Endocannabinoids: Getting the message across

摘要

The endocannabinoids have emerged as important intercellular signals in the nervous system. The fatty acid amide arachidonylethanolamide (anandamide) is the prototypical endocannabinoid, i.e., an endogenous ligand of the G protein-coupled cannabinoid receptor in the brain, CB1, which binds the main psy-choactive component of marijuana and other derivatives of Cannabis sativa (1). After a rise in intracellular calcium or activation of certain neurotransmitter receptors, endocannabinoids are synthesized by cleavage of phospholipid precursors that are present in cellular membranes (2). They often act as retrograde messengers, emanating from morphologically undifferentiated regions of postsynaptic principal cells and traveling backwards across synapses, where they transiently inhibit the release of either the inhibitory neurotransmitter γ-amino-butyric acid (GABA) or the excitatory transmitter glutamate (see Fig. 1 and ref. 3 for a review). This powerful influence on synaptic transmission enables the endocannabinoids to help regulate behaviors, such as feeding (4), fear (5), and anxiety (6).