Neurobehavioral profiles during the acute phase of ethanol withdrawal in adolescent and adult Sprague-Dawley rats

Rationale: Adolescent and adult rats show differential sensitivity to many of the effects of ethanol. Objectives: The current studies were designed to further explore differences in the development of ethanol dependence by examining anxiety-like behavior, acoustic startle, prepulse inhibition, and EEG activity during the acute phase of ethanol withdrawal. Methods: Male Sprague-Dawley rats were exposed to ethanol vapor (12 h/day for 14 days) during adolescence or adulthood. Neurobehavioral assessments were performed before exposure began and then during the acute phase of ethanol withdrawal (i.e., 7-10 h after the termination of daily ethanol exposure). Results: Behavior in the light-dark box did not reveal indices of pronounced anxiety-like behavior in ethanol exposed rats from either age group during withdrawal. Acoustic startle magnitude was significantly reduced and prepulse inhibition significantly enhanced in ethanol exposed rats during withdrawal, but these changes were independent of age. Frontal cortical EEG activity was not altered during ethanol withdrawal, but high frequency power in the parietal power EEG (i.e., 16-32 and 32-50 Hz) was selectively increased in ethanol exposed adolescents. Conclusions: The overall indices of ethanol withdrawal observed in these studies were mild. but these data do support the hypothesis that ethanol withdrawal symptoms can differentially develop in adolescent and adult rats. However, sensitivity to ethanol during adolescence can be increased or decreased depending on the symptom being assessed. As a result, it is unclear if more rapid development of ethanol dependence in adolescents is a factor, which facilitates the development of alcoholism. (c) 2006 Elsevier B.V. All rights reserved.