Localisation of Cannabinoid and Cannabinoid-Related Receptors in the Horse Ileum

Colic is a common digestive disorder in horses and one of the most urgent problems in equine medicine. A growing body of literature has indicated that the activation of cannabinoid receptors could exert beneficial effects on gastrointestinal inflammation and visceral hypersensitivity. The localisation of cannabinoid and cannabinoid-related receptors in the intestine of the horse has not yet been investigated. The purpose of this study was to immunohistochemically localise the cellular distribution of canonical and putative cannabinoid receptors in the ileum of healthy horses. Distal ileum specimens were collected from six horses at the slaughterhouse. The tissues were fixed and processed to obtain cryosections which were used to investigate the immunoreactivity of canonical cannabinoid receptors 1 (CB1R) and 2 (CB2R), and three putative cannabinoid-related receptors: nuclear peroxisome proliferator-activated receptor-alpha (PPARcz), transient receptor potential ankyrin 1 and serotonin 5-HT1 a receptor (5-HT1aR). Cannabinoid and cannabinoid-related receptors showed a wide distribution in the ileum of the horse. The epithelial cells showed immunoreactivity for CB1R, CB2R and 5-HT1aR. Lamina propria inflammatory cells showed immunoreactivity for CB2R and 5-HT1IaR. The enteric neurons showed immunoreactivity for CB1R, transient receptor potential ankyrin 1 and PPAR alpha. The enteric glial cells showed immunoreactivity for CB1R and PPAR alpha. The smooth muscle cells of the tunica muscularis and the blood vessels showed immunoreactivity for PPAR alpha. The present study represents a histological basis which could support additional studies regarding the distribution of cannabinoid receptors during gastrointestinal inflammatory diseases as well as studies assessing the effects of non-psychotic cannabis-derived molecules in horses for the management of intestinal diseases. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study utilized immunohistochemistry to reveal the widespread distribution of cannabinoid and cannabinoid-related receptors in the ileum of healthy horses, providing a histological basis for further research on the distribution of cannabinoid receptors during gastrointestinal inflammatory diseases and the effects of non-psychotic cannabis-derived molecules in managing intestinal diseases in horses.