Effects of various serotonergic agents on alcohol intake and alcohol preference in Wistar rats selected at two different levels of alcohol preference.

Wistar rats can develop a high preference for 3% alcohol after a period of forced alcohol exposure and 2 days of alcohol withdrawal. If these rats are selected at a medium (> or = 60%) and a high (> or = 85%) level of alcohol preference, it is possible to study the effects of various compounds on alcohol intake and alcohol preference in rats with two different levels of alcohol preference. With this procedure, it was demonstrated that the benzodiazepine chlordiazepoxide can reduce alcohol preference at doses > or = 10.0 mg/kg in the high alcohol preference group, by increasing the water consumption without affecting alcohol drinking. Chlordiazepoxide had no effects in the medium alcohol preference group. The 5-HT uptake inhibitors fluoxetine and citalopram reduced alcohol intake and alcohol preference in both the medium and the high alcohol preference groups by means of a reduction in consummatory behaviour. Both drugs clearly affected total fluid intake and body weight gain. The 5-HT1A agent buspirone reduced alcohol intake and alcohol preference in the group of medium alcohol preferring rats at doses between 0.0025 and 0.63 mg/kg. The drug did not change water drinking so that total fluid consumption diminished. At doses > or = 2.5 mg/kg buspirone, there was an increased alcohol consumption. Buspirone was without important effects on the high alcohol preferring rats. The 5-HT3 antagonist ondansetron reduced alcohol intake in both the medium and high alcohol preferring rats at doses between 0.01 and 0.16 mg/kg. The drug had no effects on alcohol preference and water consumption. At some doses, there was a reduction in total fluid intake. The 5-HT2/1C antagonist ritanserin reduced alcohol intake and alcohol preference at doses between 0.04 and 2.50, and 0.16 and 10.0 mg/kg in the medium and high alcohol preferring rats, respectively. Together with the decrease in alcohol consumption there was an increase in water drinking, leaving total fluid intake unaffected. The activity of ritanserin was less pronounced in the high as compared to the medium alcohol preference group. These results indicate that various serotonergic agents can affect alcohol intake and alcohol preference by different mechanisms of action.