Congenic C57BL/6 μ opiate receptor (MOR) knockout mice: Baseline and opiate effects

F. S. Hall, X. F. Li, M. Goeb, S. Roff, H. Hoggatt, I. Sora, G. R. Uhl

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Homozygous μ-opioid receptor (MOR) knockout (KO) mice developed on a chimeric C57B6/129SV background lack morphine-induced antinociception, locomotion and reward. Therefore it appears that MOR largely mediates these morphine actions. However, one factor that could affect the extent of knockout deficits in morphine-induced behavior is the genetic background against which the gene deletion is expressed. To examine the effect of genetic background chimeric C57B6/129SV MOR knockout mice from the 15th generation of those developed in our laboratory were backcrossed for 10 successive generations with C57BL/6 mice, a strain which is more sensitive to many of the properties of morphine, to produce congenic MOR (conMOR) KO mice. Heterozygote conMOR KO mice display attenuated morphine locomotion and reduced morphine analgesia compared to wild-type mice. Homozygote conMOR KO mice display baseline hyperalgesia, no morphine place preference, no morphine analgesia and no morphine locomotion. These results are not qualitatively different from those observed in the MOR KO strain with a chimeric C57B6/129SV background, and suggest that although the strain has separate influences on these functions, it does not substantially interact with deletion of the μ opiate receptor gene.

Original languageEnglish (US)
Pages (from-to)114-121
Number of pages8
JournalGenes, Brain and Behavior
Issue number2
StatePublished - Apr 2003
Externally publishedYes


  • Analgesia
  • Conditioned place preference
  • Congenic
  • Locomotion
  • Transgenic knockout mice

ASJC Scopus subject areas

  • Neuroscience(all)
  • Genetics


Dive into the research topics of 'Congenic C57BL/6 μ opiate receptor (MOR) knockout mice: Baseline and opiate effects'. Together they form a unique fingerprint.

Cite this