Regional effects of ethanol on limbic afterdischarge activity

This study assessed the effects of acute administration of ethanol on afterdischarge (AD) activity evoked by electrical stimulation of the amygdala, septum and hippocampus. Limbic AD thresholds, duration and propagation were determined in cats following intravenous infusions of saline or ethanol (0.4, 0.8 and 1.6 g/kg). Ethanol administrations significantly increased septal and amygdalar, but not hippocampal AD thresholds. This effect was dose-related and most pronounced at the septum. Reductions in AD duration followed ethanol treatment and demonstrated similar regional differences. In addition, projected discharges were reduced, propagation of AD from stimulation sites to limbic and neocortical projections sites were suppressed and ictal episodes were attenuated following ethanol treatment. Afterdischarge activity was affected even by the 0.4 g/kg dose which produced no observable change in behavior. These findings indicate that ethanol reduces the responsiveness of limbic structures to electrical stimulation--suppressing the initiation, maintenance and propagation of limbic afterdischarges. The amygdala, septum and hippocampus proved differentially sensitive to ethanol.