Effect of low concentrations of ethanol on CA1 hippocampal neurons in vitro

The effects of ethanol (10, 20, 50, and 100 mM) have been studied on field potentials in the CA1 region of the in vitro hippocampal slice preparation. Ethanol produced depression of the orthodromically evoked CA1 population spike and raised the threshold for orthodromic spike production. The effects of ethanol on the size of the population spike were highly correlated with the amount of the inhibition present in the slice as measure by paired pulse stimulation in control medium. Ethanol increased recurrent inhibition in the slice but had no significant effect on the antidromic response and produced only small changes in the dendritic field potential amplitudes. Adaptation or acute tolerance to the depressing effects of ethanol was observed in many slices. It is suggested that ethanol acts by potentiating the intrinsic inhibitory system in the hippocampus.