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

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

Bansal AK ，Bansal M ，Soni G ，Bhatnagar D ... -  《CHEMICO-BIOLOGICAL INTERACTIONS》

Modulation of N-nitrosodiethylamine (NDEA) induced oxidative stress by vitamin E in rat erythrocytes.

Nitrosamines, such as N-nitrosodiethylamine (NDEA), induced oxidative stress due to the generation of reactive oxygen species, which are capable of initiating peroxidative damage to the cell. The present study was designed to establish whether pre-treatment with vitamin E (40 mg/kg body wt, intraperitoneally (ip), twice a week for 4 weeks) to NDEA induced rats provides protection against oxidative stress caused by NDEA. A single necrogenic dose of NDEA (200 mg/kg body wt) was administered intraperitoneally (ip) to the rats with or without vitamin E pre-treatment and the animals were sacrificed on Day 7, 14 or 21 after NDEA administration. Lipid peroxidation (LPO) and the activities of antioxidant enzymes were determined in erythrocytes as indices of oxidative damage. The result showed elevated levels of LPO in erythrocytes with NDEA treatment, however, vitamin E pre-treated rats administered NDEA showed decreased LPO (Day 14 and 21). Superoxide dismutase (SOD) enzyme activity and the glutathione (GSH) content increased with NDEA treatment and remained high in vitamin E pre-treated group. Catalase (CAT), glutathione reductase (GSH-R) and glutathione-S-transferase (GST) enzyme activities declined with NDEA treatment; however, vitamin E pre-treated rats administered NDEA, showed elevation in the enzyme activities. Glutathione peroxidase (GSH-Px) activity increased in erythrocytes in vitamin E pre-treated rats administered NDEA, while Se-GSH-Px activity was not affected significantly. This study demonstrates that the pre-treatment with vitamin E prior to the administration of NDEA was effective in counteracting and modulating oxidative stress in rat erythrocytes in a time-dependent manner.

Bansal AK ，Bansal M ，Soni G ，Bhatnagar D ... -  《HUMAN & EXPERIMENTAL TOXICOLOGY》

Antioxidant potential of thyme extract: alleviation of N-nitrosodiethylamine-induced oxidative stress.

Protective role of thyme extract against N-nitrosodiethylamine (NDEA)-induced oxidative stress has been evaluated in albino rats. For this, one group of rats were fed diet supplemented with thyme extract (0.5%) and served as the test group, whereas animals of the other group fed on normal diet served as the control group. The rats were fed on respective diets for a period of 2 weeks after which stress was induced to half the animals of each group by i.p. administration of NDEA at 200 mg/kg body weight. Animals were killed 48 h post stress-induction period. Feed intake and body weight decreased significantly in both test and control groups, the effect being less in test group. Increase in osmotic fragility and in-vitro lipid peroxidation (LPO) on stress induction was of lower degree in the test group. NDEA toxicity was mainly reflected in liver as evidenced by increased activities of plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. The effect was of lower degree in test group as compared with that in the control group. Increase in urea levels observed following NDEA administration was also of lower degree in test groups. Blood glutathione (GSH) levels increased more so in test group compared with control group on stress induction. The activities of superoxide dismutase (SOD), peroxidase (Px), and catalase (CAT) activities decreased significantly on stress induction in erythrocytes. LPO increased in all the tissues through varying degree, and the increase was appreciably of lower degree in test group. The activity of SOD increased significantly in both test and control group on stress induction, whereas activities of Px and CAT decreased following NDEA treatment, and the effects were of lower degree in test group. Thus, supplementation of diet with thyme extract can improve antioxygenic potential and hence help to prevent oxidative stress.

Rana P ，Soni G 《HUMAN & EXPERIMENTAL TOXICOLOGY》

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

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

Bansal AK ，Trivedi R ，Soni GL ，Bhatnagar D ... -  《INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY》

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

Chemopreventive potential of Acacia nilotica bark extract (ANBE) against single intraperitoneal injection of N-nitrosodiethylamine (NDEA, 200mg/kg) followed by weekly subcutaneous injections of carbon tetrachloride (CCl(4), 3 ml/kg) for 6 weeks induced hepatocellular carcinoma (HCC) in rats was studied. At 45 day after administration of NDEA, 100 and 200mg/kg of ANBE were administered orally once daily for 10 weeks. The levels of liver injury and liver cancer markers such as alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (gamma-GT), total bilirubin level (TBL), alpha-feto protein (AFP) and carcinoembryonic antigen (CEA) were substantially increased following NDEA treatment. However, ANBE treatment reduced liver injury and restored liver cancer markers. ANBE also significantly prevented hepatic malondialdehyde (MDA) formation and reduced glutathione (GSH) in NDEA-treated rats which was dose dependent. Additionally, ANBE also increased the activities of antioxidant enzymes viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) in the liver of NDEA-administered rats. Eventually, ANBE also significantly improved body weight and prevented increase of relative liver weight due to NDEA treatment. Histological observations of liver tissues too correlated with the biochemical observations. HPLC analysis of ANBE showed the presence of gallic, protocatechuic, caffeic and ellagic acids, and also quercetin in ANBE. The results strongly support that A. nilotica bark prevents lipid peroxidation (LPO) and promote the enzymatic and non-enzymatic antioxidant defense system during NDEA-induced hepatocarcinogenesis which might be due to activities like scavenging of oxy radicals by the phytomolecules in ANBE.

Singh BN ，Singh BR ，Sarma BK ，Singh HB ... -  《-》