Lipid peroxidation and antioxidant defense enzymes in various regions of adult rat brain after co-exposure to cadmium and ethanol

Evaluation of Hepatoprotective activity of Eriocaulon quinquangulare in vitro using porcine liver slices against ethanol induced liver toxicity and free radical scavenging capacity

BACKGROUND

Production of reactive oxygen species is a common cause in alcohol induced liver diseases. Decoction prepared from the whole plant of Eriocaulon quinquingulare is prescribed to treat liver disorders. The aim of this study was to investigate the hepatoprotective activity and antioxidant capacity of the water extract of E. quinquangulare in vitro.

METHOD

The aqueous extract of the whole plant of E. quinquangulare (AEQ) was investigated for its phytochemical constituents, antioxidant and membrane stabilization properties in-vitro. The antioxidant activities of AEQ were investigated using 1,1-Diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical, nitric oxide scavenging and ferric reducing antioxidant power (FRAP) assays. Membrane stabilizing effect of the extract was determined by hypotonic solution induced human erythrocyte hemolytic assay (HEHA). Further, hepatoprotective activity against ethanol induced hepatotoxicity was carried out using porcine liver slices.

RESULTS

The total phenolics and flavonoids were 10.3 ± 1.6 w/w % gallic acid equivalents and 45.6 ± 3.8 w/w % (-)-epigallocatechin gallate equivalents respectively. The values of EC50 for DPPH, hydroxyl radical and nitric oxide scavenging assays were 37.2 ± 1.7 μg/ml, 170.5 ± 6.6 μg/ml and 31.8 ± 2.2 μg/ml respectively. The reducing capability of AEQ was 6.9 ± 0.2 w/w % L-ascorbic acid equivalents in the FRAP assay. For hypotonic solution induced HEHA, the IC50 was 1.79 ± 0.04 mg/ml. A significant decrease (p < 0.05) was observed in ALT, AST and LDH release from the liver slices treated with AEQ compared to the ethanol treated liver slices. A significant reduction in lipid peroxidation (p < 0.05) was also observed in liver slices treated with the plant extract compared to that of the ethanol treated liver slices.

CONCLUSIONS

The results suggest AEQ possess hepatoprotective activity against ethanol induced liver toxicity of porcine liver slices which can be attributed to antioxidant properties and membrane stabilizing effects caused by the plant material.

Total phenolic, flavonoid contents, in-vitro antioxidant activities and hepatoprotective effect of aqueous leaf extract of Atalantia ceylanica

Background

Decoction prepared from leaves of Atalantia ceylanica is used in traditional medicine in Sri Lanka for the treatment of various liver ailments since ancient times. Lyophilized powder of the water extract of A. ceylanica leaves was investigated for its phytochemical constituents, antioxidant and hepatoprotective activity in-vitro.

Methods

The total phenolic and flavonoid contents were determined using Folin Ciocalteu method and aluminium chloride colorimetric assay respectively. The antioxidant activities of the decoction were investigated using 1,1-Diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical, nitric oxide scavenging assays and ferric ion reducing power assay. Hepatotoxicity was induced on porcine liver slices with ethanol to study hepatoprotective activity. Porcine liver slices were incubated at 37°C with different concentrations of the water extract of A. ceylanica in the presence of ethanol for 2 hours. The hepatoprotective effects were quantified by the leakage of alanine transaminase (ALT), aspartate transaminase (AST) and lactate dehydrogenase (LDH) to the medium. Thiobarbituric acid reactive substances (TBARS) assay was performed to examine the anti-lipid peroxidation activity caused by the plant extract.

Results

The mean ± SD (n =9) for the levels of total phenolics and flavonoids were 4.87 ± 0.89 w/w% of gallic acid equivalents and 16.48 ± 0.63 w/w% of (-)-Epigallocatechin gallate equivalents respectively. The decoction demonstrated high antioxidant activity. The mean ± SD values of EC₅₀ were 131.2 ± 36.1, 48.4 ± 12.1, 263.5 ± 28.3 and 87.70 ± 6.06 μg/ml for DPPH, hydroxyl radical, nitric oxide scavenging assays and ferric ion reducing power assay respectively.

A significant decrease (p <0.05) was observed in ALT, AST and LDH release from porcine liver slices treated with A. ceylanica extract at a concentration of 2 mg/ml in the presence of ethanol (5 M) compared to that of ethanol (5 M) treated slices. Furthermore, a reduction in lipid peroxidation was also observed in liver slices treated with the leaf extract of A. ceylanica (2 mg/ml) compared to that of ethanol induced liver toxicity (p <0.05).

Conclusions

The results suggest that aqueous extract of A. ceylanica exerts hepatoprotective activity against ethanol induced liver toxicity of porcine liver slices which can be attributed to the antioxidant properties possessed by the plant material.

Electronic supplementary material

The online version of this article (doi:10.1186/1472-6882-14-395) contains supplementary material, which is available to authorized users.

Hepatoprotective effect of Platycodon grandiflorum against chronic ethanol-induced oxidative stress in C57BL/6 mice

AIMS

This study was carried out to evaluate the hepatoprotective effect of Platycodon grandiflorum (PG) in ethanol (EtOH)-induced liver damage.

METHODS AND RESULTS

PG treatment (both the total extract and saponin fraction) significantly blocked EtOH-induced oxidative stress through the preservation of activities of antioxidant enzymes in HepG2 cells. Furthermore, while the administration of EtOH to C57BL/6 mice for 6 weeks induced liver damage, along with a significant increase in plasma glutamic oxalacetic transaminase, glutamic pyruvic transaminase, hepatic triglyceride and thiobarbituric acid reactive substance levels, PG treatment significantly decreased glutamic oxalacetic transaminase, glutamic pyruvic transaminase, hepatic triglyceride and thiobarbituric acid reactive substance levels compared with the EtOH-treated control group (p < 0.05). Histological observation by hematoxylin-eosin and oil red O staining in the liver showed more effective inhibition of lipid accumulation in PG-treated groups, as compared to the EtOH-treated control group. Additionally, PG treatments appeared to enhance the activities of superoxide dismutase and catalase in the liver (p < 0.05).

CONCLUSION

These results suggest that PG has a protective effect against EtOH-induced oxidative damage, possibly by inhibition of lipid accumulation and peroxidation through the enhancement of the antioxidant defense system. PG might be useful as a therapeutically potent natural ingredient for the prevention of chronic EtOH-induced oxidative stress and liver damage.

Reactive oxygen species formation and cell death in catalase-deficient tobacco leaf disks exposed to cadmium

The physiological responses of tobacco (Nicotiana tabacum L.) to oxidative stress induced by cadmium were examined with respect to reactive oxygen species (ROS) formation, antioxidant enzymes activities, and cell death appearance in wild-type SR1 and catalase-deficient CAT1AS plants. Leaf disks treated with 100 or 500 microM CdCl(2) increased Evans blue staining and leakage of electrolytes in SR1 or CAT1AS plants, more pronouncedly in the transgenic cultivar, but without evidence of lipid peroxidation in any of the cultivars compared to controls. Cadmium significantly reduced the NADPH oxidase-dependent O (2)(-) formation in a dose dependent manner in SR1 very strongly at 500 microM (to 5% of the activity in the nontreated SR1 leaf disks). In CAT1AS, the NADPH oxidase activity was constitutively reduced at 50% with respect to that of SR1, but the magnitude of the decay was less prominent in this cultivar, reaching an average of 64% of the C at 21 h, for both Cd concentrations. Hydrogen peroxide formation was only slightly increased in SR1 or CAT1AS leaf disks at 21 h of exposure compared to the respective controls. Cd increased superoxide dismutase activity more than six times at 21 h in CAT1AS, but not in SR1 and reduced catalase activity by 59% at 21 h of treatment only in SR1 plants. Despite that catalase expression was constitutively lower in CATAS1 compared to SR1 nontreated leaf disks, 500 microM CdCl(2) almost doubled it only in CAT1AS at 21 h. The mechanisms underlying Cd-induced cell death were possibly not related exclusively to ROS formation or detoxification in tobacco SR1 or CAT1AS plants.

THE EFFECTS OF ETHANOL CONSUMPTION ON THE LIPID PEROXIDATION AND GLUTATHIONE LEVELS IN THE RIGHT AND LEFT BRAINS OF RATS

The effects of ethanol consumption on the levels of lipid peroxidation and reduced glutathione (GSH) in the cerebral hemispheres of male rats were investigated. The rats were randomly divided into eight groups: control, 10%, 25%, 35% ethanol-consuming groups, and four groups given vitamin E. The level of lipid peroxidation increased 34.32% (right brain), 35.67% (left brain) in 10% ethanol-consuming rats; 32.05% (right brain), 31.81% (left brain) in 25% ethanol-consuming rats; and 33.45% (right brain), 39.72% (left brain) in 35% ethanol-consuming rats. The GSH level of the right and left brains significantly decreased: 19.39%, 19.56%; 27.58%, 29.34%; 35.34%, 33.22% in rats consuming 10%, 25%, and 35% ethanol, respectively. These effects were partly antagonized by administration of vitamin E (100 mg/kg/day i.p.) to ethanol-consuming rats for 20 days. The results suggested that the cerebral hemispheres of adult rats are susceptible to the oxidative neurotoxic effects of ethanol, which may be blocked by vitamin E.

Estradiol prevents ozone-induced increases in brain lipid peroxidation and impaired social recognition memory in female rats

There is increasing concern about the neurodegenerative and behavioral consequences of ozone pollution in industrialized urban centers throughout the world and that women may be more susceptible to brain neurodegenerative disorders. In the present study we have investigated the effects of chronic (30 or 60 days) exposure to ozone on olfactory perception and memory and on levels of lipid peroxidation, alpha and beta estrogen receptors and dopamine beta-hydroxylase in the olfactory bulb in ovariectomized female rats. The ability of 17beta-estradiol to prevent these effects was then assessed. Results showed that ozone exposure for 30 or 60 days impaired formation/retention of a selective olfactory recognition memory 120 min after exposure to a juvenile stimulus animal with the effect at 60 days being significantly greater than at 30 days. They also showed impaired speed in locating a buried chocolate reward after 60 days of ozone exposure indicating some loss of olfactory perception. These functional impairments could all be prevented by coincident estradiol treatment. In the olfactory bulb, levels of lipid peroxidation were increased at both 30- and 60-day time-points and numbers of cells with immunohistochemical staining for alpha and beta estrogen receptors, and dopamine beta-hydroxylase were reduced as were alpha and beta estrogen receptor protein levels. These effects were prevented by estradiol treatment. Oxidative stress damage caused by chronic exposure to ozone does therefore impair olfactory perception and social recognition memory and may do so by reducing noradrenergic and estrogen receptor activity in the olfactory bulb. That these effects can be prevented by estradiol treatment suggests increased susceptibility to neurodegenerative disorders in aging women may be contributed to by reduced estrogen levels post-menopause.

Impact of an acute exposure to ethanol on the oxidative stress status in the hippocampus of prenatal restraint stress adolescent male rats

Prenatal restraint stress (PRS) in rats is associated with hippocampal dysfunctions and several behavioural and endocrine disorders related to this brain area. Recently, we have reported that the PRS modifies the hypothalamic-pituitary-adrenal (HPA) response to an ethanol challenge in adolescent animals. Since hippocampus is particularly sensitive to the deleterious effects of ethanol during adolescence, we investigated in this study the combined effects of PRS and ethanol administration on the oxidative status in the hippocampus of 28-day-old male rats. Thirty minutes after an intraperitoneal (i.p.) injection of ethanol (1.5 g/kg), the activities of several antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) but also non-enzymatic antioxidant (reduced glutathione) were assayed. Thiobarbituric acid reactive substances (TBARS) levels were also measured as a marker of lipid peroxidation. Ethanol enhanced superoxide dismutase activity in control rats but not in PRS rats. At basal level, catalase activity was lower in PRS rats than in control rats, indicating a potentially higher sensitivity to oxidative damages after this early stress. However, the hippocampal TBARS levels were not significantly affected by the ethanol administration, showing that an acute ethanol exposure does not induce oxidative damage in adolescent male rats. In conclusion, our data suggest that PRS affects both basal antioxidant status in the hippocampus and antioxidant response after an acute ethanol exposure. These findings extend previous works showing that PRS leads to hippocampal dysfunctions and raise the question of the potential increase of the hippocampal oxidative damage in PRS rats after repeated exposure to ethanol.

Protective effects of mycelia of Antrodia camphorata and Armillariella tabescens in submerged culture against ethanol-induced hepatic toxicity in rats

The hepatoprotective effects of the mycelia of Antrodia camphorata and Armillariella tabescens were evaluated in vivo using acute ethanol-intoxicated rats as an experimental model. Animals were orally treated with Antrodia camphorata (0.5 or 1.0 g/kg b.w.) or Armillariella tabescens (0.5 or 1.0 g/kg b.w.) for 10 days whereas controls received vehicle only. At the end of the experimental 10-day period, the animals were administered by gavage with an acute ethanol dose of 5.0 g/kg b.w. diluted in deionized water (6:4, v/v) and sacrificed at 18 h after ethanol administration. The degree of protection was measured by using biochemical parameters like serum transaminases (AST and ALT), alkaline phosphatase (ALP), bilirubin. Meanwhile, the histopathological studies were carried out to support the above parameters. Administration of Antrodia camphorata or Armillariella tabescens markedly prevented ethanol-induced elevation of levels of serum AST, ALT, ALP, and bilirubin comparable with standard drug silymarin.

Protection of liver cells from ethanol cytotoxicity by curcumin in liver slice culture in vitro

Curcumin, a widely used spice and colouring agent in food has been shown to have a broad spectrum of biological activities such as anti-inflammatory, anti-neoplastic, antimutagenic and antioxidant. We have used liver slice culture model to demonstrate hepatoprotective activity of curcumin in vitro. Ethanol has been used as a hepatotoxin and the cytotoxicity of ethanol is estimated by quantitating the release of LDH. Ethanol induces 3.5 times more release of LDH from the liver cells and twice the amount of lipid peroxidation as compared to the cells from untreated liver tissue and this was significantly reduced in presence of curcumin (5 microM). We measured the activity of antioxidant enzymes (AOEs) namely superoxide dismutase, catalase and peroxidase and found that in ethanol treated cells activity of all three enzymes was elevated. However, when curcumin was added along with ethanol their levels were kept low. The fact that release of LDH is significantly reduced along with lipid peroxidation and the activity of AOEs is kept low indicates that curcumin by its antioxidant activity reduced the oxidative stress induced by ethanol and protected the liver cells in vitro.

Carboplatin-induced oxidative injury in rat inferior colliculus

Carboplatin is currently being used as an anticancer drug against human cancers. However, high dose of carboplatin chemotherapy resulted in ototoxicity in cancer patients. Carboplatin-induced ototoxicity was related to oxidative stress to the cochlea and inner hair cell loss in animals. It is likely that initial oxidative injury spreads throughout the neuroaxis of the auditory system later. The study aim was to evaluate carboplatin-induced hearing loss and oxidative injury to the central auditory system (inferior colliculus) of the rat. Male Wistar rats were divided into two groups of seven animals each and treated as follows: (1) control (normal saline, intraperitoneal [i.p.]) and (2) carboplatin (256 mg/kg, i.p.). Auditory brain-evoked responses (ABRs) were recorded before and 4 days after treatments. The animals were sacrificed on the 4th day and inferior colliculus from brain stem and cerebellum were isolated and analyzed. Carboplatin significantly elevated the hearing threshold shifts at clicks, 2-, 4-, 8-, 16-, and 32-kHz tone burst stimuli. Carboplatin significantly increased nitric oxide and lipid peroxidation, xanthine oxidase, and manganese superoxide dismutase activities in the inferior colliculus, but not in the cerebellum, indicating an enhanced flux of free radicals in the central auditory system. Carboplatin significantly depressed the reduced to oxidized glutathione ratio, antioxidant enzyme activities, such as copper-zinc superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase, and enzyme protein expressions in the inferior colliculus, but not in the cerebellum, 4 days after treatment. The data suggest that carboplatin induced oxidative injury specifically in the inferior colliculus of the rat leading to hearing loss.

Regional responses in antioxidant system to exercise training and dietary Vitamin E in aging rat brain

We have evaluated the effect of exercise, Vitamin E and a combination of both on the antioxidant enzymes (AOEs)-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) along with the products of lipid peroxidation (LP)-malondialdehyde (MDA) and lipofuscin-like auto fluorescent substances (LF-like AFS) in discrete brain regions of rats of 4 (young adults), 8 (old adults), 12 (middle-age) and 22 months (mos) old of age. Hippocampus (HC) showed greater increase in GSH-Px activity than cerebral cortex (CC) to exercise and Vitamin E and was irrespective of the age. A combination of both was effective in the CC of all age groups but not in the supplemented sedentary of 12- and 22-mo-olds. CAT activity increased significantly in the HC of supplemented and trained rats but not in the combination group of any age. SOD increased in both the regions of supplemented trainees. However, old were more benefited in terms of maximal elevation in the HC. Vitamin E reduced MDA content in both regions of adult. LF-like AFS decreased significantly in supplemented sedentary and trainees of all ages. Our results demonstrate that an age-related deficit in AOEs in the CC and HC can be overcome through Vitamin E plus exercise, and further suggests the rationale for looking at these markers of oxidative stress in several age-related neuronal diseases.

Lack of prion protein expression results in a neuronal phenotype sensitive to stress

The prion protein is a highly conserved glycoprotein expressed most highly in the synapse. Evidence has recently been put forward to suggest that the prion protein is an antioxidant. However, the functional importance of the prion protein has been disputed; it is claimed that mice genetically ablated to lack prion protein expression are normal and have no specific phenotype. We have reexamined the phenotype of prion protein knockout mice and found that there are multiple biochemical changes in the mice, including increased levels of nuclear factor NF-kappaB and Mn superoxide dismutase, COX-IV decreased levels of Cu/Zn superoxide dismutase activity, decreased p53, and altered melatonin levels. Additionally, cultured cells from these mice are more sensitive to a range of insults, all linked to increased neuronal sensitivity to oxidative stress. These results imply that prion protein knockout mice are more sensitive to oxidative stress and have an altered phenotype that must be taken into account when considering the additional effects of increased levels of proteins such as Doppel. The implication of these results is that the consequence of genetic ablation of genes must include biochemical analysis as well as analyses of possible developmental and behavioral changes.

Cadmium-dependent enzyme activity alteration is not imputable to lipid peroxidation

The effect of cadmium on the liver-specific activities of NADPH-cytochrome P450 reductase (CPR), malic dehydrogenase (MDH), glyceraldehyde-3-phosphate dehydrogenase (GADPH), and sorbitol dehydrogenase (SDH) was assessed 6, 24, and 48 h after administration of the metal to rats (2.5 mg/kg of body weight, as CdCl2, single ip injection). CPR specific activity increased after 6 h and afterward decreased significantly, while MDH specific activity increased up to 24 h and then remained unchanged. Both SDH and GADPH specific activities reduced after 6 h, the former only a little but the latter much more, and after 24 and 48 h were strongly inhibited. In vitro experiments, by incubating rat liver microsomes, mitochondria, or cytosol with CdCl2 in the pH range 6.0-8.0, excluded cadmium-induced lipid peroxidation as the cause of the reduction in enzyme activity. In addition, from these experiments, we obtained indications on the type of interactions between cadmium and the enzymes studied. In the case of CPR, the inhibitory effect is probably due to Cd2+ binding to the histidine residue of the apoenzyme, which, at physiological pH, acts as a nucleophilic group. In vitro, mitochondrial MDH was not significantly affected by cadmium at any pH, indicating that this enzyme is probably not involved in the decrease in mitochondrial respiration caused by this metal. As for GADPH specific activity, its inhibition at pH 7.4 and above is imputable to the binding of cadmium to the SH groups present in the enzyme active site, since in the presence of dithiothreitol this inhibition was removed. SDH was subjected to a dual effect when cytosol was exposed to cadmium. At pH 6.0 and 6.5, its activity was strongly stimulated up to 75 microM CdCl2 while at higher metal concentrations it was reduced. At pH 7.4 and 8.0, a stimulation up to 50 microM CdCl2 occurred but above this concentration, a reduction was found. These data seem to indicate that cadmium can bind to different enzyme sites. One, at low cadmium concentration, stimulates the SDH activity while the other, at higher metal concentrations, substitutes for zinc, thus causing inhibition. This last possibility seems to occur in vivo essentially at least 24 h after intoxication. The cadmium-induced alterations of the investigated enzymes are discussed in terms of the metabolic disorders produced which are responsible for several pathological conditions.

Neurobehavioural effects of occupational exposure to cadmium: a cross sectional epidemiological study

BACKGROUND

A patient with unexplained minor behavioural changes associated with an axonal sensorimotor polyneuropathy had a history of chronic occupational exposure to cadmium (Cd). Although animal studies have shown that Cd is a potent neurotoxicant, little is known about its toxicity for the human central nervous system. The aim of this study was to investigate the toxic potential of chronic occupational exposure to Cd on neurobehavioural functions.

METHODS

A cross sectional epidemiological study was conducted ina group of Cd workers and an age matched control group. Eighty nine adult men (42 exposed to Cd and 47 control workers) were given a blinded standardised examination that consisted of computer assisted neurobehavioural tests (neurobehavioural examination system), a validated questionnaire to assess neurotoxic complaints (neurotoxicity symptom checklist--60, NSC-60), and a standardised self administered questionnaire to detect complaints consistent with peripheral neuropathy and dysfunction of the autonomic nervous system. Historical and current data on biomonitoring of exposure to Cd, either the highest value of Cd in urine (CdU in microgram Cd/g creatinine) of each Cd worker during work (CdUmax) or the current value (CdUcurrent) of each control, were available as well as data on microproteinuria.

RESULTS

Cd workers (CdUmax: mean (range), 12.6 (0.4-38.4)) performed worse than the controls (CdUcurrent: mean (range), 0.7 (0.1-2.0)) on visuomotor tasks, symbol digit substitution (p = 0.008), and simple reaction time to direction (p = 0.058) or location (p = 0.042) of a stimulus. In multiple linear regression analysis, symbol digit substitution, simple direction reaction time test, and simple location reaction time test were significantly related to CdUmax, (beta = 0.35 (p < 0.001), beta = 0.25 (p = 0.012), and beta = 0.23 (p = 0.021) respectively). More complaints consistent with peripheral neuropathy (p = 0.004), complaints about equilibrium (p = 0.015), and complaints about concentration ability (p = 0.053) were found in the group exposed to Cd than in the control group, and these variables correlated positively with CdUmax (peripheral neuropathy: beta = 0.38, p < 0.001; equilibrium: beta = 0.22, p = 0.057; concentration ability: beta = 0.27, p = 0.020).

CONCLUSION

Slowing of visuomotor functioning on neurobehavioural testing and increase in complaints consistent with peripheral neuropathy, complaints about equilibrium, and complaints about concentration ability were dose dependently associated with CdU. Age, exposure to other neurotoxicants, or status of renal function could not explain these findings. The present study also indicates that an excess of complaints may be detected in Cd workers before signs of microproteinuria induced by Cd occur.

Ethanol potentiates lead-induced inhibition of rat brain antioxidant defense systems

We investigated the effect of alcohol (3 g/kg body weight intragastrically) on lead-induced (50 mg/kg body weight intragastrically) oxidative stress in adult rat brain. Ethanol was found to potentiate the accumulation of lead in the rat brain by 100%. Lead and ethanol in combination also enhanced lipid peroxidation, a deteriorative process of biomembranes, and markedly decreased the antioxidant capacity of neuronal cells in terms of reduced activities of antioxidant enzymes i.e., superoxide dismutase, catalase and glutathione peroxidase. Further, the activity of glutathione reductase was also significantly decreased in lead and ethanol co-exposed animals as compared to only lead-treated animals, which had altered glutathione status. The results of the present study show that ethanol makes the adult rat brain more susceptible to the neurotoxic effects of lead by accentuating the oxidative stress induced by lead.

Prion protein expression and superoxide dismutase activity

The function of the prion protein (PrPc) remains uncertain. It has been suggested that prion protein expression may aid cellular resistance to oxidative stress by influencing the activity of Cu/Zn superoxide dismutase (Cu,Zn SOD). The activity of Cu,Zn SOD was investigated in mice with different levels of PrPc expression. Increasing levels of PrPc expression were linked to increased levels of Cu,Zn SOD activity. Western-blot and Northern-blot analysis indicated that mice either lacking or overexpressing PrPc had levels of Cu,Zn SOD mRNA equivalent to those expressed in wild-type mice. Mice overexpressing the prion protein had lower levels of resistance to oxidative stress but higher expression levels of glutathione peroxidase, probably due to increased levels of hydrogen peroxide produced by increased Cu,Zn SOD activity. When cells were metabolically labelled with radioactive copper, increased radioactivity was immunoprecipitated with Cu,Zn SOD from mice with higher levels of PrPc. In addition, diethyldithiocarbamate, a copper chelator that inactivates Cu,Zn SOD by capturing copper from the molecule, is more able to inactivate Cu,Zn SOD expressed in animals with higher levels of PrPc. As recent studies have suggested that PrPc may regulate some aspect of copper metabolism, it is suggested that PrPc expression may regulate Cu,Zn SOD activity by influencing copper incorporation into the molecule.

Influence of exercise and ethanol on cholinesterase activity and lipid peroxidation in blood and brain regions of rat

1. This study elucidates the interaction of acute exercise and single ethanol intake on cholinergic enzyme and its relationship to lipid peroxidation in the blood and brain regions of the rat. 2. Butyrylcholinesterase (BuChE) in plasma and acetylcholinesterase (AChE) in brain regions as well as lipid peroxidation (MDA) were assayed in 1) sedentary control rats; 2) after acute exercise (100% VO2max); 3) ethanol 20% (1.6 gm/kg, p.o.); 4) exercise and then ethanol 20% (1.6 gm/kg, p.o.). 3. Acute exercise significantly increased BuChE activity (155% of control) in plasma and decreased AChE activity (60% of control) in the corpus striatum with a significant increase in the striatal MDA level (254% of control). Ethanol significantly decreased AChE activity only in striatum (86% of control) with a significant increase in striatal MDA level (132% of control). 4. The combination of exercise and ethanol 20% (1.6 gm/kg, p.o.) significantly increased BuChE activity (123% of control) in plasma, and decreased AChE activity (76% of control) in striatum with significant increase in striatal MDA level (147% of control). 5. Acute exercise, single ethanol 20% (1.6 gm/kg, p.o.) intake and the combination selectively inhibited striatal AChE, and the inhibition was correlated with increased lipid peroxidation indicating perturbation of motor function. The combination reduced the peripheral stress response caused by exhaustive exercise.

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.

Role of intracellular Cd2+ in catecholamine release and lethality in PC12 cells

To evaluate the role of intracellular Cd2+ in catecholamine release and lethality in rat pheochromocytoma (PC12) cells the following results were obtained: [1] the presence of Cd2+ intracellularly was demonstrated with the Cd(2+)-sensitive fluorescent dye BTC-5N, [2] Cd2+ entry through Ca(2+)-channels was either blocked with nifedipine or diltiazem or increased with Bay K8644, [3] Cd2+ entry through voltage sensitive Ca2+ channels was related to dopamine release and cell lethality, [4] a calmodulin inhibitor protected against Cd2+ toxicity, and [5] extracellular Ca2+ concentration, altered prior to Cd2+ exposure, was inversely related to dopamine release by Cd2+. The data indicate intracellular effects of Cd2+ rather than cell surface actions are primarily involved in neurotransmitter release and lethality by toxic levels of Cd2+ in adrenomedullary cells. To evaluate the role of intracellular Cd2+ in catecholamine release and lethality in rat pheochromocytoma (PC12) cells the following results were obtained: [1] the presence of Cd2+ intracellularly was demonstrated with the Cd(2+)-sensitive fluorescent dye BTC-5N, [2] Cd2+ entry through Ca(2+)-channels was either blocked with nifedipine or diltiazem or increased with Bay K8644, [3] Cd2+ entry through voltage sensitive Ca2+ channels was related to dopamine release and cell lethality, [4] a calmodulin inhibitor protected against Cd2+ toxicity, and [5] extracellular Ca2+ concentration, altered prior to Cd2+ exposure, was inversely related to dopamine release by Cd2+. The data indicate intracellular effects of Cd2+ rather than cell surface actions are primarily involved in neurotransmitter release and lethality by toxic levels of Cd2+ in adrenomedullary cells.