Inhibition of glutamate-induced cell death by sodium nitroprusside is not mediated by nitric oxide

Nitric oxide (NO) is a potent extracellular and intracellular physiological messenger. However, NO liberated in excessive amounts can be involved in macromolecular and mitochondrial damage in brain aging and in neurodegenerative disorders. The molecular mechanism of its neurotoxic action is not fully understood. Our previous data indicated involvement of NO in the release of arachidonic acid (AA), a substrate for cyclo- and lipoxygenases (COX and LOX, respectively). In this study we investigated biochemical processes leading to cell death evoked by an NO donor, sodium nitroprusside (SNP). We found that SNP decreased viability of pheochromocytoma (PC12) cells in a concentration- and time-dependent manner. SNP at 0.1 mM caused a significant increase of apoptosis-inducing factor (AIF) protein level in mitochondria. Under these conditions 80% of PC12 cells survived. The enhancement of mitochondrial AIF level might protect most of PC12 cells against death. However, NO released from 0.5 mM SNP induced massive cell death but had no effect on protein level and localization of AIF and cytochrome c. Caspase-3 activity and poly(ADP-ribose) polymerase-1 (PARP-1) protein levels were not changed. However, PARP activity significantly decreased in a time-dependent manner. Inhibition of both COX isoforms and of 12/15-LOX significantly lowered the SNP-evoked cell death. We conclude that AIF, cytochrome c and caspase-3 are not responsible for the NO-mediated cell death evoked by SNP. The data demonstrate that NO liberated in excess decreases PARP-1 activity. Our results indicate that COX(s) and LOX(s) are involved in PC12 cell death evoked by NO released from its donor, SNP.

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Enhanced release of nitric oxide causes increased cytotoxicity of S-nitroso-N-acetyl-dl-penicillamine and sodium nitroprusside under hypoxic conditions

Biochemical Journal ◽

10.1042/bj3180789 ◽

1996 ◽

Vol 318 (3) ◽

pp. 789-795 ◽

Cited By ~ 38

Author(s):

Iosif IOANNIDIS ◽

Michael BÄTZ ◽

Thomas PAUL ◽

Hans-Gert KORTH ◽

Reiner SUSTMANN ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Cell Death ◽

Cell Viability ◽

Sodium Nitroprusside ◽

Chemical Processes ◽

Hypoxic Conditions ◽

Time Period ◽

Increased Sensitivity ◽

Hypoxic Incubation

S-Nitroso-N-acetyl-dl-penicillamine (SNAP) and sodium nitroprusside (SNP), both of which are known to release nitric oxide (•NO), exhibited cytotoxicity against cultivated endothelial cells. Under hypoxic conditions 5 mM SNAP and 20 mM SNP induced a loss in cell viability of about 90% and 80% respectively, after an 8 h incubation. Under normoxic conditions, cell death was only 45% and 42% respectively within the same time period. Concentrations of •NO liberated from SNAP and SNP were measured by the oxyhaemoglobin method and by two of the recently developed nitric oxide cheletropic traps (NOCTs). The •NO concentrations from SNAP and SNP increased from 74 µM and 28 µM to 136 µM and 66 µM respectively within 15 min of hypoxic incubation, and then decreased to 36 µM and 28 µM. In the respective normoxic incubations the •NO levels from SNAP and SNP remained in the region of about 30 µM and 20 µM respectively. In contrast, spermine/NO adduct (spermineNONOate) was shown to be more toxic under normoxic than under hypoxic conditions. Under either of these conditions, the concentration of •NO liberated from 2 mM spermineNONOate was about 20 µM. The results demonstrate that the cytotoxicity of SNAP and SNP, but not of spermineNONOate, is significantly enhanced under hypoxic compared with normoxic incubations. Studies on the •NO-releasing behaviour of these compounds indicate that the increased toxicity of SNAP and SNP under hypoxic conditions is related to the influence of O2 on the chemical processes by which •NO is produced from the precursors, rather than to an increased sensitivity of the hypoxic cells towards •NO.

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The effect of sodium nitroprusside on survival and stress signaling in PC12 rat phaeochromocytoma cells expressing a dominant negative RasH mutant protein

Biochemistry and Cell Biology ◽

10.1139/bcb-2012-0078 ◽

2013 ◽

Vol 91 (4) ◽

pp. 230-235 ◽

Cited By ~ 2

Author(s):

Judit Bátor ◽

Judit Varga ◽

József Szeberényi

Keyword(s):

Nitric Oxide ◽

Cell Death ◽

Sodium Nitroprusside ◽

Dominant Negative ◽

Translation Initiation Factor ◽

Nitric Oxide Donor ◽

Mutant Protein ◽

Erk Pathway ◽

Ras Proteins ◽

Stimulation Of

Toxic concentrations of the second messenger nitric oxide cause cellular stress leading to cell death. Ras proteins, possible targets of nitric oxide–induced nitrosylation, may act as mediators in nitrosative stress. To analyze the possible involvement of Ras proteins in nitric oxide cytotoxicity, a PC12 rat phaeochromocytoma cell line expressing a dominant negative Ras mutant protein was used in this study. Cytotoxic concentrations of the nitric oxide donor sodium nitroprusside activated several proapoptotic mechanisms, including stimulation of the stress kinase pathways mediated by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), inhibition of the translation initiation factor eIF2α, induction and phosphorylation of the p53 protein, and inhibited Akt-mediated antiapoptotic signaling, independent of Ras function. Simultaneously, Ras-dependent stimulation of the prosurvival ERK pathway was also observed, followed by an increased activation of the caspase-9/caspase-3 cascade in cells with impaired Ras function. It is concluded that nitric oxide stimulation of multiple signaling pathways contributes to the cell death program, whereas concomitant activation of the Ras/ERK pathway provides a certain degree of protection.

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