二甲基亚硝胺肝纤维化过程中金属蛋白酶组织抑制因子1基因表达的动态变化

目的 观察肝纤维化过程中TIMP -1基因表达的动态变化 ,探讨肝纤维化的发生发展机理 ,以及中药复方 86 1的抗纤维化机制。方法 10 0只Wistar大鼠随机分为正常对照组、模型组和复方 86 1预防组。模型组用二甲基亚硝胺 (DMN)腹腔内注射诱导大鼠发生肝纤维化 ,共计 6周 ,第 1周注射 3次 ,其它周均注射 2次 ,观察 8周 ;复方 86 1预防组大鼠则在用DMN腹腔注射的同时 ,每天接受中药灌胃 1次 ,直至实验结束 ;正常对照组以生理盐水代替DMN腹腔内注射。分别于第 1、 4、 10、 17、 2 8、 42、 5 6天分批处死动物 ,取出肝脏 ,以半定量RT -PCR法检测肝组织中TIMP -1mRNA。结果 从动态发展来看 ,正常对照组大鼠肝组织TIMP -1mRNA的表达水平基本稳定不变 ;模型组大鼠肝组织TIMP -1mRNA的表达从第 4天开始升高 ,10天后一直维持高水平表达直至动物实验结束 ;复方86 1预防组TIMP -1mRNA的表达变化不大。从组间比较来看 ,模型组肝组织TIMP -1mRNA的表达水平从第 4天开始即比正常对照组明显增高 ,此后升高更显著直至实验结束 ;86 1预防组从第 10天开始比正常对照组有所增高 ,但比模型组明显低 ,从 2 8天开始以后则比模型组降低越发显著。结论 TIMP -1的表达在肝纤维化的发展过程中逐渐增高。它能抑制纤维胶原降解 ,因?

Iron deposition and fat accumulation in dimethylnitrosamine-induced liver fibrosis in rat

AIM： To investigate if iron deposition and fat accumulation in the liver play a pathogenetic role in dimethylnitrosamine （DMN）-induced liver fibrosis in rat.METHODS： Thirty rats were treated with DMN at does consecutive days of 10 μL/kg daily, i.p., for 3 consecutive day each week for 4 wk. Rats （n = 30） were sacrificed on the first day （model group A） and 21st d （model group B） after cessation of DMN injection. The control group （n = 10） received an equivalent amount of saline. Liver tissues were stained with hematoxylin ＆ eosin （HE） and Masson and Prussian blue assay and oberserved under electron microscopy. Serum alanine aminotransferase （ALT）and liver tissue hydroxyproline （Hyp） content were tested.RESULTS： The liver fibrosis did not automaticallyreverse, which was similar to previous reports, the perilobular deposition of iron accompanied with collagen showed marked characteristics at both the first and 21st d after cessation of DMN injection. However, fat accumulation in hepatocytes occurred only at the 21^st d after cessation of DMN injection.CONCLUSION： Iron deposition and fat accumulation may play important roles in pathological changes in DMN-induced rat liver fibrosis. The detailed mechanisms of these characteristics need further research.

An herbal formula,CGX,exerts hepatotherapeutic effects on dimethylnitrosamine-induced chronic liver injury model in rats

AIM： To evaluate the therapeutic effect of Chunggan extract （CGX）, a modified traditional Chinese hepatotherapeutic herbal, on the dimethylnitrosamine （DMN）-induced chronic liver injury model in rats. METHODS： Liver injuries were induced in Wistar rats by injection of DMN （ip, 10 mg/mL per kg） for 3 consecutive days per week for 4 wk. The rats were administered with CGX Coo, 100 or 200 mg/kg per day） or distilled water as a control daily for 4 wk starting from the 15^th d of the DMN treatment. Biochemical parameters （serum albumin, bilirubin, ALP, AST and ALT）, lipid peroxides, hydroxyproline, as well as histological changes in liver tissues were analyzed. In addition, gene expression of TNF-α, TGF-β, TIMP-1, TIMP-2, PDGF-β, and MMP-2, all of which are known to be associated with liver fibrosis, were analyzed using real-time PCR. RESULTS： CGX administration restored the spleen weight to normal alter having been increased by DMN treatment. Biochemical analysis of the serum demonstrated that CGX significantly decreased the serum level of ALP （P 〈 0.05）, ALT （P 〈 0.02）, and AST （P 〈 0.02） that had been elevated by DMN treatment. CGX administration moderately lowered lipid peroxide production and markedly lowered hydroxyproline generation caused by DMN treatment in accordance with histopathological examination. DMN treatment induced a highly upregulated expression of TNF-α, TGF-β,TIMP-1, TIMP-2, PDGF-β, and MMP-2. Of these, the gene expression encoding PDGF-β and MMP-2 was still further enhanced 2 wk after secession of the 4-wk DMN treatment, and was remarkably ameliorated by CGX administration. CONCLUSION： CGX exhibits hepatotherapeutic properties against chronic hepatocellular destruction and consequential liver fibrosis.

Antifi brotic effects of green tea on in vitro and in vivo models of liver fibrosis

AIM: To examine the protective effect of green tea extract (GT) on hepatic fi brosis in vitro and in vivo in dimethylnitrosamine (DMN)-induced rats.METHODS: HSC-T6, a rat hepatic stellate cell line, was used as an in vitro assay system. Cell proliferation, collagen content, and type 1 collagen expression were examined in activated HSC-T6 cells. Collagen was determined by estimating the hydroxyproline content. In rats with DMN-induced hepatic fi brosis, serum aspartate aminotransferase and alanine aminotransferase concentrations, liver hydroxyproline and lipid peroxides were determined. Pathologic changes were examined by hematoxylin & eosin staining.RESULTS: GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fi brosis. These results were confi rmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.CONCLUSION: This study demonstrates that greentea administration can effectively improve liver fibrosis caused by DMN, and may be used as a therapeutic option and preventive measure against hepatic f ibrosis.

Nitrosamine and related food intake and gastric and oesophageal cancer risk: A systematic review of the epidemiological evidence

AIM： To study the association between nitrite and nitrosamine intake and gastric cancer （GC）, between meat and processed meat intake, GC and oesophageal cancer （OC）, and between preserved fish, vegetable and smoked food intake and GC. METHODS： In this article we reviewed all the published cohort and case-control studies from 1985-2005, and analyzed the relationship between nitrosamine and nitrite intake and the most important related food intake （meat and processed meat, preserved vegetables and fish, smoked foods and beer drinking） and GC or OC risk. Sixty-one studies, 11 cohorts and 50 case-control studies were included. RESULTS： Evidence from case-control studies supported an association between nitrite and nitrosamine intake with GC but evidence was insufficient in relation to OC. A high proportion of case-control studies found a positive association with meat intake for both tumours （11 of 16 studies on GC and 11 of 18 studies on OC）. A relatively large number of case-control studies showed quite consistent results supporting a positive association between processed meat intake and GC and OC risk （10 of 14 studies on GC and 8 of 9 studies on OC）. Almost all the case-control studies found a positive and significant association between preserved fish, vegetable and smoked food intake and GC. The evidence regarding OC was more limited. Overall the evidence from cohort studies was insufficient or more inconsistent than that from case-control studies.CONCLUSION： The available evidence supports a positive association between nitrite and nitrosamine intake and GC, between meat and processed meat intake and GC and OC, and between preserved fish, vegetable and smoked food intake and GC, but is not conclusive.

Upregulation of TNF-α mRNA in hepatic fibrosis rats induced by dimethylnitrosamine

Objective:To observe the expression level of TNF-α mRNA in rats with hepatic fibrosis induced by dimethylnitrosamine (DMN) and to explore its relationship with collagen metabolism and its diagnostic value for hepatic fibrosis.Methods: Twenty-five male Wistar rats were randomly divided into normal control group (n=10) and model group (n=15). Model rats were induced by DMN for 4 weeks and at final stage were executed. TNF-α mRNA were detected by RT-PCR and the inflammatory necrosis and collagen deposition in hepatic tissue were observed by HE stain and Sirius red stain. The liver functions were determined by automatic biochemical analytic device. The serum marks of liver fibrosis, such as HA, LN and Ⅳ-C were measured with ELISA and RIA. Results: In this study, the rat model of liver fibrosis induced by DMN was successfully constructed. RT-PCR reveals that TNF-α mRNA expression in control group is lower than that of model group. The liver functions of model group were impaired compared with those of the control group (P<0.01). Semi-quantitive analysis revealed that TNF-α/β-actin of normal rats was 0.39±0.12, while 0.93±0.05 of model rats. The concentration of HA (434.44±98.81 vs 252.9±26.59 ng/ml, P<0.01), LN (70.67±6.32 vs 37.90±5.97 ng/ml, P<0.01) and Ⅳ-C (79.39±10.52 vs 21.40±4.17 ng/ml, P<0.01) were significantly increased in the model group as well. Changes of the indexes were similar to the pathological damage of the liver. Conclusion: The results suggested that activation of TNF-α in liver tissues may be the common pathogenic mechanism of liver fibrosis. TNF-α may be a useful index for the diagnosis of hepatic fibrosis which worthies further investigation.

Effects of Salvia miltiorrhiza injectional powder on the development of liver fibrosis initiated by dimethylnitrosamine in rats

Salvia miltiorrhiza （Sm） is a traditional herbal medicine with multiple effects on various diseases. Its water-soluble parts have been used to produce injectional powder. In this study, liver fibrosis rats were induced by intraperitoneal injection of dimethylnitrosarnine for 3 consecutive days per week for 4 weeks. After 2 weeks, rats in the positive drug group were subcutaneously injected with 8×10^5 IU/kg IFNα2b, while the Sm treatment groups were intraperitoneally injected with 50, 100 and 200 mg/kg solution of Sm injectional powder, respectively, for 6 days per week for 4 weeks. The results showed that either IFNα2b or the Sm injectional powder significantly increased the body weight and liver to spleen ratio, and three doses of the powder brought down the spleen index. Serum analysis showed that both IFNα2b and the Sm powder reduced levels of alanine transaminase and total bilirubin, while only 100 and 200 mg/kg of the Sm powder ameliorated aspartate transaminase and albumin levels. In the collagen examination, reduced hyaluronic acid and procollagen type III levels, less fibrous hyperplasia and collagen deposits, and improved hepatocyte states were clearly observed in rats treated with either IFNα2b or Sm injectional powder. In addition, the mechanism of action of the Sm powder was also studied. Immunohistochemical staining showed that IFNα2b and Sm injectional powder significantly down-regulated the expression of transforming growth factor-β1 （TGF-β1） and platelet derived growth factor （PDGF）. In conclusion, Sm injectional powder has protective effects on dimethylnitrosamine-initiated liver fibrosis in rats, and the mechanism may include the down-regulation of TGF-β1 and PDGF.