Hepatoprotective activity of bacoside A against <Emphasis Type="Italic">N</Emphasis>-nitrosodiethylamine-induced liver toxicity in adult rats

N-Nitrosodiethylamine (DEN) is a notorious carcinogen, present in many environmental factors. DEN induces oxidative stress and cellular injury due to enhanced generation of reactive oxygen species; free radical scavengers protect the membranes from DEN-induced damage. The present study was designed to evaluate the protective effect of bacoside A (the active principle isolated from Bacopa monniera Linn.) on carcinogen-induced damage in rat liver. Adult male albino rats were pretreated with 15 mg/kg body weight/day of bacoside A orally (for 14 days) and then intoxicated with single necrogenic dose of N-nitrosodiethylamine (200 mg/kg bodyweight, intraperitonially) and maintained for 7 days. The liver weight, lipid peroxidation (LPO), and activity of serum marker enzymes (aspartate transaminases, alanine transaminases, lactate dehydrogenase, alkaline phosphatase, and γ-glutamyl transpeptidase) were markedly increased in carcinogen-administered rats, whereas the activities of marker enzymes were near normal in bacoside A-pretreated rats. Activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutatione-S-transferase, and reduced glutathione) in liver also decreased in carcinogen-administered rats, which were significantly elevated in bacoside A-pretreated rats. It is concluded that pretreatment of bacoside A prevents the elevation of LPO and activity of serum marker enzymes and maintains the antioxidant system and thus protects the rats from DEN-induced hepatotoxicity.     

Potential preventive effect of carvacrol against diethylnitrosamine-induced hepatocellular carcinoma in rats

Antioxidants are one of the key players in tumorigenesis, several natural and synthetic antioxidants were shown to have anticancer effects. The aim of the present study is to divulge the chemopreventive nature of carvacrol during diethylnitrosamine (DEN)-induced liver cancer in male wistar albino rats. Administration of DEN to rats resulted in increased relative liver weight and serum marker enzymes aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma glutamyl transpeptidase (γGT). The levels of lipid peroxides elevated (in both serum and tissue) with subsequent decrease in the final body weight and tissue antioxidants like superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione reductase (GR). Carvacrol supplementation (15 mg/kg body weight) significantly attenuated these alterations, thereby showing potent anticancer effect in liver cancer. Histological observations and transmission electron microscopy studies were also carried out, which added supports to the chemopreventive action of the carvacrol against DEN-induction during liver cancer progression. These findings suggest that carvacrol prevents lipid peroxidation, hepatic cell damage, and protects the antioxidant system in DEN-induced hepatocellular carcinogenesis.     

Potential chemoprevention of diethylnitrosamine-initiated and 2-acetylaminofluorene-promoted hepatocarcinogenesis by zerumbone from the rhizomes of the subtropical ginger (Zingiber zerumbet)

Zerumbone (ZER), a monosesquiterpene found in the subtropical ginger (Zingiber zerumbet Smith), possesses antiproliferative properties to several cancer cells lines, including the cervical, skin and colon cancers. In this study, the antitumourigenic effects of ZER were assessed in rats induced to develop liver cancer with a single intraperitoneal injection of diethylnitrosamine (DEN, 200 mg/kg) and dietary 2-acetylaminofluorene (AAF) (0.02%). The rats also received intraperitoneal ZER injections at 15, 30 or 60 mg/kg body wt. twice a week for 11 weeks, beginning week four post-DEN injection. The hepatocytes of positive control (DEN/AAF) rats were smaller with larger hyperchromatic nuclei than normal, showing cytoplasmic granulation and intracytoplasmic violaceous material, which were characteristics of hepatocarcinogenesis. Histopathological evaluations showed that ZER protects the rat liver from the carcinogenic effects of DEN and AAF. Serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (AP) and alpha-fetoprotein (AFP) were significantly lower (P < 0.05) in ZER-treated than untreated rats with liver cancer. The liver malondialdehyde (MDA) concentrations significantly (P < 0.05) increased in the untreated DEN/AAF rats indicating hepatic lipid peroxidation. There was also significant (P < 0.05) reduction in the hepatic tissue glutathione (GSH) concentrations. The liver sections of untreated DEN/AAF rats also showed abundant proliferating cell nuclear antigen (PCNA), while in ZER-treated rats the expression of this antigen was significantly (P < 0.05) lowered. By the TUNEL assay, there were significantly (P < 0.05) higher numbers of apoptotic cells in DEN/AAF rats treated with ZER than those untreated. Zerumbone treatment had also increased Bax and decreased Bcl-2 protein expression in the livers of DEN/AAF rats, which suggested increased apoptosis. Even after 11 weeks of ZER treatment, there was no evidence of abnormality in the liver of normal rats. This study suggests that ZER reduces oxidative stress, inhibits proliferation, induces mitochondria-regulated apoptosis, thus minimising DEN/AAF-induced carcinogenesis in rat liver. Therefore, ZER has great potential in the treatment of liver cancers.     

TRAF6 regulates proliferation, apoptosis, and invasion of osteosarcoma cell

Hepatocellular carcinoma is becoming one of the most prominent types of cancer in the world. Recently, from Styrax japonica Siebold et al. Zuccarini (SJSZ), we isolated a glycoprotein which consists of carbohydrate moiety (52.64%) and protein moiety (42.35%). We evaluated whether SJSZ glycoprotein prevents hepatocarcinogenesis induced by N-nitrosodiethylamine (DEN). The purpose of this study was to evaluate the effect of SJSZ glycoprotein in DEN-induced hepatocarcinogenesis in ICR mice. To know chemopreventive effect of SJSZ glycoprotein on hepatocarcinogenesis, ICR mice were intraperitoneally injected with N-nitrosodiethylamine (DEN, 10 mg/kg) for 7 weeks. After sacrifice, we evaluated indicators of liver tissue damage [the activities of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and thiobarbituric acid reactive substances (TBARS)], antioxidative enzymes [activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)], and initiating hepatocarcinogenic indicator [heat shock protein (HSP) 27 and 70] and hepatocarcinogenic signals [protein kinase C (PKC), extracellular signal-regulating kinase (ERK) 1/2, nuclear factor (NF)-κB (p50 and p65) and tumor necrosis factor-α (TNF-α)] using biochemical methods, immunoblot analysis, and RT-PCR. The results obtained from this study revealed that SJSZ glycoprotein (10 mg/kg, BW) decreased the levels of LDH, ALT, and TBARS, whereas the activities of SOD, GPx, and CAT increased in the DEN-induced ICR mice. With respect to the hepatocarcinogenic indicator and hepatocarcinogenic signals, HSP27, HSP70, PKC, ERK1/2, NF-κB (p50 and p65), and TNF-α, activity decreased. Hence, SJSZ glycoprotein might prevent expression of HSP27 and HSP70 by DEN.     

白藜芦醇通过糖代谢重编程抑制DEN诱导大鼠肝细胞癌前阶段的恶性增殖

白藜芦醇(resveratrol,RES)可抑制肝癌细胞的生长与增殖。但其在癌前阶段的作用尚不十分清楚。本文研究白藜芦醇对二乙基亚硝胺(diethylinitrosamine, DEN)诱导大鼠肝癌前阶段的作用及机制。SD大鼠分为正常对照组、RES处理组、DEN处理组和RES-DEN处理组。研究结果表明,DEN处理大鼠8周时,肝细胞的总增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)升高至2倍(P<0.05),核内PCNA蛋白表达水平升高至3倍(P<0.001),而RES-DEN处理组大鼠肝细胞总PCNA(P<0.05)和核内PCNA蛋白表达水平(P<0.001)降低。结果提示,RES可显著抑制肝细胞恶性增生。通过非靶向代谢物组学及代谢通路富集分析,结果表明,RES-DEN处理大鼠的肝细胞中,虽然磷酸戊糖途径向糖酵解途径的转变增强,但相较于DEN组大鼠,糖酵解水平并未出现显著提高,提示磷酸烯醇式丙酮酸-丙酮酸-乳酸这条代谢途径被抑制。进一步验证发现,这条代谢途径上的关键酶M2型丙酮酸激酶(M2-type pyruvate kinase,PKM2)和乳酸脱氢酶(lactate dehydrogenase,LDHA)蛋白质表达水平被抑制(P<0.05)。RES可通过调节糖代谢重编程,在肝癌的癌前阶段抑制DEN诱导的大鼠肝细胞的过度增殖,为RES预防肝癌提供了实验依据。     

Sodium selenite modulates tumour marker indices in N-nitrosodiethylamine-initiated and phenobarbital-promoted rat liver carcinogenesis

The effect of sodium selenite (Se) was investigated against two-stage rat liver carcinogenesis initiated by a single intraperitoneal injection of N-nitrosodiethylamine (DEN, 200 mg kg(-1) i.p.) followed by promotion with phenobarbital (PB, 0.05%) in a basal diet. Se (4 p.p.m.) was administered per os daily throughout the entire experiment, before the initiation, or during the promotion stage. The plasma, liver (hepatoma and surrounding tissue) and kidney tissue were investigated biochemically for lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and 5'-nucleotidase. These enzyme activities were increased (p < 0.001) in plasma of hepatoma-bearing rats compared with normal control rats. The elevation of these enzyme activities in plasma was indicative of the persistent deteriorating effect of DEN in cancer-bearing animals. Aminotransferase levels were decreased in hepatoma and surrounding liver tissue, whereas lactate dehydrogenase, alkaline phosphatase and 5'-nucleotidase were increased in the cancer condition. These enzyme activities were reversed to near normal control values in animals treated with Se. It is apparent that the beneficial effect of Se is primarily exerted on the initiation phase and secondarily during the promotion stage of DEN-initiated rat liver carcinogenesis. The analysis of marker enzyme activities taken together with our previous findings clearly indicates the antitumour efficacy of sodium selenite on DEN-induced hepatoma animals.     

Dietary influence of selenium on the incidence of N-nitrosodiethylamine-induced hepatoma with reference to drug and glutathione metabolizing enzymes

The dietary administration of selenium (sodium selenite; 4 p.p.m.) daily has been found to be highly effective in reducing the incidence of cancer induced by N-nitrosodiethylamine (DEN) in Wistar strain rats. Selenium treatment either before initiation, during initiation and selection/phenobarbital promotion phases of hepatocarcinogenesis has been found to be effective in elevating hepatic microsomal cytochrome b(5), NADPH-cytochrome C reductase and cytosolic aryl hydrocarbon hydroxylase activities to a statistically significant level measured either in the hyperplastic nodule or in the surrounding liver tissues compared to control animals. Moreover, selenium treatment throughout the study, decreases the cytosolic glutathione S-transferase and microsomal UDP-glucuronyl transferase activities by a significant degree when compared to control rats. Alterations in glutathione metabolizing enzyme activities (glutathione reductase, gamma-glutamyl transpeptidase, gamma-glutamylcysteine synthetase and glucose-6-phosphate dehydrogenase) were also observed in selenium-treated groups. Our results confirm the fact that selenium is particularly protective in limiting the action of DEN during the initiation phase of hepatocarcinogenesis.     

Supplementation of selenium reduces chemical hepatocarcinogenesis in male Sprague-Dawley rats

Selenium is an essential micronutrient mineral found mainly in soils and has been shown to prevent certain cancers in humans and animals. However, the dose and effects of selenium on liver cancer are controversial. The aim of this study was to investigate the effects of sodium selenite (4 mg/kg in drinking water) on chemically induced hepatocarcinogenesis in rats. Hepatocarcinogenesis was induced by a single intraperitoneal injection of diethyl nitrosamine (DEN) (200 mg/kg body weight) and 2 weeks later, the carcinogenic effect was promoted by 2-acetylaminofluorene (2-AAF) (0.02%). 44 Sprague-Dawley rats were divided into 6 groups: negative control, positive control (DEN+2-AAF), pre-selenium group (sodium selenite for 4 weeks, then DEN+2-AAF), pre-selenium control group (sodium selenite for 4 weeks, no DEN or 2-AAF), post-selenium group (sodium selenite for 8 weeks after 4 weeks of DEN injection) and post-selenium control group (sodium selenite for 8 weeks, no DEN or 2-AAF). Hematoxylin and eosin plus Gordon and Sweet’s methods were used to stain liver tissues. The results showed that the number and sizes of hepatic nodules in pre- and post-selenium treatment groups significantly decreased (P<0.05) compared with the positive control. Microscopic analysis of pre- and post-selenium groups showed that the majority of nodules were hyperplastic with preserved liver architecture, whereas the positive control was full of neoplastic nodules with a completely disrupted liver architecture. Hence, pre- and post-selenium treatments can reduce the extent of liver cancer on chemically induced hepatocarcinogenesis in rats.     

Chemopreventive effect of vanadium in a rodent model of chemical hepatocarcinogenesis: reflections in oxidative DNA damage, energy-dispersive X-ray fluorescence profile and metallothionein expression

In the present study, we investigated the antitumour efficacy of vanadium in a defined rodent model of experimental hepatocarcinogenesis. Hepatic preneoplasia was induced in male Sprague-Dawley rats with a single, necrogenic, intraperitoneal injection of diethylnitrosamine (DEN) (200 mg/kg body weight) followed by promotion with phenobarbital (PB). The levels of modified DNA bases 8-hydroxy-2′-deoxyguanosine (8-OHdG), a potential marker involved in the initiation of carcinogenesis, were measured by high-performance liquid chromatography, whereas tissue trace element status and expression of metallothionein (MT), a Cu–Zn metalloprotein associated with neoplastic cell growth and subsequent development of premalignant phenotype of the cell, were studied by energy-dispersive X-ray fluorescence spectrometry and enzyme-coupled immunohistochemistry, respectively. There was a significant and steady elevation of modified bases (8-OHdG) along with substantial increase in MT immunoexpression and disturbance in trace element homeostasis following DEN exposure. Supplementation of vanadium at a dose of 0.5 ppm for four consecutive weeks strictly abated the formation of 8-OHdG (P < 0.0001; 81.28%) in preneoplastic rat liver. In a long-term DEN plus PB regimen, vanadium was able to limit in situ MT expression with a concomitant decrease in MT immunoreactivity (P < 0.05). Furthermore, vanadium treatment throughout the study restored hepatic levels of essential trace elements and decreased nodular incidence (58.34%) and nodule multiplicity (P < 0.001; 66.89%) in rats treated with DEN plus PB. Taken together, the study provides evidence in support of the chemopreventive potential of vanadium in limiting neoplastic transformation during the preneoplastic stages of hepatocarcinogenesis in rats.     

The inhibitory effect of sodium selenite on N-nitrosodiethylamine-induced and phenobarbital promoted liver tumourigenesis in rats based on the modulation of polyamine levels

In the present study, we have evaluated the effects of dietary selenite (Se) on polyamine levels and its influence on N-nitrosodiethylamine (DEN) initiated and Phenobarbital (PB) promoted in rat liver carcinogenesis. Dietary selenite at a concentration of 4 ppm (through drinking water) was administered in rats either before initiation (4 weeks), or during promotion (16 weeks) and entire experimental period (20 weeks). Male Wistar strain of albino rats was treated with single intra peritoneal dose of DEN (200 mg kg⁻¹ body weight), after 2 weeks the carcinogenic effect was promoted by PB (0.05%; through diet). Alpha fetoprotein (AFP) was investigated after the 20th-week of experimental period. Selenite-treated animals markedly reduced the AFP during the time of pre-selenite [before initiation (4 weeks)] and entire experimental period (20 weeks), administration rather than the promotion period. This infers that anticancer property of selenite depends on the stage of carcinogenesis, rather than duration of treatment. Evaluation of polyamine levels in hepatoma and surrounding liver tissue showed significant difference in the selenite-treated groups compared with pair-fed control groups. Furthermore, histopathological examination showing remarkable difference between control and treated groups. These results demonstrate that selenite can modulate the development of DEN-induced and PB-promoted rat liver carcinogenesis through a polyamine-dependent mechanism. (Mol Cell Biochem xxx: 165–172, 2005)     

Protective effects of Ginkgo biloba against rat liver carcinogenesis

Ginkgo biloba (EGb) has been proposed as a promising candidate for cancer chemoprevention and has shown protective effects on the liver against chemically induced oxidative injury and fibrosis. The potential beneficial effects of EGb were investigated in two rat liver carcinogenesis bioassays induced by diethylnitrosamine (DEN). In a short-term study for anti-initiating screening, male Wistar rats were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb and initiated 14 days later with a single dose of DEN (100 mg/kg i.p.). The respective groups were killed 24h or 2 weeks after DEN-initiation. Liver samples were collected for the analysis of proliferating cell nuclear antigen (PCNA), transforming growth factor alpha (TGF-alpha), p53, apoptosis and induction of single hepatocytes and minifoci positive for the enzyme glutathione S-transferase P-form (GST-P). In a medium-term study for anti-promoting screening, the animals received a single dose of DEN (200 mg/kg i.p.) and, 2 weeks later, were fed a basal diet or supplemented diet with 500 or 1000 ppm EGb for 6 weeks. All animals underwent 70% partial hepatectomy (PH) at week 3 and killed at week 8. Liver samples were collected to analyze development of preneoplastic foci of altered hepatocytes (FAH) expressing GST-P. In the short-term study, pretreatment of rats with 1000 ppm EGb significantly reduced the rates of cell proliferation, apoptosis and p53, TGF-alpha immunoreactivity and the number of GST-P-positive hepatocytes. In the medium-term study, EGb treatment during the post-initiation stage failed to reduce the development of DEN-induced GST-P-positive foci. Thus, EGb presented inhibitory actions during initiation but not promotion of rat liver carcinogenesis induced by DEN.     

Changes in gap junction protein (connexin 32) gene expression during rat liver carcinogenesis

A rat liver gap junction (GJ) cDNA probe that detects mRNA encoding the 32 Kd GJ-protein (connexin 32) was employed to study GJ-protein gene expression in rat liver tumors induced by a single exposure to diethylnitrosamine (DEN) followed by exposure to 2-acetylaminofluorene (AAF)/CCl4/AAF or induced by systemic administration of N-ethyl-N-hydroxyethylnitrosamine (EHEN). All carcinomas generated by these carcinogens showed markedly reduced levels of GJ-protein mRNA. This may indicate that GJ-protein levels and gap-junctional intercellular communication (GJIC) capacity are also severely compromised. Moreover, all hyperplastic nodules also showed a reduced level of GJ-protein mRNA. Taken together with our earlier finding that the liver tumor promoter phenobarbital inhibits GJ-protein gene expression, these results suggest that deranged GJIC is a relatively early event in liver multistage carcinogenesis. A range of other cDNA probes was also used to characterize gene expression in the DEN-induced tumors. Induction of expression was seen for glutathione S-transferase (placental form) (GST-P), gamma-glutamyltranspeptidase (GGT), and c-raf but not for c-Ha-ras or c-myc.     

Resveratrol ameliorates oxidative DNA damage and protects against acrylamide-induced oxidative stress in rats

Acrylamide (ACR), used in many fields from industrial manufacturing to laboratory personnel work is also formed during the heating process through interactions of amino acids. Therefore ACR poses a significant risk to human health. This study aimed to elucidate whether resveratrol (RVT) treatment could modulate ACR-induced oxidative DNA damage and oxidative changes in rat brain, lung, liver, kidney and testes tissues. Rats were divided into four groups as control (C); RVT (30 mg/kg i.p. dissolved in 0.9% NaCl), ACR (40 mg/kg i.p.) and RVT + ACR groups. After 10 days rats were decapitated and tissues were excised. 8-hydroxydeoxyguanosine (8-OHdG) is a biomarker of oxidative DNA damage. 8-OHdG content in the extracted DNA solution was determined by enzyme-linked immunosorbent assay method. Malondialdehyde (MDA), glutathione (GSH) levels and myeloperoxidase activity (MPO) were determined in tissues, while oxidant-induced tissue fibrosis was determined by collagen contents. Serum enzyme activities, cytokine levels, leukocyte apoptosis were assayed in plasma. As an indicator of oxidative DNA damage, 8-OHdG levels significantly increased in ACR group and this was reversed significantly by RVT treatment. In ACR group, GSH levels decreased significantly while the MDA levels, MPO activity and collagen content increased in the tissues suggesting oxidative organ damage. In RVT-treated ACR group, oxidant responses reversed significantly. Serum enzyme activities, cytokine levels and leukocyte late apoptosis which increased following ACR administration, decreased with RVT treatment. Therefore supplementing with RVT can be useful in individuals at risk of ACR toxicity.     

Effect of Solanum trilobatum on the antioxidant status during diethyl nitrosamine induced and phenobarbital promoted hepatocarcinogenesis in rat

AIM: The methanolic extract of Solanum trilobatum (ST) is cytotoxic and exerts an inhibitory effect on tumor growth and in the present study, its role on the antioxidant status of N-diethylnitrosamine (DEN) induced and phenobarbital (PB) promoted hepatocarcinogenesis was assessed. METHODS: The protective role of ST on DEN induced and PB promoted hepatocarcinogenesis in Wistar rats was assessed from total nodular incidence, nodule multiplicity and volume of persistent nodules after an experimental period of 3 and 6 months following co-administration. The levels of thiobarbituric reactive substances (TBARS), glutathione (GSH) and activities of antioxidant enzymes were assessed in the haemolysate and liver of experimental animals to evaluate the antioxidant status. RESULTS: In DEN+PB+ST animals, the nodular incidence, multiplicity and volume reduced significantly compared to DEN+PB treated animals. In DEN+PB animals, the levels of TBARS increased significantly, whereas the levels of GSH and the activities of antioxidant enzymes-superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glucose 6 phosphate dehydrogenase showed significant alterations compared to control both in the haemolysate and liver. However, in DEN+PB+ST animals, the levels of TBARS decreased significantly and the levels of GSH increased with favorable alterations in the activities of antioxidant enzymes in both the haemolysate and liver. CONCLUSION: The present results suggest that ST exerts its chemopreventive effects by modulating the antioxidant status during DEN induced hepatocarcinogenesis.     

Nicotinamide and heat preconditioning – Effects on hepatic HSP70, carbohydrate and oxidative disturbances in STZ-induced diabetic rats

ObjectiveNicotinamide (NA) is known to have antioxidant potential and partially to protect insulin-secreting cells against diabetogenic agent STZ (streptozotocin). In a combination to heat stress (HS), NA is also known to induce heat-shock proteins (HSPs) production. Heat preconditioning (HP) and HSPs have cytoprotective effects against development of cellular injury caused by application of subsequent stressor. We aimed to determine if pretreatment with NA and HP (as HSP70 –inducers) can affect STZ-induced diabetic disturbances in rats.MethodsNA-pretreatment (250 mg/kg b.w., 7 days) and heat preconditioning (41 ± 1 °C, 45 min) of diabetic rats was performed. The changes in hepatic carbohydrate- and antioxidative-related enzymes and substrates were investigated.ResultsNA-pretreatment, alone or in combination with HS, resulted in significant increase of HSP70 concentration in the liver of control and diabetic rats. Compared to diabetic controls, pretreatment with NA, in combination with HP, resulted in decrease of blood and liver glucose, increase of glycogen and glucose-6-phosphate level, increase of glycogenolytic/glycolytic enzymes, decrease of gluconeogenic enzymes, as well as an increase of glutathione content and glutathione peroxidase, decrease of glutathione reductase and catalase activities.ConclusionsNA is a potent HSP70 coinducer, alone or in a combination with HS in the liver of both control and diabetic rats. Pretreatment with NA, accompanied by HP, has a pronounced corrective effect on STZ-induced diabetes disturbances in the key hepatic carbohydrate- and antioxidative-related parameters. It seems that this corrective effect is based on the increased production of hepatic HSP70.     

Heat Shock Preconditioning Reduces the Formation of 8-hydroxy-2′-deoxyguanosine and 4-hydroxy-2-nonenal Modified Proteins in Ischemia-reperfused Liver of Rats

Heat shock preconditioning (HSPC) is a promising strategy for providing ischemic tolerance. The objective of this study is to investigate the effectiveness of HSPC in preventing oxidative damage of cellular proteins and DNA during ischemia-reperfusion of the liver. Male Wistar rats were divided into a heat shock group (group HS) and control (group C). Forty-eight hours prior to ischemia, rats in group HS received HSPC at 42°C for 15 &#117 min. All rats received hepatic warm ischemia for 30 &#117 min and subsequent reperfusion. The formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal (HNE) modified proteins in liver tissue, survival rate of the animals, and changes in biochemical and histological parameters were compared between groups. Heat shock protein 72 was produced only in group HS. The 7-day survival of rats was significantly better in group HS (10/10) than in group C (5/10) ( p <0.01). The serum release of alanine aminotransferase ( n =10, p <0.01) and the concentration of adenosine triphosphate in liver tissue ( n =10, p <0.01) 40 &#117 min after reperfusion was significantly better in group HS than in group C. The formation of 8-OHdG in liver tissue measured by high-performance liquid chromatography was suppressed in group HS ( p <0.01). The production of HNE-modified proteins as determined by Western-blot analysis was also decreased in group HS. These results were also confirmed by immunohistochemical analysis. As determined by levels of 8-OHdG and HNE-modified proteins produced during ischemia-reperfusion of the liver, HSPC reduced the oxidative injury of cellular proteins and DNA in the liver tissue.     

Effects of crude extracts of Agaricus blazei on DNA damage and on rat liver carcinogenesis induced by diethylnitrosamine

The effects of crude extracts of the mushroom Agaricus blazei Murrill (Agaricaceae) on both DNA damage and placental form glutathione S-transferase (GST-P)-positive liver foci induced by diethylnitrosamine (DEN) were investigated. Six groups of adult male Wistar rats were used. For two weeks, animals of groups 3 to 6 were treated with three aqueous solutions of A. blazei (mean dry weight of solids being 1.2, 5.6, 11.5 and 11.5 mg/ml, respectively). After this period, groups 2 to 5 were given a single ip injection 200 mg/kg DEN and groups 1 and 6 were treated with 0.9% NaCl. All animals were subjected to 70% partial hepatectomy at week five and sacrificed 4, 24 and 48 h or 8 weeks after DEN or 0.9% NaCl treatments (10th week after the beginning of the experiment). The alkaline comet assay and GST-P-positive liver foci development were used to evaluate the influence of the mushroom extracts on liver cell DNA damage and on the initiation of liver carcinogenesis, respectively. Previous treatment with the highest concentration of A. blazei (11.5 mg/ml) significantly reduced DNA damage, indicating a protective effect against DEN-induced liver cytotoxicity/genotoxicity. However, the same dose of mushroom extract significantly increased the number of GST-P-positive liver foci.     

Protective effect of Cassia fistula Linn. on diethylnitrosamine induced hepatocellular damage and oxidative stress in ethanol pretreated rats

Diethylnitrosamine (DEN), found in many commonly consumed foods, is widely reported to induce cancer in animals and humans. The aim of the present study was to investigate the hepatoprotective and antioxidant activities of the leaf extract of the medicinal plant Cassia fistula Linn. against diethylnitrosamine induced liver injury in ethanol pretreated rats. Albino Wistar rats, pretreated with ethanol for 15 days, were administered a single dose of DEN. Thirty days after DEN administration, hepatotocellular damage was observed histologically, along with elevated levels of serum AST, ALT, ALP, LDH, γ-GT and bilirubin and a simultaneous fall in the levels of the marker enzymes in the liver tissue. Liver oxidative stress was confirmed by elevated levels of lipid peroxidation (LPO) and a decrease in enzymic and non-enzymic antioxidants activities. Oral administration of the ethanolic leaf extract (ELE) of Cassia fistula for 30 days to ethanol + DEN treated rats significantly improved the above alterations in the markers of hepatotoxicity and oxidative stress, resulting in the reversal of most of the parameters studied and were comparable to the standard hepatoprotective drug silymarin.