The CB1 receptors are primarily located on nerve cells in the brain, spinal cord, but they are also found in some peripheral organs and tissues such as the spleen, white blood cells, endocrine gland and parts of the reproductive, gastrointestinal and urinary tracts.
In the brain, the CB1 receptors are abundant in the cerebellum, basal ganglia, hippocampus and dorsal primary afferent spinal cord regions, which is why cannabinoids influence functions such as memory processing, physical discomfort and motor control. (1)
The CB2 receptors are mainly found on white blood cells, in the tonsils and in the spleen. The immune cells also express CB1, although there are fewer of them than CB2. In the immune system, one important function of the cannabinoid receptors is the regulation of cytokine release.(1)
Progress in Lipid Research, P. Pacher, R. Mechoulam; 2011