Neurochemical identification of enteric neurons expressing P2X(3) receptors in the guinea-pig ileum.
It was hypothesised that P2X(3) receptors, predominantly labelling spinal and cranial sensory ganglionic neurons, are also expressed in intrinsic sensory enteric neurons, although direct evidence is lacking. The aim of this study was to localise P2X(3) receptors in the enteric nervous system of the guinea-pig ileum, and to neurochemically identify the P2X(3)-expressing neurons. In the submucous plexus, cholinergic neurons expressing calretinin (CRT), were immunostained for P2X(3). These neurons made up about 12% of the submucous neurons. In the myenteric plexus, approximately 36% of the neurons expressed P2X(3). Half of the latter neurons were immunoreactive for CRT, whereas about 20% were immunoreactive for nitric oxide synthase (NOS). Based on earlier neurochemical analysis of enteric neurons in the guinea-pig, the myenteric neurons exhibiting P2X(3)/CRT immunoreactivity were identified as longitudinal muscle motor neurons, and those expressing P2X(3)/NOS immunoreactivity as short inhibitory circular muscle motor neurons. In both plexuses, no colocalisation was observed between P2X(3) and calbindin, a marker for intrinsic sensory neurons. Multiple staining with antisera raised against somatostatin, neuropeptide Y, substance P or neurofilament protein did not reveal any costaining. It can be concluded that in the guinea-pig ileum, intrinsic sensory neurons do not express P2X(3) receptors. However, this does not negate the possibility that extrinsic sensory nerves expressing P2X(3) are involved in a purinergic mechanosensory transduction pathway as demonstrated in other organs.
Van Nassauw
Luc
L
Laboratory of Cell Biology and Histology, University of Antwerp (RUCA), Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Brouns
Inge
I
Adriaensen
Dirk
D
Burnstock
Geoffrey
G
Timmermans
Jean-Pierre
JP
D000818:Animals; D006168:Guinea Pigs; D007082:Ileum / Q000737:chemistry*; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D009474:Neurons / Q000737:chemistry*; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis*; D058477:Receptors, Purinergic P2X3
D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3