Ceramide-induced cell death in primary neuronal cultures: upregulation of ceramide levels during neuronal apoptosis.

Ceramide is a sphingolipid that has been implicated both in apoptosis and protection from cell death. We show that in both rat cerebellar granule cells and cortical neuronal cultures application of C(2)-ceramide causes cell death in a dose- and time-dependent manner. Similar effects were observed with the exogenous application of bacterial sphingomyelinase, which hydrolyzes sphingomyelin located on the outer leaflet of the plasma membrane and leads to endogenous ceramide accumulation. Furthermore, endogenous ceramide levels were increased during apoptosis induced by nutrient deprivation or etoposide treatment. These findings suggest that upregulation of ceramide levels, which may be generated through activation of sphingomyelinase, contributes to neuronal apoptosis.