Acute tolerance to the motor impairment effects of ethanol

Abstract

Rats were trained to avoid electric shock by running treadmill-fashion along a moving belt. When the animals were consistently performing at a 95% avoidance level, the effects of saline and 1.5, 2.0, and 2.5 g/kg ethanol on motor performance were assessed in three 2-min trials 23 min following IP administration. Results indicated a strong relationship between plasma alcohol concentration and the mean time off the belt for the three trials. Further, the technique differentiated a dose-dependent impairment in responding. In addition, the results indicated that the motor impairment effects diminished for all dose levels over the 7-min test period. It is unlikely that the improved performance across the three trials is due to changes in metabolism or increased duration of exposure to the drug. The data suggest that the moving belt test is sensitive to practice effects and that a behavioral augmentation to the motor impairment effects of ethanol can occur within several minutes.