Inability of β‐amyloid (25–35) to bind to central nervous system neurokinin 1 receptors

Abstract β‐Amyloid (1–40) has recently been shown to exhibit both neurotoxic and neurotrophic properties. The putatively active moiety is β‐(25–35), which has a structural homology to the human tachykinin substance P. Substance P, which preferentially binds to neurokinin 1 (NK1) receptors in the central nervous system (CNS), has been shown to block the neurotoxic effects of β‐amyloid (1–40). These data suggest that effects of β‐amyloid may be mediated by an NK1 receptor‐mediated process. However, in the present study, we demonstrate that β‐(25–35) is unable to competitively inhibit the binding of 0.15 nM 125 I‐substance P from rat CNS NK1 receptors. Therefore, the mechanisms of action of β‐amyloid neurotoxic effects are probably not to be mediated through a NK1 receptor‐mediated process.