Neuropeptide FF analog RF9 is not an antagonist of NPFF receptor and decreases food intake in mice after its central and peripheral administration

► Binding of RF9 to NPFF2 receptor was confirmed. ► RF9 did not reverse phosphorylation of MAPK/ERK1/2 stimulated with [Tyr1]NPFF. ► RF9 did not inhibit anorexigenic effect of [Tyr1]NPFF. ► RF9 exhibited anorexigenic effect in mice after central and peripheral administration. ► This doubts an image that RF9 acts as a NPFF antagonist.