High Dose C6 Ceramide-Induced Response in Embryonic Hippocampal Cells

Ceramide is a critical molecule in both the physiology and pathology of the central nervous system. The most studied aspect is its effect on embryonic/stem cells. A salient question is whether low doses of ceramide induce neuronal differentiation without interfering with sphingolipid metabolism and whether high doses can be used in glioblastoma for their cytotoxic effect. Here, we examined the effect of a high dose of ceramide (13 µM) on HN9.10e cells. Interestingly, 13 µM ceramide induced an immediate increase in cell viability, followed by an increase in the number of mitochondria. Microscopic and morphometric analysis revealed a decrease in the number of differentiated cells with 13 µM compared to 0.1 µM but with longer neurites. Furthermore, the lipidomic study demonstrated an increase in the formation of medium-long-chain ceramide and sphingomyelin species and sphingosine 1 phosphate. Sphingolipid modification correlated with SMPD3, ASAH2, and SPHK2 gene expression coding for neutral sphingomyenase 2, ceramidase 2, and sphingosine kinase 2, respectively. Overall, our data show that the variety of responses to ceramide of the same cell type is dependent on the concentration used. Low doses do not affect sphingolipid metabolism, and high doses do so with a different cellular response.