RF9 hydrochloride is a potent and selective Neuropeptide FF receptor antagonist, with Ki values of 58 and 75 nM for hNPFF1R and hNPFF2R, respectively[2].In Vitro: RF9 (10 μM) pretrement completely blocks NPFF induced neurite outgrowth of Neuro 2A cells[2].In Vivo: RF9 (0.1 mg/kg, s.c. ) with heroin coadministration prevents heroin-induced delayed hyperalgesia and tolerance.
RF9 (10 μg) infused alone does not result in a significant alteration of MAP or heart rate. Conversely, MAP and heart rate increases evoked by NPFF are significantly blocked when NPFF is applied in conjunction with RF9.