G protein-coupled receptor 18
GPR18 Gene
RNA expression pattern

N-arachidonyl glycine receptor also known as G-protein coupled receptor 18 (GPR18) is a protein that in humans is encoded by the GPR18 gene.[1][2] Along with the other previously "orphan" receptors GPR55 and GPR119, GPR18 has been found to be a receptor for endogenous lipid neurotransmitters, several of which also bind to cannabinoid receptors.[3][4][5]

Recent research supports the hypothesis that GPR18 is the abnormal cannabidiol receptor and N-arachidonoyl glycine, the endogenous lipid metabolite of anandamide, initiates directed microglial migration in the CNS through activation of GPR18.[6]



Ligands found to bind to GPR18 as agonists include:[6][7]

  • N-arachidonoyl glycine (NAGly)
  • Abnormal cannabidiol (Abn-CBD)
  • AM-251 - partial agonist
  • Cannabidiol - partial agonist
  • O-1602
  • Δ9-Tetrahydrocannabinol9-THC) - THC is actually a more potent agonist at GPR18 than at CB1 or CB2, with Ki of 0.96nM at GPR18, 8.1nM at GPR55, 25.1nM at CB1 and 35.2nM at CB2.[8]
  • Anandamide (N-arachidonoyl ethanolamine, AEA)
  • Arachidonylcyclopropylamide (ACPA) [9]
  • O-1918


Further reading