Abstract
Buzzers and shocks were presented in random sequence and with no temporal association to rats in a shuttle-box, so that they performed pseudoconditioned barrier-crossing responses to the buzzer. Performance of these responses was enhanced by amphetamine and tyramine. The adrenergic blocking agents yohimbine and dibenamine, though ineffective on their own, antagonized the action of amphetamine and tyramine. Hexamethonium and methylatropine, also ineffective by themselves, potentiated the effect of amphetamine but not that of tyramine. Eserine depressed the performance of pseudoconditioned responses when given alone, and it antagonized the stimulant action of both amphetamine and tyramine. The results suggest that amphetamine and tyramine enhance pseudoconditioning through activation of a peripheral adrenergic mechanism and that amphetamine, in addition, triggers an opposing cholinergic mechanism, also peripheral, from which it can be released by the anticholinergic agents hexamethonium and methylatropine. The depressant action of eserine can also be explained by activation of the cholinergic mechanism.
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Izquierdo, I. Possible peripheral adrenergic and cholinergic mechanisms in pseudoconditioning. Psychopharmacologia 35, 189–193 (1974). https://doi.org/10.1007/BF00437747
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DOI: https://doi.org/10.1007/BF00437747