Demential syndromes and the lipid metabolism

Relevance of the glutathione system in temporal lobe epilepsy: evidence in human and experimental models

Oxidative stress, which is a state of imbalance in the production of reactive oxygen species and nitrogen, is induced by a wide variety of factors. This biochemical state is associated with diseases that are systemic as well as diseases that affect the central nervous system. Epilepsy is a chronic neurological disorder, and temporal lobe epilepsy represents an estimated 40% of all epilepsy cases. Currently, evidence from human and experimental models supports the involvement of oxidative stress during seizures and in the epileptogenesis process. Hence, the aim of this review was to provide information that facilitates the processing of this evidence and investigate the therapeutic impact of the biochemical status for this specific pathology.

Oxidative stress and mitochondrial dysfunction across broad-ranging pathologies: toward mitochondria-targeted clinical strategies

Beyond the disorders recognized as mitochondrial diseases, abnormalities in function and/or ultrastructure of mitochondria have been reported in several unrelated pathologies. These encompass ageing, malformations, and a number of genetic or acquired diseases, as diabetes and cardiologic, haematologic, organ-specific (e.g., eye or liver), neurologic and psychiatric, autoimmune, and dermatologic disorders. The mechanistic grounds for mitochondrial dysfunction (MDF) along with the occurrence of oxidative stress (OS) have been investigated within the pathogenesis of individual disorders or in groups of interrelated disorders. We attempt to review broad-ranging pathologies that involve mitochondrial-specific deficiencies or rely on cytosol-derived prooxidant states or on autoimmune-induced mitochondrial damage. The established knowledge in these subjects warrants studies aimed at elucidating several open questions that are highlighted in the present review. The relevance of OS and MDF in different pathologies may establish the grounds for chemoprevention trials aimed at compensating OS/MDF by means of antioxidants and mitochondrial nutrients.

Fragmentation of a linoleate-derived γ-hydroperoxy-α,β-unsaturated epoxide to γ-hydroxy- and γ-oxo-alkenals involves a unique pseudo-symmetrical diepoxycarbinyl radical

Many of the pathological effects of lipid peroxidation are mediated by aldehydes generated through fragmentation of lipid peroxides. Among these aldehydes, the γ-hydroxy- and γ-oxo-α,β-alkenals, e.g., 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE), are especially prone to modifying proteins and DNA through covalent adduction. In addition the "mirror image" γ-hydroxy- and γ-oxo-α,β-alkenal phospholipids can serve as high-affinity ligands for biological receptors triggering pathology. Therefore, the mechanisms by which these aldehydes are generated in vivo are under intense scrutiny. We now report observations supporting the intermediacy of a unique pseudo-symmetrical diepoxycarbinyl radical that accounts for the coproduction of HNE, ONE, and their mirror image analogues 9-hydroxy-12-oxo-10(E)-dodecenoic acid and 9-keto-12-oxo-10-dodecenoic acid upon fragmentation of 13-hydroperoxy-cis-9,10-epoxyoctadeca-11-enoic acid.

Use of liquid chromatography with electrochemical detection for the determination of antioxidants in less common fruits

Neurodegenerative disorders (NDD) have become the common global health burden over the last several decades. According to World Health Organization (WHO), a staggering 30 million people will be affected by Alzheimer's disease in Europe and the USA by 2050. Effective therapies in this complex field considering the multitude of symptoms associated with NDD indications, have not been found yet. Based on the results of NDD related studies, prevention appears to be the promise alternative. Antioxidative and anti-inflammatory properties are hypothesized for natural phenolics, a group of plant secondary products that may positively impact neurodegenerative diseases. In these studies, phenolic-rich extracts from less common fruit species: Blue honeysuckle (Lonicera edulis, Turcz. ex. Freyn), Saskatoon berry (Amelanchier alnifolia Nutt.), and Chinese hawthorn (Crateagus pinnatifida Bunge) were obtained and analyzed to detect neuroprotective substances content and establish a potential therapeutic value. High performance liquid chromatography with electrochemical detection was optimized and further applied on analysis of the extracts of less common fruit species. It was observed that Chinese hawthorn and Blue honeysuckle extracts are potent source of neuroprotective phenolic antioxidants. In accordance the results, it appears that the fruit or formulated products may have the potential for the prevention of neurodegenerative diseases.

Hypericum perforatum extract demonstrates antioxidant properties against elevated rat brain oxidative status induced by amnestic dose of scopolamine

This study was designed to investigate if the impairment of learning and memory induced by acute administration of scopolamine (1.4 mg/kg ip) in rats is associated with altered brain oxidative stress status. The passive avoidance paradigm was used to assess retrieval memory of rats after scopolamine treatment. Following retrieval testing, biochemical assessments of malondialdehyde (MDA), glutathione peroxidase (GSHPx), glutathione (GSH), and superoxide dismutase (SOD) levels/activities as oxidative stress indices were performed. This study also investigated the effect of acute administration of Hypericum perforatum extract (4.0, 8.0, 12.0, and 25.0 mg/kg ip), containing flavonoids with documented antioxidant activity, on brain oxidative status of nai;ve rats treated with amnestic dose of scopolamine. Results showed that administration of 1.4 mg/kg of scopolamine impaired retrieval memory of rats and that such amnesia was associated with elevated MDA and reduced GSH brain levels. In nai;ve rats, which have not been exposed to conditioned fear, scopolamine administration also increased MDA and reduced GSH levels, although with an increase in brain GSHPx activity. Pretreatment of the animals with Hypericum extract (4, 8, and 12 mg/kg) resulted in an antioxidant effect through altering brain MDA, GSHPx, and/or GSH level/activity. Since oxidative stress is implicated in the pathophysiology of dementia, the findings of this study may substantiate the value of scopolamine-induced amnesia in rats as a valid animal model to screen for drugs with potential therapeutic benefit in dementia. Exposure of animals to conditioned fear may be suggested to impair the balance between the rate of lipid peroxidation and the activation of GSHPx as a compensatory antioxidant protective mechanism. It is also concluded that low doses of Hypericum extract, demonstrating antioxidant activity, may be of value for demented patients exhibiting elevated brain oxidative status. Since depression commonly coexists with dementia, Hypericum extract as a drug with documented antidepressant action may also be a better alternative than several other antidepressant medications that have not been evaluated to test their effect on brain oxidative status during amnesia.

Isolevuglandin-protein adducts in humans: products of free radical-induced lipid oxidation through the isoprostane pathway

A family of extremely reactive electrophiles, isolevuglandins (isoLGs), is generated in vivo by free radical-induced lipid oxidation and rearrangement of endoperoxide intermediates of the isoprostane pathway. Protein adducts of two different oxidized lipids, isoLGE(2) and iso[4]LGE(2), and the corresponding autoantibodies are present in human blood. Western blot analysis of a polyacrylamide gel electrophoresis gel detects several immunoreactive plasma proteins. Only a minor fraction of the isoLG-protein modifications is associated with low density lipoprotein since mean levels were decreased only 20-22% by immunoprecipitation of apolipoprotein B (apoB). Mean levels of both isoLGE(2) and iso[4]LGE(2)-protein adducts in plasma from patients with atherosclerosis (AS) (n=16) or end-stage renal disease (RD) (n=8) are about twice those in healthy individuals (n=25). These elevated levels are not related to variations in age, total cholesterol or apoB. A linear correlation (r=0.79) between plasma isoLGE(2) and iso[4]LGE(2)-protein adduct levels in all 49 individuals is consistent with a common free radical-induced mechanism for the production of both oxidized lipids in vivo. The correlation is even stronger (r=0.86) for patients with AS or RD. That isoLG-protein adduct levels are more strongly correlated with disease than are total cholesterol or apoB suggests an independent defect that results in an abnormally high level of oxidative injury associated with AS and RD.

Oxidative-stress associated parameters (lactoferrin, superoxide dismutases) in serum of patients with Alzheimer's disease

In this case/control study, serum levels of oxidative stress related parameters such as Fe-binding lactoferrin (LTF), Mn- and Zn,Cu-superoxide dismutase (SOD) were determined by enzyme linked immunoassays in patients suffering from the Alzheimer's dementia as well as in non-demented controls. The Mn-SOD concentration was significantly (P<0.05, U-test) reduced in patients suffering from Alzheimer's disease if compared to non-demented controls. The other parameters investigated did not differ significantly between both groups. Our findings give evidence for the hypothesis of a disturbed free radical metabolism in Alzheimer's disease. The specificity of these results remains to be clarified. Further studies are needed to elucidate the relevance of oxidative stress in the etiopathogenesis of the Alzheimer's disease.

Free radical pathology in schizophrenia: a review

There is evidence that free radicals are involved in membrane pathology, and may play a role in schizophrenia. Free radicals are reactive chemical species generated during normal metabolic processes, and, in excess, can damage lipids, proteins, and DNA. Regions of high oxygen consumption, lipid content, and transition metals are at particular risk. Hence, neuronal membranes are uniquely vulnerable to radical-mediated damage. Elaborate antioxidant defense systems exist to protect against oxidative stress. In schizophrenia there is evidence for dysregulation of free radical metabolism, as detected by abnormal activities of critical antioxidant enzymes and other indices of lipid peroxidation in plasma, red blood cells, and cerebrospinal fluid. Such abnormalities have been associated with tardive dyskinesia, negative symptoms, neurological signs, poor premorbid function, and CT scan abnormalities. Studies to date have generally been exploratory. Further elucidation of the role of free radicals and antioxidants in schizophrenia and its treatment will require systematic investigation.

Transgenic glutathione peroxidase mouse models for neuroprotection studies

Seleno-glutathione peroxidase (GSHPx) is considered to be the major enzymatic activity in charge of removing excess cytosolic and mitochondrial H2O2 in most tissues including brain. Intracellular GSHPx activity is therefore hypothesized to be one important factor that contributes to minimize hydroxyl radical formation via Fenton-type reactions. An animal model was developed to challenge this hypothesis in vivo and evaluate the role of GSHPx in hydroperoxide metabolism and oxidative stress homeostasis. Three lines of transgenic mice, homozygous for the integration of 1 to 3 GSHPx transgene copies, have been generated. The transgene was placed under transcriptional control of a metallothionein promoter (hMT-IIA). This promoter was chosen because metallothionein expression, normally low in most tissues, can be induced by several inflammatory cytokines, protein kinase C activators, and stress agents including heavy metals. The data reported here provide information on the constitutive expression of GSHPx mRNA and enzyme in various brain regions of healthy untreated adult tg-MT-GPx mice. Northern and/or Western analysis indicated that transgenic GSHPx was expressed constitutively in all brain regions investigated in tg-MT-GPx-6 mice, including the cerebral cortex, brainstem, hippothalamus, cerebellum, substantia nigra, and striatum. Similar results were obtained with the two other transgenic lines, tg-MT-GPx-11 and -13. Depending on the brain region, the GSHPx immunoreactivity detected in tissue extracts with an immunoaffinity-purified polyclonal antibody was about 2- to 5-fold stronger in transgenic extracts than in their non-tg counterparts (western blots). In contrast, the corresponding increase in GSHPx activity measured in these extracts was smaller, for example, about 1.5-fold in transgenic mesencephalon. Immunocytochemical data indicated that GSHPx-like staining was distinctly more intense in transgenic midbrain brain sections than in corresponding non-tg sections. Interestingly, only a subset of the cells displayed higher density staining that most likely reflects increased amounts of GSHPx protein. This observation suggests that the stained cells, not yet identified, may have larger GSHPx activity increments than the cell-average increments measured in tissue extracts. Current work is in progress to determine whether transgenic GSHPx expression may be induced by inflammatory processes or perturbations of heavy metal metabolism.

The uptake of Na-selenite in rat brain. Localization of new glutathione peroxidases in the rat brain

Polyunsaturated fatty acids (PUFAs) occur in phospholipids of synapses of central nervous system (CNS). PUFAs may thus determine the fluidity of synaptosomal membranes and regulate neuronal transmission. It was therefore tempting to suggest an oxidative system in CNS protecting the membrane function, e.g., glutathione peroxidase (GSH-Px). In order to trace GSH-Px Wistar rats were loaded with 4800 kBq of 75Se sodium selenite. By means of gradient ultracentrifugation, particulate fractions of CNS were isolated and radioactivity as well as selenium dependent GSH-Px were estimated. The following data were obtained: 1. All fractions (myelin, synaptic vesicles, synaptosomes, mitochondria, and microsomes) contained 75Se. 2. After acetone precipitation of GSH-Px activity, fractionation on Sephadex G-150 revealed in all particulate fractions at least two peaks of radioactivity with GSH-Px activity. 3. The two GSH-Px peaks from the Sephadex filtration were freeze dried and applied on a hydrophobic T-gel column and eluted with decreasing molarity of ammonium sulfate from 1.5 to 0.05M. The first Sephadex peak with GSH-Px activity from myelin and the second peak with GSH-Px activity from synaptic vesicles could now be resolved into two different fractions of radioactivity on the T-gel. The remaining Sephadex G-150 peaks could only be resolved into one peak of radioactivity. 4. SDS-polyacrylamide gel electrophoresis of the T-gel peaks from all fractions showed a protein band with a mobility identical with that of human erythrocyte GSH-Px. The T-gel elution of myelin, synaptic vesicles and mitochondria gave rise to nearly pure CNS GSH-Px activity. The data presented support the idea that CNS fractions have membrane bound GSH-Px activity that may function as protecting enzymes towards oxidative stress in the brain.

Superiority of antagonic-stress composition versus nicergoline in gerontopsychiatry

Nicergoline (NE)--a cerebral vasodilator with nicotinic acid esterified in its molecule--and Antagonic-Stress (AS) composition--a neurometabolic nootropic, also containing nicotinic acid but with fast and prolonged release--were evaluated in senile dementia of Alzheimer's type (SDAT), mild to moderate intensity (DSM-IV Options Book, 1991 and ICD-10, 1990 criteria). A double-blind, randomized, comparative, and parallel clinical trial was performed on 62 old people divided into 2 groups and exclusively treated with NE or AS. Psychogeriatric evaluations (Sandoz Clinical Assessment-Geriatric scale, Self-Assessment Scale-Geriatric and their subscales) and psychometric tests (digit symbol of WAIS, Wechsler Memory Scale, and Wechsler Adult Intelligence Scale-WAIS) were made before and after 3 months of treatment. Prolonged and large dose treatments with NE and AS significantly decreased the psychogeriatric scores, diminished the deterioration index, and improved cognitive performances (ANOVA). Therapeutical effects of AS were significantly higher than those of NE (ANCOVA). The better actions of AS in senile dementia and for improving cognitive function and behavior are discussed in connection with its multiple neurometabolic composition, the synergism of components, the antiischemic action of its antioxidants, its anti-free radical complementary action (deceleration of the aging rate, brain and erythrocyte lipofuscinolysis, complex antioxidative and scavenger formula), the multivitamin and multimineral supplementation and, finally, with the superiority of multitherapy vs. monotherapy.

Excitotoxicity and neurological disorders: involvement of membrane phospholipids

Excitatory amino acids and their receptors play an important role in membrane phospholipid metabolism. Persistent stimulation of excitatory amino acid receptors by glutamate may be involved in neurodegenerative diseases and brain and spinal cord trauma. The molecular mechanism of neurodegeneration induced by excitatory amino acids is, however, not known. Excitotoxin-induced calcium entry causes the stimulation of phospholipases and lipases. These enzymes act on neural membrane phospholipids and their stimulation results in accumulation of free fatty acids, diacylglycerols, eicosanoids, and lipid peroxides in neurodegenerative diseases and brain and spinal cord trauma. Other enzymes, such as protein kinase C and calcium-dependent proteases, may also contribute to the neuronal injury. Excitotoxin-induced alterations in membrane phospholipid metabolism in neurodegenerative diseases and neural trauma can be studied in animal and cell culture models. These models can be used to study the molecular mechanisms of the neurodegenerative processes and to screen the efficacy of therapeutic drugs.

Oxidative stress in a clonal cell line of neuronal origin: effects of antioxidant enzyme modulation

The effects of intracellularly generated H2O2 on cell viability, morphology, and biochemical markers of injury have been investigated in a clonal cell line of neuronal origin (140-3, mouse neuroblastoma X rat glioma) as a cell culture model for the role of oxidative stress in the long-term loss of neurons in the brain. The H2O2 was generated from the redox cycling of menadione, or by the oxidation of serotonin catalyzed by monoamine oxidase, to simulate the effect of amine neurotransmitter turnover. Incubation with menadione at concentrations as low as 10 microM for several hours resulted in significant losses of cell viability and altered morphology. Similar effects were evident in the presence of serotonin only after incubation overnight with concentrations > 1 mM. The cytotoxicity of either agent was potentiated by preincubation with specific inhibitors of two enzymes important to cellular antioxidant defenses, 3-amino-1,2,4-triazole for catalase and 1,3-bis(chloromethyl)-1-nitrosourea for glutathione reductase. Activity of another antioxidant enzyme of particular importance to antioxidant defenses in brain, the selenoprotein glutathione peroxidase, was stimulated fourfold by growth of cultures in the presence of sodium selenite as a source of active-site Se for the enzyme. The only effect of the selenite on other functionally coupled antioxidant enzymes was a decrease in activity of superoxide dismutase at concentrations > 200 nM. The selenite substantially protected cells against oxidative stress induced by combinations of menadione, 3-amino-1,2,4-triazole, and 1,3-bis(chloromethyl)-1-nitrosourea, but was only marginally effective with serotonin as a source of oxidative stress. The monoamine oxidase inhibitor pargyline increased cell survival in the presence of serotonin, demonstrating the role of this enzyme in its cytotoxicity. DNA damage (single strand breaks), but not lipid peroxidation, correlated with the cytotoxic effects of menadione.

Down's syndrome, dementia, and superoxide dismutase

Mental handicap includes specific behavioural phenotypes apparently caused by single enzyme errors or deletions, for example, compulsive self-mutilation and hypoxanthine-guanine phosphoribosyl transferase deficiency in the Lesch-Nyham syndrome. In Down's syndrome, the possession of additional genetic material is found to be linked to various physical abnormalities (premature cataract formation and hypothyroidism). These close associations between types of behaviour, illnesses, and known genetic abnormalities offer promising avenues for research. In this article we concentrate on the well known link between Down's syndrome and presenile dementia.

The lysosomal system in neuronal cell death: a review

The lysosomal system has often been considered a prominent morphologic marker of distressed or dying neurons. Lysosomes or their constituent hydrolases have been viewed in different neuropathologic states as either initiators and direct agents of cell death, agents of cellular repair and recompensation, effectors of end-stage cellular dissolution, or autolytic scavengers of cellular debris. Limited data and limitations of methodology often do not allow these potential roles to be discriminated. In all forms of neurodegeneration, it may be presumed that lysosomes ultimately rupture and release various hydrolases that promote cell autolysis during the final stages of cellular disintegration. Beyond this perhaps universal contribution to cell death, the degree to which the lysosomal system may be involved in neurodegenerative states varies considerably. In many conditions, morphologic evidence for activation of the lysosomal system is minimal or undetectable. In other cases, lysosomal activation is evident only when other morphologic signs of cell injury are also present. This level of participation may be viewed as either an attempt by the neuron to compensate for or repair the injury or a late-stage event leading to cell dissolution. The early involvement of the lysosomal system in neurodegeneration occurs most commonly in the form of intraneuronal accumulations of abnormal storage profiles or residual bodies (tertiary lysosomes). Very often the lysosomal involvement can be traced to a primary defect or dysfunction of lysosomal components or to accelerated or abnormal membrane breakdown that leads to the buildup of modified digestion-resistant substrates within lysosomes. Because they are often striking, changes in the lysosomal system are a sensitive morphologic indicator of certain types of metabolic distress; however, whether they reflect a salutary response of a compromised neuron or a mechanism to promote cell death and removal of debris from the brain remains to be established for most conditions. Factors that may influence the lysosomal response during lethal neuronal injury include species differences, stage of neuronal development, duration of injury and pace of cell death. The lysosomal system may be more closely coupled to certain forms of neuronal cell death in lower vertebrate or invertebrate systems than in mammalian systems.

Decreased prostaglandin synthesis in postmortem cerebral cortex from patients with Alzheimer's disease

The syntheses of prostaglandin (PG) F2 alpha, E2 and D2, and thromboxane (TX) B2 from [14C]arachidonic acid were studied in frontal cortex of human control and Alzheimer's disease (AD) brains using the microsomal fractions. Under the assay conditions employed, it was found that the major metabolite of [14C]arachidonic acid was PGE2 accounting for 63% of total prostanoid production; PGF2 alpha accounted for 21.5%, TXB2 for 9%, and PGD2 for 6.5%. When AD samples were compared to control samples, microsomal PG synthesis was significantly decreased, with reduced production of PGE2, PGF2 alpha and PGD2. Such decreases in AD brain seem unrelated to age, sex, postmortem delay and, as far as could be determined, antemortem state. In both control and Alzheimer groups, a history of anti-inflammatory therapy seemed to correlate with increased PG synthesis.

Slowed synthesis of DNA and methionine is a pathogenetic mechanism common to dementia in Down's syndrome, AIDS and Alzheimer's disease?

This is a presentation of the hypothesis of a pathogenetic mechanism common to the dementia seen in Alzheimer's disease (AD), Down's Syndrome (DS) and the acquired immunodeficiency syndrome (AIDS). As there is experimental evidence of defective DNA repair capacity in AD and DS, unrepaired damage to DNA occurs in these diseases and may lead to complete breakdown of cellular function and ultimate cell death. Cobalamin and folate are coordinated in a vulnerable key position in the synthesis of DNA and S-adenosylmethionine (SAM). Cobalamin/folate deficiency, a significant feature in senile dementia of Alzheimer type and in AIDS-related dementia complex, will result in concomitant slowed synthesis of DNA and SAM. The enzyme cystathionine-beta-synthetase (CBS) has been localized to the chromosome band 21q22.3. Owing to gene dosage, CBS activity is increased in trisomy 21. As a consequence, cobalamin/folate metabolism is inhibited, which leads to slowing of DNA and SAM synthesis in DS patients. Amyloidosis is a hallmark of AD and DS brain neuropathology and recent experimental findings support the view that amyloid or amyloid precursors stimulate DNA synthesis, which is in agreement with the hypothesis presented in this paper. In summary, demented patients with cobalamin/folate deficiency, trisomy 21 and human immunodeficiency virus (HIV) infection display a simultaneous downregulation of DNA and SAM synthesis, which may indicate a pathway common to the dementia seen in AD, DS and AIDS.

The role of alterations in free radical metabolism in mediating cognitive impairments in Down's syndrome

Down's syndrome (DS) is a genetic disorder involving an excess of chromosome 21 (trisomy 21) in approximately 96% of the cases and comprises approximately 15% of the population with mental retardation (Heller, 1969). In addition to the constitutional mental deficiencies associated with the syndrome many DS patients develop dementia associated with Alzheimer's disease (AD) in their later years of life (Thase et al., 1984). The genetic locus for Cu,Zn-superoxide dismutase (SOD1), a key enzyme in free radical metabolism, is located on chromosome 21, and the activity level of this enzyme is elevated by approximately 50% in a variety of cells of DS patients (see Kedziora and Bartosz, 1988; Sinet, 1982). Because alterations in free radical metabolism may be involved in neuronal death and may be associated with a number of pathological manifestations of DS, it is important to understand the role of free radical metabolism in cognitive impairments of DS, the topic discussed in this chapter.

Effects of low selenium diets on antioxidant status and MPTP toxicity in mice

To investigate the role of chronic oxidative stress in MPTP neurotoxicity, C57BL mice were maintained 6-8 weeks on diets deficient in nutrients essential to cellular antioxidant defenses, selenium (Se) and alpha-tocopherol (vit E), and the effects on tissue antioxidant status and MPTP toxicity were evaluated relative to controls on supplemented diets. Activities of the major antioxidant enzymes, glutathione peroxidase (GPx), catalase, and superoxide dismutase, and levels of malondialdehyde as a marker for oxidative stress, were measured in brain, lung, liver and blood. Caudate depletion of dopamine and its metabolites served as a measure of MPTP neurotoxicity. For mice on the Se deficient diet, levels of the selenoenzyme GPx decreased from 50% in brain to 90% in blood. No compensatory changes in the activities of the other antioxidant enzymes were observed and addition of vit E to the diet did not alter antioxidant enzyme activities or malondialdehyde levels. In animals not treated with MPTP, the Se deficient diet significantly increased malondialdehyde only in liver. No protective effect of the antioxidant supplements against caudate depletion of dopamine and its metabolites were observed. However, malondialdehyde levels were increased in the brains of MPTP treated mice on the low Se diets, suggesting the possibility of secondary oxidative damage to tissues accompanying the destruction of substantia nigra neurons by MPTP.

Neuronal-specific expression of human copper-zinc superoxide dismutase gene in transgenic mice: animal model of gene dosage effects in Down's syndrome

It has been suggested that copper-zinc superoxide dismutase (CuZn SOD) increment, by accelerating hydrogen peroxide formation, might promote oxidative damage within trisomy 21 cells and might be involved in the various neurobiological abnormalities found in Down's syndrome such as premature aging and Alzheimer-type neurological lesions. In order to test this hypothesis, we have developed strains of transgenic mice carrying the human CuZn SOD gene. The human transgene expression resulted in increased CuZn SOD activity predominantly in the brain (1.93 fold). Immunohistochemical and in situ hybridization analysis of brain sections revealed that human CuZn SOD protein and mRNA was preferentially expressed in neurons, particularly in pyramidal cells of Ammon's horn and granule cells of gyrus dentate. The amount of thiobarbituric acid (TBA)-reactive material was significantly higher in transgenic brains compared to controls, strongly suggesting an increased level of peroxidation in vivo. These results support the notion that CuZn SOD gene dosage effect could play a role in the pathogenesis of rapid aging features in the brain of Down's syndrome patients.

Uptake and distribution in rat brain of organic and inorganic selenium

Polyunsaturated fatty acids (PUFAs) occur in relatively high amounts in phospholipids of the synapses. PUFAs may thus determine the fluidity of the synaptosomal membrane and, hereby, they may regulate the neuronal transmission. It was therefore tempting to suggest a system in the brain, that inhibits autooxidation of PUFAs. In order to trace such a protection system, Wistar rats were equally loaded with 4500 kBq of 75-Se either as selenite or as L-Se-methionine. By means of gradient ultracentrifugation, particulate fractions of the brains were isolated, and the radioactivity as well as the glutathione-transferase and -peroxidase activities were estimated. The distribution of the two selenium components among the particulate fractions was different. Thus, selenite gave higher radioactivity in myelin, then followed by the light synaptosomal and the vesicular fraction. L-Se-methionine was more equally incorporated in all particulate fractions, although highest activity was found in the mitochondrial fraction. Myelin and synaptic vesicles were devoid of transferase activity. On the other hand, the synaptosomal fraction showed highest specific transferase activity. The glutathione peroxidase activity was highest in the myelin fraction, followed by the vesicular and the synaptosomal fractions. The data obtained thus support the idea that the PUFAs of the synaptic compartment are protected against peroxidation, at least in part, by the selenium containing glutathione peroxidase.

Aging-related changes in brain metabolism are altered by early developmental exposure to diazepam

To study the long-term effects of prenatal diazepam (DZ) exposure, 31P NMR (nuclear magnetic resonance) spectra and levels of thiobarbituric acid (TBA)-reactive material were measured in the brains of rats from 3 to 26 months of age. In control rats, there were aging-related increases in levels of TBA-reactive material, decreases in intracellular pH (pHi) and alterations in phosphocreatine (PCr) utilization. Prenatal (late gestational) DZ exposure induced lasting, dose-related and age-related alterations in levels of TBA-reactive material and pHi. The results indicate that the prenatal chemical environment can influence cellular metabolism throughout the lifetime of the organism, and that the process of aging can in turn interact with the consequences of prenatal drug exposure.

Platelet glutathione peroxidase and monoamine oxidase activity in schizophrenics with CT scan abnormalities: relation to psychosocial variables

We have previously reported that the activity in platelets of the important antioxidant enzyme glutathione peroxidase (GPx) is inversely correlated with computed tomographic (CT) measures of brain atrophy in a population of patients with chronic schizophrenia, suggesting that low GPx may be a vulnerability factor in those schizophrenic patients with structural brain abnormalities. The significance of this finding has now been explored in a larger clinical population by examining the relation of GPx and CT parameters to psychosocial variables and to the activity of platelet monoamine oxidase (MAO), which has also been reported to be altered in certain schizophrenic populations. In the present study, low platelet GPx and high brain atrophy were found to be associated with DSM-III diagnoses of nonparanoid schizophrenia, a high degree of chronicity, and a predominance of negative symptoms. Contrary to some literature reports, atrophy also correlated with age and length of illness among the schizophrenic patients, although the contribution of these factors was less than that of low GPx, which was itself not age dependent. The ventricle-brain ratio (VBR) and atrophy were highly correlated in a control group of affective disorder patients, but not in the schizophrenic group, where large VBRs were found predominantly in the DSM-III undifferentiated subgroup. The low-GPx/high-atrophy schizophrenic patients had normal platelet MAO levels, and MAO was significantly lower only in the paranoid subgroup, consistent with reported observations. There was no evidence for a neuroleptic-induced effect on either enzyme.

Vitamin E concentrations in human brain of patients with Alzheimer's disease, fetuses with Down's syndrome, centenarians, and controls

The concentration of vitamin E (alpha-tocopherol) was measured in samples of cortex from patients with Alzheimer's disease (AD), fetuses with Down's syndrome (DS), and also in a group of centenarians. The mean tocopherol concentrations in the two patient groups did not differ significantly from appropriate controls. When expressed per lipid the mean tocopherol concentration of the centenarians was greater than that of the controls but this reflected a significant decrease in the lipid concentration of the former group. These results indicate that neither the normal aging processes, Alzheimer's disease, nor the increased in vitro lipid peroxidation reported in fetuses with Down's syndrome result from a gross lack of alpha-tocopherol, or cause a significant depletion of the vitamin.

Early developmental exposure to benzodiazepine ligands alters brain levels of thiobarbituric acid-reactive products in young adult rats

Levels of thiobarbituric acid (TBA)-reactive material were measured in brain regions of 3-4 month-old rats following prenatal exposure to several benzodiazepine (BDZ) receptor ligands over gestational days 14-20. Prenatal exposure to diazepam (DZ) at 1.0 mg/kg/day markedly elevated levels of brain TBA-reactive material while exposure to a higher dose (2.5 mg/kg) induced a significant increase only in the hippocampus. Early exposure to the central-type BDZ agonist clonazepam as well as to the central-type antagonist Ro 15-1788 also increased brain levels of TBA-reactive material. Concurrent exposure to the higher dose of DZ partially attenuated the effect of Ro 15-1788. Prenatal exposure to the peripheral-type BDZ ligand PK11195 produced a profound increase in TBA-reactive products in all regions, and concurrent DZ exposure did not attenuate this effect, except in the basal ganglia. Measurement of TBA-reactive material from birth to 3 months indicated that the effect of prenatal exposure to DZ was not apparent until after 8 weeks of age. Acute in vitro exposure of adult and fetal tissue to DZ had no effect on TBA-reactive material. The results suggest an interference in the organization of cellular metabolism in the brain by developmental exposure to BDZ ligands.

Biochemical and clinical effects of an antioxidative supplementation of geriatric patients. A double blind study

Ninety seven geriatric patients from two Danish homes for old people accepted to participate in a blinded experiment designed to counteract ageing phenomena. The subjects were split into two groups, i.e., the verum and the placebo group. The verum group received daily for one year an antioxidative cocktail consisting of: 300 micrograms selenium as L-selenomethionine, 45 mg zinc, 270 mg vitamin C, 2.7 mg vitamin A, 6 mg vitamin B-6, and 465 mg vitamin E (d-alfatocopherol). Furthermore, in order to enhance exchange in polyenoic acids, each subject received daily 250 mg gamma-linolenic acid. The placebo groups received similar looking pills and capsules without the active components. During one year in the verum group, the whole blood selenium, the hydrogen-dependent glutathione peroxidase (GSH-Px) of erythrocytes, and the vitamin E level in serum was found increased compared to the pretreatment values and to the placebo group. No change could be traced in the t-butylhydroperoxide dependent GSH-Px, an enzyme that also assays the glutathione-s-transferase. During the same period of time, the fasting levels of serum fatty acids and the content of lipofuscin in erythrocytes were estimated. Compared to the pretreatment values, the lipofuscin level declined significantly and the level of w-3 penta- and hexaenoic acids increased in the verum, but not in the placebo group. During the study period, slight, but significant improvements in psychological scores could be traced. Furthermore, the assays of bloodflow in different areas of the brain surface (i.e., the ISI values) revealed a general trend to improvement in all areas, when the ISI values were compared during treatment with the pretreatment values and the values in the placebo group.

Selenium in chronic neurologic diseases. Multiple sclerosis and Batten's disease

The selenium levels in whole blood and the activity of glutathione peroxidase in hematogenous cells of normal Danes have been defined taking into account sex and confounding factors such as smoking and aging. No differences related to sex could be found with regard to the selenium level, and peroxidase activity assayed with hydrogen peroxide. However, the peroxidase activity assayed with t-butyl hydroperoxide was higher in females than in males (p less than .05). The peroxidase activities are dependent on age. Thus, the peroxidase levels assayed with both substrates show a minimum value in the age group from 40 to 50 yr for both smokers and nonsmokers. Smokers did show more homogeneous values as a function of age than nonsmokers. Smokers had significantly lower selenium values than nonsmokers, but glutathione peroxidase values identical with those of nonsmokers. Multiple sclerosis (MS) patients suffer from a chronic relapsing/remitting demyelinating disease. A theory explaining the pathogenesis of MS concerns increased stickiness of cellular plasma membranes, hampering normal vascular function of the brain. In agreement with that theory, the present communication demonstrates significantly lowered selenium values and lowered glutathione peroxidase activities of major types of hematogenous cells. In close agreement with these findings, hematogenous cells in MS show increased peroxidation rates. A nonblinded biochemical dietary experiment on MS patients showed that all abnormalities could be normalized by daily intake of selenium, vitamin E, and vitamin C. Batten's disease is a recessive inherited neurodegenerative disorder clinically characterized by progressive loss of vision, epilepsy, and dementia. Neuropathologically, this disease is characterized by storage of lipofuscin in nervous tissue. We have in a few cases documented a low selenium status and low glutathione peroxidase activities of hematogenous cells. As in MS, we normalized the biochemical abnormalities by an antioxidative treatment. Like in similar Finnish studies, the biochemical parameters can be normalized. Further, the Finnish studies indicate it possible by an antioxidative treatment to inhibit progression of the mental deterioration. The data presented will be discussed in relationship both to specific pathological parameters of the diseases and to the low dietary energy expenditures of handicapped immobile patients.

Glutathione peroxidase and CT scan abnormalities in schizophrenia

The search for morphological clues to the etiology of schizophrenia has led to widespread application of computed tomography (CT) scans in the examination of patients. These investigations have resulted in numerous reports over the past several years of brain atrophy and increased ventricle-brain ratios (VBR), suggestive of neuronal tissue damage, associated with the disorder. Altered activity of cellular antioxidant systems have been implicated in the neuronal cell loss that is associated with degenerative diseases of the central nervous system (CNS), but this phenomenon has not been investigated with respect to functional disorders like schizophrenia. A search for such a relationship in schizophrenics with evidence of brain atrophy has been initiated by measuring the activity of the important antioxidant enzyme glutathione peroxidase (GPx) in blood samples from a population of chronic schizophrenics and age- and sex-matched nonschizophrenic mental patients as controls. A strong negative correlation has been found between GPx activity in both isolated platelets and erythrocytes and CT scan measures of brain atrophy and VBR in the schizophrenics, but not in the control population, which exhibited comparable CT scan abnormalities. These observations suggest a unique relationship of GPx to the mechanism of tissue damage in the schizophrenics.

Increased glutathione peroxidase activity in erythrocytes in patients with Alzheimer's disease/senile dementia of Alzheimer's type

Glutathione peroxidase (GSH-Px) activity in erythrocytes was studied in 9 patients with Alzheimer's disease/senile dementia of Alzheimer's type (AD/SDAT) of ages 34-64 years and compared with that in 16 healthy controls of ages 21-66 years. The median GSH-Px activity in erythrocytes from AD/SDAT patients was 408, mu kat/1 (range 338-500 mu kat/1) and that from healthy controls 348, mu kat/1 (range 258-439 mu kat). This difference was significant (p less than 0.005) Wilcoxon rank test. Since there are great clinical and pathological similarities between AD/SDAT and the dementia of Down's syndrome (DS) patients and since both these groups of patients have increased activity of the selenium-dependent enzyme GSH-Px, it is suggested that there could be a similar metabolic background of the dementia. Many findings in the oxidative metabolism of DS suggest increased oxidative damage with an elevation of the turnover of superoxides to peroxides within cells and with a secondary biochemical modification such as increase in tissual GSH-Px activity. A similar mechanism with elevated peroxidation within cells might be responsible for the present finding of increased GSH-Px activity in erythrocytes and for the development of dementia in AD/SDAT.

Erythrocyte glutathione peroxidase and superoxide dismutase in Alzheimer's disease and other dementias

Activities of 2 enzymes protecting from free radical damage, erythrocyte glutathione peroxidase and superoxide dismutase, were measured in 4 patients with Alzheimer's disease, in 4 with multi-infarct dementia, in 1 with Huntington's disease and in 1 with Hakola-Nasu disease. In none of these dementing diseases the activities were diminished compared to controls.