Staurosporine-induced neuronal death: multiple mechanisms and methodological implications

To examine whether multiple pathways of cell death exist in sympathetic neurons, we studied the cell death pathway induced by staurosporine (STS) in sympathetic neurons and compared it with the well-characterized NGF deprivation-induced death pathway. Increasing concentrations of STS were found to induce sympathetic neuronal death with different biochemical and morphological characteristics. One hundred nM STS induced metabolic changes, loss of cytochrome c, and caspase-dependent morphological degeneration which closely resembled the apoptotic death induced by NGF deprivation. In contrast, sympathetic neurons treated with 1 microM STS showed no loss of cytochrome c but exhibited extensive, caspase-independent, chromatin changes that were not TUNEL positive. One microM STS-treated sympathetic neurons had greatly reduced metabolic activities and became committed to die rapidly, yet maintained soma structure and appeared viable by other criteria even up to 48 h after STS treatment, illustrating the need to assess cell death by multiple criteria. Lastly, in contrast to the cell death-inducing activities of 100 nM STS or 1 microM STS, very low concentrations of STS (1 nM STS) inhibited sympathetic neuronal death by acting either at or prior to c-jun phosphorylation in the NGF deprivation-induced PCD pathway.