Differential Expression of Cannabinoid Receptors in the Human Colon: Cannabinoids Promote Epithelial Wound Healing

The purpose of the present study was to confirm the existence and the location of endogenous cannabinoid receptors, CB1 and CB2 receptors, in both normal and inflammatory bowel disease (IBD) human colonic tissue.  Additionally, this study sought to confirm the functionality of these receptors, including anti-inflammatory role and colon epithelial wound healing. 

Surgical samples were collected immediately after surgery from patients undergoing large bowel resection for colon cancer or from biopsy tissue samples taken from patients with IBD or Crohn’s disease.  For each tissue sample taken 3 measurements were performed after 24 hours of stimulation on each wound before introducing lysophosphatidic acid (LPA – substance known to help wound healing), endogenous cannabinoids (cannabis compounds that the human body naturally creates), or synthetic cannabis compounds.  Each measurement was performed at least 3 times to ensure precision.

Previous research has found that healthy human mucosa (found with the intestine) contains healthy amounts of endogenous compounds and cannabinoid receptors. Further, research has shown that endogenous cannabinoid receptors (receptors in our body that work with cannabis) play a significant role in the colon and disruptions to cannabinoid receptor pathways may account for ulcerative symptoms and delayed wound healing in IBD patients. 

This study showed that cannabinoid receptors (i.e., CB1 and CB2) play a pivotal role in the gut epithelium of humans.  This study provides evidence for the distribution of CB1 and CB2 cannabinoid receptors within the human colon and evidence that CB1 receptors inhibit smooth muscle contraction.  Endogenous cannabinoids and synthetic cannabinoids were both able to independently increase wound closure and when used together with LPA showed significantly increased wound closure.  It is suggested that these wound closures are likely to be mediated by the CB1 receptor.

This study concluded that CB1 cannabinoid receptor expression was particularly high.  Also, an increase of CB2 receptors in the colon epithelium plays an anti-inflammatory role for issues of IBD.  Overall, this study provides evidence that our human endogenous cannabinoid system is involved in epithelial wound healing and is found throughout the gut and that endogenous and synthetic cannabinoids create gut epithelial wound healing suggesting the potential for plant-based cannabinoids, such as THC and CBD.


Article Link: http://www.gastrojournal.org/article/S0016-5085(05)00929-7/pdf