WAY100635 and latent inhibition in the rat: selective effects at preexposure

The influence of the selective, silent 5HT1a antagonist WAY100635 (Wyeth Research Ltd) on the latent inhibition effect was examined in a within-subject, on-baseline conditioned suppression procedure in rats. WAY100635 was found to enhance the latent inhibition effect, producing a retardation in the acquisition of conditioned suppression following a level of stimulus preexposure known to be insufficient to produce a latent inhibition effect in control animals. This influence of the drug was restricted to its actions during the preexposure phase of the experiment, and the drug also abolished the unconditioned suppression of lever pressing that occurs on the first presentation of a novel auditory stimulus. These findings are discussed in terms of the possible influence of serotonergic manipulations on contextual processing, and also have important implications for current animal models of schizophrenia which stress the role of dopaminergic mechanisms in latent inhibition.