Blockade of glutamate receptors unmasks neuronal apoptosis after oxygen-glucose deprivation in vitro

Gwag, Byoung Joo; Lobner, Doug; Koh, Jae‐Young; Wie, Myung‐Bok; Choi, Dennis W.

doi:10.1016/0306-4522(95)00232-8

Cited by 244 publications

(157 citation statements)

References 31 publications

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“…Our data support an emerging theory proposed by Choi (1995) that apoptotic and necrotic mechanisms may coexist within individual degenerating neurons after metabolic insults, and that the former may be masked by a rapid excitotoxic necrosis (Gwag et al, 1995). This is particularly relevant to conditions in which there are both metabolic impairment and an elevation in extracellular Figure 6.…”

Section: Discussionsupporting

confidence: 88%

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: Discussionsupporting

confidence: 88%

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

1997

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“…Indeed, the combination of NRG-1 and MK-801 provided enhanced neuroprotective compared to either compound alone as observed in both in vivo and in vitro studies. Blocking NMDA receptors in OGD has been shown to prevent glutamate-mediated excitotoxic, necrotic neuronal death, resulting in a shift from necrotic death to an apoptotic form of cell death in neuronal cultures [18]. This may therefore increase the effectiveness of NRG-1 by switching neurons to an apoptotic fate.…”

Section: Discussionmentioning

confidence: 99%

Neuroprotection by neuregulin-1 in a rat model of permanent focal cerebral ischemia

Ford

et al. 2007

Brain Research

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Neuregulin-1 (NRG-1) is a growth factor with potent neuroprotective capacity in ischemic stroke. We recently showed that NRG-1 reduced neuronal death following transient middle cerebral artery occlusion (tMCAO) by up to 90% with an extended therapeutic window. Here, we examined the neuroprotective potential of NRG-1 using a permanent MCAO ischemia (pMCAO) rat model. NRG-1 reduced infarction in pMCAO by 50% when administered prior to ischemia. We previously demonstrated using gene expression profiling that pMCAO was associated with an exaggerated excitotoxicity response compared to tMCAO. Therefore, we examined whether co-treatment with an inhibitor of excitotoxicity would augment the effect of NRG-1 following pMCAO. Both NRG-1 and the N-methyl-D-aspartate (NMDA) antagonist MK-801 similarly reduced infarct size following pMCAO. However, combination treatment with both NRG-1 and MK-801 resulted in greater neuroprotection that either compound alone, including a 75% reduction in cortical infarction compared to control. Consistent with these findings, NRG-1 reduced neuronal death using an in vitro ischemia model and this effect was augmented by MK-801. These results demonstrate the efficacy of NRG-1 in pMCAO rat focal ischemia model. Our findings further indicate the potential clinically relevance of NRG-1 alone or as a combination strategy for treating ischemic stroke.

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“…4A). Recently, others have reported evidence of apoptosis in cultured neurons challenged with excitotoxins (Bonfoco et al, 1995) and hypoxia-hypoglycemia (Gwag et a!., 1995;Gottron et al, 1997), based on morphological criteria or the presence of DNA laddering. Because we used a biochemical marker that earmarks an apoptosis-linked event (caspase activation), our evidence is more compelling and unequivocal.…”

Section: Discussionmentioning

confidence: 99%

Evidence for Activation of Caspase‐3‐Like Protease in Excitotoxin‐ and Hypoxia/Hypoglycemia‐Injured Neurons

Nath¹,

Probert²,

McGinnis

et al. 1998

Journal of Neurochemistry

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Caspase activation has been shown to be a critical step in several models of neuronal apoptosis such as staurosporine treatment of human neuroblastoma SH-SY5Y cells and potassium deprivation of rat cerebellar granule neurons. One common event is the appearance of caspase-mediated 1 20-kDa nonerythroid ea-spectrin breakdown product (SBDP1 20). Second, inhibitors of the caspase family are effective blockers of such neuronal death. In this study, we report the appearance of caspase-mediated SBDP1 20 in excitotoxin-challenged fetal rat cerebrocortical neurons [N-methyl-o-aspartate (NMDA), a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate] and rat cerebellar granule neurons (NMDA and kainate). A general caspase inhibitor, carbobenzoxy-Asp-CH 2OC (0) -2 ,6-dichlorobenzene (Z-D-DCB), blocked the formation of SBDP1 20 under these conditions and attenuated the observed NMDA-induced lactate dehydrogenase (LDH) release in both cell types. Furthermore, hydrolytic activity toward a caspase-3-preferred synthetic peptide substrate, acetyl-DEVD-7-amido-4-methylcoumarin, was significantly elevated in NM DA-treated granule neurons. Lastly, oxygen-glucose deprivation (OGD) -challenged cerebrocortical cultures also showed the appearance of SBDP12O. Again, Z-D-DCB blocked the SBDP12O formation as well as attenuated the LDH release from the OGD-challenged neurons. Taken together, the presence of caspase-specific SBDP1 20 and the neuroprotective effects of Z-D-DCB strongly suggest that caspase activation contributes at least in part to excitotoxin-and OGD-induced neuronal death.

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Blockade of glutamate receptors unmasks neuronal apoptosis after oxygen-glucose deprivation in vitro

Cited by 244 publications

References 31 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

Neuroprotection by neuregulin-1 in a rat model of permanent focal cerebral ischemia

Evidence for Activation of Caspase‐3‐Like Protease in Excitotoxin‐ and Hypoxia/Hypoglycemia‐Injured Neurons

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