Cannabinoid receptor-mediated inhibition of acetylcholine release from hippocampal and cortical synaptosomes

Br J Pharmacol. 2000 Oct;131(3):645-50. doi: 10.1038/sj.bjp.0703599.


In previous studies cannabinoid agonists have been found to inhibit and cannabinoid antagonists to enhance electrically-evoked [(3)H]-acetycholine (ACh) release in hippocampal slices. The present study was undertaken to determine if similar cannabinoid effects could be observed in synaptosomes. [(3)H]-ACh release was evoked by two methods, both sensitive to presynaptic receptor effects. The first involved the addition of 1.3 mM calcium following perfusion with calcium-free Krebs and the second the addition of 11 mM potassium following perfusion with normal Krebs. In hippocampal synaptosomes the 1.3 mM calcium-evoked release and the high potassium-evoked [(3)H]-ACh release were inhibited by the cannabinoid agonist, WIN 55212-2, by 59 and 39%, respectively, and with an EC(50) of approximately 1 nM. WIN 55212-2 produced a similar, although less potent, inhibition of [(3)H]-ACh release in cortical synaptosomes. No inhibitory effect of WIN 55212-2 on [(3)H]-ACh release in striatal synaptosomes was observed, supporting previous data collected in this area with brain slices. The cannabinoid antagonist, SR 141716A, produced a robust enhancement of 1.3 mM calcium-evoked [(3)H]-ACh release in hippocampal synaptosomes (EC(50)<0.3 nM) but had no effect on potassium-evoked release or on [(3)H]-ACh release in the cortex or striatum. In conclusion our data demonstrates the inhibitory effects of WIN 55212-2 observed on ACh release in brain slices can be observed in hippocampal and cortex synaptosomes, suggesting a direct action of these compounds on the synaptic terminals. The SR 141716A-induced enhancement of ACh release can similarly be observed in hippocampal synaptosomes and is probably due to an inverse agonist action at constitutively active receptors.

Publication types

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

MeSH terms

  • Acetylcholine / metabolism*
  • Animals
  • Benzoxazines
  • Calcium Channel Blockers / pharmacology
  • Cannabinoids / metabolism
  • Cerebral Cortex / metabolism*
  • Hippocampus / metabolism*
  • In Vitro Techniques
  • Male
  • Morpholines / pharmacology
  • Naphthalenes / pharmacology
  • Piperidines / pharmacology
  • Pyrazoles / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Cannabinoid
  • Receptors, Drug / agonists
  • Receptors, Drug / antagonists & inhibitors
  • Receptors, Drug / physiology*
  • Rimonabant
  • Synaptosomes / metabolism*


  • Benzoxazines
  • Calcium Channel Blockers
  • Cannabinoids
  • Morpholines
  • Naphthalenes
  • Piperidines
  • Pyrazoles
  • Receptors, Cannabinoid
  • Receptors, Drug
  • (3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone
  • Acetylcholine
  • Rimonabant