Chronic exposure to alcohol alters network activity and morphology of cultured hippocampal neurons

•Chronic ethanol suppresses network activity in cultured hippocampal neurons.•This suppression is lifted by blockade of inhibitory synaptic activity.•Chronic exposure to ethanol reduces the number of dendritic spines.•Ethanol suppress network activity by reducing excitation and increasing inhibition.

The effects of chronic exposure to moderate concentrations of ethanol were studied in cultured hippocampal neurons. Network activity, assessed by imaging of [Ca2+]i variations, was markedly suppressed following 5 days of exposure to 0.25-1% ethanol. The reduced activity was sustained following extensive washout of ethanol, but the activity recovered by blockade of inhibition with bicuculline. This reduction of network activity was associated with a reduction in rates of mEPSCs, but not in a change in inhibitory synaptic activity. Chronic exposure to ethanol caused a significant reduction in the density of mature dendritic spines, without an effect on dendritic length or arborization. These results indicate that chronic exposure to ethanol causes a reduction in excitatory network drive in hippocampal neurons adding another dimension to the chronic effects of alcohol abuse.