Comparison of discriminative and reinforcing stimulus characteristics of morphine-like opioids and two met-enkephalin analogues

James H. Woods, Seymore Herling, Alice M. Young

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The reinforcing and discriminative stimulus properties of two met-enkephalin analogues (FK 33-824 and FW 34-569) were compared to those of morphine and other morphine-like opioids in rhesus monkeys. Intravenous injection of the two met-enkephalin analogues maintained response rates lower that those maintained by either morphine or codeine. This differences was not due to a lack of similarity between the interoceptive stimulus effects of the enkephalins and those of morphine-like opioids, since the enkephalin analogues were found to share discriminative stimulus effects with morphine, codeine, and etorphine. FK 33-824 and FW 34-569, however, had a slower onset of discriminative effect than either morphine or codeine. This slow onset of effect may account for the limited reinforcing effect of these enkephalin analogues.

Original languageEnglish (US)
Pages (from-to)409-419
Number of pages11
JournalNeuropeptides
Volume1
Issue number6
DOIs
StatePublished - Aug 1981
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology
  • Neurology
  • Endocrine and Autonomic Systems
  • Cellular and Molecular Neuroscience

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