Editing Cannabinoid receptor (section)

=== Other ===
The existence of additional cannabinoid receptors has long been suspected, due to the actions of compounds such as [[abnormal cannabidiol]] that produce cannabinoid-like effects on [[blood pressure]] and [[inflammation]], yet do not activate either CB<sub>1</sub> or CB<sub>2</sub>.<ref name="pmid10570211"/><ref name="pmid17965195"/> Recent research strongly supports the hypothesis that the ''N''-arachidonoyl glycine ([[NAGly]]) receptor [[GPR18]] is the molecular identity of the abnormal cannabidiol receptor and additionally suggests that NAGly, the endogenous lipid metabolite of [[anandamide]] (also known as arachidonoylethanolamide or AEA), initiates directed [[Microglia#Chemokines|microglial migration]] in the CNS through activation of [[GPR18]].<ref name="pmid20346144"/> Other molecular biology studies have suggested that the orphan receptor [[GPR55]] should in fact be characterised as a cannabinoid receptor, on the basis of sequence homology at the binding site. Subsequent studies showed that GPR55 does indeed respond to cannabinoid ligands.<ref name="pmid17876302"/><ref name="pmid17704827"/> This profile as a distinct non-CB<sub>1</sub>/CB<sub>2</sub> receptor that responds to a variety of both endogenous and exogenous cannabinoid ligands, has led some groups to suggest GPR55 should be categorized as the CB<sub>3</sub> receptor, and this re-classification may follow in time.<ref name="pmid16517404"/> However this is complicated by the fact that another possible cannabinoid receptor has been discovered in the [[hippocampus]], although its gene has not yet been cloned,<ref name="pmid18482429"/> suggesting that there may be at least two more cannabinoid receptors to be discovered, in addition to the two that are already known. [[GPR119]] has been suggested as a fifth possible cannabinoid receptor,<ref name="pmid17906678"/> while the [[PPAR]] family of nuclear hormone receptors can also respond to certain types of cannabinoid.<ref>{{cite journal | vauthors = O'Sullivan SE | title = An update on PPAR activation by cannabinoids | journal = British Journal of Pharmacology | volume = 173 | issue = 12 | pages = 1899–910 | date = June 2016 | pmid = 27077495 | pmc = 4882496 | doi = 10.1111/bph.13497 }}</ref>