Colonic motor dysfunctions in a mouse model of high-fat diet-induced obesity: an involvement of A 2B adenosine receptors.

Adenosine A _2B receptors (A _2B R) regulate several enteric functions. However, their implication in the pathophysiology of intestinal dysmotility associated with high-fat diet (HFD)-induced obesity has not been elucidated. We investigated the expression of A _2B R in mouse colon and their role in the mechanisms underlying the development of enteric dysmotility associated with obesity. Wild-type C57BL/6J mice were fed with HFD (60% kcal from fat) or normocaloric diet (NCD; 18% kcal from fat) for 8 weeks. Colonic A _2B R localization was examined by immunofluorescence. The role of A _2B R in the control of colonic motility was examined in functional experiments on longitudinal muscle preparations (LMPs). In NCD mice, A _2B R were predominantly located in myenteric neurons; in HFD animals, their expression increased throughout the neuromuscular layer. Functionally, the A _2B R antagonist MRS1754 enhanced electrically induced NK ₁ -mediated tachykininergic contractions in LMPs from HFD mice, while it was less effective in tissues from NCD mice. The A _2B receptor agonist BAY 60-6583 decreased colonic tachykininergic contractions in LMPs, with higher efficacy in preparations from obese mice. Both A _2B R ligands did not affect contractions elicited by exogenous substance P. Obesity is related with a condition of colonic inflammation, leading to an increase of A _2B R expression. A _2B R, modulating the activity of excitatory tachykininergic nerves, participate to the enteric dysmotility associated with obesity.