Abstract
In a Pavlovian conditioning procedure, rats were exposed to an odor conditioned stimulus (CS) and then were given morphine with its effect serving as the unconditioned stimulus (US). After four OS-US pairings, the CS was tested alone to assess the presence of an analgesic conditioned response (CR) using a hot-plate test. In Experiment 1a, two groups were conditioned by pairing either 10 mg/kg morphine or saline with an odor CS. In Experiment 1b, two groups were given an odor CS paired or unpaired with 10 mg/kg morphine. These results established that an odor cue can support a morphine-induced analgesic CR. Experiment 2 characterized tile dose-effect curve (0, 3, 10, and 30 mg/kg morphine) using an odor conditioning procedure. The dose-effect curve showed all inverted U-shaped function, with the 10 mg/kg morphine group having significantly longer paw-lick latencies compared to all other groups. This finding contrasts with the monotonically ascending dose-effect curve for the analgesic unconditioned response (UR) to morphine.
Original language | English |
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Pages (from-to) | 115-118 |
Number of pages | 4 |
Journal | Pharmacology Biochemistry and Behavior |
Volume | 60 |
Issue number | 1 |
DOIs | |
State | Published - May 1998 |
Bibliographical note
Funding Information:This research was supported by USPHS Grant DA07746. We thank Melinda Marion for expert technical assistance.
Keywords
- Analgesia
- Conditioning
- Hot plate
- Morphine
- Odor
- Paw lick
ASJC Scopus subject areas
- Biochemistry
- Toxicology
- Pharmacology
- Clinical Biochemistry
- Biological Psychiatry
- Behavioral Neuroscience