INTERACTIONS OF (+)-AMPHETAMINE AND CHLORPROMAZINE ON NEURONS IN THE LOWER BRAIN-STEM OF THE RAT

The ability of chlorpromazine to antagonize the effects of iontophoretic application of (+)‐amphetamine to single neurones in the medulla and lower pons of anaesthetized rats has been studied. Chlorpromazine, administered systemically or iontophoretically, consistently and specifically antagonized the excitatory actions of (+)‐amphetamine, but not those of noradrenaline on the same neurone. It is concluded that chlorpromazine reduces the effect of (+)‐amphetamine by a presynaptic mechanism. (+)‐Amphetamine did not mimic the prolonged inhibitory response of some neurones to noradrenaline but often excited these neurones and chlorpromazine blocked these excitatory responses to (+)‐amphetamine. 1979 British Pharmacological Society