Distribution and release of Substance P in the central nervous system

Following the discovery of Substance P (SP) in extracts of equine gut and brain by von Euler and Gaddum (1931), a considerable number of studies have been carried out on the distribution and pharmacology of this substance in various mammalian tissues. The earlier work has been well reviewed by Lembeck and Zetler (1962). SP was found to be present in relatively high concentrations in various nervous tissues, particularly in sensory nerve pathways. The idea that SP might correspond to the ‘Sensory Transmitter Factor’ studied by Hellauer and Umrath (1947, 1948) in extracts of dorsal root was also suggested some 25 years ago by Lembeck (1953), and has been championed particularly vigorously since then by this author (Lembeck and Zetler, 1962 and Lembeck this volume, chapter 8). Latterly the work of Otsuka and his colleagues has provided strong support to the view that SP functions as a sensory transmitter in the spinal cord (Otsuka and Konishi, 1975). Earlier studies on SP were hampered by the limited availability of purified material, and by the lack of a simple, specific and sensitive assay method. This situation has changed dramatically since the elucidation by Leeman and her colleagues and by Studer et al. (1973) of the chemical structure of SP as an undecapeptide, (Chang and Leeman, 1970; Chang et al., 1971; Leeman and Mroz, 1974) and by the chemical synthesis of the peptide (Tregear et al., 1971) and the development of a radioimmunoassay technique (Powell et al., 1973). More recently, an immunohistochemical technique for visualising the cellular localisation of SP has been developed and applied by Nilsson et al. (1974).