Early ethanol exposure in mice increases laterality of rotational side preference in the free-swimming test

In order to test the hypothesis that early postnatal ethanol exposure has long lasting behavioral effects that include changes to the normal pattern of cerebral asymmetries, the free swimming test (FST) was used to study the behavior of adult Swiss mice (males and females) exposed to ethanol during the third trimester equivalent of human gestation. Animals received ethanol (5 g/Kg ip, ETOH group) or saline (CONT group) on alternate days from postnatal day (P) 2 to P8, and were submitted to 1 session of open field (OF) and 3 sessions of FST from P75 to P81. No differences between ETOH and CONT groups were observed in OF. However, the FST revealed significant differences between ETOH and CONT mice during the first session. The percentage of animals that presented strong turning preferences (especially to the right side) was higher in the ETOH group when compared with the CONT group. These data give support to the hypothesis that early ethanol exposure affects cerebral asymmetries and suggests that the FST is a useful tool to investigate the long-lasting effects of ethanol exposure during development.