The localization of fluoride-resistant acid phosphatase (FRAP) in the pelvic nerves and sacral spinal cord of rats.

The enzyme fluoride-resistant acid phosphatase (FRAP) is present in many small diameter cutaneous but not muscle afferent nerve fibres, in the rat. Here it is shown that it is also present in many afferent nerve fibres in a visceral nerve. The depletion of the enzyme from the central terminals of fibres that are cut peripherally provides a means of mapping the main projection areas of FRAP-containing afferents within the central nervous system. It was found that pelvic afferents containing FRAP have a major projection lateral to the neck of the dorsal horn and the area of the intermediolateral cell column in spinal cord segments L6 and S1, in contrast to the main projection of cutaneous FRAP afferents whose terminations form a horizontal band in the superficial dorsal horn.