Hepatic Glutathione S-transferase Activity Research Articles

Suppression of 7,12-dimethylbenz[ a]anthracene-induced mammary carcinogenesis by pre-initiation treatment of rats with β-naphthoflavone coincides with decreased levels of the carcinogen-derived DNA adducts in the mammary gland

Background: Mechanisms underlying prevention by β-naphthoflavone (β-NF) of mammary carcinogenesis initiated with 7,12-dimethylbenz[ a]anthracene (DMBA) in the rat were elucidated. Methods and results: Treatment of female Sprague–Dawley rats with β-NF at 40 mg/kg b.wt. for 4 days by oral gavage in corn oil before a single oral dose of DMBA (112 mg/kg b.wt.) suppressed mammary gland carcinogenesis as shown by an increase in the median latent period from 10 to 24 weeks and a 60% decrease in the multiplicity of mammary adenocarcinomas. In contrast, a 20-day treatment with β-NF starting 3 weeks after DMBA had no significant effects on mammary tumorigenesis. The activities of phase I and phase II enzymes were examined in the liver and mammary gland 24 h after treatment of rats with β-NF, DMBA, or β-NF followed by DMBA as in the first bioassay. Treatment with either β-NF or DMBA increased the hepatic activities of cytochrome P450 (CYP)1A1, 1A2, and 2B1/2, and glutathione S-transferase, and the mammary activity of CYP1A1. The activity of mammary CYP2B1/2 induced by DMBA was decreased by β-NF. In the liver, the increase of UDP-glucuronosyl transferase (GT) activity in rats treated with β-NF and DMBA was 2.3-fold greater than in rats treated with DMBA alone. Thus, treatment with β-NF likely increased the rate of glucuronidation of DMBA dihydrodiols leading to carcinogen detoxification. The levels of the DMBA adducts determined by 32P-postlabeling of the mammary gland DNA were decreased in the β-NF-pretreated rats. Conclusion: The β-NF-induced increase in the hepatic UDP-GT activity and decrease in the mammary DNA-DMBA adducts occurred under the same treatment regimen that led to suppression of DMBA-induced mammary carcinogenesis.

Phase I and II liver enzyme activities in juvenile alligators ( Alligator mississippiensis) collected from three sites in the Kissimmee–Everglades drainage, Florida (USA)

We examined CYP1A (measured using hepatic EROD and MROD activities) and glutathione-S-transferase (GST) activities in juvenile alligators ( Alligator mississippiensis) collected from three sites with varying contamination in the Kissimmee–Everglades drainage in south Florida. We hypothesized that contaminants present in areas with intermediate or higher contaminant concentrations would alter hepatic enzyme activities in juvenile alligators from those sites when compared to hepatic enzyme activity in animals from the area with the least contamination. EROD activity was found to be higher in animals from the site with lower reported levels of contamination relative to those from the site with the highest reported contamination suggesting an inhibition of CYP1A expression or activity. No differences among animals from the three sites were observed for hepatic MROD and GST activities. A significant negative relationship between EROD, MROD, and GST activities and body size was exhibited in alligators from the site with the lowest contamination. No relationship between body size and hepatic enzyme activity was found in animals from the sites with intermediate and higher contamination, suggesting that contaminants present at these sites act to alter this relationship. No correlation was observed in this study between plasma steroid concentrations (estradiol-17β or testosterone) and hepatic EROD, MROD, or GST activities.

Effects of four chlorobenzenes on serum sex steroids and hepatic microsome enzyme activities in crucian carp, Carassius auratus

Four chlorobenzenes (chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, p-chloro-methylbenzene) were administrated to the crucian carps ( Carassius auratus) by peritoneal injections in the laboratory for 30 days. Serum testosterone and 17β-estradiol concentrations were detected using radioimmunology assay (RIA), and the activities of two hepatic microsome enzymes, glutathione s-transferase (GST) and UDP-glucuronosyltransferase (UDPGT), were measured using the modified methods as described by Habig and Owens. Results showed that the four chlorobenzenes caused significant increases in serum testosterone concentration in the crucian carps ( P<0.05) compared to the controls, but they caused no significant effect on 17β-estradiol level. All test chemicals caused a change in hepatic GST activity in crucian carps, with significant increases in enzyme activity ( P<0.05). Chlorobenzene, 1,3-dichlorobenzene and p-chloro-methylbenzene resulted in a marked inhibition to UDPGT activity in crucian carp ( P<0.05) except 1,4-dichlorobenzene. The changes in hepatic microsome enzyme activities may have resulted in the alterations of serum sex steroids levels in the crucian carps. The results indicated that these four chlorobenzenes may result in the changes of endocrine functions and may affect the reproductive success of this and other species.

Papaverine, an opium alkaloid influences hepatic and pulmonary glutathione S-transferase activity and glutathione content in rats.

The present study evaluates the effect of oral administration of papaverine at differential dosing regimens (100 mg/kg bw and 200 mg/kg bw) on the hepatic and pulmonary glutathione S-transferase (GST) activity and glutathione content (GSH) in male Wistar rats. Papaverine treatment caused a pronounced increase in GST activity and GSH content at the higher dosing level in the rat liver and lung. We conclude that papaverine, can possibly act as a chemopreventive agent against chemical carcinogenesis.

Chemopreventive potential of Azadirachta indica (Neem) leaf extract in murine carcinogenesis model systems

Numerous laboratory studies reveal that various naturally occurring dietary substances can modify the patho-physiological process of various metabolic disorders and can be an effective preventive strategy for various diseases, including cancer. Indian Neem tree, Azadirachta indica A. Juss. (family: Meliaceae), contains at least 35 biologically active principles and is widely grown all over the tropics. The effect of two different doses (250 and 500 mg per kilogram body weight) of 80% ethanolic extract of the leaves of Azadirachta indica were examined on drug metabolizing Phase-I and Phase-II enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase, and lipid peroxidation in the liver of 7-week-old Swiss albino mice. Also anticarcinogenic potential of Azadirachta indica leaf extract was studied adopting protocol of benzo(a)pyrene-induced fore-stomach and 7,12-dimethyl benz(a)anthracene (DMBA)-induced skin papillomagenesis. Our primary findings reveal its potential to induce only the Phase-II enzyme activity associated mainly with carcinogen detoxification in liver of mice. The hepatic glutathione S-transferase ( P<0.005) and DT-diaphorase specific activities ( P<0.01) were elevated above basal level. With reference to antioxidant enzymes the investigated doses were effective in increasing the hepatic glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT) activities significantly (from P<0.005 to P<0.001). Reduced glutathione measured as non-protein sulphydryl was found to be significantly elevated in liver ( P<0.005) and in extrahepatic organs (from P<0.005 to P<0.001) examined in our study. Glutathione S-transferase (GST) and DT-diaphorase (DTD) showed a dose-dependent increase in extrahepatic organs. Chemopreventive response was measured by the average number of papillomas per mouse, as well as percentage of tumor-bearing animals. There was a significant inhibition of tumor burden, in both the tumor model system studied (from P<0.005 to P<0.001). Tumor incidence was also reduced by both the doses of Azadirachta indica extract.

Effect of microcystin-LR on protein phosphatase activity in fed and fasted juvenile goldfish Carassius auratus L.

Fed and fasted juvenile goldfish Carassius auratus (30 g body weight) were injected intraperitoneally (i.p.) with microcystin-LR (MC-LR) (125 μg/kg body weight) to determine the effect of alimentary status on the hepatic toxicity of MC-LR. The toxin accumulation pattern was similar in both fed and fasted treatments. MC-LR accumulated during the first 48 h post-injection and decreased significantly between 48 and 96 h. MC-LR accumulation induced a decrease in hepatic protein phosphatase activity and glycogen content. Fasted individuals were more severely and more rapidly affected than fed ones. Both indicators were significantly altered after 6 h of fasted treatment. In particular, protein phosphatase activity was totally inhibited after 6 h in the fasted treatment but only lowered and not totally suppressed in the fed one. In both treatments, the recovery of enzyme activity was complete after 96 h. On the other hand, hepatic glutathione concentration and glutathione S-transferase activity were not significantly affected.

1alpha, 25-dihydroxyvitamin D3 prevents DNA damage and restores antioxidant enzymes in rat hepatocarcinogenesis induced by diethylnitrosamine and promoted by phenobarbital.

To investigate the chemopreventive effects of 1alpha, 25-dihydroxyvitamin D(3) in diethylnitrosamine induced, phenobarbital promoted rat hepatocarcinogenesis. The rats were randomly divided into 6 different groups (A-F). Groups A, C and E rats received a single intraperitoneal (i.p.) injection of diethylnitrosamine (DEN) at a dose of 200 mg/kg body mass in 9 g/L NaCl solution at 4 wk of age, while group B served as normal vehicle control received normal saline once. After a brief recovery of 2 wk, all the DEN treated rats were given phenobarbital (PB) at 0.5 g/L daily in the basal diet till wk 20. Group A was DEN control. Treatment of 1alpha, 25-(OH)2D3 in group C was started 4 wk prior to DEN injection and continued thereafter till wk 20 at a dose of 0.3 microg/100 microL propylene glycol per one single dose (os) twice a week. Group E received the treatment of 1alpha, 25-(OH)2D3 at the same dose mentioned as above for 15 wk. The rats in group D and F received 1alpha, 25-(OH)2D3 alone as in group C without DEN injection. The comet assay showed statistically higher mean values for length to width ratios (L: W) of DNA mass and tailed cells (P<0.01; P<0.01 respectively) in DEN treated rats as compared to their normal controls. Continuous supplementation of 1alpha, 25-dihydroxyvitaminD2 showed a significant (P<0.01) decrease in L:W ratio of DNA mass tailed cells. Furthermore, 1alpha, 25-(OH)2D3 supplementations elevated the super oxide dismutase (SOD) activity, hepatic malondialdehyde (MDA) level, reduced glutathione (GSH) and glutathione S-transferase (GST) activity (P<0.01, P<0.05, P<0.05 and P<0.05 respectively). As an endpoint marker histological changes were observed to establish the chemopreventive effects of 1alpha, 25-dihydroxyvitaminD2. Supplementations of 1alpha, 25-(OH)2D3 has a marked protection against hepatic nodulogenesis, antioxidant enzymes and DNA damages in DEN induced rat hepatocarcinogenesis promoted by phenobarbital.

Chemomodulatory efficacy of basil leaf (Ocimum basilicum) on drug metabolizing and antioxidant enzymes, and on carcinogen-induced skin and forestomach papillomagenesis.

Basil or sweet basil (Ocimum basilicum) is cultivated throughout India and is known for its medicinal value. The effects of doses of 200 and 400 mg/kg body weight of hydroalcoholic extract (80% ethanol, 20% water) of the fresh leaves of Ocimum basilicum on xenobiotic metabolizing Phase I and Phase II enzymes, antioxidant enzymes, Glutathione content, Lactate dehydrogenase and lipid peroxidation in the liver of 8-9 weeks old Swiss albino mice were examined. Furthermore, the anticarcinogenic potential of basil leaf extract was studied, using the model of Benzo(a)pyrene-induced forestomach and 7,12 dimethyl benz(a)anthracene (DMBA)-initiated skin papillomagenesis. The hepatic glutathione S-transferase and DT-diaphorase specific activities were elevated above basal level by basil leaf treatment (from p < 0.005 to p < 0.001). Basil leaf extract was very effective in elevating antioxidant enzyme response by increasing significantly the hepatic glutathione reductase (GR) (p < 0.005), superoxide dismutase (SOD) (p < 0.05), and catalase activities (p < 0.005). Reduced glutathione (GSH), the major intracellular antioxidant, showed a significant elevation in the liver (p < 0.005) and also in all the extrahepatic organs (from p < 0.05 to p < 0.005). In the forestomach, kidney and lung, glutathione S-transferase and DT-diaphorase levels were augmented significantly, varying from p < 0.01 to p < 0.001. There were significant decreases in lipid peroxidation and lactate dehydrogenase activity. Chemopreventive response was evident from the reduced tumor burden (the average number of papillomas/mouse, p < 0.005 to p < 0.001), as well as from the reduced percentage of tumor bearing-animals. Basil leaf, as deduced from the results, augmented mainly the Phase II enzyme activity that is associated with detoxification of xenobiotics, while inhibiting the Phase I enzyme activity. There was an induction in antioxidant level that correlates with the significant reduction of lipid peroxidation and lactate dehydrogenase formation. Moreover, Basil leaf extract was highly effective in inhibiting carcinogen-induced tumor incidence in both the tumor models at peri-initiational level.

Antioxidant responses to benzo[ a]pyrene and Aroclor 1254 exposure in the green-lipped mussel, Perna viridis

In this study, the green-lipped mussel, Perna viridis (L.), was exposed to two concentrations of benzo[ a]pyrene (B[ a]P) (0.3 μg l −1; 3 μg l −1) and two concentrations of Aroclor 1254 (0.5 μg l −1; 5 μg l −1). In addition, a mixture of the contaminants was used (0.3 μg l −1 B[ a]P+0.5 μg l −1 Aroclor 1254; 3 μg l −1 B[ a]P+5 μg l −1 Aroclor 1254). All concentrations were nominal. A suite of enzymes [glutathione S transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR)], glutathione (GSH) level and lipid peroxidation (LPO) in the mussel gill and hepatopancreas were monitored over 18 days. CAT and GSH in gill tissue were positively correlated with concentration of Aroclor 1254. Activity of hepatic GST and SOD was significantly related to body burden of Aroclor 1254. LPO, GR and GPx in gill and hepatopancreas and hepatic GST were positively correlated with B[ a]P concentration. The results indicate the importance of using biomarkers specific to the type of contaminant(s) that are likely to be present. Controlled laboratory experiments, such as this study, are useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

Grapefruit juice intake does not enhance but rather protects against aflatoxin B1-induced liver DNA damage through a reduction in hepatic CYP3A activity.

Influence of grapefruit juice intake on aflatoxin B1 (AFB1)-induced liver DNA damage was examined using a Comet assay in F344 rats given 5 mg/kg AFB1 by gavage. Rats allowed free access to grapefruit juice for 5 days prior to AFB1 administration resulted in clearly reduced DNA damage in liver, to 65% of the level in rats that did not receive grapefruit juice. Furthermore, rats treated with grapefruit juice extract (100 mg/kg per os) for 5 days prior to AFB1 treatment also reduced the DNA damage to 74% of the level in rats that did not receive grapefruit juice. No significant differences in the portal blood and liver concentrations of AFB1 were observed between grapefruit juice intake rats and the controls. In an Ames assay with AFB1 using Salmonella typhimurium TA98, lower numbers of revertant colonies were detected with hepatic microsomes prepared from rats administered grapefruit juice, compared with those from control rats. Microsomal testosterone 6beta-hydroxylation was also lower with rats given grapefruit juice than with control rats. Immunoblot analyses showed a significant decrease in hepatic CYP3A content, but not CYP1A and CYP2C content, in microsomes of grapefruit juice-treated rats than in non-treated rats. No significant difference in hepatic glutathione S-transferase (GST) activity and glutathione content was observed in the two groups. GSTA5 protein was not detected in hepatic cytosol of the two groups. In microsomal systems, grapefruit juice extract inhibited AFB1-induced mutagenesis in the presence of a microsomal activation system from livers of humans as well as rats. These results suggest that grapefruit juice intake suppresses AFB1-induced liver DNA damage through inactivation of the metabolic activation potency for AFB1 in rat liver.

Metabolic interactions between low doses of benzo[ a]pyrene and tributyltin in arctic charr ( salvelinus alpinus): a long-term in vivo study

We have previously reported that short-term, single exposure to a high dose of tributyltin (TBT), a widely used antifouling biocide, inhibited both the in vivo metabolism and metabolic activation of the carcinogenic polycyclic aromatic hydrocarbon benzo[ a]pyrene (B aP) in fish; (B aP), in turn, stimulated TBT metabolism. Here, we provide further mechanistic evidence of mutual metabolic interactions between BaP and TBT in response to long-term, repeated exposures to low doses. Juvenile Arctic charr ( Salvelinus alpinus) received 10 separate ip injections (a single injection every 6 days) of BaP (3 mg/kg), TBT (0.3 mg/kg), or both in combination; control fish received corn oil vehicle only. Two days after the 2 nd (Day 8), 6 th (Day 32), and 10 th dose (Day 56), blood, bile, and liver samples were collected and analyzed for a suite of biomarkers. HPLC/fluorescence analysis indicated that TBT cotreatment inhibited the formation of (+)- anti-BaP diol-epoxide adducts with plasma albumin (53%, Day 8), hepatic DNA (27%, Day 32), or both albumin and globin (50 and 58%, Day 56) compared to BaP alone. This antagonistic interaction was associated with a time-dependent modulation (inhibition at Day 8, enhancement at Day 32) of both cytochrome P450 (P450)1A-mediated ethoxyresorufin O-deethylase (EROD) activity and biliary BaP metabolite formation. TBT cotreatment also inhibited (39%) the BaP-mediated induction of hepatic glutathione S-transferase (GST) activity observed at Day 8. Treatment with TBT alone increased EROD activity (60%) at Day 32, but decreased both GST activity (70 and 37%) and glutathione content (24% and 16%) at Days 32 and 56, respectively. GC/MS analysis revealed that, at Day 56, BaP cotreatment increased (200%) the levels of biliary butyltin compounds, including mono- and dibutyltin metabolites. This potentiative interaction was associated with a protective effect of BaP cotreatment against the TBT-mediated decreases in GST activity and glutathione content. The current results demonstrate that, whereas TBT inhibited BaP bioactivation via a time-dependent modulation of P4501A induction, BaP stimulated the Phase II metabolism of TBT and/or its biliary excretion. The mutual metabolic interactions between these two widespread aquatic pollutants reinforce the need for long-term in vivo interactive studies at low doses.

Evaluation of impact of PAH on a tropical fish, Oreochromis mossambicus using multiple biomarkers

Treatment of the widely occurring tropical cichlid, Oreochromis mossambicus with a pure polycyclic aromatic hydrocarbon (PAH), phenanthrene, induced a concentration-dependant formation of the enzyme, 7-ethoxyresorufin- O-deethylase (EROD). Concomittant increase (65–669%) in the activity of sorbitol dehydrogenase in the serum (SSDH) occurring with EROD induction denoted liver cell damage, which was more severe in fish exposed to lower concentrations (0.4–4 μg g −1) of the chemical. In O. mossambicus exposed to 25% refinery effluent liver damage associated with cell death was indicated by the twin analyses of SSDH and liver somatic index. Cell injury appeared to have occurred at low PAH concentrations due to inadequately induced phase II-related detoxification of metabolites. This was indicated by the nearly 33% higher activity of hepatic glutathione S-transferase (GST) in fish exposed to higher PAH concentrations as compared to low-exposure animals. Tilapia such as O. mossambicus were found to be eminently suited for biomonitoring in tropical coastal waters. A combination of EROD and serum sorbitol dehydrogenase activity measurements serves as an excellent tool for biomonitoring sublethal effects of PAH pollution in fish.

Effects of Commonly Consumed Fruit Juices and Carbohydrates on Redox Status and Anticancer Biomarkers in Female Rats

Administration of apple juice, black currant juice, or a 1:1 combination of the two juices significantly decreased the level of the lipid peroxidation biomarker malondialdehyde in plasma of female rats, whereas the protein oxidation biomarker 2-amino-adipic semialdehyde, was significantly increased following administration of orange juice, black currant juice, or the 1:1 combination of apple and black currant juice. A significant increase in 2-amino-adipic semialdehyde was also observed in control rats given sucrose, fructose, and glucose in the drinking water at concentrations approximating the average carbohydrate levels in the employed fruit juices. None of the fruit juices were found to affect the activities of antioxidant enzymes in red blood cells or hepatic glutathione S-transferase. Hepatic quinone reductase activity, on the other hand, was significantly increased by grapefruit juice, apple juice, and black currant juice. The total daily intake of a selected subset of flavonoid aglycones ranged from 0.2 to 4.3 mg, and quercetin was found to be a minor constituent of all the juices investigated. In a parallel study, rats were fed quercetin at doses ranging from 0.001 to 10 g/kg of diet. However, no effects were observed on hepatic glutathione S-transferase or quinone reductase activities, plasma redox status, or the activity of red blood cell antioxidant enzymes. Overall, the results of the present study suggest that commonly consumed fruit juices can alter lipid and protein oxidation biomarkers in the blood as well as hepatic quinone reductase activity, and that quercetin may not be the major active principle. The observation that natural carbohydrates are capable of mediating oxidative stress in vivo warrants further studies due to the central role refined and unrefined carbohydrates play in human nutrition.

Ecotoxicological Risks Associated with Land Treatment of Petrochemical Wastes. II. Effects on Hepatic Phase I and Phase II Detoxification Enzymes in Cotton Rats

The purpose of this study was to evaluate possible exposure and resultant hepatic effects of petrochemical waste on cotton rats (Sigmodon hispidus) living on landfarmed sites. Male and female cotton rats were collected in summer, fall, and winter from four landfarm sites and four ecologically similar reference sites. Hepatic methoxyresorufin O-deethylase (MROD) activity was significantly induced in male and female rats collected from landfarms compared to rats collected from reference sites. In contrast, changes in ethoxyresorufin O-deethylase (EROD) activity were inconsistent due to season, sex, and treatment variation. A significant decrease in EROD and MROD activity was found in cotton rats held for 48 h prior to sacrifice compared to rats euthanized on the day of capture. These results indicate that when using hepatic EROD and MROD activities as biochemical markers of exposure to aryl hydrocarbon receptor agonists, animals should be euthanized as quickly as possible after capture. The cotton rats collected from one landfarm unit exhibited a pattern of consistent elevation of EROD, MROD, and pentoxyresorufin O-deethylase (PROD) activity. This unit also had a pattern of elevated CYP1A2 protein expression determined by Western blotting. There were no consistent alterations from contaminant exposure on hepatic glutathione S-transferase (GST) activity, glutathione levels, or CYP1A1 protein. Hepatic EROD and MROD activities varied considerably between seasons and sex of rats. In conclusion, consistent induction of hepatic EROD and MROD activities in cotton rats was found in three out of four sampled landfarm sites compared to the rats collected from the reference sites, indicating exposure to contaminants--likely polyaromatic hydrocarbons.

Modulatory effect of henna leaf (Lawsonia inermis) on drug metabolising phase I and phase II enzymes, antioxidant enzymes, lipid peroxidation and chemically induced skin and forestomach papillomagenesis in mice.

Henna leaf (Lawsonia inermis), commonly known as Mehndi is cultivated throughout India and is a very popular natural dye to color hand and hair. It is an integral part of indigenous culture, and is also known for its medicinal value. The effect of 200 and 400 mg/kg body weight of 80% ethanolic extract of the fresh leaves of Lawsonia inermis were examined on drug metabolizing phase-I and phase-II enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase and lipid peroxidation in the liver of 7 weeks old Swiss albino mice. Also anticarcinogenic potential of Henna leaf extract was studied adopting the protocol of benzo(a)pyrene induced forestomach and 7,12 dimethylbenz(a)anthracene (DMBA)-initiated and croton oil-promoted skin papillomagenesis. Our primary findings reveal the 'duel-acting' nature of henna leaf as deduced from its potential to induce only the phase-II enzyme activity, associated mainly with carcinogen detoxification in liver of mice and inhibit the phase I enzyme activities. The hepatic glutathione S-transferase and DT-diaphorase specific activities were elevated above basal (p < 0.005) level by Lawsonia inermis extract treatment. With reference to antioxidant enzymes the investigated doses were effective in increasing the hepatic glutathione reductase (GR), superoxide dismutase (SOD) and catalase activities significantly (from p < 0.05 to p < 0.005) at both the dose levels. Reduced glutathione (GSH) measured as non-protein sulphydryl was found to be significantly elevated in liver (p < 0.005) and in all the extrahepatic organs studied (from p < 0.05 to p < 0.005). Among the extrahepatic organs examined (forestomach, kidney and lung) glutathione S-transferase and DT-diaphorase level were increased in a dose independent manner (from p < 0.05 to p < 0.005). Chemopreventive response was measured by the average number of papillomas per mouse (tumor burden) as well as percentage of tumor bearing animals and tumor multiplicity. There was a significant inhibition of tumor burden in both the tumor model systems studied (from p < 0.01 to p < 0.001). Tumor incidence was also reduced by both the doses used in our experiment in both the model systems.

Effects of three fungicides alone and in combination on glutathione S-transferase activity (GST) and cytochrome P-450 (CYP 1A1) in the liver and gill of brown trout (Salmo trutta)

In order to evaluate the gill glutathione S-transferase (GST) activity as a biomarker of effect of fungicide exposure in juvenile brown trout (Salmo trutta), the fungicides propiconazole {(R,S)-1-[2-(2,4-diclophenyl)-4-propyl-1,3-dioolan-2-ylmetyl]-1H-1,2,4-triazole} and fenpropimorph {(±)-cis-4-[3-(4-tert-butylphenyl)-2-metyl propyl]-2,6 dimetylmorfolinc} were administrated in the water separately and together in a static system (80 μg/l for each pesticide) for 5 days. The combined fungicides gave a significant decrease in gill GST activity towards 1-chloro-2,4-dinitrobenzene (CDNB), whilst hepatic GST-activity was not significantly changed. Furthermore, continuous exposure to 540 ug/l thiabendazole{ 2-(thiazol-4′-yl)benzimidazole} in a flow-through system for 4 days significantly increased the gill glutathione S-transferase (GST) activity towards CDNB, whilst hepatic GST and cytochrome P450 (CYP 1A) activities were not increased by the treatment.

Studies of Masculinization, Detoxification, and Oxidative Stress Responses in Guppies (Poecilia reticulata) Exposed to Effluent from a Pulp Mill

Potential masculinization, detoxification, and oxidative stress responses were assessed in domesticated female guppies (Poecilia reticulata) exposed for 42 days to diluted effluent from a modern Swedish kraft pulp mill or a model androgen. Methyltestosterone induced male-like coloration and transformation of the anal fin into a gonopodium-like structure. The effluent did not induce any apparent changes of the anal fin morphology; however, the exposed guppies became more colored than control fish, which could be an androgenic response. A better understanding of the physiological mechanisms involved in these responses would be required for a full evaluation. Both primary effluent and effluent which had undergone activated sludge treatment caused a moderate but significant induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity. However, the general toxicity of both effluents was low, as mortality was negligible even at 25% dilutions. There was a continuous production of offspring in all groups (47–62% female fry), except by methyltestosterone-treated females, which did not reproduce. There were no indications that either effluent caused oxidative stress since hepatic glutathione reductase, glutathione S-transferase and DT-diaphorase activities remained unchanged compared with controls.

Comparison of the Bioactivity of Two Glucoraphanin Hydrolysis Products Found in Broccoli, Sulforaphane and Sulforaphane Nitrile

Epidemiological and laboratory studies suggest that dietary broccoli may prevent or delay a variety of cancers. Broccoli and other crucifers contain a relatively unique family of secondary metabolites called glucosinolates. Glucoraphanin, the major glucosinolate in broccoli, is hydrolyzed by an endogenous plant myrosinase to form either the potent anticarcinogen sulforaphane (SF) or sulforaphane nitrile (SF nitrile). The bioactivities of SF and SF nitrile were compared in rats and in mouse hepatoma cells. Male, 4-week-old, Fischer 344 rats were administered SF or SF nitrile (200, 500, or 1000 micromol/kg) by gavage daily for 5 days. Hepatic, colonic mucosal, and pancreatic quinone reductase and glutathione S-transferase activities were induced by high doses of SF, but not by SF nitrile. When Hepa 1c1c7 cells were exposed to increasing levels of each compound for 24 h, quinone reductase showed a 3-fold maximal induction over control at 2.5 microM SF and a 3.5-fold maximal induction over control at 2000 microM SF nitrile, the highest concentration tested. These results demonstrate that SF nitrile is substantially less potent than SF as an inducing agent of phase II detoxification enzymes. Therefore, glucoraphanin hydrolysis directed toward the production of SF rather than SF nitrile could increase the potential chemoprotective effects of broccoli.

Effect of coriander seeds on hexachlorocyclohexane induced lipid peroxidation in rat liver

The effect of prefeeding of coriander seed powder (CSP) at 10% level on hexachlorocyclohexane (HCH) induced oxidative stress in rat liver was studied. The prefeeding of rats with CSP was found to reduce the HCH-induced rise in conjugated dienes, hydroperoxide and malondialdehyde (MDA) contents in liver. The intra peritonial injection of HCH reduced hepatic superoxide dismutase (SOD), catalase, glutathione S-transferase (GS-t), glucose-6-phosphate dehydrogenase (G-6-PDH) and glutathione reductase (GSSGR) activities in liver, where as the hepatic glutathione peroxidase (GSH-Px) and kidney γ-glutamyltranspeptidase (GGT) activities were elevated. The prefeeding of CSP per se increased hepatic SOD, catalase, GS-t, G-6-PDH and GSSGR activities as well as in CSP prefed and then HCH-administered rats. The work shows the modulation of hepatic antioxidant system as a result of the prefeeding of CSP, which were otherwise reduced by HCH injection. The results reported here elicit the antioxidative effect of coriander seeds against HCH-induced formation of free radicals in rat liver.

Alterations in hepatic detoxifying enzymes induced by new organophosphorus insecticides following subchronic exposure in rats.

The present study examined the structure-toxicity relationship of two novel phosphorothionates, a methyl ester (RPR-II) and an ethyl ester (RPR-V), with regard to their interaction with certain biochemical indices in rat. Male rats were treated orally with 10% (low), 20% (medium) and 30% (high) doses of the two compounds (14, 28 and 42 microg kg(-1) day (-1) of RPR-II and 33, 66 and 99 microg kg(-1) day(-1) of RPR-V) daily for 90 days. The activity of hepatic glutathione S-transferase (GST) and UDP-glucuronyl transferase (UDPGT) and the level of glutathione (GSH) were estimated at 0, 45 and 90 days of treatment as well as 28 days after cessation of treatment. RPR-II caused statistically significant depletion of GSH after 45 and 90 days of treatment at the high dose, whereas RPR-V depleted GSH only after 90 days at the high dose. RPR-II inhibited GST after 45 and 90 days at medium and high doses, whereas RPR-V caused inhibition of GST after 45 and 90 days only at the high dose. Significantly, UDPGT activity was increased only by the high dose of RPR-II after 90 days. However, a dose and time-dependent increase in UDPGT activity was observed at all three doses of RPR-V after 45 and 90 days. There was no modulation in any of the three indices at low doses of the two organophosphorus insecticides. The withdrawal study revealed that induced changes in hepatic parameters were reversible 28 days after cessation of treatment. The results indicated that the two insecticides had different potential to modulate hepatic GST, UDPGT and GSH due to subchronic exposure and that these metabolic alterations are quite reversible after withdrawal of treatment.