But even this apparently benign role may have a darker side as substance P immunoreactive astrocytes have been identified in MS plaques (Kostyk et al., 1989), and a requirement for substance P/NK-1R interactions has been reported for the maintenance of chronic inflammation in experimental autoimmune encephalomyelitis (EAE) mouse models of MS (Reinke et al., 2006). Here, TAC1 is linked to experimental autoimmune encephalomyelitis.