Glutamate triggers internucleosomal DNA cleavage in neuronal cells

Kure, Shigeo; Tominaga, Teiji; Yoshimoto, Takashi; Tada, Keiya; Narisawa, Kuniaki

doi:10.1016/0006-291x(91)91330-f

Cited by 275 publications

(90 citation statements)

References 21 publications

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“…The initial evidence for an apoptotic mechanism was that internucleosomal DNA fragmentation was triggered by glutamate in cultured cortical neurons (Kure et al, 1991). However, later studies showed that this could be attributable to decreased glutathione instead of the conventional receptor-mediated toxicity (Murphy et al, 1989;Ratan et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of Cell Death Induced by the Mitochondrial Toxin 3-Nitropropionic Acid: Acute Excitotoxic Necrosis and Delayed Apoptosis

1997

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Impaired energy metabolism may play an important role in neuronal cell death after brain ischemia and in late-onset neurodegenerative diseases. Both excitotoxic necrosis and apoptosis have been implicated in cell death induced by metabolic impairment. However, the factors that determine whether cells undergo apoptosis or necrosis are not known. In the present study, metabolic impairment was induced by 3-nitropropionic acid (3-NP), a suicide inhibitor of succinate dehydrogenase. Treatment of cultured rat hippocampal neurons with 3-NP resulted in two types of cell death with distinct morphological, pharmacological, and biochemical features. A rapid necrotic cell death, characterized by cell swelling and nuclear shrinkage, could be completely prevented by the NMDA receptor antagonist MK-801 (10 M) and dose-dependently potentiated by low micromolar levels of extracellular glutamate. A slowly evolving apoptotic death, characterized by nuclear fragmentation, was not attenuated by MK-801 but was prevented by cycloheximide (1 g/ml). The combination of MK-801 and cycloheximide resulted in an almost complete protection against 3-NP-induced cell death. DNA fragmentation, detected by the terminal deoxynucleotidyl transferase-mediated dUTP-X 3Ј nick end-labeling technique, was a late event in apoptosis and also occurred after necrotic cell death. ATP depletion was an early event in the 3-NP-induced neuronal degeneration, and the decline in ATP was exacerbated by glutamate. We conclude that 3-NP triggers two separate cell death pathways: an excitotoxic necrosis as a result of NMDA receptor activation and a delayed apoptosis that is NMDA receptor-independent. Mildly elevated levels of extracellular glutamate shift the cell death mechanism from apoptosis to necrosis.Key words: energy metabolism; succinate dehydrogenase; 3-nitropropionic acid; excitotoxicity; apoptosis; necrosis; nuclear fragmentation; TUNEL; ATP Neuronal function and survival depend on a continuous supply of glucose and oxygen, used to generate ATP through glycolysis and mitochondrial respiration. A perturbation in energy metabolism during conditions such as ischemia, stroke, and brain trauma may cause irreversible neuronal injury. An age-related decline in energy metabolism also may contribute to neuronal loss during normal aging, as well as in neurodegenerative diseases (Wallace, 1994;Beal, 1995).There are discrepancies in the findings regarding the mechanisms of neuronal cell death after metabolic impairment. A large body of evidence supports the "secondary excitotoxicity" hypothesis that a loss of ATP leads to membrane depolarization, removal of the voltage-dependent Mg 2ϩ block of the NMDA receptor, and subsequent activation of NMDA receptor (for review, see Beal, 1992). Both in vivo and in vitro studies have shown that metabolic inhibitors potentiate glutamate and NMDA toxicity (Weller and

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Section: Discussionmentioning

confidence: 99%

Mechanisms of Cell Death Induced by the Mitochondrial Toxin 3-Nitropropionic Acid: Acute Excitotoxic Necrosis and Delayed Apoptosis

1997

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“…Addition of cortisol 48 h before tissue excision prevented these pathological changes, although mild cytopathology could be observed in some of the sections. Several studies have suggested the involvement of apoptosis in insult-induced neuronal degeneration (25)(26)(27)(28). We therefore examined whether the protective effect of cortisol could also be demonstrated by analysis of internucleosomal DNA fragmentation, a phenomenon associated with apoptosis (Fig.…”

Section: Induction Of Gs Expression By Glucocorticoids Protectsmentioning

confidence: 99%

Glutamine synthetase protects against neuronal degeneration in injured retinal tissue

Gorovits

Avidan

Avisar

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

126

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The neurotransmitter glutamate is neurotoxic when it is accumulated in a massive amount in the extracellular f luid. Excessive release of glutamate has been shown to be a major cause of neuronal degeneration after central nervous system injury. Under normal conditions, accumulation of synaptically released glutamate is prevented, at least in part, by a glial uptake system in which the glia-specific enzyme glutamine synthetase (GS) plays a key role. We postulated that glial cells cannot cope with glutamate neurotoxicity because the level of GS is not high enough to catalyze the excessive amounts of glutamate released by damaged neurons. We examined whether elevation of GS expression in glial cells protects against neuronal degeneration in injured retinal tissue. Analysis of lactate dehydrogenase eff lux, DNA fragmentation, and histological sections revealed that hormonal induction of the endogenous GS gene in retinal glial cells correlates with a decline in neuronal degeneration, whereas inhibition of GS activity by methionine sulfoximine leads to increased cell death. A supply of purified GS enzyme to the culture medium of retinal explants or directly to the embryo in ovo causes a dose-dependent decline in the extent of cell death. These results show that GS is a potent neuroprotectant and that elevation of GS expression in glial cells activates an endogenous mechanism whereby neurons are protected from the deleterious effects of excess glutamate in extracellular f luid after trauma or ischemia. Our results suggest new approaches to the clinical handling of neuronal degeneration.Glutamate neurotoxicity plays an important role in the process of neuronal degeneration after trauma or focal ischemia (for reviews, see refs. 1 and 2). Glutamate, a neurotransmitter that mediates normal excitatory synaptic transmission by interaction with postsynaptic receptors, is neurotoxic when present in excessive amounts. Injured neurons release massive amounts of glutamate, which induce neuronal cell death by continuous overexcitation of postsynaptic receptors. In this way, the initial trauma is amplified and causes the damage to spread to neighboring cells. Under normal conditions, the synaptically released glutamate is taken up into glial cells, where it is converted into glutamine by the glia-specific enzyme glutamine synthetase [GS; L-glutamate:ammonia ligase (ADPforming); EC 6.3.1.2]; glutamine reenters the neurons and is hydrolyzed by glutaminase to form glutamate, thus replenishing the neurotransmitter pool (3, 4). This biochemical pathway fails, however, to prevent glutamate neurotoxicity after insult. We hypothesized that GS is a limiting factor in this process and that its level in glial cells is not high enough to catalyze the excessive amounts of glutamate released by damaged cells. If this is the case, an increase in GS expression should have neuroprotective benefits.To examine the neuroprotective potential of GS, it is necessary to employ an experimental system in which expression of GS can be modulated. The ...

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“…However, there is now compelling evidence in a number of neuronal cell types, including CGC, that apoptosis as well as necrosis underlie the death of neurones after an excitotoxin exposure (Kure et al, 1991;Heron et al, 1993;Linnik et al, 1993;MacManus et al, 1993MacManus et al, , 1994Ankarcrona et al, 1995; FIG. 8.…”

Section: Figmentioning

confidence: 99%

The Dietary Excitotoxins β‐N‐Methylamino‐l‐Alanine and β‐N‐Oxalylamino‐l‐Alanine Induce Necrotic‐ and Apoptotic‐Like Death of Rat Cerebellar Granule Cells

Staton

Bristow

1997

Journal of Neurochemistry

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Abstract:The neurotoxic properties of the dietary excitotoxins /3-N-methylamino-L-alanine and~3-N-oxalylamino-L-alanine have been studied in rat cerebellar granule cells and compared with those of glutamate. Glutamate caused dose-dependent death of cerebellar granule cells after a 30-min exposure when viability was assessed 24 h later. ß-N-Methylamino-L-alanine and /3-N-oxalylamino-L-alanine, however, were toxic only after 24 or 48 h of exposure. The neurotoxic effects of ß-N-methylaminO-L-alanine were blocked by D(-)-2-amino-5-phosphonopentanoic acid, and those of ß-N-oxalylamino-Lalanine were blocked by kynurenic acid, which demonstrated that these excitotoxins caused cerebellar granule cell death through the activation of glutamate receptors.

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Glutamate triggers internucleosomal DNA cleavage in neuronal cells

Cited by 275 publications

References 21 publications

Mechanisms of Cell Death Induced by the Mitochondrial Toxin 3-Nitropropionic Acid: Acute Excitotoxic Necrosis and Delayed Apoptosis

Mechanisms of Cell Death Induced by the Mitochondrial Toxin 3-Nitropropionic Acid: Acute Excitotoxic Necrosis and Delayed Apoptosis

Glutamine synthetase protects against neuronal degeneration in injured retinal tissue

The Dietary Excitotoxins β‐N‐Methylamino‐l‐Alanine and β‐N‐Oxalylamino‐l‐Alanine Induce Necrotic‐ and Apoptotic‐Like Death of Rat Cerebellar Granule Cells

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