P2X receptors in the rat duodenal villus

Immunohistochemical techniques were performed on freshly frozen sections of the duodenum of the rat using specific polyclonal antibodies to unique peptide sequences of P2X 1–7 receptors. Of the antibodies to the seven known P2X receptor subtypes that mediate extracellular signalling by nucleotides, three reacted with discrete structures in the duodenal villus of the rat. Anti-P2X 1 reacted with the capillary plexus in the intestinal villus, which did not extend to the crypt region, suggesting that nucleotides may be involved in the uptake and transport of metabolites. Anti-P2X 5 immunostained the membranes of the narrow ”stem” of villus goblet cells, where the nucleus and cell organelles reside, possibly influencing synthesis and release of mucins. P2X 7 receptor immunoreactivity was only seen in the membranes of enterocytes and goblet cells at the tip of the villus, where cells are exfoliated into the lumen, consistent with earlier findings that P2X 7 is involved in apoptotic events. Thus, in complex structures such as the intestinal villus, purinoceptors appear to participate in several and diverse signalling functions.