Abstract: Objective To study the distribution of purinergic P2XSUB>3/SUB> receptor immunoreactive afferent fibers in the rat pharyngeal mucosa and provide morphological evidence for exploring the role of ATP in the signal transduction of sensory stimuli. Methods Twelve adult Wistar rats were used and immunofluorescenthistochemical double-labeling technique combined laser confocal scanning microscope was applied in the present study. Results 1.P2XSUB>3/SUB> immunoreactive fibers were observed on sections from all parts of pharyngeal mucosa. Two types of positive fibers were found. One was free nerve fibers covered with many varicosities. Another one ramified in mucosa and showed complex arborization endings. Nerve plexus in mucosa were formed by P2XSUB>3/SUB> immunoreactive fiber ramifications. 2.Most calcitonin generelated peptide (CGRP) positive fibers intermingled with P2XSUB>3/SUB> immunoreactive fiber arborizations. A few P2XSUB>3/SUB> immunoreactive fibers were covered with many varicosities co-localized with CGRP. 3.In petrosal ganglion, most neurons were stained with P2XSUB>3/SUB> or CGRP immunoreactivity and small number of P2XSUB>3/SUB> immunoreactive neurons costained with CGRP. Conclusion These results indicated that the different types of afferent fibers in rat pharyngeal mucosa expressed purinergic P2XSUB>3/SUB> receptor immunoreactivity and ATP might be related to nociceptive or physiological signals transduction in rat pharyngeal mucosa.

Key words: Purinergic receptor, Calcitonin gene-related peptide, Afferent fiber, Pharyngeal mucosa, Immunofluoresenthistochmistry, Rat