Cyanide-induced apoptosis involves oxidative-stress-activated NF-kappaB in cortical neurons.Toxicol Appl Pharmacol. 2000 Apr 15; 164(2):196-205.TA
The central nervous system is one of the main target organs in cyanide toxicity. Primary cultured cortical neurons were used to study the cellular mechanisms underlying cyanide-induced cytotoxicity. After exposure to KCN (100-300 microM) for 24 h, cortical neurons underwent apoptosis as characterized by positive TUNEL staining. Reactive oxygen species (ROS) play an important role in cyanide-induced neuronal apoptosis; immediately after cyanide (100-300 microM) treatment, ROS generation was observed and continued to be elevated for up to 3 h. NMDA receptor activation and subsequent Ca(2+) influx contribute in part to cyanide-induced ROS formation, since the selective NMDA receptor antagonist MK801 and intracellular Ca(2+) chelator BAPTA blocked ROS generation. Interestingly, caspases, recently reported to be involved in neuronal apoptosis, play a role in the late phase of ROS production after cyanide stimulation. Z-VAD, a nonspecific caspase inhibitor, blocked ROS generated 1 h after cyanide treatment, but it had no effect on ROS generated immediately after cyanide treatment. Nuclear factor kappaB (NF-kappaB), a redox-sensitive transcription factor, was activated dose dependently after cyanide treatment. Blockade of ROS generation by MK801, Z-VAD, and various antioxidants also blocked the activation of NF-kappaB. SN50, a synthetic peptide which inhibits the nuclear translocation of NF-kappaB, blocked cyanide-induced apoptotic cell death. These results indicate that NF-kappaB plays an important role in cyanide-induced apoptosis in cortical neurons, and the caspases may contribute in part to the activation of NF-kappaB after cyanide treatment by inducing the late phase of ROS generation.