Satu M. Somani

CHRONIC ETHANOL AND NICOTINE INTERACTION ON RAT TISSUE ANTIOXIDANT DEFENSE SYSTEM

Ethanol consumption and cigarette smoking are common in societies worldwide and have been identified as injurious to human health. This study was undertaken to examine the interactive effects of chronic ethanol and nicotine consumption on the antioxidant defense system in different tissues of rat. Male Fisher-344 rats were divided into four groups of five animals each and treated for 6.5 weeks as follows: (1) Control rats were administered normal saline orally; (2) ethanol (20% [wt./vol.]) was given orally at a dose of 2 g/kg; (3) nicotine was administered subcutaneously at a dose of 0.1 mg/kg; and (4) a combination of ethanol plus nicotine was administered by the route and at the dose described above. The animals were killed 20 h after the last treatment, and liver, lung, kidney, and testes were isolated and analyzed. Chronic ingestion of ethanol resulted in a significant depletion of glutathione (GSH) content in liver, lung, and testes, whereas chronic administration of nicotine significantly depleted GSH content in liver and testes. The combination of ethanol plus nicotine resulted in a significant depletion of GSH content in liver, lung, and testes. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly increased superoxide dismutase (SOD) activity in liver and decreased SOD activity in kidney. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly decreased catalase (CAT) activity in liver and increased CAT activity in kidney and testes. Chronic ingestion of ethanol resulted in a significant decrease in glutathione peroxidase (GSH-Px) activity in liver and kidney, whereas a combination of ethanol plus nicotine increased GSH-Px activity in liver and decreased GSH-Px activity in kidney and testes. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly increased lipid peroxidation, respectively, in liver. It is suggested that prolonged exposure to ethanol and nicotine produce similar, and in some cases additive, oxidative tissue injuries in rat.

Dose-Dependent Protection by Lipoic Acid against Cisplatin-Induced Nephrotoxicity in Rats: Antioxidant Defense System

This study was designed to investigate the role of graded doses of lipoic acid pretreatment against cisplatin-induced nephrotoxicity. Male Wistar rats were divided into six groups and treated as follows: 1) vehicle (saline) control; 2) cisplatin (16 mg/kg, intraperitoneally); 3) lipoic acid (100 mg/kg, intraperitoneally); 4) cisplatin plus lipoic acid (25 mg/kg); 5) cisplatin plus lipoic acid (50 mg/kg) and 6) cisplatin plus lipoic acid (100 mg/kg). Rats were sacrificed three days after treatment, and plasma as well as kidneys were isolated and analyzed. Plasma creatinine increased (677% of control) following cisplatin administration alone which was decreased by lipoic acid in a dose-dependent manner. Cisplatin-treated rats showed a depletion of renal glutathione (GSH), increased oxidized GSH and decreased GSH/GSH oxidized ratio (62%, 166% and 62% of control), respectively which were restored with lipoic acid pretreatment. Renal superoxide dismutase, catalase, glutathione peroxidase (GSH peroxidase) and glutathione reductase activities decreased (62%, 75%, 62% and 80% of control), respectively, and malondialdehyde content increased (204% of control) following cisplatin administration, which were restored with increasing doses of lipoic acid. The renal platinum concentration increased following cisplatin administration, which was possibly decreased by chelation with lipoic acid. The data suggest that the graded doses of lipoic acid effectively prevented a decrease in renal antioxidant defense system and prevented an increase in lipid peroxidation, platinum content and plasma creatinine concentrations in a dose-dependent manner.

Application of Antioxidants and Other Agents to Prevent Cisplatin Ototoxicity

Objective/Hypothesis: To review the recent data from experiments performed in this laboratory to test the hypothesis that cisplatin ototoxicity is related to depletion of glutathione and antioxidant enzymes in the cochlea and that the use of antioxidants or protective agents would protect the cochlea against cisplatin damage and prevent hearing loss.

Protection by ebselen against cisplatin-induced nephrotoxicity: Antioxidant system

This study was designed to investigate the cisplatin-induced alteration in renal antioxidant system and the nephroprotection with ebselen. Male Wistar rats were injected with (1) vehicle control; (2) cisplatin; (3) ebselen; and (4) cisplatin plus ebselen. Rats were sacrificed three days post-treatment and plasma as well as kidney were isolated and analyzed. Plasma creatinine increased 598% following cisplatin administration alone which decreased by 158% with ebselen pretreatment. Cisplatin-treated rats showed a depletion of renal glutathione (GSH) levels (52% of control), while cisplatin plus ebselen injected rats had GSH values close to the controls. Antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities decreased 38, 75 and 62% of control, respectively, and malondialdehyde (MDA) levels increased 174% of control following cisplatin administration, which were restored to control levels after ebselen treatment. The renal platinum level did not significantly change with ebselen pretreatment. This study suggests that the protection offered by ebselen against cisplatin-induced nephrotoxicity is partly related to the sparing of antioxidant system.

Dose- and time-dependent effects of ethanol on plasma antioxidant system in rat.

This study investigates the dose- as well as time-dependent effects of ethanol ingestion on antioxidant system and lipid peroxidation in plasma of the rat. The plasma ethanol concentrations were 154+/-18, 231+/-53, and 268+/-49 mg/dl 1 h after oral ethanol doses of 2, 4, and 6 g/kg, respectively. Superoxide dismutase (SOD) (71%, 56%, and 41 % of control) and glutathione reductase (GR) (71%, 66%, and 55% of control) activity in plasma were significantly decreased in a dose-dependent manner. Catalase (CAT)/SOD and glutathione peroxidase (GSH-Px)/SOD ratios were significantly increased whereas GR/GSH-Px ratio was significantly decreased with increasing dose of ethanol. In a time course study, plasma ethanol concentrations were 177+/-9.7, 143+/-11, 99+/-17, and 26+/-11 mg/dl at 1.5, 2, 4, and 6 h after an oral dose (4 g/kg) of ethanol in rat indicating time-dependent elimination of ethanol. Plasma SOD and GSH-Px activity significantly increased 4-6 h whereas GR activity significantly decreased 2-4 h after ethanol ingestion. The ratio of GR/GSH-Px and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in plasma decreased at 1.5-6 h after ethanol ingestion. Plasma malondialdehyde (MDA) levels significantly elevated with respect to an increase in time after ethanol ingestion, indicating time-dependent augmentation of lipid peroxidation. The data indicate that ethanol ingestion perturbs the plasma antioxidant system in a dose- and time-dependent manner. The significant changes in the ratios of CAT/SOD, GSH-Px/SOD, GR/GSH-Px, and GSH/GSSG in plasma may be used as an index of alcohol-induced oxidative stress.

Interaction of exercise and ethanol on antioxidant enzymes in brain regions of the rat

This study investigates the effect of ethanol ingestion on antioxidant enzymes (AOE) and lipid peroxidation (malondialdehyde, (MDA) in different brain regions of the rat after acute exercise. Acute exercise (100% VO2max) significantly increased glutathione peroxidase (GSH-Px) activity and decreased glutathione reductase (GR) activity in the cerebral cortex. Acute exercise significantly increased MDA level in the corpus striatum. Ethanol (20%) (1.6 g/kg, PO) significantly increased MDA level in the cerebral cortex. Ethanol also significantly increased superoxide dismutase (SOD) activity in the cortex and catalase (CAT), GSH-Px, and GR activities in the corpus striatum. Ethanol significantly augmented CAT activity in the medulla and GSH-Px activity in the hypothalamus. However, CAT activity significantly decreased in the hypothalamus after ethanol ingestion. The combination significantly increased GSH-Px activity in the hypothalamus, SOD activity in the cortex, GR activity in the striatum, and MDA level in the medulla. In conclusion, the cerebral cortex, striatum medulla, and hypothalamus reacted differentially in response to ethanol as well as to acute exercise-induced oxidative stress whereas the combination moderated the changes in AOE activity in specific brain regions.

Dose response of ethanol on antioxidant defense system of liver, lung, and kidney in rat

This study investigated the alterations in levels of glutathione, lipid peroxidation, and antioxidant enzyme activity in the liver, lung, and kidney of rats treated with acute doses of ethanol. Male Fisher-344 rats were randomly divided into four groups, and were treated as follows: (1) vehicle (saline) control; (2) ethanol 2 g/kg, p.o.; (3) ethanol 4g/kg, p.o.; and (4) ethanol 6 g/kg, p.o. The animals were sacrificed 1 h after treatment, and tissues were isolated and analyzed. The hepatic GSH levels significantly decreased (73, 68, and 66% of control) due to ethanol ingestion at 2, 4, and 6g/kg, respectively. The hepatic GSH/GSSG ratio also decreased with increasing doses indicating stress response due to ethanol. The hepatic SOD activity significantly decreased (70, 75 and 71% of control) with graded doses of ethanol ingestion. The hepatic CAT/SOD and GSH-Px+CAT/SOD ratios significantly increased (147, 169 and 177% of control) and (140, 167 and 178% of control), respectively with increasing doses of ethanol. In the lung, graded doses of ethanol increased GSH-Px activity (120, 114 and 141% of control) and decreased GR activity (98, 89 and 89% of control), respectively. The MDA concentrations in the lung also increased after higher ethanol ingestion. Most of the antioxidant enzyme ratios increased with increasing doses of ethanol in the lung. In the kidney, GSH-Px activity increased (139, 119 and 151% of control), whereas GR activity decreased (84, 85 and 83% of control). GSH-Px/SOD and GSH-Px+CAT/SOD ratios increased whereas GR/GSH-Px ratio decreased after graded doses of ethanol. GSH levels in the kidney decreased after ethanol ingestion. MDA concentrations increased with increasing dose of ethanol in the kidney. These results showed the dose dependant and tissue specific changes in the antioxidant system after ethanol ingestion. Ethanol exerts oxidative stress on antioxidant systems of liver, lung and kidney in proportion to the amount of ethanol ingestion.

Interaction of exercise training and chronic ethanol ingestion on hepatic and plasma antioxidant system in rat

This study was undertaken in order to investigate the interactive effects of exercise training and chronic ethanol consumption on the antioxidant system in rat liver and plasma. Fisher‐344 rats were treated in separate groups as follows: sedentary control (SC); exercise training (ET) for 6.5 weeks; ethanol 20% (2.0 g kg−1, p.o.) for 6.5 weeks; and ET and ethanol administration. In liver, ET significantly decreased the malondialdehyde (MDA) level (73% of SC). Chronic ethanol significantly increased catalase (CAT) activity and MDA levels (126% and 135% of SC), respectively, and also depleted the reduced glutathione (GSH) level and the reduced to oxidized glutathione (GSH/GSSG) ratio (81% and 38% of SC), respectively. Exercise training plus ethanol significantly increased CAT and glutathione reductase (GR) activity (126% and 118% of SC), respectively, and decreased the MDA level (67% of SC). In plasma, ethanol significantly enhanced CAT activity and MDA levels (173% and 221% of SC), respectively. Ethanol ingestion also increased the CAT/superoxide dismutase (SOD) ratio (216% of SC) in plasma. Training plus ethanol ingestion significantly increased CAT activity and MDA levels (208% and 148% of SC), respectively, and increased CAT/SOD and glutathione peroxidase (GSH‐Px)/SOD ratios (279% and 142% of SC), respectively. The data indicate that the combination of exercise and ethanol ingestion resulted in an enhanced hepatic CAT and GR activity to eliminate H2O2 and to maintain endogenous GSH levels. Thus, training ameliorated the ethanol‐induced oxidative injury in the liver. The ratio of CAT/SOD in plasma increased twofold due to chronic ethanol intake and threefold due to the combination, which may be used as an index of oxidative stress.

Response of cardiac antioxidant system to alcohol and exercise training in the rat

Recent evidence has shown that alcohol as well as exercise induces oxidative stress. However, the combination of both on the cardiac antioxidant system is not known. This study investigates the interactive effects of exercise training and chronic ethanol consumption on the antioxidant system of the rat heart. Male Fisher-344 rats were treated as follows: 1) sedentary control (SC); 2) exercise training (ET) for 6.5 weeks; 3) ethanol (2 g/kg, PO) for 6.5 weeks, and 4) ET plus ethanol for 6.5 weeks. Rats were sacrificed and hearts were isolated. Glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and lipid peroxidation (MDA) were determined in heart tissues. SOD and GSH-Px activities were significantly increased 118% and 148% of SC, respectively, due to ET. GSH level increased 118% of SC in ET rats. GSH-Px activity increased 118% of SC whereas SOD activity and CuZn-SOD protein level and GR activity decreased 87%, 71%, and 90% of SC due to chronic ethanol administration. GSH level decreased 87% of SC and lipid peroxidation increased 149% of SC due to ethanol consumption. GSH-Px activity and GSH levels increased 143% and 130% of SC due to combination of ET and ethanol. This study suggests that ET and chronic ethanol ingestion augments the antioxidant enzyme activity and GSH levels in the heart. This combination reduced the extent of ethanol-induced lipid peroxidation. The data suggest that ET may reduce the extent of the damage caused by ethanol consumption on the myocardium.

Effect of topically applied sulphur mustard on antioxidant enzymes in blood cells and body tissues of rats

The effect of sulphur mustard (0.5 LD50, percutaneous) on antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px)) in blood cells (erythrocytes (RBC), leucocytes (WBC) and platelets) and body tissues (liver, kidney, spleen and brain) of rats has been investigated 24 h post exposure. The SOD activity was significantly decreased in WBC, platelets, spleen and brain as compared to control. The CAT activity was significantly inhibited in RBC, WBC and spleen as compared to control. The GSH‐Px activity was significantly depressed in WBC, spleen and liver as compared to control. It is concluded that sulphur mustard at a sublethal dose inhibited antioxidant enzyme activities in WBC and spleen. Thus, antioxidant enzymes in lymphatic tissues may be used as suitable models for assessing mustard toxicity. The study suggests the formation of reactive oxygen species in sulphur mustard intoxication.