Abstract:Objective To explore the effect of bilirubin on intracellular Ca 2+ of cerebral cortex neurons and the therapeutic effect of MgSO 4. Methods Cerebral cortical neurons were cultured from the embryonic rat brain. The free cytosolic Ca 2+ concentration ([Ca 2+ ]i) of the cultured neurons was determined with a fluorescent Ca 2+ chelator (Fura-2) after exposure of the neurons to different concentrations of bilirubin. Results Immature neurons (neurons cultured for only 2 days) responded within 4 hours to 100 mmol bilirubin by an increase in [Ca 2+ ]i from 75.3 nmol to 320.8 nmol, an increase that during another 4 hours of exposure reached to 400.7 nmol. This increase in [Ca 2+ ]i could not be reversed by the removal of bilirubin. In contrast to these findings, mature neurons (8 days in culture) exhibited only a small increase (from 70.6 nmol to 150.8 nmol) in [Ca 2+ ]i within 4 hours after the exposure to 100 mmol bilirubin, and this rapid increase in [Ca 2+ ]i tended to decline on the following prolonged 4 hour exposure to bilirubin. Moreover, after the removal of bilirubin, the increase in [Ca 2+ ]i was partially reversible. The N-methyl-D-aspartate (NMDA) receptor antagonists MgSO 4 could significantly block the response. Conclusions Bilirubin can induce an increase in intracellular Ca 2+ in primary cultured cerebral cortex neurons and the change can be partially reversed by NMDA receptor antagonists MgSO 4.
