The distribution of P2X5 purinergic receptors in the enteric nervous system of mouse.

The distribution of the P2X(5) purinoceptor in the enteric nervous system of the mouse was studied by immunohistochemistry. P2X(5) receptor immunoreactivity was widely distributed in myenteric and submucosal plexuses throughout the gastrointestinal tract. In myenteric plexuses, immunoreactivity for the P2X(5) receptor was observed in nerve fibres that enveloped ganglion cell bodies, and possibly on glial cell processes. P2X(5) receptor immunoreactivity was colocalised with vasoactive intestinal peptide and surrounded ganglion cells that contained calretinin, calbindin or nitric oxide synthase. In the submucous plexus, P2X(5) receptor immunoreactivity occurred throughout the cytoplasm and on the surface membranes of the nerve cells. Double-labelling studies showed that 22%, 9%, 6% and 68% of P2X(5) receptor-immunoreactive neurones were also immunoreactive for calretinin, calbindin, nitric oxide synthase and vasoactive intestinal peptide, respectively. Thus, the P2X(5) receptor subunit is expressed in specific functional groups of neurones. P2X(2) and P2X(3) receptors were also present in the mouse enteric plexuses but no immunoreactivity for P2X(1), P2X(4) or P2X(6) receptors was found.