Abstract
The present experiments assessed whether morphine-conditioned hyperactivity could be attenuated by either the opiate antagonist naloxone or the dopamine antagonist pimozide. Both of these antagonists were shown to block the unconditioned hyperactivity induced by 2 mg/kg morphine (Experiment 1). Rats were then conditioned by pairing this dose of morphine repeatedly with a distinctive environment (Experiment 2). Following several drug-environment pairings, rats displayed a hyperactive conditioned response (CR) when exposed to the environment in the absence of the drug. CR expression was counteracted by 1 mg/kg naloxone and was attenuated by pimozide (0.25, 0.33, and 0.4 mg/kg) in a dose-related manner. These findings suggest that the unconditioned and conditioned hyperactive responses produced by morphine may involve similar neuropharmacologic substrates.
Original language | English |
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Pages (from-to) | 314-319 |
Number of pages | 6 |
Journal | Psychopharmacology |
Volume | 93 |
Issue number | 3 |
DOIs | |
State | Published - Nov 1987 |
Keywords
- Classical conditioning
- Conditioned hyperactivity
- Morphine
- Naloxone
- Pimozide
ASJC Scopus subject areas
- Pharmacology