The effect of resveratrol on glycation and oxidation products in plasma and liver of chronic methylglyoxal-treated rats.

BACKGROUND: Methylglyoxal (MG) is a highly reactive dicarbonyl compound. It is produced by processes like glycolysis, glucose autooxidation, lipid peroxidation, and protein glycation. It is a major precursor of advanced glycation end products (AGE). It also exacerbates oxidative stress in the organism. Although there are some in vitro studies investigating the effect of resveratrol (RES) as an antioxidant and antiglycating agent on MG-induced toxicity, in vivo effect of RES is unknown. Therefore, we aimed to investigate the efficiency of RES in chronic MG-treated rats. METHODS: Rats were given incrementally increased doses (100-300 mg/kg) of MG in drinking water for ten weeks. RES (10 mg/kg ip) was administered together with MG. Reactive oxygen species (ROS) formation, thiobarbituric reactive substances (TBARS), protein carbonyl (PC), advanced oxidation protein products (AOPP) and AGE levels as well as ferric reducing antioxidant power (FRAP) values were determined in plasma and liver. RESULTS: Significant increases in plasma TBARS, PC, AOPP and AGE and fructosamine levels were detected in MG-treated rats. However, plasma ROS and FRAP levels remained unchanged. Hepatic ROS, TBARS, PC and AOPP, but not AGE and FRAP levels were also increased in MG-treated rats. RES treatment diminished high levels of plasma PC, AOPP and AGE levels in MG-treated rats. Additionally, significant decreases in hepatic ROS, TBARS, PC and AOPP levels together with histopatological amelioration were detected due to RES treatment in MG-treated rats. CONCLUSIONS: Our results indicate that RES may be considered as a protective agent against glycoxidative stress generated by in vivo MG treatment.

The effect of carnosine on methylglyoxal-induced oxidative stress in rats.

Methylglyoxal (MG) is generated from glycolytic metabolites, lipid peroxidation, glucose autooxidation and protein glycation. It is a prooxidant inducing oxidative stress and formation of advanced glycation end products (AGE). Effect of carnosine (CAR) as an antioxidant on toxicity due to MG has generated interest. In this study, rats were given incrementally increased doses (100-300 mg/kg) of MG in drinking water for ten weeks. CAR (250 mg/kg i.p.) was administered with MG. Plasma thiobarbituric reactive substances (TBARS), protein carbonyl (PC), advanced oxidation protein products (AOPP) and AGE levels were elevated by MG, and CAR decreased PC, AOPP and AGE levels. MG increased liver reactive oxygen species (ROS), TBARS, PC and AOPP levels, which were decreased by CAR. Thus, in vivo role of CAR on chronic MG administration was observed to suppress the generated hepatic and plasma oxidative stress.

The effect of dietary curcumin and capsaicin on hepatic fetuin-A expression and fat accumulation in rats fed on a high-fat diet.

Effects of curcumin (turmeric) and capsaicin (red pepper) on hepatic fat accumulation and fetuin-A expression in rats fed high-fat diet (HFD) is aimed to be investigated. Male Sprague-Dawley rats received HFD (60% of total calories from fat) and 0.15 g capsaicin/kg HFD and/or 1.5 g curcumin/kg HFD for 16 weeks. Hepatic AMPK, p-AMPK and fetuin-A expressions were determined by western blotting, liver lipid levels were measured with colorimetric methods and serum fetuin-A, insulin, leptin and adiponectin levels were detected using commercial ELISA kits. HFD increased hepatic lipid levels, fetuin-A expression and serum leptin, insülin and fetuin-A levels. Curcumin and capsaicin treatments significantly reduced hepatic fat accumulation and leptin levels; liver fetuin-A expression was decreased significantly by the curcumin treatment. Curcumin and capsaicin treatments attenuated hepatic fat accumulation and increased leptin levels related to inflammation. The suppression of hepatic fetuin-A expression is observed to be especially sensitive to curcumin.

Effect of curcumin on hepatic heme oxygenase 1 expression in high fat diet fed rats: is there a triangular relationship?

High fat diet (HFD) is associated with oxidative stress induced fatty liver. Curcumin, an extract of Curcuma longa, has been shown to possess potent antioxidant and hypolipidemic properties. In this study, we investigated the effect of curcumin treatment on hepatic heme oxygenase-1 (HO-1) expression along with pro-oxidant-antioxidant status and lipid accumulation in rats fed an HFD. Male Sprague-Dawley rats were distributed among 4 groups: Group 1, which was fed the control diet (10% of total calories from fat); Group 2, which was fed the HFD (60% of total calories from fat); and groups 3 and 4, which received the HFD supplemented with curcumin and the control diet supplemented with curcumin (1 g/kg diet; w/w), respectively, for 16 weeks. HFD caused increases in hepatic lipid levels, production of reactive oxygen species, and lipid peroxidation. Further, HO-1 expression was significantly decreased. Histopathological examination showed hepatic fat accumulation and slight fibrotic changes. Curcumin treatment reduced hepatic lipids and oxidative stress parameters, and HO-1 expression was significantly increased. These findings suggest that increased HO-1 expression, along with suppressed oxidative stress as well as reduced hepatic fat accumulation and fibrotic changes, contribute to the beneficial effects of curcumin in attenuating the pathogenesis of fatty liver induced metabolic diseases.

Protective effect of Nigella sativa oil against binge ethanol-induced oxidative stress and liver injury in rats.

AIM: Nigella sativa L. (Ranunculaceae) is considered as a therapeutic plant-based medicine for liver damage. In this study, the aim was to study the effect of Nigella sativa oil (NSO) pretreatment on ethanol-induced hepatotoxicity in rats. METHOD: Rats were given Nigella sativa oil at doses of 2.5 and 5.0 mL·kg(-1), orally for 3 weeks, followed by oral ethanol (EtOH) administration (5 g·kg(-1)) every 12 h three times (binge model). RESULTS: Binge ethanol application caused significant increases in plasma transaminase activities and hepatic triglyceride and malondialdehyde (MDA) levels. It decreased hepatic glutathione (GSH) levels, but did not change vitamins E and vitamin C levels and antioxidant enzyme activities. NSO (5.0 mL·kg(-1)) pretreatment significantly decreased plasma transaminase activities, hepatic MDA, and triglyceride levels together with amelioration in hepatic histopathological findings. CONCLUSION: NSO pretreatment may be effective in protecting oxidative stress-induced hepatotoxicity after ethanol administration.

Effect of carnosine alone or combined with alpha-tocopherol on hepatic steatosis and oxidative stress in fructose-induced insulin-resistant rats

A diet high in fructose (HFr) induces insulin resistance in animals. Free radicals are involved in the pathogenesis of HFr-induced insulin resistance. Carnosine (CAR) is a dipeptide with antioxidant properties. We investigated the effect of CAR alone or in combination with α-tocopherol (CAR + TOC) on HFr-induced insulin-resistant rats. Rats fed with HFr containing 60 % fructose received CAR (2 g/L in drinking water) with/without TOC (200 mg/kg, i.m. twice a week) for 8 weeks. Insulin resistance, serum lipids, inflammation markers, hepatic lipids, lipid peroxides, and glutathione (GSH) levels together with glutathione peroxidase (GSH-Px) and superoxide dismutase 1 (CuZnSOD; SOD1) activities and their protein expressions were measured. Hepatic histopathological examinations were performed. HFr was observed to cause insulin resistance, inflammation and hypertriglyceridemia, and increased triglyceride and lipid peroxide levels in the liver. GSH-Px activity and expression decreased, but GSH levels and SOD1 activity and expression did not alter in HFr rats. Hepatic marker enzyme activities in serum increased and marked macro- and microvesicular steatosis were seen in the liver. CAR treatment did not alter insulin resistance and hypertriglyceridemia, but it decreased steatosis and lipid peroxidation without any change in the antioxidant system of the liver. However, CAR + TOC treatment decreased insulin resistance, inflammation, hepatic steatosis, and lipid peroxidation and increased GSH-Px activity and expression in the liver. Our results may indicate that CAR + TOC treatment is more effective to decrease HFr-induced insulin resistance, inflammation, hepatic steatosis, and dysfunction and pro-oxidant status in rats than CAR alone

Effect of carnosine alone or combined with α-tocopherol on hepatic steatosis and oxidative stress in fructose-induced insulin-resistant rats.

A diet high in fructose (HFr) induces insulin resistance in animals. Free radicals are involved in the pathogenesis of HFr-induced insulin resistance. Carnosine (CAR) is a dipeptide with antioxidant properties. We investigated the effect of CAR alone or in combination with α-tocopherol (CAR + TOC) on HFr-induced insulin-resistant rats. Rats fed with HFr containing 60% fructose received CAR (2 g/L in drinking water) with/without TOC (200 mg/kg, i.m. twice a week) for 8 weeks. Insulin resistance, serum lipids, inflammation markers, hepatic lipids, lipid peroxides, and glutathione (GSH) levels together with glutathione peroxidase (GSH-Px) and superoxide dismutase 1 (CuZnSOD; SOD1) activities and their protein expressions were measured. Hepatic histopathological examinations were performed. HFr was observed to cause insulin resistance, inflammation and hypertriglyceridemia, and increased triglyceride and lipid peroxide levels in the liver. GSH-Px activity and expression decreased, but GSH levels and SOD1 activity and expression did not alter in HFr rats. Hepatic marker enzyme activities in serum increased and marked macro- and microvesicular steatosis were seen in the liver. CAR treatment did not alter insulin resistance and hypertriglyceridemia, but it decreased steatosis and lipid peroxidation without any change in the antioxidant system of the liver. However, CAR + TOC treatment decreased insulin resistance, inflammation, hepatic steatosis, and lipid peroxidation and increased GSH-Px activity and expression in the liver. Our results may indicate that CAR + TOC treatment is more effective to decrease HFr-induced insulin resistance, inflammation, hepatic steatosis, and dysfunction and pro-oxidant status in rats than CAR alone.

Is thioredoxin reductase involved in the defense against DNA fragmentation in varicocele?

We aimed to investigate the role of thioredoxin reductase (TR) and inducible heat shock protein 70 (iHsp70) and their relationship with sperm quality in varicocele (VAR) patients. Semen samples were obtained from 16 subfertile men diagnosed as VAR and 10 fertile men who applied to the Andrology Laboratory of Istanbul Medical Faculty of Istanbul University. The sperm TR and iHsp 70 expression levels were determined using Western blot analysis. The TR activity of the sperm was assayed spectrophometrically. The sperm quality was evaluated both by conventional sperm analysis and by a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique that assayed DNA-fragmented spermatozoa in semen samples. The percentage of TUNEL-positive spermatozoa in the VAR group (16.3%± 5.6%) was higher than that in the fertile group (5.5%± 1.9%). Significant inverse correlations were detected between the percentage of TUNEL-positive cells and both the concentration (r=-0.609; P=0.001) and motility (r=-0.550; P=0.004) of spermatozoa. Both the TR expression and activity were increased significantly in the VAR group (U=22.0; P=0.001 and U=33.5; P=0.012, respectively) as analyzed using the Mann-Whitney U Wilcoxon rank sum W test. Furthermore, significant positive correlations were found between TR expression and activity (r=0.406; P=0.040) and between TR expression and the percentage of TUNEL-positive cells (r=0.665; P=0.001). Sperm iHsp70 expression did not differ between the VAR and fertile groups. In conclusion, increased sperm TR expression might be a defense mechanism against apoptosis in the spermatozoa of men with VAR.

Mystery of idiopathic male infertility: is oxidative stress an actual risk?

OBJECTIVE: To study the role of oxidative stress in sperm dysfunction in Turkish idiopathic infertile men. DESIGN: Prospective study. SETTING: Medical laboratory. PATIENT(S): Semen samples from 28 idiopathic infertile men and 14 fertile men. INTERVENTION(S): Sperm DNA fragmentation and reactive oxygen species (ROS) formation were assayed with the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) test and 2',7'-dichlorodihydrofluorescein, respectively. Seminal plasma protein carbonyl groups (PC), nitrotyrosine (NT), malondialdehyde (MDA), and total thiol (SH) levels and ferric reducing antioxidant power (FRAP) were determined. MAIN OUTCOME MEASURE(S): Sperm DNA fragmentation in relation to ROS formation and seminal plasma oxidative parameters. RESULT(S): The number of TUNEL-positive spermatozoa from idiopathic infertile men was higher than from fertile men, and ROS formation was increased as well in infertile males. A positive correlation was detected between TUNEL-positive cells and ROS content. Seminal plasma MDA, PC, and NT levels were elevated in idiopathic infertile males. No difference was observed in the total SH content and FRAP. Seminal plasma MDA levels correlated positively with both NT and PC levels. Positive correlations were detected between DNA fragmentation and MDA, NT, and PC of seminal plasma, and between sperm ROS content and MDA levels. CONCLUSION(S): The results of this study support the presence of oxidative stress in sperm dysfunction in Turkish idiopathic infertile men.

Effect of binge ethanol treatment on prooxidant-antioxidant balance in rat heart tissue.

Binge drinking of alcohol is known to cause cardiac dysfunction in some drinkers. This study was designed to examine the effect of ethanol on rat heart tissue with an experimental model mimicking human binge drinking. Female Sprague-Dawley rats were given ethanol diluted with normal saline (40%, v:v) by gavage at the dose of 5.0g/kg every 12h for 3 doses as total. Serum activities of lactate dehydrogenase (LDH), creatine phosphokinase (CK) and aspartate transaminase (AST) were determined. Endogenous lipid peroxidation was assessed by measuring the levels of malondialdehyde (MDA) in heart homogenates. In vitro susceptibility of tissues to oxidative stress was assessed by using two different media. Tissue glutathione (GSH) and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities were determined. All serum enzymatic activities were found markedly elevated in ethanol group. Binge ethanol administration significantly enhanced endogenous lipid peroxidation and caused an enhanced in vitro susceptibility to lipid peroxidation. Levels of reduced GSH and GSH-Px and GST activities were found unchanged as compared to controls. SOD activity was found significantly increased. As a conclusion, binge ethanol consumption which was applied to rats to investigate acute tissue injury, appeared to confirm the generation of oxidative stress in rat hearts.

Effect of artichoke leaf extract on hepatic and cardiac oxidative stress in rats fed on high cholesterol diet.

Hypercholesterolemia and lipid peroxidation play complementary roles in atherosclerosis. Artichoke (Cynara scolymus L., Asteraceae) leaf extract (ALE), rich in antioxidants, has cholesterol-reducing effect. We investigated the effect of ALE on serum and hepatic lipid levels and pro-oxidant-antioxidant balance in the liver and heart of hypercholesterolemic rats. Rats were fed on 4% (w/w) cholesterol and 1% cholic acid (w/w) supplemented diet for 1 month. ALE (1.5 g/kg/day) was given by gavage during the last 2 weeks. High cholesterol (HC) diet caused significant increases in serum and liver cholesterol and triglyceride levels. It increased malondialdehyde (MDA) and diene conjugate (DC) levels in both tissues. Hepatic vitamin E levels and hepatic and cardiac glutathione peroxidase (GSH-Px) activities decreased, but superoxide dismutase and glutathione transferase activities, glutathione, and vitamin C levels remained unchanged due to HC diet. Serum cholesterol and triglyceride levels and ratio of cholesterol to high-density lipoprotein (HDL)-cholesterol decreased in ALE plus HC-treated rats, but liver cholesterol and triglyceride levels remained unchanged. Significant decreases in hepatic and cardiac MDA and DC levels and increases in hepatic vitamin E and GSH-Px activities were observed in ALE-treated hypercholesterolemic rats. Our results indicate that ALE decreases serum lipids and hypercholesterolemia-induced pro-oxidant state in both tissues.

Effect of carnosine against thioacetamide-induced liver cirrhosis in rat.

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Oxidative stress has been proposed to be involved in thioacetamide (TAA)-induced liver cirrhosis in rats, that is similar to human disease. In this study we aimed to investigate the role of carnosine on the development of TAA-induced cirrhosis. 200mg TAA/kg body weight has been given i.p. twice a week for three months to female wistar rats. Another group received same dose of TAA in the same pattern plus 2g carnosine/L of drinking water for three months. TAA administration resulted in hepatic fibrosis, significant increases in plasma transaminase activities as well as hepatic hydroxyproline and lipid peroxide levels, while liver glutathione (GSH) and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) protein expressions and activities decreased. Carnosine was found to behave as an antioxidant reducing malondialdehyde (MDA) and diene conjugate (DC) levels although it was not effective on increased transaminase activities and decreased antioxidants. It also did not affect the histopathological changes observed in TAA group. Thus our findings indicate that carnosine appears to attenuate peroxidation as an antioxidant itself but does not seem to prevent the development of TAA-induced cirrhotic process.

Effect of taurine treatment on pro-oxidant-antioxidant balance in livers and brains of old rats.

The effect of taurine treatment on antioxidant defense in liver and brain tissues of old rats was investigated. Endogenous malondialdehyde (MDA) and diene conjugate (DC), ascorbic acid (AA)- and NADPH-induced lipid peroxide levels as well as non-enzymatic (glutathione--GSH, vitamin E and vitamin C) and enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and glutathione transferase) were determined in livers and brains of young (5 months), old (22 months), and taurine-treated old rats. Taurine (2%, w/v; in drinking water) was administered to old rats for 6 weeks. Taurine levels decreased in the liver and brain of old rats compared to young rats.MDA and DC levels increased, GSH levels decreased, but induced lipid peroxidation remained unchanged in livers of aged rats. Oxidative stress parameters did not change in brains of aged rats. Taurine treatment resulted in significant increases in taurine levels, decreases in MDA and DC levels and increases in GSH levels in livers of old rats. Taurine treatment also increased brain taurine levels. However, no significant changes were detected in lipid peroxidation and antioxidant system in brains of old rats following taurine treatment. Accordingly, in old rats the liver seems more susceptible to age-related lipid peroxidation increases and taurine level changes than the brain. Thus, taurine supplementation seems to be useful for decreasing hepatic oxidative stress in aging.

Effect of pretreatment with artichoke extract on carbon tetrachloride-induced liver injury and oxidative stress.

Artichoke is a plant with antioxidant properties. In this study, we investigated the effect of artichoke extract pretreatment on carbon tetrachloride (CCl4)-induced oxidative stress and hepatotoxicity. Rats were given artichoke leaf extract (1.5g/kg/day) by gavage for 2 weeks and after then CCl4 (1ml/kg; i.p.) was applied. All rats were killed 24h after the CCl4 injection. CCl4 administration resulted in hepatic necrosis and significant increases in plasma transaminase activities as well as hepatic malondialdehyde (MDA) and diene conjugate (DC) levels in the liver of rats. Glutathione (GSH) and vitamin C levels decreased, but vitamin E levels increased in the liver of CCl4-treated rats. Hepatic superoxide dismutase (SOD) activities remained unchanged, but glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities decreased following CCl4 treatment. In rats pretreated with artichoke extract, significant decreases in plasma transaminase activities and amelioration in histopathological changes in the liver were observed following CCl4 treatment as compared to CCl4-treated rats. In addition, hepatic MDA and DC levels decreased, but GSH levels and GSH-Px activities increased without any change in other antioxidant parameters following CCl4 treatment in artichoke-pretreated rats. The present findings indicate that in vivo architoke extract administration may be useful for the prevention of oxidative stress-induced hepatotoxicity.

Lipid peroxidation potential and antioxidants in the heart tissue of beta-alanine- or taurine-treated old rats.

The aim of this study was to investigate the effect of the changes of taurine levels in the hearts of old rats on endogenous malondialdehyde (MDA) and diene conjugate (DC) levels and ascorbic acid (AA)- and NADPH-induced lipid peroxidation as well as non-enzymatic (glutathione, vitamin E and vitamin C) and enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and glutathione transferase). Two groups of old (22 mo) rats were treated with beta-alanine (3%, w/v; in drinking water), a taurine depleting agent, or taurine (2% w/v; in drinking water) for 6 wk. Significant decreases were observed in taurine contents of hearts in old rats as compared to young (5 mo) rats. We found that MDA and DC levels and AA- and NADPH-induced lipid peroxidation increased, but non-enzymatic and enzymatic antioxidants did not alter in heart homogenates of aged rats. beta-Alanine administration resulted in significant decreases in heart taurine levels of old rats. This treatment did not cause further increases in MDA or DC levels or changes in antioxidants. However, AA- and NADPH-induced lipid peroxidation was higher than that of old rats. Taurine treatment caused significant increases in heart taurine levels of old rats. This treatment was found to decrease endogenous MDA and DC levels without affecting the antioxidant system in the heart homogenates of aged rats. AA- and NADPH-induced lipid peroxidation was also reduced in old rats when given taurine, although not statistically significantly. Our results indicate that the changes in heart taurine levels may influence the susceptibility of heart tissue to lipid peroxidation in aged rats and that taurine supplementation has protective effects on age-dependent oxidative stress in heart tissue.

Role of carnosine in preventing thioacetamide-induced liver injury in the rat.

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). In this study, we investigated the effect of carnosine treatment on TAA-induced oxidative stress and hepatotoxicity. Rats were injected intraperitoneally with TAA (500 mg/kg) and carnosine (250 mg/kg, intraperitoneal) was co-administered with TAA. All animals were killed 24 h after injections. TAA administration resulted in hepatic necrosis, significant increases in plasma transaminase activities as well as hepatic lipid peroxide levels. In addition, hepatic antioxidant system was found to be depressed following TAA administration. When carnosine was co-administered with TAA in rats, plasma transaminase activities were found to approach to normal values in rats. Histological findings also suggested that carnosine has preventive effect on TAA-induced hepatic necrosis. Carnosine treatment caused significant decreases in lipid peroxide levels in TAA-treated rats without any changes in enzymatic and non-enzymatic antioxidants except vitamin E in the liver of rats. Our findings indicate that carnosine, in vivo may have a preventive effect on TAA-induced oxidative stress and hepatotoxicity by acting as an non-enzymatic antioxidant itself.

The role of heat shock protein 70 (Hsp 70) in male infertility: is it a line of defense against sperm DNA fragmentation?

OBJECTIVE: To clarify the role of heat shock protein 70 (Hsp 70) and its relation with DNA damage in male infertility. DESIGN: Prospective study. SETTING: Andrology laboratory of Istanbul Medical Faculty. PATIENT(S): Semen samples from 37 infertile men and 13 fertile men (as controls). INTERVENTION(S): The percentage of DNA fragmentation was assayed with the use of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). Sperm Hsp 70 expression was determined by using Western blot analysis. MAIN OUTCOME MEASURE(S): Both the percentages of sperm DNA fragmentation and Hsp 70 expression were correlated with semen analysis parameters. RESULTS: TUNEL-positive spermatozoa in the infertile group (18.7% for asthenospermics and 13.0% for oligoasthenospermics) were higher than the fertile group (4.9%). Significant inverse correlations were detected between percentage of TUNEL-positive cells and both concentration (r = -0.487) and motility (r = -0.377) of spermatozoa. No expression of Hsp 70 was observed in azospermic group, whereas Hsp 70 levels were found increased significantly in infertile group (U = 62 for asthenospermics and U = 38 for oligoasthenospermics) compared to fertile group as analyzed by using Mann-Whitney U Wilcoxon rank sum test. Furthermore, significant positive correlation was found between percentage of TUNEL-positive cells and Hsp 70 expression (r = 0.357). CONCLUSION(S): Hsp 70 expression may have been increased as a protective mechanism against apoptosis in spermatozoa of infertile men.

Peroxynitrite induced decrease in Na+, K+-ATPase activity is restored by taurine.

AIM: Peroxynitrite (ONOO-) is a powerful oxidant shown to damage membranes. In the present study, the effect of taurine on changes of liver plasma membrane Na+, K+-ATPase induced by ONOO- was investigated. METHODS: Liver plasma membrane was exposed to ONOO- with or without taurine. Na+, K+-ATPase activity and lipid peroxidation as thiobarbituric acid reactive substances (TBARS) levels were measured. RESULTS: Different concentrations of ONOO- (100, 200, 500, and 1000 micromol/L) were found to decrease liver plasma membrane Na+, K+-ATPase activity significantly. The depletion of enzyme activity was not concentration dependent. Effects of different concentrations of taurine on liver plasma membrane Na+, K+-ATPase activity were also measured. Taurine did not cause any increase in enzyme activity. When plasma membranes were treated with 200 micromol/L ONOO- with different concentrations of taurine, a restoring effect of taurine on enzyme activity was observed. TBARS levels were also measured and taurine was found to decrease the elevated values. CONCLUSION: Taurine is observed to act as an antioxidant of ONOO- to decrease lipid peroxidation and thus affect liver plasma membrane Na+, K+-ATPase by restoring its activity.

The effect of betaine treatment on triglyceride levels and oxidative stress in the liver of ethanol-treated guinea pigs.

We investigated the effect of betaine supplementation on ethanol induced steatosis and alterations in prooxidant and antioxidant status in the liver of guinea pigs. Animals were fed with normal chow or betaine containing chow (2% w/w) for 30 days. Ethanol (3 g/kg, i.p.) was given for the last 10 days. We found that ethanol treatment caused significant increases in plasma transaminase activities, hepatic triglyceride and lipid peroxide levels. Significant decreases in glutathione (GSH), alpha-tocopherol and total ascorbic acid (AA) levels were also observed, but hepatic superoxide dismutase, glutathione peroxidase and glutathione transferase activities remained unchanged as compared with those in controls. Betaine treatment together with ethanol in guinea pigs is found to decrease hepatic triglyceride, lipid peroxide levels and serum transaminase activities and to increase GSH levels. No changes in alpha-tocopherol and total AA levels and antioxidant enzyme activities were observed with betaine treatment in alcohol treated guinea pigs. In addition, histopathological assessment of guinea pigs showed that betaine reduced the alcoholic fat accumulation in the liver. Based on these data, betaine treatment has a restoring effect on the alterations in triglyceride, lipid peroxide and GSH levels following ethanol ingestion.