Browsing Pathways

2-Arachidoylglycerol acts as a full agonist of both CB1 and CB2 receptors. Here, its numerous effects on CB1 receptors are presented, including a route of its biosynthesis. Within the postsynaptic neuron, PIP2 is hydrolyzed to form a diacylglycerol molecule, which is then further hydrolyzed with the membranous enzyme DAGLa to form 2-AG. The completed 2-AG molecule is then released from the postsynaptic membrane and acts retroactively on CB1 receptors located on the presynaptic membrane. Acting as a G-protein coupled receptor, CB1 directly activates mitogen activated protein kinase (MAPK) and nitric oxide synthase. The activation of MAPK induces its own signalling pathway, which regulates mitosis and the cellular cycle through translation and transcription. Nitric oxide synthase is activated to produce nitric oxide, which has a number of roles in neurons, most notable of which is promoting neuroplasticity through its effect on potassium channels. Nitric oxide also activates soluble guanylyl cyclase, which mediates calcium channels through its production of cGMP. Apart from its activating action, the activated CB1 receptor also inhibits both calcium channels and forskolin activated adenylate cyclase. The inhibition of calcium channels works directly to block the flow of calcium ions into the presynaptic neuron, while the inhibition of adenylate cyclase decreases levels of cAMP within the neuron, leading to activation of potassium channels and focal adhesion kinase (FAK). FAK is involved in intracellular signalling that promotes cell migration and adhesion, while potassium channels work to pump potassium ions out of the presynaptic neuron and into the synaptic cleft.