Long-term potentiation in the rat hippocampus is reversibly depressed by chronic intermittent ethanol exposure

Alcohol exposure induces multiple neuroadaptive changes in the CNS that can have serious long-term consequences on CNS function including cognitive effects and attenuation of learning and memory. The cellular mechanisms underlying the CNS effects of alcohol have yet to be fully elucidated and are likely to depend on the pattern and dose of alcohol exposure. Using electrophysiological recordings from hippocampal slices obtained from control and chronic alcohol-treated rats, we have investigated the effects of a binge pattern of alcohol abuse on synaptic plasticity in the CNS. The alcohol-treated animals were exposed to ethanol vapor for 12-14 days using an intermittent exposure paradigm (14 h ethanol exposure/10 h ethanol withdrawal daily; blood alcohol levels similar to180 mg/dl), a paradigm that models human binge alcohol use. Induction of long-term potentiation (LTP) in the CA1 region of the hippocampus by tetanic stimulation of Schaffer collaterals was completely blocked in slices from the chronic alcohol-treated animals. LTP remained blocked 1 day after withdrawal of animals from alcohol, indicating that the neuroadaptive changes produced by alcohol were not readily reversible. Partial recovery was observed after withdrawal from alcohol for 5 days. Other measures of synaptic plasticity including posttetanic potentiation and paired-pulse facilitation were also altered by the intermittent alcohol treatment paradigm. The results suggest that alterations in synaptic plasticity induced by chronic intermittent ethanol consumption play an important role in the effects of binge alcohol use on learning and memory function.