Labeling of cutaneous sensory nerve endings with axonally transported horseradish peroxidase and wheat germ agglutinin-horseradish peroxidase conjugate: a methodological study in the rat

Abstract

Practical aspects on the use of horseradish peroxidase (HRP) and wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) to trace peripheral cutaneous nerve endings have been studied. The parameters studied included (i) application site of the tracer, (ii) postapplication survival time, (iii) tracer concentration and (iv) tracer volume. These parameters were examined in the glabrous skin of the rat hindpaw. The best results were obtained with injections of 1 μl WGA-HRP (20 μg/μl) in dorsal root ganglia innervating the examined cutaneous region and a postinjection survival time of 18–36 h. With this approach extensive and heavy labeling was achieved of epidermal nerve endings, nerve endings in Merkel cell-neurite complexes and Meissner corpuscles. Useful, but less extensive labeling of these types of peripheral nerve endings, was obtained with injections of HRP in the lumbar spinal cord dorsal horn.