Dopaminergic system is widely implicated in learning and memory in rodents. Several studies have shown that antipsychotics (typical and atypical) interact strongly with dopamine receptors. Typical antipsychotics are known to impair memory in rodents while the effects of the atypical on memory retention need more exploration. In this work, we used a one-trial passive avoidance task with mice (C57BL/6J) to evaluate the effect of clozapine (0.3, 1, 3 mg/kg), some new atypical compounds like quetiapine (0.3, 1, 3, 10, 30 mg/kg), olanzapine (0.3, 1, 3 mg/kg), risperidone (0.3, 1, 3 mg/kg) and finally JL13, 5-(4-piperazin-1-yl)-8-chloro-pyrido[2,3-b][1,5]benzoxazepine fumarate, (1, 3, 10 mg/kg), a putative new antipsychotic on the retention. The training session consists in the administration of a foot-shock (0.3 mA) immediately after entry in the dark compartment (step-through). The tested drugs or saline were administred intraperitoneally after about 30 seconds of the shock. The assess of retention time was realized by measuring the step-trough latency 24 h later. The increase of this latency show an improvement of the retention while its decrease shows an impairement. Our results show an increase in the retention time for risperidone (1 mg/kg), JL13 (1 and 3 mg/kg) and quetiapine (1 and 3 mg/kg). Olanzapine shows no significant effect in retention time. Because the atypical antipsychotics tested in this work show a multiple-receptors binding profile, the mechanisms underlying their effect on retention time remain to be determined.

Acknowlegment C.L. was financially supported by a grant from the "Patrimoine de l'Université de Liège". J.-F.L. is Senior Research Associate of the "Fonds National pour la Recherche Scientifique (F.N.R.S.)" of Belgium. A.G. is Research Fellow of the « Fonds pour la formation à la Recherche Industrielle et Agricole (F.R.I.A.) >>.