What is the difference between CB1 and CB2 receptors?

CB1 and CB2 are the two primary cannabinoid receptors, but they have distinct distributions and functions. CB1 receptors: predominantly expressed in the CNS — highest density in the basal ganglia, cerebellum, hippocampus, and prefrontal cortex. Also present in peripheral tissues including the liver, adipose tissue, and reproductive organs. CB1 activation by THC produces psychoactivity, analgesia, antiemesis, appetite stimulation, and memory impairment. CB2 receptors: predominantly expressed on immune cells (macrophages, T-cells, B-cells, microglia) and peripheral tissues. Minimal CNS expression under normal conditions, though expression increases during neuroinflammation. CB2 activation produces anti-inflammatory and immunomodulatory effects without psychoactivity. This distinction is clinically important: CB2-selective agonists (like beta-caryophyllene) may provide anti-inflammatory benefits without the psychoactive side effects of CB1 agonism.