Effects of alpha 2-adrenergic drugs on the alcohol consumption of alcohol-preferring rats.

The effects of seven-day subcutaneous infusion of an alpha 2-adrenoceptor agonist, medetomidine, and an alpha 2-adrenoceptor antagonist, atipamezole, on the voluntary alcohol consumption of alcohol-preferring rats were studied. The drugs were administered by means of implanted osmotic minipumps. Sham-operated control rats had no pumps implanted. The rats had a free choice between 10% alcohol and plain water for 30 days before pump implantation and again for six days starting 24 hr after the operation. Atipamezole increased the alcohol consumption during the first day of free choice. Medetomidine had no significant effect. During the remaining period of infusion, the alcohol consumption did not differ from that preceding the pump implantation in each treatment group. Animals in the atipamezole group gained more weight during the seven-day trial than did those in the medetomidine and control groups. The amine changes in different regions of the brain were consistent with medetomidine decreasing and atipamezole increasing the noradrenaline turnover. The present results indicate that specific drugs acting on the alpha 2-adrenoceptors produce only minor changes in the voluntary alcohol drinking of alcohol-preferring rats.