Biomedical subjects

J C Copin

Publications and source records attributed to J C Copin.

32 records · Page 2Linked to original sources

PubMed1998

Trolox and 6,7-dinitroquinoxaline-2,3-dione prevent necrosis but not apoptosis in cultured neurons subjected to oxygen deprivation.

There is a growing body of evidence suggesting that apoptosis is involved in ischemic brain injury. Recent studies suggest that a rapid necrosis masked a more subtle apoptotic death in neurons subjected to oxygen deprivation in culture. To test this hypothesis, we treated cultured neurons with potential antinecrotic drugs during and after oxygen deprivation. The results show that 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-hydroxy-2,5,7, 8-tetramethylchroman-2-carboxylic acid (Trolox), which interfered with kainate receptor activation and lipid peroxidation respectively, prevented necrosis but allowed neurons to undergo apoptosis. Flow cytometric analysis of DNA degradation and hydrogen peroxide generation, as well as fluorescent microscopy of nuclear fragmentation revealed that apoptotic activity was higher in 6, 7-dinitroquinoxaline-2,3-dione-treated cells than in Trolox-treated cells. This difference in occurrence of apoptosis may be due to the difference in oxidative stress generated from these two different agents.

Animals↗

PubMed1998

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.

Animals↗

PubMed1997

Apoptosis in the striatum of rats following intraperitoneal injection of 3-nitropropionic acid.

The present study investigated the mechanism of cellular degeneration within the striatum following administration of the mitochondrial toxin, 3-nitropropionic (3-NP) acid. Internucleosomal fragmentation typical of apoptosis was present in the DNA of cells from the striatum of 3-NP-treated rats. DNA fragmentation was also evident in this region by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling. The data suggest that striatal cells die by apoptosis following administration of 3-NP.

Animals↗

PubMed1997

Blood-brain barrier disruption, HSP70 expression and apoptosis due to 3-nitropropionic acid, a mitochondrial toxin.

3-Nitropropionic acid (3-NP), a mitochondrial toxin, induces apoptosis in the striatum. We wanted to determine if there was a relationship between mitochondrial dysfunction, disruption of the blood-brain barrier (BBB), and apoptosis. BBB disruption following intrastriatal injection of 3-NP was assessed by Evans blue leakage, brain water content, and by the expression of the 70 kDa heat shock protein (HSP70) and mRNA. Apoptosis was assessed by in situ terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) and gel electrophoresis to detect internucleosomal DNA fragmentation. Microscopic evidence of Evans blue leakage due to 3-NP was present only 3 hr after injection. Both internucleosomal DNA fragmentation and TUNEL-labeling did not appear until 24 hr after injection. HSP70 (protein and mRNA) was also elevated by 24 hr. There was a quantitative increase in Evans blue leakage and brain water content due to 3-NP by 3 days after injection. Our results suggest that BBB disruption is an early event followed by increased HSP70 expression and apoptosis. We speculate that 3-NP damages endothelial cells, leading to vasogenic edema and apoptosis.

Animals↗

PubMed1996

Development of glial cells cultured from prenatally alcohol treated rat brain: effect of supplementation of the maternal alcohol diet with a grape extract.

The aim of this work was to investigate the effect of supplementation of a maternal alcohol diet with a grape extract on glial cell development. Glial cells were cultured during 4 weeks from cortical brain cells of the new born offspring in DMEM medium supplemented with fetal calf serum. Enzymatic markers of nerve cell development were measured (enolase isoenzymes and glutamine synthetase). Since alcohol consumption produces free radicals the antioxidant system superoxide dismutase was also investigated. Compared to the decrease found in only alcohol treated animals, all parameters except neuron-specific enolase were antagonized and even stimulated after grape extract supplementation. The effect was more important after only 1 month than 3 months of treatment. Also in the total brain an alcohol antagonizing effect and a glutamine synthetase activation were found. Our data demonstrate that addition of a grape extract to the maternal alcohol diet may partially or completely overcome the alcohol induced retardation of glial cell development.

Animals↗

PubMed1996

Oxygen deprivation but not a combination of oxygen, glucose, and serum deprivation induces DNA degradation in mouse cortical neurons in vitro: attenuation by transgenic overexpression of CuZn-superoxide dismutase.

The present work was designed to study the possible implication of apoptosis in ischemic neuronal death, a phenomenon that has been suggested to be involved in neurodegeneration following focal as well as global ischemia. In this study, mouse cortical neurons in primary culture were subjected to oxygen deprivation or oxygen, glucose, and serum deprivation to simulate hypoxia and "ischemia-like" conditions; also, cellular viability as well as DNA degradation were investigated. The results showed that DNA degradation occurred in neurons subjected to oxygen deprivation but not to oxygen and substrate deprivation together. This DNA degradation, resulting in a laddering by agarose gel electrophoresis, could be prevented by cycloheximide and actinomycin-D treatments, although these inhibitors were unable to reduce neuronal death. To investigate if DNA degradation could be elicited by an intracellular free radical generation during reoxygenation, transgenic neurons overexpressing copper-zinc superoxide dismutase were subjected to 9 h of oxygen deprivation and analyzed after 24 h of reoxygenation. The results showed a significant attenuation of DNA degradation in these cells and confirmed a possible relationship between reactive oxygen species and neuronal apoptosis. This study opens the way to further investigations regarding the involvement of an apoptotic process in necrotic neuronal death, and provides some new insights into the mechanisms underlying selective sensitivity of neuronal cells to oxygen and glucose deprivation.

Animals↗

PubMed1996

Modulation of oxygen-radical-scavenging enzymes by oxidative stress in primary cultures of rat astroglial cells.

Cytosolic and mitochondrial alterations induced by exposure of rat astroglial primary cultures to reactive oxygen species (ROS) generated by a xanthine/xanthine oxidase (X/XO) mixture or by lipopolysaccharide (LPS) have been investigated biochemically and immunochemically. In the presence of ROS generated by X/XO, a significant decrease in Cu,Zn superoxide dismutase (Cu,Zn-SOD) and in glutamine synthetase (GS) activity was observed whereas mitochondrial Mn-SOD activity and enzyme protein levels were significantly enhanced. Similar effects on GS, Cu,Zn- and Mn-SOD activities were observed by glucose/glucose oxidase treatment of the cells. Addition of LPS to the cell growth medium also specifically induces Mn-SOD synthesis but was without effect on Cu,Zn-SOD. It is suggested that in all these tested situations, hydrogen peroxide could represent a specific inducer of the observed phenomenon and it may therefore be considered as an intracellular messenger involved in the regulation of some aspects of astroglial oxidative metabolism, particularly the defence against ROS.

Animals↗

PubMed1995

The effect of ethanol on HSP70 in cultured rat glial cells and in brain areas of rat pups exposed to ethanol in utero.

Prenatal exposure to alcohol is associated with a cluster of symptoms called Fetal Alcohol Syndrome with a characteristic pattern of neuroanatomy and biochemical changes. In recent years it has been shown, that stress exposed cells rapidly increase transcription and translation of heat shock protein genes resulting in an increased appearance of these proteins. It has also been found that heat shock proteins, especially the HSP70 family play a role as molecular chaperons maintaining the native conformation of proteins and participating in protein transport in particular cellular compartments. The aim of this study was to determine the effect of chronic maternal alcohol consumption on HSP70 content in the different regions of the brain of the newborn rats as well as to examine in vitro the effect of ethanol on HSP70 content in cultured glial cells. Chronic maternal ethanol consumption resulted in increased HSP70 in the following regions of developing brain: hippocampus, cerebellum, olfactory bulbs, frontal cortex and septum. Moreover, ethanol applied in vitro, increased HSP70 content in primary astroglial cultures and astrocytes but not in oligodendrocyte cultures. The above described changes may be important in brain maturation and may play a role in Fetal Alcohol Syndrome.

Alcoholism↗

PubMed1995

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.

Animals↗

PubMed1995

70-kDa heat shock protein expression in cultured rat astrocytes after hypoxia: regulatory effect of almitrine.

Induction of heat shock proteins (Hsps), especially the 70-kDa family, is well observed in nervous tissues in response to various stressful conditions. By using rat astrocytes in primary culture, the expression of the inducible (Hsp70) and the constitutive (Hsc70) 70-kDa Hsps immunoreactivity of cells exposed to hypoxic conditions has been investigated. We observed that exposure of astroglial cells to an hypoxic-normoxic sequence induces a significant decrease of Hsc70 immunoreactivity. The presence of the heat inducible stress protein Hsp70 is never observed in hypoxic cells nor in control. Hsc 70 lowering is associated with ultrastructural alterations characterized by mitochondria swelling, formation of vacuoles and accumulation of dense material in the cell cytoplasm. The effects of addition of almitrine to the culture medium before and during hypoxia on Hsps immunoreactivity have been examined. The presence of the drug prevents the decrease of Hsc70 immunoreactivity induced by hypoxia. Furthermore, some ultrastructural improvement is observed in astroglial cells treated with almitrine suggesting some protecting role of Hsc70 on cell damage induced by hypoxia.

Almitrine↗

PubMed1994

Effects of Ca(II) ions on Mn(II) dynamics in chick glia and rat astrocytes: potential regulation of glutamine synthetase.

Previous studies have demonstrated that in glia and astrocytes Mn(II) is distributed with ca. 30-40% in the cytoplasm, 60-70% in mitochondria. Ca(II) ions were observed to alter both the flux rates and distribution of Mn(II) ions in primary cultures of chick glia and rat astrocytes. External (influxing) Ca(II) ions had the greatest effect on Mn(II) uptake and efflux, compared to internal (effluxing) or internal-external equilibrated Ca(II) ions. External (influxing) Ca(II) ions inhibited the net rate and extent of Mn(II) uptake but enhanced Mn(II) efflux from mitochondria. These observations differ from Ca(II)-Mn(II) effects previously reported with "brain" (neuronal) mitochondria. Overall, increased cytoplasmic Ca(II) acts to block Mn(II) uptake and enhance Mn(II) release by mitochondria, which serve to increase the cytoplasmic concentration of free Mn(II). A hypothesis is presented involving external L-glutamate acting through membrane receptors to mobilize cell Ca(II), which in turn causes mitochondrial Mn(II) to be released. Because the concentration of free cytoplasmic Mn(II) is poised near the Kd for Mn(II) with glutamine synthetase, a slight increase in cytoplasmic Mn(II) will directly enhance the activity of glutamine synthetase, which catalyzes removal of neurotoxic glutamate and ammonia.

Animals↗

PubMed1993

Almitrine prevents some hypoxia-induced metabolic injury in rat astrocytes.

During reperfusion of ischemic brain tissue, the production of reactive oxygen species initiates several modifications of the astroglial functional and ultrastructural integrity. During 24 h after ischemic treatment, modification of cellular superoxide free radical scavenging systems have been observed in primary culture of rat astroglial cell. Mitochondrial Mn superoxide dismutase activity (Mn-SOD) gradually decreases, whereas that of the cytosolic Cu,Zn form of the enzyme remains unaffected. We observed in parallel a significant decrease of glutamine synthetase (GS), an astrocyte specifically located enzyme. Addition of almitrine (dialylamine-4',6'-triazinyl 2')-1-(bis-parafluoro-benzydryl)-4-piperazine or dibucaine (a phospholipase A2 inhibitor) antagonizes the decrease of Mn-SOD activity, but does not affect modification of GS activity. Combined effects are observed by simultaneous addition of both drugs. Our data demonstrate that almitrine may increase the synthesis of some mitochondrial proteins, like Mn-SOD, and provide support for further study on the therapeutic potential of almitrine in ischemic astroglial cell injury.

Almitrine↗

PubMed1992

Free radical scavenging systems of rat astroglial cells in primary culture: effects of anoxia and drug treatment.

Hypoxic injury of rat astroglial cells in primary culture initiates several modifications of their functional integrity. A significant decrease of the cellular oxygen consumption was observed in astrocytes submitted to a 15 h low oxygen pressure. The addition of almitrine (dialylamino-4',6'-triazinyl 2')-1-(bis-parafluorobenzydryl)-4-piperazine, a chemoreceptor agonist, restored almost completely the respiratory activity of the hypoxia treated cells. In order to test the hypothesis that oxygen free radical formation may contribute to the cellular damage resulting from ischemia, the activities of the following antioxidant enzymatic systems have been determined in the cultured astrocytes: Cu,Zn- and Mn-superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), glutathione reductase (GSH-RED), and catalase (CAT). Only a significant and specific decrease of the Mn-SOD activity was observed after the hypoxia-normoxia exposure. The other oxygen radical scavenging systems were not modified. The addition of almitrine antagonized the decrease of the Mn-SOD activity observed in the low oxygen pressure treated cells, but results clearly point-out the importance of oxygen radical production in the astroglial response after hypoxic injury. A beneficial effect of almitrine toward the observed alteration has been underlined. It is suggested that some mitochondrial alterations could be related to some aspects of the astroglial hypoxic stress.

Almitrine↗

PubMed1991

Hypoxia induced metabolism dysfunction of rat astrocytes in primary cell cultures.

In order to study the astroglial contribution to hypoxic injury on brain tissue metabolism, modifications of glutamine synthetase (GS) lactate dehydrogenase (LDH) enolase and malate dehydrogenase activity produced by reduced oxygen supply have been determined in primary cultures of astrocytes prepared from newborn rat cerebral cortex. Enzymatic activities were measured immediately after the hypoxic treatment (9 h) and during post injury recovery. GS level is significantly decreased in response to low oxygen pressure and increased above control value during the post hypoxic recovery period. The magnitude of GS reduction by hypoxia depends on the age of the cells in culture. Lactate dehydrogenase and enolase levels were significantly enhanced during the two periods considered. No modification of the MDH level was observed. The synthesis of LDH isoenzymes containing mainly M subunits is specifically induced by hypoxia. Our results suggest that astroglial cells may represent a particularly sensitive target toward hypoxia injury in brain tissue. Low oxygen pressure available may modify some fundamental metabolical functions of these cells such as glutamate turnover and lactic acid accumulation.

Animals↗