Nipple attachment behavior in rat pups exposed to alcohol in utero.

Two experiments were conducted to further characterize impaired nipple attachment behavior in 5-day-old rat pups exposed to alcohol prenatally. In Experiment 1, animals were given two different nipple attachment tests. In the pups-on-mother test, which required animals to first locate a nipple, alcohol-exposed pups displayed longer attachment latencies than controls. Furthermore, more than 50% of these pups failed to attach during testing. In the pups-on-nipple test, in which no search for the nipple was necessary, prenatal alcohol did not reliably affect attachment. To assess the extent to which alcohol-exposed pups utilize an olfactory cue for attachment, in Experiment 2, nipple attachment was observed using the pups-on-nipple test before and after olfactory cue removal. Similar to controls, the alcohol-exposed animals only attached to the normally scented nipples. Therefore, prenatal alcohol exposure impaired nipple search performance in young rats, but not attachment once at the nipple. Moreover, these pups performed like controls in response to olfactory cue manipulation. Possible mechanisms for the poor search behavior are discussed.