 Comparisons between normal and neurotensin-deficient mice revealed striking differences in the ability of different antipsychotic drugs to augment PPI.While the atypical antipsychotic drug clozapine augmented PPI normally in neurotensin-deficient mice, the conventional antipsychotic haloperidol and the newer atypical antipsychotic quetiapine were ineffective in these mice, in contrast to normal mice where these drugs significantly augmented PPI.These results suggest that certain antipsychotic drugs require neurotensin for at least some of their effects.