Volatile Anesthetics May Not Induce Significant Toxicity to Human Neuron-Like Cells

BACKGROUND: In vitro experiments and in vivo animal studies suggest detrimental effects of volatile anesthetics including isoflurane on brain cells. It is not clear whether volatile anesthetics can cause human brain cell injury. METHODS: The SH-SY5Y cells, a human neuroblastoma cell line, were induced to differentiate into terminal neuron-like cells. These differentiated cells and the HCN-2 cells, a human cortical neuronal cell line, were exposed to 2% to 5% isoflurane, 6% sevoflurane, or 12% desflurane for 48 hours at 37°C. Lactate dehydrogenase (LDH) release and the expression of caspase 3, synaptophysin, and drebrin were then measured. RESULTS: Exposure of the differentiated SH-SY5Y and HCN-2 cells to 2% to 4% isoflurane did not increase LDH release and the expression of caspase 3 whose activation leads to apoptosis. The expression of synaptophysin, a synaptic protein, and drebrin, a dendritic spine protein, in the differentiated SH-SY5Ycells was also not affected by 2% to 4% isoflurane. Exposure to 6% sevoflurane or 12% desflurane did not affect LDH release from differentiated SH-SY5Y cells. However, 5% isoflurane significantly increased LDH release from those cells. CONCLUSIONS: Our results suggest that volatile anesthetics at clinically relevant concentrations do not cause human neuron-like cell injury. Isoflurane also may not alter the quantity of dendritic spines and synapses in these human cells.