Production of catalepsy and depletion of brain monoamines by a butyrophenone derivative.

1 The cataleptic and monoamine-depleting effects of a butyrophenone derivative (4'-fluoro-4-[[4-(p-fluorophenyl)-3-cyclohexen-1-yl]-amino]-butyrophenone hydrochloride, U-32, 802A) were studied in rats and mice and compared with those of tetrabenazine. 2 Catalepsy was evaluated by means of a modified grid test which allowed the repetition of the test in the same animal several times without affecting the results. Both drugs produced a dose-related cataleptic state of similar time course. 3 Like tetrabenazine, U-32, 802A induced a large reduction in the content of 5-hydroxytryptamine, dopamine and noradrenaline in different parts of the brain, with a concomitant elevation in the metabolites 5-hydroxyindol-3-yl acetic acid and homovanillic acid. The time courses of the catalepsy and the reduction in brain monoamines were very similar. 4 The activity of U-32, 802A suggested that the drug, although chemically a butyrophenone, might act primarily at the presynaptic organelle for storage of monoamines in a way similar to tetrabenazine.