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Effects of opioid ligands on the relative reinforcing strength of food and saline in monkeys trained under concurrent FR30 schedules of food and heroin availability
Author(s) -
Paronis Carol A,
Bergman Jack
Publication year - 2008
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.22.1_supplement.712.6
Subject(s) - heroin , nalbuphine , saline , pharmacology , morphine , opioid , self administration , buprenorphine , butorphanol , medicine , anesthesia , drug , receptor
Previous studies in monkeys trained to “choose” between injections of heroin or delivery of food pellets revealed that buprenorphine increased the relative reinforcing strength of low, but not high, doses of heroin while antagonizing some of the direct effects of heroin. The present studies extend these findings by evaluating the effects of mu‐opioid full and partial agonists in rhesus monkeys responding under concurrent FR30 schedules (30 responses on one lever results in food delivery, 30 responses on the alternative lever results in i.v. injection of saline or heroin). Under this schedule, the distribution of behavior is related to available i.v. dose: when saline, 0.003 and 0.01 mg/kg/inj heroin are available 4, 37, and 88% of responses, respectively, occur on the injection lever. Opioid ligands were studied by administering doses 10 min before the start of the session. Preliminary results indicate that, like morphine, codeine (0.3–3.0 mg/kg) butorphanol (0.003–0.03 mg/kg) and nalbuphine (0.03–0.3 mg/kg) all dose‐dependently increase responding on the injection lever during sessions of saline availability. These results suggest that the effects of opioid ligands on the relative reinforcing strength of saline or food do not depend on the efficacy of the pretreatment drug. Ongoing studies are evaluating the effects of these drugs on the relative reinforcing strength of heroin. (Supported by NIH Grant DA15723)