Distribution of P2X3-Immunoreactive Fibers in Hairy and Glabrous Skin of the Rat

The study investigated the pattern of P2X₃-immunoreactive (IR) fiber innervation in the hairy and glabrous skin of male Sprague-Dawley rats using light microscopic immunocytochemistry. Results showed extensive P2X₃-IR fibers throughout the upper and lower dermis, with thick bundles running parallel to the dermal-epidermal junction and projecting thin collateral axons into the epidermis, creating a dense network. The distribution of P2X₃-IR fibers was more extensive than CGRP-IR fibers and also innervated hair follicles but were rarely near glands and blood vessels. These findings suggested a primary role for P2X₃-IR fibers in detecting noxious stimuli in cutaneous tissue and provided an anatomical basis for future studies on the distinct functional role of nonpeptidergic nociceptors in nociceptive signal transmission.