Recognition memory is selectively impaired in adult rats exposed to binge-like doses of ethanol during early postnatal life.

Abstract

Exposure to alcohol in utero can induce a variety of physical and mental impairments, collectively known as fetal alcohol spectrum disorders (FASD). This study explores the persistent cognitive consequences of ethanol administration in rat pups over postnatal days (PD) 4-9, modeling human third trimester consumption. Between PD65-70, ethanol-exposed (5E) and control rats were evaluated in two variants of recognition memory, the spontaneous novel object recognition (NOR) task, using 20 and 240min sample-to-test delays, and the associative object-in-context (OIC) task, using a 20min delay. No treatment group differences were observed in object exploration during the sample session for any task. In the 20min NOR test session the 5E rats explored the novel object significantly less than controls, relative to the total time exploring both objects. Postnatal ethanol exposure is hypothesized to impede object memory consolidation in the perirhinal cortex of 5E rats, hindering their ability to discriminate between familiar and novel objects at short delays. The 5E rats performed as well or better than control rats in the 240min NOR and the 20min OIC tasks, indicating developmental ethanol exposure selectively impairs the retention and expression of recognition memories in young adult rats.