The chromogranin A-derived peptide catestatin has previously been shown to be a constituent of the sensory innervation of the eye and dental pulp. The antibody used in these studies not only recognizes authentic catestatin but also larger molecules containing the sequence of catestatin. Therefore, the authors now aimed to explore whether there are additional molecular forms present in the rat skin, rat trigeminal ganglion and rat dorsal root ganglia apart from free catestatin.

Western blot analysis was performed in these tissues and and double immunofluorescence techniques in rat dorsal root ganglia.

A very prominent band was found at approximately 50 kDa in the skin representing a middle-sized fragment containing the sequence of this peptide. Recently, the same result has been obtained in the dental pulp indicating that this fragment might represent a main molecular form in various other tissues of the body. It is likely of sensory nature since the band was also present of weaker intensity both in the trigeminal ganglion and dorsal root ganglia and since abundant cells expressed catestatin-like immunoreactivity in rat dorsal root ganglia. Another small sized fragment of weaker intensity was found in these tissues as well. No band was observed in the position of intact chromogranin A in the Western blot.

Chromogranin A is proteolytically processed in sensory ganglia to at least two fragments containing the sequence of catestatin which are then anterogradely transported to the skin and the 50 kDa fragment obviously becomes aggregated there in nerve endings.