Taurine-evoked chloride current and its potentiation by intracellular Ca2+ in immature rat hippocampal CA1 neurons

Taurine is one of the most abundant free amino acids in the immature mammalian central nervous system. In the present study, whole-cell patch-clamp recordings were made to examine taurine-evoked currents (I-Tau) in acutely dissociated immature rat hippocampal CA1 neurons. Taurine at low concentrations (less than or equal to1 mM) activated glycine receptors while at high concentrations (greater than or equal to3 mM) activated both glycine and GABA(A) receptors. Moreover, elevation of intracellular Ca2+ via non-NMDA receptor activation enhanced I-Tau reversibly. The results indicate that taurine may act as a native ligand of glycine receptors and modulate neurotransmissions in the immature hippocampus, and under certain conditions it can also activate GABA(A) receptors. The potentiation of I-Tau by intracellular Ca2+ may contribute to the protection effect of taurine under some cell-damaging conditions.