Inhibition of trout (Salmo gairdneri R.) PBG-synthase by some metal ions (Mg2+, Pb2+, Zn2+)

The effect of metal ions on the activity of trout kidney and liver PBG-synthase was investigated. Heavy metals inhibited the kidney enzyme in a complex manner. Kinetic analysis of the inhibition of liver activity by Pb2+ (Ki = 1.3 mM) was consistent with non-competitive inhibition, whereas Zn2+ (Ki = 1.3 mM) and Mg2+ (Ki = 3.5 mM) were competitive inhibitors.     

Effect of L-propargylglycine on metabolism of sulfur-containing amino acids in pregnant rats and their fetuses

Cystathionine accumulated in several tissues of dams and fetuses by a single intraperitoneal administration of L-proparglyglycine to pregnant rats. Cystathionine in the liver of dams reached its maximal level at about 15 hrs after L-proparglyglycine injection (10 mg/300g), while that in the kidney and brain of dams, and in the liver, kidney, and brain of fetuses reached a maximum at about 21 hrs. The content of cystine in the liver of fetuses decreased gradually in proportion to the amount of L-proparglyglycine administered. Cystathionine gamma-lyase activity in the liver of dams and fetuses decreased to about 2-4% of that of control rats at 15 hrs after L-proparglyglycine injection, and that in the kidney and pancreas of dams to about 10-20% of that of control rats. On the other hand, cystathionine beta-synthase activity did not show significant changes from that of control rats.     

Unusual metabolism of sulfur-containing amino acids in rats treated with DL-propargylglycine

S-(2-Hydroxy-2-carboxyethyl)homocysteine, S-(3-hydroxy-3-carboxy-n-propyl)-cysteine, N-acylated S-(beta-carboxyethyl)cysteine, and N-acylated S-(3-hydroxy-3-carboxy-n-propyl) cysteine were excreted in the urine after DL-propargylglycine treatment. Cystathionine was also accumulated in several tissues of DL-propargylglycine-treated rats. N-Monoacetylcystathione was found in the liver of rats and was also detected in the kidney and serum. Cystathionine gamma-lyase activity in liver decreased to about 4% of that of control rats 24 h after the DL-propargylglycine injection, and alanine aminotransferase activity decreased to about 35% of that of control rats. On the other hand, aspartate aminotransferase and cystathionine beta-synthese activity did not show significant changes from those of control rats. The ability of normal tissues to synthesize cystathionine utilizing cystathionine beta-synthase was 1.98 +/- 0.40 mumol/min/g in liver, 0.61 +/- 0.13 in kidney, and 0.18 +/- 0.015 in brain. The maximal contents of cystathionine in rat tissues and the administered amounts of DL-propargylglycine agreed well with the ability to synthesize cystathionine in each tissue.     

Metal constitution of metallothionein influences inhibition of delta-aminolaevulinic acid dehydratase (porphobilinogen synthase) by lead.

This study was undertaken to evaluate the effect of Zn and Cd pretreatment on the inhibition of delta-aminolaevulinic acid dehydratase (ALAD; porphobilinogen synthase, EC 4.2.1.24) by Pb. Male CD rats were pretreated with 200 mumol of Zn/kg s.c. (subcutaneously) or 18 mumol of Cd/kg s.c., 48 and 24 h before assay of ALAD. Pretreatment with Zn resulted in activation of hepatic and renal ALAD and attenuated the inhibition of this enzyme by Pb in vitro. Pretreatment with Cd increased hepatic ALAD activity, and the inhibitory effect of Pb on the hepatic enzyme was attenuated in this group. In contrast with the situation in liver, pretreatment with Cd did not affect the activity of renal ALAD and did not alter the inhibitory effect of Pb on the renal enzyme. The Pb IC50 (concentration causing half-maximal inhibition) values for hepatic and renal ALAD in Zn-pretreated rats and for hepatic ALAD in Cd-pretreated rats were increased above control, whereas the IC50 for renal ALAD in Cd-pretreated rats was unchanged. Cytosolic binding patterns for the three metals were assessed by gel-filtration chromatography and disclosed that 203Pb was co-eluted with Zn and Cd bound to liver and kidney Zn-thioneins and liver Cd,Zn-thionein, although minimal binding of 203Pb to kidney Cd,Zn-thionein was observed. Estimation of the molar ratio of metals bound revealed Cd/Zn ratios of 2 and 5 for Cd,Zn-thioneins from liver and kidney respectively. The inhibition of purified ALAD by Pb was also attenuated by addition of purified Zn-thioneins and Cd,Zn-thioneins from liver and kidney in the following order: liver Zn-thionein = kidney Zn-thionein greater than liver Cd,Zn-thionein much greater than kidney Cd,Zn-thionein. Thus liver and kidney Zn-thioneins and liver Cd,Zn-thionein with a low Cd/Zn ratio readily decrease the free pool of Pb available to interact with ALAD. These data also demonstrate that the capacity of metallothionein to alter the intracellular distribution of Pb and mediate the inhibition of ALAD by Pb is dependent on the tissue source and relative metal constitution of the metallothionein.     

On the metabolism of amygdalin. 2. The distribution of beta-glucosidase activity and orally administered amygdalin in rats

The organs of 15-day-old rats had the highest capability to hydrolyze amygdalin and prunasin, and most of this activity is concentrated in the tissues of the small and large intestines. The activity decreased with age. In adult rats, the ability of the organs to hydrolyze prunasin is higher than that of amygdalin and is concentrated in the spleen, large intestine, and kidney (35.0, 15.0, and 8.9 micrograms prunasin hydrolyzed . h-1 . g tissue-1). Minced tissues of the liver, spleen, kidney, and stomach contain more hydrolytic capability than the homogenate of these organs, while the reverse is the case with the small and large intestines. When 30 mg amygdalin was orally administered to adult rats, its distribution after the 1st h was as follows: stomach (0.89 mg), small intestine (0.78 mg), spleen (0.36 mg), large intestine (0.30 mg), kidney (0.19 mg), liver (0.10 mg), and serum (5.6 micrograms/mL). At the end of the 2nd h, the highest amygdalin content was found in the large intestine (0.79 mg).     

Influence of subacute treatment of some plant growth regulators on serum marker enzymes and erythrocyte and tissue antioxidant defense and lipid peroxidation in rats

This study aims to investigate the effects of the plant growth regulators (PGRs) (2,3,5-triiodobenzoic acid (TIBA), Naphthaleneacetic acid (NAA), and 2,4-dichlorofenoxyacetic acid (2,4-D)) on serum marker enzymes (aspartate aminotransferase (AST), alanin aminotransferase (ALT), creatine phosphokinase (CPK), and lactate dehydrogenase (LDH)), antioxidant defense systems (reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase (GST), and catalase (CAT)), and lipid peroxidation content (malondialdehyde = MDA) in various tissues of rats. 50 and 100 ppm of PGRs as drinking water were administered orally to rats (Sprague-Dawley albino) ad libitum for 25 days continuously. The PGRs treatment caused different effects on the serum marker enzymes, antioxidant defense systems, and the MDA content in experimented rats compared to controls. Results showed that TIBA caused a significant decrease in serum AST activity with both the dosage whereas serum CPK was significantly increased with 100 ppm dosage of TIBA. Meanwhile, serum AST, CPK, and LDH activities were significantly increased with both dosage of NAA and 2,4-D. The lipid peroxidation end-product MDA significantly increased in the all tissues treated with both dosages of PGRs without any change in the brain and erythrocyte of rats treated with both the dosages of 2,4-D. The GSH depletion in the kidney and brain tissues of rats treated with both dosages of PGRs was found to be significant. Furthermore, the GSH depletion in the erythrocyte of rats treated with both dosages of PGRs except 50 ppm dosage of 2,4-D was significant too. Also, the GSH level in the liver was significantly depleted with 50 ppm of 2,4-D and NAA, whereas the GSH depletion in the same tissue did not significantly change with the treatment. The activity of antioxidant enzymes was also seriously affected by PGRs; SOD significantly decreased in the liver, heart, kidney, and brain of rats treated with both dosages of NAA, whereas the SOD activity in the erythrocytes, liver, and heart was either significantly decreased or not changed with two doses of 2,4-D and TIBA. Although the CAT activity significantly increased in the erythrocyte and brain of rats treated with both doses of PGRs, it was not changed in the liver, heart, and kidney. Meanwhile, the ancillary enzyme GR activity significantly increased in the brain, heart, and liver but decreased in the erythrocyte and kidney of rats treated with both doses of PGRs. The drug-metabolizing enzyme GST activity significantly increased in the heart and kidney but decreased in the brain and erythrocytes of rats treated with both dosages of PGRs. As a conclusion, the results indicate that PGRs might affect antioxidant potential enzymes, the activity of hepatic damage enzymes, and lipid peroxidation dose independently. Also, the rats resisted to oxidative stress via antioxidant mechanism but the antioxidant mechanism could not prevent the increases in lipid peroxidation in rat's tissues. These data, along with the determined changes, suggest that PGRs produced substantial systemic organ toxicity in the erythrocyte, liver, brain, heart, and kidney during the period of a 25-day subacute exposure.     

Effect of age and dietary protein level on tissue mineral levels in female rats

Mineral (phosphorus, sulfur, potassium, calcium, magnesium, iron, zinc, copper, and manganese) concentrations were measured in plasma, and several tissues from female Wistar rats (young: 3-wk-old; mature: 6-mo-old) were fed on a dietary regimen designed to study the combined or singular effects of age and dietary protein on mineral status. Three diets, respectively, contained 5, 15, and 20% of bovine milk casein. Nephrocalcinosis chemically diagnosed by increased calcium and phosphorus in kidney was prevented in rats fed a 5% protein diet. Renal calcium and phosphorus were more accumulated in young rats than mature rats. A 5% protein diet decreased hemoglobin and blood iron. The hepatic and splenic iron was increased by a 5% protein diet in mature rats but was not altered in young rats. Mature rats had higher iron in brain, lung, heart, liver, spleen, kidney, muscle, and tibia than young rats. A 5% protein diet decreased zinc in plasma and liver. Zinc in tibia was increased with dietary protein level in young rats but was not changed in mature rats. A 5% protein diet decreased copper concentration in plasma of young rats but not in mature rats. Mature rats had higher copper in plasma, blood, brain, lung, heart, liver, spleen, and kidney than young rats. With age, manganese concentration was increased in brain but decreased in lung, heart, liver, kidney, and muscle. These results suggest that the response to dietary protein regarding mineral status varies with age.     

Effects of angiotensin II type 1 receptor blockade on the oxidative stress in spontaneously hypertensive rat tissues

The aim of this work was to investigate the production of oxidative damage in homogenized kidney, liver and brain of spontaneously hypertensive rats (SHR), as well as the involvement of angiotensin (Ang) II in this process. Groups of 12-week-old SHR and Wistar Kyoto rats (WKY) were given 10 mg/kg/day losartan in the drinking water during 14 days. Other groups of WKY and SHR without treatment were used as controls. The production of thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (Gpx) were determined. No significant difference in TBARS was observed between untreated SHR or WKY rats; GSH content was lower in the liver but higher in the brain of SHR compared to WKY rats. In tissues from the SHR group, SOD and Gpx activities were reduced, whereas CAT activity was slightly increased in kidney. TBARS levels did not change in WKY rats after losartan administration, but were reduced in SHR liver and brain. Losartan treatment decreased GSH content in WKY kidney, but increased GSH in SHR liver. The activity of the antioxidant enzymes was not modified by losartan in WKY rats; however, their activities increased in tissues from treated SHR. The lower activity of antioxidant enzymes in tissues from hypertensive rats compared to those detected in normotensive controls, indicates oxidative stress production. Ang II seems to play no role in this process in normotensive animals, although AT1 receptor blockade in SHR enhances the enzymatic activity indicating that Ang II is implicated in oxidative stress generation in the hypertensive animals.     

Presence of D-aspartate oxidase and free D-aspartate in amphibian (Xenopus laevis, Cynops pyrrhogaster) tissues.

1. This paper is the first report on the presence of D-aspartate oxidase activity and free D-aspartate in the amphibian tissues. 2. The presence of D-aspartate oxidase activity in tissues of clawed toad (Xenopus laevis) and Japanese newt (Cynops pyrrhogaster) was demonstrated by requirements for enzyme activity, selective inhibition with meso-tartrate and substrate specificity. 3. In each animal, the highest activity was found in kidney, followed by liver and brain, and no gender difference in the specific activity was observed in each tissue. 4. A small but significant amount of D-aspartate was detected in liver and kidney, irrespective of species. 5. In the newt, there was a gender difference in the hepatic and renal content of D-aspartate and not in the D-/D+L-aspartate ratio.     

Placental transfer of halogenated benzenes (pentachloro-, pentachloronitro-, and hexabromo-) in rats.

The present study was carried out to provide information on the placental transfer of three organohalogens of environmental concern. Pentachloro-, pentachloronitro-, and hexabromobenzene were administered per os to rats daily on days 6 through 15 of gestation at level of 40, 100, and 200 mg/kg body weight. On day 22, the dams were killed and fetuses removed by caesarean section. Maternal brain, heart, kidney, liver, spleen and adipose tissue as well as whole fetus, fetal liver and fetal brain were analyzed for organohalogen residue by GLC. Pentachlorobenzene accumulated in the fetus to a greater extent than hexabromobenzene. In maternal tissues pentachlorobenzene accumulated to the greatest extent in adipose tissue, followed by liver, spleen, brain, heart and kidney. With hexabromobenzene, the greatest accumulation was observed in adipose tissue, followed by spleen, liver, heart, kidney and brain. Pentachloronitrobenzene was not detected (0.05 p.p.m.) in any maternal or fetal tissue.     

Alterations of Antioxidant Enzymes and Oxidative Damage to Macromolecules in Different Organs of Rats During Aging

Oxygen free radicals have been hypothesized to play an important role in the aging process. To investigate the correlation between the oxidative stress and aging, we have determined the levels of oxidative protein damage and lipid peroxidation in the brain and liver, and activities of antioxidant enzymes in the brain, liver, heart, kidney, and serum from the Fisher 344 rats at ages of 1, 6, 12, 18, and 24 months. The results showed that the level of oxidative protein damage (measured as carbonyl content) in the brain and liver was significantly higher in older animals than in young animals. No statistical difference was observed in the lipid peroxidation of the liver and brain between young and old animals. The activities of antioxidant enzymes in most tissues displayed an age-dependent decline. Superoxide dismutases in the heart, kidney, and serum, glutathione peroxidase activities in the serum and kidney, and catalase activities in the brain, liver, and kidney, significantly decreased during aging. Cytochrome c oxidase, an enzyme involved in electron transport in mitochondria, initially increased, but subsequently decreased in the aged brain, whereas no significant alteration was observed in the liver mitochondrial antioxidant enzymes. The present studies suggest that the accumulation of oxidized proteins during aging is most likely to be linked with an age-related decline of antioxidant enzyme activities, whereas lipid peroxidation is less sensitive to predict the aging process.     

The influence of chromium chloride consumption on lipid peroxidation and activity of the antioxidant defense in rat tissues

The effect of food supplementation with chromium (CrCl₃ · 6H₂O) on intensity of peroxide processes and activity of antioxidant enzymes has been investigated in some rat tissues. Food supplementation with 200 μg/kg CrCl₃ · 6H₂O for 30 days resulted in the increase of tissue chromium. The tissue chromium content of chromium-treated rats decreased in the following order: spleen, heart, kidney, lung, brain, liver, skeletal muscles. All organs and tissues (except skeletal muscles) of chromium-treated rats were characterized by decreased content of lipid peroxidation (LPO) products: hydroperoxides and thiobarbituric acid reactive substances (TBARS). The maximal reduction in LPO products was observed in spleen, kidney, liver, and lung. Treatment with chromium also caused an increase in the activity of glutathione peroxidase, glutathione reductase, and calatase in all tissues and organs studied. In the brain and kidney an increase in the content of reduced glutathione was observed. Superoxide dismutase activity was higher in myocardium and skeletal muscles, basically equal in lung and liver, while in other organs (brain, kidney, spleen) of experimental animals it was lower than in control animals. Results of this study suggest that chromium exhibits tissue/organ-specific regulatory effects on enzymes of the antioxidant defense     

Effects of subacute treatment of ethylene glycol on serum marker enzymes and erythrocyte and tissue antioxidant defense systems and lipid peroxidation in rats

The present study was aimed to investigate the effects of ethylene glycol (EG) on serum marker enzymes, antioxidant defense systems and lipid peroxidation concentration (malondialdehyde=MDA) in various tissues of rats exposed to ethylene glycol. EG (1.25% or 2.5%) in drinking water was administered orally to rats (Sprague-Dawley albino) ad libitum for 21 days continuously. EG treatments caused different effects on the serum marker enzymes, antioxidant defense system and MDA content in various tissues of the treatment groups as compared with the controls. EG also caused a significant increase in the serum marker enzyme activities with 2.5% dosage whereas, no changes were not observed with 1.25% dosage of EG treatment. Lipid peroxidation significantly increased in all the tissues except for in the heart and stomach of rats treated with both dosages of EG. Also, the antioxidative systems were also seriously affected by EG. For example, SOD significantly decreased in the liver treated with both dosages whereas, SOD activity in the erythrocytes, kidney, heart and stomach were significantly increased and not changed in the brain with two dosages of EG. Also, while CAT activity significantly decreased in the erythrocytes, liver and kidney, the activity in the stomach significantly increased, but did not change in the brain and heart with two doses of EG. GR activity significantly decreased in the erythrocytes treated with both dosages of EG whereas GR was not affected in other tissues by EG treatment. GST activity significantly elevated in the heart and brain but did not change in the other tissues of rats treated with both dosages of EG. Meanwhile, GSH depletion in the erythrocytes of rats treated with 2.5% dosage of EG was found to be significant whereas, the level of GSH in the brain was significantly increased treated with both the dosages of EG. The observations presented led us to conclude that the administration of subacute EG promotes lipid peroxidatin content, elevates tissue damage serum marker enzymes and changes in the antioxidative systems in rats. These data, along with the determined changes suggest that EG produced substantial systemic organ toxicity in the erythrocyte, liver, brain, heart kidney and stomach during the period of a 21-day subacute exposure.     

Effects of diet and of alloxan-diabetes on the activity of branched-chain 2-oxo acid dehydrogenase complex and of activator protein in rat tissues.

The total activities (sum of active and inactive forms) of branched-chain 2-oxo acid dehydrogenase complex in tissues of normal rats fed on a standard diet were (unit/g wet wt.): liver, 0.82; kidney, 0.77; heart, 0.57; hindlimb skeletal muscles, 0.034. Total activity was decreased in liver by 9%- or 0%-casein diets and by 48 h starvation, but not by alloxan-diabetes. Total activities were unchanged in kidney and heart. The amount of active form of the complex (in unit/g wet wt. and as % of total) in tissues of normal rats fed on standard diet was: liver, 0.45, 55%; kidney, 0.55, 71%; heart, 0.03, 5%; skeletal muscle less than 0.007, less than 20% (below lower limit of assay). The concentration of the active form of the complex was decreased in liver and kidney, but not in heart, by low-protein diets, 48 h starvation and alloxan-diabetes. In heart muscle alloxan-diabetes increased the concentration of active complex. The concentration of activator protein (which activates phosphorylated complex without dephosphorylation) in liver and kidney was decreased by 70-90% by low-protein diets and 48 h starvation. Alloxan-diabetes decreased activator protein in liver, but not in kidney. Evidence is given that in tissues of rats fed on a normal diet approx. 70% of whole-body active branched chain complex is in the liver and that the major change in activity occasioned by low-protein diets is also in the liver.     

Pyridoxamine (pyridoxine) phosphate oxidase activity in mammalian tissues

1. Vitamin B6-sufficient rats had moderate pyridoxamine-P oxidase specific activities in heart, brain, kidney and liver, but no detectable activity in skeletal muscle. Vitamin B6-deficiency in rats resulted in a decreased oxidase activity in liver but no change in the activities in other tissues. 2. The pyridoxamine-P oxidase activity in vitamin B6-sufficient mice was high in liver, moderate in brain and kidney, and not measurable in skeletal muscle and heart. Vitamin B6-deficient, compared with control mice, had decreased oxidase activities in brain, kidney and liver. 3. Mouse erythrocytes took up pyridoxine more rapidly than did rat and human erythrocytes. 4. Mouse and human erythrocytes rapidly converted pyridoxine to pyridoxal-P. Rat, hamster and rabbit erythrocytes had appreciably lower pyridoxamine-P oxidase activity than did mouse and human erythrocytes.     

Changes in kynurenine pathway metabolism in the brain, liver and kidney of aged female Wistar rats

The kynurenine pathway of tryptophan catabolism plays an important role in several biological systems affected by aging. We quantified tryptophan and its metabolites kynurenine (KYN), kynurenine acid (KYNA), picolinic acid (PIC) and quinolinic acid (QUIN), and activity of the kynurenine pathway enzymes indoleamine 2,3-dioxygenase (IDO), tryptophan 2,3-dioxygenase (TDO) and quinolinic acid phosphoribosyltransferase (QPRTase), in the brain, liver and kidney of young, middle-aged and old female Wistar rats. Tryptophan levels and TDO activity decreased in all tissues with age. In contrast, brain IDO activity increased with age, while liver and kidney IDO activity decreased with age. The levels of KYN, KYNA, QUIN and PIC in brain all increased with age, while the levels of KYN in the liver and kidney showed a tendency to decrease. The levels of KYNA in the liver did not change, but the levels of KYNA in the kidney increased. The levels of PIC and QUIN increased significantly in the liver but showed a tendency to decrease in the kidney. QPRTase activity in both brain and liver decreased with age but was elevated in the kidney in middle-aged (12-month-old) rats. These age-associated changes in tryptophan metabolism have the potential to impact upon major biological processes, including lymphocyte function, pyridine (NAD(P)(H)) synthesis and N-methyl-d-aspartate (NMDA)-mediated synaptic transmission, and may therefore contribute to several degenerative changes of the elderly.     

Carnitine palmitoyltransferase in liver and five extrahepatic tissues in the rat. Inhibition by DL-2-bromopalmitoyl-CoA and effect of hypothyroidism.

Mitochondria were isolated from rat adult liver, foetal liver, kidney cortex, heart, skeletal muscle and interscapular brown adipose tissue. DL-2-Bromopalmitoyl-CoA inhibited the overt form of carnitine palmitoyltransferase (CPT1) in heart, skeletal muscle and brown adipose tissue, with an IC50 value (concentration giving 50% inhibition) of 1.3-1.6 microM. By contrast, the IC50 value for inhibition of the kidney or adult liver enzyme was 0.08-0.1 microM. CPT1 in near-term foetal liver differed from that in adult liver in that the IC50 for inhibition by 2-bromopalmitoyl-CoA was 0.57 microM. It is suggested that there may be tissue-specific forms of the catalytic entity of CPT1 and that foetal liver may contain a mixture of adult liver- and muscle-type enzymes. In rats made hypothyroid by administration of propylthiouracil and an iodine-deficient diet, hepatic CPT1 activity was decreased by 83%. However, CPT1 activity in extrahepatic tissues showed no adaptive decrease in hypothyroidism.     

Effects of ischaemia on content of metabolites in rat liver and kidney in vivo

1. The time-course of changes in content of intermediates of glycolysis in rat liver and kidney cortex after severance of blood supply was investigated. 2. The decline in content of ATP was more rapid in kidney (1.7-0.5mumol/g in 30s) than in liver (2.7-1.6mumol/g in 60s). In both tissues AMP and P(i) accumulated. 3. Net formation of lactate was 1.7mumol/g during the second minute of ischaemia in liver from well-fed rats, 1.1mumol/g in liver from 48h-starved rats, and about 1.0mumol/g during the first 30s of ischaemia in kidney. Net formation of alpha-glycerophosphate was rapid, especially in liver. 4. In kidney the concentration of beta-hydroxybutyrate rose, but that of alpha-oxoglutarate and acetoacetate decreased. 5. In both organs the concentrations of fructose diphosphate and triose phosphates increased during ischaemia and those of other phosphorylated C(3) intermediates decreased. 6. The concentration of the hexose 6-phosphates rose rapidly during the first minute of ischaemia in liver, but decreased during renal ischaemia. 7. In kidney the content of glutamine fell after 2min of ischaemia, and that of ammonia and glutamate rose. 8. The redox states of the cytoplasmic and mitochondrial NAD couple in kidney cortex were similar to those in liver. 9. The regulatory role of glycogen phosphorylase, pyruvate kinase and phosphofructokinase is discussed in relation to the observed changes in the concentrations of the glycolytic intermediates.     

Influence of age on lead-induced oxidative stress in rat

Influence of age on lead-induced oxidative stress was investigated in young, adult, and old rats maintained on 0.2% lead acetate (2000 ppm lead) in drinking water for 3 mo. The lead-induced depletion of blood and liver reduced glutathione was about equal in young and adult but not in old rats. The increases in blood, liver, and brain oxidized glutathione and blood and liver superoxide dismutase levels were related to the accumulation of lead in these tissues and followed the order young >adult>old. The lead-induced inhibition of blood δ-aminolevulinic acid dehydratase activity, lowering in hemoglobin, and enhanced urinary excretion of δ-aminolevulinic acid were independent of variation in age. The results indicate that young rats may be most sensitive, whereas old rats may be most resistant to some of the oxidative effects of lead examined, which may be related to the accumulation of lead.     

Differential effect of sunflower seed oil on hepatic and renal D-amino acid oxidase in the rat.

1. The specific activity of hepatic and renal peroxisomal D-amino acid oxidase (D-AAOX) was measured in rats fed diets containing various quantities of vegetable oil. 2. Increasing the amount of dietary sunflower seed oil (SSO) from 10 to 25% (w/w) reduced the specific activity of hepatic D-AAOX by up to 30% after 10 days. 3. In both tissues, the enzyme activity was moderately decreased during the first two-day period after administration of the 25% SSO diet was begun. Unlike hepatic D-AAOX, renal D-AAOX returned to its baseline level in the kidney after the third day. 4. In contrast to SSO, hydrogenated coconut oil (HCO) did not evoke alterations of D-AAOX activity. 5. The activity levels of another peroxisomal enzyme, L-2-hydroxy acid oxidase (L-HAOX), in the liver of rats fed the high-SSO diet vs those fed the control diet were similar. 6. The subcellular distribution of D-AAOX and L-HAOX was not altered in the liver of rats fed the 25% SSO diet during the 10-day period.