Tamarix gallica ameliorates thioacetamide-induced hepatic oxidative stress and hyperproliferative response in Wistar rats

Tamarix gallica, a hepatic stimulant and tonic, was examined for its ability to inhibit thioacetamide (TAA)-induced hepatic oxidative stress, toxicity and early tumor promotion response in male Wistar rats. TAA (6.6 mmol/kg body wt. i.p) enhanced lipid peroxidation, hydrogen peroxide content, glutathione S-transferase and xanthine oxidase with reduction in the activities of hepatic antioxidant enzymes viz., glutathione peroxidase, superoxide dismutase and caused depletion in the level of hepatic glutathione content. A marked increase in liver damage markers was also observed. TAA treatment also enhanced tumor promotion markers, ornithine decarboxylase (ODC) activity and [3H] thymidine incorporation into hepatic DNA. Pretreatment of rats orally with Tamarix gallica extract (25 and 50 mg/kg body weight) prevented TAA-promoted oxidative stress and toxicity. Prophylaxis with Tamarix gallica significantly reduced the susceptibility of the hepatic microsomal membrane for iron-ascorbate induced lipid peroxidation, H2O2 content, glutathione S-transferase and xanthine oxidase activities. There was also reversal of the elevated levels of liver marker parameters and tumor promotion markers. Our data suggests that Tamarix gallica is a potent chemopreventive agent and may suppress TAA-mediated hepatic oxidative stress, toxicity, and tumor promotion response in rats.     

Preventive effect of tannic acid on 2-acetylaminofluorene induced antioxidant level, tumor promotion and hepatotoxicity: a chemopreventive study

Tannic acid, present in almost every food derived from plants, has been widely investigated as a chemopreventive agent because, apart from its use as a food additive, pharmacological studies have demonstrated its many health-promoting properties. In this study, we show the modulatory effect of tannic acid on 2-acetylaminofluorene (2-AAF)-mediated hepatic oxidative stress and cell proliferation in rats. 2-AAF (50 mg/kg body weight) caused reduction in hepatic glutathione content and the activities of hepatic anti-oxidant enzymes and phase-II metabolizing enzymes with an enhancement of xanthine oxidase activity, lipid peroxidation and hydrogen peroxide content. 2-AAF treatment also induced serum oxaloacetate and pyruvate transaminase, lactate dehydrogenase and gamma-glutamyl transpeptidase. Treatment of rats orally with tannic acid (125 and 250 mg/kg body weight) resulted in significant recovery of hepatic glutathione content, antioxidant and phase-II metabolizing enzymes. Also, significant decreases in lipid peroxidation, xanthine oxidase, hydrogen peroxide generation and liver damage marker enzymes were observed. The antiproliferative efficacy of the tannic acid was also evaluated. The promotion parameters induced (ornithine decarboxylase activity and DNA synthesis) by 2-AAF administration in the diet with partial hepatectomy (PH) were also significantly suppressed, dose dependently, by tannic acid. Hence, we propose that tannic acid might suppress the promotion stage via inhibition of oxidative stress and polyamine biosynthetic pathway.     

Tamarix gallica ameliorates thioacetamide–induced hepatic oxidative stress and hyperproliferative response in Wistar rats

Tamarix gallica, a hepatic stimulant and tonic, was examined for its ability to inhibit thioacetamide (TAA)-induced hepatic oxidative stress, toxicity and early tumor promotion response in male Wistar rats. TAA (6.6 mmol/kg body wt. i.p) enhanced lipid peroxidation, hydrogen peroxide content, glutathione S-transferase and xanthine oxidase with reduction in the activities of hepatic antioxidant enzymes viz., glutathione peroxidase, superoxide dismutase and caused depletion in the level of hepatic glutathione content. A marked increase in liver damage markers was also observed. TAA treatment also enhanced tumor promotion markers, ornithine decarboxylase (ODC) activity and [³H] thymidine incorporation into hepatic DNA. Pretreatment of rats orally with Tamarix gallica extract (25 and 50 mg/kg body weight) prevented TAA-promoted oxidative stress and toxicity. Prophylaxis with Tamarix gallica significantly reduced the susceptibility of the hepatic microsomal membrane for iron-ascorbate induced lipid peroxidation, H₂O₂ content, glutathione S-transferase and xanthine oxidase activities. There was also reversal of the elevated levels of liver marker parameters and tumor promotion markers. Our data suggests that Tamarix gallica is a potent chemopreventive agent and may suppress TAA-mediated hepatic oxidative stress, toxicity, and tumor promotion response in rats.     

Vitamin E inhibits hepatic oxidative stress, toxicity and hyperproliferation in rats treated with the renal carcinogen ferric nitrilotriacetate

Ferric nitrilotriacetate (Fe-NTA) is a potent renal and hepatic tumor promoter, which acts through a mechanism involving oxidative stress. Fe-NTA when injected intraperitoneally into rats induces hepatic ornithine decarboxylase activity as well as hepatic DNA synthesis. Vitamin E is a well-known, lipid-soluble and chain-breaking antioxidant which protects cell membranes from peroxidative damage. In this study, we investigated the protective effect of vitamin E, a major fat-soluble antioxidant, against Fe-NTA-mediated hepatic oxidative stress, toxicity and hyperproliferation in Wistar rats. Animals were treated with two different doses of vitamin E for 1 week prior to Fe-NTA treatment. Vitamin E at a higher dose of 2.0 mg/animal/day showed significant reduction in Fe-NTA-induced hepatic ornithine decarboxylase activity, DNA synthesis, microsomal lipid peroxidation and hydrogen peroxide generation. Fe-NTA treatment alone caused depletion of glutathione, glutathione metabolizing and antioxidant enzymes in rat liver, whereas pretreatment of animals with vitamin E reversed these changes in a dose-dependent manner. Taken together, our results suggest that vitamin E may afford substantial protection against the damage caused by Fe-NTA exposure and can serve as a potent preventive agent to suppress oxidant-induced tissue injury.     

Liver necrosis and fulminant hepatic failure in rats: protection by oxyanionic form of tungsten

The hepatic lesion produced as a result of oxidative stress is of wide occurrence. In the present study, the effect of tungsten on liver necrosis and fulminant hepatic failure (FHF) has been studied in rats treated with various compounds known to produce oxidative stress. Supplementation of animals with sodium tungstate for 7 weeks before the induction of liver injury by chemicals including thioacetamide (TAA), carbon tetrachloride (CCl(4)), or chloroform (CHCl(3)) could protect progression of hepatic injury. Various biochemical changes associated with liver damage and oxidative stress were measured. Hepatic malondialdehyde content, endogenous tripeptide, and reduced glutathione were measured as oxidative stress markers. The activity of xanthine oxidase, which generates reactive oxygen species (ROS) as a by-product, was also determined and found to be perturbed. Tungsten supplementation to rats caused a significant decrease in lipid peroxidation and lowered the levels of the biochemical markers of hepatic lesions produced by TAA, CCl(4) (CCl(4)), or CHCl(3). Tungsten could also cause an increase in the survival rate in rats receiving lethal doses of TAA, CCl(4), or CHCl(3). The protective effect of tungsten, however, is suggested to be limited to the conditions where the hepatic lesion is reported to be due to the generation of ROS. The progression of liver injury produced by the compounds causing oxidative stress without initiating the generation of free radicals such as bromobenzene (BB), or acetaminophen (AAP), could not be inhibited by tungsten. The possible mechanism explaining the role of oxyanionic form of tungsten in free radical-induced hepatic lesions is discussed.     

Vitamin E inhibits hepatic oxidative stress,toxicity and hyperproliferation in rats treated with the renal carcinogen ferric nitrilotriacetate

Abstract

Ferric nitrilotriacetate (Fe-NTA) is a potent renal and hepatic tumor promoter, which acts through a mechanism involving oxidative stress. Fe-NTA when injected intraperitoneally into rats induces hepatic ornithine decarboxylase activity as well as hepatic DNA synthesis. Vitamin E is a well-known, lipid-soluble and chain-breaking antioxidant which protects cell membranes from peroxidative damage. In this study, we investigated the protective effect of vitamin E, a major fat-soluble antioxidant, against Fe-NTA-mediated hepatic oxidative stress, toxicity and hyperproliferation in Wistar rats. Animals were treated with two different doses of vitamin E for 1 week prior to Fe-NTA treatment. Vitamin E at a higher dose of 2.0 mg/animal/day showed significant reduction in Fe-NTA-induced hepatic ornithine decarboxylase activity, DNA synthesis, microsomal lipid peroxidation and hydrogen peroxide generation. Fe-NTA treatment alone caused depletion of glutathione, glutathione metabolizing and antioxidant enzymes in rat liver, whereas pretreatment of animals with vitamin E reversed these changes in a dose-dependent manner. Taken together, our results suggest that vitamin E may afford substantial protection against the damage caused by Fe-NTA exposure and can serve as a potent preventive agent to suppress oxidant-induced tissue injury.     

Inhibition of benzoyl peroxide and ultraviolet-B radiation induced oxidative stress and tumor promotion markers by cycloartenol in murine skin

The chemopreventive potential of cycloartenol on benzoyl peroxide and UVB radiation-induced cutaneous tumor promotion markers and oxidative stress in murine skin is assessed. Benzoyl peroxide treatment (20 mg/animal/0.2 ml acetone) and UVB radiation (0.420 J/m(2)/s) caused a decrease in the activities of cutaneous antioxidant enzymes namely, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, phase II metabolizing enzyme such as glutathione-S-transferase and quinone reductase and depletion in the level of cutaneous glutathione. There was also enhancement in cutaneous microsomal lipid peroxidation, xanthine oxidase activity, [(14)C]-ornithine decarboxylase activity and [(3)H]-thymidine incorporation into cutaneous DNA. Cycloartenol was topically applied prior to the application of benzoyl peroxide at dose levels of 0.2 mg and 0.4 mg/kg body weight in acetone, which resulted in significant inhibition of epidermal ornithine decarboxylase activity and DNA synthesis (P < 0.001). There was also significant reduction of lipid peroxidation and xanthine oxidase activity (P < 0.001). In addition, the depleted levels of glutathione, inhibited activities of antioxidant and phase II metabolizing enzymes, were also recovered to a significant level (P < 0.001). The data indicate that cycloartenol is an effective chemopreventive agent in skin carcinogenesis.     

Amelioration of D-galactosamine-induced acute liver injury in rats by dietary supplementation with betaine derived from sugar beet molasses

The effects of betaine supplementation on D-galactosamine-induced liver injury were examined in terms of hepatic and serum enzyme activities and of the levels of glutathione and betaine-derived intermediates. The rats induced with liver injury showed marked increases in serum enzyme activity, but those receiving dietary supplementation of 1% betaine showed enzyme activity levels similar to a control group without liver injury. Administration of betaine also increased both hepatic and serum glutathione levels, even following D-galactosamine injection. The activity of glutathione-related enzymes was markedly decreased following injection of D-galactosamine, but remained comparable to that of the control group in rats receiving 1% betaine. The concentrations of hepatic S-adenosyl methionine and cysteine showed similar trends to that observed for hepatic glutathione levels. These results indicate that 1% betaine has a hepatoprotective effect by increasing hepatic and serum glutathione levels along with glutathione-related enzyme activities in rats.     

Role of mammalian cytosolic molybdenum Fe-S flavin hydroxylases in hepatic injury

The study was designed to investigate the role of molybdenum iron-sulfur flavin hydroxylases in the pathogenesis of liver injuries induced by structurally and mechanistically diverse hepatotoxicants. While carbon tetrachloride (CCl4), thioacetamide (TAA) and chloroform (CHCl3) inflict liver damage by producing free radicals, acetaminophen (AAP) and bromobenzene (BB) exert their effects by severe glutathione depletion. Appropriate doses of these compounds were administered to induce liver injury in rats. The activities of the Mo-Fe-S flavin hydroxylases were measured and correlated with the biochemical markers of hepatic injury. The activity levels of the anti-oxidative enzymes and glutathione redox cycling enzymes were also determined. The treatment of rats with the hepatotoxins that inflict liver injury by generating free radicals (CCl4, TAA, CHCl3) had elevated activity levels of hepatic Mo-Fe-S flavin hydroxylases (p<0.05). Specific inhibition of these hydroxylases by their common inhibitor, sodium tungstate, suppresses biochemical and oxidative stress markers of hepatic tissue damage. On the contrary, Mo-Fe-S flavin hydroxylases did not show any change in animals receiving AAP and BB. Correspondingly, sodium tungstate could not attenuate damage in AAP and BB treated groups of rats. The study concludes that Mo-Fe-S hydroxylases contribute to the hepatic injury inflicted by free radical generating agents and does not play any role in hepatic injury produced by glutathione depleting agents. The study has implication in understanding human liver diseases caused by a variety of agents, and to investigate the efficacy of the inhibitors of Mo-Fe-S flavin hydroxylases as potential therapeutic agents.     

Thioacetamide-Induced Fulminant Hepatic Failure Induces Cerebral Mitochondrial Dysfunction by Altering the Electron Transport Chain Complexes

Fulminant hepatic failure (FHF) is an acute form of hepatic encephalopathy resulting from severe inflammatory or necrotic liver damage without any previously established liver damage. This develops as a complication due to viral infections, and drug abuse. FHF also occurs in acute disorders like Reye’s syndrome. Although the exact mechanisms in the etiology of FHF are not understood, elevated levels of brain ammonia have been consistently reported. Such increased ammonia levels are suggested to alter neurotransmission signals and impair cerebral energy metabolism due to mitochondrial dysfunctions. In the present study we have examined the role of cerebral electron transport chain complexes, including complex I, II, III IV, and pyruvate dehydrogenase in the non-synaptic mitochondria isolated from the cortex of the thioacetamide-induced FHF rats. Further, we have examined if the structure of mitochondria is altered. The results of the current study demonstrated a decrease in the activity of the complex I by 31 and 48% at 18 and 24 h respectively after the thioacetamide injection. Similarly, the activity of electron transport chain complex III was inhibited by 35 and 52% respectively, at 18 and 24 h, respectively. The complex II and complex IV, on the other hand, revealed unaltered activity. Further the activity of pyruvate dehydrogenase at 18 and 24 h after the induction of FHF was inhibited by 29 and 43%, respectively. Our results also suggest mitochondrial swelling in FHF induced rats. The inhibition of the respiratory complexes III and I and pyruvate dehydrogenase might lead to the increased production of free radical resulting in oxidative stress and cerebral energy disturbances thereby leading to mitochondrial swelling and further contributing to the pathogenesis of FHF.     

Chemomodulatory effect of Ficus racemosa extract against chemically induced renal carcinogenesis and oxidative damage response in Wistar rats

Ferric nitrilotriacetate (Fe-NTA) is a well-known renal carcinogen. In this communication, we show the chemopreventive effect of Ficus racemosa extract against Fe-NTA-induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase, gamma-glutamyl transpeptidase and hydrogen peroxide (H(2)O(2)) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. It also enhances blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity and thymidine [(3)H] incorporation into renal DNA. It also enhances DEN (N-diethylnitrosamine) initiated renal carcinogenesis by increasing the percentage incidence of tumors. Treatment of rats orally with F. racemosa extract (200 and 400 mg/kg body weight) resulted in significant decrease in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H(2)O(2) generation, blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (P<0.001) and incidence of tumors. Renal glutathione content (P<0.01), glutathione metabolizing enzymes (P<0.001) and antioxidant enzymes were also recovered to significant level (P<0.001). Thus, our data suggests that F. racemosa extract is a potent chemopreventive agent and suppresses Fe-NTA-induced renal carcinogenesis and oxidative damage response in Wistar rats.     

Glutathione metabolizing enzymes and oxidative stress in ferric nitrilotriacetate mediated hepatic injury

Summary

Glutathione (GSH) plays several important roles in the protection of cells against oxidative damage, particularly following exposure to xenobiotics. Ferric nitrilotriacetate (Fe-NTA) is a potent depletor of GSH and also enhances tissue lipid peroxidation. In this study, we show the effect of Fe-NTA treatment on hepatic GSH and some of the glutathione metabolizing enzymes, oxidant generation and liver damage. The level of hepatic GSH and the activities of glutathione reductase, glutathione S-transferase, glutathione peroxidase, and glucose 6-phosphate dehydrogenase all decrease following Fe-NTA administration. In these parameters the maximum decrease occurred at 12 h following Fe-NTA treatment. In contrast, γ-glutamyl transpeptidase was increased at this time. Not surprisingly, the increase in the activity of γ-glutamyl transpeptidase and decreases in GSH, glutathione peroxidase, glutathione reductase, glucose 6-phosphate dehydrogenase and glutathione S-transferase were found to be dependent on the dose of Fe-NTA administered. Fe-NTA administration also enhances the production of H₂O₂ and increases hepatic lipid peroxidation. Parallel to these changes, Fe-NTA enhances liver damage as evidenced by increases in serum transaminases. Once again, the liver damage is dependent on the dose of Fe-NTA and is maximal at 12 h. Pretreatment of animals with antioxidant, butylated hydroxy anisole (BHA), protects against Fe-NTA-mediated hepatotoxicity further supporting the involvement of oxidative stress in Fe-NTA-mediated hepatic damage. In aggregate, our results indicate that Fe-NTA administration eventuates in decreased hepatic GSH, a fall in the activities of glutathione metabolizing enzymes and excessive production of oxidants, all of which are involved in the cascade of events leading to iron-mediated hepatic injury.     

Fasciola hepatica: liver enzymes in rats and interaction with chemical inducers

Adult male rats were sorted into control and infected groups, the latter receiving an oral dose of 20 metacercariae of Fasciola hepatica. In Weeks 3 and 6 after infection, some rats received phenobarbital or 3-methylcholanthrene which induced drug metabolizing enzymes. The parasitic pathology was ascertained by clinical observation of the rats and at autopsy. Hepatic microsomal cytochrome P-450 content was significantly decreased in infected rats compared to untreated phenobarbital treated groups. In all infected rats, the simultaneous increase in cytosolic calcium and decrease in cytosolic glutathione corresponded to oxidative cell injury occurring in the course of fascioliasis. Both arylamine acetyltransferase (EC 2.3.1.5.) and glutathione transferase (EC 2.5.1.18) activities were decreased in all newly infected and 6 week infected groups. Fascioliasis did not alter the substrate related uridine diphosphate glucuronosyltransferase activities (EC 2.4.1.17) of any rat group.     

Changes in cerebral membrane lipid composition and fluidity during thioacetamide-induced hepatic encephalopathy

Lipids are an essential structural and functional component of cellular membranes. Changes in membrane lipid composition are known to affect the activities of many membrane-associated enzymes, endocytosis, exocytosis, membrane fusion and neurotransmitter uptake, and have been implicated in the pathophysiology of many neurodegenerative disorders. In the present study, we investigated changes in the lipid composition of membranes isolated from the cerebral cortex of rats treated with thioacetamide (TAA), a hepatotoxin that induces fulminant hepatic failure (FHF) and thereon hepatic encephalopathy (HE). HE refers to acute neuropsychiatric changes accompanying FHF. The estimation of membrane phospholipids, cholesterol and fatty acid content in cerebral cortex membranes from TAA-treated rats revealed a decrease in cholesterol, phosphatidylserine, sphingomyelin, a monounsaturated fatty acid, namely oleic acid, and the polyunsaturated fatty acids gamma-linolenic acid, decosa hexanoic acid and arachidonic acid compared with controls. Assessment of membrane fluidity with pyrene, 1,6-diphenyl-1,3,5-hexatriene and 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene revealed a decrease in the annular membrane fluidity, whereas the global fluidity was unaffected. The level of the thiobarbituric acid reactive species marker for lipid peroxidation also increased in membranes from TAA-treated rats, thereby indicating the prevalence of oxidative stress. Results from the present study demonstrate gross alterations in cerebral cortical membrane lipid composition and fluidity during TAA-induced HE, and their possible implications in the pathogenesis of this condition are also discussed.     

Induction of renal oxidative stress and cell proliferation response by ferric nitrilotriacetate (Fe-NTA): diminution by soy isoflavones

Ferric nitrilotriacetate (Fe-NTA) is a known potent nephrotoxic agent. In this communication, we report the chemopreventive effect of soy isoflavones on renal oxidative stress, toxicity and cell proliferation response in Wistar rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances gamma-glutamyl transpeptidase, renal lipid peroxidation, xanthine oxidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. Fe-NTA treatment also induced tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. A sharp elevation in the levels of blood urea nitrogen and serum creatinine has also been observed. Treatment of rats orally with soy isoflavones (5 mg/kg body weight and 10 mg/kg body weight) resulted in significant decreases in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Renal glutathione content (P < 0.01), glutathione metabolizing enzymes (P < 0.001) and antioxidant enzymes were also returned to normal levels (P < 0.001). Thus, our data suggest that soy isoflavones may be used as an effective chemopreventive agent against Fe-NTA-mediated renal oxidative stress, toxicity and cell proliferation response in Wistar rats.     

Hepatotoxicity and aging: endogenous antioxidant systems in hepatocytes from 2-, 6-, 12-, 18- and 30-month-old rats following a necrogenic dose of thioacetamide

The influence of aging on the mechanisms of liver injury and regeneration was studied in a model of hepatotoxicity induced in 2-, 6-, 12-, 18- and 30-month-old rats by a sublethal dose of thioacetamide (500 mg/kg body weight), a soft nucleophilic and hepatotoxic compound metabolized by the hepatic microsomal FAD monooxygenase system. Samples-blood and hepatocytes-were obtained at 0, 12, 24, 48, 72 and 96 h following thioacetamide intoxication. Parameters of liver injury in serum (NADPH-isocitrate dehydrogenase (ICDH) activity) indicate that the severity of injury was significantly higher in the adult groups (6 and 12 months old) when compared either with the youngest (2 months old) or oldest (18 and 30 months old) groups. Parameters related to biotransformation, such as microsomal FAD monooxygenase, followed mainly the same pattern of age-dependent changes as those observed for injury. The profile of glutathione-S-transferase activity showed an initial induction parallel to liver injury and opposite to the levels of reduced glutathione and protein -SH groups. Enzyme activities and gene expression of the systems involved in the cell endogenous antioxidant defense, such as Mn- and Cu,Zn-superoxide dismutases (SOD), catalase and glutathione peroxidase (GPX) showed significant age-dependent changes that can be summarized as follows: an increase in all enzyme activities and gene expression and a decreased ability to restore the initial activities following 96 h of thioacetamide. We conclude, first, that the gene expression and activity of the enzymes involved in the intracellular antioxidant defense system increased with aging, which can be considered a consequence of the enhanced oxidative state of the cell (decreased in GSH level); and second, that the lower and delayed response in the aged groups significantly influenced the restoration towards normal of GSH and the antioxidant enzyme activities.     

Effect of T3 treatment on glutathione redox pool and its metabolizing enzymes in mitochondrial and post-mitochondrial fractions of adult rat testes

T3 (3,3', 5-triiodo-L-thyronine; 20 microg/100 g body weight/day in 0.01 N NaOH, i.p for 1, 3 and 5 days) treatment modulated reduced (GSH) and oxidized (GSSG) glutathione contents along with the activities of its metabolizing enzymes (such as glutathione peroxidase, glutathione reductase and glutathione S-transferase) in the testis of Wistar rats. However, the magnitude and nature of changes in the above biochemical parameters in response to T3 treatment were noticed to be different between mitochondrial and post-mitochondrial fractions. This was accompanied with elevated levels of lipid hydroperoxide and ascorbic acid in the crude homogenate of testis. The level of hydrogen peroxide in the post-mitochondrial fractions of testes did not change on first day, decreased on 3rd day and increased on 5th day of the hormone treatment when compared to respective controls. Nevertheless, its content in mitochondria was significantly elevated in response to all the three durations of the hormone treatment having the highest induction on 3rd day. The changes observed in the levels of GSH and GSSG and its metabolizing enzymes in response to T3 treatment reflect an alteration in the redox state of testis, which may be a causative factor for the impairment of testicular physiology as a consequence of oxidative stress.     

Modulatory Effects of Shape Pluchea Lanceolata Against Chemically Induced Oxidative Damage, Hyperproliferation And Two-Stage Renal Carcinogenesis in Wistar Rats

Ferric nitrilotriacetate (Fe-NTA) is a well-established renal carcinogen. Here, we have shown that Pluchea lanceolata (PL) belonging to the family Asteraceae. PL attenuates Fe-NTA induced renal oxidative stress, hyperproliferative response and renal carcinogenesis in rats. It promoted DEN (N-diethyl nitrosamine) initiated renal carcinogenesis by increasing the percentage incidence of tumors and induces early tumor markers viz. ornithine decarboxylase (ODC) and renal DNA synthesis. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) also enhances renal lipid peroxidation (LPO), xanthine oxidase (XO) and hydrogen peroxide (H₂O₂) generation with reduction in renal glutathione content (GSH), antioxidant enzymes, viz., glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), glucose-6-phosphate dehydrogenase and phase-II metabolizing enzymes such as glutathione-S-transferase and quinone reductase (QR). It also enhances blood urea nitrogen (BUN) and serum creatinine. Oral treatment of rats with PL extract (100 and 200 mg/kg body weight) resulted in significant decrease in lipid peroxidation (LPO), xanthine oxidase (XO), H₂O₂ generation, blood urea nitrogen (BUN), serum creatinine, renal ODC activity, DNA synthesis (p < 0.001) and incidence of tumors. Renal glutathione content (p < 0.01), its metabolizing enzymes (p < 0.001) and antioxidant enzymes were also recovered to significant level (p < 0.001). Thus, present study supports PL as a potent chemopreventive agent and suppresses Fe-NTA-induced renal carcinogenesis and oxidative damage response in Wistar rat.     

Antioxidant capacity responsible for a hypocholesterolemia is independent of dietary cholesterol in adult rats fed rice protein

Dietary cholesterol and aging are major risk factors to accelerate oxidation process for developing hypercholesterolemia. The major aim of this study is to elucidate the effects of rice protein on cholesterol level and oxidative stress in adult rats fed with and without cholesterol. After 2 weeks of feeding, hepatic and plasma contents of cholesterol, reduced glutathione (GSH), oxidized glutathione (GSSG), malondialdehyde (MDA) and protein carbonyl (PCO) were measured. In liver, total antioxidative capacity (T-AOC), activities of antioxidant enzymes (total superoxide dismutase, T-SOD; catalase, CAT), glutathione metabolizing enzyme activities and gene expression levels (γ-glutamylcysteine synthetase, γ-GCS; glutathione reductase, GR; glutathione peroxidase, GPx) were determined. Under cholesterol-free/enriched dietary condition, T-AOC, activities of T-SOD and CAT, glutathione metabolism related enzymes' activities and mRNA levels (γ-GCS, GR and GPx) were effectively stimulated by rice proteins as compared to caseins. Compared with caseins, rice proteins significantly increased hepatic and plasma GSH contents, whereas hepatic and plasma accumulations of MDA, PCO and GSSG were significantly reduced by rice protein-feedings. As a result, the marked reductions of cholesterol in the plasma and in the liver were observed in adult rats fed rice proteins with and without cholesterol. The present study demonstrates that the hypocholesterolemic effect of rice protein is attributable to inducing antioxidative response and depressing oxidative damage in adult rats fed cholesterol-free/enriched diets. Results suggest that the antioxidant capability involved in the hypocholesterolemic action exerted by rice protein is independent of dietary cholesterol during adult period.     

Suppressive effects of dietary curcumin on the increased activity of renal ornithine decarboxylase in mice treated with a renal carcinogen, ferric nitrilotriacetate

Curcumin, a natural, biologically active compound extracted from rhizomes of Curcuma species, has been shown to act as a biological response modifier in various disorders. We have reported previously that the dietary supplementation of curcumin enhances the activities of antioxidant and phase II metabolizing enzymes in mice (M. Iqbal, S.D. Sharma, Y. Okazaki, M. Fujisawa, S. Okada, Dietary supplementation of curcumin enhances antioxidant and phase II metabolizing enzymes in ddY mice: possible role in protection against chemical carcinogenesis and toxicity, Pharmacol and Toxicol. 92 (2003) 33_38.) and inhibits ferric nitrilotriacetate (Fe-NTA) induced oxidative injury of lipids and DNA in vitro (M. Iqbal, Y. Okazaki, S. Okada, In vitro curcumin modulates Ferric Nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H(2)O(2))-induced peroxidation of microsomal membrane lipids and DNA damage, Teratogenesis Carcinogenesis and Mutagenesis Supplement 23 (2003) 151-160.). In our present study, Fe-NTA, a known complete renal carcinogen, which generate ROS in vivo, was given intraperitoneally to mice and curcumin was tested for its ability to inhibits oxidative stress and the activity of ornithine decarboxylase (ODC) as well as histopathological changes in the kidney. Substantial changes in glutathione, antioxidant enzymes as well as changes in phase II metabolizing enzymes were observed in the kidney at 12 h after treatment with Fe-NTA (9.0 mg Fe/kg body weight). Effect of oxidative stress induced by Fe-NTA were also demonstrated by the increase in lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and 4-hydroxy-2-nonenal (HNE)-modified proteins in kidney. Likewise, the level of protein carbonyl contents, an indicator of protein oxidation was also increased after Fe-NTA administration. However, the changes in these parameters were restored to normal in curcumin-pretreated mice. The ODC activity in the kidney was significantly increased by Fe-NTA, while the increased ODC activity induced by Fe-NTA was normalized in curcumin-pretreated mice. In addition, curcumin pretreatment almost completely prevented kidney biomolecules from oxidative damage and protected the tissue against observed histopathological alterations.