Evidence that the cannabinoid CB1 receptor is a 2-arachidonoylglycerol receptor. Structure-activity relationship of 2-arachidonoylglycerol, ether-linked analogues, and related compounds

J Biol Chem. 1999 Jan 29;274(5):2794-801. doi: 10.1074/jbc.274.5.2794.

Abstract

An endogenous cannabimimetic molecule, 2-arachidonoylglycerol, induces a rapid, transient increase in intracellular free Ca2+ concentrations in NG108-15 cells through a cannabinoid CB1 receptor-dependent mechanism. We examined the activities of 24 relevant compounds (2-arachidonoylglycerol, its structural analogues, and several synthetic cannabinoids). We found that 2-arachidonoylglycerol is the most potent compound examined so far: its activity was detectable from as low as 0.3 nM, and the maximal response induced by 2-arachidonoylglycerol exceeded the responses induced by others. Activities of HU-210 and CP55940, potent cannabinoid receptor agonists, were also detectable from as low as 0.3 nM, whereas the maximal responses induced by these compounds were low compared with 2-arachidonoylglycerol. Anandamide was also found to act as a partial agonist in this assay system. We confirmed that free arachidonic acid failed to elicit a response. Furthermore, we found that a metabolically stable ether-linked analogue of 2-arachidonoylglycerol possesses appreciable agonistic activity, although its activity was apparently lower than that of 2-arachidonoylglycerol. We also confirmed that pretreating cells with various cannabinoid receptor agonists nullified the response induced by 2-arachidonoylglycerol, whereas pretreating cells with other neurotransmitters or neuromodulators did not affect the response. These results strongly suggested that the cannabinoid CB1 receptor is originally a 2-arachidonoylglycerol receptor, and 2-arachidonoylglycerol is the intrinsic physiological ligand for the cannabinoid CB1 receptor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonic Acids / chemistry*
  • Arachidonic Acids / metabolism
  • Benzoxazines
  • Cannabinoids / antagonists & inhibitors
  • Cannabinoids / metabolism*
  • Cell Line
  • Cyclohexanols / pharmacology
  • Dronabinol / analogs & derivatives
  • Dronabinol / pharmacology
  • Endocannabinoids
  • Models, Chemical
  • Morpholines / pharmacology
  • Naphthalenes / pharmacology
  • Piperidines / pharmacology
  • Polyunsaturated Alkamides
  • Pyrazoles / pharmacology
  • Rats
  • Receptors, Cannabinoid
  • Receptors, Drug / agonists
  • Receptors, Drug / metabolism*
  • Rimonabant
  • Structure-Activity Relationship

Substances

  • Arachidonic Acids
  • Benzoxazines
  • Cannabinoids
  • Cyclohexanols
  • Endocannabinoids
  • Morpholines
  • Naphthalenes
  • Piperidines
  • Polyunsaturated Alkamides
  • Pyrazoles
  • Receptors, Cannabinoid
  • Receptors, Drug
  • Win 55212-2
  • Dronabinol
  • 3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol
  • HU 211
  • Rimonabant
  • anandamide