Traditionally, the activity of cannabinoid (CB) agonists was thought to be transduced by a pair of G protein-coupled receptors, CB1 and CB2.CAY10429 (abnormal cannabidiol) is a synthetic regioisomer of cannabidiol that fails to elicit either CB1 or CB2 responsiveness and is without psychotropic activity. CAY10429 induces endothelium-dependent vasodilation via a CB1/CB2/NO-independent mechanism.At a dose of 20 µg/g in rats, CAY10429 showed hypotensive activity that could not be antagonized by cannabidiol or SR141716A. CAY10429 is therefore believed to activate a third type of cannabinoid receptor, provisionally called the non-CB1/CB2 endocannabinoid receptor. CAY10429 also acts via these receptors to regulate the migratory activity of murine BV-2 microglial cells, with an EC50 of 600 nM.