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Cyanide‐Induced Apoptosis and Oxidative Stress in Differentiated PC12 Cells
Author(s) -
Mills Edward M.,
Gunasekar Palur G.,
Pavlakovic Goran,
Isom Gary E.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.67031039.x
Subject(s) - oxidative stress , apoptosis , cyanide , microbiology and biotechnology , oxidative phosphorylation , chemistry , reactive oxygen species , biochemistry , biology , inorganic chemistry
Terminally differentiated PC12 cells are a useful neuron‐like model for studying programmed cell death in response to nerve growth factor (NGF) deprivation. This in vitro model was used to investigate the mechanism by which cyanide‐induced histotoxic hypoxia produces neuronal degeneration. Treatment of undifferentiated PC12 cells with 0.1 m M KCN for 24 h did not produce cell death. In contrast, treatment of differentiated PC12 cell cultures with 0.1 m M KCN for 24 h increased cell death by 43% when compared with control cultures, as measured by trypan blue dye exclusion and lactate dehydrogenase release assays. The Ca 2+ /Mg 2+ ‐dependent endonuclease inhibitor aurintricarboxylic acid and the transcriptional inhibitor actinomycin D partially attenuated hypoxic toxicity, suggesting roles for endonuclease activation and transcription in this model of neuronal death. Extracted DNA from cyanide‐treated neurons demonstrated cleavage into oligonucleosomal fragments on gel electrophoresis. Transmission electron microscopic analysis showed morphological changes consistent with apoptotic cell death, including membrane blebbing and convolution, as well as chromatin condensation and margination to the nuclear membrane. Addition of either ascorbate or catalase to the cultures partially attenuated the loss of cell viability induced by cyanide, and decreased the incidence of apoptotic cells after treatment, based on the in situ detection of DNA strand breaks. The ability of cyanide to elevate intracellular oxidant species was determined by microfluorescence in differentiated PC12 cells loaded with the oxidant‐sensitive dye 2′,7′‐dichlorofluorescin. Exposure of cells to 0.1 m M KCN produced a rapid generation of oxidants that was blocked ∼50% by ascorbate or catalase. These observations indicate that cyanide induces apoptosis in terminally differentiated, and not undifferentiated, PC12 cells, and that antioxidants significantly reduce the incidence of cyanide‐induced apoptosis.