Figure 1. Hc-TeTx induces a moderate but rapid and sustained increase in the ceramide content and in the ceramide/sphingomyelin ratio.

Sphingolipids in cultured granular neurons (CGN) or in NGF-differentiated PC12 were labeled by incubation of the cells with ¹⁴C-serine for 24 h. Subsequently, cultureswere treated with Hc-TeTx 10 nM at the indicated time points, or with TNF (50 ng/mL) for 6 h as a positive control. Radioactivities incorporated in ceramide and sphingomyelin were measured after TLC separation, as indicated in Materials and Methods. Amounts of ceramide after every treatment were determined and expressed in terms of pmols of ceramide/µg of protein (A and C). The ceramide/sphingomyelin ratios were also measured (B and D). Shown are mean ± SD of three independent experiments.