In-vitro effects of hyperglycemia on survival of neuroblastoma (SHSY) cells

Objective

It has long been known that chronic hyperglycemia results in severe neurological sequellae. Tight-regulated glycemia has recently proven to ameliorate intensive care outcome and to prevent polyneuropathy. However, direct toxicity of glucose on neurons is hardly investigated

Methods

Cultured neuroblastoma cells (with stauroporine for differentiation) were incubated with different amounts of glucose, starting from a concentration of 30 mM. Cultures were pretreated with placebo, nerve growth factor (NGF) or insulin-like growth factor-I (IGF-I). Survival was measured by the luminescent cell viability assay and the mitochondrial membrane potential (MMP) was measured using JC-1 fluoroscopy.

Results

Differentiated SHSY cells died in 150 mM glucose over the 3-day period measured. Doses of mannitol to obtain comparable osmolality with the different glucose concentrations used resulted in a significant lower cellular mortality. MMP started to decrease at day 1 from 125 mM glucose. Cellular survival, measured at 1–3 days, was positively influenced by adding IGF-I (0.01–100 ng/ml) to the 200 and 300 mM glucose medium. NGF (same doses) also improved survival but was less potent, especially in the higher ranges of glucose. NGF, but not IGF-I, attenuated the MMP decrease elicited by high glucose concentrations.

Conclusion

Neuroblastoma cell death is dose-dependently influenced by increasing doses of glucose. The decreased cellular production of ATP, as measured by MMP, possibly participates in cell death. Neuronal growth factors were able to improve cell survival, but their effects on MMP differ. The clinical relevance of these findings needs further investigation.