Stimulation of locomotor activity by voluntarily consumed ethanol in Sardinian alcohol-preferring rats

Stimulation of motor activity induced by ethanol has been proposed to reflect the positive reinforcing properties of the drug. The present study was designed to assess whether voluntary ethanol intake would stimulate locomotor activity in Sardinian alcohol-preferring (sP) rats, selectively bred for high ethanol preference and consumption. Rats were habituated to a) consume either water alone (water-consuming rats) or ethanol (10%, v/v) as free choice together with water (ethanol-consuming rats) according to a 15-min limited access protocol for 10 consecutive days prior to the test, and b) explore an open field for 10 min immediately after the drinking session in a trial on 3 consecutive days before the test. On the test day, voluntary ethanol consumption in ethanol-consuming rats averaged 1.2 g/kg. Values for activity measures (time spent moving, number of square crossings and number of rearings) were significantly higher in ethanol- than in water-consuming rats at both 5- and 10-min intervals. These results suggest that the euphorigenic effects of ethanol, supposedly represented by the stimulation of locomotor activity, are part of the reinforcing properties of ethanol in sP rats.