A neuronal basis for the alerting action of (+)‐amphetamine

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Abstract
1 (+)-Amphetamine mimicked the excitatory and inhibitory actions of (—)-noradrenaline on single neurones in the brain stem of acute halothane-anaesthetized rats when these compounds were applied by iontophoresis. (+)-Amphetamine had no actions on neurones unaffected by (—)-noradrenaline. 2 These mimicking actions of (+)-amphetamine could not be observed 20 h after treatment of the animals with reserpine 5 mg/kg. 3 The enzyme inhibitors α-methyl-p-tyrosine and FLA 63 also greatly reduced the number of (—)-noradrenaline-mimicking responses to (+)-amphetamine. 4 In animals pretreated with α-methyl-p-tyrosine, but not in those pretreated with FLA 63, excitatory actions of (+)-amphetamine on neurones excited by (—)-noradrenaline could be elicited 45–90 min after systemic injection of l-DOPA. 5 These results indicate that (+)-amphetamine can release noradrenaline from presynaptic sites in the brain stem, which may be a basis for its alerting actions.