Glycolaldehyde (GA) is a highly reactive hydroxyaldehyde and one of the glycolytic metabolites producing advanced glycation endproducts (AGEs), but its toxicity toward neurons and Schwann cells remains unclear. In the present study, we found that GA exhibited more potent toxicity than other AGE precursors (glyceraldehyde, glyoxal, methylglyoxal and 3-deoxyglucosone) against immortalized IFRS1 adult rat Schwann cells and ND7/23 neuroblastoma × neonatal rat dorsal root ganglion (DRG) neuron hybrid cells. GA affected adult rat DRG neurons and ND7/23 cells more severely than GA-derived AGEs, and exhibited concentration- and time-dependent toxicity toward ND7/23 cells (10 < 100 < 250 < 500 µM; 6 h < 24 h). Treatment with 500 µM GA significantly up-regulated the phosphorylation of c-jun N-terminal kinase (JNK) and p-38 mitogen-activated kinase (p-38 MAPK) in ND7/23 cells. Furthermore, GA-induced ND7/23 cell death was significantly inhibited due to co-treatment with 10 µM of the JNK inhibitor SP600125 or the p-38 MAPK inhibitor SB239063. These findings suggest the involvement of JNK and p-38 MAPK-signaling pathways in GA-induced neuronal cell death and that enhanced GA production under diabetic conditions might be involved in the pathogenesis of diabetic neuropathy.
Keywords: Diabetic neuropathy; Glycolytic metabolites; Mitogen-activated protein kinase signaling; Schwann cells; Sensory neurons; Viability.