The effect of age on the behavioral responses of mice following diazepam and midazolam sedation in combination with nitrous oxide.

This study examined the effects of age on the behavior of mice administered one of two benzodiazepines with and without nitrous oxide. Young (3 wk +/- 3 days) and adolescent (7 wk +/- 3 days) male DBA-2 mice were administered oral diazepam (2.0 or 3.5 mg/kg), midazolam (0.75 or 1.2 mg/kg), or a placebo in combination with 50% nitrous oxide/50% oxygen, or room air. The mouse staircase model was used, where the number of rears (NR) served as an index of anxiety, and the number of steps ascended (NSA) as an index of sedation. No significant differences in the responses between the ages were noted. Nitrous oxide seemed to increase the NR and NSA, whereas the benzodiazepines alone did not affect behavior. These DBA-2 mice may represent a strain that is less sensitive to the anxiolytic-sedative effects of the benzodiazepines than are other strains.