Involvement of catecholamines in acute tolerance to ethanol in mice.

The percentage of mice able to remain on a rolling drum for 45 s was recorded at 1.25 min and 30 min after administration of ethanol (2.4 g/kg). Though there was no significant difference in brain ethanol levels at the two test times, performance was markedly different with significantly fewer mice able to remain on the drum at 1.25 min than at 30 min. This phenomenon, known as acute tolerance, was antagonised by pretreating mice with haloperidol (0.4 mg/kg), FLA-63 (25 mg/kg), diethyldithiocarbamate (400 mg/kg), phenoxybenzamine (40 mg/kg), phentolamine (20 mg/kg), yohimbine (3 mg/kg) and clozapine (1 mg/kg), but not by spiperone (0.16 mg/kg), alpha-methyl-p-tyrosine (300 mg/kg) or phenobarbitone (10 mg/kg). The relative potencies of the effective blocking agents suggest that alpha 2-receptors may play an important role in mediating acute ethanol tolerance.