Prenatal ethanol exposure impairs temporal ordering behaviours in young adult rats.

Prenatal ethanol exposure (PNEE) causes significant deficits in functional (i.e., synaptic) plasticity in the dentate gyrus (DG) and cornu ammonis (CA) hippocampal sub-regions of young adult male rats. Previous research has shown that in the DG, these deficits are not apparent in age-matched PNEE females. This study aimed to expand these findings and determine if PNEE induces deficits in hippocampal-dependent behaviours in both male and female young adult rats (PND 60). The metric change behavioural test examines DG-dependent deficits by determining whether an animal can detect a metric change between two identical objects. The temporal order behavioural test is thought to rely in part on the CA sub-region of the hippocampus and determines whether an animal will spend more time exploring an object that it has not seen for a larger temporal window as compared to an object that it has seen more recently. Using the liquid diet model of FASD (where 6.6% (v/v) ethanol is provided through a liquid diet consumed ad libitum throughout the entire gestation), we found that PNEE causes a significant impairment in the temporal order task, while no deficits in the DG-dependent metric change task were observed. There were no significant differences between males and females for either task. These results indicate that behaviours relying partially on the CA-region may be more affected by PNEE than those that rely on the DG.