Actions of GABA in developing rabbit hippocampus: an in vitro study.

The development of neuronal responses to gamma-aminobutyric acid (GABA) was examined using intracellular recording techniques in area CA1 of rabbit hippocampal slices maintained in vitro. Microapplication of GABA (via pressure ejection) in stratum pyramidale in slices from mature rabbits (age 1 month) evoked a hyperpolarization of CA1 pyramidal neurons. The reversal potential (Erev) for this response was approximately -70 mV. In contrast, local application of GABA into stratum pyramidale in slices from immature rabbits (age 7-10 days) produced a depolarizing response with an Erev of approximately -54 mV. The relationship between these findings and the development of inhibitory synaptic activity in rabbit hippocampus is discussed.