Mechanisms of cell death in primary cortical neurons and PC12 cells

Increasing evidence suggests that the regulation of neuronal cell death is complex. In this study we compared the neurotoxic effects of tumor necrosis factor-alpha (TNF alpha), nitric oxide, and thrombin on primary rat cortic al cell cultures and the neuronal PC12 cell line. Release of lactate dehydr ogenase (LDH) and the intracellular accumulation of nucleosomes were used a s indicators of necrosis and apoptosis, respectively. There was significant LDH release in both neuronal cell types, however, the pattern of LDH relea se was variable and agonist-dependent. In response to the nitric oxide gene rator, sodium nitroprusside (SNP), cortical cells exhibited pronounced LDH release and dramatic morphologic changes, whereas in differentiated PC12 ce lls, TNFa evoked release of LDH with no associated morphologic changes. Bot h neuronal cell types, but not undifferentiated PC12 cells, responded to TN Fa and thrombin with increased apoptosis. Caspase inhibition, but not antio xidant treatment, reduced nucleosome accumulation in primary cortical cells , but not in differentiated PC12 cells. In the differentiated PC12 cells, c aspase inhibition reduced TNF alpha -mediated LDH release, but not nucleoso me accumulation. These data suggest mechanisms involved in neuronal cell de ath utilize multiple pathways that vary depending on the neurotoxic insult and are also influenced by subtle differences among neuronal cell phenotype s. (C) 2001 Wiley-Liss, Inc.