Localisation of Cannabinoid and Cannabinoid-Related Receptors in the Horse Ileum.
Authors: Galiazzo Giorgia, Tagliavia Claudio, Giancola Fiorella, Rinnovati Riccardo, Sadeghinezhad Javad, Bombardi Cristiano, Grandis Annamaria, Pietra Marco, Chiocchetti Roberto
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Colic remains a leading cause of equine morbidity and mortality, yet therapeutic options remain limited—particularly for cases involving intestinal inflammation and pain hypersensitivity. This Italian research team mapped the distribution of cannabinoid receptors (CB1 and CB2) and related receptors (PPAR-α, TRPV1, and 5-HT1a) across the equine ileum using immunohistochemistry on samples from six healthy horses, establishing for the first time a detailed anatomical basis for understanding how cannabinoid signalling might influence gastrointestinal function in this species. The receptors showed widespread but specific localisation: epithelial cells and enteric neurons expressed CB1, whilst immune cells in the lamina propria were CB2-positive; PPAR-α appeared in enteric neurons, glial cells, smooth muscle, and blood vessel tissue; and serotonin receptors concentrated in epithelial cells and immune cells. These findings suggest that cannabis-derived therapeutics could theoretically modulate both intestinal motility (via neuronal CB1), local inflammation (via immune cell CB2), and pain perception, though practitioners should note this is foundational anatomy work rather than evidence of clinical efficacy. Future studies examining receptor expression during inflammatory colic episodes and controlled trials of non-psychoactive cannabinoid compounds will be essential before any clinical application recommendations can be made.
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Practical Takeaways
- •This foundational anatomy study identifies where cannabinoid receptors are located in the horse's small intestine, supporting future research into cannabis-derived therapies for colic and intestinal inflammation
- •The widespread distribution of these receptors across epithelial, neuronal, glial and immune cells suggests multiple potential targets for therapeutic intervention in gastrointestinal disorders
- •While this is basic research only, it provides rationale for clinical trials investigating non-psychoactive cannabis molecules as adjunctive treatments for equine intestinal disease
Key Findings
- •Cannabinoid receptors CB1R and CB2R are widely distributed throughout the horse ileum in epithelial cells, enteric neurons, and enteric glial cells
- •Putative cannabinoid-related receptors (PPAR-α, TRPA1, 5-HT1aR) show distinct cellular localisation patterns including in inflammatory cells and smooth muscle
- •This immunohistochemical mapping provides a histological basis for investigating cannabinoid receptor function in equine gastrointestinal inflammatory diseases