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Discrimination among saline, mu and kappa agonists, and combinations of mu and kappa agonists in pigeons trained under a four‐choice procedure
Author(s) -
McMillan Donald Edgar,
Li Mi,
Wessinger William D.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a681
Subject(s) - morphine , saline , kappa , pharmacology , κ opioid receptor , chemistry , agonist , receptor , anesthesia , medicine , mathematics , biochemistry , geometry
Pigeons were trained to discriminate among saline, 5 mg/kg morphine, 5 mg/kg U50,448, and a combination of these drug doses. Trained pigeons responded on the appropriate key 94% of the time. When dose‐response curves were determined pigeons responded on the appropriate key at doses of 3–5.6 mg/kg and above of either morphine or U50,448. Combinations of 1 mg/kg morphine and 1 mg/kg U50,448 produced responding on the saline key, but higher doses of U50,488 combined with 1 mg/kg morphine produced responding on the U50,448 key. Combinations of 3–10 mg/kg morphine with 1 mg/kg U50,448 produced responding on the morphine key, while combination of higher doses of U50,448 with these doses of morphine produced progressively more responding on the drug‐combination key. The use of this four‐choice procedure provides a unique opportunity to study the effects of mixed agonists that produce their effects by acting at both mu and kappa receptors. Supported by NIDA Grant DA 02251‐25.