Intermittent ethanol binge exposure impairs object recognition but spares contextual and tone fear memory in adolescent rats

ABSTRACT

Adolescent brain development seems to be important for the maturation of brain structures and behavior. Intermittent binge ethanol drinking is common among adolescents, and this type of drinking can induce brain damage and cognitive deficits. In addition, emotional changes are frequently seen in alcoholics and rodents treated with ethanol. Considering the close relation between emotional arousal and cognitive responses, the present work investigates if intermittent ethanol binge exposure could differentially alter the performance of adolescent rats in aversive and non-aversive motivated tests. Male adolescent rats were submitted to ethanol treatment (2.5 or 5.0 g/Kg, o.a.) at 48-h intervals over postnatal day (PND) 30 to 60. Control animals were exposed to a similar administration protocol with saline administration. At PND61-PND63 animals were submitted to one-trial object recognition or contextual and tone fear conditioning paradigms. Binge ethanol drinking (at both 2.5 and 5.0 g/Kg) did not change freezing response in the contextual and tone fear conditioning. However, all doses impaired recognition rates 24h after training in object recognition test. In addition, despite a diminution of horizontal locomotion in the open field (only for the 5.0 g/Kg dose), no difference was detected regarding time in immobility, time in grooming and number of rearing in this paradigm. The present results show that the cognitive impairment resulting from intermittent binge ethanol exposure has a negative correlation with learning-associated emotional arousal.