A presynaptic site of action within the mesencephalic reticular formation for (+)-amphetamine-induced electrocortical desynchronization.
1. Changes induced in the electrocorticogram by the bilateral perfusion of (+)-amphetamine into the mesencephalic reticular formation (MRF) have been studied in cat encéphale isolé preparations. 2. (+)-Amphetamine, applied for 5 min in the MRF, mimicked the electrocortical desynchronization induced by the perfusion of (-)-noradrenaline (NA) or (-)-alpha-methylnoradrenaline (AMNA) into the same sites. 3. Perfusion of 6-hydroxydopamine (6-OHDA) also induced desynchronization but, over the 1 h perfusion period, slow wave activity gradually returned to the electrical record. 4. Following the application of 6-OHDA the effect of (+)-amphetamine was abolished or significantly attenuated, whereas the effect of NA or AMNA was not affected. 5. The electrocortical desynchronization induced by (+)-amphetamine could be restored if its application was preceded by perfusion with NA or AMNA. 6. Fluorescence studies using AMNA indicated that 6-OHDA depleted noradrenergic nerve terminals near the cannulae tips. However, the terminals were still capable of taking up exogenously applied AMNA. 7. These results suggest that (+)-amphetamine has a presynaptic action on noradrenergic nerve terminals within the MRF.
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002415:Cats; D003344:Cortical Synchronization; D003655:Decerebrate State / Q000503:physiopathology; D003913:Dextroamphetamine / Q000494:pharmacology*; D004569:Electroencephalography; D006892:Hydroxydopamines / Q000494:pharmacology; D008636:Mesencephalon / Q000187:drug effects* / Q000648:ultrastructure; D009638:Norepinephrine / Q000494:pharmacology; D012154:Reticular Formation / Q000187:drug effects* / Q000648:ultrastructure; D013569:Synapses / Q000187:drug effects*
D006892:Hydroxydopamines; D003913:Dextroamphetamine; D009638:Norepinephrine