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Psychotomimesis mediated by kappa opiate receptors.

A Pfeiffer, V Brantl, A Herz, H M Emrich

Science August 15, 1986 DOI: 10.1126/science.3016896 (opens in new tab)

Study at a glance

AI-extracted from the abstract
Characteristics Experimental pharmacological study Peer reviewed
Population Male subjects
Intervention naloxone
Key findings The opiate-active (-)-isomer of the kappa agonist MR 2033 produced dose-dependent dysphoric and psychotomimetic effects in male subjects that were antagonized by naloxone, while the (+)-isomer did not. The authors conclude that kappa opiate receptors appear to mediate psychotomimetic effects and propose that kappa and mu opioid systems exert opposing influences on emotional and perceptual experiences.

Abstract

The kappa opioid agonists are analgesics that seem to be free of undesired morphine-like effects. Their dysphoric actions observed with the kappa agonist cyclazocine are thought to be mediated by an action at sigma-phencyclidine receptors. The benzomorphan kappa agonist MR 2033 is inactive at sigma-phencyclidine receptors. In male subjects, the opiate-active (-)-isomer, but not the (+)-isomer, elicited dose-dependent dysphoric and psychotomimetic effects that were antagonized by naloxone. Thus, kappa opiate receptors seem to mediate psychotomimetic effects. In view of the euphorigenic properties of mu agonists, our results imply the existence of opposed opioid systems affecting emotional and perceptual experiences.

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