Excitotoxin-induced destruction of striatal neurons, proposed as a model of Huntington's disease, involves a process having the biochemical stigmata of apoptosis. Recent studies suggested that transcription factor nuclear factor (NF)-kappa B may be involved in excitotoxicity. To further analyze the contribution of NF kappa B to excitotoxic neuronal death in vivo, changes in binding activities of NF kappa B and other transcription factors as well as the consequences of inhibiting NF kappa B nuclear translocation were measured after the infusion of quinolinic acid (120 nmol) into rat striatum. Internucleosomal DNA fragmentation and terminal transferase-mediated dUTP digoxigenin nick end labeling-positive nuclei appeared 12 hr later and intensified over the next 12 hr. NF kappa B binding activity increased several-fold from 2 to 12 hr, then gradually declined during the next 12 hr. Other transcription factor changes included AP-1, whose binding peaked about 6 hr after quinolinic acid administration, and E2F-1, which was only modestly and transiently elevated. In contrast, quinolinic acid lead to a reduction in OCT-1, beginning after 12 hr, and briefly in SP-1 binding. The NF kappa B, AP-1, and OCT-1 changes were attenuated both by the N-methyl-D-aspartate receptor antagonist MK-801 and the protein synthesis inhibitor cycloheximide. Moreover, quinolinic acid-induced internucleosomal DNA fragmentation and striatal cell death were significantly reduced by the intrastriatal administration of NF kappa B SN50, a cell-permeable recombinant peptide that blocks NF kappa B nuclear translocation. These results illustrate the complex temporal pattern of transcription factor change attending the apoptotic destruction produced in rat striatum by quinolinic acid. They further suggest that NF kappa B activation contributes to the excitotoxin-induced death of striatal neurons.
Animals Apoptosis