Picrotoxin increased acetylcholine release from rat cultured embryonic septal neurons

GABA is a major inhibitory neurotransmitter in the mature mammalian brain. In the early stages of brain development, it has been reported that GABA _A receptor stimulation and the associated increase in Cl^- conductance lead to membrane depolarization. In this study, we tested the effects of picrotoxin, a GABA_A receptor Cl^- channel blocker, on spontaneously released acetylcholine (ACh) from cultured rat embryonic septal cells. Picrotoxin increased spontaneously released ACh. These results indicate that blockade of GABA-activated Cl^- channel increases neuronal excitability even in an early stage of the development.