An ethological analysis of the effects of diazepam and nitrazepam on the responses of female mice to anosmic males encountered in a novel arena.

The effects of acutely administered benzodiazepines have largely been validated in male animals, in spite of the fact that the majority of anti-anxiety drugs are prescribed for female patients. A study was carried out assessing the potential of female mice in the testing of the anxiolytic properties of drugs. Three doses (0.5, 1.0 and 2.0mg/kg) of the benzodiazepines diazepam and nitrazepam were given to individually-housed female Swiss mice before dyadic encounters with anosmic, group-housed males. Videotape analysis of the encounters, using an ethopharmacological technique, revealed suppressive effects of diazepam (1.0 and 2.0mg/kg) and nitrazepam (all doses) on avoidance/flee, confirming the anxiolytic properties of these drugs. However, some doses of diazepam (2.0mg/kg) and nitrazepam (1.0mg/kg), greatly increased immobility with little effect on active behavioural elements. It is suggested that "immobility" does not simply measure sedation.