Involvement of Substance P and the Neurokinin-1 Receptor in Radiation-Induced Hair Loss in Mice

Abstract

We investigated the involvement of substance P (SP) and the neurokinin-1 receptor (NK₁R) in the development of radiation-induced hair loss in mice. A dose of 40 Gy of gamma irradiation induced hair loss from the 10th to at least the 60th day after irradiation. A specific NK₁R antagonist, CP-99,994, significantly delayed radiation-induced hair loss and reduced its severity. Furthermore, gamma irradiation induced the expression of preprotachykinin-A, a precursor protein of SP, mRNA in irradiated murine skin on the 10th and 30th days after irradiation. These results indicated that gamma irradiation-induced hair loss was mediated by SP via NK₁R.