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Effects of opioids in rats trained to discriminate 22 from 2 hours food deprivation
Author(s) -
Jewett David C.,
Hahn Thomas W.,
Fiksdal Britta L.,
Tham Rachel L.,
Wiebelhaus Jason M.,
Kwilasz Andrew J.,
Smith Travis R.,
Grace Martha K.,
Levine Allen S.
Publication year - 2007
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.21.5.a411-d
Subject(s) - naltrexone , opioid antagonist , endocrinology , medicine , stimulus control , opioid , opioid receptor , damgo , stimulus (psychology) , maternal deprivation , psychology , receptor , (+) naloxone , nicotine , psychotherapist
Opioid agonists produce modest increases in food intake in several species. We examined the effects of centrally‐administered, opioid agonists in rats trained to discriminate between 22 and 2 hours food deprivation in an operant choice task. Previously we showed that neuropeptide Y and ghrelin induced discriminative stimulus effects similar to 2‐ hours food deprivation. In the present study we asked if opioid agonists would induce similar effects. After acquisition of the deprivation discrimination, rats were food restricted for 2 hours and injected with doses of DAMGO, DSLET, or orphanin previously shown to reliably increase food intake. All injections were made into the paraventricular nucleus of the hypothalamus (PVN). DAMGO, DSLET, and orphanin did not produce 22‐hour deprivation‐like discriminative stimulus effects. We also examined the ability of the opioid antagonist naltrexone to modify the discriminative stimulus effects of 22 hours deprivation. Although the opioid antagonist naltrexone reduces deprivation and NPY‐induced feeding, naltrexone (0.3–10 mg/kg, s.c. or 1 to 10 μg, PVN) did not affect the discriminative stimulus effects of 22‐hours food deprivation or the effects of NPY. To date, we have found opioids tend to produce different effects than NPY or ghrelin in rats trained to discriminate between 2‐ and 22‐hours food deprivation. Our findings suggest drug discrimination techniques may be useful in assessing factors regulating feeding. Supported by UW‐Eau Claire Faculty/Student Research Collaboration. NIH, and the Department of Veterans Affairs.