Along with other mammals, human beings have endocannabinoid receptors — CB1, CB2, and possibly CB3 — throughout our bodies, particularly in the central nervous system and gastrointestinal system. Endocannabinoids (endogenous, meaning naturally occurring in the body) are found during the pre- and post-natal periods, and for the rest of natural life.
Endocannabinoids occur naturally in breast milk and have been found to trigger the first suckling, appetite, swallowing, digestion, sleep, and so forth in newborns. They continue to aid in appetite, food cravings, enjoyment of food, sleep regulation, growth, and more through childhood, adolescence, and adulthood. They even protect against certain kinds of newborn brain damage and feeling the full impact of digestive pain. Researchers in Israel and the U.K. lead the way in studying the functions of the endocannabinoid system, particularly in mice and rats. Though we know definitively that cannabinoid receptors exist in humans, we have discovered much of what we know about this system’s functions through studies on animals.
Studies on cannabinoid receptors and breastfeeding in animals have shown cannabinoids to be a promising treatment for failure to thrive, identifying dysfunctional endocannabinoid receptors as a cause of newborn inability to ingest food and subsequently, failure to thrive. Furthermore, in at least one study of infant mortality, human babies of mothers who used cannabis while pregnant were at lower risk of infant mortality than those infants whose mothers used no substance at all. This result has not been fully explained, but one theory (see Fride, Bregman & Kirkham, 2005) is that the exocannabinoids (exogenous, meaning from outside the body) from cannabis, transferred through breast milk, stimulate appetite functions by binding to CB1 endocannabinoid receptors. Failure to thrive is associated with a blockage of these receptors.
Studies on the Endocannabinoid System in Humans & Other Animals
- Fride, E. et al. (2001). Critical role of the endogenous cannabinoid system in mouse pup suckling and growth. European Journal of Pharmacology, 419(2-3), 207-214.
- Fride, E. (2002). Endocannabinoids in the central nervous system—an overview. Prostaglandins, Leukotrienes and Essential Fatty Acids, 66(2-3), 221-233.
- Fride, E. (2002). Cannabinoids and Feeding: The Role of the Endogenous Cannabinoid System as a Trigger for Newborn Suckling. Journal of Cannabis Therapeutics, 3/4, 49-60. (free full text available)
- Fride, E. (2004). The endocannabinoid-CB receptor system: Importance for development and in pediatric disease. Neuroendocrinology Letters, 25(1-2), 24-30.
- Fride, E. (2004). The endocannabinoid-CB(1) receptor system in pre- and postnatal life. European Journal of Pharmacology, 500(1-3), 289-297.
- Fride, E. et al. (2003). Milk intake and survival in newborn cannabinoid CB1 receptor knockout mice: evidence for a “CB3″ receptor. European Journal of Pharmacology, 461(1), 27-34.
- Fride, E., Bregman, T., & Kirkham, T.C. (2005). Endocannabinoids and food intake: Newborn suckling and appetite regulation in adulthood. Experimental Biology and Medicine, 230(4), 225-234.
- Gómez, R. et al. (2002). A peripheral mechanism for CB1 cannabinoid receptor-dependent modulation of feeding. Journal of Neuroscience, 22(21), 9612-9617. (free full text available)
- Hornby, P.J. & Prouty, S.M. (2004). Involvement of cannabinoid receptors in gut motility and visceral perception. British Journal of Pharmacology, 141(8), 1335-1345. (free full text available)
- Kirkham, T.C. & Williams, C.M. (2001). Endogenous cannabinoids and appetite. Nutrition Research Reviews, 14(1), 65-86.
- Kirkham, T.C. (2005). Endocannabinoids in the regulation of appetite and body weight. Behavioural Pharmacology, 16(5-6), 297-313.
- Kirkham, T.C. (2009). Cannabinoids and appetite: food craving and food pleasure. International Review of Psychiatry, 21(2), 163-171.
- Mechoulam, R. et al. (2006). Endocannabinoids, feeding and suckling—from our perspective. International Journal of Obesity, 30(Supp. 1), S24-28. (free full text available)
- Mostafeezur, R.M. et al. (2012). Cannabinoids facilitate the swallowing reflex elicited by the superior laryngeal nerve stimulation in rats. PLoS One, 7(11). (free full text available)
- Shouman, B. et al. (2006). Endocannabinoids potently protect the newborn brain against AMPA-kainate receptor-mediated excitotoxic damage. British Journal of Pharmacology, 148(4), 442-451. (free full text available)
- Vickers, S.P. & G.A. Kennett. (2005). Cannabinoids and the regulation of ingestive behaviour. Current Drug Targets, 6(2), 215-223.