Role of soluble ceruloplasmin in iron uptake by midbrain and hippocampus neurons.
Ceruloplasmin (CP) is essential for brain iron homeostasis. However, its precise function in brain iron transport has not been definitely determined. In this study, we investigated the effects of soluble CP on iron influx and efflux in primary neuronal culture from the midbrain (the substantia nigra and striatum) and the hippocampus. Our data showed that low concentrations of CP (2, 4, 8 microg/ml) can promote iron influx into iron-deficient neurons, but not the neurons with normal iron status. The same concentrations of CP had no effect on iron efflux from iron-sufficient and normal-iron neurons. Contrary to our expectation, we did not find any regional difference in the effects of CP on iron influx as well as efflux in neurons. The changes in quenching (iron influx) and also dequenching (iron efflux) of intracellular fluorescence, induced by the addition of CP with iron, in the midbrain neurons were no different from those in the hippocampus neurons. The data showed that soluble CP has a role in iron uptake by iron-deficient brain neurons under our experimental conditions. The physiological significance of the results forms the focus for future work.