A neuronal basis for the alerting action of (+)-amphetamine.
1. (+)-Amphetamine mimicked the excitatory and inhibitory actions of (-)-noradrenaline on single neurones in the brain stem of acute halothaneanaesthetized 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 alpha-methyl-p-tyrosine and FLA 63 also greatly reduced the number of (-)-noradrenaline-mimicking responses to (+)-amphetamine.4. In animals pretreated with alpha-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.
D000200:Action Potentials; D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D002395:Catecholamines / Q000502:physiology; D003913:Dextroamphetamine / Q000494:pharmacology*; D004295:Dihydroxyphenylalanine / Q000494:pharmacology; D007274:Injections, Intraperitoneal; D007478:Iontophoresis; D008781:Methyltyrosines / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D009638:Norepinephrine / Q000502:physiology; D051381:Rats; D012110:Reserpine; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors
D002395:Catecholamines; D008781:Methyltyrosines; D013859:Thiocarbamates; D004295:Dihydroxyphenylalanine; D012110:Reserpine; D003913:Dextroamphetamine; D009638:Norepinephrine