Effect of ethanol on superoxide dismutase activity in cultured neural cells

Competition between ethanol clearance and retinoic acid biosynthesis in the induction of fetal alcohol syndrome

Several models have been proposed to explain the neurodevelopmental syndrome induced by exposure of human embryos to alcohol, which is known as fetal alcohol spectrum disorder (FASD). One of the proposed models suggests a competition for the enzymes required for the biosynthesis of retinoic acid. The outcome of such competition is development under conditions of reduced retinoic acid signaling. Retinoic acid is one of the biologically active metabolites of vitamin A (retinol), and regulates numerous embryonic and differentiation processes. The developmental malformations characteristic of FASD resemble those observed in vitamin A deficiency syndrome as well as from inhibition of retinoic acid biosynthesis or signaling in experimental models. There is extensive biochemical and enzymatic overlap between ethanol clearance and retinoic acid biosynthesis. Several lines of evidence suggest that in the embryo, the competition takes place between acetaldehyde and retinaldehyde for the aldehyde dehydrogenase activity available. In adults, this competition also extends to the alcohol dehydrogenase activity. Ethanol-induced developmental defects can be ameliorated by increasing the levels of retinol, retinaldehyde, or retinaldehyde dehydrogenase. Acetaldehyde inhibits the production of retinoic acid by retinaldehyde dehydrogenase, further supporting the competition model. All of the evidence supports the reduction of retinoic acid signaling as the etiological trigger in the induction of FASD.

Green tea supplementation in rats of different ages mitigates ethanol-induced changes in brain antioxidant abilities

Oxidative stress induced by chronic ethanol consumption, particularly in aging subjects, has been implicated in the pathophysiology of many neurodegenerative diseases. Antioxidants with polyphenol structures, such as those contained in green tea, given alone for 5 weeks in liquid Lieber de Carli diet followed by administration with ethanol for 4 weeks with ethanol have been investigated as potential therapeutic antioxidant agents in the brain in rats of three ages (2, 12, and 24 months). Ethanol consumption caused age-dependent decreases in brain superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase activities. In addition, ethanol consumption caused age-dependent decreases in the levels of GSH, selenium, vitamins, E, A and C, and beta-carotene and increases in the levels of oxidized glutathione (GSSG). Changes in the brain's antioxidative ability were accompanied by enhanced oxidative modification of lipids (increases in lipid hydroperoxides, malondialdehyde, and 4-hydroxynonenal levels) and proteins (increases in carbonyl groups and bistyrosine). Reduced risk of oxidative stress and protection of the central nervous system, particularly in young and adult rats, after green tea supplementation were observed. Green tea partially prevented changes in antioxidant enzymatic as well as nonenzymatic parameters induced by ethanol and enhanced by aging. Administration of green tea significantly protects lipids and proteins against oxidative modifications in the brain tissue of young and adult rats. The beneficial effect of green tea can result from the inhibition of free radical chain reactions generated during ethanol-induced oxidative stress and/or from green tea-induced increases in antioxidative abilities made possible by increases in the activity/concentration of endogenous antioxidants.

Paternal alcohol exposure: developmental and behavioral effects on the offspring of rats

The effect of paternal alcohol exposure on neurochemical and behavioral parameters was investigated using as a model system glial cells derived from newborn rat brain and cultured for 4 weeks. The total brain neurochemical parameters from rats born to mothers sired by an alcohol treated father were also investigated. Enzymatic markers of nerve cell development (enolase isoenzymes and glutamine synthetase) and the defense system (superoxide dismutase) against free radicals formed during alcohol degradation were measured in order to evaluate nerve cell damage. Behavioral locomotor tests (open-field, novelty-seeking, light/dark) were carried out to show long-lasting effects of paternal alcoholization on the offspring. Behavioral and developmental alterations were found until 1 year of age in the offspring and a significant growth retardation was observed in the males. Our results suggest that paternal alcohol exposure produces developmental and behavioral effects in the offspring. The consequence of either alcohol withdrawal during stage one spermatogenesis, or maternal diet supplementation with manganese during pregnancy were investigated. It was observed that some of the effects of paternal alcohol exposure on the offspring may be reversed by these treatments.

Cortical cell plasma membrane alterations after in vitro alcohol exposure: prevention by GM1 ganglioside

Using choleratoxin/antitoxin immunohistochemistry, this study examined the effects of in vitro alcohol exposure on the morphology of cell plasma membranes in mixed fetal rat cortical cultures, and assessed the neuroprotective effects of exogenous monosialoganglioside (GM1). Gangliosides are involved in critical biological functions, including maintenance of membrane integrity. Plasma membranes are directly affected by alcohol exposure through multiple mechanisms. Results indicate that exposure to alcohol altered plasma membrane morphology as assessed by staining for the surface distribution of membrane GM1. Pretreatment with endogenous GM1 ameliorated the alcohol-induced alterations.

Antioxidant defense system in lung of male and female rats: interactions with alcohol, copper, and type of dietary carbohydrate

Male and female rats were used to investigate the effects of type of dietary carbohydrate (CHO), copper, and ethanol consumption on lung antioxidant enzyme activities and levels of phosphorylated compounds in whole blood. Copper-deficient female rats exhibited a greater degree of copper deficiency than males, as assessed by hepatic copper concentration and hepatic copper superoxide dismutase (CuSOD) activity. However, copper-deficient male rats fed fructose-containing diets exhibited greater growth retardation, anemia, and heart hypertrophy than females consuming the same diets and males fed starch. In addition, one of 10 copper-deficient male rats that ate a fructose-based diet and drank water and one of 10 copper-deficient male rats that ate a starch-based diet and drank ethanol died. Copper-deficient, starch-fed males exhibited the highest activities of glutathione peroxidase (GSH-Px) and catalase as compared with fructose-fed rats. Ethanol consumption elevated the activities of GSH-Px and catalase. Copper-deficient female rats exhibited higher catalase but lower GSH-Px activities than males. It is suggested that in copper deficiency, the ability to increase antioxidant enzyme activities in rats consuming starch is greater than in rats consuming fructose. Rats fed starch are provided with a greater degree of protection against oxidative damage than rats fed fructose. In addition, polyphosphorylated compounds in blood were reduced in copper-deficient male rats that consumed fructose-based diets. This may impair supply of oxygen to tissues.

Effect of manganese on the development of glial cells cultured from prenatally alcohol exposed rats

Maternal alcohol abuse is known to produce retardation in brain maturation and brain functions. Using cultured glial cells as a model system to study these effects of alcohol we found an alcohol antagonizing property for manganese (Mn). Mn was added to the alcohol diet (MnCl2 25 mg/l of 20% v/v ethanol) of pregnant rats. Glial cells were cultured during 4 weeks from cortical brain cells of pups born to these mothers. Several biochemical parameters were examined: protein levels, enzymatic markers of glial cell maturation (enolase and glutamine synthetase), superoxide dismutase a scavenger of free radicals produced during alcohol degradation. The results were compared to appropriate controls. A beneficent effect of Mn was observed for the pups weight which was no more significantly different from the control values. Protein levels, enolase and glutamine synthetase activities were increased mainly during the proliferative period when Mn was added to the alcohol diet compared to the only alcohol treated animals. This Mn effect was not found for superoxide dismutase in cultured glial cells but exists in the total brain of the 2 week-old offspring. In the total 2 and 4 week-old brain the alcohol induced decrease of enolase and glutamine synthetase was also antagonized by the Mn supplementation. Our data suggest that Mn may act as a factor overcoming at least partially some aspects of alcohol induced retardation of nerve cell development.

Fetal alcohol syndrome: the vulnerability of the developing brain and possible mechanisms of damage

Fetal alcohol exposure has multiple deleterious effects on brain development, and represents a leading known cause of mental retardation. This review of the effects of alcohol exposure on the developing brain evaluates results from human, animal and in vitro studies, but focuses on key research issues, including possible mechanisms of damage. Factors that affect the risk and severity of fetal alcohol damage also are considered.

Alcohol and white matter development--a review

This is a review of the literature on the effects of alcohol on white matter development. For many years, human and animal studies have reported the vulnerability of developing white matter to the effects of alcohol. However, until recently, studies on alcohol and white matter were limited by existing technology. New technology documenting the presence of neurotransmitter receptors and ion channels on glial cells now provides a new focus for research on alcohol and white matter development. New research using new technology should enlarge our knowledge of the role of glial cells in brain damage associated with alcohol exposure during development.

Increase in catalase activity in developing rat brain cell reaggregation cultures in the presence of ethanol

The aim of this investigation was to study the effects of ethanol on antioxidant enzymes in the developing brain, using reaggregation cultures of fetal rat brain cells as a model. The cultures were grown in the presence of 20 and 40 mM ethanol from day 2 until day 44 of the culture period, corresponding to a period in vivo from gestational day 17 to postnatal day 37. The catalase (EC 1.11.1.6) activity was consistently increased at all observation periods, from culture day 11 to day 44, by both doses of ethanol, and an immunoblot showed that the amount of catalase protein was markedly increased. The activities of manganese and copper-zinc superoxide dismutase (EC 1.15.1.1) and glutathione peroxidase (EC 1.11.1.9) were largely unaffected.

Neuroscience research: how has it contributed to our understanding of alcohol abuse and alcoholism? A review

Alcohol abuse and alcoholism are the greatest substance abuse problems in the United States today and contribute to numerous medical and social problems. To deal with many of these problems, an understanding of how alcohol acts on the brain is extremely important. Advances in neuroscience research have provided significant clues about where and how alcohol works on the brain. Alcohol clearly acts on membrane function, altering such processes as ion movements and neurotransmitter interactions with their receptors. Although these alcohol-induced alterations are presumed to relate to changes in behavior, this has not been clearly established. However, alcohol research is on the threshold of making a giant leap forward in our understanding the etiology of alcoholism.

Influence of copper status on the response to acute ethanol exposure in rats

An acute dose of ethanol was used to investigate the biochemical response of tissues with a compromised antioxidant defense system to a surge of oxygen radical production. The copper (Cu)-deficient rat served as the animal model for this study based on its compromised antioxidant defense system. Rats were fed control (10 micrograms Cu/g) or Cu-deficient (0.2 microgram Cu/g) diet for 14 days. In order to minimize secondary effects associated with chronic Cu deficiency, the chelator triethylenetetramine was added to the Cu-deficient diet to shorten the time required for the induction of Cu deficiency. On day 14, rats were gavaged with ethanol (4.5 g/kg b.wt.) or saline and killed 9 hours postgavage. Rats fed the Cu-deficient diets had lower liver superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities than controls. Ethanol treatment had no effect on liver CuZnSOD or Gpx activity, while MnSOD activity was higher than saline control levels following EtOH treatment. Despite low GPx and SOD activity, Cu-deficient rats did not exhibit higher hepatic thiobarbituric acid reacting substances (TBARS) than controls; in fact, hepatic microsomal TBARS were lower in saline-treated Cu-deficient rats relative to Cu-sufficient rats. Ethanol treatment resulted in higher whole homogenate and mitochondrial TBARS than in saline-gavaged rats. Copper status did not influence hepatic TBARS production in response to an acute EtOH load. These data suggest that compensatory mechanisms contribute to the protection of the liver from excessive free radical production in this model of Cu deficiency.

Combined effects of ethanol and manganese on cultured neurons and glia

Manganese is essential for normal development and activity of the nervous tissue. Mn2+ ions are involved in protein synthesis and may prevent free radical damage. Since it is now established that alcohol degradation may produce free radicals, we studied the effect of Mn2+ on ethanol induced alterations using cultured nerve cells as an experimental model of the central nervous system. Neurons and glial cells were cultured from rat brain cortex; a tumoral rat glial cell line (C6) was also examined. We measured enzymatic markers of nerve cell maturation (enolase, glutamine synthetase) and superoxide dismutase, a scavenger of free radicals; all these enzymes being activated by Mn2+ ions. Only for the glial cell types an alcohol antagonizing effect was found when Mn2+ was combined with ethanol. Neurons were not sensitive to that Mn2+ effect.

Blood cell superoxide dismutase and enolase activities as markers of alcoholic and nonalcoholic liver diseases

Monitoring of chronic alcoholism would be facilitated by using sensitive biochemical markers in blood cells, mainly to detect differences between alcoholic subjects with or without liver injury. We propose two types of markers: the first one is superoxide dismutase (SOD) activity involved in the conversion of superoxide radicals (O2-.) formed during acetaldehyde oxidation by xanthine oxidase after chronic alcohol consumption; the second one is enolase activity with both isoenzyme forms: nonneuronal enolase (NNE) and neuron specific enolase (NSE) which has been shown to be modified in many injuries related to the glycolytic pathways. For SOD activity we found a significant increase in alcoholic patients with liver injury and mainly in cirrhotic patients with ascitis. Both enolase activities were also found to be significantly increased in alcoholic patients with liver injury but NNE activity was also increased in alcoholics without apparent liver disease. Our results suggest that increased activity of SOD and NSE in blood cells may be related to liver injury mainly in alcoholism while increased NNE activity may also be a marker of alcohol abuse without liver injury.

Responses in astrocytic C6 glioma cells to ethanol and dibutyryl cyclic AMP

Late passage C-6 glioma cells exhibit astrocytic properties as shown by a characteristic cell morphology and by high levels of the astrocytic cell maker glutamine synthetase (GS). In this study the effects of ethanol (0.2%-1.0% w/v) on the pattern of dibutyryl cyclic AMP (dBcAMP, 1 mM)-induced differentiation were examined using cell number and DNA content as indices for proliferation and cell morphology and GS activity to evaluate differentiation. Differences were observed in the susceptibility of cells to dBcAMP alone, ethanol alone, or simultaneous exposure to both drugs, when cultures were compared at logarithmic and postconfluent phases of growth. Exposure to dBcAMP decreased cell proliferation, induced a characteristic change in cell shape and increased GS activity. In logarithmic phase, simultaneous exposure of cells to ethanol and dBcAMP delayed the dBcAMP-induced change in cell shape and attenuated the mitosis-restricting properties of exposure to dBcAMP. Furthermore, GS activity was greater in dually treated cultures than in cultures treated with dBcAMP alone. We interpret this higher enzyme activity to be the consequence of increased cell-cell contact resulting from larger numbers of cells in the dually treated cultures, coupled with a subsequent dBcAMP-induction of this cytosolic enzyme. In postconfluent cultures, ethanol-exposure did not statistically alter DNA content; whereas GS activity was lower, suggesting that synthesis of GS may be impaired by cellular exposure to ethanol. Furthermore, enzyme activity was also lower in cultures treated with dBcAMP in concert with ethanol than in those treated with dBcAMP alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol on adenosine triphosphatase and enolase activities in rat brain and in cultured nerve cells

The effect of alcohol on enzymes involved in energy metabolism of nervous tissue were analyzed, in vivo after acute and chronic ethanol administration to rats and in vitro by addition of 50 mM and 100 mM ethanol to the medium of cultured nerve cells: chick neurons, chick glial cells, a neuronal cell line (MT17) and a glial tumoral cell line (C6). The parameters we measured were (Na+, K+), Mg2+ and ecto Ca2+, Mg2+ ATPase activities involved in transport phenomena and enolase activities (non neuronal NNE and neuron specific enolase NSE) as markers of nerve cell maturation. In vivo, after chronic ethanol administration (Na+, K+) ATPase activity was increased while Mg2+ dependent activity was not affected. Enolase activity was decreased. Acute ethanol administration decreased (Na+, K+) ATPase activity, while Mg2+ dependent activity was not affected. In cultured nerve cells ethanol effect was dose, time and cell type dependent; alterations of the cell membrane by trypsinization of the tissue before seeding modifies the effect of ethanol on the enzymes we analyzed. Our results suggest that alcohol effect on nerve cells depends mainly on the lipoprotein structure of the cell membranes which may have different properties from one cell type to another.

Superoxide dismutase activity in brains from chronic alcoholics

CuZn superoxide dismutase (SOD) and Mn SOD activities were analyzed in hypothalamus, nucleus caudatus, hippocampus and cortex gyrus cinguli from 12 chronic alcoholics and from 16 controls. The CuZn SOD activities were slightly lower and the Mn SOD activities were slightly higher in the brain pieces from chronic alcoholics compared to the controls. The slight differences found can hardly be assigned etiological importance in the degenerative processes in brain tissue connected with chronic alcoholism.

Regional distribution of superoxide dismutase in rat brain during postnatal development

Superoxide dismutase in nervous system protects readily oxidizable compounds such as catecholamines against toxic effects of oxygen. We investigated superoxide dismutase activity during development in 5 brain regions selected for a wide range of catecholamine concentration and turnover: cerebellum, neocortex, striatum, hypothalamus and medulla-pons. The cytosolic and the particulate enzyme were measured from birth to 6 months of age. In cerebellum the cytosolic enzyme shows considerable activity on the first postnatal days; the particulate enzyme is less active, both reach a maximum at 3 months. In cortex and striatum both activities were low during the postnatal days and reach a plateau at 3 months. In hypothalamus both activities are higher during the postnatal days and reach a maximum at 3 months. In medulla-pons the values are 2 times higher than in all other regions; the cytosolic enzyme reaches a maximum at 2 months whereas the particulate enzyme reaches a plateau at 3 months. Thus our results show an increase of superoxide dismutase activity during development in all brain regions; the highest activities were found in regions with high catecholamine content.

Superoxide dismutase activity in rat brain during acute and chronic alcohol intoxication

The effect of acute and chronic ethanol administration on rat brain superoxide dismutase (SOD) activity was studied. Intraperitoneal injections of ethanol led to an inhibition of SOD activity. When ethanol was fed as the sole fluid, the SOD activity decreased progressively, reaching a plateau after 6 weeks of treatment. Withdrawal of ethanol produced a recovery of control values within 48 hr. SOD activity was also decreased in rats born from ethanol-drinking mothers. Inhibition of SOD activity by ethanol may allow an accumulation of cytotoxic O2 - radicals; this may account for some nervous system disorders during alcohol intoxication.