Tiobarbituric Acid Reactive Substances Research Articles

Intake of oligoelements with cytarabine or etoposide alters dopamine levels and oxidative damage in rat brain

Research on the relationships between oligoelements (OE) and the development of cancer or its prevention is a field that is gaining increasing relevance. The aim was to evaluate OE and their interactions with oncology treatments (cytarabine or etoposide) to determine the effects of this combination on biogenic amines and oxidative stress biomarkers in the brain regions of young Wistar rats. Dopamine (DA), 5-Hydroxyindoleacetic acid (5-Hiaa), Glutathione (Gsh), Tiobarbituric acid reactive substances (TBARS) and Ca+2, Mg+2 ATPase enzyme activity were measured in brain regions tissues using spectrophometric and fluorometric methods previously validated. The combination of oligoelements and cytarabine increased dopamine in the striatum but decreased it in cerebellum/medulla-oblongata, whereas the combination of oligoelements and etoposide reduced lipid peroxidation. These results suggest that supplementation with oligoelements modifies the effects of cytarabine and etoposide by redox pathways, and may become promising therapeutic targets in patients with cancer.

Inhibition of Protein and Lipid Oxidation in Ready-to-Eat Chicken Patties by a Spondias mombin L. Bagasse Phenolic-Rich Extract.

This study evaluated the impact of yellow mombin (Spondias mombin L.) bagasse extract (YMBE) on the color degradation, protein and lipid oxidation in ready-to-eat chicken patties during 15 days of refrigerated storage. Two formulations of chicken patties were developed: chicken patties control - PCON (without the antioxidant extract) and chicken patties with yellow mombin extract - PYME (with the antioxidant extract). The extract was effective in maintaining red color and inhibiting myoglobin degradation in the evaluated samples. The generation of lipid oxidation compounds during storage of the treated samples was delayed by 92.37% for peroxide index, 89.89% for conjugated dienes, 74.29% for tiobarbituric acid reactive substances (TBARs) and 92.55% for ρ-anisidine compared to the control samples. Moreover, the addition of YMBE inhibited the formation of carbonyl compounds during cold storage compared to the control samples. Extracts obtained from the yellow mombin bagasse act as a good natural antioxidant for ready-to-eat chicken patties inhibiting protein and lipid oxidative damage during cold storage, being a potential preservative to replace synthetic antioxidants in meat products.

Aktivitas Ekstrak Daun Binahong(Anredera cordifolia (Ten.) Steenis) sebagai Antihiperurisemia dan Antioksidan pada Tikus Hiperurisemia

ABSTRACT : The Binahong plant ( Anredera cordifolia (Ten.) Steenis) has been used to treat several types of diseases. To find another possible biological activities, we investigated binahong leaves antihyperuricemic and antioxidant activity through in vitro assay of xanthine oxidase inhibiting activity of binahong ethanol extract and through in vivo assay by measuring uric acid and malondialdehyde (MDA) levels in plasma of hyperuricemic rat treated with binahong ethanol extract. Rat was induced into hyperuricemiccondition using chicken concentrate which is administered orally for 7 days and potassium oxonic through intraperitoneal routeon the last day. In treatment groups, rat were administered with extract at doses 200, 400 and 800 mg/kg BW respectively along the induction periods, while theother group were given allopurinol. On 7 th day, the levels of plasma uric acid andMDA were measured by enzymatic methods and tiobarbituric acid reactive substances (TBARS) methodconsecutively. In vitro study shows that at 100 ppm,binahong leavesethanolic extract inhibit xanthine oxidase activity by24.33%, while in vivo study showedthe extract hadantihyperuricemic activity by decreasinguric acid levels at dose 800 mg / kgBB about 60,88% compared to hyperuricemia control group. Plasma MDA levels showed that hyperuricemia induction for 7 days was not enough to show significant increase of MDA levels.As conclusion, the ethanolic extract of binahong leaves could lower uric acid levels but in this study it’s activity as antioxidant could not be proven through MDA measurements.

Rapamycin and fructose-1,6-bisphosphate reduce the HEPG2 cell proliferation via increase of free radicals and apoptosis.

Hepatocellular carcinoma is the most prevalent type of tumor among primary tumors affecting the liver. Rapamycin is currently used as a basis for chemotherapy in the treatment of cancers, including the liver. Because it shows several adverse effects, minimizing these effects without compromising efficacy is important. In this sense other drugs may be used concomitantly. One of these drugs is fructose-1,6-bisphosphate (FBP), which has shown therapeutic effect in various pathological situations, having antioxidant and anti-inflammatory proprieties. The objective of the present study was to evaluate the activity of rapamycin in combination with the FBP in HepG2 cell proliferation and the mechanisms involved. HepG2 cells were analyzed after 72h of treatment with both drugs. Cell proliferation, cytotoxicity, cytokines, apoptosis, senescence, autophagy and oxidative stress were accessed. Ιt was demonstrated that the combination is more efficient than the single use of substances, because subtherapeutic doses of rapamycin, when associated to FBP become effective, reducing cell proliferation, through a significant increase in the production of tiobarbituric acid reactive substances (TBARS), suggesting that this might be the cause of death by apoptosis. According to these results, we believe that the association of both drugs may be a promising choice for the treatment of hepatocarcinoma.

Paraquat inhibits progesterone synthesis in human placental mitochondria

IntroductionHuman placenta mitochondria produces huge amounts of progesterone necessary for maintaining the pregnancy. Lipid peroxidation in human placental mitochondria inhibits progesterone synthesis and that inhibition can be reversed by superoxide dismutase and other antioxidants. Paraquat (PQ) a highly toxic herbicide generates superoxide radical inside cells and induces lipid peroxidation. Hence, it is supposed to stimulate lipid peroxidation in human placental mitochondria and in consequence to inhibit a placental mitochondrial steroidogenesis. MethodsPlacentas were obtained from normal pregnancies. All experiments were done using isolated human placental mitochondria. Mitochondrial lipid peroxidation was determined as tiobarbituric acid reactive substances (TBARS). A conversion of cholesterol to pregnenolone or pregnenolone to progesterone was measured using radiolabeled steroids and thin layer chromatography. ResultsPQ enhanced the iron-dependent lipid peroxidation as also PQ heightened the inhibitory action of this process on progesterone synthesis in isolated human placental mitochondria. Paradoxically, a superoxide dismutase (SOD) reversed the inhibition of progesterone synthesis only minimally although it strongly inhibited PQ stimulated iron-dependent lipid peroxidation. When iron was absent, PQ stimulated only negligible lipid peroxidation but strongly inhibited progesterone synthesis. SOD had no effect on inhibition of progesterone synthesis by PQ. PQ strongly inhibited of the conversion of cholesterol to pregnenolone but had not got any influence on the enzymatic activity of mitochondrial 3β-hydroxysteroid dehydrogenase. PQ strongly decreased the efficiency of NADPH-dependent cytochrome P450 reduction as well as it promoted the rapid oxidation of the pre-reduced mitochondrial cytochrome P450. However PQ has not inhibited combined activity of adrenodoxin reductase and adrenodoxin. DiscussionWe conclude that the most important reason of the inhibition of progesterone synthesis by PQ is the escape of electrons from cytochrome P450scc to that compound what leads to cytochrome oxidation and, in consequence the inhibition of the reaction catalyzed by it. The action of PQ described here should be considered as potentially harmful for pregnancy and fetal development.

Effect of biologically active substances present in water extracts of white mustard and coriander on antioxidant status and lipid peroxidation of mouse C2C12 skeletal muscle cells.

Coriander and white mustard, an annual plants originated in the Mediterranean region, have been cultivated and used as spices for a long time. Recent studies have shown that they may constitute a potential source of phenolic compounds. The aim of this study was to evaluate the content of polyphenols in coriander and white mustard water extracts and to investigate their antioxidant activity in C2C12 mouse skeletal muscle cells, which serve as a good model of cells with intensive metabolism. HPLC analysis showed that polyphenols were able to permeate from the water extracts of studied plants into the undifferentiated myoblasts as well as myocytes undergoing differentiation, increasing the concentration of reduced glutathione and upregulating glutathione reductase and peroxidase activity. White mustard and coriander extracts also decreased the levels of oxysterols and sum of tiobarbituric acid reactive substances (TBARS) in both: myoblasts and differentiating myocytes, demonstrating protective effect on cell membranes. The obtained results indicate that polyphenols synthesized by both herbs may have beneficial effects on muscle tissue.

Effect of Myrtle (Myrtus communis) Extracts on Storage Stability of Chicken Frankfurters

The antioxidant and antimicrobial effects of water myrtle extracts (0.25 and 0.50%) were investigated against lipid oxidation (tiobarbituric acid reactive substances – TBARS) and microbial growth in vacuum-packed chicken frankfurters stored at 4±1ÂoC for 35 days. The effects of this extract on compositional, physicho-chemical and sensory characteristics of chicken frankfurters were also determined. Results showed that water myrtle extracts possess antioxidant (lower TBARS values that remained stable during the 35 days of storage) and antimicrobial properties (lower aerobic plate count) that may make them useful in the food industry. The addition of water myrtle extracts to frankfurters increased red/green and yellow/blue coordinates and decreased lightness values, which could indicate that Myrtus comunnis extract can also acts as a colorant in this type of meat products. Frankfurters with water myrtle extracts were scored similar to controls for overall appearance.

Hepatoprotective and antioxidant activity of anthocyanins in black rice bran on carbon tetrachloride-induced liver injury in mice

The benefits of anthocyanin-rich black rice bran extract (ARBE) on the liver of carbon tetrachloride (CCl4)-intoxicated mice was investigated. Based on the in vivo experiment, the effect of cyanidin-3-glucoside (Cy-3-G) and peonidin-3-glucoside (Pn-3-G), the predominant anthocyanins in ARBE, on CCl4 insulted hepatocytes L-02 was further evaluated. Mice treated with ARBE for 7weeks by oral administration showed reduced aminotransferase activities in serum, accompanied by enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, while tiobarbituric acid reactive substances (TBARS), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels were significantly decreased compared to CCl4-intoxicated model group. Histopathological observation showed ARBE administration alleviated the pathological changes in livers of CCl4-intoxicated mice. Similarly, preincubation of L-02 cells with Cy-3-G or Pn-3-G significantly alleviated CCl4-induced injury dose-dependently, exhibited higher cell viability, decreased aminotransferase activity and enhanced cellular antioxidant status. Furthermore, Cy-3-G showed much stronger hepatoprotective activity than Pn-3-G at the same concentration. HPLC analysis showed that Cy-3-G accounted for more than 88% of total anthocyanins in ARBE. These results indicate that ARBE is significantly beneficial to liver health, and that Cy-3-G is the predominant anthocyanin in ARBE exerting this effect. The antioxidant activity of anthocyanins is an important mechanism by which ARBE exerts hepatic health benefit.

Efeito da adição de glutationa na função e estresse oxidativo em sêmen ovino criopreservado

The high susceptibility of sperm to the oxidative stress occurs especially due to high content of poly-unsaturated fattyacids (PUFAs) in its plasma membrane. The PUFAs provide the necessary fluidity to the plasma membrane. Howeverdouble bonds present in those fatty acids are more susceptible to oxidative stress. Studies in human indicate thatcryopreservation may lead to damages to the sperm due to oxidative stress. This study aimed to verify if the antioxidantglutathione (GSH) may protect ovine cryopreserved sperm against damages caused by oxidative stress. Semen samplesof four rams were cryopreserved using Tris-egg yolk extender supplemented with different concentrations of reducedglutathione (control, 1, 5 and 10 mM). After thawing, samples were evaluated using conventional (motility and vigor)and functional tests (membrane integrity and mitochondrial activity). Aliquots of each thawed sample were submitted toprotocol of induced lipid peroxidation using ascorbate (20 mM) and ferrous sulphate (4 mM), with further measurementof tiobarbituric acid reactive substances (TBARS), index of oxidative stress. No effect of GSH was observed on variablesassessed by conventional tests. GSH decreased the proportion of intact acrosomes. Samples treated with 5 mM GSHshowed lower percentage of intact membrane cells when compared to control samples and those treated with 10 mM.The percentage of cells with mitochondrial activity was affected by GSH, but no effect on TBARS. Samples from controlgroup were more susceptible to denaturation of chromatin. In conclusion, the addition of Glutathione (GSH) offersprotection to DNA and mitochondrial activity of ovine sperm.

Effect of long term administration of resveratrol on lipid concentration in selected organs and liver’s histology in rats fed high fructose diet

The aim of this study was to evaluate the effect of long term administration (4months) of resveratrol (RSV) with high fructose (HF) diet (63%) on selected biochemical parameters and lipids content in different tissues of rats. Lipid profile in serum of rats was not affected by the addition of resveratrol to the experimental diets. The concentration of tiobarbituric acid reactive substances (TBARS; expressed as the melanodialdehyde – MDA equivalents) was significantly lower in the serum of rats fed HF diet with the addition of 0.04% and 0.06% of resveratrol. Crude lipids content in hearts was lower in rats fed with HF diet with the addition of 0.06% RSV. The concentration of lipids was also significantly lower in the liver of animals fed with HF diet with the addition of 0.04% or 0.06%. These results indicated that resveratrol significantly decreased fat accumulation and oxidative stress in rats fed with a high fructose diet.

PEUCEDANUM OREOSELINUM L. MOENCH EFFECT IN EHRLICH ASCITIC CARCINOMA

Peucedanum oreoselinum L. Moench; ( fam. Apiaceae ); belongs to a large group of medicinal plants; spread around the world; used for wide range therap eutic purposes. The aerial part ( Herba ) was collected; from a couple of areas of Transylvania; the compounds were initially identified by chromatography; and then m easured by High Performance Liquid Chromatography (HPLC). Latter a tincture 1:5 in ethylic alcohol 50°was made . After the toxicity tests; the experiment was carrie d out for 10 days; on 20 white Swiss male mice; eac h animal received; intraperitoneally 10 6 cells from Ehrlich ascitic carcinoma; in the first day. Experimental group received daily 0.1 ml P. oreoselinum 1:5 in ethylic alcohol 50° while control group 0.1 ml alcohol 50°. Total amount of ascitic fluid was measured; and viable tumour cell concentration was counted; production of tiobarbitu ric acid reactive substances (TBARS) was used to evaluate the plasma lipid peroxides levels. HPLC analysis reve aled a significant content of phenols; flavonoids and coum arins; strongly related to the place of harvesting. Acute toxicity tests revealed no signs of toxicity. Ascit ic Ehrlich carcinoma model provided no significant antiproliferative activity (even the ascitic volume and tumour cell concentration is lower in treated animals as compared to control; it was not statically covered) ; but P. oreoselinum therapy had an important antioxidant effect (p<0.05); treated animals shown lower TBARS levels (2.4±33 nmol/l) as compared to control group (6.1±1.54 nmol/l). Therefore; P. oreoselinum might be a useful tool in palliative cancer therap y.

Effects of Copaifera langsdorffii Desf. on Ischemia-Reperfusion of Randomized Skin Flaps in Rats

Copaíba oil is an oleoresin obtained from the Copaiffera langsdorffii genus (Leguminoseae). It is widely used in folk medicine as an antiinflammatory, healing, and antiseptic agent. Comparative pharmacologic studies between different species of copaíba oils are scarce. The protective effect of Copaiffera langsdorffii was evaluated on an experimental model of random skin flaps on rat dorsums. Seventy-two Wistar rats (average weight = 216.8 g) were divided randomly into four equal groups (saline control, vehicle control, GT200-Test 1, and GT400-Test 2). A caudally based rectangular flap, 2.5-8.0 cm in size, was elevated on the back of the rat using McFarlane's method. The flap was sutured back into its original place. Copaifera and control drugs (saline and Tween 80) were administered by gavage 24, 12, and 2 h prior to the beginning of the experiment followed by daily doses for the next 7 days. To observe the effects of Copaifera, laboratory analyses included plasma and tissue levels of tiobarbituric acid-reactive substances (TBARS) and reduced glutathione (GSH) and tissue levels of myeloperoxidase (MPO). The oil-resin of copaíba presents discrete antilipoperoxidation action, intense antioxidant action, and antiinflammatory activity during the ischemia and reperfusion of randomized cutaneous flaps. The effects of ischemia-reperfusion are complex and substances capable of increasing the tolerance of tissue to those effects by reducing the production or neutralizing the action of free radicals are needed.

Influence of oral glutamine and glucose on markers of oxidative stress in a paraquat rat model

Summary Background & aims l -glutamine ( l-G ln ) is involved in several metabolic processes, and is classified as an essential amino acid in demanding metabolic conditions. The amino acids G ln, cysteine and glycine are the precursors of the tripeptide glutathione synthesis, which is present in cells mainly in the reduced form, one of the most important endogeneous antioxidant defense front. Considering that G ln, as glucose (Gluc), can be used as oxidative fuel molecules by the cells, the aim of this work was to investigate the G ln and Gluc influence on reduced glutathione content and oxidative damage, induced by paraquat. Methods Glutathione content and oxidative damage were monitored by the formation of thiolate anions and tiobarbituric acid reactive substances, respectively. Paraquat, G ln and Gluc were given in 30 mg/kg body weight (BW), 1.0 M and 4.0 g/kg BW, respectively. Results G ln was effective by increasing (∼40%) plasma glutathione levels under oxidative stress and decreasing (∼16%) TBARS levels in the hepatic tissue, while Gluc had a non-significant effect. On the other hand, in renal tissue upon oxidative stress TBARS levels were increased by G ln (∼55%) and Gluc (∼47%) inducing tissue damage. Conclusions In this work, we have shown in vivo, i.e. in the presence of all metabolic interactions, an organ-specific effect of substrate administration, the G ln optimized plasma glutathione, protecting the hepatic tissue against oxidative damages. The same effect was not observed for renal tissue.

The effect of sex and dietary antioxidants β-carotene, vitamins C and E in a CLA-enriched diet on the lipid profile and oxidative stability of pork meat

Fifty Polish Large White growing pigs were randomly divided into 5 groups (5 gilts and 5 barrows in each group) and fattened from 50 to 105 kg body weight. The experimental factors were gender and addition of vitamins C, E and β-carotene to the diets. All diets were supplemented with 0.5% CLA. Polyunsaturated fatty acids (PUFA) were observed to decrease in pigs receiving combined vitamins C, E and β-carotene compared with pigs receiving a single supplement of β-carotene (P<0.05). In gilts the level of saturated fatty acids (SFA) was significantly lower and the content of unsaturated fatty acids (UFA) and PUFA was significantly higher than in barrows (P<0.01) . A high significant difference (P<0.01) was also found between gilts and barrows in the PUFA/SFA ratio. The CLA concentration was significantly higher in gilts than in barrows (P<0.05). Highly significant sexdependent differences were found in the content of crude fat, which was significantly lower (P<0.01) in gilts than in barrows. The pH of meat 24 h postmortem was 5.44 in gilts and 5.55 in barrows (P<0.01). Yellowness (b*) was found to decrease in all experimental groups compared with the control group (P<0.01). There was a tendency towards a lower concentration of tiobarbituric acid reactive substances (TBARS) after 3-month storage of frozen meat in the group receiving supplemental vitamin E and combined vitamins C, E and β-carotene compared with the group receiving β-carotene alone (P<0.05). The vitamin supplements caused significant changes in the vitamin E content of meat

15 EFFECT OF BULL EPIDIDYMIS STORAGE CONDITIONS ON CRYOPRESERVED EPIDIDYMAL SPERM IN VITRO FERTILITY AND LIPID PEROXIDATION STATUS

Although cryopreservation of epididymal sperm has been studied extensively in several species, some factors that could negatively influence its quality are still unknown, such as the storage conditions of the epididymides prior to sperm collection. Studies indicate that the lower the storage temperature, the better the sperm quality after collection (Kaabi et al. 2003 Theriogenology 60, 1249–1259). An additional factor is lipid peroxidation in which sperm membrane resistance against reactive oxygen species (ROS) attacks is an important component. The objective of this experiment was to study whether the epididymis storage temperature following slaughter, as well as the intrinsic resistance against oxidative stress, affects the fertilizing capacity of cryopreserved epididymal bull sperm in vitro. Twelve epididymides (6 bulls) were collected after slaughter and divided into 2 groups, (stored at either 4 or 37�C for 2), after which semen was collected from the caudae epididymides and cryopreserved. Subsequently, one aliquot of the frozen–thawed semen samples was subjected to induced lipid peroxidation with ferrous sulfate and ascorbate (37�C; 2 h), after which tiobarbituric acid-reactive substances (TBARS), as an index of lipid peroxidation, were measured according to a method previously described (Beorlegui et al. 1997 Andrologia 29, 37–42). A second aliquot was used for in vitro fertilization in a routine IVF–IVC setup in duplicate (24-h maturation, SOF culture medium in 5% CO2, 5% O2, and 90% N2). In vitro embryo production results at Day 7 and TBARS levels were statistically analyzed using SAS (SAS Institute, Inc., Cary, NC, USA). No influence of storage temperature was observed at either TBARS level (4�C: 943.6 � 173.4; 37�C: 751.4 � 136.2 ng of TBARS/108 spermatozoa; P = 0.3) or on blastocyst rates (4�C: 23.0 � 2.8; 37�C: 18.7 � 3.6% of blastocysts; P = 0.2). However, the percentage of hatched blastocysts tend to be higher for epididymides stored at 4�C when compared to those stored at 37�C (6.4 � 1.8 and 2.3 � 0.9, respectively; P = 0.06). In addition, a negative correlation was found between TBARS concentrations and blastocyst rates (R = –0.57; P &amp;lt; 0.05). Compared to fresh samples collected from epididymides under the same conditions (unpublished data), levels of TBARS were two- to threefold higher for the cryopreserved sperm, indicating that lipid peroxidation appears to play a role in the decrease in quality of cryopreserved epididymal sperm. In conclusion, temperature during the epididymides short-term storage prior to sperm cryopreservation did not seem to influence the sperms&amp;apos; in vitro fertilizing capacity. On the other hand, an alternative to improve cryopreserved epididymal sperm in vitro fertility (or fertilizing capacity) could be the addition of antioxidants to semen extenders. Further studies are necessary to confirm this hypothesis.

Short-term ascorbic acid deficiency does not impair antioxidant status in lens of guinea pigs.

We examined whether short-term ascorbic acid deficiency impairs antioxidant status in the lens of guinea pigs. Male guinea pigs aged 4 wk were given a scorbutic diet (20 g/animal per day) with and without ascorbic acid (400 mg/animal per day) in drinking water for 3 wk. The ascorbic acid-deficient group showed no lens opacity. The ascorbic acid-deficient group had 14% of serum ascorbic acid concentration, 6% of aqueous humor ascorbic acid concentration, and 18% of lens ascorbic acid content in the ascorbic acid-adequate group. There were no differences in the contents of lens reduced glutathione and thiobarbituric acid reactive substances, an index of lipid peroxidation, between the ascorbic acid-deficient and adequate groups, while the deficient group had higher lens vitamin E content than the adequate group. The ascorbic acid-deficient group had higher serum vitamin E concentration than the ascorbic acid adequate group, while there were no differences in the concentrations of serum reduced glutathione and tiobarbituric acid reactive substances between the deficient and adequate groups. These results indicate that short-term ascorbic acid deficiency does not impair antioxidant status in the lens of guinea pigs despite induction of severe ascorbic acid depletion in the tissue, which may result in no cataract formation.

Influence of dietary carbohydrate on antioxidant enzyme activities in liver of Atlantic salmon (Salmo salar L.)

Effects of dietary carbohydrates on hepatic antioxidant enzymeactivities were studied in Atlantic salmon (Salmo salarL.), fed diets containing no additional carbohydrate, or a low (15% addition)orhigh (30% addition) concentration of D-glucose or gelatinised potato starch.Addition of free glucose to the feeds resulted in glucose availability being 7and 18% when added at 15 and 30%, while the addition of gelatinised starch didnotseem to reduce starch availability. The dietary treatment groups (nocarbohydrate, 7 and 18% glucose or 15 and 30% gelatinised starch) were providedwith quantities of feed that supplied the same amounts of protein and lipid.There was a positive correlation between tiobarbituric acid-reactive substances(TBARS) in feeds and salmon liver. Liver glycogen concentrations increased withincreasing dietary glucose and starch, and the two higher levels of liverglycogen, found in groups G18 and S30, resulted in decreased activities ofcatalase, superoxide dismutase (t-SOD), and concentrations of glutathione. Thisindicates that there are links between carbohydrate metabolism and antioxidantsystems in salmon liver. There was no correlation between selenium dependentglutathione peroxidase (Se-GPX) activity and dietary carbohydrateconcentrations, but Se-GPX activity increased in response to increased TBARS.Catalase and t-SOD activities did not correlate with either TBARS values orSe-GPX activity.

Heat-shock preconditioning reduces oxidative protein denaturation and ameliorates liver injury by carbon tetrachloride in rats

Membrane lipids and cytosolic proteins are major targets of oxidative injury. This study examined the effect of heat-shock preconditioning associated with the induction of heat-shock protein 72 on liver injury, from the aspect of lipid peroxidation and protein denaturation after carbon tetrachloride (CCl4) administration in rats--one of the representative oxidative injuries. Male Wistar rats were divided into two groups, group HS (preconditioned by heat exposure) and group C (not preconditioned). Expression of HSP72 in the liver tissue was confirmed by Western blot analysis. After a 48-h recovery period, all rats were given CCl4 intragastrically. Liver damage was assessed by measuring serum liver-related enzyme levels and adenine nucleotide concentration in the liver tissue. Lipid peroxidation and protein denaturation were evaluated by measuring tiobarbituric acid reactive substances (TBARS) and by immunohistochemical staining of 4-hydroxy-2-nonenal(HNE)-modified proteins in the liver. Survival rates of the rats after CCl4 administration were also compared. Expression of HSP72 was clearly detected in group HS, but not in group C. Heat-shock preconditioning significantly improved the survival rate, suppressed the increase in liver-related enzyme levels and maintained adenosine triphosphate levels (P<0.01 each). HNE-modified proteins--denatured proteins by free radical attack--were significantly less stained in group HS than in group C (P<0.05). However, TBARS levels did not differ between groups. Because heat-shock preconditioning did not alter TBARS levels but reduced HNE-modified proteins in association with the expression of HSP72, it is suggested that HSP72 did not prevent lipid peroxidation but decreased the lipid peroxidation-induced denaturation of proteins. This seemed to be a mechanism of heat-shock preconditioning to ameliorate oxidative liver injury.

Cadmium induced lipid peroxidation in kidney function.

Since the kidney is the main target organ for many metals including cadmium, the generation of the products of lipid peroxidation due to accumulation of these toxic metals in the kidney may have importance in the mechanism of their nephrotoxicity. In order to test this hypothesis, we carried out an experimental study in rats. The functions and the levels of tiobarbituric acid reactive substances (TBARS) of the kidney were investigated in animals receiving 15 micrograms/ml aqueous Cd solution for 30 days. Due to cadmium accumulation in kidney cortex, the ratio of Cd/Zn increased significantly and this increase was associated with elevated TBARS in both renal cortex and medulla. The content of TBARS in renal cortex rose from 211.6 +/- 64.2 to 303.4 +/- 46.4 nmol/g protein (p<0.01) and GFR decreased to 390.5 +/- 109.4 from 1008.7 +/- 4.8 microliters/min (p<0.01) in cadmium exposed animals. Daily coadministration of selenium, vitamins A, C, E did not reverse the adverse effect of cadmium on kidney function, despite the significant decrease in cortex TBARS levels (p<0.01). In conclusion, these data suggest to us that lipid peroxidation assessed by TBA test may not be the only mechanism in cadmium induced nephrotoxicity.