What is the endocannabinoid system and why does it matter?

The endocannabinoid system (ECS) is a neuromodulatory system present in all vertebrates, discovered in the early 1990s through research on how THC works. It consists of: (1) Endogenous cannabinoids (endocannabinoids): anandamide (AEA) and 2-arachidonoylglycerol (2-AG), produced on-demand from cell membrane lipids; (2) Cannabinoid receptors: CB1 (primarily in the brain and CNS) and CB2 (primarily in immune cells and peripheral tissues); (3) Enzymes: FAAH (degrades anandamide) and MAGL (degrades 2-AG). The ECS regulates synaptic plasticity, pain, mood, appetite, memory, immune function, and stress response. It operates primarily through retrograde signaling — postsynaptic neurons release endocannabinoids that travel backward to inhibit presynaptic neurotransmitter release. This "dimmer switch" function explains why cannabinoids affect so many different physiological processes.