Anales RANF

P.97 ADENOSINE A 2B RECEPTORS ON ENTERIC GLIA MEDIATE COLONIC DYSMOTILITY ASSOCIATED WITH HIGH FAT DIET- INDUCED OBESITY L. Antonioli 1 , V. D’Antongiovanni 1 , Carolina Pellegrini 1 , Matteo Fornai 1 , Laura Benvenuti 1 , Valentina Caputi 2,3 , Maria Cecilia Giron 3 , Rocchina Colucci 3 , Corrado Blandizzi 1 1 . University of Pisa, Pisa, Italy; 2 . University College of Cork, Cork, Ireland; 3 . University of Padova, Padova, Italy. At present, the role played by A 2B receptors (A 2B Rs) in the modulation of enteric glial cell (EGC) functions, and thereby their involvement in the pathogenesis of intestinal dysmotility associated with high-fat diet (HFD)-induced obesity remains unknown. We evaluated the in vitro effects of A 2B R ligands on colonic contractions in HFD-fed mice, also investigating the role of EGCs in this context. C57BL/6 mice were fed with standard diet (SD, 18% from fat) or HFD (60% from fat) for 8 weeks. Tachykininergic contractions were examined on colonic preparations in presence of BAY60-6583 (A 2B Rs agonist, 1 µ M) or MRS1754 (A 2B Rs antagonist, 0.01 µ M) with or without the gliotoxin fluorocitrate (FC, 50 µ M). A 2B R, glial fibrillary acid protein (GFAP) and substance P (SP) expression were examined by immunohistochemistry. To mimic an HFD, EGCs were incubated with palmitate (PA, 400 µ M) and/or lipopolysaccharide (LPS, 10 µ g/ml), with or without BAY60-6583 (0.05 µ M) and MRS1754 (0.25 µ M). The expression of toll-like receptors (TLR)-4 and SP release were evaluated in EGCs. The electrically-evoked colonic tachykininergic contractions were enhanced in HFD mice as compared to SD mice. MRS1754 enhanced these electrically-induced contractions in HFD mice, while it was less effective in SD mice. BAY60-6583 decreased tachykininergic contractions, with higher efficacy in HFD mice. The effects of A 2B R ligands on colonic contractions were blunted upon incubation with FC. HFD mice showed an increased expression of colonic A 2B Rs, GFAP and SP. In cultured EGCs, co-incubation with LPS and PA increased the TLR-4 expression and SP release, as compared with control cells. Under co-incubation with LPS and PA, BAY60-6583 decreased TLR-4 expression and SP release. Such effects were antagonized by MRS1754. HFD is associated with a hyperactivation of EGCs, likely through TLR-4, contributing to colonic tachykininergic motor dysfunction. In this setting, A 2B Rs expressed on EGCs modulate both the TLR-4 expression and the activity of excitatory tachykininergic nerves.