The object recognition task in rats and mice: A simple and rapid model in safety pharmacology to detect amnesic properties of a new chemical entity

IntroductionThe aim of the present study was to evaluate the potential usefulness of the object recognition learning paradigm to detect the potential amnesic properties of a new drug for use in the characterisation of its safety pharmacology profile.Methods and ResultsIn the first experiment, the time-dependent decay of object recognition memory was characterised in Sprague–Dawley rats and C57Bl/6J mice. Under our experimental conditions, it takes between 3 and 4 post-training hours for the rats and between 1 and 2 post-training hours for the mice to forget the respective value of the objects. In the second experiment, the effects of scopolamine (0.03–1 mg/kg) were investigated in both rats and mice when administered 30 min prior to training in the object recognition task. Memory retention was tested 2 h after training in rats and 1 h after training in mice. Scopolamine impairs the object recognition memory at doses of 0.1, 0.3, and 1 mg/kg in rats and at doses of 0.3 and 1 mg/kg in mice. In the last experiment, effects of two benzodiazepines (alprazolam and diazepam) were assessed in the mouse model of object recognition task. Diazepam and alprazolam were intraperitoneally administered 30 min prior to training and memory retention was tested 10 min and 1 h after training. At 0.2 mg/kg, both benzodiazepines impair object recognition memory when testing is performed 1 h after training. However, when testing is performed 10 min after training, both benzodiazepines at 0.2 mg/kg failed to disrupt memory processes.DiscussionTaken together, these results show that the object recognition task can easily be performed in rats and mice for safety pharmacology studies related to CNS function. Because of the ageing population and the increasing number of drugs prescribed to elderly patients, it becomes important to evaluate the potential side effects of a new chemical entity on memory function during evaluation of its safety profile. The object recognition task, which is simple, rapid, and reliable, should be of great use in safety pharmacology to detect amnesic properties of new compounds.