Chronic hyperhomocysteinemia alters antioxidant defenses and increases DNA damage in brain and blood of rats: protective effect of folic acid

We have previously demonstrated that acute hyperhomocysteinemia induces oxidative stress in rat brain. In the present study, we initially investigated the effect of chronic hyperhomocysteinemia on some parameters of oxidative damage, namely total radical-trapping antioxidant potential and activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), as well as on DNA damage in parietal cortex and blood of rats. We also evaluated the effect of folic acid on biochemical alterations elicited by hyperhomocysteinemia. Wistar rats received daily subcutaneous injection of Hcy (0.3-0.6 micromol/g body weight), and/or folic acid (0.011 micromol/g body weight) from their 6th to their 28th day of life. Twelve hours after the last injection the rats were sacrificed, parietal cortex and total blood was collected. Results showed that chronic homocysteine administration increased DNA damage, evaluated by comet assay, and disrupted antioxidant defenses (enzymatic and non-enzymatic) in parietal cortex and blood/plasma. Folic acid concurrent administration prevented homocysteine effects, possibly by its antioxidant and DNA stability maintenance properties. If confirmed in human beings, our results could propose that the supplementation of folic acid can be used as an adjuvant therapy in disorders that accumulate homocysteine.     

Chronic administration of an organophosphorus insecticide to rats alters cholinergic muscarinic receptors in the pancreas

Male rats were treated for 10 days with the organophosphorus insecticide, acetylcholinesterase inhibitor, O,O-diethyl S-[2-(ethylthio)ethyl]phosphorodithioate (disulfoton, 2 mg/kg/day by gavage). At the end of the treatment, binding of [³H]quinuclidinyl benzilate ([³H]QNB) to cholinergic muscarinic receptors and cholinesterase (ChE) activity were assayed in the pancreas. Functional activity of pancreatic muscarinic receptor was investigated by determining carbachol-stimulated secretion of α-amylase in vitro. ChE activity and [³H]QNB binding were significantly decreased in the pancreas from disulfoton-treated rats. The alteration of [³H]QNB binding was due to a decrease in muscarinic receptor density with no change in the affinity. Basal secretion of amylase from pancreas in vitro was not altered, but carbachol-stimulated secretion was decreased. The effect appeared to be specific since pancreozymin was able to induce the same amylase release from pancreases of control and treated rats. The results suggest that repeated exposures to sublethal doses of an organophosphorus insecticide lead to a biochemical and functional alteration of cholinergic muscarinic receptors in the pancreas.     

Prooxidant and antioxidant activity of blood plasma and histology of internal organs of rats after intravenous administration of magnetite nanoparticles

The effect of a single and multiple intravenous injections of a nanosized magnetite suspension on total prooxidant and antioxidant activity of blood plasma has been investigated by the method of luminoldependent chemoluminescence. Nanoparticles of magnetite exhibited dose-dependent prooxidant properties due to their iron atoms and cause a compensatory activation of antioxidant systems in the rat blood plasma. After a single intravenous administration of magnetite the studied parameters of blood plasma returned to the normal level by the end of the experiment due to elimination of the nanoparticles from the body. In the case of multiple administration of the magnetite suspension the dose-dependent changes in the pro- and antioxidant plasma activity persisted during the whole experiment. Accumulation of magnetite particles in the cells of the rat mononuclear phagocytic system, liver, lungs and kidneys is associated with hemodynamic disorders, local dystrophic and necrotic changes in the parenchyma of these organs. After a single intravenous injection nanoparticles of magnetite are detected in the rat organs for 40 days, but their number decreases by the end of the experiment.     

Sulphadoxine-pyrimethamine alters the antioxidant defense system in blood of rabbit

Sulphadoxine-pyrimethamine (SP) despite reported resistance remains an important drug of choice for the treatment and control of malaria in most endemic areas. Exacerbation of intra-erythrocytic oxidative stress might contribute to the process of elimination of malaria parasites in the body. The effect of treatment with SP on the antioxidant defense system was investigated using rabbit as a model. Ten male rabbits were divided into two groups of five animals each. The first group was administered with normal saline and served as control. The second group received a single dose of SP (26.25mg/kg body weight). Blood samples were collected before and at 6, 12 and 24 h after drug administration. Activity of cellular enzymatic antioxidants, superoxide dismutase (SOD) and catalase (CAT), and level of reduced glutathione (GSH) were assayed using standard spectrophotometric methods. Serum lipid peroxidation was assessed by the formation of thiobarbituric acid reactive species (TBARS) while protein content was assayed by the method of Lowry et al., 1951. SOD activity was observed to increase progressively by 4.9, 63.4 and 120.8% at 6, 12 and 24 h respectively, after drug administration. Similarly, CAT activity increased by 44.5, 82.6 and 116.3% at 6, 12 and 24 h, respectively. TBARS level also increased significantly by 45.5, 118.2 and 186.4%, respectively. However, the level of GSH decreased by 41.9% at 6 h and remained so up till the 12 h, but by 24 h after drug administration, the level of the thiol substance has increased considerably up to 48.4% above the baseline level. SP treatment altered the antioxidant defense system in blood and may therefore induce oxidative stress by generating reactive oxygen species. This might play significant role in the therapeutic and adverse effects associated with the drug.     

Physical activity alters antioxidant status in exercising elderly subjects

Nutritional adequacy and physical activity are two aspects of a health-promoting lifestyle. Not much is known about antioxidant nutrient requirements for exercising elderly (EE) subjects. The question of whether exercise training alters the status of antioxidant vitamins as well as trace elements in elderly subjects and fails to balance the age-related increase in oxidative stress is addressed in this study. There were 18 EE (68.1+/-3.1 years), 7 sedentary elderly (SE; 70.4+/-5.0 years), 17 exercising young (EY; 31.2+/-7.1 years) and 8 sedentary young (SY; 27.1+/-5.8 years) subjects who completed 7-day food and activity records. Each subject's blood was sampled on Day 8. A similar selenium (Se) status but a higher erythrocyte glutathione peroxidase (GSH-Px) activity were found in EE subjects as compared with EY and SE subjects. Blood oxidized glutathione was higher and plasma total thiol was lower in EE subjects as compared with EY subjects. Mean vitamin C (167 vs. 106 mg/day), vitamin E (11.7 vs. 8.3 mg/day) and beta-carotene (4 vs. 2.4 mg/day) intakes were higher in EE subjects as compared with EY subjects. However, EE subjects exhibited the lowest plasma carotenoid concentrations, especially in beta-carotene, which was not related to intakes. Despite high intakes of antioxidant micronutrients, no adaptive mechanism able to counteract the increased oxidative stress in aging was found in EE subjects. Results on GSH-Px activity illustrate that the nature of the regulation of this biomarker of Se status is different in response to training and aging. These data also strongly suggest specific antioxidant requirements for athletes with advancing age, with a special attention to carotenoids.     

Effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity in rats

In order to find out the effect of chronic ethanol administration on testicular antioxidant system and steroidogenic enzyme activity, male rats fed with ethanol 1.6g/kg body weight per day for four weeks were studied. Besides a drastic reduction in body and testis weight, there was decrease in ascorbic acid, reduced glutathione and activities of superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase in the testicular tissue of the treated animals. Simultaneously, there was increase in lipid peroxidation and glutathione S-transferase activity. Activities of 3 beta-hydroxy steroid dehydrogenase and 17 beta-hydroxy steroid dehydrogenase were also found decreased in the treated animals. The results indicate that chronic ethanol administration resulted in increase in oxidative stress and decrease in the activities of steroidogenic enzymes in the rat testes.     

Effects of chronic administration of doxorubicin on myocardial creatine phosphokinase and antioxidant defenses and levels of lipid peroxidation in tissues and plasma of rats

Tissue and plasma levels of thiobarbituric acid reactive substances (TBARS) were measured in rats treated chronically with doxorubicin. In addition, heart creatine phosphokinase and antioxidant defenses were examined. Male rats received doxorubicin (DXR) 2 mg/kg or vehicle weekly subcutaneously for 13 weeks and were sacrificed at 14 and 19 weeks, 1 and 6 weeks after the last dose, respectively. Histological evaluation in DXR-treated rats at 14 and 19 weeks found significant and progressive cardiac and renal lesions as compared to controls. Heart TBARS were unchanged from controls. Plasma and kidney levels of TBARS were elevated above controls at both 14 and 19 weeks. Lung levels of TBARS were significantly elevated above controls at 14 weeks. Liver levels of TBARS were elevated at 19 weeks. Heart creatine phosphokinase activity was significantly depressed from controls at both 14 and 19 weeks. Heart glutathione peroxidase and superoxide dismutase activities were unchanged from controls. Heart glutathione, glutathione reductase, glucose-6-phosphate dehydrogenase, and catalase were elevated above controls at both 14 and 19 weeks. The lack of change in heart TBARS suggests that changes in TBARS in other organs may be secondary processes. The depression of creatine phosphokinase suggests that levels of adenosine triphosphate may be insufficient to sustain the myocardial function and this may partly be responsible for DXR-induced cardiac myopathy.     

High dietary salt decreases antioxidant defenses in the liver of fructose-fed insulin-resistant rats

In this study we investigated the hypothesis that a high-salt diet to hyperinsulinemic rats might impair antioxidant defense owing to its involvement in the activation of sodium reabsorption to lead to higher oxidative stress. Rats were fed a standard (CON), a high-salt (HS), or a high-fructose (HF) diet for 10 weeks after which, 50% of the animals belonging to the HF group were switched to a regimen of high-fructose and high-salt diet (HFS) for 10 more weeks, while the other groups were fed with their respective diets. Animals were then euthanized and their blood and liver were examined. Fasting plasma glucose was found to be significantly higher (approximately 50%) in fructose-fed rats than in the control and HS rats, whereas fat liver also differed in these animals, producing steatosis. Feeding fructose-fed rats with the high-salt diet triggered hyperinsulinemia and lowered insulin sensitivity, which led to increased levels of serum sodium compared to the HS group. This resulted in membrane perturbation, which in the presence of steatosis potentially enhanced hepatic lipid peroxidation, thereby decreasing the level of antioxidant defenses, as shown by GSH/GSSG ratio (HFS rats, 7.098±2.1 versus CON rats, 13.2±6.1) and superoxide dismutase (HFS rats, 2.1±0.05 versus CON rats, 2.3±0.1%), and catalase (HFS rats, 526.6±88.6 versus CON rats, 745.8±228.7 U/mg ptn) activities. Our results indicate that consumption of a salt-rich diet by insulin-resistant rats may lead to regulation of sodium reabsorption, worsening hepatic lipid peroxidation associated with impaired antioxidant defenses.     

Superoxide elimination activity and the transferrin-ceruloplasmin antioxidant system in the blood serum in chronic emotional-pain stress and the administration of dimethyl sulfoxide in rats

The influence of emotional painful stress (EPS) and dimethyl sulfoxide (DMSO) treatment on ceruloplasmin-transferrin (Cp-Tr) antioxidant system and superoxide dismutase-like activity (SODLA) of the rat serum was studied. No changes in Cp-Tr and SODLA were observed in EPS. On the contrary, DMSO treatment was followed by a decrease in Cp-Tr activity and an increase in SODLA. It is suggested that Cp-Tr and SODLA systems are two interacting antioxidant systems of the serum.     

Weak antioxidant defenses make the heart a target for damage in copper-deficient rats

Copper deficiency causes more salient pathologic changes in the heart than in the liver of rats. Although oxidative stress has been implicated in copper deficiency-induced pathogenesis, little is known about the selective toxicity to the heart. Therefore, we examined the relationship between the severity of copper deficiency-induced oxidative damage and the capacity of antioxidant defense in heart and liver to investigate a possible mechanism for the selective cardiotoxicity. Weanling rats were fed a purified diet deficient in copper (0.4 μg/g diet) or one containing adequate copper (6.0 μg/g diet) for 4 weeks. Copper deficiency induced a 2-fold increase in lipid peroxidation in the heart (thiobarbituric assay) but did not alter peroxidation in the liver. The antioxidant enzymatic activities of superoxide dismutase, catalase, and glutathione peroxidase were, respectively, 3-, 50- and 1.5-fold lower in the heart than in the liver, although these enzymatic activities were depressed in both organs by copper deficiency. In addition, the activity of glutathione reductase was 4 times lower in the heart than in the liver. The data suggest that a weak antioxidant defense system in the heart is responsible for the relatively high degree of oxidative damage in copper-deficient hearts.     

Chronic cadmium-ethanol administration alters metal distribution and some biochemicals in rat brain

The effects of cadmium (100 ppm through drinking water) and ethanol (5 g/kg by gastric gavage) administration on biogenic amines, metal distribution and certain enzymes in rat brain was investigated after 90 days of exposure. Co-exposure group revealed significant accumulation of cadmium and also increase in zinc levels compared to all the other groups. Ethanol alone decreased MAO activity and increased NE and 5-HT level while in combination with Cd, these effects were more magnified. It is, therefore, suggested that the persons consuming alcohol may be more prone to the neurotoxic effects of this metal.     

Oxidative stress and antioxidant defenses in pregnant women

Abstract

Objectives

Oxidative stress (OS) is defined as an imbalance in the production of reactive oxygen species and the capacity of antioxidant defenses. The objective of this work was to investigate OS and antioxidant capacity in pregnant women.

Methods

Parameters of the oxidative status and antioxidant capacity in serum and whole blood were evaluated in thirty-nine women with normal pregnancy.

Results

The assessment of antioxidants indicated an increase in superoxide dismutase and catalase activities (P < 0.05 and P < 0.01) and a decrease in ascorbic acid levels and the total content of sulfhydryl (P < 0.05 and P < 0.001). Additionally, when the pro-oxidant system was investigated we found an increase (P < 0.01) in malondialdehyde and no significant change (P > 0.05) in protein carbonylation.

Discussion

This study demonstrates that there is a change in the pro-oxidant and antioxidant defenses associated with body and circulation changes that are inherent to the pregnancy process.     

Uteroplacental insufficiency alters hepatic fatty acid-metabolizing enzymes in juvenile and adult rats

Multiple adult morbidities are associated with intrauterine growth retardation (IUGR) including dyslipidemia. We hypothesized that uteroplacental insufficiency and subsequent IUGR in the rat would lead to altered hepatic fatty acid metabolism. To test this hypothesis, we quantified hepatic mRNA levels of acetyl-CoA carboxylase (ACC), carnitine palmitoyltransferase (CPTI), the beta-oxidation-trifunctional protein (HADH), fasting serum triglycerides, and hepatic malonyl-CoA levels at different ages in control and IUGR rats. Fetal gene expression of all three enzymes was decreased. Juvenile gene expression of CPTI and HADH continued to be decreased, whereas gene expression of ACC was increased. Serum triglycerides were unchanged. A sex-specific response was noted in the adult rats. In males, serum triglycerides, hepatic malonyl-CoA levels, and ACC mRNA levels were significantly increased, and CPTI and HADH mRNA levels were significantly decreased. In contrast, the female rats demonstrated no significant changes in these variables. These results suggest that uteroplacental insufficiency leads to altered hepatic fatty acid metabolism that may contribute to the adult dyslipidemia associated with low birth weight.     

Chronic ethanol consumption alters cardiovascular functions in conscious rats

Chronic ethanol intake and hypertension are related. In the present work, we investigated the effect of chronic ethanol (20% v/v) intake for 2, 6 and 10 weeks on basal arterial blood pressure, baroreflex and heart rate levels, as well as on the cardiovascular responses to the infusion of vasoactive agents in unanesthetized rats. Mild hypertension was observed after 2 weeks, 6 weeks or 10 weeks of treatment. On the other hand, no changes were observed in heart rate after long-term ethanol intake. Similar baroreflex changes were observed in 2- or 6-week ethanol-treated rats, and affected all parameters of baroreflex sigmoid curves, when compared to the control group. These changes were characterized by an enhanced baroreflex sympathetic component and a reduction in the baroreflex parasympathetic component. No differences in baroreflex parameters were observed in 10-week ethanol-treated animals. The pressor effects of i.v. phenylephrine were enhanced in 2-week ethanol-treated rats; not affected in 6-week treated animals and reduced in 10-week ethanol-treated rats, when compared to respective control and isocaloric groups. The hypotensive response to i.v. sodium nitroprusside (SNP) was enhanced at all different times of treatment, when compared to respective control and isocaloric groups. In conclusion, the present findings showed increased arterial pressure in the early phase of chronic ethanol consumption, which was consequent of rise in both systolic and diastolic pressures. Ethanol intake affected both the sympathetic and the parasympathetic components of the baroreflex. Vascular responsiveness to the pressor agent phenylephrine was initially enhanced and later on decreased during chronic ethanol intake. Vascular responsiveness to the depressor agent SNP was enhanced during chronic ethanol intake.     

Acetylcholinesterase and butyrylcholinesterase activity in the atria of the heart of adult albino rats

In experiments on adult albino rats the authors used the substances BW 284 C51 (1.5-bis(allyldimethylammoniumphenyl)-pentane-3-one-dibromide) as a specific inhibitor of acetylcholinesterase (AChE) and ethopropazine (10-(2-diethylaminopropyl) phenothiazine hydrochloride) as a specific inhibitor of butyrylcholinesterase (BuChE) to determine the two enzyme activities in atrial homogenates and to investigate changes after AChE or BuChE inhibition of the negative chronotropic effect of acetylcholine (ACh) on atria incubated in vitro. AChE accounted for only 12% and BuChE for 88% of the total ability of atrial homogenates to hydrolyse acetylcholine. The concentration of exogenous ACh needed to reduce the spontaneous frequency of contractions of the isolated right atrium by 30, 60, or 90/min fell by 78%, 79% and 84% respectively after BW 284 C51 inhibition of AChE and by 95%, 94% and 94% after simultaneous inhibition of AChE and BuChE. The significance of AChE in control of the negative chronotropic effect of ACh is thus evidently significantly greater than would correspond to the percentual proportion of AChE in cholinesterase activities in the atria of the rat heart. In can be assumed that AChE is functionally associated with parasympathetic innervation of the heart and that it is probably present in a high concentration in the primary pacemaker region.     

Generation of blood anticoagulant and fibrinolytic activity after intravenous administration of protein C-a in rats

Protein C--vitamin K-dependent protein of the blood coagulation system possessing anticoagulant and fibrinolytic activities was under investigation. Activated partial thromboplastin time was shown to prolong to 214 +/- 8.9% from the first minute after intravenous administration of 0.51 mg per rat bovine protein Ca. After 5 minutes the activity of plasminogen activators increased to 339 +/- 52.8%. Both effects gradually diminished and came back to the starting level within 60-90 minutes. The factor V activity reduced two-fold and didn't return to basal level. We propose that protein Ca reveals its enzymatic activity within first minutes after administration and is blocked then with its inhibitor.     

Lipid peroxidation and antielastase activity in the lung under oxidant stress: role of antioxidant defenses

The role of lipid peroxidation in the inactivation of alpha 1-protease inhibitor (alpha 1-PI) in the alveolar lining fluid of human subjects has been examined under oxidant stress. Exposure to nitrogen dioxide (NO2) at 4 ppm for 3 h resulted in a significant increase in the amount of lipid peroxidation products in the alveolar lining fluid, with conjugated dienes the predominant species. Four-week supplementation with vitamins C and E before NO2 exposure markedly decreased the levels of conjugated dienes (control 804 +/- 103 pmol/micrograms total phospholipids vs. vitamin-supplemented 369 +/- 58, P = 0.003). Malondialdehydes, although detectable in the lavage fluid, contributed little to the total amount of lipid peroxidation products, and the levels were comparable in both groups. NO2 exposure in the absence of vitamin supplementation caused a significant decrease in the elastase inhibitory capacity (EIC) of the alveolar lining fluid in the control group but not in the vitamin-supplemented group [control 3.67 +/- 0.32 micrograms alpha 1-PI/micrograms porcine pancreatic elastase (PPE) vs. vitamin-supplemented 2.75 +/- 0.17, P less than 0.03]. The vitamin-supplemented group had a lower level of conjugated dienes and a higher EIC. Conversely, the control group had higher levels of conjugated dienes and a lower EIC in their lavage fluid. These studies demonstrate that lipid peroxidation occurs as an early event during oxidant exposure in the lungs of normal subjects. The appearance of lipid peroxidation products in the lavage fluid is associated with a decrease in the EIC of the alveolar lining fluid. Vitamins C and E diminish lipid peroxidation and preserve the EIC of the lower respiratory tract fluid during oxidant stress.     

Nippostrongylus brasiliensis: Infection decreases plasma butyrylcholinesterase activity in rats

Plasma butyrylcholinesterase (BChE) hydrolyzes ester-containing compounds such as succinylcholine, as well as acting as a scavenger against neurotoxic organophosphates (OPs). We previously found that Nippostrongylus brasiliensis infection makes rats more susceptible to OP toxicity by decreasing serum paraoxonase-1 (PON1) activity. In the present study, we examined the effects of N.brasiliensis infection on acetylcholinesterase (AChE) activity in plasma, red blood cells (RBCs), brain and diaphragm, as well as serum PON1 activity, in rats at day 7 after infection. N.brasiliensis infection significantly decreased plasma BChE and PON1 activities without significantly altering AChE activity in RBCs, brain and diaphragm. These results provide further insight into the unusual deleterious effects of intestinal nematode infections on body homeostasis.