Dimethylnitrosamine Group Research Articles

The THE ROLE OF PLATELET RICH PLASMA AND QUERCETIN IN ALLEVIATING DIMETHYLNITROSAMINE-INDUCED ACUTE SPLEEN INJURY THROUGH REGULATING OXIDATIVE STRESS, INFLAMMATION AND APOPTOSIS

Objective: Excessive oxidative stress is implicated in spleen injury. Platelet-rich plasma (PRP) and quercetin (QUR) have been shown to protect cells against oxidative stress. This study was designed to investigate their effect on dimethyl nitrosamine (DMN) induced spleen injury in male rats.
 Methods: Forty male Wistar rats were divided into four groups; Group (1): Negative control group (Con), Group (2): DMN group, DMN was given intraperitonealy at a dose of 4 mg/kg b. wt/day for four weeks for sub-chronic injury of spleen tissue, Group (3): DMN+PRP, rats were injected intraperitonealy with DMN at a dose of 4 mg/kg b. wt/day for four weeks then treated i. v. by single dose 50 μL of PRP, then left for a period of four weeks without any treatments, Group(4): DMN+QUR, rats received intraperitonealy DMN at a dose of 4 mg/kg b. wt/day for four weeks, then treated with quercetin orally at a dose of 50 mg/kg b. wt. in aqueous suspension daily using an intragastric tube for four weeks.
 Results: DMN inoculation resulted in significant elevations of oxidative stress, as evidenced by the increased malondialdehyde, hydrogen peroxide and xanthine oxidase levels associated with a significant decrease in Superoxide dismutase and catalase activities in the spleen tissue as compared to the normal control group. Moreover, DMN caused an up-regulation in the values of the splenic C-reactive protein (CRP), interleuckin-6 (IL-6), nuclear factor kappa B (NF-κB), leukotriene-C4 (LT-C4), P53 and Fas levels with a significant decline in anti-apoptotic protein B-cell lymphoma 2 level as compared to the normal control group. PRP and QUR significantly attenuated the DMN-evoked spleen oxidative stress and modulated the activities of antioxidant enzymes as compared to DMN group. In addition, treatment of DMN group with PRP or QUR resulted in an improvement in CRP, IL-6, NF-κB, LT-C4, P53 and Fas levels as compared to DMN group. Caspase-3 expression was positive in DMN group while no difference was present in control, PRP and Quercetin groups. However, the VEGF immunopositive reaction was found in DMN, PRP and Quercetin groups compared to control group. Histopathological results showed degeneration, haemorrhage, inflammatory cells and necrotoic areas in splenic tissue from DMN group compared to the treated groups where signs of recovery were observed in the whole splenic tissue.
 Conclusion: These data suggest that PRP and QUR protect rat spleen from DMN-induced oxidative stress, probably via their antioxidant activity, anti-inflammatory and anti-apoptotic effects. So, PRP and QUR are promising pharmacological agents for preventing the potential spleen injury of DMN following occupational or environmental exposures.

Short-term detection of gastric genotoxicity using the DNA double-strand break marker γ-H2AX.

DNA damage caused by Helicobacter pylori infection and chronic inflammation or exposure to genotoxic agents is considered an important risk factor of gastric carcinogenesis. In this study, we have evaluated a short-term technique to detect DNA damage response to various chemical carcinogens; it involves visualization of Ser 139-phosphorylated histone H2AX (γ-H2AX) foci by immunohistochemistry and expression analysis of other genes by quantitative RT-PCR. Six-week-old male rats were intragastrically administered N-methyl-N-nitrosourea (MNU), 3,2’-dimethyl-4-aminobiphenyl (DMAB), dimethylnitrosamine (DMN), and 1,2- dimethylhydrazine (DMH) for 5 days/week for 4 weeks, using corn oil as a vehicle. Animals were sacrificed at day 28, and their stomachs were excised. γ-H2AX foci formation, indicating DNA double-strand breaks, was observed in the proliferative zone of both fundic and pyloric glands. The number of positive cells per gland was significantly high in pyloric glands in the MNU group and in fundic glands in the MNU and DMAB groups. A significant increase in p21waf1 mRNA level was observed in the DMN group compared with the control, which was in contrast to the decreasing tendency of the h2afx mRNA level in the MNU and DMN groups. Apoptotic cells positive for γ-H2AX pan or peripheral nuclear staining were observed on the surface layer of the fundic mucosa in the MNU group. The fundic pepsinogen a5 (pga5) mRNA level showed a significant decrease, indicating gland damage. The pyloric pepsinogen c mRNA level showed no change. In conclusion, γ-H2AX in combination with other gene expression analyses could be a useful biomarker in a short-term experiment on gastric chemical genotoxicity.

Antifibrotic effect of total flavonoids of Astmgali Radix on dimethylnitrosamine-induced liver cirrhosis in rats.

To study the effect of total flavonoids of Astmgali Radix (TFA) on liver cirrhosis induced with dimethylnitrosamine (DMN) in rats, and the effect on peroxisome proliferator-activated receptor γ (PPARγ), uncoupling protein 2 (UCP2) and farnesoid X receptor (FXR). Fifty-three Sprague-Dawley rats were randomly divided into a control group (10 rats) and a DMN group (43 rats). Rats in the DMN group were given DMN for 4 weeks and divided randomly into a model group (14 rats), a low-dosage TFA group (14 rats) and a high-dosage TFA group (15 rats) in the 3rd week. Rats were given TFA for 4 weeks at the dosage of 15 and 30 mg/kg in the low- and high-TFA groups, respectively. At the end of the experiment blood and liver samples were collected. Serum liver function and liver tissue hydroxyproline content were determined. hematoxylin-eosin (HE), Sirus red and immunohistochemical stainings of collagen I, smooth muscle actin (α-SMA) was conducted in paraffinembedded liver tissue slices. Real time polymerase chain reaction (PCR) was adopted to determine PPARγ, UCP2 and FXR mRNA levels. Western blot was adopted to determine protein levels of collagen I, α-SMA, PPARγ, UCP2 and FXR. Compared with the model group, TFA increased the ratio of liver/body weight (low-TFA group P<0.05, high-TFA group P<0.01), improved liver biochemical indices (P<0.01 for ALT, AST, GGT in both groups, P<0.05 for albumin and TBil in the high-TFA group) and reduced liver tissue hydroxproline content (P<0.01 in both groups) in treatment groups significantly. HE staining showed that TFA alleviated liver pathological changes markedly and Sirus red staining showed that TFA reduced collagen deposition, alleviated formation and extent of liver pseudolobule. Collagen I and α-SMA immunohistochemical staining showed that staining area and extent markedly decreased in TFA groups compared with the model group. TFA could increase PPARγ, it regulated target UCP2, and FXR levels significantly compared with the model group (in the low-TFA group all P<0.05, in the high group all P<0.01). TFA could improve liver function, alleviate liver pathological changes, and reduce collagen deposition and formation of liver pseudolobule in rats with liver cirrhosis. The antifibrotic effect of TFA was through regulating PPARγ signal pathway and the interaction with FXR.

Oxidative stress, histopathological and electron microscopic alterations induced by dimethylnitrosamine in renal male mice and the protective effect of α-lipoic acid.

Dimethylnitrosamine (DMN) is a waste product of several industrial processes. α-Lipoic acid (ALA) is a vitamin-like chemical also called as an antioxidant. Therefore, the study was designed to investigate the potential benefits of ALA in reducing the nephropathy of DMN in male mice. Animals were divided into 6 groups (n=8) and received their treatment for 4 weeks as follows: groups 1-4 served as control, ALA-treatment (16.12 mg/kg), DMN low dose treatment and DMN high dose treatment, respectively. Groups 5 and 6 received ALA before DMN low dose and DMN high dose, respectively. Superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase, total antioxidant capacity, nitric oxide, lipid peroxidation as well as the levels of uric acid and creatinine were determined. The histological and ultrastructure changes of renal tissue were also evaluated. Treatment of the DMN mice with ALA showed a reduction in the levels of kidney nitric oxide, lipid peroxidation, as well as creatinine and uric acid levels as compared with the DMN group. The results show that ALA plays an important role in quenching the free radicals resulting from the metabolism of DMN, thereby inhibiting lipid peroxidation and protecting membrane lipids from oxidative damage and, in turn, preventing oxidative stress and apoptosis. Histopathological and ultrastructure analysis of renal tissue confirmed the oxidative stress results occurred in DMN renal mice. Concomitant administration of ALA with DMN significantly decreased all the histopathological changes induced by DMN. The present study elucidated the therapeutic effects of ALA administered in combination with DMN to minimize its renal toxicity.

Huangqi decoction alleviates dimethylnitrosamine-induced liver fibrosis: An analysis of bile acids metabolic mechanism

Ethnopharmacological relevanceHuangqi Decoction (HQD), a classical traditional Chinese medicine (TCM) formula, is used to treating liver injury in China. The aim of the study is to investigate mechanisms of HQD against dimethylnitrosamine (DMN)-induced liver fibrosis underlying metabolic profiles of bile acids. Materials and methodsDMN-induced liver fibrosis rats were administrated HQD and its compounds, astragalosides (AS), glycyrrhizic acid (GA) and their combination. The anti-fibrosis effects were evaluated and targeted metabolomics by UPLC-MS was used to examine whether HQD had an influence on bile acid metabolism. The levels of mRNAs associated with bile acid metabolism were expressed by RT-PCR. Chenodeoxycholic acid (CDCA)-induced hepatic stellate cells (HSCs) proliferation and activation were examined using MTS assay and Western blot. ResultsHistopathological changes and serum liver function in HQD group had significant improvements (P<0.01). Concentrations of free bile acids and taurine conjugates were significantly increased in DMN group (P<0.05). HQD and its compounds restored the increased bile acids to normal levels, and HQD was more effected on parts of bile acids. Furthermore, the levels of mRNAs related bile acid synthesis and reabsorption such as CYP7A1, CYP8B1, CYP27A1, OATP2, OATP3, OATP4 and NTCP were significantly down-regulated in DMN group (P<0.05), mRNAs related excretion such as MRP3 and BESP were up-regulated (P<0.01), and CYP7A1, CYP8B1, OATP3, OATP4, NTCP and MRP3 restored to normal levels by HQD treatment. Moreover, CDCA-induced HSCs proliferation and activation were weaken by HQD (P<0.05) with down-regulated α-SMA, TGF-β1, p-Smad2 and p-Smad3 expressions. ConclusionsHQD alleviated DMN-induced liver fibrosis with a better effect than its compounds, which may be involved in the regulation of bile acid metabolism enzyme. Moreover, HQD may inhibit CDCA-induced HSCs proliferation and activation.

Reduction of Dimethylnitrosamine-Induced Liver Fibrosis by the Novel Gene Regulator PI Polyamide Targeting Transforming Growth Factor β1 Gene.

Pyrrole-imidazole (PI) polyamide is a novel gene regulating agent that competitively inhibits transcription factor binding to the promoter of the specific target gene. Liver fibrosis is an integral stage in the development of chronic liver disease, and transforming growth factor β (TGFβ) is known to play a central role in the progression of this entity. The aim of this study was to evaluate the effect of PI polyamide targeting TGFβ1 on rat liver fibrosis. PI polyamide was designed to inhibit activator protein 1 (AP-1) transcription factor binding to the TGFβ1 gene promoter. The effect of PI polyamide on hepatic stellate cells was evaluated by real time polymerase chain reaction (PCR) in RI-T cells. To determine the effect of PI polyamide in vivo, PI polyamide was intravenously administered at a dose of 3 mg/kg/week in dimethylnitrosamine (DMN)-induced rat model of liver fibrosis. Treatment of RI-T cells with 1.0 µM PI polyamide targeting TGFβ1 significantly inhibited TGFβ1 mRNA expression. Azan staining showed that DMN treatment significantly increased areas of fibrous materials compared with controls. PI polyamide targeting TGFβ1 significantly decreased the fibrous area compared with DMN group. mRNA expression levels of α-smooth muscle actin and matrix metalloproteinase-2 were significantly increased in DMN-treated group compared with control. Treatment with TGFβ1 PI polyamide significantly decreased mRNA expression of these genes compared with DMN group. The novel gene regulator PI polyamide targeting TGFβ1 may be a feasible therapeutic agent for the treatment of chronic liver disease.

Study of the therapeutic effects of Lactobacillus and α-lipoic acid against dimethylnitrosamine-induced liver fibrosis in rats

Abstract Lactobacillus (LB) and α-lipoic acid (ALA) were investigated to compare their protective effects against dimethylnitrosamine (DMN)-induced liver fibrosis in rats. Animals were either injected intraperitoneally with DMN to induce hepatic fibrosis, or were left untreated (negative control). For the DMN + LB and DMN + ALA treatment groups, at two weeks of DMN treatment LB or ALA was added to the feed and supplementation continued until the experimental endpoint at sixty days. At the study endpoint, expression of IL-1β, IL-6, IL-10, TNF-α, IFN-γ, TGF-β1, COL1-α1 genes and the concentration of glutathione and malondialdehyde were measured in liver tissues, while GOT, GPT, and ALP concentrations were measured in blood. Body weights remained higher in NC and DMN + LB groups compared to DMN and DMN + ALA groups, while activity of GOT and GPT in serum was lower in DMN + LB and DMN + ALA groups compared to the DMN group. Compared to other treatment groups, in the DMN group expression of both TGF-β1 and, COL1-α1 mRNAs and pro-inflammatory cytokines increased, while that of 1L-10 decreased. Furthermore, LB and ALA treatments increased antioxidant activity of glutathione and decreased malondialdehyde in comparison to the DMN group. Between LB and ALA treatments, glutathione concentration was higher in the DMN + LB group, while malondialdehyde was lower. Our results indicate that both LB and ALA exert hepatoprotective effects against DMN-induced liver fibrosis. Their beneficial effects may be partly associated with down-regulation of both TGF-β1 and COL1-α1 signaling, which may be accounted for reduction of increased oxidative stress and TNF-α production.

Alleviation of Dimethylnitrosamine-Induced Liver Injury and Fibrosis by Supplementation of Anabasis articulata Extract in Rats.

Anabasis articulata (Forssk) Moq. (Chenopodiaceae) is an herb, grows in Egypt, and used in folk medicine to treat diabetes, fever, and kidney infections. The protective and therapeutic effects of the ethanol extract of A. articulata aerial parts were evaluated against dimethylnitrosamine (DMN)-induced liver fibrosis, compared with the standard drug, silymarin. Hepatic hydroxyproline content, serum transforming growth factor-β1 (TGF-β1), interleukin 10 (IL-10) and fructosamine were measured as liver fibrosis markers. Hepatic malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), glutathione reductase (GR) and glutathione content (GSH) were measured as oxidant/antioxidant markers. Parallel histopathological investigations were also performed. Protective and therapeutic administration of A. articulata (100mg/kg daily for 4weeks), markedly prevented DMN-induced loss in body and liver weights. The extract significantly inhibited the elevation of hepatic hydroxyproline, NO and MDA (P<0.05), as well as serum fructosamine, and TGF-β1 (P<0.05) induced by DMN while it restored IL-10 to normal level in both protective and therapeutic groups. Furthermore, A. articulata prevented the depletion in CAT, GR, and GSH levels (P≤0.05). In addition, oral administration of A. articulata extract and silymarin to both protective and therapeutic groups reduced the increase in liver function enzyme activities; alanine and aspartate amintransferases, gamma-glutamyl transferase in addition to alkaline phosphatase, and caused significant increase in serum albumin concentration as compared to DMN group. These data corresponded closely with those obtained for the drug silymarin. Histopathological studies confirmed the biochemical data and revealed remarkable improvement in liver architecture. Thus, it could be concluded that, A. articulata extract exhibited in vivo hepatoprotective and therapeutic effects against DMN-induced liver injury and may act as a useful agent in controlling the progression of hepatic fibrosis through reduction of oxidative stress and improving liver function.

Effects of Chinese herbal medicine Yinchenhao Decoction on expressions of apoptosis-related genes in dimethylnitrosamine- or carbon tetrachloride-induced liver cirrhosis in rats

To investigate the different efficacy of Yinchenhao Decoction (YCHD), a compound traditional Chinese herbal medicine, for liver cirrhosis induced by dimethylnitrosamine (DMN) or carbon tetrachloride (CCl(4)) in rats. To induce liver fibrosis, 0.5% DMN solution (2mL/kg body weight, i.p.) was given three consecutive days a week to male Wistar rats for 4 weeks. Cirrhotic rats were randomly divided into DMN group, YCHD group, Xiaochaihu decoction group by the end of the fourth week to accomplish a 2-week recipe treatment course. In CCl(4)-induced liver fibrosis model, 50% CCl(4)-olive solution was injected subcutaneously to rats at a dose of 2 mL/kg body weight twice a week to duplicate rat cirrhosis model. After 8 weeks, rats were divided into CCl(4) group, CCl(4) plus YCHD group and Xiaochaihu decoction group. For the YCHD group, YCHD was administered intragastrically once a day for 4 weeks. For DMN or CCl(4) model, by the end of 6 or 12 weeks respectively, rats were sacrificed for sampling to detect liver function, hepatic histological changes, hydroxyproline (Hyp) content and apoptosis-related gene expressions. In DMN liver fibrosis model, hepatic fibrosis was obvious at week 2 and cirrhosis was evident at week 4 in DMN-treated rats. Compared to 6-week DMN group, hepatic pathological changes and liver function were improved significantly and content of Hyp decreased remarkably in YCHD group. In CCl(4)-induced liver fibrosis model, hepatic fibrosis was obvious at 8 weeks and cirrhosis was evident at 12 weeks in CCl(4)-treated rats. Compared to 12-week CCl(4) group, hepatic pathological changes and liver function were not obviously improvement in YCHD group. The results of gene chip showed that YCHD significantly decreased Fas, Bax and caspase-3 gene expressions, and increased Bcl-xL gene expression in the liver of DMN model. However, in the model induced by CCl(4), YCHD did not inhibit hepatocyte apoptosis induced by CCl(4), but increased tyrosine kinase receptor gene expression by 4.8 times. YCHD exerts more significant therapeutic effects on DMN-induced than CCl(4)-induced cirrhosis in rats in Hyp content and pathological change in liver tissue.

Preventive effect of Qianggan-Rongxian Decoction on rat liver fibrosis

To study the preventive effects of Qianggan-Rongxian Decoction on liver fibrosis induced by dimethylnitrosamine (DMN) in rats. Male Wistar rats were randomly divided into hepatic fibrosis model group, control group and 3 treatment groups (12 rats in each group). Except for the normal control group, all the rats received 1% DMN (10 muL/kg body weight, i.p), 3 times a week for 4 wk. The rats in the 3 treatment groups including a high-dose DMN group (10 mL/kg), a medium-dose DMN group (7 mL/kg), and a low-dose DMN group (4 mL/kg) were daily gavaged with Qianggan-Rongxian Decoction, and the rats in the model and normal control groups were given saline vehicle. Enzyme-linked immunosorbent assay (ELISA) was used to determine the changes in serum hyaluronic acid (HA), laminin (LN), and type IV collagen levels. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured using routine laboratory methods. Pathologic changes, particularly fibrosis, were examined by hematoxylin and eosin (HE) and Sirius red staining. Hepatic stellate cells (HSC) were examined by transmission electron microscopy. Compared with the model control group, the serum levels of HA, LN, type IV collagen, ALT and AST were decreased markedly in the other groups after treatment with Qianggan-Rongxian Decoction, especially in the medium-dose DMN group (P < 0.05). Moreover, the area-density percentage of collagen fibrosis was lower in the Qianggan-Rongxian Decoction treatment groups than in the model group, and a more significant drop was observed in the medium-dose DMN group (P < 0.05). Qianggan-Rongxian Decoction can inhibit hepatic fibrosis due to chronic liver injury, delay the development of cirrhosis, and notably ameliorate liver function. It may be used as a safe and effective thera-peutic drug for patients with fibrosis.

Effects of Yinchenhao Tang and related decoctions on DMN-induced cirrhosis/fibrosis in rats.

BackgroundChinese medicine decoctions such as Yinchenhao Tang (YCHT), Xiayuxue Tang (XYXT), Huangqi Tang (HQT), Yiguan Jian (YGJ) and Xiaochaihu Tang (XCHT)) were used to treat liver cirrhosis. The present study evaluates the effects of these decoctions on fibrosis in rats induced by dimethylnitrosamine (DMN).MethodsDMN solution (0.5%) was injected to rats for three consecutive days per week for four weeks. At the beginning of week 3, rats were randomly divided into 4-week DMN control group, YCHT, XYXT, HQT, YGJ, XCHT and vehicle groups. Each group was orally administered with specific decoctions daily for two weeks. Rats in the vehicle group were orally administered with only water.ResultsLiver fibrosis and cirrhosis were observed in weeks 2 and 4 in DMN-intoxicated rats. Compared with normal rats, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) activities and level of total bilirubin acid (TBA) in serum and content of Hydroxyproline (Hyp) in liver tissue of model group rats rose significantly. However, the albumin (Alb) level in serum decreased significantly. Compared with the 4-week DMN group, the pathological conditions and functions of the liver in the YCHT group improved significantly, and the content of Hyp decreased remarkably: only one rat in this group developed liver cirrhosis and the ratio of cirrhosis was only 8.3%. On the other hand, the other decoctions did not show remarkable effects. YCHT inhibited α-SMA activation, including its gene expression into mRNA and protein.ConclusionAmong the five Chinese medicine decoctions, YCHT exerted the most significant therapeutic effects on DMN-induced cirrhosis/fibrosis in rats.

Comparative study on organ-specificity of tumorigenicity, mutagenicity and cell proliferative activity induced by dimethylnitrosamine in Big Blue mice.

Recently, we have shown that dimethylnitrosamine (DMN) treatments increase lacI mutant frequency in the liver, kidney and lung but not in other organs, and also enhance cell proliferation only in the bronchial epithelia. In the present study, organ specificity of tumorigenicity induced by DMN was compared to those of lacI mutation and cell proliferation in Big Blue mice. Male 8-week-old Big Blue mice were treated with daily i.p. injections of 1 or 10 mg/kg DMN for 5 days, or a single i.p. injection of 5 or 10 mg/kg DMN. Except for the 10 mg/kg x 5 DMN group, all animals survived until 78 weeks after the first treatment of DMN. In the present study, the induction of cell proliferation in the bronchial epithelia was confirmed in a dose-dependent manner. At the termination of 78 weeks, it was histopathologically shown that the DMN-treated mice developed liver cell tumor in three out of seven (43%) of the 5 mg/kg group, renal tubule dysplasia in three out of seven (43%) of the 1 mg/kg x 5 group, and duodenal adenocarcinoma in one of seven (14%) of the 1 mg/kg x 5 group, although no neoplastic or preneoplastic lesions were found in the control mice. Because non-transgenic C57BL/6 mice are resistant to developing spontaneous liver cell and duodenal tumors, it was speculated that even these low doses of DMN could be sufficient to initiate target cells. Our results thus suggest that organ specificity of tumorigenicity by DMN is in favorable agreement with that of lacI mutation but not with possibly temporal cell proliferation induced by DMN.

Interferon gamma decreases hepatic stellate cell activation and extracellular matrix deposition in rat liver fibrosis.

Interferon gamma (IFN-gamma) inhibits in vitro the activation of hepatic stellate cells (HSC), the primary extracellular matrix-producing cells in liver fibrosis. This study was undertaken to determine in vivo the effect of IFN-gamma in the rat model of liver fibrosis induced by dimethylnitrosamine (DMN), where HSC activation represents an early response to cell injury. Rats were killed after 1 or 3 weeks of treatment with DMN, IFN-gamma, DMN + IFN-gamma, or saline. Immunohistochemistry was used to identify proliferating (desmin-positive/bromodeoxyuridine (BrdU)-positive cells) and activated (alpha-smooth-muscle actin [alpha-SMA]-positive cells) HSCs. Collagen deposition was determined colorimetrically and by morphometry. The parenchymal extension of desmin- and actin-positive cells and of fibrotic tissue was measured by point-counting technique and expressed as a percentage of area. Western blot was used to determine laminin and fibronectin accumulation. The levels of messenger RNA (mRNA) for procollagen type I, fibronectin, and laminin were evaluated by Northern blot. No differences were observed in rats treated with either saline or IFN-gamma alone. IFN-gamma reduced HSC activation induced by liver injury, as shown by the decreased number of proliferating HSC and the reduction of parenchymal area occupied by alpha-SMA-positive cells observed in DMN + IFN-gamma-treated animals compared with the DMN group. This was associated with reduced collagen, laminin, and fibronectin accumulation and lower levels of mRNA for procollagen type I, fibronectin, and laminin in the DMN + IFN-gamma group. Thus, this study indicates that IFN-gamma reduces extracellular matrix deposition in vivo by inhibition of HSC activation.

Interferon gamma decreases hepatic stellate cell activation and extracellular matrix deposition in rat liver fibrosis

Interferon gamma (IFN-gamma) inhibits in vitro the activation of hepatic stellate cells (HSC), the primary extracellular matrix-producing cells in liver fibrosis. This study was undertaken to determine in vivo the effect of IFN-gamma in the rat model of liver fibrosis induced by dimethylnitrosamine (DMN), where HSC activation represents an early response to cell injury. Rats were killed after 1 or 3 weeks of treatment with DMN, IFN-gamma, DMN + IFN-gamma, or saline. Immunohistochemistry was used to identify proliferating (desmin- positive/bromodeoxyuridine (BrdU)-positive cells) and activated (alpha- smooth-muscle actin [alpha-SMA]-positive cells) HSCs. Collagen deposition was determined colorimetrically and by morphometry. The parenchymal extension of desmin- and actin-positive cells and of fibrotic tissue was measured by point-counting technique and expressed as a percentage of area. Western blot was used to determine laminin and fibronectin accumulation. The levels of messenger RNA (mRNA) for procollagen type I, fibronectin, and laminin were evaluated by Northern blot. No differences were observed in rats treated with either saline or IFN-gamma alone. IFN-gamma reduced HSC activation induced by liver injury, as shown by the decreased number of proliferating HSC and the reduction of parenchymal area occupied by alpha-SMA-positive cells observed in DMN + IFN-gamma-treated animals compared with the DMN group. This was associated with reduced collagen, laminin, and fibronectin accumulation and lower levels of mRNA for procollagen type I, fibronectin, and laminin in the DMN + IFN-gamma group. Thus, this study indicates that IFN-gamma reduces extracellular matrix deposition in vivo by inhibition of HSC activation. (Hepatology 1996 May;23(5):1189-99)

Promoting role of Clonorchis sinensis infection on induction of cholangiocarcinoma during two-step carcinogenesis.

Chronic Clonorchis sinensis (CS) infection is etiologically related to cholangiocarcinoma (CHCA) in human and animals. This study was carried out to clarify the role of CS infection on dimethylnitrosamine (DMN)-induced cholangiocarcinogenesis. Fifteen hamsters were administered with 15 ppm DMN for 4 weeks and one week later, the hamsters were infected with 15 metacercariae of CS (DMN-->CS group). The other 15 hamsters were infected with CS and after 5 weeks they were treated with the drug, praziquantel. Again one week later, the hamsters were administered with DMN (CS-->DMN group). The other 15 hamsters were administered with DMN and CS simultaneously (CS+DMN group). Histopathological examination of the livers showed CHCA with papillary or adenomatous hyperplasia of bile ductules in 3 of 15 hamsters of DMN-->CS group and in 11 of 15 hamsters of DMN+CS group. These results suggest that CS infection to hamsters may have a promoting effect on the development of CHCA.

Intravascular coagulation in acute liver failure in rats and its treatment with antithrombin III.

Liver damage was induced in rats by injection of dimethylnitrosamine (DMN) or carbon tetrachloride (CCl4). Fibrin clots were observed in the hepatic sinusoids at 12 hours and soluble fibrin monomer complexes were markedly detected at 24 hours only in the rats given DMN. When antithrombin III concentrate was infused at 12 hours there was a dose dependent improvement of the values of serum total bilirubin, SGPT, prothrombin time, peripheral platelet count, and plasma fibrinogen and coagulation factor VIIIC and of the histological degree of liver injury at 24 hours in the DMN group. The CCl4-group showed no such improvement. Intravascular coagulation may complicate the course of certain types of acute liver injury and contribute to its aggravation in rats. Under such circumstances, treatment with antithrombin III concentrate would be beneficial.

Long-term experiment of maximal non-carcinogenic dose of dimethylnitrosamine for carcinogenesis in rats.

Studies were made on the maximal non-carcinogenic dose of dimethylnitrosamine (DMN) in rats. Groups of Wistar strain rats of both sexes, 6 weeks old, were given standard diet without DMN (group 1), or containing 0.1 ppm DMN (group 2), 1.0 ppm DMN (group 3), or 10 ppm DMN (group 4) for 96 weeks and then sacrificed for hematological, serum-biochemical, and histopathological examinations. After 96 weeks, the weights of the body and main organs in the different groups were not significantly different. The leucocyte count and blood urea-nitrogen (BUN) in group 4 were slightly increased, but other serum findings were not significantly different in different groups. Hepatocellular carcinomas were found in group 3 (1 male and 3 females), but not in group 2. Hemangioendotheliomas of the liver, adrenal adenomas, pituitary adenomas, interstitial cell tumors of the testis, ovarian tumors, and leukemia were also found. Pyelonephritis was found in both experimental and control animals, but no kidney tumors developed with these dose levels of DMN. These results show that on long-term oral administration to rats, 1.0 ppm DMN is the minimum carcinogenic dose, while a level of about 0.1 ppm DMN is non-carcinogenic.

The modification of the renal carcinogenicity of dimethylnitrosamine by actinomycin D and a protein deficient diet

The effect of a single treatment with 30 mg dimethylnitrosamine (DMN) and 6 mug actinomycin D (ACT), given at different time intervals (ACT application to DMN, 2 h before, simultaneously, 5, 9 or 48 h later), was tested in female Sprague-Dawley rats in relation to renal carcinogenesis; additionally, the animals were fed either a normal or a protein deficient diet. The ACT treatment did not significantly modify either the kidney tumour incidence or the survival time in the different groups fed a normal diet. Nevertheless, there are indications that additional ACT application may shorten the latency period for DMN induced renal neoplasms or, when administered 5 h later than DMN, a slightly decreased and delayed tumour induction can be assumed. In groups fed a protein deficient diet, a significantly higher percentage of kidney tumour bearing animals as well as a shortened latency period were found when compared with the DMN group on normal diet, but these differences were independent of the additional ACT treatment 9 h later than DMN and were due to the protein deprivation. Morphologically, the tumours were of epithelial and mesenchymal type with a clear preponderance of the former type. Biochemical and morphological aspects are discussed.