Potentiation of LON 954 tremor by typical and atypical neuroleptics--an indication of striatal dopamine antagonism.

Tremor produced in laboratory mice by the benzylimidoylurea derivative LON 954 was potentiated in a dose-dependent manner by a variety of typical and atypical neuroleptics. The most effective agents in this respect were those shown by other workers to have a selective action at dopamine receptors, notably the butyrophenones, thioxanthines and fluphenazine. Chlorpromazine and prochlorperazine produced inconsistent effects while clozapine and loxapine respectively delayed and prolonged the peak tremor response. While these findings support primary involvement of striatal dopaminergic mechanisms in LON 954 tremorogenesis, a reduction in cyclic AMP levels may be an important factor in the observed effects.