Comparison of acetaldehyde and ethanol: depression of motor activity in mice

The fine and gross motor activity of mice was measured at 1-minute intervals for 15 minutes after intravenous administration of ethanol or acetaldehyde. Acetaldehyde transiently reduced both types of motor activity whereas the effects of ethanol were more prolonged. The 1-minute ED₅₀ values for depression of fine and gross activity by acetaldehyde are 2.2. and 2.7 mg/kg, respectively. The corresponding values for ethanol are 740 and 516 mg/kg. The differences in relative potencies became smaller as the time interval over which activity was measured increased. Thus, the potency of acetaldehyde as a depressant of behavior relative to ethanol is considerably greater than has previously been reported if effects are determined immediately after drug administration.