g(m1)-ganglioside and Hypoxia

Oligodendroglia play an important role in axonal conduction in the CNS and are sensitive to oxidative toxicity induced by glutamate in the absence of ionotropic glutamate receptors. In this study, oligodendrocyte signalling cascades were examined, in response to glutamate-induced oxidative injury and to excitotoxicity. Rat cortical oligodendrocytes, differentiated in culture, were highly vulnerable to glutamate-induced cell death. Competitive inhibition of cystine uptake and increased oxidative stress appeared responsible for this death, and caused an accumulation of intracellular peroxides as well as chromatin fragmentation and condensation. Glutamate receptor subtype agonists (quisqualate, ibotenate) known to inhibit cystine uptake were cytotoxic, but not NMDA itself; moreover, glutamate receptor antagonists were not protective. Oligodendrocytes were also vulnerable to overactivation of glutamate receptors, as kainic acid and AMPA proved to be toxic. AMPA toxicity required the presence of cyclothiazide, suggesting rapid desensitization of AMPA receptors. Glutamate-induced oxidative stress and kainate/AMPA receptor stimulation activated the mitogen-activated protein kinase (MAP kinase) pathway, as well as the transcription factor ELK. However, MAP kinase kinase inhibitors only protected against injury from glutamate-induced oxidative stress. Oligodendrocytes were sensitive to oxygen-glucose deprivation injury as well, in a MAP kinase dependent fashion. Glutamate toxicity may conceivably be operative in neuropathological conditions that disrupt neuronal/oligodendrocyte interactions in axons, e.g. multiple sclerosis and ischaemia-reperfusion injury.

Topics: 2',3'-Cyclic-Nucleotide Phosphodiesterases; Animals; Animals, Newborn; Annexin A5; Blotting, Western; Cell Death; Cell Survival; Cells, Cultured; Cerebral Cortex; Chromatin Assembly and Disassembly; Cystine; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Excitatory Amino Acids; Fluoresceins; G(M1) Ganglioside; Glial Fibrillary Acidic Protein; Glucose; Glutamic Acid; Hypoxia; Immunohistochemistry; Indoles; JNK Mitogen-Activated Protein Kinases; Kainic Acid; MAP Kinase Kinase 4; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Myelin Basic Protein; Myelin Proteins; Myelin-Associated Glycoprotein; Nogo Proteins; Oligodendroglia; Oligopeptides; Peroxides; Phosphorylation; Quinoxalines; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Receptors, Cell Surface; Signal Transduction; Time Factors

To investigate the protective effect of monosialoganglioside (GM1) on injury induced by oxygen glucose deprivation/reperfusion (OGD/Rep) in rat hippocampal slices.. The protective effects of GM1 on hippocampal slices after OGD/Rep were observed by detecting the light transmittance (LT) changes of rat hippocampal slices and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining of rat hippocampal slices.. (1) In four groups treated with 0 (control), 0.1, 1.0, 10 micromol/L GM1, the peak of light transmittance (LT) in the slices treated with 1.0 micromol/L GM1 was significantly lower than that of the control and the group treated with 0.10 micromol/L GM1 (P < 0.01, ANOVA), while the peak of LT in the slices treated with 10.0 micromol/L GM1 was significantly lower than that of the other groups (P < 0.01, ANOVA). The time to reach the peak of LT in four groups was significantly different from each other (P < 0.05, Kruskal-Wallis test). The time to reach the peak of LT in the group treated with 1 micromol/L GM1 was the significantly longer than that in the control (P < 0.01, Mann-Whitney U test). (2) There was characteristic dose-response relationship between GM1 and TTC staining of rat hippocampal slices. In the five groups, treated with 0 (control), 0.01, 0.1, 1.0, 10 micromol/L GM1 respectively, TTC staining in the group treated with 1 micromol/L GM1 was the deepest (P < 0.05 vs. control, 0.01 and 0.1 micromol/L GM1 group, ANOVA), and the next was in the group treated with 10 micromol/L GM1 (P < 0.05 vs. control and 0.01 micromol/L GM1 group, ANOVA).. GM1 could protect injury induced by OGD/Rep in rat hippocampal slices effectively in vitro.

Topics: Animals; G(M1) Ganglioside; Glucose; Hippocampus; Hypoxia; In Vitro Techniques; Male; Oxygen; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Brain neurotransmitter content and uptake activity were assessed in the brains of 7-day-old rats 15 min after exposure to hypoxia (8% O2-92% N2) for 3 hr. Glutamate, dopamine and choline uptake were decreased in the striatum, hippocampus and frontal cortex of the hypoxic animals. Moreover, the content of glutamate, dopamine and serotonin as well as the acidic metabolites of the two biogenic amines increased in the same tissues. Acetylcholine content was decreased in all three brain regions as well. Treating the animals with GM1 ganglioside before the insult prevented all neurochemical changes in the hypoxic neonatal brain. GM1 also prevented an hypoxia-induced decrease in phorbol ester binding. Finally, GM1 ganglioside reduced the mortality rate resulting from the hypoxic insult. Our results along with those in the literature suggest that GM1 might be useful for combating the pathology associated with perinatal hypoxia.

Topics: Animals; Animals, Newborn; Brain Chemistry; Dopamine; Female; G(M1) Ganglioside; Glutamic Acid; Hypoxia; Neurotransmitter Agents; Pregnancy; Protein Kinase C; Rats; Serotonin

Rat hearts made hypoxic for 20 min by perfusion with 95% N2/5% CO2 and reoxygenated for 20 min in a Langerdorff apparatus showed a dose-dependent reduction of lactate dehydrogenase release when incubated with ganglioside GM1 (0.1-10 microM). The decline of contractile force during hypoxia was also reduced dose dependently in the presence of GM1. Similar effects were observed in hearts obtained from animals treated i.p. with 40 mg/kg GM1 for 14 days. The levels of Na+,K(+)-ATPase in ventricular tissue were also reduced after hypoxia-reoxygenation and the reduction was prevented in hearts from GM1-treated animals. GM1 (1-30 microM) reduced the functional response to field stimulation of adrenergic nerve terminals in isolated atria. Rat atria made hypoxic in glucose-free media maintained normal stores of tissue noradrenaline in the presence of 1 microM GM1. In the rabbit, GM1 (40 mg/kg i.p. for 4 days) reduced the alterations of the ST segment of the ECG during acute occlusion of the left descending and circumflex coronaries artery. In conclusion, ganglioside GM1 reduces some effects of hypoxia-reoxygenation in the heart, through still unknown mechanisms.

Topics: Animals; Ca(2+) Mg(2+)-ATPase; Electric Stimulation; Electrocardiography; G(M1) Ganglioside; Heart; Hypoxia; In Vitro Techniques; Male; Myocardial Contraction; Norepinephrine; Rabbits; Rats; Rats, Wistar; Sodium-Potassium-Exchanging ATPase; Sympathetic Nervous System

Topics: Abnormalities, Drug-Induced; Animals; Animals, Newborn; Astrocytes; Biological Transport; Body Water; Cell Size; Cells, Cultured; Cerebral Cortex; Cocaine; Female; Fetal Diseases; G(M1) Ganglioside; Glutamates; Glutamic Acid; Hypoxia; Maternal-Fetal Exchange; Neurons; Potassium; Pregnancy; Rats; Rats, Sprague-Dawley

Exposure of 7-day-old rats to 7% oxygen/balance nitrogen for 2 h results in selective changes of cholinergic, serotonergic, and dopaminergic neuronal markers in the frontal cortex, hippocampus, and striatum when evaluated 3 weeks after the insult. There is also about a 15% deficiency in brain weight. Treatment with GM1 ganglioside, 50 mg/kg i.p., for 2 days before and for 3 weeks after the hypoxic insult partially corrects the neurodevelopmental abnormalities including the deficiency in brain weight. We conclude that GM1 ganglioside might have therapeutic potential for treating suspected neonatal hypoxia.

Topics: 3,4-Dihydroxyphenylacetic Acid; Acetylcholine; Animals; Animals, Newborn; Brain; Choline; Corpus Striatum; Dopamine; Frontal Lobe; G(M1) Ganglioside; Hippocampus; Hydroxyindoleacetic Acid; Hypoxia; Neurons; Neurotransmitter Agents; Organ Size; Rats; Serotonin

Excitatory dicarboxylic amino acid neurotransmitters, particularly glutamate, have been implicated in mediating neuronal cell injury in brain ischemia-anoxia, epilepsy, and stroke. Glutamate neurotoxicity has been demonstrated in several in vitro models, as well as its prevention by a variety of agents, including several sialic acid-containing glycosphingolipid species, gangliosides. We have now examined ganglioside effects in anoxic exposed cultures of granule cells from Postnatal Day 8 rat cerebellum. Cells between 10 and 12 days in vitro were placed into an anoxic atmosphere or subjected to a chemical model of anoxia by a pulse exposure to rotenone. Widespread neuronal degeneration of neuronal cell bodies and their associated neurite network was seen the following day. These effects on cell vitality at the morphological level were quantitatively confirmed by measuring the photometric reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide to a blue formazan product. This neuronal injury was abolished by the specific N-methyl-D-aspartate receptor noncompetitive antagonists Mg2+, phencyclidine and MK-801, suggesting that this subtype of glutamate receptor is involved in the pathogenesis of anoxic granule cell injury. Pretreatment for 30 to 60 min or more or concurrent treatment with ganglioside GM1 largely prevented the ensuing neuronal death (ED50 = 25 microM), even 4 days later. Degeneration induced by exogenous glutamate was equally reduced. Asialo GM1 (lacking sialic acid) was ineffective. These results are consistent with the observed beneficial effects of the gangliosides in ischemic brain injury models in vivo.

Topics: Animals; Cell Survival; Cells, Cultured; Coloring Agents; G(M1) Ganglioside; Gangliosides; Hypoxia; Microscopy, Phase-Contrast; Neurons; Nitrogen; Rotenone; Tetrazolium Salts; Thiazoles