Blockade of dopamine D1 receptors by SCH 23390 antagonizes discriminative stimulus effects of pentazocine.
The purpose of this investigation was to test the hypothesis that the discriminative stimulus properties of pentazocine are mediated through an interaction with dopamine receptors. Rats were trained to discriminate s.c. injections of pentazocine (3.0 mg/kg) from vehicle in a two-choice discrete trial avoidance paradigm. SCH 23390 (0.003-0.056 mg/kg), a selective antagonist of dopamine D1 receptors, inhibited the discriminative stimulus effects of pentazocine in a dose-dependent fashion, whilst the selective D2 receptor antagonist sulpiride (20.0-80.0 mg/kg) did not antagonize them. It appears that the dopamine D1 receptors play an important role in the discriminative stimulus effects of pentazocine.
Ukai
M
M
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
Nakayama
S
S
Hamada
T
T
Kameyama
T
T
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects*; D018492:Dopamine Antagonists; D004305:Dose-Response Relationship, Drug; D008297:Male; D010423:Pentazocine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*; D017447:Receptors, Dopamine D1; D013469:Sulpiride / Q000494:pharmacology
D001552:Benzazepines; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D013469:Sulpiride; D010423:Pentazocine