Behavioral screening of two mouse lines selected for different brain weight

1. Several behavioral tests were used to compare two lines of mice selected for large (LB) and small brain (SB) weight on the basis of brain/body weig ht ratio values. 2. An elevated pain sensitivity as well as more intense startle response wa s shown in SE mice in comparison with LB mice. 3. In inescapable situations of slip funnel and tail suspension tests, anal ogues of the Porsolt swim test, higher immobility scores in SE mice suggest an increased level of fear and/or anxiety in the stress situations. 4. The SE mice demonstrated higher levels of locomotion in open field and c ross-maze tests. In the latter test, the SE mice also showed an increased t endency for stereotyped alternation of two arms during maze exploration. 5. Acute administration of a moderate dose of ethanol (3 g/kg) had opposite effects on the total time of cross-maze exploration: this measure increase d in the SE and decreased in the LB line. By contrast, the tendency for ste reotypy was similarly increased and the efficacy of maze exploration decrea sed in both lines.