Chronic non-peptide neurokinin receptor antagonist treatment alters striatal tachykinin peptide and receptor gene expression in the rat.

The neurokinin-1 receptor (NK-1R) and the tachykinin peptide substance P (SP) are found throughout the central nervous system (CNS) and are involved in the regulation of sensory, cardiovascular, and inflammatory function. Selective antagonists for the NK-1R such as CP-122,721 block NK-1R-mediated responses both in vitro and in vivo. This study investigated the effects of long-term daily CP-122,721 treatment on gene expression of SP and the NK-1R in the striatum and hindbrain of the rat. The striatum and hindbrain of rats receiving CP122,721 (5, 30, or 150 mg/kg) once-daily for 30 days were assayed for SP- and NK-1R-encoding mRNAs using solution hybridization-nuclease protection assays. Results show that treatment with CP-122,721 significantly increased SP-encoding mRNA and NK-1R mRNA levels in the striatum, but not in the hindbrain. The ability of CP-122,721 to alter SP and NK-1R gene expression may provide a use for non-peptide neurokinin receptor antagonists in the modulation of systems regulated by NK-1R function.