transmitter receptors, the CB receptor is a GPCR. A surprising piece of
the story is that the CB receptor occurs pretty much everywhere in the
brain and appears to be the most abundant of all known GPCR recep-
tors in the vertebrate brain.
Just as with the discovery of the opioid receptor nearly twenty
years earlier, the discovery of the CB receptor prompted a search
for molecules that functioned as its endogenous ligands. Within a
couple of years the first was discovered—it was a new molecule, not
previously known and written about, and the authors of the research
proposed a new name for the molecule: anandamide, from the San-
skrit word ananda, meaning bliss.
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N H
AnandamideAnandamide, also know as N-arachidonoylethanolamine, is an en-
dogenous agonist of the CB receptor, the first of several molecules to
be discovered that appear to function as neurotransmitters at the CB
receptor. Another endogenous agonist of the CB receptor is 2-arachi-
donylglycerol (2-AG).
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2-arachidonylglycerol (2-AG)Collectively these molecules are called endocannabinoids, even
though chemically they are not cannabinoids—that is, they do
not have structures that are directly related to THC. However, the
anandamide and 2-AG molecules must bend around in three dimen-