Prenatal ethanol exposure impairs passive avoidance acquisition and enhances unconditioned freezing in rat offspring

Previous studies have suggested that ethanol exposure during brain development affects responses to fear and anxiety after maturity. To clarify in detail the impaired behavior related to fear and anxiety seen in rat offspring prenatally exposed to ethanol, their behaviors were observed using an elevated T-maze (ETM) test, which allows assessment of passive avoidance acquisition and one-way escape separately, and an elevated open platform (EOP) test for the assessment of unconditioned freezing against innate fear. The ETM test revealed that acquisition of passive avoidance was significantly inhibited in prenatally ethanol-exposed rats, while their escape behavior was not altered. In the EOP test, the duration of the freezing behavior was significantly elongated in prenatally ethanol-exposed offspring. Thus, we concluded that prenatal ethanol exposure could impair acquisition of passive avoidance, while it could facilitate a response related to unconditioned fears in rat offspring.

► Prenatally ethanol-exposed rats were examined for behavioral responses to fear stimuli.
► Elevated T-maze and elevated open platform tests was used for the assessments.
► The acquisition of passive avoidance was impaired in the ethanol-exposed rats.
► The response to unconditioned fear was facilitated in the ethanol-exposed rats.