Oral intake of sweetened or sweetened alcoholic beverages and open-field behavior

The relationship between the intake of sweetened alcoholic beverages and individual differences in an open field was assessed using an oral self-administration procedure in male Wistar rats (n = 41). After four sessions in the open field, rats were gradually reduced to 80% of their ad lib body weights over a 10-day period. Rats were then allowed to drink an alcohol-containing solution (10% v/v ethanol, 3% w/v glucose) (experimental group: n = 20) or a solution of glucose (3% w/v glucose) (control group: n = 21) for 1 h/day during 9 consecutive days. Experimental rats were divided into two groups on the basis of the mean daily ethanol dose ingested (g/kg/h) in the nine sessions. The high ethanol-consuming (HEI rats), when compared with the low ethanol-consuming rats (LEI rats), only showed a tendency (p = 0.062) towards fewer global number of rearings in the open field. No relationship between open-field defecation and ethanol intake was observed. With regard to the control rats, the higher consuming also showed lower number of rearings in the open held, similarly to the experimental rats. When we divided all experimental or control rats into two subgroups on the basis of the mean daily tap-water ingested during 23 h/day, no differences in the number of rearings were found. The results suggest that rearing in a novel environment could be a predictor of susceptibility to reinforcement by sweetened or palatable beverages.