The immunocytochemical localisation of 'substance-P-degrading enzyme' within the rat spinal cord

The regional distribution of a neural endopeptidase ('substance-P-degrading enzyme', SPDE) within the rat spinal cord, as visualised by immunocytochemistry, closely paralleled the distribution of major substance P-containing nerve fibre systems. Thus, SPDE-immunoreactivity was present in laminae I and II of the dorsal horn, in large diameter neurones of the ventral horn and in the ependymal cells which line the central canal. The pattern of immunostaining, particularly in the dorsal horn, is consistent with the view that SPDE may function in the metabolism of substance P.