Inhibition of GSK-3beta Signaling Pathway Rescues Ketamine-Induced Neurotoxicity in Neural Stem Cell-Derived Neurons

Clinical application of anesthetic reagent, ketamine (Keta), may induce irreversible neurotoxicity in central nervous system. In this work, we utilized an in vitro model of neural stem cells-derived neurons (nSCNs) to evaluate the role of GSK-3 signaling pathway in Keta-induced neurotoxicity. Embryonic mouse-brain neural stem cells were differentiated into neurons in vitro. Keta (50 mu M)-induced neurotoxicity in cultured nSCNs was monitored by apoptosis, immunohistochemical and western blot assays, respectively. GSK-3 signaling pathways, including GSK-3 alpha and GSK-3 beta, were inhibited by siRNA in the culture. The subsequent effects of GSK-3 alpha or GSK-3 beta downregulation on Keta-induced neurotoxicity, including apoptosis and neurite loss, were then evaluated in nSCNs. Finally, caspase and Akt/ERK signal pathways were further examined by western blot to evaluate the regulatory effect of GSK-3 signaling pathways on Keta-induced neural injury. Keta (50 mu M) caused markedly nSCN apoptosis and neurite degeneration in vitro. Keta decreased GSK-3 beta phosphorylation, but had no effect on GSK-3 alpha phosphorylation. SiRNA-induced GSK-3 beta downregulation rescued Keta-induced neurotoxicity in nSCNs by reducing neuronal apoptosis and preventing neurite degeneration. On the other hand, GSK-3 alpha downregulation had no effect on Keta-induced neurotoxicity. Western blot showed that, in Keta-injured nSCNs, GSK-3 beta downregulation reduced Caspase-1/3 proteins, but left phosphorylated Akt/ERK unchanged. GSK-3 beta, not GSK-3 alpha, was specifically involved in the process of Keta-induced neurotoxicity in nSCNs. Inhibiting GSK-3 beta may be an effective approach to counter toxic effect of ketamine on central neurons in clinical and experimental applications.