The body beyond the brain
Immune cells, gut, bone and skin
▶ Play this chapter The script
Every line as it is spoken in the film, in order.
Now come back down, past the crowd and into one body. These locks don't stop at the brain.
Remember CB2, the second lock on your immune cells? Mice born without it tend to get worse inflammation.
In your gut, CB1 sits on the nerves of the gut wall. Remove it, and colitis in mice gets far worse.
Your bones are rebuilt all the time, and CB2 helps keep the balance. Without it, mice lose bone faster as they age.
Your skin makes its own keys too. Take away both locks, and an allergic rash in mice flares much worse.
The same system runs through your immune cells, your gut, your bones and your skin. The brain is just where we found it first.
Sources
Every claim in this chapter with its grade: E established · M emerging (one or two studies, or animals only) · F framework.
- EGaliègue S et al. Expression of central and peripheral cannabinoid receptors in human immune tissues and leukocyte subpopulations. Eur J Biochem 1995;232:54–61. (CB2 10–100 times more abundant than CB1 in immune tissues; B cells highest) link
- MTurcotte C et al. The CB2 receptor and its role as a regulator of inflammation. Cell Mol Life Sci 2016;73:4449–70. (review: mice lacking CB2 repeatedly show worse inflammation) link
- MMassa F et al. The endogenous cannabinoid system protects against colonic inflammation. J Clin Invest 2004;113:1202–9. (mice: CB1 on gut-wall neurons; colitis worse without CB1, milder without FAAH) link
- MOfek O et al. Peripheral cannabinoid receptor, CB2, regulates bone mass. Proc Natl Acad Sci USA 2006;103:696–701. (mice without CB2: faster age-related bone loss) link
- MKarsak M et al. Attenuation of allergic contact dermatitis through the endocannabinoid system. Science 2007;316:1494–7. (mice lacking CB1 and CB2: worse allergic skin inflammation) link
- MBíró T et al. The endocannabinoid system of the skin in health and disease: novel perspectives and therapeutic opportunities. Trends Pharmacol Sci 2009;30:411–20. (review: skin cells make and respond to their own endocannabinoids) link
- EDevane WA, Dysarz FA, Johnson MR, Melvin LS, Howlett AC. Determination and characterization of a cannabinoid receptor in rat brain. Mol Pharmacol 1988;34:605–13. link
- EMunro S, Thomas KL, Abu-Shaar M. Molecular characterization of a peripheral receptor for cannabinoids. Nature 1993;365:61–5. (CB2) link