Levels, metabolism, and pharmacological activity of anandamide in CB(1) cannabinoid receptor knockout mice: evidence for non-CB(1), non-CB(2) receptor-mediated actions of anandamide in mouse brain

J Neurochem. 2000 Dec;75(6):2434-44. doi: 10.1046/j.1471-4159.2000.0752434.x.


Anandamide [arachidonylethanolamide (AEA)] appears to be an endogenous agonist of brain cannabinoid receptors (CB(1)), yet some of the neurobehavioral effects of this compound in mice are unaffected by a selective CB(1) antagonist. We studied the levels, pharmacological actions, and degradation of AEA in transgenic mice lacking the CB(1) gene. We quantified AEA and the other endocannabinoid, 2-arachidonoyl glycerol, in six brain regions and the spinal cord by isotope-dilution liquid chromatography-mass spectrometry. The distribution of endocannabinoids and their inactivating enzyme, fatty acid amide hydrolase, were found to overlap with CB(1) distribution only in part. In CB(1) knockout homozygotes (CB(1)-/-), the hippocampus and, to a lesser extent, the striatum exhibited lower AEA levels as compared with wild-type (CB(1)+/+) controls. These data suggest a ligand/receptor relationship between AEA and CB(1) in these two brain regions, where tonic activation of the receptor may tightly regulate the biosynthesis of its endogenous ligand. 2-Arachidonoyl glycerol levels and fatty acid amide hydrolase activity were unchanged in CB(1)-/- with respect to CB(1)+/+ mice in all regions. AEA and Delta(9)-tetrahydrocannabinol (THC) were tested in CB(1)-/- mice for their capability of inducing analgesia and catalepsy and decreasing spontaneous activity. The effects of AEA, unlike THC, were not decreased in CB(1)-/- mice. AEA, but not THC, stimulated GTPgammaS binding in brain membranes from CB(1)-/- mice, and this stimulation was insensitive to CB(1) and CB(2) antagonists. We suggest that non-CB(1), non-CB(2) G protein-coupled receptors might mediate in mice some of the neuro-behavioral actions of AEA.

Publication types

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

MeSH terms

  • Amidohydrolases / metabolism
  • Animals
  • Arachidonic Acids / analysis
  • Arachidonic Acids / metabolism*
  • Arachidonic Acids / pharmacology*
  • Brain / drug effects
  • Brain / metabolism*
  • Brain Chemistry / drug effects
  • Brain Chemistry / genetics
  • Cannabinoid Receptor Modulators
  • Cell Membrane / metabolism
  • Dose-Response Relationship, Drug
  • Dronabinol / pharmacology
  • Endocannabinoids
  • Female
  • Glycerides / metabolism
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Organ Specificity
  • Polyunsaturated Alkamides
  • Receptors, Cannabinoid
  • Receptors, Drug / deficiency
  • Receptors, Drug / genetics*


  • Arachidonic Acids
  • Cannabinoid Receptor Modulators
  • Endocannabinoids
  • Glycerides
  • Polyunsaturated Alkamides
  • Receptors, Cannabinoid
  • Receptors, Drug
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Dronabinol
  • glyceryl 2-arachidonate
  • Amidohydrolases
  • fatty-acid amide hydrolase
  • anandamide