Garlic Oil Suppressed Nitrosodiethylamine-Induced Hepatocarcinoma in Rats by Inhibiting PI3K-AKT-NF-κB Pathway

To explore the underlying mechanisms for the protective effects of garlic oil (GO) against nitrosodiethylamine (NDEA)-induced hepatocarcinoma, 60 male Wistar rats were randomized into 4 groups (n=15): control group, NDEA group, and two GO plus NDEA groups. The rats in GO plus NDEA groups were pretreated with GO (20 or 40 mg/kg) for 7 days. Then, all rats except those in control group were gavaged with NDEA for 20 weeks, and the rats in GO plus NDEA groups were continuously administered with GO. The results showed that GO co-treatment significantly suppressed the NDEA-induced increases of alpha fetal protein (AFP) level in serum, nuclear atypia in H&E staining, sirius red-positive areas and proliferating cell nuclear antigen (PCNA) expression. The molecular mechanisms exploration revealed that the protein levels of phosphatidylinositol 3 kinase (PI3K)-p85, PI3K-p110, total AKT, p-AKT (Ser473) and p-AKT (Thr308) in the liver of NDEA group rats were higher than those in control group rats. In addition, NDEA treatment induced IκB degradation and NF-κB p65 phosphorylation, and up-regulated the protein levels of downstream pro-inflammatory mediators. GO co-treatment significantly reversed all the above adverse effects induced by NDEA. These results suggested that the protective effects of GO against NDEA-induced hepatocarcinoma might be associated with the suppression of PI3K- AKT-NF-κB pathway.     

Hepatic and renal oxidative stress in acute toxicity of N-nitrosodiethylamine in rats

Nitrosoamines such as N-nitrosodiethylamine (NDEA) produce oxidative stress due to generation of reactive oxygen species and may alter antioxidant defence system in the tissues. NDEA was administered ip as a single dose to rats in LD50 or in lower amounts and the animals were sacrificed after 0-48 hr of treatment. The results showed that lipid peroxidation in liver increased, however no significant increase in kidney LPO was observed after NDEA administration. Superoxide dismutase (SOD) and glutathione reductase (GSH-R) activity increased in liver, however, catalase (CAT) activity in liver was inhibited in NDEA treated rats. Kidney showed an increase in SOD activity after an initial decrease along with increase in GSH-R activity in NDEA treated rats. However, kidney CAT activity was not significantly altered in NDEA intoxicated rats. Serum transaminases, serum alkaline phosphatase blood urea nitrogen, serum creatinine and scrum proteins were elevated in NDEA treated rats. The results indicate NDEA-induced oxidative stress and alteration in antioxidant enzymes in liver and kidney to neutralise oxidative stress.     

Garlic Oil Attenuated Nitrosodiethylamine-Induced Hepatocarcinogenesis by Modulating the Metabolic Activation and Detoxification Enzymes

Nitrosodiethylamine (NDEA) is a potent carcinogen widely existing in the environment. Our previous study has demonstrated that garlic oil (GO) could prevent NDEA-induced hepatocarcinogenesis in rats, but the underlying mechanisms are not fully understood. It has been well documented that the metabolic activation may play important roles in NDEA-induced hepatocarcinogenesis. Therefore, we designed the current study to explore the potential mechanisms by investigating the changes of hepatic phase Ⅰ enzymes (including cytochrome P450 enzyme (CYP) 2E1, CYP1A2 and CYP1A1) and phase Ⅱ enzymes (including glutathione S transferases (GSTs) and UDP- Glucuronosyltransferases (UGTs)) by using enzymatic methods, real-time PCR, and western blotting analysis. We found that NDEA treatment resulted in significant decreases of the activities of CYP2E1, CYP1A2, GST alpha, GST mu, UGTs and increases of the activities of CYP1A1 and GST pi. Furthermore, the mRNA and protein levels of CYP2E1, CYP1A2, GST alpha, GST mu and UGT1A6 in the liver of NDEA-treated rats were significantly decreased compared with those of the control group rats, while the mRNA and protein levels of CYP1A1 and GST pi were dramatically increased. Interestingly, all these adverse effects induced by NDEA were simultaneously and significantly suppressed by GO co-treatment. These data suggest that the protective effects of GO against NDEA-induced hepatocarcinogenesis might be, at least partially, attributed to the modulation of phase I and phase II enzymes.     

24-hour rhythms in oxidative stress during hepatocarcinogenesis in rats: effect of melatonin or alpha-ketoglutarate

To compare the effects of alpha-ketoglutarate (alpha-KG) and melatonin on 24-h rhythmicity of oxidative stress in N-nitrosodiethylamine (NDEA)-injected Wistar male rats, melatonin (5 mg/kg i.p.) or alpha-KG (2 g/kg through an intragastric tube) was given daily for 20 weeks. In blood collected at 6 time points during a 24-h period, serum activity of aspartate transaminase (AST) and alanine transaminase (ALT) and the levels of alpha-fetoprotein (alpha-FP) were measured as markers of liver function. To assess lipid peroxidation and the antioxidant status, plasma levels of thiobarbituric acid reactive substances (TBARS) and of reduced glutathione (GSH) were measured, together with the activity of erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST). NDEA augmented mesor and amplitude of rhythms in AST and ALT activity and plasma alpha-FP levels and mesor values of plasma TBARS, while decreasing mesor values of plasma GSH and erythrocyte SOD, CAT, GPx and GST. Acrophases were delayed by NDEA in all cases except for alpha-FP rhythm, which became phase-advanced. Co-administration of melatonin or alpha-KG partially counteracted the effects of NDEA. Melatonin decreased mesor of plasma TBARS and augmented mesor of SOD activity. The results indicate that melatonin and alpha-KG are effective in protecting from NDEA-induced perturbation of 24-h rhythms in oxidative stress. Melatonin augmented antioxidant defense in rats.     

Potential chemoprevention of N-nitrosodiethylamine-induced hepatocarcinogenesis by polyphenolics from Acacia nilotica bark

Chemopreventive potential of Acacia nilotica bark extract (ANBE) against single intraperitoneal injection of N-nitrosodiethylamine (NDEA, 200 mg/kg) followed by weekly subcutaneous injections of carbon tetrachloride (CCl₄, 3 ml/kg) for 6 weeks induced hepatocellular carcinoma (HCC) in rats was studied. At 45 day after administration of NDEA, 100 and 200 mg/kg of ANBE were administered orally once daily for 10 weeks. The levels of liver injury and liver cancer markers such as alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), total bilirubin level (TBL), α-feto protein (AFP) and carcinoembryonic antigen (CEA) were substantially increased following NDEA treatment. However, ANBE treatment reduced liver injury and restored liver cancer markers. ANBE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which was dose dependent. Additionally, ANBE also increased the activities of antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) in the liver of NDEA-administered rats. Eventually, ANBE also significantly improved body weight and prevented increase of relative liver weight due to NDEA treatment. Histological observations of liver tissues too correlated with the biochemical observations. HPLC analysis of ANBE showed the presence of gallic, protocatechuic, caffeic and ellagic acids, and also quercetin in ANBE. The results strongly support that A. nilotica bark prevents lipid peroxidation (LPO) and promote the enzymatic and non-enzymatic antioxidant defense system during NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by the phytomolecules in ANBE.     

Protective role of Vitamin E pre-treatment on N-nitrosodiethylamine induced oxidative stress in rat liver

Nitrosamine compounds are known hepatic carcinogens. In the metabolism of nitrosamines, such as N-nitrosodiethylamine (NDEA), there is evidence of the formation of reactive oxygen species (ROS) resulting in oxidative stress, which may be one of the factors in the etiology of cancer. The formation of ROS may alter the antioxidant system, while the presence of Vitamin E may counteract NDEA induced oxidative stress. This study was planned to determine whether pre-treatment with Vitamin E (40 mg/kg body weight, i.p., twice a week for 4 weeks) to NDEA induced rats provides protection against oxidative stress in liver caused by the carcinogen. A single necrogenic dose of NDEA (200mg/kg body weight) was administered i.p. to the male albino rats with or without Vitamin E pre-treatment and the animals were sacrificed on Days 7, 14 or 21 after the administration of NDEA. The result showed enhanced levels of hepatic lipid peroxidation (LPO) and conjugated dienes of NDEA treated rats as the indices of oxidative stress, however, Vitamin E pre-treated rats administered NDEA showed decreased LPO and conjugated dienes (Day 21). Superoxide dismutase (SOD) activity in liver was not altered significantly in NDEA treated rats with or without Vitamin E pre-treatment. Catalase (CAT) activity was inhibited with NDEA treatment, however, Vitamin E pre-treatment showed recovery in hepatic CAT activity (Days 14 and 21). Total and Se-glutathione peroxidase (GSH-Px) activities and glutathione-S-transferase (GST) activity in liver increased in NDEA treated rats irrespective of Vitamin E pre-treatment. Glutathione reductase (GSH-R) activity as well as total glutathione (GSH) content in liver decreased in NDEA treated animals, both of which were recovered in Vitamin E pre-treated rats administered NDEA. Activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were increased significantly following NDEA treatment to rats with or without Vitamin E pre-treatment. The activities of AST and ALT enzymes were significantly reduced on Days 14 and 21 and ALP activity was reduced on Day 21 in NDEA+Vitamin E treated animals when compared to NDEA treated alone. LDH enzyme activity was normalized on Day 14 in Vitamin E pre-treated animals administered NDEA. However, the AST, ALT and ALP enzyme activities remained high in all treatment groups as compared to control group. Normal control and Vitamin E treated alone rats revealed normal histology of liver. On the other hand, NDEA treated animals showed alterations in normal hepatic histoarchitecture, which comprised of necrosis and vacuolization of the cells. However, the rats treated with Vitamin E+NDEA showed that the liver cells were normal, with very little necrosis (Day 21). This study concludes that the pre-treatment with Vitamin E prior to the administration of NDEA, reduced the degree of oxidative stress, although this vitamin produced only slight changes in the hepatic injury, in a time-dependent manner.     

Prevention of N-nitrosodiethylamine-induced hepatocarcinogenesis by S-allylcysteine

Chemopreventive effect of S-allylcysteine (constituent of garlic) on N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis was evaluated in Wistar rats. Significantly decreased lipid peroxidation products (thiobarbituric acid reactive substances-TBARS and lipid hydroperoxides) with increased level of reduced glutathione, increased activities of glutathione S-transferase, and glutathione peroxidase were observed in liver of NDEA-treated rats when compared with control rats. The activities of superoxide dismutase and catalase were significantly decreased in tumor tissue when compared with control. Administration of S-allylcysteine (SAC) showed the inhibition of tumor incidence, modulated the lipid peroxidation, and increased the reduced glutathione, glutathione-dependent enzymes, superoxide dismutase, and catalase in NDEA-induced carcinogenesis. From our results, we speculate that S-allylcysteine mediates its chemopreventive effects by modulating lipid peroxidation, GST stimulation, and by increasing the antioxidants. Hence SAC prevents cells from loss of oxidative capacity in NDEA-induced hepatocarcinogenesis.     

The protective role of ellagitannins flavonoids pretreatment against N-nitrosodiethylamine induced-hepatocellular carcinoma

Ellagitannins are esters of glucose with hexahydroxydiphenic acid; when hydrolyzed, they yield ellagic acid (EA), the dilactone of hexahydroxydiphenic acid. EA has been receiving the most attention, because it has potent antioxidant activity, radical scavenging capacity, chemopreventive and antiapoptotic properties. Hepatocellular carcinoma (HCC) is the most frequent primary malignancy of liver, and accounts for as many as one million deaths worldwide in a year. The aim of the present study was to evaluate the antioxidant and chemopreventive efficiency of ellagic acid against N-nitrosodiethylamine (NDEA) induced hepatocarcinogenesis in rats. Rats were classified into four groups as follows: normal control group, group injected i.p. with a single dose (200 mg/kg b.wt.) of NDEA, third group daily administered orally EA with a dose of 50 mg/kg b.wt. for 7 days before and 14 days after NDEA administration, and fourth group received a similar dose of EA for 21 days after the dose of NDEA administration. The model of NDEA-injected hepatocellular carcinomic (HCC) rats elicited significant declines in liver antioxidant enzyme activities; glutathione peroxidase (GPX), gamma glutamyl transferase (γ-GT) and glutathione-S-transferase (GST), with a reduction in reduced glutathione (GSH) and serum total protein with concomitant significant elevations in tumor markers arginase and α-l-fucosidase, and liver enzymes; aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PD), direct and total bilirubin. The oral administration of EA as a protective agent, produced significant increases in tested antioxidant enzyme activities and serum total protein concomitant with significant decreases in the levels of tumor markers arginase and α-l-fucosidase as well as liver enzymes, direct and total bilirubin. Similarly, the oral administration of EA, as a curative agent produced similar changes to those when EA was used as a protective agent, but to a lesser extent. In addition, it was noted that HCC rats exhibited a degree of DNA fragmentation; however, EA administration partially inhibited the DNA fragmentation. Therefore, EA has the ability to scavenge free radicals, prevent DNA fragmentation, reduce liver injury and protect against oxidative stress.     

Protective Effect of Naringenin Against Lead-Induced Oxidative Stress in Rats

Oxidative stress is thought to be involved in lead-induced toxicity. The aim of this study was to investigate the possible protective role of naringenin on lead-induced oxidative stress in the liver and kidney of rats. In the present investigation, lead acetate (500 mg Pb/L) was administered orally for 8 weeks to induce hepatotoxicity and nephrotoxicity. The levels of hepatic and renal markers such as alanine aminotransferase, aspartate aminotransferase, urea, uric acid, and creatinine were significantly (P < 0.05) increased following lead acetate administration. Lead-induced oxidative stress in liver and kidney tissue was indicated by a significant (P < 0.05) increase in the level of maleic dialdehyde and decreased levels of reduced glutathione, superoxide dismutase, catalase, and glutathione peroxidase. Naringenin markedly attenuated lead-induced biochemical alterations in serum, liver, and kidney tissues (P < 0.05). The present study suggests that naringenin shows antioxidant activity and plays a protective role against lead-induced oxidative damage in the liver and kidney of rats.     

Ameliorative effect of 20-OH ecdysone on streptozotocin induced oxidative stress and β-cell damage in experimental hyperglycemic rats

The present study was to evaluate the effects of 20-OH ecdysone on hyperglycemia mediated oxidative stress in streptozotocin induced diabetic rats. Diabetes was induced in experimental rats by single intraperitoneal injection of STZ (45 mg/kg b.w.) dissolved in 0.1 mol/L citrate buffer (pH 4.5). Diabetic rats exhibited increased blood glucose with significant decrease in plasma insulin levels. The activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and the levels of non-enzymic antioxidants vitamin C, vitamin E and reduced glutathione (GSH) were decreased while increases in the levels of LPO markers were observed in liver and kidney tissues of diabetic rats. Moreover, hepatic markers (aspartate aminotransferase and alanine aminotransferase) and renal markers (urea, creatinine) were significantly increased in diabetic rats as compared to control rats. Upon treatment with 20-OH ecdysone to diabetic rats showed significant ameliorative effects on all the biochemical parameters studied. Biochemical findings were supported by histological studies. These results indicated that 20-OH ecdysone exerts a protective action on pancreatic beta cell function and overcomes oxidative stress through its hypoglycemic potential. The effect produced by the 20-OH ecdysone on various parameters was comparable to that of glibenclamide – an antidiabetic drug.     

The chemopreventive effect of Ginkgo biloba and Silybum marianum extracts on hepatocarcinogenesis in rats

Background/objective

This study was designed to evaluate the potential chemopreventive activities of Ginkgo biloba extract (EGb) and Silybum marianum extract (silymarin) against hepatocarcinogenesis induced by N-nitrosodiethylamine (NDEA) in rats.

Methods

Rats were divided into 6 groups. Group 1 served as normal control rats. Group 2 animals were intragastrically administrated NDEA at a dose of 10 mg/kg five times a week for 12 weeks to induce hepatocellular carcinoma (HCC). Groups 3 and 4 animals were pretreated with silymarin and EGb respectively. Groups 5 and 6 animals were posttreated with silymarin and EGb respectively. The investigated parameters in serum are alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyltransferase (GGT) and vascular endothelial growth factor (VEGF). The investigated parameters in liver tissue are malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and comet assay parameters.

Results

In NDEA group, MDA level was elevated with subsequent decrease in GSH level and SOD, GPx and GR activities. In addition, NDEA group revealed a significant increase in serum ALT, AST and GGT activities and VEGF level. Furthermore, NDEA administrated animals showed a marked increase in comet assay parameters. These biochemical alterations induced by NDEA were confirmed by the histopathological examination of rat livers intoxicated with NDEA that showed an obvious cellular damage and well differentiated HCC. In contrast, silymarin+NDEA treated groups (3&;5) and EGb+NDEA treated groups (4&;6) showed a significant decrease in MDA level and a significant increase in GSH content and SOD, GPx and GR activities compared to NDEA group. Silymarin and EGb also beneficially down-regulated the increase in serum ALT, AST, GGT activities and VEGF level induced by NDEA. In addition, silymarin and EGb significantly decreased comet assay parameters. Histopathological examination of rat livers treated with either silymarin or EGb exhibited an improvement in the liver architecture compared to NDEA group.

Conclusions

The obtained findings suggested that silymarin and EGb may have beneficial chemopreventive roles against hepatocarcinogenesis through their antioxidant, antiangiogenic and antigenotoxic activities.     

Suppressive effect of molybdenum on hepatotoxicity of N-nitrosodiethylamine in rats

SUMMARY

In order to elucidate the preventive mechanism of molybdenum (Mo) against carcinogenesis of N-nitroso compounds, the effects of in vivo Mo-pretreatment on N-nitrosodiethylamine (NDEA)-induced hepatotoxicity in rats were examined. Effects of in vitro Mo-pretreatment on NDEA-induced DNA strand breaks and fluctuation of the cytosolic free Ca levels in rat hepatocytes were also investigated. Male Wistar rats weighing 170–190 g were pretreated with 10 ppm Mo as Na₂MoO₄ in deionized drinking water for 21 days, and on day 22, they were exposed to NDEA (50 mg/kg body weight, once, i.p.). 3 and 5 days after NDEA exposure, serum lactic dehydrogenase (LDH) activity, and hepatic calcium (Ca) content and lipid peroxidation levels were evaluated. In vivo Mo-pretreatment prevented NDEA-induced elevations in serum LDH activity and liver Ca content but increased hepatic lipid peroxidation levels. Hepatocytes isolated from rats pretreated with sodium phenobarbital (80 mg/kg body weight, i.p., once a day for 3 days) were exposed to NDEA (0, 100, 250 and 500 μM) in vitro for 30 min at 37°C. NDEA treatment caused DNA strand breaks and a perturbation of cytosolic free Ca level. However, in vitro Mo-pretreatment (20 μM, 20 min at 37°C) suppressed the NDEA-induced DNA damage and disruption of intracellular Ca homeostasis. These results suggest Mo protected against NDEA-induced hepatotoxicity by stimulating the metabolism of the nitroso compound via a nontoxic pathway (denitration) while preventing DNA damage connected with alteration in cytosolic free Ca levels. Thus, the general protective action of Mo against N-nitroso compound-induced carcinogenesis may be explained by a common mechanism.     

Cytoprotective effects of carvedilol against oxygen free radical generation in rat liver

The protective effects of carvedilol, an antihypertensive agent, against oxidative injury caused by acetaminophen were studied in rat liver. Male Wistar rats (250 +/- 30 g) were pre-treated with carvedilol (3.6 mg/kg, p.o.) for 10 days and on the 11th day received an overdose of acetaminophen (800 mg/kg, p.o.). Four hours after acetaminophen administration, blood was collected to determine serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). After that, rats were killed and the livers were excised to determine reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and carbonyl protein contents, and the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione S-transferase (GST), and also the DNA damage index. Acetaminophen significantly increased the levels of TBARS, the DNA damage and SOD, AST and ALT activities. Carvedilol was able to prevent lipid peroxidation, protein carbonilation and DNA fragmentation caused by acetaminophen. Moreover, this drug prevented increases in SOD, AST and ALT activities. These results show that carvedilol exerts cytoprotective effects against oxidative injury caused by acetaminophen in rat liver. These effects are probably related to the O2*- scavenging property of carvedilol or its metabolites.     

Hepatoprotective effect of aqueous extract of Aframomum melegueta on ethanol-induced toxicity in rats

In recent years there have been remarkable developments in the prevention of diseases, especially with regards to the role of free radicals and antioxidants. Ethanol-induced oxidative stress appears to be one mechanism by which ethanol causes liver injury. The protective effect of aqueous plant extract of Aframomum melegueta on ethanol-induced toxicity was investigated in male Wistar rats. The rats were treated with 45 % ethanol (4.8 g/kg b.w.t.) for 16 days to induce alcoholic diseases in the liver. The activities of alanine aminotransferase, aspartate aminotransferase and triglyceride were monitored and the histological changes in liver examined in order to evaluate the protective effects of the plant extract. Hepatic malondialdehyde and reduced glutathione, as well as superoxide dismutase and glutathione-S-transferase activities were determined for the antioxidant status. Chronic ethanol administration resulted in a statistically significant elevation of serum alanine aminotransferases and triglyceride levels, as well as a decrease in reduced glutathione and superoxide dismutase which was dramatically attenuated by the co-administration of the plant extract. Histological changes were related to these indices. Co-administration of the plant extract suppressed the elevation of lipid peroxidation, restored the reduced glutathion, and enhanced the superoxide dismutase activity. These results highlight the ability of Aframomum melegueta to ameliorate oxidative damage in the liver and the observed effects are associated with its antioxidant activities.     

Suppression of N-nitrosodiethylamine induced hepatocarcinogenesis by silymarin in rats

Antioxidants are one of the key players in tumorigenesis, several natural and synthetic antioxidants were shown to have anticancer effects. In the present investigation the efficacy of silymarin on the antioxidant status of N-nitrosodiethylamine (NDEA) induced hepatocarcinogenesis in Wistar albino male rats were assessed. The animals were divided into five groups. The animals in the groups 1 and 3 were normal control and silymarin control, respectively. Groups 2, 4 and 5 were administered with 0.01% NDEA in drinking water for 15 weeks to induce hepatocellular carcinoma (HCC). Starting 1 week prior to NDEA administration group 4 animals were treated with silymarin in diet for 16 weeks, 10 weeks after NDEA administration group 5 animals were treated with silymarin and continued till the end of the experiment period (16 weeks). After the experimental period the body weight, relative liver weight, number of nodules, size of nodules, the levels of lipid peroxidation, glutathione (GSH), and the activities of antioxidant enzymes were assessed in both haemolysate and liver tissue. In group 2 hepatocellular carcinoma induced animals there was an increase in the number of nodules, relative liver weight. The levels of lipid peroxides were elevated with subsequent decrease in the body weight, (glutathione) GSH, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD). In contrast, silymarin + NDEA treated groups 4 and 5 animals showed a significant decrease in the number of nodules with concomitant decrease in the lipid peroxidation status. The levels of GSH and the activities of antioxidant enzymes in both haemolysate and liver were improved when compared with hepatocellular carcinoma induced group 2 animals. The electron microscopy studies were also carried out which supports the chemopreventive action of the silymarin against NDEA administration during liver cancer progression. These findings suggest that silymarin suppresses NDEA induced hepatocarcinogenesis by modulating the antioxidant defense status of the animals.     

Effects of pycnogenol treatment on oxidative stress in streptozotocin-induced diabetic rats

Free radicals and oxidative stress have been implicated in the etiology of diabetes and its complications. This in vivo study has examined whether subacute administration of pycnogenol, a French pine bark extract containing procyanidins that have strong antioxidant potential, alters biomarkers of oxidative stress in normal and diabetic rats. Diabetes was induced in female Sprague-Dawley rats by a single injection of streptozotocin (90 mg/kg body weight, ip), resulting (after 30 days) in subnormal body weight, increased serum glucose concentrations, and an increase in liver weight, liver/body weight ratios, total and glycated hemoglobin, and serum aspartate aminotransferase activity. Normal and diabetic rats were treated with pycnogenol (10 mg/kg body weight/day, ip) for 14 days. Pycnogenol treatment significantly reduced blood glucose concentrations in diabetic rats. Biochemical markers for oxidative stress were assessed in the liver, kidney, and heart. Elevated hepatic catalase activity in diabetic rats was restored to normal levels after pycnogenol treatment. Additionally, diabetic rats treated with pycnogenol had significantly elevated levels of reduced glutathione and glutathione redox enzyme activities. The results demonstrate that pycnogenol alters intracellular antioxidant defense mechanisms in streptozotocin-induced diabetic rats.     

Effects of isoquinoline alkaloid berberine on lipid peroxidation,antioxidant defense system,and liver damage induced by lead acetate in rats

Objectives: Liver is considered a target organ affected by lead toxicity. Oxidative stress is among the mechanisms involved in liver damage. Here we investigated the effects of the natural alkaloid berberine on oxidative stress and hepatotoxicity induced by lead in rats.

Methods: Animals received an aqueous solution of lead acetate (500?mg Pb/l in the drinking water) and/or daily oral gavage of berberine (50?mg/kg) for 8 weeks. Rats were then weighed and used for the biochemical, molecular, and histological evaluations.

Results: Lead-induced oxidative stress, shown by increasing lipid peroxidation along with a concomitant decrease in hepatic levels of thiol groups, total antioxidant capacity, the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase, and reduced versus oxidized glutathione ratio. Berberine corrected all the disturbances in oxidative stress markers induced by lead administration. Berberine also prevented the elevated levels of enzymes (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase) and the decrease in body weight and albumin. The protective effects of berberine were comparable with silymarin. Furthermore, berberine attenuated liver damage, shown by decreased necrosis and inflammatory cell infiltration.

Discussion: Berberine represents a potential therapeutic option against lead-induced hepatotoxicity through inhibiting lipid peroxidation and enhancing antioxidant defenses.

Conclusion: Berberine exerted protective effects on lead-induced oxidative stress and hepatotoxicity in rats.     

Chemo-preventive effect of Star anise in N-nitrosodiethylamine initiated and phenobarbital promoted hepato-carcinogenesis

The generation of free radicals is a cause of many pathological conditions like diabetes mellitus, cancer, stroke, etc. Free radicals cause damage to cellular DNA and initiate carcinogenesis. Free radicals also bring about proliferation of cells via cell signaling. An inverse relationship between the consumption of vegetable diets and the risk of cancer has been established. In the present study, Star anise (Illicium verum), which is a commonly used condiment in Indian cuisine, was assessed for its anti-carcinogenic potential in N-nitrosodiethylamine (NDEA) initiated and phenobarbital (PB) promoted hepato-carcinogenesis. Rats were randomly selected for eight experimental groups. The carcinogenesis was induced by injecting the rats, with a single dose of NDEA (200 mg/kg body weight) intraperitoneally as initiator, followed by promotion with PB (0.05%) in drinking water for 14 consecutive weeks. The treatment with NDEA increased liver weight, while Star anise (Star) treatment reduced the liver weight of rats. The treatment with Star throughout for 20 weeks or during the promotion stage (6-20 weeks) significantly reduced the nodule incidence and nodule multiplicity in the rats, while the treatment with Star at the initiation phase (first 4 weeks) only could not reduce these parameters. The treatment with Star for 20 consecutive weeks significantly reduced the nodule size and nodule volume. The treatment with Star throughout as well as at the promotion stage lowered the lipid peroxidation (LPO) in liver and erythrocytes, while the LPO was not lowered, when Star was administered during initiation stage only. The treatment with Star restored the liver and erythrocyte super-oxide dismutase (SOD) activities to normal in the carcinogenesis-induced rats. The liver catalase (CAT) activity increased in all the treated groups. The erythrocyte CAT activity increased in the rats treated with Star during initiation and promotion stage only. The liver glutathione (GSH) level increased significantly in the groups treated with Star. The erythrocyte GSH level was lowered in the rats treated with NDEA and PB, however, Star treatment helped in increasing the erythrocyte GSH level to some extent. The liver and erythrocyte glutathione-S-transferase (GST) activity increased in all the groups treated with NDEA and PB. The treatment with Star decreased GST level significantly. These results indicate that the treatment with Star reduces the tumor burden, lowers oxidative stress and increases the level of phase II enzymes, which may contribute to its anti-carcinogenic potential.     

Estrogen administration, postexercise tissue oxidative stress and vitamin C status in male rats

Estrogen can putatively act as an antioxidant and protect tissues from exercise-induced oxidative stress. To test the in vivo efficacy of estrogen, the effects of 2 weeks of daily estrogen (40 microg x kg(-1) body weight beta-estradiol 3-benzoate) injection on indices of immediate postexercise oxidative stress and antioxidant status were determined in adult male rats, with and without 8 weeks of prior dietary vitamin E deprivation. The treadmill running protocol (60 min at 21 m x min(-1), 12% grade) induced significant oxidative stress as indicated by muscle glutathione status. Estrogen administration had little effect on postexercise tissue glutathione status, superoxide dismutase and glutathione peroxidase activity, and vitamin E levels. Estrogen administration induced significant reductions in muscle, liver, and heart vitamin C concentrations following exercise, as well as in unexercised male rats. Tissue vitamin C loss was not directly mediated through liver glycogen or glutathione status. Thus, estrogen administration generally did not appear to influence postexercise tissue indices of oxidative stress or antioxidant status and may have contributed to a decline in overall antioxidant protection by inducing losses in tissue vitamin C content.     

The anti-fatty liver effects of garlic oil on acute ethanol-exposed mice

The protective effects of single dose of garlic oil (GO) on acute ethanol-induced fatty liver were investigated. Mice were treated with ethanol (4.8 g/kg bw) to induce acute fatty liver. The liver index, the serum and hepatic triglyceride (TG) levels and the histological changes were examined to evaluate the protective effects. Hepatic malondialdehyde (MDA), glutathione (GSH) levels and superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST) activities were determined for the antioxidant capacity assay. Acute ethanol exposure resulted in the enlargement of the liver index and the increase of the serum and hepatic TG levels (P<0.01), which were dramatically attenuated by GO pretreatment in a dose-dependent manner (P<0.01). GO treatment (simultaneously with ethanol exposure) exhibited similar effects to those of pretreatment, while no obviously protective effects were displayed when it was used at 2h after ethanol intake. Histological changes were paralleled to these indices. Beside this, GO dramatically prolonged the drunken time and shortened the waking time, and these effects were superior to those of silymarin and tea polyphenol. In addition, GO dose-dependently suppressed the elevation of MDA levels, restored the GSH levels and enhanced the SOD, GR and GST activities. Compared with the ethanol group, the MDA levels decreased by 14.2% (P<0.05), 29.9% and 32.8% (P<0.01) in GO groups 50, 100 and 200 mg/kg, respectively. The GST activity increased by 9.97%, 19.94% (P<0.05) and 42.12% (P<0.01) of the ethanol group in GO groups 50, 100 and 200 mg/kg, respectively, while the GR activity increased by 28.57% (P<0.05), 37.97% (P<0.01), 50.45% (P<0.01) of the ethanol group in GO groups 50, 100 and 200 mg/kg, respectively. These data indicated that single dose of GO possessed ability to prevent acute ethanol-induced fatty liver, but may lose its capacity when used after ethanol exposure. The protective effects should be associated with its antioxidative activities.