δ-opioid Receptor-like Immunoreactivity in Healthy Colon and Inflammatory Bowel Disease

Crohn’s disease and ulcerative colitis (UC) are types of Infl ammatory Bowel Disease (IBD), a condition of unknown aetiology. Previous fi ndings from our laboratory suggest that [Met]-enkephalin and dynorphin A(1-8) are diff erentially altered in Crohn’s disease and UC suggesting a role for the opioid system in the pathophysiology of IBD. In this investigation, we have used immunohistochemistry to localise the δ-opioid receptor (δOR) in healthy human colon and in patients with IBD. δOR-like immunoreactivity (IR) was observed in the myenteric and submucosal plexuses, muscularis externa and mucosa in health and IBD. In comparison with healthy gut, δOR-like IR was decreased in both plexuses in the two forms of IBD; there was no diff erence between UC and Crohn’s. In the mucosal crypts, δOR-like IR was observed in putative neuroendocrine cells but not in enterocytes. Infl ammatory cells in the lamina propria and submucosa also appeared to show δOR-like IR. Changes in neuronal δOR are consistent with a role for the opioid system in the pathophysiology of IBD. δOR in infl ammatory cells and [Met]enkephalin-like IR in the colonic epithelium (this meeting) also support a role for opioids in chemotaxis