Possible mechanism of haloperidol-induced enhancement of memory retrieval.

The effects of pretest administration of haloperidol on retention of a step-through passive avoidance task was studied with a 3-day training and retention test interval. Haloperidol at doses of 0.3 mg/kg and 0.5 mg/kg i.p. enhanced memory retrieval. This effect of haloperidol is possibly mediated by interaction with alpha 2-adrenergic receptors, that results in increasing the noradrenergic transmission, or it could be due to direct interaction with dopamine receptors. Yohimbine (2.5 mg/kg) also enhanced memory retrieval, as shown by haloperidol. Clonidine (0.05 mg/kg) significantly antagonized the effect of haloperidol on memory retrieval. Scopolamine (0.5 mg/kg) did not have any effect on enhancement of memory produced by haloperidol.