Endocannabinoids definition

By definition (Di Marzo and Fontana 1995), endocannabinoids act primarily at cannabinoid CBi and/or CB2 receptors, and they do so with varying affinity and efficacy. AEA, NADA and 2-AGE are more selective for CBi, with the following rank of affinity AEA>2-AGE>NADA. 2-AG has almost the same affinity for both receptors, and its Ki varies considerably according to the experimental conditions. Several assays have been used to examine the functional activity of endocannabinoids and to compare it with that of synthetic cannabinoids and THC (Pertwee 1997), and those used most often are ... 

Using CB, knockout animals, a study in hippocampal slices definitively showed that activation of the CB, receptor was responsible for the downstream inhibition of presynaptic VDCC in cells in which DSI was produced (Wilson et al., 2001). The investigators also showed that a specific subtype of GABAergic intemeuron is targeted by endocannabinoids. In this case, activation of CB, receptors led to the specific inhibition of N- but not P/Q- type calcium channels, and this resulted in decreased release of neurotransmitter. 

By definition, cannabinoids comprise a variety of distinct chemical classes which bind to the cannabinoid receptor. These include the classical cannabinoids structurally related to tetrahydrocannabinol, the non-classical cannabinoids, the aminoalkylindoles, the eicosanoids related to the endocannabinoids, 1,5-diarylpyrazoles, quinolines and atylsulphonamides and additional compounds that do not fall into these standard classes. According to their production and origin, there are three types of cannabinoids phytocannabinoids, endogenous cannabinoids, and synthetic cannabinoids. 

---