mu-Opioid receptor-knockout mice: the role of mu-opioid receptor in gastrointestinal transit

Brain Res Mol Brain Res. 1998 May;56(1-2):281-3. doi: 10.1016/s0169-328x(98)00051-5.


The role of mu-opioid receptor in gastrointestinal transit was investigated using mu-opioid receptor knockout mice (MOR-KO). Our result establishes unequivocally that inhibition of GI transit by morphine is a mu-opioid receptor mediated function. In addition, we show that neither delta nor kappa receptor agonist given supraspinally or peripherally are able to inhibit GI transit in MOR-KO animals. It was interesting to observe that basal GI motility was lower in MOR-KO (-/-) compared to heterozygous (+/-) and wild type (+/+) animals.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / administration & dosage
  • Animals
  • Enkephalin, D-Penicillamine (2,5)-
  • Enkephalins / administration & dosage
  • Gastrointestinal Transit / drug effects
  • Gastrointestinal Transit / genetics*
  • Injections, Intraventricular
  • Injections, Subcutaneous
  • Male
  • Mice
  • Mice, Knockout
  • Morphine / administration & dosage
  • Receptors, Opioid, mu / genetics*
  • Receptors, Opioid, mu / physiology*


  • Enkephalins
  • Receptors, Opioid, mu
  • 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
  • Morphine
  • Enkephalin, D-Penicillamine (2,5)-