Improvement of shuttle-box performance of mice by combinations of benzodiazepines and morphine given during training.

Chlorodiazepoxide, diazepam and morphine, given alone or in combination, were tested in naive mice subjected to five 100-trial avoidance sessions in the shuttle-box. When given alone before each training session all three drugs improved avoidance behaviour. However, facilitation of avoidance responding was much more evident when either benzodiazepine derivative was given in combination with morphine.