Action of GABA on hippocampal neurons

During low frequency stimulation of various neural pathways, intracellular recording from rat hippocampal neurons in situ reveals large IPSPs characterized by a large conductance increase and potential changes that are highly sensitive to the Cl- gradient. GABA (but not glycine) produces comparable increases in conductance as well as potential changes which reverse at about the same level as the IPSPs. Therefore GABA has all the properties of the physiological inhibitory transmitter. IPSPs and the effects of GABA show a pronounced desensitization which could account for the spectacular facilitation of firing that is observed during repetitive action of hippocampal units.