pathological changes, liver and plasma thromboxane levels, 6-ketoprostaglandin F1 alpha levels, lipid peroxidation, and messenger RNA levels for tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF) beta were evaluated.. Treatment with thromboxane inhibitors prevented necrosis and inflammation. In the TXSI-treated group, fatty liver was also decreased. Ethanol administration led to a 3-4-fold increase in liver thromboxane levels; a reduction in thromboxane levels and lipid peroxidation was seen in the TXSI group. In all treatment groups, TNF-alpha and TGF-beta messenger RNA levels were decreased.. The prevention of necroinflammatory changes in thromboxane-treated groups is related to a decrease in TNF-alpha levels. Inhibition of TGF-beta expression may also prevent fibrosis in ethanol-treated rats.

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Fatty Liver, Alcoholic; Liver Diseases, Alcoholic; Male; Oxazoles; Rats; Rats, Wistar; Thromboxane A2; Thromboxane B2; Transforming Growth Factor alpha; Transforming Growth Factor beta

Inflammatory stimuli and lipid peroxidation up-regulate cyclooxygenase (COX)-2. This study evaluated the relationship between inflammatory mediators, COX expression, and pathological changes in experimental alcoholic liver disease.. Rats (5 per group) were fed ethanol and a diet containing saturated fat, corn oil, or fish oil by intragastric infusion. Dextrose isocalorically replaced ethanol in controls. In the first set of experiments, whole livers were analyzed. In the second set of experiments, Kupffer cells, endothelial cells, and hepatocytes were isolated from rats in each group. Pathological analyses and measurements of lipid peroxidation, tumor necrosis factor (TNF)-alpha, COX-1 and COX-2 messenger RNA (mRNA), endotoxin, and liver and plasma thromboxane were performed.. Increased expression of COX-2 mRNA was detected in the livers of rats showing necroinflammatory changes. The Kupffer cell was the cell primarily responsible for the increase in COX-2 mRNA level. Increased expression of COX-2 was associated with increased levels of endotoxin, TNF-alpha mRNA, lipid peroxidation, and synthesis of thromboxane. COX-1 mRNA was decreased in Kupffer cells in rats with the most severe liver injury.. Up-regulation of COX-2 in alcoholic liver injury occurred in the presence of proinflammatory stimuli and resulted in increased synthesis of inflammatory and vasoactive eicosanoids. Down-regulation of COX-1 may result in decreased synthesis of cytoprotective eicosanoids and additionally exacerbate liver injury.

Topics: Animals; Cyclooxygenase 2; Endotoxemia; Gene Expression Regulation, Enzymologic; Isoenzymes; Kupffer Cells; Lipid Peroxidation; Liver Diseases, Alcoholic; Male; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; RNA, Messenger; Thromboxane B2; Tumor Necrosis Factor-alpha

Based on studies that show a role for the low-density lipoprotein (LDL)-receptor in arachidonic acid delivery and eicosanoid synthesis in macrophages, the present study investigated the effect of cholesterol supplementation on pathological changes and thromboxane (TX) synthesis in alcoholic liver injury. Male Wistar rats were intragastrically fed ethanol with either corn oil or fish oil for 1 month. Control rats received isocaloric amounts of dextrose instead of ethanol. An additional group of rats fed either ethanol or dextrose with fish oil or corn oil were supplemented with 1% cholesterol. At the time of killing, all rats had the following evaluated: liver histopathology, lipid peroxidation, liver and plasma thromboxane levels, plasma endotoxin and messenger RNA (mRNA) levels of LDL-receptor, tumor necrosis factor alpha (TNF-alpha), cyclooxygenase (Cox)-1 and -2, and transforming growth factor beta (TGF-beta). Rats fed ethanol with either fish oil or corn oil developed fatty liver, necrosis, inflammation, and central vein collagen deposition. Cholesterol supplementation enhanced the degree of fibrosis but prevented necrosis and inflammation. These alterations in pathological changes by cholesterol were accompanied by absent TNF-alpha and Cox-2 mRNAs, decreased thromboxane levels, decreased lipid peroxidation, and increased TGF-beta mRNA. Cholesterol enrichment of the diet thus decreases proinflammatory components, but enhances fibrosis in ethanol-fed rats.

Topics: Animals; Cholesterol; Inflammation; Lipids; Liver; Liver Cirrhosis; Liver Diseases, Alcoholic; Male; Necrosis; Rats; Rats, Wistar; RNA, Messenger; Thromboxane B2; Transforming Growth Factor beta

We have previously shown that hepatic thromboxane production is increased in experimental alcoholic liver disease. The present study was designed to investigate the cell type in liver responsible for increased thromboxane synthesis and the role of the thromboxane receptor system in the pathogenesis of liver injury. Male Wistar rats were divided into four groups and fed a liquid diet with dextrose or ethanol for 2, 4 and 8 weeks. Medium chain triglycerides or corn oil provided the dietary fatty acids. Kupffer cells, endothelial cells and hepatocytes were isolated from rats fed the different diets for 4 weeks. Liver histopathology, thromboxane synthase mRNA and protein, thromboxane levels and thromboxane receptor mRNA were evaluated in each group. In rats fed corn oil and ethanol, an increase in thromboxane synthase and liver levels of thromboxane metabolites were significantly higher than in the corn oil-dextrose-fed group and were correlated with the presence of pathological changes in the liver. Kupffer cells showed increased expression of thromboxane synthase. In rats fed medium chain triglycerides and ethanol, the levels of thromboxane synthase mRNA and protein were significantly lower than in the corn oil-ethanol-fed groups (P < .01) and liver injury was absent. However, the levels of thromboxane synthase mRNA, protein and thromboxane were significantly higher in the medium chain triglyceride-ethanol-fed rats than in the respective dextrose-fed controls. Among the different cell types, thromboxane A2-receptor mRNA levels were highest in the Kupffer cells in corn oil-ethanol-fed rats. The increase in thromboxane synthase in Kupffer cells together with an increase in thromboxane receptor levels suggests than thromboxanes may contribute to liver injury in ethanol-fed rats.

Topics: Animals; Immunohistochemistry; Liver; Liver Diseases, Alcoholic; Male; Rats; Rats, Wistar; Receptors, Thromboxane; RNA, Messenger; Thromboxane B2; Thromboxane-A Synthase

Cytochrome P450 induction is believed to be important in the pathogenesis of alcoholic hepatic disease. Because cimetidine is a general inhibitor of cytochrome P450 enzymes, it was hypothesized that it could be useful in preventing alcoholic hepatic injury. An intragastric feeding model was used these studies. Experimental animals were divided into groups of four to five rats/group and fed the following diets: corn oil+dextrose, corn oil+ethanol (CE) and corn oil+ethanol+cimetidine (250 mg kg-1 day-1) (CEC). The rats in each group were sacrificed at the following time intervals: 2 weeks, 1 month and 2 months. For each animal, the severity of the pathologic findings and relative protein levels of cytochromes P450 2E1, 2B and 4A were measured. In addition, plasma levels of thromboxane B2, 6-ketoprostaglandin F1 alpha and 8-isoprostane were also measured. The most significant finding was that cimetidine completely prevented alcoholic hepatic injury in this model system. The pathologic scores (an indication of the severity of injury) were significantly lower in the CEC groups compared with the CE group. There was however, no significant difference in cytochrome P450 2E1, 2B or 4A protein levels between CE and CEC groups. Thromboxane B2 and 8-isoprostane levels were significantly lower and 6-ketoprostaglandin F1 alpha, significantly higher in the CEC group than in the CE group. These results indicate that possible mechanisms involved in the protective action of cimetidine include inhibition of thromboxane production and lipid peroxidation.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Arachidonic Acid; Arachidonic Acids; Cimetidine; Cytochrome P-450 Enzyme System; Dinoprost; Disease Models, Animal; Endotoxins; F2-Isoprostanes; Lipid Peroxidation; Liver Diseases, Alcoholic; Male; Rats; Rats, Wistar; Thromboxane B2

The purpose of our study is to determine if a relationship exists between the severity of injury in experimental alcoholic liver disease and plasma levels of endotoxin, prostaglandin E2, leukotriene B4, and thromboxane B2. Four groups of animals (n = 4 to 8 in each group) were fed a liquid diet with corn oil (25% of calories) and ethanol over various time periods: 1 week, 2 weeks, 1 month, and 2 months. At sacrifice, liver pathology scores and plasma levels of the above were determined. Plasma levels of endotoxin were already increased after 1 week (26.6 +/- 18.6 pg/ml) and continued to increase over time, with the highest levels at 2 months (69.5 +/- 24.5 pg/ml). A strong positive correlation (r = 0.84, P < 0.001) was seen between plasma endotoxin levels and severity of liver injury. The pathology score also correlated positively with leukotriene B4 (r = 0.47, P < 0.05) and thromboxane B2 (0.66, P < 0.01). A negative correlation was obtained with prostaglandin E2 levels (r = -0.44, P < 0.05). A positive correlation was also seen between endotoxin levels and leukotriene B4 (r = 0.57, P < 0.02) and thromboxane B2 (0.64, P < 0.01); a negative correlation was obtained with prostaglandin E2 levels (r = -0.55, P < 0.02). Each metabolite was also correlated with each of the features of alcoholic liver injury, i.e., fatty liver, necrosis, and inflammation. With prostaglandin E2, the most marked decrease was seen in association with severe fatty liver (3 to 4+). Thromboxane B2 correlated best with presence of inflammation and necrosis. Our study shows the importance of endotoxin in the pathogenesis of experimental alcoholic liver disease and suggests that endotoxin modulates production of eicosanoids that contribute to the severity of liver injury.

Topics: Animals; Dinoprostone; Eicosanoids; Endotoxins; Leukotriene B4; Liver; Liver Diseases, Alcoholic; Male; Rats; Rats, Wistar; Thromboxane B2

The present study evaluated the possible protective effect of ((2E)-3-[5-(2,3 dimethoxy-6-methyl-1,4-benzoquinoyl)]-2-nonyl-2-propanoic acid) (E3330), a newly synthesized hepatoprotective-quinone derivative, on experimental alcoholic liver injury. The intragastric feeding rat model for alcoholic liver disease was used. Eight sets of experiments were performed in which animals fed either corn oil and ethanol or corn oil, ethanol and E3330 were sacrificed at intervals of 1 week, 2 weeks, 1 month and 2 months. Nonparenchymal cell supernatant (NPCS) and plasma measurements of tumor necrosis factor, prostaglandin E2, leukotriene B4 and thromboxane B2 were evaluated in relation to the development of pathologic liver injury. Oral treatment with E3330 reduced the severity of liver injury; this was accompanied by a reduction in thromboxane B2 and leukotriene B4 levels in both NPCS and plasma and a reduction in tumor necrosis factor levels in NPCS. The difference in pathologic severity between drug- and nondrug-treated groups correlated well with the changes in the NPCS and plasma thromboxane B2/prostaglandin E2 ratio. These findings suggest that E3330 has multiple actions, such as inhibition of thromboxane, leukotriene and tumor necrosis factor generation, which contribute to its protective effect in alcoholic liver injury.

Topics: Animals; Benzoquinones; Dinoprostone; Leukotriene B4; Liver; Liver Diseases, Alcoholic; Male; Propionates; Rats; Rats, Wistar; Thromboxane B2; Tumor Necrosis Factor-alpha

Recently, hepatic microcirculation has been focused on as an important pathogenic factor in progression of alcoholic liver disease (ALD). Therefore, blood levels of several prostaglandins, which are associated with organ microcirculation, were determined in various liver diseases, including ALD. Blood thromboxane B2 (TXB2) level was significantly increased in ALD, when compared to other types of liver diseases, whereas both 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) and prostaglandin E were not changed. These consequences resulted in the imbalance of 6-keto PGF1 alpha to TXB2, which might promote platelet aggregation and blood vessel contraction. Indeed, the increase of beta-thromboglobulin and platelet factor 4 in blood was observed in ALD. Furthermore, in ALD, the rate of arachidonate-induced platelet aggregation was prominently enhanced, and malondialdehyde production in platelet, which was well correlated with blood TXB2 levels, significantly increased. Thus, the present study may indicate that, in ALD, hyper-aggregability of platelet is produced, because of the derangement of prostaglandin metabolism and platelet dysfunction.

Topics: Adult; Alcoholism; beta-Thromboglobulin; Blood Platelets; Humans; Liver Diseases, Alcoholic; Malondialdehyde; Middle Aged; Platelet Aggregation; Platelet Factor 4; Prostaglandins; Thromboxane B2

Collagen-, arachidonate- and ADP-stimulated platelet thromboxane B2 (TXB2) formation was studied in platelet-rich plasma (PRP) of 14 alcoholics, 7 of whom had a biopsy-verified alcoholic fatty liver. On admission for detoxication, the alcoholics showed decreased platelet count and aggregability (p less than 0.001) as compared to nonalcoholic healthy controls. Platelet TXB2 formation was decreased (p less than 0.01), if PRP was stimulated by arachidonate, but not if it was stimulated by ADP or collagen. In contrast, 9-14 days after ethanol withdrawal platelet TXB2 formation had increased to markedly higher levels than those seen in nonalcoholic controls (p less than 0.01), if PRP was stimulated by ADP, but not if it was stimulated by arachidonate or collagen. Skin bleeding time was found to be prolonged (p less than 0.05) on admission in alcoholics having fatty liver, but it normalized within 2 weeks after ethanol withdrawal. We conclude that the effect of ethanol withdrawal in alcoholics on platelet TXB2 formation is influenced by platelet count, aggregability and the agonist used to induce platelet aggregation.

Topics: Adenosine Diphosphate; Adult; Alcoholism; Arachidonic Acid; Arachidonic Acids; Bleeding Time; Blood Platelets; Collagen; Ethanol; Female; Fibrinogen; Humans; Liver Diseases, Alcoholic; Male; Middle Aged; Platelet Aggregation; Platelet Count; Serum Albumin; Substance Withdrawal Syndrome; Thromboxane B2

In experimental animals endotoxin administration causes increased levels of thromboxane B2 and prostaglandins. Liver cirrhosis is often complicated by endotoxemia. In sixteen patients with alcoholic liver cirrhosis, we measured plasma thromboxane B2 levels. In twelve patients we found on one or more occasions raised plasma thromboxane B2 levels. Raised plasma thromboxane B2 levels were associated with significantly higher serum levels of urea, alkaline phosphatase, gamma glutamyl transpeptidase and lower antiplasmin and antithrombin III levels. It is possible that some of the complications in patients with alcoholic liver cirrhosis are mediated by thromboxanes.

Topics: Adult; Aged; Female; Humans; Liver Cirrhosis, Alcoholic; Liver Diseases, Alcoholic; Male; Middle Aged; Platelet Count; Thromboxane B2; Thromboxanes