Influences of alcohol on the social responses of male resident mice to anosmic female intruders.

The effects of acutely administered ethanol (0, 0.5, 1.0 or 2.0 g/kg, i.p.) were studied in individually-housed male Swiss mice in dyadic encounters with anosmic, group-housed female intruders. The procedure was designed to suppress levels of attack in isolates. Videotape analysis of 500-second encounters, using both simplified and complex ethological techniques, revealed that alcohol did not potentiate aggression at any dose tested. At the highest alcohol dose there were marked increases in total time spent in timid-defensive and non-social behaviours, with concomitant decreases in aggressive and social/sexual activities. The postural analysis showed increases and decreases in elements of non-social behaviour and social investigatory elements, together with marked increases in certain timid-defensive activities and a decrease in tail-rattling. Comparison with previous work on inter-male paradigms shows that the type of opponent not only modifies the behaviour of saline-treated controls, but markedly influences the behavioural responses to alcohol treatment.