Immunohistochemical evidence for ATP receptors in human dental pulp

Evidence is accumulating which supports a role for ATP in the initiation of pain by acting on P2X receptors, in particular P2X(3), expressed on nociceptive afferent nerve terminals. To investigate whether this receptor plays a role in dental pain, we studied the presence and distribution of P2X(3) receptors in human dental pulp, and their co-localization with other neural markers. Pulps were removed from extracted third molars and immunohistochemically stained with an antibody against P2X(3) receptors. P2X(3) immunoreactive (-ir) nerve fibers were detected in the main body of the pulp, in the subodontoblastic plexus of Raschkow, and within the odontoblastic area. Co-localization of the P2X,-ir neurons with neurofilament protein (NIF) showed that the majority of the fibers were positive for both NF and P2X(3). Double labeling with isolectin B4 (IB4) showed that all P2X(3)-ir neurons also bind IB4. We conclude that P2X(3) receptors are present on both myelinated and unmyelinated nerve fibers in human dental pulp and may play a role in dental pain mechanisms.