Effects of ethanol on aggression in three inbred strains of mice

The effects of acutely administered ethanol (0, 0.5 and 1.0 g/kg, IP) were studied in 3 inbred strains of mice during 500 sec dyadic encounters with non-drugged, intruder "standard opponents." The test animals were male C57, DBA and BALB strain mice which had been isolated for 14 or 28 days to promote aggression. The times allocated to 6 broad categories of behaviour were measured from videotape recordings. There was no significant effect of ethanol on threat behaviour or overt aggression, except in 14 day isolates of the DBA strain where aggressive behaviour was reduced by the high dose. This dose increased flight/defensive and freezing behaviour in C57 and BALB mice isolated for 14 days. Ethanol did not affect non-social or social investigative behaviour, except in BALB mice where social behaviour was significantly reduced by the high dose. Blood ethanol levels were similar in DBA and C57 strain mice but were significantly lower in BALB mice.