trkA, CGRP and IB4 expression in retrogradely labelled cutaneous and visceral primary sensory neurones in the rat.

The pattern of trkA expression in relation to other neurochemical markers (CGRP and IB4) was investigated in primary sensory neurones innervating either the skin or bladder. Retrograde tracing using the fluorescent marker Fast Blue was performed followed by histochemistry. A greater proportion of visceral afferents compared with cutaneous afferents were trkA-immunoreactive (75% and 43%, respectively).