TLX2 and ischemia: In neonatal rat optic nerve, an important cause of astrocyte cell death is the run-down of Na+–K+ pumps and Na+–K+–Cl− cotransport (NKCC1) during hypoxia/ischemia, which results in a rise in [Na+]i and reversal of the Na+–Ca2+ exchanger (NCX) [52], [53].