Hepatic Reduced Glutathione Content Research Articles

Effects of Dietary Lactic Acid Supplementation on the Activity of Digestive and Antioxidant Enzymes, Gene Expressions, and Bacterial Communities in the Intestine of Common Carp, Cyprinus carpio

The present study investigated the effects of dietary lactic acid (LA) supplementation on the growth performance, intestinal digestive/antioxidant enzymes’ activities, gene expression, and bacterial communities in common carp, Cyprinus carpio. Four diets were formulated to contain 0 g/kg LA (control), at 2.5 g/kg LA (2.5LAC), 5 g/kg LA (5LAC), and 10 g/kg LA (10LAC) and offered to the fish over a period of 56 days. The results showed that dietary 5 g/kg LA supplementation improved growth performance and feed efficiency in the fish. All LA treatments exhibited significant elevations in the intestinal trypsin and chymotrypsin activities, whereas the intestinal lipase, amylase, and alkaline phosphatase activities exhibited significant elevations in the 5LAC and 10LAC treatments. All LA treatments exhibited significant elevations in the intestinal heat shock protein 70, tumor necrosis factor-alpha, interleukin-1 beta, and defensin gene expressions, and the highest expression was observed in the 5LAC treatment. Additionally, dietary LA treatment significantly increased the lysozyme expression and Lactobacillus sp. population in the intestine of the fish, and the highest values were observed in the 5LAC and 10LAC treatments. Aeromonas sp. and Vibrio sp. populations decreased in the LA treatments, and the lowest Aeromonas sp. population was observed in the 10LAC treatment. The intestinal mucin2 and mucin5 expressions, and the hepatic reduced glutathione content, significantly increased, whereas hepatic glutathione peroxidase, glutathione reductase, and malondialdehyde significantly decreased in the 5LAC and 10LAC treatments. In conclusion, dietary 5 g/kg LA is recommended for common carp feeding to improve growth rate, antioxidant capacity, and intestinal health.

Protein-Deficient Pigs Cannot Maintain Reduced Glutathione Homeostasis When Subjected to the Stress of Inflammation

The mechanisms responsible for depletion of systemic glutathione levels in nutritional deprivation and/or in infective and inflammatory conditions have not been fully established. We quantified the effects of protein undernutrition and experimental inflammation on the concentration and synthesis of reduced glutathione in the erythrocytes, liver and jejunal mucosa of young pigs. Two groups of five piglets consumed diets containing either 23 or 3% protein and, after 4 wk, were infused intravenously with [13C2]glycine before and 48 h after subcutaneous injections of turpentine. Erythrocyte, hepatic and intestinal mucosal reduced glutathione was quantified as the monobromobimane derivative by HPLC. Reduced glutathione synthesis was determined by measurements of the tracer/tracee ratio of reduced glutathione-bound glycine. In well-nourished piglets, turpentine injection had no effect on erythrocyte reduced glutathione concentrations or rate of synthesis. Protein undernutrition was associated with lower erythrocyte reduced glutathione concentrations (1.05 ± 0.04 vs. 1.32 ± 0.06 mmol/L, P < 0.01) and synthesis (42 ± 5 vs. 60 ± 5%/d), and turpentine inflammation caused a further fall in erythrocyte reduced glutathione concentration to 0.96 ± 0.05 mmol/L, despite a significant (P < 0.05) increase in reduced glutathione synthesis. The combination of protein undernutrition and inflammation had a marked effect on mucosal reduced glutathione concentration (37 ± 3% of control) and synthesis (65 ± 5% of control). Hepatic reduced glutathione concentration and synthesis did not differ in the two groups. We conclude that the biosynthetic supply of reduced glutathione is sufficient to withstand an inflammatory challenge in well-nourished piglets but not in protein-deficient animals.

High-dose testosterone supplementation disturbs liver pro-oxidant/antioxidant balance and function in adolescent male Wistar rats undergoing moderate-intensity endurance training.

In some countries, anabolic-androgenic steroid abuse is rampant among adolescent boys and young men, including some of those seeking physical fitness and/or pleasing appearance through various exercise types. This tactic carries the risk of severe harmful health effects, including liver injury. Most anabolic-androgenic steroid stacking protocols employed are based on the use of the ‘prototypic’ anabolic-androgenic steroid testosterone and/or its esters. There is a vast body of data on the effects of anabolic-androgenic steroids’ abuse combined with physical exercise training on the liver antioxidant barrier in adult subjects, whereas those concerning adolescents are scant. This study aimed to assess, in adolescent male Wistar rats undergoing a 6-week moderate-intensity endurance training (treadmill running), the influence of concurrent weekly supplementation with intramuscular testosterone enanthate (TE, 8 or 80 mg/kg body weight/week) on selected indices of liver status and oxidative stress. The rats were sacrificed, and their livers and blood samples were harvested two days after the last training session. High-dose TE treatment significantly reduced body and liver weight gains. Neither low-dose nor high-dose TE treatment affected liver α-tocopherol or γ-tocopherol content, whereas low-dose TE treatment significantly lowered hepatic reduced glutathione content. TE treatment significantly elevated liver thiobarbituric acid-reactive substances content and blood activities of alkaline phosphatase and γ-glutamyltransferase, but not of aspartate aminotransferase or alanine aminotransferase. Liver catalase activity was lowered by >50% in both TE-treated groups, while superoxide dismutase activity was significantly but slightly affected (−15%) only by the high-dose TE treatment. Glutathione peroxidase and glutathione reductase activities were not significantly altered. TE treatment significantly increased liver thiobarbituric acid-reactive substances content and lowered blood HDL-cholesterol, but did not significantly affect LDL-cholesterol or triglycerides level. In conclusion, high-dose TE treatment significantly disturbed liver antioxidant barrier and prooxidative-antioxidative balance and hence counteracted favorable effects of concurrent moderate-intensity endurance training in adolescent male rats.

Biochemical, functional, and histopathologic characterization of lomustine-induced liver injury in dogs.

To characterize the biochemical, functional, and histopathologic changes associated with lomustine-induced liver injury in dogs. I0 healthy purpose-bred sexually intact female hounds. Dogs were randomly assigned to receive lomustine (approx 75 mg/m2, PO, q 21 d for 5 doses) alone (n = 5) or with prednisone (approx 1.5 mg/kg, PO, q 24 h for 12 weeks; 5). For each dog, a CBC, serum biochemical analysis, liver function testing, urinalysis, and ultrasonographic examination of the liver with acquisition of liver biopsy specimens were performed before and at predetermined times during and after lomustine administration. Results were compared between dogs that did and did not receive prednisone. 7 of the I0 dogs developed clinical signs of liver failure. For all dogs, serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, bile acid concentrations, and liver histologic score increased and hepatic reduced glutathione content decreased over time. Peak serum ALT (r = 0.79) and ALP (r = 0.90) activities and bile acid concentration (r = 0.68) were positively correlated with the final histologic score. Prednisone did not appear to have a protective effect on histologic score. In dogs, liver enzyme activities, particularly ALT and ALP activities, should be closely monitored during lomustine treatment and acute increases in those activities may warrant discontinuation of lomustine to mitigate liver injury. Nonspecific ultrasonographic findings and abnormal increases in liver function tests were not detected until the onset of clinical liver failure. Glutathione depletion may have a role in lomustine-induced hepatopathy and warrants further investigation.

Orally administered octacosanol improves some features of high fructose-induced metabolic syndrome in rats.

We examined whether orally administered octacosanol, a long-chain aliphatic saturated alcohol, improves the features of high fructose-induced metabolic syndrome in rats. Five-week-old rats were fed a high fructose diet containing 60% fructose for 3 weeks. Then, the high fructose fed rats received a daily single oral administration of octacosanol (10 or 100 mg/kg body weight) with high fructose feeding for one week. Three- or four-week high fructose feeding increased insulin resistance, serum insulin, triglyceride, total cholesterol, free fatty acids, uric acid, and lipid peroxide concentrations, and hepatic triglyceride and cholesterol contents significantly and decreased serum high-density lipoprotein cholesterol and adiponectin concentrations significantly but did not affect blood pressure and hepatic lipid peroxide and reduced glutathione contents. Four-week high fructose feeding decreased hepatic ascorbic acid content significantly. Oral administration of octacosanol (10 or 50 mg/kg body weight) to high fructose-fed rats for the last 1-week fructose diet feeding attenuated these changes except serum insulin level and insulin resistance significantly and increased hepatic reduced glutathione content significantly. The higher dose of Oct decreased hepatic lipid peroxide content significantly. These results indicate that orally administered octacosanol improves dyslipidemia, hyperuricemia, hypoadiponectinemia, and oxidative stress associated with the features of high fructose-induced metabolic syndrome rats.

Effects of alpha lipoic acid on acrylamide-induced hepatotoxicity in rats.

Acrylamide (ACR) is a neurotoxicant, reproductive toxicant, and carcinogen in animal species. It is used in many industries and has been found to form naturally in foods cooked at high temperatures. Alpha-lipoic acid (ALA) is a naturally occurring antioxidant whose therapeutic effect has been related to its antioxidant activity. This study was carried out to study the protective effect of alpha lipoic acid on acrylamide induced perturbations in rat liver. Four groups of rats were studied viz., control rats, acrylamide treated rats, alpha lipoic acid treated rats, and alpha lipoic acid plus acrylamide treated rats. ACR and ALA treatment alone and together caused a signifi-cant increase in hepatic reduced glutathione content while a decrease in hepatic ascorbic content was observed when compared to control group. ALA pretreatment of acrylamide exposed rats caused no a signifi-cant alteration in superoxide dismutase activity but resulted in a tendency towards restoration of glutathione peroxidase and catalase activity to near normal levels. Gel electrophoresis showed fragmentation of DNA in the treated groups. The dose of ALA used in the present study afforded partial restoration of oxidative indices altered by ACR in rat liver.

Effect of dietary vitamin E and selenium supplementation on growth, body composition, and antioxidant defense mechanism in juvenile largemouth bass (Micropterus salmoide) fed oxidized fish oil

Six oxidized fish oil contained diets were formulated to investigate the effect of graded levels of vitamin E (V(E)) (α-tocopherol acetate: 160, 280, and 400 mg kg(-1)) associated with either 1.2 or 1.8 mg kg(-1) selenium (Se) on growth, body composition, and antioxidant defense mechanism of juvenile largemouth bass. Another control diet containing fresh fish oil with 160 mg kg(-1) V(E) and 1.2 mg kg(-1) Se was also prepared. Over a 12-week feeding trial, about 5 % of Micropterus salmoide fed diet OxSe1.2/V(E)160 showed inflammation and hemorrhage symptoms at the base of dorsal, pectoral, and tail fin. Fish in all treatments survived well (above 90 %). Feed intakes (88.42-89.58 g fish(-1)) of all treatments were comparable. Growth performances (weight gain and specific growth rate) and feed utilization (feed and protein efficiency ratio) were significantly impaired by dietary oil oxidation, and they did not benefit from neither V(E) nor Se supplementation. Regardless of dietary V(E) and Se supplementation, oxidized oil ingestion resulted in markedly decreased hepatosomatic index and intraperitoneal fat ratio. Oxidized oil ingestion also induced markedly lower liver and muscle lipid contents, and these effects could be alleviated by dietary Se supplementation. Dietary oil oxidation stimulated hepatic catalase activities relative to the control, and supplementation of V(E) abrogated this effect. Hepatic reduced glutathione content in the control was markedly higher than that of treatment OxSe1.2/V(E)160, without any significant differences comparing with the other oxidized oil receiving groups. Hepatic glutathione peroxidase activity and liver Se concentration reflected dietary Se profile, whereas liver V(E) level reflected dietary V(E) profile. Compared with the control, fish fed diet OxSe1.2/V(E)160 obtained markedly higher serum, liver and muscle malondialdehyde contents, which droppe significantly with increasing either V(E) or Se supplementation. In conclusion, the overall results in this study suggested that both V(E) and Se inclusion could protect largemouth bass from the oxidative damage challenged by dietary oil oxidation.

Melatonin improves metabolic syndrome induced by high fructose intake in rats

In this study, we examined whether melatonin improves metabolic syndrome induced by high fructose intake in male Wistar rats. Feeding of a diet containing 60% fructose (HFD) for 4 or 6 wk caused increased serum insulin, triglyceride, total cholesterol, free fatty acids, uric acid, leptin, and lipid peroxide concentrations as well as hepatic triglyceride and cholesterol concentrations, and relative intra-abdominal fat and liver weights. The 4- or 6-wk HFD feeding reduced serum high-density lipoprotein cholesterol and adiponectin concentrations. The 6-wk HFD feeding increased serum tumor necrosis factor-α concentration and hepatic lipid peroxide concentration and lowered hepatic reduced glutathione concentration. Daily intraperitoneal administration of melatonin (1 or 10mg/kg body weight), starting at 4-wk HFD feeding, attenuated these changes at 6-wk HFD feeding more effectively at its higher dose than at its lower dose. In an oral glucose tolerance test, rats with 4- or 6-wk HFD feeding showed higher serum insulin response curve and normal serum glucose response curve when compared with the corresponding animals that received the control diet. The 4- or 6-wk HFD feeding caused insulin resistance, judging from the scores of HOMR-IR and QUICKI, which are indices of insulin resistance. The daily administered melatonin (1 or 10mg/kg body weight) ameliorated the higher serum insulin response curve in the oral glucose tolerance test and insulin resistance at 6-wk HFD feeding more effectively at its higher dose than at its lower dose. These results indicate that melatonin improves metabolic syndrome induced by high fructose intake in rats.

고지방식이로 유도한 비만 흰쥐에서 Monascus pilosus 균사체 추출물의 간 손상 예방효과

본 연구는 Monascus pilosus mycelial ethanol extract (MPME)의 간 손상 예방 효과를 관찰할 목적으로 고지방-고콜레스테롤 식이로 유도한 비만 흰쥐(Sprague-Dawly계)를 대상으로 실험하였다. 실험동물은 정상 대조군(NC)과 고지방-고콜레스테롤 식이군(고지방식이군)으로 분류하였으며, 고지방식이군은 15% lard-1% cholesterol 첨가 5L79 diet로 3주간 성장시켜 비만을 유도한 후 고지방식이 대조군(HF), 0.5% MPME extract 첨가 고지방식이군(MPM) 및 2% CLA (conjugated linoleic acid) 첨가 고지방식이군(CLA)의 4개군 (n=5)으로 나누어 7주 동안 성장시켜 다음과 같은 결과를 얻었다. 1일 평균 체중증가량은 NC군은 3.48 g, HF군은 4.48 g인데 비하여 MPM군과 CLA군은 각각 3.09 g 및 4.38 g으로 HF군에 비하여 각각 31.03% 및 2.24%의 감소를 나타내었다. 체중에 대한 간 중량(%)은 모든 실험군에서 NC군에 비해 유의하게 증가하였으나 MPM군은 HF군에 비하여 유의하게 감소하였으며 CLA군은 HF군과의 차이를 보이지 않았다. 간 조직손상의 지표로 이용되는 혈청 ALT와 AST의 활성은 HF군에서는 NC군 보다 2.70배 및 2.55배가 각각 증가하였으며, CLA군은 NC군의 수준으로 회복되지는 못하였으나 HF군에 비해 현저히 감소하였고 MPM군에서는 정상상태인 NC군 수준으로 감소되었다. MPM군과 CLA군의 간조직 reduced glutathione의 함량은 HF군에 비해 높게 나타났으며, 이와 반대로 MPM 및 CLA군의 과산화지질 함량은 현저하게 낮았다. HF군의 간 조직 xanthine oxidoreductase (XOR)의 type O활성과 O/T ratio는 NC군에 비해 증가하였으며, MPM과 CLA군의 경우에는 HF군에 비해 감소하였다. 또한 HF군의 간 조직 superoxide dismutase (SOD) 및 glutathione Stransferase (GST)의 활성은 NC군에 비해 감소하였으나 MPM과 CLA군에서는 HF군에 비해 증가하였다. 이상의 결과를 종합해 볼 때, 본 실험의 결과로서는 MPME의 정확한 간 보호기전을 알 수가 없으나 MPME는 지방의 흡수를 억제함과 동시에 SOD와 같은 ROS 제거계 효소의 유도를 통하여 비만과 간 조직 손상을 예방하거나 경감시키는 효과가 있는 것으로 생각된다. Hepatoprotective effects of Monascus pilosus mycelial ethanol extract (MPME) were examined in high-fat diet induced-obese rats. The rats were randomly divided into 2 groups; normal control (NC) and a high-fat and high cholesterol diet group (HFC). The HFC diet group was fed a 5L79 diet supplemented with 15% lard and 1% cholesterol for 3 weeks for induction of obesity. And then, the rats were divided into 4 groups (n=5); the NC, a HFC diet obesity control group (HF), 0.5% MPME supplemented HFC diet group (MPM), and 2% conjugated linoleic acid (CLA) supplemented HFC diet group for 7 weeks. Whereas the daily weight gain of NC and HFC groups were 3.48 g and 4.48 g, respectively, those of MPM and CLA were 3.09 g and 4.38 g, respectively. Furthermore, activity of serum alanine and aspartic aminotransferase in HF was markedly higher than those of NC group, but, the activity in MPM and CLA was significantly lower than HF. Hepatic reduced glutathione content in MPM and CLA was higher than HF. On the contrary, hepatic lipid peroxide content in MPM and CLA was significantly lower than HF. In conclusion, although the precise mechanisms of the hepatoprotective effects of the MPME in this study are unknown, our study provides experimental evidence that MPME may prevent obesity and hepatic damage by high-fat and high cholesterol diet via inhibition of lipid absorption and induction of reactive oxygen spices scavenging enzyme such as superoxide dismutase.

Perillyl alcohol protects against ethanol induced acute liver injury in Wistar rats by inhibiting oxidative stress, NFκ-B activation and proinflammatory cytokine production

Oxidative stress and inflammation are two major etiological factors that are suggested to play key roles in the development of ethanol induced liver injury. Release of proinflammatory cytokine like tumor necrosis factor alpha (TNF-α) and activation of nuclear factor kappa-B (NFκ-B) may strongly intensify inflammation and cell damage. Additionally, reactive oxygen species (ROS) also exerts significant effect in this whole cell signaling machinery. The present study was designed to investigate the protective effects of perillyl alcohol (POH) on ethanol-induced acute liver injury in Wistar rats and its probable mechanism. We have successfully demonstrated that pre-treatment with POH, besides exerting antioxidant activity might be able to modulate TNF-α release and NFκ-B activation. Rats were divided into five groups and treated with ethanol or POH via an intragastric tube for one week. Control group was treated with vehicle, and ethanol treated group was given ethanol (5 g/kg body wt). Animal of treatment groups were pretreated with POH (50 & 100 mg/kg body wt) and have been given ethanol. Serum aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase and hepatic malondialdehyde were increased significantly by ethanol treatment. Ethanol administration decreased hepatic reduced glutathione content and various antioxidant enzymes activity. TNF-α production and NFκ-B activation was also found to be increased after ethanol administration. POH pre-treatment significantly ameliorates ethanol induced acute liver injury possibly by inhibition of lipid peroxidation, replenishment of endogenous enzymatic and non-enzymatic defense system, downregulation of TNF-α as well as NFκ-B.

An insight into the possible protective effect of pyrrolidine dithiocarbamate against lipopolysaccharide-induced oxidative stress and acute hepatic injury in rats

Lipopolysaccharide (LPS) is a major cell wall molecule of Gram-negative bacteria known to stimulate the synthesis and secretion of several toxic metabolites, such as reactive oxygen species. In this study, the effect of pyrrolidine dithiocarbamate (PDTC), an antioxidant with nuclear factor-κB inhibitor activity, was evaluated in LPS-induced oxidative stress and acute hepatic injury in rats. Animals were pretreated for 3 consecutive days with PDTC (200mg/kg/day, i.p.) or saline and animals were then challenged with LPS (6mg/kg, i.p.) or saline. Six hours after LPS injection, animals were decapitated and blood and liver samples were collected to assess the chosen biochemical parameters. Saline-pretreated animals challenged with LPS revealed extensive liver damage, as evidenced by increases in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transferase (γ-GT). Also, LPS treatment resulted in significant increases in serum lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α) and nitrite levels. Furthermore, LPS challenge caused oxidative stress as indicated by an increase in hepatic lipid peroxidation measured as thiobarbituric acid reactive substances (TBARS) and a decrease in hepatic reduced glutathione concentration (GSH) as well as decreased activities of superoxide dismutase (SOD) and catalase in hepatic tissues. The administration of PDTC prior to LPS challenge resulted in improved liver functions as evidenced by the decline in serum AST, ALT, γ-GT levels and reduction in serum LDH, TNF-α and nitrite levels. Moreover, PDTC reduced the chosen lipid peroxidation marker, TBARS and increased GSH concentration, and SOD and catalase activities in hepatic tissues. These results indicate that PDTC may be a useful pharmacological agent in alleviating LPS-induced oxidative stress and acute hepatic injury.

Effect of schisandrin B and sesamin mixture on CCl4‐induced hepatic oxidative stress in rats

To study the effects of schisandrin B and sesamin mixture on carbon tetrachloride (CCl(4))-induced hepatic oxidative stress in male Sprague-Dawley rats. The rats were randomly assigned to five groups: control group (olive oil injection), CCl(4) group (CCl(4) injection), silymarin group (CCl(4) injection combined with supplementation of silymarin, 7.5 mg/kg/day), low dose group (CCl(4) injection combined with supplementation of schisandrin B and sesamin mixture at a low dose, 43 mg/kg/day) and high dose group (CCl(4) injection combined with the supplementation of schisandrin B and sesamin mixture at a high dose, 215 mg/kg/day). The hepatic superoxide dismutase and glutathione peroxidase activities of rats in the low dose and high dose groups were increased significantly compared with those in the CCl(4) group. The hepatic reduced glutathione concentration in the silymarin, low dose and high dose groups were increased significantly (48%, 45% and 53%, respectively) when compared with those of the CCl(4) group. In addition, the concentration of glutathione in the erythrocytes of the low dose group was significantly higher than the CCl(4) group by 25%. These results suggest that the schisandrin B-sesamin mixture exerted a hepatoprotective effect by improving the antioxidative capacity in rats under CCl(4)-induced hepatic oxidative stress.

Pre-treatment by &lt;i&gt;n&lt;/i&gt;-hexane extract of &lt;i&gt;Phyllanthus niruri&lt;/i&gt; can alleviate paracetamol-induced damage of the rat liver

The present study aimed to obtain and evaluate remedy against viral hepatitis with Phyllanthus niruri (Bhui amla). Viral infection and toxic doses of paracetamol produce similar pattern of hepatotoxicity. Hepatotoxicity was induced by administering paracetamol (750 mg/kg body weight, single dose intraperitoneal) into one group (group P) of rats. Propylene glycol (vehicle) was administered (2 ml) into another group (group V) of rats. 4 groups of P. niruri extract-pretreated (200 mg/kg body weight/day for 7 days) rats were administered the same single dose of paracetamol on the 7th day. Extract of P. niruri were obtained through ethanol (E), hexane (H), dichloromethane (D) and butane (B). Rat groups were V, P, E + P, H + P, D + P and B + P. Each group consisted of 6 rats and were sacrificed on the 9th day. Parameters for evaluation were biochemical (serum ALT, serum AST, serum ALP, serum bilirubin), hepatic reduced glutathione concentrations and hepatic histology. Propylene glycol (group V) appeared non-toxic to the liver while significant degrees of centrilobuler hepatotoxicity was observed in group P paracetamol-treated rats. The E + P group suggested significant improvements in the serum parameters but these parameters appeared better alleviated in the H + P group. Hepatic reduced glutathione concentrations were replenished to the control level in both E + P and H + P groups. Hepatic histology supported biochemical and other observations in the P, E + P and H + P groups. Lesser degrees of alleviations were observed in the D + P and B + P groups. However, the hexane extract-pretreated group (H + P) appeared to provide the most significant hepatoprotection against paracetamol induced hepatotoxicity in the rat. Titration of the dose following isolation of the active ingredient might offer complete alleviation.

Contribution of Xanthine Oxidase-Derived Oxygen Free Radicals to the Development of Carbon Tetrachloride-Induced Acute Liver Injury in Rats

We examined how oxygen free radicals derived from xanthine oxidase (XOD) contribute to the development of carbon tetrachloride (CCl4)-induced acute liver injury in rats. In rats treated with CCl4 (1ml/kg), liver injury appeared 3h after the treatment and developed by 24h, judged from the serum levels of transaminases. Hepatic and serum XOD activities and serum uric acid concentration did not change 6h after CCl4 treatment, but they all increased at 12h and further increased at 24h. An increase in the concentration of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, and decreases in reduced glutathione concentration and Cu, Zn-superoxide dismutase (SOD) activity, but not Mn-SOD activity, were observed in the liver at 6h after CCl4 treatment and these changes were further enhanced at 24h. When allopurinol (50mg/kg), an XOD inhibitor, was administered to CCl4-treated rats 6h after CCl4 treatment, liver injury progression was prevented with attenuation of increased hepatic and serum XOD activities, serum uric acid concentration, and hepatic TBARS concentration and decreased hepatic reduced glutathione concentration and Cu, Zn-SOD activity at 24h after CCl4 treatment. These results indicate that XOD-derived oxygen free radicals contribute to the progression of CCl4-induced acute liver injury in rats both by stimulating hepatic lipid peroxidation and by disrupting hepatic antioxidant defense system.

Developmental toxicity of lead-contaminated sediment to mallard ducklings.

Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard (Anas platyrhynchos) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 microg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.

Hepatic damage caused by chronic arsenic toxicity in experimental animals.

Noncirrhotic fibrosis of the liver is common in subjects chronically consuming ground water geologically contaminated with arsenic, but the mechanism of the hepatic fibrosis is not known. Because lipid peroxidation has been implicated in the development of several other forms of hepatic fibrosis, including iron and copper overload, we have explored the roles of oxidative stress and lipid peroxidation in the causation of hepatic fibrosis in a murine model of chronic arsenic toxicity. Male BALB/c mice were given drinking water contaminated with arsenic (3.2 mg/L) or arsenic-free (<0.01 mg/L, control) ad libitum. Mice were sacrificed at 3, 6, 9, 12, and 15 months for examination of hepatic histology and assays of hepatic reduced glutathione content, lipid peroxidation, enzymes of the antioxidant defense system, and membrane-bound sodium/potassium ATPase (Na+/K+ ATPase). After 12 months of arsenic feeding, the liver weights increased significantly as did serum aspartate aminotransferase and alanine aminotransferase. After 6 months of arsenic feeding, hepatic glutathione and the enzymes glucose-6-phosphate dehydrogenase and glutathione peroxidase were significantly lower than those of the control group. Hepatic catalase activity was significantly reduced at 9 months in the arsenic-fed group, while glutathione-S-transferase and glutathione reductase activities were also significantly reduced at 12 and 15 months. Plasma membrane Na+/K+ ATPase activity was reduced after 6 months while lipid peroxidation increased significantly after 6 months of arsenic feeding. Liver histology remained normal for the first 9 months, but showed fatty infiltration after 12 months of arsenic feeding. Histologic evidence of fibrosis was observed after 15 months. We have demonstrated hepatic fibrosis due to long-term arsenic toxicity in an animal model. Initial biochemical evidence of hepatic membrane damage, probably due to reduction of glutathione and antioxidant enzymes, may be seen by 6 months. Continued arsenic feeding resulted in fatty liver with serum aminotransferase and alanine aminotransferase elevated at 12 months and hepatic fibrosis at 15 months. The murine model is proposed as relevant to epidemic human toxicity in areas of arsenic contamination.

Potentiation of carbon tetrachloride-induced liver damage by dibutylyl-3',5'-cyclic AMP in unstarved rats.

It has been reported that carbon tetrachloride-induced liver damage is potentiated by starvation partly due to fat accumulation in the liver and a decrease in hepatic reduced glutathione concentration and that dibutylyl-3',5'-cyclic AMP (DBcAMP) affects fuel metabolism and decreases hepatic reduced glutathione. We investigated the effects of DBcAMP on carbon tetrachloride-induced liver damage both in unstarved and starved rats. In unstarved rats, intraperitoneal administration of DBcAMP potentiated an increase in serum alanine aminotransferase activity and fatty vacuolization in the liver, both of which were induced by carbon tetrachloride. Hepatic reduced glutathione concentration was also reduced by DBcAMP, although the change was not significant. In contrast, the administration of DBcAMP in starved rats did not affect carbon tetrachloride-induced changes in serum alanine aminotransferase activity, histological alterations and hepatic reduced glutathione concentration. Administration of DBcAMP to control rats induced different responses in unstarved control rats compared with starved control rats: in unstarved rats, blood glucose concentration decreased but serum free fatty acid concentration increased, whereas in starved rats, blood glucose concentration increased and serum free fatty acid concentration decreased. It was suggested that DBcAMP potentiated carbon tetrachloride-induced liver damage in unstarved rats, probably due to hepatic fat accumulation and a decreased hepatic reduced glutathione concentration. The former could increase the affinity of the liver for carbon tetrachloride and the latter could accelerate carbon tetrachloride-induced lipid peroxidation. It was also suggested that DBcAMP failed to affect carbon tetrachloride-induced liver damage in starved rats, probably because starvation had already decreased hepatic glutathione concentration and DBcAMP had different effects on fuel metabolism compared with effects observed in unstarved rats.

Eicosapentaenoic acid at hypotriglyceridemic dose enhances the hepatic antioxidant defense in mice

The effect of oral administration of purified (95%) eicosapentaenoic acid on serum lipids, hepatic peroxisomal enzymes, antioxidant enzymes and lipid peroxidation was compared with that of palmitic acid fed mice and corresponding controls. After 10 d, a dose of 1000 mg eicosapentaenoic acid per day/kg body weight lowered serum triglycerides by 45%, while no significant change in serum cholesterol level was noted in comparison to palmitic acid fed mice and controls. Hepatic acyl-CoA oxidase and catalase activities increased by 50% and 30%, respectively, in the eicosapentaenoic acid fed group. In addition, the hepatic reduced glutathione content and the activities of glutathione transferase, glutathione peroxidase and glutathione reductase, increased significantly during eicosapentaenoic acid treatment. The levels of hepatic lipid peroxides were lower after eicosapentaenoic acid feeding, while no significant change was noted in the palmitic acid fed mice when compared to the controls. Taken together, the present data demonstrate for the first time that at hypolipidemic doses eicosapentaenoic acid feeding i) enhances the hepatic antioxidant defense, and ii) does not cause a significant differential induction of the two peroxisomal enzymes, acyl-CoA oxidase and catalase, as was noted after administration of hypolipidemic peroxisome proliferating compounds, such as clofibrate in rodents.

Oxidant, mixed-function oxidase and peroxisomal responses in channel catfish exposed to a bleached kraft mill effluent

Channel catfish (Ictalarus punctatus) were exposed to 0, 10, 20, and 40% bleached kraft pulp and paper mill effluent (BKME) for up to two weeks. Fish were sacrificed on days 1, 3, 7, and 14 of exposure. Blood, liver, and gill tissues were assayed for biochemical responses associated with oxidative stress (superoxide dismutase, catalase, and glutathione peroxidase activities and methemoglobin, reduced glutathione, and malondialdehyde concentrations), peroxisome proliferation (palmitoyl-CoA oxidase and lauroyl-CoA oxidase activities) and the mixed-function oxidase system (cytochrome P-450 difference spectra and ethoxyresorufin O-deethylase activities). There were significant dose-related increases in hepatic catalase and ethoxyresorufin O-deethylase activities and significant decreases in hepatic reduced glutathione concentrations. There were also significant increases in lauroyl-CoA oxidase and palmitoyl-CoA oxidases activities, both components of the fatty acid beta-oxidation system and located in peroxisomes. No statistically significant changes were seen in the other components studied. The increases in catalase and the fatty-acid oxidase activities suggest that BKME exposure may have resulted in peroxisome proliferation in catfish hepatic tissue.

Cocaine Hepatotoxicity in Mice: Histologic and Enzymatic Studies

The severity of hepatotoxicity in CF-1 mice given 5 daily doses of 5, 10, and 20 mg cocaine/kg body weight and sacrificed 24 hr after the last injection appeared to be dose-dependent. Using light microscopy, the hallmark of cocaine early toxicity was manifested by pallor and ballooning of the hepatocytes in the midzonal and then in the centrilobular areas. Degeneration and necrosis of the liver cells in the same zones were encountered while the hepatocytes in the periportal areas remained intact. When examined under the electron microscope, such pallor and ballooning of the hepatocytes appeared to to be due to dilation of the rough endoplasmic reticulum (RER) profiles which often revealed a significant loss of their ribosomes. Dilation of the smooth endoplasmic reticulum (SER) was also common and moderate proliferation of peroxisomes was frequently seen. In the degenerating hepatocytes, the 2 forms of endoplasmic reticulum were difficult to recognize and the peroxisomes appeared sparse. Cocaine treatment elevated the level of glutamic pyruvic transaminase and glutamic oxaloacetic transaminase in a dose-dependent manner. Although hepatic cytochrome P450 was slightly increased in the low dose groups, a reduction in the enzyme activity was noticed in the group treated with 20 mg cocaine/kg. However, hepatic reduced glutathione content manifested a significant increase in the group which received 20 mg cocaine/kg.