Objective: To explore the involvement of calcium in the mechanism of hypoxic/hypoglycemic insults and nerve growth factor (NGF) protection.
Methods: Neuron viability and lactate dehydrogenase (LDH) efflux in the bathing medium in cerebral cortex cultures from fetal rats were measured. Calcium fluorescent indicator Fura-2/AM was used to measure the intracellular free calcium ([Ca2+]i).
Results: Massive neuronal death occurred 16-24 h following the onset of hypoxia/hypoglycemia. NGF (3-100 micrograms.L-1) dose-dependently attenuated 24 h hypoxia/hypoglycemia-induced efflux of LDH and elevated the number of surviving neurons. Hypoxia/hypoglycemia induced a reduction in [Ca2+]i in early stage and a large elevation of [Ca2+]i in later period. NGF 50 micrograms.L-1 increased [Ca2+]i to normal limits during the early stages of hypoxia/hypoglycemia and prevented the later elevation in [Ca2+]i.
Conclusion: The [Ca2+]i elevation may be responsible for the cell damage in oxygen/glucose deprived cultures. NGF protects cerebral cortical neurons against hypoxic/hypoglycemic insults via stabilizing [Ca2+]i level or preventing the late rise in [Ca2+]i.