Age-related changes in antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione in different regions of mouse brain

Effect of selenium supplementation on glutathione peroxidase and catalase activities in senescent cultured human fibroblasts

AIMS

To investigate the effect of senescence and selenium supplementation on glutathione peroxidase (cGPx) and catalase (CAT) activities, and concurrent hydrogen peroxide (H(2)O(2)) generation in subcultured human fibroblasts.

METHODS

cGPx and CAT activities and H(2)O(2) levels were assayed in presenescent passage 5 and 10 cells, and in senescent passage 20, 25, 30 and 35 cells cultured in routine medium (MEM1) and supplemented media MEM2 and MEM3 containing normal and triple human plasma levels of Se, respectively. Senescent cells were identified by studying their growth and replication states, and by monitoring their activity of key glucose and glycogen degradative enzymes.

RESULTS

cGPx activity showed moderate increases in senescent cells at passages 20-35 subcultured in MEM1 or MEM2. This activity underwent highly significant progressive increases in the same senescent cells subcultured in MEM3. In contrast, CAT activity showed progressive, highly significant increases in senescent cells at passages 20-35 regardless of the culture medium type. Concurrent H(2)O(2) generation was significantly increased in passage 15-25 cells and peaked to higher levels in passage 30 and 35 cells cultured in MEM1 or MEM2. These rates, however, were significantly reduced in senescent passage 20-35 cells cultured in MEM3.

CONCLUSIONS

The highest cGPx activity and coupled lower H(2)O(2) generation were achieved in senescent cells cultured in MEM3.

Mitochondrial peptidase IMMP2L mutation causes early onset of age-associated disorders and impairs adult stem cell self-renewal

Mitochondrial reactive oxygen species (ROS) are proposed to play a central role in aging and age-associated disorders, although direct in vivo evidence is lacking. We recently generated a mouse mutant with mutated inner mitochondrial membrane peptidase 2-like (Immp2l) gene, which impairs the signal peptide sequence processing of mitochondrial proteins cytochrome c1 and glycerol phosphate dehydrogenase 2. The mitochondria from mutant mice generate elevated levels of superoxide ion and cause impaired fertility in both sexes. Here, we design experiments to examine the effects of excessive mitochondrial ROS generation on health span. We show that Immp2l mutation increases oxidative stress in multiple organs such as the brain and the kidney, although expression of superoxide dismutases in these tissues of the mutants is also increased. The mutants show multiple aging-associated phenotypes, including wasting, sarcopenia, loss of subcutaneous fat, kyphosis, and ataxia, with female mutants showing earlier onset and more severe age-associated disorders than male mutants. The loss of body weight and fat was unrelated to food intake. Adipose-derived stromal cells (ADSC) from mutant mice showed impaired proliferation capability, formed significantly less and smaller colonies in colony formation assays, although they retained adipogenic differentiation capability in vitro. This functional impairment was accompanied by increased levels of oxidative stress. Our data showed that mitochondrial ROS is the driving force of accelerated aging and suggested that ROS damage to adult stem cells could be one of the mechanisms for age-associated disorders.

Role of oxidative stress in epileptic seizures

Oxidative stress resulting from excessive free-radical release is likely implicated in the initiation and progression of epilepsy. Therefore, antioxidant therapies aimed at reducing oxidative stress have received considerable attention in epilepsy treatment. However, much evidence suggests that oxidative stress does not always have the same pattern in all seizures models. Thus, this review provides an overview aimed at achieving a better understanding of this issue. We summarize work regarding seizure models (i.e., genetic rat models, kainic acid, pilocarpine, pentylenetetrazol, and trimethyltin), oxidative stress as an etiologic factor in epileptic seizures (i.e., impairment of antioxidant systems, mitochondrial dysfunction, involvement of redox-active metals, arachidonic acid pathway activation, and aging), and antioxidant strategies for seizure treatment. Combined, this review highlights pharmacological mechanisms associated with oxidative stress in epileptic seizures and the potential for neuroprotection in epilepsy that targets oxidative stress and is supported by effective antioxidant treatment.

Pre and post-natal exposure to ambient level of air pollution impairs memory of rats: the role of oxidative stress

The aims of this study were to evaluate whether air pollution during pre-natal and post-natal phases change habituation and short-term discriminative memories and if oxidants are involved in this process. As secondary objectives, it was to evaluate if the change of filtered to nonfiltered environment could protect the cortex of rats against oxidative stress as well as to modify the behavior of these animals. Wistar, male rats were divided into four groups (n = 12/group): pre and post-natal exposure until adulthood to filtered air (FA); pre-natal period to nonfiltered air (NFA-FA); until (21st post-natal day) and post-natal to filtered air until adulthood (PND21); pre-natal to filtered air until PND21 and post-natal to nonfiltered air until adulthood (FA-NFA); pre and post-natal to nonfiltered air (NFA). After 150 days of air pollution exposure, animals were tested in the spontaneous object recognition test to evaluate short-term discriminative and habituation memories. Rats were euthanized; blood was collected for metal determination; cortex dissected for oxidative stress evaluation. There was a significant increase in malondialdehyde (MDA) levels in the NFA group when compared to other groups (FA: 1.730 +/- 0.217; NFA-FA: 1.101 +/- 0.217; FA-NFA: 1.014 +/- 0.300; NFA: 5.978 +/- 1.920 nmol MDA/mg total proteins; p = 0.007). NFA group presented a significant decrease in short-term discriminative (FA: 0.603 +/- 0.106; NFA-FA: 0.669 +/- 0.0666; FA-NFA: 0.374 +/- 0.178; NFA: -0.00631 +/- 0.106 sec; p = 0.006) and an improvement in habituation memories when compared to other groups. Therefore, exposure to air pollution during both those periods impairs short-term discriminative memory and cortical oxidative stress may mediate this process.

'The effect of micronutrients on superoxide dismutase in senescent fibroblasts'

The specific activities of zinc/copper (Zn/Cu)-superoxide dismutase (SOD-1) and manganese (Mn)-superoxide dismutase (SOD-2) were assayed in young passage 5 fibroblasts and in serially subcultured cells that were characterized as senescent at passages 15-35. SOD-1 and SOD-2 activities did not significantly change in senescent and young cells cultured in either routine medium [minimum essential medium 1 (MEM1)], or in Zn, Cu and Mn supplemented medium (MEM2) containing normal human plasma levels of the cations. SOD-1 and SOD-2 activities, however, underwent parallel progressive significant activity increases in senescent passage 20 and 25 cells, which peaked in value in passage 30 and 35 cells subcultured in supplemented medium (MEM3) containing triple human plasma levels of the cations. Concurrently, superoxide radical generation rates underwent progressive significant increases in senescent passage 15-25 cells, which peaked in value in passage 30 and 35 cells subcultured in MEM1 or MEM2. These rates, however, were significantly lowered in senescent cells subcultured in MEM3. We infer that it was only possible to significantly stimulate SOD-1 and SOD-2 activities in senescent MEM3 cultured cells enabling them to combat oxidative stress.

Acute administration of 5-oxoproline induces oxidative damage to lipids and proteins and impairs antioxidant defenses in cerebral cortex and cerebellum of young rats

5-Oxoproline accumulates in glutathione synthetase deficiency, an autossomic recessive inherited disorder clinically characterized by hemolytic anemia, metabolic acidosis, and severe neurological symptoms whose mechanisms are poorly known. In the present study we investigated the effects of acute subcutaneous administration of 5-oxoproline to verify whether oxidative stress is elicited by this metabolite in vivo in cerebral cortex and cerebellum of 14-day-old rats. Our results showed that the acute administration of 5-oxoproline is able to promote both lipid and protein oxidation, to impair brain antioxidant defenses, to alter SH/SS ratio and to enhance hydrogen peroxide content, thus promoting oxidative stress in vivo, a mechanism that may be involved in the neuropathology of gluthatione synthetase deficiency.

Effects of ubiquinone on hydroperoxide concentration and antioxidant enzymatic activities in the rat hippocampus during pilocarpine-induced seizures

Recent researches have shown that antioxidant compounds may have certain neuroprotective effect against the neurotoxicity of seizures at cellular level. Ubiquinone (UQ), an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. The objective of the present study was to evaluate the neuroprotective effects of UQ in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with either 0.9% saline (i.p., control group), UQ (5, 10 or 20 mg/kg, i.p., UQ5, UQ10 and UQ20 groups), pilocarpine (400 mg/kg, i.p., P400 group), or co-administration of pilocarpine with UQ group rats 30 min prior to UQ administration. After the treatments all groups were observed for 24 h. The antioxidant enzymatic activities as well as the hydroperoxide concentrations were measured using spectrophotometric methods and the results were analyzed. In pilocarpine group there was a significant increase in hydroperoxides concentration and glutathione peroxidase activity. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the hydroperoxide content and increased the superoxide dismutase, catalase and glutathione peroxidase activities in rat hippocampus during seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, which indicates that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences. Our result also suggests that ubiquinone can exert significant neuroprotective effects that might be useful in the treatment of neurodegenerative diseases.

Effects of acrylonitrile on antioxidant status of different brain regions in rats

While the adverse effects of acrylonitrile (AN) on the central nervous system (CNS) are known to be mediated, at least in part, by the generation of free radicals and oxidative stress, there is a paucity of data on region-specific alterations in biomarkers of oxidative stress in the brain of AN-exposed animals. The present study was designed to examine the effects of AN on biomarkers of oxidative stress in several brain regions of adult Sprague-Dawley rats. Daily intraperitoneal (i.p.) treatment of animals to 0 (control, normal saline solution), 25, 50 or 75mgAN/kg body weight for 7 days resulted in statistically significant (p<0.05) increases in the levels of lipid peroxidation product, malondialdehyde (MDA), in the cortex and cerebellum; a statistically significant (p<0.05) decrease MDA levels were noted in the striatum. Contents of reduced glutathione (GSH) were significantly (p<0.05) decreased in cortex, cerebellum and hippocampus. The activities of the antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were differentially affected by AN and these effects were brain region-specific and AN dose-dependent. Taken together, these data suggest brain region-specific effects of AN on lipid peroxidation, activities of antioxidant enzymes and non-enzymatic antioxidant levels. These effects may provide biochemical evidence for AN-induced neurobehavioral damage and disturbance of monoamine neurotransmitters.

Antioxidative potential of melatonin against mercury induced intoxication in spermatozoa in vitro

Mercury is one of the most investigated natural elements and potential contaminants in the environment. Antioxidants have long been known to reduce the free radical-induced oxidative damage. Considering the antioxidant properties of melatonin, this study was aimed to evaluate the effect of melatonin on antioxidant system of rat epididymal sperm in vitro. Sperm samples were dispersed in RPS medium (pH 6.9) and incubated with mercury in the form of mercuric chloride (MC) at three different concentrations (1 microM, 10 microM, 100 microM), melatonin (MLT) at a concentration (100 microM) and mercuric chloride+melatonin (100 microM each) for 3h at 32 degrees C. Sperm viability and motility were assessed every 30 min during the 3-h incubation period. An aliquot of sperm sample was homogenised, centrifuged and used for the assay of superoxide dismutase, glutathione peroxidase, glutathione reductase, TBARS assay to detect lipid peroxidation and hydrogen peroxide generation assay. Samples treated with mercury showed a dose-dependent decrease in motility while there was no significant decrease in sperm viability. In mercury-incubated sperm, the activity of superoxide dismutase, glutathione peroxidase and glutathione reductase decreased significantly while TBARS levels and H2O2 generation were increased in a dose-dependent manner. Co-incubation of sperm with mercury and melatonin exhibited no significant changes in the levels of motility, viability and antioxidant indices as compared to untreated controls. The results suggest that graded doses of mercury elicit depletion of antioxidant defense system in sperm without altering the viability and melatonin treatment was found to significantly inhibit oxidative damage caused by mercury.

Evidence for oxidative stress in tissues derived from succinate semialdehyde dehydrogenase-deficient mice

Animal models of inborn errors of metabolism are useful for investigating the pathogenesis associated with the corresponding human disease. Since the mechanisms involved in the pathophysiology of succinate semialdehyde dehydrogenase (SSADH) deficiency (Aldh5a1; OMIM 271980) are still not established, in the present study we evaluated the tissue antioxidant defences and lipid peroxidation in various cerebral structures (cortex, cerebellum, thalamus and hippocampus) and in the liver of SSADH-deficient mice. The parameters analysed were total radical-trapping antioxidant potential (TRAP) and glutathione (GSH) levels, the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as thiobarbituric acid-reactive substances (TBARS). We first observed that the tissue nonenzymatic antioxidant defences were significantly reduced in the SSADH-deficient animals, particularly in the liver (decreased TRAP and GSH) and in the cerebral cortex (decreased GSH), as compared to the wild-type mice. Furthermore, SOD activity was significantly increased in the liver and cerebellum, whereas the activity of CAT was significantly higher in the thalamus. In contrast, GPx activity was significantly diminished in the hippocampus. Finally, we observed that lipid peroxidation (TBARS levels) was markedly increased in the liver and cerebral cortex, reflecting a high lipid oxidative damage in these tissues. Our data showing an imbalance between tissue antioxidant defences and oxidative attack strongly indicate that oxidative stress is involved in the pathophysiology of SSADH deficiency in mice, and likely the corresponding human disorder.

The spatio-temporal expression pattern of cytoplasmic Cu/Zn superoxide dismutase (SOD1) mRNA during mouse embryogenesis

The cytoplasmic Cu/Zn-superoxide dismutase (SOD1) represents along with catalase and glutathione peroxidase at the first defense line against reactive oxygen species in all aerobic organisms, but little is known about its distribution in developing embryos. In this study, the expression patterns of SOD1 mRNA in mouse embryos were investigated using real-time RT-PCR and in situ hybridization analyses. Expression of SOD1 mRNA was detected in all embryos with embryonic days (EDs) 7.5-18.5. The signal showed the weakest level at ED 12.5, but the highest level at ED 15.5. SOD1 mRNA was expressed in chorion, allantois, amnion, and neural folds at ED 7.5 and in neural folds, notochord, neuromeres, gut, and primitive streak at ED 8.5. In central nervous system, SOD1 mRNA was expressed greatly in embryos of EDs 9.5-11.5, but weakly in embryos of ED 12.5. At EDs 9.5-12.5, the expression of SOD1 mRNA was high in sensory organs such as tongue, olfactory organ (nasal prominence) and eye (optic vesicle), while it was decreased in ear (otic vesicle) after ED 10.5. In developing limbs, SOD1 mRNA was greatly expressed in forelimbs at EDs 9.5-11.5 and in hindlimbs at EDs 10.5-11.5. The signal increased in liver, heart and genital tubercle after ED 11.5. In the sections of embryos after ED 13.5, SOD1 mRNA was expressed in various tissues and especially high in mucosa and metabolically active sites such as lung, kidney, stomach, and intestines and epithelial cells of skin, whisker follicles, and ear and nasal cavities. These results suggest that SOD1 may be related to organogenesis of embryos as an antioxidant enzyme.

The effect of sulfur dioxide inhalation on active avoidance learning, antioxidant status and lipid peroxidation during aging

The effect of SO2 was examined on active avoidance learning, thiobarbituric acid reactive substances (TBARS), and the activities of Cu, Zn superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in young (3 months), middle-age (12 months ), and old (24 months) Swiss male albino rats. Ten ppm SO2 was administered to the animals of SO2 groups in an exposure chamber for 1 h/day x 7 days/week x 6 weeks while control groups were exposed to filtered air in the same condition. The most prominent effect of aging on active performance was also observed in the older group. SO2 exposure significantly decreased the active avoidance learning in the young group, but it had no effect on this parameter in the middle-aged and the older group compared with their corresponding control groups. SO2 exposure resulted in increased levels of Cu, Zn-SOD activity while decreased level of GSH-Px activity in all experimental groups compared with their corresponding control groups. CAT activities were unaltered. TBARS levels of all SO2 exposed groups were significantly increased compared with their respective control groups. In conclusion, results from the present research showed that SO2 exposure resulted in an increase in the lipid peroxidation and caused alterations in antioxidant enzyme activities. Additionally, SO2 exposure impaired cognitive function only in the young rats during the acquisition phase of active avoidance learning.

Cocaine-induced oxidative stress precedes cell death in human neuronal progenitor cells

By 2003, an estimated 34 million Americans had used cocaine according to the National Survey on Drug Use & Health. About 5.9 million of those had used in the past 12 months. Chronic cocaine users often develop addiction, dependency and tolerance to the drug. The psychological and physical effects of cocaine are due to the disruption of the limbic system in the central nervous system (CNS). Increased oxidative stress reported in the frontal cortex and the striatum of rats exposed to cocaine suggests that oxidative damage plays a significant role in cocaine-induced disruption of the CNS. Although it is evident that cocaine induces oxidative stress in the CNS, little has been learned about whether such increased oxidative stress is also relevant to apoptosis in cocaine-exposed models. To gain insight into the role of cocaine-induced oxidative stress in apoptosis, we hypothesized that oxidative stress precedes cell death when cocaine is administrated. To test this hypothesis, we have monitored the oxidative stress and apoptotic effects of acute cocaine exposure in human neuronal progenitor cells (HNPC). We found that oxidative stress was significantly increased at 48h after a 30min cocaine exposure compared to control cells, and that this was followed by cell death at 72h. Using the same experimental paradigm we have previously shown that pro-inflammatory genes are up-regulated in cocaine-exposed HNPC at 24h. Therefore, we suggest that the increased oxidative stress (possibly mediated by inflammatory responses) precedes cell death in cocaine-exposed HNPC. This may have implications for the consequences of cocaine abuse in situations where antioxidant capacity is compromised, as in the aging brain.

Sensitivity of cerebellar glutathione system to neonatal ionizing radiation exposure

Reactive oxygen species (ROS) are relevant components of living organisms that, besides their role in the regulation of different important physiological functions, when present in excess are capable to affect cell oxidative status, leading to damage of cellular molecules and disturbance of normal cell function. ROS accumulation has been associated with a variety of conditions such as neurodegenerative diseases and ionizing radiation exposure. Cell ability to counteract ROS overproduction depends on the capacity of the endogenous antioxidant defenses--which includes the glutathione (GSH) system--to cope with. Since developing central nervous system (CNS) is especially sensitive to ROS-induced damage, the aim of the present work was to evaluate ROS, reduced GSH and oxidized glutathione (GSSG) levels in the cerebellum at different developmental ages after irradiation, in order to test if any changes were induced on these key oxidative stress-related cellular markers that might explain the high cerebellar vulnerability to radiation-induced injury. Since intracellular levels of GSH are maintained by glutathione reductase (GSHr), this enzymatic activity was also evaluated. Newborn Wistar rats were irradiated in their cephalic ends and the different parameters were measured, from 1h to 90 days post-irradiation. Results showed that an early transient increase in ROS levels followed by a decrease in cerebellar weight at 3-5 days post-irradiation were induced. An increase in cerebellar GSH levels was induced at 30 days after irradiation, together with a decrease in GSHr activity. These results support the hypothesis that ROS may represent a marker of damage prior to radiation-induced cell death. In contrast, it would be suggested that GSH system might play a role in the compensatory mechanisms triggered to counteract radiation-induced cerebellar damage.

Redox control of neural function: background, mechanisms, and significance

The redox environment within neural cells is dependent on a series of redox couples. The glutathione disulfide/ glutathione (GSSG/GSH) redox pair forms the major redox couple in cells and as such plays a critical role in regulating redox-dependent cellular functions. Not only does GSH act as an antioxidant but it also can modulate the activity of a variety of different proteins via S-glutathionylation of cysteine sulfhydryl groups. The thioredoxin system also makes a significant contribution to the redox environment by reducing inter- and intrachain protein disulfide bonds as well as maintaining the activity of important antioxidant enzymes such as peroxiredoxins and methionine sulfoxide reductases. The redox environment affects the activity and function of a number of different protein phosphatases, protein kinases, and transcription factors. The sum of these effects will determine how changes in the redox environment alter overall cellular function, thereby playing a fundamental role in regulating neural cell fate and physiology.

Age-related changes in glutathione and glutathione-related enzymes in rat brain

The most reliable and robust risk factor for some neurodegenerative diseases is aging. It has been proposed that processes of aging are associated with the generation of reactive oxygen species and a disturbance of glutathione homeostasis in the brain. Yet, aged animals have rarely been used to model the diseases that are considered to be age-related such as Parkinson's or Alzheimer's disease. This suggests that the results from these studies would be more valuable if aged animals were used. The present study was designed to provide insight into the glutathione redox state in young and aged rat siblings of both genders by studying the enzyme activities related to glutathione synthesis, cycling, and usage. The results suggested a significant age-related reduction of reduced glutathione (GSH) level in all brain regions examined, associated with an increase of GSH oxidation to glutathione disulfide (GSSG) and decrease of the GSH/GSSG ratio. These changes were accompanied by diminished gamma-glutamylcysteine synthetase activity in de novo glutathione synthesis and increased lipid peroxidation. In addition, these changes were associated with increased enzyme activities related to the GSH usage (glutathione peroxidase, gamma-glutamyl transpeptidase, and glutathione S-transferase). The results indicate that aged animals are likely more vulnerable to oxidative stress and insinuate the roles of aged animals in modeling age-related neurodegeneration diseases.

Cadmium induces reactive oxygen species generation and lipid peroxidation in cortical neurons in culture

Cadmium is a toxic agent that it is also an environmental contaminant. Cadmium exposure may be implicated in some humans disorders related to hyperactivity and increased aggressiveness. This study presents data indicating that cadmium induces cellular death in cortical neurons in culture. This death could be mediated by an apoptotic and a necrotic mechanism. The apoptotic death may be mediated by oxidative stress with reactive oxygen species (ROS) formation which could be induced by mitochondrial membrane dysfunction since this cation produces: (a) depletion of mitochondrial membrane potential and (b) diminution of ATP levels with ATP release. Necrotic death could be mediated by lipid peroxidation induced by cadmium through an indirect mechanism (ROS formation). On the other hand, 40% of the cells survive cadmium action. This survival seems to be mediated by the ability of these cells to activate antioxidant defense systems, since cadmium reduced the intracellular glutathione levels and induced catalase and SOD activation in these cells.

The role of phase II antioxidant enzymes in protecting memory T cells from spontaneous apoptosis in young and old mice

Aging is associated with a functional decline and change in the phenotypic distribution of T cell subsets. The free radical theory of aging is widely promoted as the mechanistic basis for cellular senescence, including the immune system. Although the exact molecular explanation for the role of oxidative stress in cellular senescence is unclear, there is a connection to altered mitochondrial function, both as a contributor and as a target of oxidative stress. In this study we demonstrate that splenic T lymphocytes from old C57BL/6 mice exhibit a significant decline in mitochondrial membrane potential (deltapsi(m)). However, despite this change, there is a lower rate of withdrawal apoptosis in the memory CD4+ and CD8+ T cells. To explain the survival of these long-lived cells against a background of increased oxidative stress, we demonstrate increased glutathione production and phase II enzyme expression, which combine to protect memory T cells against oxidative stress, mitochondrial dysfunction, and cell death. The accumulation of memory T cells with aging explains higher phase II enzyme expression in CD4+ and CD8+ T cells from old mice. Compared with wild-type mice, mice lacking the expression of NF-E2-related factor-2, the transcription factor that regulates phase II enzyme expression, had a significantly enhanced rate of apoptosis in the presence of an oxidative stress stimulus. NF-E2-related factor-2-deficient T cells exhibit a bigger decline in deltapsi(m) and increased reactive oxygen species production than cells from wild-type animals. Taken together, we suggest that phase II enzyme expression and the accompanying increase in intracellular thiol levels protect memory T cells from mitochondrial dysfunction and spontaneous apoptosis.

Hexachlorocyclohexane differentially alters the antioxidant status of the brain regions in rat

Hexachlorocyclohexane (HCH), a highly persistent organochlorine insecticide, is neurotoxic at acute doses and causes degenerative effects on chronic exposure. HCH has been reported to induce oxidative stress in cells and tissues. Mammalian brain is sensitive to oxidative stress which is implicated in neurodegenerative diseases. Effect of HCH on the brain regions, cortex, cerebellum, midbrain and brainstem, has been investigated by studying the response of antioxidant enzymes in rats treated orally with HCH at 25 and 100mg/kg b.w. for 2 weeks. Lipid peroxidation and glutathione depletion was seen in all the brain regions of HCH treated rats. The brain regions showed distinct variation in the antioxidant enzyme activities. Activities of glutathione peroxidase, glutathione reductase, glutathione-S-transferase and catalase were markedly induced whereas superoxide dismutase was inhibited at higher dose in all the brain regions. Marked induction and inhibition of the antioxidant enzymes, especially in the cortex and to varying degrees in other brain regions, was seen in HCH treated rats. These biochemical changes suggest vulnerability to oxidative stress in the brain is region-specific. Whether these changes are adaptive or compromise the capacity of the brain to deal with the HCH-induced oxidative stress that could lead to degenerative neurotoxic manifestations remain to be understood.

Metallothionein provides zinc-mediated protective effects against methamphetamine toxicity in SK-N-SH cells

Methamphetamine (METH) is a drug of abuse and neurotoxin that induces Parkinson's-like pathology after chronic usage by targeting dopaminergic neurons. Elucidation of the intracellular mechanisms that underlie METH-induced dopaminergic neuron toxicity may help in understanding the mechanism by which neurons die in Parkinson's disease. In the present study, we examined the role of reactive oxygen species (ROS) in the METH-induced death of human dopaminergic SK-N-SH cells and further assessed the neuroprotective effects of zinc and metallothionein (MT) against METH-induced toxicity in culture. METH significantly increased the production of reactive oxygen species, decreased intracellular ATP levels and reduced the cell viability. Pre-treatment with zinc markedly prevented the loss of cell viability caused by METH treatment. Zinc pre-treatment mainly increased the expression of metallothionein and prevented the generation of reactive oxygen species and ATP depletion caused by METH. Chelation of zinc by CaEDTA caused a significant decrease in MT expression and loss of protective effects of MT against METH toxicity. These results suggest that zinc-induced MT expression protects dopaminergic neurons via preventing the accumulation of toxic reactive oxygen species and halting the decrease in ATP levels. Furthermore, MT may prevent the loss of mitochondrial functions caused by neurotoxins. In conclusion, our study suggests that MT, a potent scavenger of free radicals is neuroprotective against dopaminergic toxicity in conditions such as drug of abuse and in Parkinson's disease.

Overexpression of glutathione peroxidase protects immature murine neurons from oxidative stress

Neuronal enzyme systems involved in free radical detoxification are developmentally regulated such that intracellular glutathione peroxidase (GPx-1) activity is low in the newborn mouse brain. We hypothesized that neurons expressing a higher level of GPx-1 will be more resistant to hydrogen peroxide (H(2)O(2)) exposure. We show a dose-dependent protection against H(2)O(2) in primary neuronal cultures from fetuses overexpressing human GPx-1 compared to wild types of the same genetic background. Exogenous antioxidants completely protected neurons, even at extremely high H(2)O(2 )concentrations and regardless of the genotype. Specific depletion of glutathione with buthionine sulfoximine increased cell death in transgenic cultures exposed to 200 microM H(2)O(2), reducing protection afforded by increased GPx-1 activity. Increased GPx-1 expression in immature cortical neurons confers protection from oxidative stress, but availability of reducing equivalents determines susceptibility to oxidative cell death.

The effects of stress and aging on glutathione metabolism

Glutathione plays a critical role in many biological processes both directly as a co-factor in enzymatic reactions and indirectly as the major thiol-disulfide redox buffer in mammalian cells. Glutathione also provides a critical defense system for the protection of cells from many forms of stress. However, mild stress generally increases glutathione levels, often but not exclusively through effects on glutamate cysteine ligase, the rate-limiting enzyme for glutathione biosynthesis. This upregulation in glutathione provides protection from more severe stress and may be a critical feature of preconditioning and tolerance. In contrast, during aging, glutathione levels appear to decline in a number of tissues, thereby putting cells at increased risk of succumbing to stress. The evidence for such a decline is strongest in the brain where glutathione loss is implicated in both Parkinson's disease and in neuronal injury following stroke.

Oxidative stress in the hippocampus after pilocarpine-induced status epilepticus in Wistar rats

The role of oxidative stress in pilocarpine-induced status epilepticus was investigated by measuring lipid peroxidation level, nitrite content, GSH concentration, and superoxide dismutase and catalase activities in the hippocampus of Wistar rats. The control group was subcutaneously injected with 0.9% saline. The experimental group received pilocarpine (400 mg.kg(-1), subcutaneous). Both groups were killed 24 h after treatment. After the induction of status epilepticus, there were significant increases (77% and 51%, respectively) in lipid peroxidation and nitrite concentration, but a 55% decrease in GSH content. Catalase activity was augmented 88%, but superoxide dismutase activity remained unaltered. These results show evidence of neuronal damage in the hippocampus due to a decrease in GSH concentration and an increase in lipid peroxidation and nitrite content. GSH and catalase activity are involved in mechanisms responsible for eliminating oxygen free radicals during the establishment of status epilepticus in the hippocampus. In contrast, no correlations between superoxide dismutase and catalase activities were observed. Our results suggest that GSH and catalase activity play an antioxidant role in the hippocampus during status epilepticus.

Expression pattern of cytosolic glutathione peroxidase (cGPx) mRNA during mouse embryogenesis

The selenoprotein cytosolic glutathione peroxidase (cGPx) is ubiquitously distributed in a variety of organs, and its primary function is to protect oxidative damage. To investigate the spatial and temporal expression pattern of cGPx mRNA in embryogenesis, as this has not been studied before, reverse transcription-polymerase chain reaction (RT-PCR) was carried out in a thermal cycler using mouse-specific cGPx primers, and in situ hybridization was performed in whole embryos or embryonic tissues using digoxigenin-labeled mouse cGPx riboprobes. Expression of cGPx mRNA was detected in all the embryos retrieved from embryonic days (EDs) 7.5 to 18.5. On EDs 10.5-12.5, cGPx mRNA was highly expressed in the margin of forelimb and hindlimb buds and dorsally in the cranial neural tube, including the telencephalon, diencephalon, and hindbrain neural tube. On ED 13.5, cGPx mRNA was accumulated especially in vibrissae, forelimb and hindlimb plates, tail, and spinal cord. On EDs 14.5-16.5, cGPx mRNA was found in the developing brain, Rathke's pouch, thymus, lung, and liver. On ED 17.5, the expression of cGPx mRNA was apparent in various tissues such as brain, submandibular gland, vibrissae, heart, lung, liver, stomach, intestine, pancreas, skin, and kidney. In particular, cGPx mRNA was greatly expressed in epithelial linings and metabolically active sites such as whisker follicles, alveolar epithelium of lung, surface epithelium and glandular region of stomach, skin epithelium, and cortex and tubules of kidney. Overall results indicate that cGPx mRNA is expressed in developing embryos, cell-specifically and tissue-specifically, suggesting that cGPx may function to protect the embryo against reactive oxygen species and/or hydroperoxides massively produced by the intracellular or extracellular environment.

Effects of steroid hormones on catalase activity in neuronal and glial cell systems

The aim of the present study was to determine short- (1 and 3 h) and long-term (24 h) effects of glucocorticoids [GCs; corticosterone (CORT), dexamethasone (DEX) and 6-methylprednisolone (6-MP)] and gonadal steroids [GSs; 17beta-estradiol (E2), progesterone (PROG) and testosterone (TEST)] on the activity of the hydrogen-peroxide-detoxifying enzyme catalase (CAT) in neural hippocampal HT22 cells and glial C6 cells because such effects have been described in peripheral organ systems. In HT22 cells, only long-term treatment with glucocorticoids (10(-5) M) induced effects on catalase activity, whereas gonadal steroids (10(-5) M) affected catalase activity after both short- and long-term incubations. At a lower concentration of 10(-7) M, glucocorticoids exerted only short-term treatment effects on catalase activity, while gonadal steroids (10(-7) M) affected the enzyme activity after short- and long-term treatments. In C6 glial cells, both glucocorticoids (10(-7) M) and gonadal steroids (10(-7) M) induced short- and long-term treatment effects. Thereby, our data show that steroid hormones differentially regulate catalase activity in models of the central nervous system (CNS) in a time- and steroid-dependent manner.

Update on olfactory mucosal metabolic enzymes: age-related changes and N-acetyltransferase activities

We have expanded previous observations on olfactory metabolic enzymes by examining the content of various metabolic enzymes in the olfactory mucosa of the male Long-Evans rat at different ages. Age-related changes in metabolic enzyme content may be related to changes in susceptibility to toxicants with age and may also contribute to altered odorant perception in the elderly. While some enzymes did not vary over the age range examined, decreases in the microsomal content of other enzymes were observed. While mRNA for acetyltransferase enzymes has previously been described in olfactory mucosa, the markedly higher activity of olfactory acetyltransferases compared to liver had not previously been described. Acetyltransferases are important in the metabolism of drugs and toxicants that are aromatic amine derivatives and may contribute to the bioactivation of rodent olfactory mucosal carcinogens such as 2,6-dimethylaniline and alachlor. These studies show that the olfactory mucosa varies in its metabolic capacity with age, and characterize another class of metabolic enzymes in the olfactory mucosa, both of which may impact significantly on responses to toxicants and therapeutic agents in the nasal cavity.

Aging-related increase in oxidative stress correlates with developmental pattern of beta-secretase activity and beta-amyloid plaque formation in transgenic Tg2576 mice with Alzheimer-like pathology

The molecular mechanisms of beta-amyloidogenesis in sporadic Alzheimer's disease are still poorly understood. To reveal whether aging-associated increases in brain oxidative stress and inflammation may trigger onset or progression of beta-amyloid deposition, a transgenic mouse (Tg2576) that express the Swedish double mutation of human amyloid precursor protein (APP) was used as animal model to study the developmental pattern of markers of oxidative stress and APP processing. In Tg2576 mouse brain, cortical levels of soluble beta-amyloid (1-40) and (1-42) steadily increased with age, but significant deposition of fibrillary beta-amyloid in cortical areas did not occur before postnatal age of 10 months. The slope of increase in cerebral cortical beta-secretase (BACE1) activities in Tg2576 mice between ages of 9 and 13 months was significantly higher as compared to that of the alpha-secretase, while the expression level of BACE1 protein and mRNA did not change with age. The activities of superoxide dismutase and glutathione peroxidase in cortical tissue from Tg2576 mice steadily increased from postnatal age 9-12 months. The levels of cortical nitric oxide, and reactive nitrogen species demonstrated peak values around 9 months of age, while the level of interleukin-1beta steadily increased from postnatal month 13 onwards. The developmental temporal coincidence of increased levels of reactive nitrogen species and antioxidative enzymes with the onset of beta-amyloid plaque deposition provides further evidence that developmentally and aging-induced alterations in brain oxidative status exhibit a major factor in triggering enhanced production and deposition of beta-amyloid, and potentially predispose to Alzheimer's disease.

Reactive oxygen species and synaptic plasticity in the aging hippocampus

Aging is associated with a general decline in physiological functions including cognitive functions. Given that the hippocampus is known to be critical for certain forms of learning and memory, it is not surprising that a number of neuronal processes in this brain area appear to be particularly vulnerable to the aging process. Long-term potentiation (LTP), a form of synaptic plasticity that has been proposed as a biological substrate for learning and memory, has been used to examine age-related changes in hippocampal synaptic plasticity. A current hypothesis states that oxidative stress contributes to age-related impairment in learning and memory. This is supported by a correlation between age, memory impairment, and the accumulation of oxidative damage to cellular macromolecules. However, it also has been demonstrated that ROS are necessary components of signal transduction cascades during normal physiological processes. This review discusses the evidence supporting the dual role of reactive oxygen species (ROS) as cellular messenger molecules in normal LTP, as well their role as damaging toxic molecules in the age-related impairment of LTP. In addition, we will discuss parallel analyses of LTP and behavioral tests in mice that overexpress antioxidant enzymes and how the role of antioxidant enzymes and ROS in modulating these processes may vary over the lifespan of an animal.

Met-enkephalin modulates resistance to oxidative stress in mouse brain

The purpose of this study was to investigate the effect of opioide peptide Met-enkephalin (MENK) on resistance to oxidative stress in the brain of 4, 10 and 18 months old CBA mice of both sexes. This was done by determination of oxidant status via lipid peroxidation (LPO) and antioxidant status by determination of total superoxide dismutase (tSOD), catalase (CAT) and glutathione peroxidase (Gpx). Results showed that brain of adult male mice is less resistant to oxidative stress than brain of adult females. The difference is mainly due to higher CAT activity and lower LPO activity in female brain. MENK decreased resistance to stress in the brain of both sexes but the effect appeared earlier in males (10 months of age) than in females (18 months of age). Also, MENK could pronounce its effect on resistance to oxidative stress in a gender-related manner: in female mice via regulation of antioxidant enzyme activities and in male mice via regulation of oxidant processes respectively.

Free radicals: key to brain aging and heme oxygenase as a cellular response to oxidative stress

Aging is one of the unique features in all organisms. The impaired functional capacity of many systems characterizes aging. When such impairments occur in the brain, the susceptibility to neurodegenerative diseases amplifies considerably. The free radical theory of aging posits that the functional impairments in brains are due to the attack on critical cellular components by free radicals, reactive oxygen species, and reactive nitrogen species produced during normal metabolism. In this review, we examine this concept based on the parameters of oxidative stress in correlation to aging. The parameters for lipid peroxidation are phospholipid composition, reactive aldehydes, and isoprostanes. The parameters for protein oxidation are protein carbonyl levels, protein 3-nitrotyrosine levels, electron paramagnetic resonance, and oxidative stress-sensitive enzyme activities. We conclude that free radicals are, at least partially, responsible for the functional impairment in aged brains. The aging brain, under oxidative stress, responds by induction of various protective genes, among which is heme oxygenase. The products of the reaction catalyzed by heme oxygenase, carbon monoxide, iron, and biliverdin (later to bilirubin) each have profound effects on neurons. Although there may be other factors contributing to brain aging, free radicals are involved in the damaging processes associated with brain aging, and cellular stress response genes are induced under free radical oxidative stress. Therefore, this review supports the proposition that free radicals are, indeed, a key to brain aging.

Free radicals and brain aging

We reviewed here the formation of free radicals and its effect physiologically. Studies mentioned above have indicated that free radical/ROS/RNS involvement in brain aging is direct as well as correlative. Increasing evidence demonstrates that accumulation of oxidation of DNA, proteins, and lipids by free radicals are responsible for the functional decline in aged brains. Also, lipid peroxidation products, such as MDA, HNE, and acrolein, were reported to react with DNA and proteins to produce further damage in aged brains. Therefore, the impact of free radicals on brain aging is pronounced. It has been estimated that 10,000 oxidative interactions occur between DNA and endogenously generated free radicals per human cell per day, and at least one of every three proteins in the cell of older animals is dysfunctional as an enzyme or structural protein, due to oxidative modification. Although these estimated numbers reveal that free radical-mediated protein and DNA modification play significant roles in the deterioration of aging brain, they do not imply that free radical damages are the only cause of functional decline in aged brain. Nevertheless,although other factors may be involved in the cascade of damaging effects in the brain, the key role of free radicals in this process cannot be underestimated. This article has examined the role and formation of free radicals in brain aging. We propose that free radicals are critical to cell damage in aged brain and endogenous, and that exogenous antioxidants, therefore, may play effective roles in therapeutic strategies for age-related neurodegenerative disorders.

Alpha lipoic acid for dementia

BACKGROUND

Oxidative processes have been implicated in the pathogenesis of neurodegenerative dementias including Alzheimer's disease. Protecting the central nervous system against these damaging mechanisms may be a useful therapeutic approach. Alpha lipoic acid (ALA) is an endogenous antioxidant that interrupts cellular oxidative processes in both its oxidized and reduced forms. These properties might qualify ALA for a modulatory role in the treatment of people with dementia.

OBJECTIVES

To assess the role and clinical efficacy of alpha lipoic acid in the treatment of dementia.

SEARCH STRATEGY

A search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG) on 3 February 2003 using the terms 'alpha lipoic acid' and 'thioctic'. The CDCIG Specialized register is updated regularly and contains records from all major health care databases (MEDLINE, EMBASE, PsycInfo, CINAHL) as well as from many trials databases.

SELECTION CRITERIA

All double-blind randomized placebo-controlled trials examining the efficacy of alpha lipoic acid in dementia

DATA COLLECTION AND ANALYSIS

No trials were found that met the selection criteria

MAIN RESULTS

No meta-analysis could be performed. A systematic search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, as well as registers of ongoing and unpublished trials could not identify any studies investigating the use of ALA for dementia.

REVIEWER'S CONCLUSIONS

In the absence of randomized double-blind placebo-controlled trials investigating ALA for dementia, no evidence exists to explore any potential effects. Until data from trials become available for analysis, ALA cannot be recommended for people with dementia.

Induction of oxidative stress by L-2-hydroxyglutaric acid in rat brain

L-2-hydroxyglutaric acid (LGA) is the biochemical hallmark of L-2-hydroxyglutaric aciduria (L-OHGA), an inherited neurometabolic disorder characterized by progressive neurodegeneration with cerebellar and pyramidal signs, mental deterioration, epilepsy, and subcortical leukoencephalopathy. Because the underlying mechanisms of the neuropathology of this disorder are virtually unknown, in this study we tested the in vitro effect of LGA on various parameters of oxidative stress, namely, chemiluminescence, thiobarbituric acid-reactive substances (TBA-RS), protein carbonyl formation (PCF), total radical-trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR), and the activities of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in cerebellum and cerebral cortex of 30-day-old rats. LGA significantly increased chemiluminescence, TBA-RS, and PCF measurements and markedly decreased TAR values in cerebellum, in contrast to TRAP and the activity of the antioxidant enzymes, which were not altered by the acid. Similar but less pronounced effects were provoked by LGA in cerebral cortex. Moreover, the LGA-induced increase of TBA-RS was significantly attenuated by melatonin (N-acetyl-5-methoxytryptamine) and by the combinations of ascorbic acid plus Trolox (soluble alpha-tocopherol) and of superoxide dismutase plus catalase but not by the inhibitor of nitric oxide synthase Nomega-nitro-L-arginine methyl ester (L-NAME), creatine, or superoxide dismutase or catalase alone in either cerebral structure. The data indicate that LGA provokes oxidation of lipids and proteins and reduces the brain capacity to modulate efficiently the damage associated with an enhanced production of free radicals, possibly by inducing generation of superoxide and hydroxyl radicals, which are trapped by the scavengers used. Thus, in case these findings can be extrapolated to human L-OHGA, it may be presumed that oxidative stress is involved in the pathophysiology of the brain damage observed in this disorder.

Modulation of age-related biochemical changes and oxidative stress by vitamin C and glutathione supplementation in old rats

The present study sought to determine whether supplementation of dietary antioxidant ascorbic acid with glutathione (GSH) could ameliorate the age-related increased oxidative stress and changes in hormonal, lipid and copper (Cu) as well as zinc (Zn) levels in 18-month-old rats. The present study demonstrated that supplementation of vitamin C (30 mg) + GSH 100 mg/kg b.w. significantly reduced the concentration of thiobarbituric acid-reactive substances in liver and testes in old male rats as compared with nonsupplemented ones, indicating lower oxidative stress. In addition, testicular GSH was increased but not hepatic GSH. Also, cholesterol and triglycerides were decreased in the serum of supplemented rats. Furthermore, she serum testosterone level was increased in the same supplemented rats. However, the present results show that the thyroid hormones, T3 and T4, were not influenced. Lastly, the concentration of Cu in serum, liver, brain and testes was increased in supplemented old rats. Zn concentration was also increased in the same organs but not in the liver. According to the present study, the supplementation of antioxidants could play an important role in the modulation of the oxidative damage and changes associated with age.

Regional rat brain distribution of heme oxygenase-1 and manganese superoxide dismutase mRNA: relevance of redox homeostasis in the aging processes

Increasing evidence supports the notion that reduction of cellular expression and activity of antioxidant proteins and the resulting increase of oxidative stress are fundamental causes in the aging processes and neurodegenerative diseases. In the present study, we evaluated, in the brains of young and aged rats, the gene expression profiles of two inducible proteins critically involved in the cellular defense against endogenous or exogenous oxidants: heme oxygenase-1 (HO-1) and manganese superoxide dismutase-2 (SOD-2). SOD-2 is an essential antioxidant and HO-1 has been reported to be very active in regulating cellular redox homeostasis. Deregulation of these enzymes has been extensively reported to play a crucial role in the pathogenesis of neurodegenerative disorders. To measure the regional distribution of HO-1 and SOD-2 transcript levels in the rat brain, we have developed a real time quantitative reverse transcription-polymerase chain reaction protocol. Although these two genes presented a highly dissimilar range of expression, with SOD-2 >HO-1, both transcripts were highly expressed in the cerebellum and the hippocampus, showing in a different scale a strikingly parallel distribution gradient. To further investigate the regional brain expression of these mRNAs, we performed in situ hybridization using specific riboprobes. In situ hybridization results showed that both transcripts were highly concentrated in the hippocampus, the cerebellum and some specific regions of the brain cortex. We have also quantified, by reverse transcription-polymerase chain reaction, the brain expression of HO-1 and SOD-2 mRNAs in middle aged (12 months) and aged (28 months) rats. We found that the hippocampus of aged rats presents a significant down regulation of SOD2 mRNA expression and a parallel upregulation of HO-1 mRNA compared with young (6 months) and middle-aged rats. Furthermore, in the cerebellum of the aged rats, we detected a parallel significant upregulation of both HO-1 and SOD-2 transcripts. These regional age-dependent differences may help to explain the increased susceptibility to oxidative damage in these two brain areas during aging.

Ceruloplasmin regulates iron levels in the CNS and prevents free radical injury

Ceruloplasmin is a ferroxidase that oxidizes toxic ferrous iron to its nontoxic ferric form. We have previously reported that a glycosylphosphatidylinositol-anchored form of ceruloplasmin is expressed in the mammalian CNS. To better understand the role of ceruloplasmin in iron homeostasis in the CNS, we generated a ceruloplasmin gene-deficient (Cp(-/-)) mouse. Adult Cp(-/-) mice showed increased iron deposition in several regions of the CNS such as the cerebellum and brainstem. Increased lipid peroxidation was also seen in some CNS regions. Cerebellar cells from neonatal Cp(-/-) mice were also more susceptible to oxidative stress in vitro. Cp(-/-) mice showed deficits in motor coordination that were associated with a loss of brainstem dopaminergic neurons. These results indicate that ceruloplasmin plays an important role in maintaining iron homeostasis in the CNS and in protecting the CNS from iron-mediated free radical injury. Therefore, the antioxidant effects of ceruloplasmin could have important implications for various neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease in which iron deposition is known to occur.

Glutathione, iron and Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease involving neurodegeneration of dopaminergic neurons of the substantia nigra (SN), a part of the midbrain. Oxidative stress has been implicated to play a major role in the neuronal cell death associated with PD. Importantly, there is a drastic depletion in cytoplasmic levels of the thiol tripeptide glutathione within the SN of PD patients. Glutathione (GSH) exhibits several functions in the brain chiefly acting as an antioxidant and a redox regulator. GSH depletion has been shown to affect mitochondrial function probably via selective inhibition of mitochondrial complex I activity. An important biochemical feature of neurodegeneration during PD is the presence of abnormal protein aggregates present as intracytoplasmic inclusions called Lewy bodies. Oxidative damage via GSH depletion might also accelerate the build-up of defective proteins leading to cell death of SN dopaminergic neurons by impairing the ubiquitin-proteasome pathway of protein degradation. Replenishment of normal glutathione levels within the brain may hold an important key to therapeutics for PD. Several reports have suggested that iron accumulation in the SN patients might also contribute to oxidative stress during PD.

Age-associated alteration of lipid peroxidation and superoxide dismutase activity in CBA and AKR mice

Oxidative modification of lipids, proteins and DNA by reactive oxygen species in the organism and imbalance between the concentrations of free radicals and the antioxidant defenses may be related to processes such as aging and diseases (cardiovascular, neurodegenerative, cancer, etc.). Although the relationship between oxidant status and antioxidant defence in aging of different species, organs or sexes has been investigated extensively, the studies have produced conflicting results. In order to determine the extent of age-associated alteration, oxidant production and antioxidant status were measured in tissues of CBA and AKR mice of both sexes. At the same time we will focus on lipid peroxidation (LPO) process and superoxide dismutase activity (SOD) of AKR mice related to ontogeny of thymic lymphoma in mice of different age and sex. Male and female CBA and AKR mice aged 3, 6, 12 or 18 months were used. Lipid-bound sialic acid (LSA) content was determined as a malignancy marker. LPO processes of CBA and AKR mice were monitored according to the presence of thiobarbituric acid reactive substances (TBARS) in liver and thymus, and antioxidant status as SOD activity in whole blood. TBARS concentration increased significantly with age in the liver of CBA and AKR mice of both sexes, but only in male thymuses of both strains. TBARS concentration in female thymuses of both strains was unchanged during aging. Thus, age-associated LPO processes of tumor-free mice of both strains were tissue-dependent. In the liver of tumor-bearing CBA and AKR mice as well as in thymuses of AKR mice, TBARS concentration significantly decreased and was neither sex nor tissue related. SOD activity was strain-dependent but independent of sex. However, SOD activity in mice with developed thymomas was drastically reduced in comparison to tumor-free mice. Our data indicate that age associated LPO processes in both strains are only tissue-dependent and SOD activity mainly strain-dependent in tumor-free mice. In tumor-bearing mice LPO processes and SOD activity were not tissue, sex or strain dependent.

Biochemical markers related to Alzheimer's dementia in serum and cerebrospinal fluid

The diagnosis of Alzheimer's disease (AD) is currently based on clinical and neuropsychological examination. To date there is no blood test available that can discriminate dementia patients from healthy individuals. In the present paper, an overview of the current state of knowledge on biologic markers in serum (plasma) and CSF is presented. The combination of characteristic plaque markers tau and amyloid bèta may constitute a specific and sensitive CSF marker for AD. Glial fibrillary acidic protein and antibodies in CSF may be a marker for severe neurodegeneration. CSF concentrations of the oxidative stress markers 3-nitrotyrosine, 8-hydroxy-2'-deoxyguanosine and isoprostanes are increased in AD patients. Serum 24S-OH-cholesterol may be an early whereas glial fibrillary acidic protein autoantibody level may be a late marker for neurodegeneration. To date, serum alpha(1)-Antichymotripsin concentration is the most convincing marker for CNS inflammation. Increased serum homocysteine concentrations have also been consistently reported in AD. In summary, a large overlap in mean concentrations has been observed in studies comparing AD patients with healthy controls for single markers. These studies together support the theory of testing several serum markers in combination for the diagnosis of AD.

Aging- and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo

This is a comprehensive study of the changes in major antioxidant enzymes and antioxidant molecules during intrinsic aging and photoaging processes in the epidermis and dermis of human skin in vivo. We show that the activities of superoxide dismutase and glutathione peroxidase are not changed during these processes in human skin in vivo. Interestingly, the activity of catalase was significantly increased in the epidermis of photoaged (163%) and naturally aged (118%) skin (n = 9), but it was significantly lower in the dermis of photoaged (67% of the young skin level) and naturally aged (55%) skin compared with young (n = 7) skin. The activity of glutathione reductase was significantly higher (121%) in naturally aged epidermis. The concentration of alpha-tocopherol was significantly lower in the epidermis of photoaged (56% of young skin level) and aged (61%) skin, but this was not found to be the case in the dermis. Ascorbic acid levels were lower in both epidermis (69% and 61%) and dermis (63% and 70%) of photoaged and naturally aged skin, respectively. Gluta thione concentrations were also lower. Uric acid did not show any significant changes. Our results suggest that the components of the antioxidant defense system in human skin are probably regulated in a complex manner during the intrinsic aging and photoaging processes.

Increased infarct size and exacerbated apoptosis in the glutathione peroxidase-1 (Gpx-1) knockout mouse brain in response to ischemia/reperfusion injury

Glutathione peroxidase is an antioxidant enzyme that is involved in the control of cellular oxidative state. Recently, unregulated oxidative state has been implicated as detrimental to neural cell viability and involved in both acute and chronic neurodegeneration. In this study we have addressed the importance of a functional glutathione peroxidase in a mouse ischemia/reperfusion model. Two hours of focal cerebral ischemia followed by 24 h of reperfusion was induced via the intraluminal suture method. Infarct volume was increased three-fold in the glutathione peroxidase-1 (Gpx-1) -/- mouse compared with the wild-type mouse; this was mirrored by an increase in the level of apoptosis found at 24 h in the Gpx-1 -/- mouse compared with the wild-type mouse. Neuronal deficit scores correlated to the histologic data. We also found that activated caspase-3 expression is present at an earlier time point in the Gpx-1 -/- mice when compared with the wild-type mice, which suggests an enhanced susceptibility to apoptosis in the Gpx-1 -/- mouse. This is the first known report of such a dramatic increase, both temporally and in level of apoptosis in a mouse stroke model. Our results suggest that Gpx-1 plays an important regulatory role in the protection of neural cells in response to the extreme oxidative stress that is released during ischemia/reperfusion injury.

Lipid peroxidation and antioxidant enzyme activity in different organs of mice exposed to low level of mercury

The effects of mercuric chloride (Hg) on lipid peroxidation (LPO), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione (GSH) levels in different organs of mice (CD-1) were evaluated. Mice were exposed (2 days/week) to 0.0 (control), 0.8 (low) and 8.0 (mid) and 80.0 (high) gHg/kg/day for 2 weeks. The high dose group was excluded from the study due to high mortality. LPO levels in kidney, testis and epididymus at low and mid doses; GR and GPx levels in testis at mid dose; SOD levels in brain and testis at both doses, liver and epididymus at mid dose; GSH levels in testis at both doses were significantly increased compared to their controls. However, the GR levels in kidney at both doses and in epididymus at mid dose; GPx levels in kidney and epididymus and SOD levels in kidney at both the doses; GSH levels in epididymus at mid dose were significantly decreased compared to their control. Body weight gain and food efficiency were significantly reduced (p<0.05) in mid dose. These results indicated that Hg treatment enhanced LPO in all tissues, but showed significant enhancement only in kidney, testis and epididymus suggesting that these organs were more susceptible to Hg toxicity. The increase in antioxidant enzyme levels in testis could be a mechanism protecting the cells against reactive oxygen species.

Superoxide dismutase, glutathione peroxidase activities and the hydroperoxide concentration are modified in the hippocampus of epileptic rats

The relationship between free radical and scavenger enzymes has been found in the epileptic phenomena and reactive oxygen species have been implicated in seizure-induced neurodegeneration. Using the epilepsy model obtained by systemic administration of pilocarpine (PILO) in rats, we investigated the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities as well as the hydroperoxide (HPx) concentration in the hippocampus of rats during status epilepticus (SE), silent and chronic periods. The enzyme activities as well as the HPx concentration were measured using spectrophotometric methods and the results compared to values obtained from saline-treated animals. The SOD activity decreased after long-lasting SE period and during the chronic phase. In addition, HPx levels increased in same periods whereas the GPx activity increased only in the hippocampus of animals submitted to 1 h of SE. Animals presenting partial seizures, those submitted to 5 h of SE and animals from the silent period (seizure free) showed normal levels of SOD, GPx and HPx. These results show a direct evidence of lipid peroxidation during seizure activity that could be responsible for neuronal damage in the hippocampus of rats, during the establishment of PILO model of epilepsy.

Motor skills and motor learning in Lurcher mutant mice during aging

Motor learning abilities on the rotorod and motor skills (muscular strength, motor coordination, static and dynamic equilibrium) were investigated in three-, nine-, 15- and 21-month-old Lurcher and control mice. Animals were subjected to motor training on the rotorod before being subjected to motor skills tests. The results showed that control mice exhibited decrease of muscular strength and specific equilibrium impairments in static conditions with age, but were still able to learn the motor task on the rotorod even in old age. These results suggest that, in control mice, efficiency of the reactive mechanisms, which are sustained by the lower transcerebellar loop (cerebello-rubro-olivo-cerebellar loop), decreased with age, while the efficiency of the proactive adjustments, which are sustained by the upper transcerebellar loop (cerebello-thalamo-cortico-ponto-cerebellar loop), did not. In spite of their motor deficits, Lurcher mutants were able to learn the motor task at three months, but exhibited severe motor learning deficits as soon as nine months. Such a deficit seems to be associated with dynamic equilibrium impairments, which also appeared at nine months in these mutants. By two months of age, degeneration of the cerebellar cortex and the olivocerebellar pathway in Lurcher mice has disrupted both lower and upper transcerebellar loops. Disruption of the lower loop could well explain precocious static equilibrium deficits. However, in spite of disruption of the upper loop, motor learning and dynamic equilibrium were preserved in young mutant mice, suggesting that either deep cerebellar nuclei and/or other motor structures involved in proactive mechanisms needed to maintain dynamic equilibrium and to learn motor tasks, such as the striatopallidal system, are sufficient. The fact that, in Lurcher mutant mice, motor learning decreased by the age of nine months suggests that the above-mentioned structures are less efficient, likely due to degeneration resulting from precocious and focused neurodegeneration of the cerebellar cortex. From this behavioral approach of motor skills and motor learning during aging in Lurcher mutant mice, we postulated the differential involvement of two transcerebellar systems in equilibrium maintenance and motor learning. Moreover, in these mutants, we showed that motor learning abilities decreased with age, suggesting that the precocious degeneration of the cerebellar Purkinje cells had long-term effects on motor structures which are not primarily affected. Thus, from these results, Lurcher mutant mice therefore appear to be a good model to study the pathological evolution of progressive neurodegeneration in the central nervous system during aging.

Oxidative stress and neuronal DNA fragmentation mediate age-dependent vulnerability to the mitochondrial toxin, 3-nitropropionic acid, in the mouse striatum

Oxidative stress is involved in the neuropathology of several neurodegenerative diseases and stroke, all of which are related to excitotoxicity. Age-dependent vulnerability is characteristic of these conditions. It is not clear whether apoptosis-related neuronal death is involved in age-dependent vulnerability to excitotoxicity. We evaluated whether apoptosis-related neuronal death after treatment with 3-nitropropionic acid (3-NP) is age-dependent in the mouse striatum. We have demonstrated that oxidative stress occurs early after 3-NP treatment and even more so in aged mice. DNA fragmentation with terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling staining and gel electrophoresis occurred in an age-dependent fashion. Expression of the DNA repair enzyme, apurinic/apyrimidinic endonuclease, was more attenuated in old mice. Therefore, these results suggest that oxidative stress induces age-dependent neuronal apoptosis in the mouse striatum after 3-NP treatment, which in turn produces an age-dependent vulnerability to 3-NP.