title: Significant long-term, but not short-term, hippocampal-dependent memory impairment in adult rats exposed to alcohol in early postnatal life.
abstract: In rodents, ethanol exposure in early postnatal life is known to induce structural and functional impairments throughout the brain, including the hippocampus. Herein, rat pups were administered one of three ethanol doses over postnatal days (PD) 4-9, a period of brain development comparable to the third trimester of human pregnancy. As adults, control and ethanol rats were trained and tested in a variant of hippocampal-dependent one-trial context fear conditioning. In Experiment 1, subjects were placed into a novel context and presented with an immediate footshock (i.e., within ∼8 sec). When re-exposed to the same context 24 hr later low levels of conditioned freezing were observed. Context pre-exposure 24 hr prior to the immediate shock reversed the deficit in sham-intubated and unintubated control rats, enhancing freezing behavior during the context retention test. Even with context pre-exposure, however, significant dose-dependent reductions in contextual freezing were seen in ethanol rats. In Experiment 2, the interval between context pre-exposure and the immediate shock was shortened to 2 hr, in addition to the standard 24 hr. Ethanol rats trained with the 2 hr, but not 24 hr, interval displayed retention test freezing levels roughly equal to controls. Results suggest the ethanol rats can encode a short-term context memory and associate it with the aversive footshock 2 hr later. In the 24 hr ethanol rats the short-term context memory is poorly transferred or consolidated into long-term memory, we propose, impeding the memory's subsequent retrieval and association with shock.
authors.affiliation: Department of Psychology, The Ohio State University, Columbus, OH, 43210.
authors.forename: Molly J
authors.initials: MJ
authors.lastname: Goodfellow
authors.forename: Derick H
authors.initials: DH
authors.lastname: Lindquist
mesh_terms: D000818:Animals; D001245:Association Learning / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D004597:Electroshock; D000431:Ethanol / Q000494:pharmacology*; D005239:Fear / Q000187:drug effects; D005260:Female; D046352:Freezing Reaction, Cataleptic; D006624:Hippocampus / Q000187:drug effects*; D008297:Male; D057567:Memory, Long-Term / Q000187:drug effects*; D008570:Memory, Short-Term / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D000431:Ethanol
keywords: NMDA receptor; context pre-exposure facilitation effect; fetal alcohol spectrum disorder; hippocampus; memory consolidation